driver lg mx7000

B_=_TAVNLA._
t.ECOP'/'
JUNE 1070
U,S. ENVIRONMENTAL PROTECTION AGENCY
OFFICEOF NOISEA[IATEMENTAND CONTnOL
WadzinuIon.
O.C.204(]0
SURFACE TRANSPORTATION
EXHAUST SYSTEM NOISE SYMPOSIUM
OCTOOER 11, 12, 13, 1977
Howard Johnson's - O'Hme
Chicl_go.Iflinoh_
f
i
i.
r
Tabluof Cnntents
AuriouIICEIIEtIT
OF
SURFACETRARSPORTATIOrl
EXIIAUST
SYSTEMROISE SYIIPOSIUM
iv
AGENDA
vl
IDTRODUCTORY
ADDRESSFOR TIIESURFACETRArISPORTATIOrl
EXIIAUST
SYSTE_I
IIOISESYHPOSIUI.I
Hill]amE. Roper
U. S, Eiwlronm_ntal
Protection
Agency
IIEUCM
TEST PROCEDURESAridEXHAUSTSYSTEHPERFOFCIAMCE
PREDICTION
P.O.A.L.Davies
Uallversity of Southampton
Southampton,
England
AUTOIIOTIVE
EXUAUSTSYSTEMEVALUATIOM
D. A. D1nser
Field Dynamics Research Departl_nt
Genera]rlotors
ResearchLaboratories
Harren,Htchloan
TIIEIIET#{OL)
OF fIEASURIFIG
EXHAUSTSYSTEII
fiOISE
A STUDY OM THE IIEDUCTIOM
OF TIIEEXIIAUST
rlOISEOF LARGETRUCKS
Mlnoichl Inagawa
C_ponent TestingSection,TestingDept,
MitsoblshlMotor Comnany
KawasaklCity, tlana.rlalla:
Japan
'
•' .'
'
:. ,
'%
, ,
i
5
/,9
?9
HETI+OD
AridAPPARATUSFOR MEASURI)IG
HUFFLEIt
PERFOMAtlCE
Peter Cheng
StemcoManufacturing
Co,
LongvlekhTexas
io9
OPTI|fiJH
DESIGtl
OF IiUFFLERS
l)r,Donald IBaXa
UnIversttyof Hlsconsln_ExtensionDept,
Hadlsentk(l
sconsln
115
DEMC|ITESTArR)AMALOGSIMULATIONTECIIRIQUES
FOR ERGINE
tlUFFLEREVALUATION
Cec1_
R,Sparks
ApplledPhysicsDivision
Southvfest
ResearchInstitute
San AntonloDTexas
143
(;
!i: :/
,.,._,_........
_,, :,_,__._,t_,_._,_._(_)_V_
_
COt.i._IZllTS
OilEVALUATIONTECIIIII_ES
OF EXJiAUST
SYSTEM
IIOISECOIITROL
CIlARACTERISTICS
U. t_. Rowley
Donaldson Co.
l.linncapo|
Is,I,II nn.
A DERCII
TEST FOR RAPIDEVALUATIONOF IIUFFLER
PERFORMAilCE
A. F. Seybert
Dept.of rlechanlcal
Englncerlng
Universityof ICentuc_
Lexington,Kentucky
161
181
AflALYTICAL
ADD EXPERIMERTAI.
TESTIRGPROCEDURES
FOR QUIETIIIG
TIIO-STROKE
EI_GIIIES
203
Donald L. Hargolls
Dept.of HnchanicalEngineering
Universityof California
Davis,California
POllEROR PRESSURE- A DISCUSSIOROF CURRENTALTERRATIVESIN
EXIIAUST
SYSTEMACOUSTICEVALUATIOII
Larryd. Erlksson
l_eIsnn
Industries,Inc.
Stoughton, Hlsconstn
A COMPUTER.AIDED
APPROACII
TOIIARD
PERFOR_RCEPREDICTIORSFOR
EIIGINEEXIIADST
HUFFLER
John E. Sneckenberoer
l_est
Vtrgtntn University
College of Engineering
Morgentovm, W, Virginia
REVIEll OF INTERRALcOr_DUSTIOR
EflIIIREEXIIAUST
IfllFFI.IRG
IlaIcoIm J. Crocker
Ray N. llerrlck
Laboratories
PurdueUniversity
Wesl Lafayette,Indiana
SIIOCK-TI/IIE
flETIIODS
FOR SItlULATIIIC,
EXIIAUST
PRESSUREPULSES
OF SMALLIIIGtI-PERFOfi_RCEEflOIffES
U. Sturtevant
CaI1fornlaInstltgte
of Technology
Pasaden_
_ California
:
;
" "
CORRELATIOrl
OR riOTIIETIICErl
flEIICII.TESTS
AridOOTSII)E
IIEASUREMEflTS
FOR SrlO_10UILES
Jean Rlchols
Bombardier
ResearchCenter
Valee_rt,Quebec
Canada
233
;267
29_
3_9
3t_i
IIEASURI]IUIT
OF UI(ilfIE
EXIrAUST
NOISE IN nY$1ArlOfl[TER
ROOf,S
James if, Hoore
John Deere IIorfcon
l.$orks
IIortcon. I./t_co,stn
TIE APPLICATIONOF TIIEFIIIITE
ELEIIEIIT
IIETIIDD
TO STUDYIIIG
TIIEPERFORttAIICE
OF I(EACTIVE
& DISSIPATIVEfIUFFLERS
IYITII
ZEROMEAN FLOh'
A. Craggs
Vept. of tlecha,lcal
Enolnoerin9
UnIversltyof Alberta_Ed_ooton
Alberta,Canada
A COrIPARISON
OF STATICVS. OYNAtlIC
TESTIIJG
PROCEI_URES
FORHUFrLEREVALUATIOn|
H. L. Re.el
_(al
ker llanu
facturi
no
Grass Lake, Ilfclllgarl
L)ISCUSSIOR
OF PROPOSEDSAE REC(_IIIENPU)
PRACTICEXJ1;_O/,
I'IEASDRELIENT
PROCEDURE
FOR DETEIVIINATIDII
OF SILEIICER
EFFECTIVENESSIN REI)UCIRG
ERGIREINTAKEOR EXtIAUST
SOUrlD
LEVEL
Larry J, Erlksson
RaisonIrtd.strles,
Inc.
Stoughton, Nlscons|n
A TIIEORETICAL
EXAHIf_ATION
OF TIlE RELEVANTPAR/_flETERS
FOR
I)VIIAIIOHETER
TESTINr,
OF THE 2-(_TCLE
ENGINEMUFFLERS
ProfessorG, P. Blair
PepartmenLof _lech_nlca]
and IndLas_rtal
En91neerln
9
The queen'sDnlverstty
of _elf_st
397
4Ol
417
435
449
PARELIll
SCUSS[01(
49?
LIST OFATTErlDE£.S
547
=.
t&
IL:L
,,w
(i_._i_
r_cw_'
UNITED STATES ENVIRON MENTAL PROTECTION
WASHINGTON.O.C. 20400
AGENCY
August 16, 1977
SURFACE I_{AHSPO|_TATI(3H
ETJIAU_ SYST_
HOISE S_MPOGIUM
Sponsored by the U.S. Environmental Protection Agency
Conducted by the Environmental Protection Agency
and McDonnell Douglas Astronautics Company at
ilowsedJohnson's - O'Ilsre,Chicago, Illinois
on OctoDet Ii, 12, 13, 1977
The U.S. Envlrons_ntal Protection Agency/Office of Hoiee Abot_nt
end Control (EPA/_AC) has initiated studies [_r_uant to requlrem_nts
established under Section O Of the _IolseControl Act of 1972 which may
lend to Federal rec_lirernenta
for the labeling of aurfac_ transportation
vehicles
_nd mufflers with respect to noise.
One study is designed to e_sess the methodologies available to measure
and communicate the noise reduction characteristics of surface transportation vehicle exhaust syet_s. The informetion c_m_mlcated may be
actual sound levels or Infotmatlon Ielative to sound levels (i.e., verlflcmtlon that a vehicle with a pattie%flata£tennarket
muffler installed
will meet an applicable standard), or other Inform_tlon such as warranty
clsi,_, proper maintenance and operator instructions, etc. The information would be used by dealers, repair faoilltlen, enforcement personnel
and the general public.
The other study is to exploteoswnues available to coma_nicate to consumers the noise dmracterlstlos of surface transportation vehicles (e.g.
total vehicle noise, interior noise, etc.). This second st_ldy,h_ever,
Is not the subject of thls _ymposlum.
In m)pport o_ the exhaust syatelnprogram the f;PAdealres In_ormatlon
on Possible testing procedures which could be used in a Federal muffler
l_bellng requlr_nt.
F2h needs to know whether standardized procedures
exist or con be developed that can be used to characterize _ffler perre,manse without having to test exhaust m]at(m_ installed on the vehicles
for which they are intended.
To g_in the necessary information, EPA is sponsoring n three day symposium
scheduled £or October ii, 12, 13, 1977 in Chicago, Illinois. Inp_|tsfrom
Irx_ustty,research organizations _ed other interested par_les are solicited
to provide inforl_tlon to the gov_lm_nt on appropriate procedures.
I
Iv
Papers submlttnd for presentation should be dlreetc,_primarily to bench test
procedures and their relationship to total vehicle sound level m_thodologies
for use in a Federal regulatory tegulrcment. The methods dlscussc_ may
include the following:
o
o
o
5ystem testing using a standard sound source,
enalytleal simulatlon techniques, and
combination of testing and analytical methc,/s.
Information that _st be developed on veblele or _ine
sound
characteristics (other than total vehicle-no---Ise)
to _iko muffl'erlabeling
u_ful _ould ales be aOdresaed.
While the prlma_, [x_rpo._e o[_ the efmposium is te assess "l_nch test
m_thodologies" and their use in a Federal regulatory requirement, it may
be necessary to address other testing m_thodologies, in the event that
a suitable b_noh test meth(x}ologydo_s not appear to be available. In
thls light a limited n_m_b_ro_ papers will be _ecepted on stationary (near
field) and dynamometer test m_thoOs, results and their relationship to
moving vehicle nolae test _thoda.
SIx aeselons of In-Oepth p_p_re _a planned to c_vec all aspects e_ e_haust
ay_t_ b_nch testily. _]ree planar, sessions will be held e_phaei=ing the
appllcat_on of various _snst
system bench test methods.
Mote Information
lily
be om:atn_
froml
Envlronmen_alprotection A_ency
JohnThomas
O(_ice of Noise Ab_tm0ent
_m4Control (P_471)
Environmental Ptotechlon Agency
Washington, D.C. 20460
Tell (703) _57-7666
Mc_nnellM3ou_las Aatrsnautlcs Co_
_. T.Odds
McDonn_ll-Donglas Aetronautlca Co.
5301 Boles Avenue
Huntington Beach, CA 92467
Tell (714) 896-_412
Abstract O_ pa_ers shonld b_ submitted to E. T. OdOo, _AC
September 19, ,1.977.
Room ecco_mDdatlons can b_ arranged
no later than
atl
Howard Johnson's - O'ilare
10249 West Irving Park Ro_d
Schiller Patll
Chicago, lllln_is 60176
Tell (312) 671-6000
_,, ,,
'[
2
(_,._,_)
_(_1L_
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON,
D.C. 20460
TIIESUAY
IIOCTOBrR
£J'30 - 9:30 (litre
9.30
Reotstratton
Openin9 Address
EPA. kla$1|ington, D.C.
SOUIIDGEtlEI/ATIOllBy AII IIIT£RIIALCO(II)USTIDII
EItGIflEEXIIAUST
A. J. Uramaer_Ilatlonal
Research Councilof Canada,
Ottawa, Canada
(Paper not available)
TEST PROCEDUIIES
_llO EXIIAIISTSYSTEtl
FERFORI$_tICE
PI(EDICTIOffS
P.O.A.L.DaviesI.S.V.R.pUniversity
of Southarnpton_
Snnthampton, England
Z:O0 pm AUTOIIOTIVE
EXIfAUST
SILEIICER
EVALUATIOII
Di_lght
lllaser,
GeneralHotorsTccbnlcalCenter_l_nrrenp
lllch.
TIIEIETfIODOFIIEASUREHENT
FOR EXIIAUST
SYSTEII
I_OlSE
Illneichl lnagawa, Iittsubishl I1o¢or Co,, ilanngawa,Japan
NETIIOI_
AtIO
APPAI(ATIIS
FORHEASUI(ItlG
@IUFFLER
PEllPORt_tlCE
PaLer CIleng, Sternco/If9, Co,, Longvlew, Texas
CO('IPIITER
PROCEDUREFOR ASSESSIflG
IIUFFLER
PERFORIIANCE
I)olmld E. IIaxa,University of Hlaconsln, J_dlson, kilsc,
klEDIIESUAY
12 OCTOBER
V:30 - 9:30 am
lle9tstraLion
IEtlCH TESTSAIIi) AIIALO_SIHULATIOIITECIIIIIQUESFORIIUFFI,Efl
EVAI,IIATIOI#
Cecil Sparks,SouUn:I:sLresearchInst.,San Antonio,Texas
_l
I
g,
CO_IlEflTS
Ofl EVALUATION
TEC/f/IIQUES
OF EXIIAUST
SYSTEI.I
IIOISE
cOrITROL
CIIAMCTER|STICS
D, H, Rowley,DonaldsonCo,, /llnneapolls_
Hlnn,
vl,
I
b
3
OErIEIITESTFORflAPlOEVALUATIOU
OF IIUFFLEffPERFORrlAMCE
Andre_ S, Seybertj Untvers]ty of Kentuekyo Kentllcky
ArlALYSTICAL
ADO EXPERIIIEIITAL
TESTXIIG
PROCEDURESFOR QUIETING
T_IO-STRDKE ENGIRES
L).llargo]ls,
Unlversltyof Ca]If.at Davit,Davit,Calif.
2:O0 pm
POWER OR PRESSURE - A DISCUSS{OR OF CURRERT ALTER{IATIVESIll
E.DAUSTSYSTEI4
ACOUSTICEVALUATION
Larryd. Erlkssen,Re]sonIndustries,Inc.,StouDhten,lflsc.
A COIIPUTER-AIPEU
APPROACII
TOWARDPERFORIIARCE
PREDICTIONS
FOR
EIIGXIIE
EXIIAUST
I,IUFFLER
John _. Sneckenberger,
West VlrglnlaUn|versity,
llor(]antown,
VA
I]EVIEW
OF IflTEIRIAL
COIIIIUSTIOD
ErlGIIIE
EXHAUSTIIUFFLIIIG
tIalcolm
J. Crockerpllerrlck
Laborator|es_
PurdueUniversltyj
Ilest Lafayette,Ind.
SIIOCK
TUllEIIETIIODS
FOR SIIlULATIIIG
EXIIAUST
PRESSUREPULSES
OF SIIALL
IIXGHPEIIFORIiARCE
EtlOIDES
D. Sturdevant,CaliforniaInstitute
of Technology,
Pasadena_
Call{,
TIIURSIIAY
13 UCTOGER
_J:3U- 9::I0am
Reglstratlon
9:30 _nP COI(RI_LATXO{I
OR IIO,GETIIEER
IIEIICll
TESTS AGD OUTSIDE_IEASUREIIENTS
FOR srloI#,IDUILE
EXIIAUST
SYSTE{IS
Jean Rtchols, IJolr,
bardier ResearchCenter,Valco,rt,Quebec
A flETIIOU
OF _IEASURIIIG
EIIGIIIE
EXIIAUST
llOlSEIllA flYR/VIOMETER
ROOII
James W, lleorej
JohnDeere,llorlcen
I;orks,
llorican,
IVlsconsln
TIIEAPPLICATIONOF TIIEFIIIITE
ELEIIEIIT
IIE'rlloI)
TO STUI)Y
TIIE
PI:RFOI(flAIIC[
OF REACTIVE& IJISSXPATIVE
IIUFFLERS
WITII
ZEROlIEAll
FLON
A. Crag,qs,
University
of Alberta,Alberta,Canada
COIIPARISO{I
OF STATICVS, DYIIAIlI¢
T_ST PROCEDURESFORIIOI_PLER
EVALUAT{ORS
W, Roncl,llalker
IIan_factnring
Co.o Grass Lake,lllch,
IIISCWSSXOR
OF PI{OPGSED
S.A.E.I{_C(]IIIIEROEO
PRACTICESJ1207
IIEASIIREIIEDT
PROCEDUREFOR DETEI;IIRATIOfl
OF SILENCEREFFECTIVEIIESSIN l_ElIUCIIIG
£OGIIIE
INTAKEOR EXIIADST
ROISE
Larry J. Erlksson,[Iclson
Industries,Inc.,StrIuqhten,
Hlsc.
;
vll
2:00 - 4:00 _n
I)ArlEL
DISCUSSIOtl
CoJltrlbuted
Paper- Unableto AtteJ_d
A THEORETICALEXA_IrIATION
OF TIIERELEVAIIT
PARAIIETERS
FOR DYrIArIOIIETER
TESTIIIG
OF ;_.CYCLE
El{nixiE
r.IUFFLERS
ProfessorG. I'.B]alr,QueensUniversityof (_e]fast,
Belfast Ireland
rl
i
vlll
OPEIIIIIGADDRESS
SURFACE
TRArlSPORTATIOll
EXIIAUSTSYST[!tS
rloIsE SY_,IPO
s IIJP1
by
Ifllliam
E, Roper
U, S. _nv_rollr_ionta]
Protect|oaAgency
It Is my p]easureto welcomeyou to ZPA'sSurfaceTransportation
EzhaustSystems(]elseSymposiumhere in Chlcago. Thls Is tilefh'st
nmjor actionEPA has undertakc_+
throughthe]abelillci
relatedrespenslbIIitlesof theAgencywith regardto systcsts
and componentsused to
a largedeuree h_ the surfacetranspertatlor_
vehicles. In the past,
EPA has set legalnoise standardsformediumantlheavy trucI:s
antlhas
reccrJtly
proposedttoise'cmIsslm]
standardsforbuses, tr,cl:-mountcd
solld waste compactors,and truck-mo.nted
rnfri(Iorat]on
units;in
addlttonto a nllmber
of other standardsapp|fcablete non-surface
transportation
type vehtc]cs. On al| thesevehlc]es,theexha_tst
system Is one of the Importantnoise sourcesand in some cases tile
prhlcipalsourceof noise. TllrmLqhout
the ]ireof a vehicle,components of tileexhaustsysCcm,particularlytile
mufflerand portionsof
tile exhaust tubh19are
rell|aced
as a rmitlnemaintenancepracticeon a
cyclicbasis throughoutthe osefullife of thevel)ic]e,l+ecaLnse
of these
cl|aracterlstlcs_
vehicleexhaust systnmsappearto be a good ct_ndidate far consldcratlonhl a Federallahelln9l>rouram.
i
_}_+v+.++,_._,+. ' ".,+.v,,G.'.+:.',
"+'+_+:+'-+-_++'_
...........
•t
+
+
,'
'.............
_'-++'+"
+,_+m
.-",'
CX -J
-,:++ +or ,+_.d,i+
EPA has alreadyl_,pluJ:_(_J_tud
{ts guneralpolicy on l_o{
se labelhvJ
and recentlypublisheda noticeof proposedrulemaklnglayingthe criteria
far such action. The specificobjectivesof EPA's labollugproqram
in the noisearea include:
(I) Providingaccurateand understandable
informationto product
purchasersand users regardingthe acousticalpurformal_ce
of designated
productsso that meaningfulcm1_parlsons
could be made concerningthe
acou_tlcalperforn_nceof the productas part of the purchaseor use
duclslon.
(2) Providingaccurateand understandable
informationon product
noise emissionperformanceto consumerswith minimalFederalinvolvoJnent,
(3) Promatlngp_ibIie
a_'tareness
and understanding
oF env|ron_lental
noiseand the associatedterms and concepts.
(4) Encouragingc_'fectlve
voluntarynolso ruductionand noise
labelingeffortsQn the part of prodoctmanufacturersand suppliers,
At thistime| our studyeffortsare directedprlr_rllyat the assessment of avallablemoasurmmentmethodologytechniquesto adequately
def'Ine
Qxhaustsystea_
no_se performance. Clearly,the developmentof an
o_ceptablomeasurementmethodologyto be used to detorLflne
the approprlateacousticperformanceInform,aLlen
i$ centralto being Able to
properlylabelAn exhaustsystemor exhaust system1
c_mpnnent. To assist
the AgencyIn carryingout thls task,we have contractedtiwh Ilcl)onoe)]
UouglesAstronaotlcsCompanyto providetechnlcalsupport in this specific
Area. A portionof tholr contractcalls for tl_ assessmentof oxlstln9
I,
2
alld proposed total vehicle
sound tesLin!l i_]othodologius to report on the
status of current muffler
labelhHi required by |:ederal_ Stated or locQl
regulationand voluntarylabelimlprogronls,
developnlent
of a general
description
of the currellt
aftermarket muffler
industry and to organize
and qsstst tn conducting this sb_posfumof achno_dedg_d muffling
expertson the feasibility
systole
of usin_Jnlethodologtes other than hose-line
total vehicle soundprocedures for uvalnatJegexhaustsystem noiseperformance.
_le recognize 'that the area _e are about to emhark on |s one of m_ny
technical cutup]]ca tIorls and has equa]]y s|zable
tions
In order to effectively
or user.
Tile Initial
Orovhle simplistic
specifically
hfforn+ntJon to a consumer
step hollever, pan,lies the develo_ent
able _ea=(_renlentnletllodology to identify
exhaust systms.
cor_TrlUntca
tiOII Co,,
,;"1 |ca-
the aco,_tic
performance of
_he sX_posJumfor tile next throe days is designed to
focus on this
Issue leith porticular
of" bench test procedures and tholi" relationship
level methodologies.
em(d_aslson assessment
to total vehicle souod
The methods that will he presented end reviewed in
the followIn_j throe (lays will
include hat not he lJmtted to: fiysten
testing us|n9 a standard sound source, analytical
and combination of testin_ and analytical
For the next three days, _.lewill
so_neof the best expertise available
a constructive
of an accept-
sle_ulatiorl techniques,
nlethods.
likely
hove assembled in this rum
on this subject.
I hol_e that through
and obJecttw: Interchange of ideas, t:e as a group Illll
able tu focus on the Issues and develop specific
be
recon_endatlons for
testing of exhaust systenls that can be related to total vehicle sound
levels and have potential
11
use In a Federal rooulatory
labeling program.
IIEHCHTE_iTPROCEDUIIESAND EXIIAU_T5¥STEH P;':£1FORHANCE
I'RE_IC'IIOt_
by P.O.A.L.
DAVIES
,_D_RY
Thim contr£bu_ian
A rational
approach
on stnc_c
tcat
qttnnclCativt_
rcvicwa
cha prc_cnc
Co exhaust
of
of
dcvclopmenC
ay_tcm pcrlo_m_nco =valuation
bcd mcn_urc_ncnC¢.
nndcr_cnndinB
atat_
_Jia
dcpcndn
ch© P.cncration
o£
hawed
on a
primarily
rind propasncion
at
_onnd cIlerSyin dutch which arc carryLnS a hoc, hitchv©locicy nat
£10W,
Elcwncnca o/_ ch¢ approach
_'or
chtti'4cL_rl_[t3R
£or
4dcqu_tal7
appropriate
_otl_'ce_p
cha
modclling
precaution©
are
dc_cribed
nn_tlyt_C
thQ acoustic
£or
©quiwlent_
to output.
reacriv_
comparing
i
experimental
mathnda
o£ _yntcm
inter-component
rnl_tinS
A u#o_ul
in
co_poncntn
s
interaction#
ttrm_ o£ Crantfar
the pr_n_ur©
ransn
of linesr
nyntem component= _,_ d©#t:ribodo
bench _aa#uremenCa
ae_ o£ practical
1
I_cl:hod#
aLcuacion_a whet= nourc#
than=
Component _odQla Ar_ ©xprtaacd
input
lnclud_
#yaccm
can hc _InporcanC,
_ntmrAction_
or their
or
bchaviouc
ca=caning
and a ¢chcm_ £0¢ Ldcntl£y£ap_
which
with
prcdiccioas
_nalTCic
5
_odel#
at
for
Exaraplcl are pra_c_c_,d
for
Che U.IK. ql4iat
ay_ccma tncludin8
_trice_.
m_d volum_ velocity
t rcpranentttLva
liter}'
Veh_cla
Project.
BEt;CIITEST IHIOCh'I)URESAND EXItAUST SYSTI'tl Iq'](FOI(HAtICE I'REI)ICTION
I.
INTRODUCTZON
A aystcmatlc and rational approach to tile
control of piston
cntllnc
Inr_tkcand exhaust nola_ rcquLre_ a quantltar:_vc_pacificatLonof chn
silences//rcqIJircJ_iclltU_
w_th n procedure for the quantLt_itivcevalua_lon
of uy_tc[,acountlc and mechanical pcrformunca.
Thi_ contribution reviews
tha prc_cnt _tatu of dovclopmcn_ o£ such an approach _hlch iu b_ed
bench tc_tlnfi.
on
Such tents concern pr£1narilytent bed i_enuurc,lcntu
wlLh
a _utmln/i¢nl;ln©,but uom_ of thu details required £or r_odcllInll
_yntcm
elements and their behaviour have bccn provided with special cohl flos¢
rLg_.
_Je prcdlctlon of nyo_cm pcrforrn_ncouuually concartl_{:hecalculatlon
of tlm tr_m_por_ of acoustic ©nc_r/_y
throulih_ho _syattmfrom the _ourc¢:
_o tI,_outle.twhore, it _n r_idiatcd, Ill. For this.on0 requires a ucc
of rnod_lawhich de_cr/b_ th_ acoustic tranofc_rchsroct_rla_/.coo£ _ach
=y_©m ©l_menc in qunntita_Iva tcri_a 121_ with
.n analytical procedure
for colnbinLn_the =lement= togcthar to da_crih_ ¢ha ov©rall tranapor_
o_ eoc_r_ythrough
dascr/bcd
/_n ©l©m_nt may b=
th© comp1c_t=i;ystcm12. _[.
as any part
of
th_ duct
_yatcm
propoSal/on
of acouetle
w_v=a (or _nntgy)
connac_lon_
the =n_/nc.
n©ction_
that
has
through
an aff_ct
it.
on
Thtm.
o_ cozmact_n_ pipa_
tll_
in thin
th,_ ope.n ¢Itd o£
the
ayst=m and nny duct discontlnulry or mu_fl©r co_poztcncara all acouatlc
._Llencing
open pip_
noise
_pe_rl condition_
with
tha
deecript£on
properly
t
r_quLram©nta
_rn normally
mc_nurer4ente,
o_ tho
statutory
or
o_ silencing
©valu_ted_
coverlna tim
en/linn.
_p©cif_cd
also
full
note_
1imLtn
If
by first
operational
Thin /nform.tion
r_quirc_nentn.
th_ 7 can
d©tarfalncd
p_rforrainll
loml
to provida
_ qtmntitntiv©
the open pips dnc_
b_ unad to d©_cribe
and
can th©n b_ compared
nra
the acoustic
_ourne
point lot the qu_ntltnglve _vnluatian of th_ Inl_c or ©xhaunl: nyotem
chnract_rLnt_tce
o_ th_ angina.
_ia
tnformatio_,provida_
a ntartin}l
_couetLc performsnCao
Thus open pipo meneuremcnta
with a loaded ©osin_
ropra_ent
ono _¢santlnl
_,,._._...-'_.-'L_5.i_-.w;.....Z_.a._.,,
.. ,:
par_: oI
th_ to_l: ptoncduro.
7
................
....... o.....................................................
.
, ,, : ._-,:_,:._,_i
_
Acou'JtJc pcrfonaancc
los0.
open
plpc
and
No_e
tha_
thi_
remains
_icn
cmi_tcd
definition
chc
thla
ayt_tclai
of
acoustic
bahnvio.r_
louu
depending
on
aloha
their length.
exhauut
and
_ILi_ then
For this
o_ che_
in
included
int_k=
cnfilne
thu effect of
the
co_t and
wcight_
control
noJao
Inscnlln_ion
_Iowing
on _coua_ic
Y.rthonnor_
a_l¢l ill
hot
so significant
tcp_p_ratnre gradlcnt_
cngln_
(or
v©|licl_J sp©ed
and
op_rnr.lonal
and
gas
prcdictlona
and
_u_flci=n_
co_ver_cd
_y_t=m_
I:ona
to
Thn mann kinatLc
nc_w nourc_
app©a,rin8
compon_nc_.
system
aoounl:io
_lthcr
Fioally_
tom[.
bn re.d=
rnu_t
t'or
thl=
cn,;r_y
at
ncou=_tic
ca=ray
a_
broadband
_lo_
charact©ri#¢[c0
i_ good
may
6 thl:
durin
I:|l¢ gas
tlo_
within
the
no_©_
_r
=vht_nc_
chn
an
[5[
_or chris
l,_rforlnanca
during the
_mbl_d
al_o tnodiL+y
,_ziat which
DII_ allownncu
purpose.
of
tilers
pP,rfo_manc=
=_|_ficiently rapidly
per_nr_nc©.
chnng¢_ wlCh
data
con_trnlnta.
annl),_i_,
_|l_ _X|l_tli'_l:
factors
sd|:qunt_
to provldc
n (lir_c_ c_ff_c_ on _cou_tic
=£f_c_
_low
Other
the _y_tcm OOl.pOnCnt_ to
_
_nd ©xhn_lnl: 6n= i= nonoally
a =lani_ic_mt
+rod _ficicncy.
power
dh_erzslonai or o_har
hav_
con_Idaration¢
_o haw
form'J I.Jrt
rc_son trm_s-
or c_]intl_t _ystcrllcolnl)oncnt_.
pack._Ing
tr+zn:nnl_aJ[on_
to _it in with
_ea_t_rementn.
m
m
_yutcm on
_:ncCors Includa'thc
Th_
a clc_irly Identiflabla
[mr/or_r_nc0 can be a_t#e'J_cd in tc_nn o_
flanking
duct.
the l;cctlons of pipe
ia not m_ approprl,ttc pr_tcticnl t;_ethodfat dc#cribina
and
b_
l.wc
|,||that th_
rclatlvc
or inlet
sines
rc_pon'_© of the rm_fflcr unit.
t|l_ In_nk_
durnbilicy
the exhaust
the ayntcra each
m_chnnlcnl
minlm_=a
ir_fluenccd by the
i_ well under.toad,
comnponcnts of
H_chnnical
thin
i_ duc
the source
r_odlflcd, It ia well e'_tablished
cnn be strongly
happen
|ha |or+called
muse
dlffcrence
in tile sy'Jtcm and that
t|l_ aco_£_t_c p_rforfnanc_] o_ in_tkc
=nd
emlttcd by _£n
intal_c or c_haust.
asz;urm_'J
th+it the observed
the |hufflet unit along
should
connactinll
,
of insertion
l_res_urc |evcl b
the noi_e
by chc _i]enced
a mulflcr unit
per/at|santa
poaitlonlng
Soma
terms
unchanged.
observed
mi=slolt
rc[u_t!ncc po[ntj bctwcvn
the nolsc
to thcpret;enccO£
of
in
described
T]li_ cnn bc defined _i*Jthe dlff,_ruilcc in sound
incasured ztC n fi×cd
That
is generally
may also
;[lltltkn
b=
or CX|laUnR
rcg_n,_rated
tha_
cnEin_
char, fit=
bre_thins
_ngfaao
I
char_ctnrintics
i.
and cons_quvncly
_he ncousr.lc
sot|re©
acr=ngth
o_ the
pt;_a
in
for
_[_
_FOC_C_U_'_!U
_l1111ZIH|ryD _11C
for
iBto Im set
of study 41rensp x_alncly:
_l)
Hcthodu
b)
The
specification
for
measuring
c)
The
/tuIJe_slueilt
and
o[
of
e)
A proccdur_
for
api)ropr£tttc
de_criptlon
tile
for
knawl_dge
ENERGY
associated
::o snecify
o£
elementu
the
nystcta,
flow
or
internal
inu_l'_tll'utneBt_
o_
or
together
to
provide
including
all
the
predletinlI
or
detert,lnlng
an
_tn;llyni_.
_m
iutcr-
tcchn[quea
to
identify
can
ovcr._ll
problc,na
interaction.
conaldercd
cxpuricnc%
in
d_ncrilm
botlt
=olutlona
terms
_lnd
,
lit
the
_ndlcath|g
bc
light
the
pur£ormcd
.t
tile
of
level
cutrel_t
of
prese:_t
con[ldcnce
time.
I'ROPAGATIOII IN FLON DUCT_
the
with
a_mpl_t
aIRI boundary
be
ilow
_ht_t_© _lt_
ve.locity
in
tcml)erltturcs
charactet'iutics
pet'fOrlntlliCt_
for
nynte_a
_:valu_ltio;i
cqllflt_on_.
at©
o[
will
propngatLon
and
enact
rclatlvc
_,1/_
transfer
the
lncludinB
t_ourcv
practicnl
the
momentum
thca£r
_ource.
nle_r_ellt_.
f_ctor_
and
which
Sotmd
In
;icoustic
their
,_lld
collstr.l_nts
oll
procedure
from
of gbc_n
motion
I)nscd
l)erformanc_
arinin_
1_1_
wltll
_]OW
,coustic
tls_cmbl_nll
bctt_een
_yagem
the
elements
An appropriate
ACOUSTIC
Eiltt
sp._ce
modelling
nytltura
llCt_OllU
with
IlerfOl'lD/lllCl_
generation.
Hcthodz
E_ch
the
faetora
exampl%
d)
£)
_y_i[t_m
rcquiru.mei_t:l.
operational
pcrfo_nlll_c_#
noise
iH|d
can u!;cfully bu subdlvidcd
ch;lracterlslug
silcnclntl
For
[e_t_.ll_
control
inlet and cxl.iust nolsc
[tlCclllln_cJ_
i
bunch
prediction
/_lb'niflcllt|Cl-%
2,
_or
and
can
the
b_
acouatLc
he dencrilmd
can
Oil Coll_etv/It_on
of ncolmttc
t41tvtl I_Ot_OB
In
obtained
b_havlour,
conditions
for
Ilowcw=r,
ttm_sminnion
_orm
of
po_£tlon
in
the
flowtl
nnd
thene
rentrictiono
rllBgc
O[ dtleg
in
rt:main
nolut£on
con,idcrat_onn
dincontinuttiea,
tl,:
Iql_ll
if
the
ttlld
Ill,el particln
n comprchcnufv_
_l)_:c£al
at
l£uear
O_ I;liltl_lI I:[lerSy
term.n
I_mnt practical
by
pr_unurc
to I)_ on_-dJ_tucn=ionnl.
condLtLona.
obnerved
Iltltlctl
vnritttlon
perh.spn
n_umed
ducta
to
thn
duct.
W/IV¢I
lieometry
r©nliatic
may b_. n_cnnnary
an
wLll
he
"_hown latnr.
Etnptricnt
d_scriptions
whorn, ay_ter_ element
can be tim
caue_
with normal
lined
.ith
COll]lllll
S
an .all
Pi_nt
a_ flow
mr,serials.
noioe.
way= propagation
c rtlAtiv=
.ourc_
of
r©[l©ct_d_
to thQ Sat.
c,n d_.ct_b,
through
orlflce_
tran_lain'Jton
_tlong passages
include
flow-acoustic
flow,separatlon
or edge-Cones
ouch behaviour
i_ by a .avn
ell.
preinurn
w,_w by
which
th. duct.
_xcit©J
are
nl_o
mechanism, the
cnerBy
thQ w_ve motion.
©:lerS_ ia t_n_rnitced
bo_h wnw=
Hith
k + th_ u_v_
ct . coaf£ici©nt
eravallins
AC tacit
n_ a nnw t4/lv© t||t
with
n ph.nQ
on=-dim_noional
Why© ptopn_l.Cion
p+ at,,| pnr_iclt
v.locicy
v ÷ in
v©loci
W
in duct.
thn po_itiw
m
"ax
pr_=aur.
numbar
r©prossnt¢
Similarly
p- '_ p'ctl'(_t+k-x)t
,
,
}
2.1(.I
2.lCh)
_ndv=loc/ty
_mpl/_ud..,
_ St1. rnd/an
N/(c+II) m 11 t:h_ thegn I_Iow velocity.and
of wnv© an©rBy at it
c|itdecay
th.
r_fl_cted
ax
_
^- ni(_t:¢k- x
v" ,, _
),_,x
'
Such
duc_=
*om¢ of th_
b©i._
whir. p+ and v + arcs th.
"
Some exnrnpic_
which
p+ " _+_ti(_t'k+x)_
" ?.
.Ions
with
necessary
behaviour.
trZlllnla[_'JloiI
sound
OLher .×ample.
propagation
b7 .
goin_ (incid©nt)
lr_quency_
acou.'ztic
a.'_tmclated
In flo_
cr_rSy
di0continulcy
_c,naind_r
with
or with
become
non-linear
later.
Acou_eic
on.
flowj
per£ormancc
a _trongly
exmr,plc,
abaorbin8
bainB provid©d
duct
for
or grn_ing
and alnplific_cion
con0idcrcd
2.1
o£ ncouutlc
exhibit,
w_vn iu ,l_acribed
prop.satan
by
2.2i")
,
;L2(h)
whcrn k" - ml(c-U).
An .lt_rna_iv.
demcripcion
_. to _xpr©a= _hc pr_ur_
_c b)" p+nim:_ "Tx,
where T _"_+ _[[_.
}4i_h hard wallad duels a._o add fl,tk+ uhila
thn duc_
lmpedanca
Z -pc,
The sound preonur,
the
characteriatic
and par_iclt
_cnuuttc
velocity
imp_danc_
nC any point
ot the
n_
S"*.
then girth
by
p . p+ + p'_
2.3(a)
v - v + ÷ v-
2o3(b)
To represent diacontlnuLtlcsp one first notes that some of thv
incldunt waw
cncrsy will bc re[lactealand tlomu[:ranmnit_ed°
The
rarlo(u_unlly comple?O o£ [:hercflcc[:cdto incldenc wav_ _llnl_li[:u_le
J
[:urmed[:heru£1cctlon coefflclenc r_io c_pres_cd by
P"-
Z_- Z= . RQi_
ZD+ Zo
2..,'_
wizen [:he boundary condJ[:ion=aC the dincon_InuLt7 are =pcclf_cd aa
an hnpcdanc_ Zo
For an epe.nend, the phnna nnglc _tcan be ab_aln©d
J_rom_he aolu_ion glv=n In 16J for zero flow.
The appropriate vahm
o¢ R for varloua flow Hach numbers O/c can be found in ilia
relation=
for
n baJLfl©d openins
can be found
in
Similar
171.
_/©ll1©c=_ng|for
uimpllclcy_[:h=a=Cenuation along th© d^uc=with 2,4
de=cr/bin_
condir:io_a
a_ xot [:hen [:he prea=ure ampl£tude Px at _ny
o=har point x in n pXain duc_ i= _£van by
PX
^ M Po (e'ik+x
where ka - _(k+ + k').
+ _at_©Ik'x)
!
- _/C(I-H2).
_;i.
ehowa that [:had/atone©
between l:ha nodea o_ the _¢andlng wavaa i_ r_duced by _he factor_[:h
£1ow pra_enC_ aomparad I:o oh= zero
OJ__1o_' mod_£ea
!
aleman ill)
2,2
flo_
ca¢_,
_lm_
(I-H2)
=he exia[:=nce
=ha ;,requenclenat which Xe,
nR[:lmoJ[ duel: (and oZ:her
I_e_ona_,
AcouaciC Conaervat_on rela_Ionah_pn for._IO_ duc[:a
Nich plane _vae
escla{ie4
in a _ni£orm _Io_ duc%
12] i_
_hare A in _ha 4uc_ nroa_-_ac_ion
area,
conservation oJ_ma_a _=
Silnlblrly
it
con_ErvnLion
of
cml
be
energy
=hewn
iu
that,
for
_ntlsfled
i,JunLropIc
COllditions,
i_
(Z+H)_÷ + (I-H)[;- - a con=Umc.
Givun
a uni[or_u
only, can
duet
51101-/that
non-dectlying
woven
%.,
p£
The
oE length
iu
oe(p
r_.lt
tc_p_rature
duct
wall
Po_" and
of
hera.
length
cm|
Iaccor
©n_
the
with
.
.
i_
duct
n_ction
ero._
nnd
b*
121.
reprenented
and flow
l
L
can
by
proparti©n
well do_n_trem_
an_ can n_t ot_t
Iiowuvarp
in
n loal
b=for_
£nctar
the
_|I_
by the ¢ub_cr_pt
the conditlann
chambnr_
(but
for
n*_
2 nnd nEBI©ct_n
conncrvatton
J.2
that
_ntropy
I 1).
by
F and
the
by
a
/_ch
No.
£1OW In
tl|_
r.pid
g|l_
conwniently
ol_ 2./]
chanson
=to.
along
_o on.
mignl£leant
Ir_quellc
thn
n
£rom
of
anntnnption
eon_©qu|:ne
dl_continuity
and
t,_d_
on
tll_
r_qt|ire._
c_n
,lucre
nc
howev¢r,
a.
in
I_
cOl,l}One.ntn
be H_eeified
both
Eap_naton
and th_
lo.=Ean
two
1)© Evnlu_t_d_
rJght-hnnd
p.rtic.larly
occur
i_
of
H.
cllnr.ccerl_ica
tim
b_ _atabli_hed,
Flow
then
nyntt:m
_'_nd
oB_ alllO
into
7.0 cnn
,l_,p©ndnng
r=aHntic,
=hn_
chnraegEriaticn
r_f©rcnc_
.
h_r,lly
can
mcnsurel_enta
k*_
_-h¢ wt{v¢ mnplitud=
Ag dincontln.LtJ.eu,
tnantroplc
Zg
of
include
dc_rnliN_(|j
n,ultJplying
n ne_ativ_
l'cl.tionullil_
)
_valt_
impcdnnc©
of
+
d{Icomponed
Zoj
modelling
included'by
or
b_
for"
by
tO
go
t.l,
flow
2.fl
nEcc_nttry
mclt_tlr_d
,ltnchnrge
transfer
defined
flaw_
Po c_n
_h© decay
b_
i_
Ina_
I 8Lvan
pip=
dn_a.
begin
l_
llow_v©r
op_n
©ntnblinlmd
Po
Zo b_f_r_
Po °
tim
Since
ult_,plc
o£ tI,_ch nul_ber
llnd of ina_
^_ eik't.
Po
often
it
mu_n
flow
cnEr_y
pc(p
tl|at
and
i_rE_tl_
the
+ po)
ind_cttt_n
knowledg_
by
are
a utuady
ncotlstic
p¢ -
,tlld
con,lition_
_low
of
ulltiziEiud
%, -ik_t
pOE
termi||,_tion
'l_lJn
g with
consurvatlon
2.7
in
Th© tr_n_f_
lJn©¢
n_g
ehnnl_©,
D,mcrlhing
_ubncrlpt
otlt
i_
elm
_countic
I
and rhone
B chnngea
In mean d_nzitT,
o_ Inn_n _low_ energy
_lnd
i
,,omuncum flux
acros,
Conserver|on
the di_contJltuity.
of Irl._
iu u_|_rcs_ed by
A÷
^+
A2[p2(l.,2)
- _;(I-_,_)]
- ^i[p|
(I+_==)
- _;(Z-H_)
+ 6_1_].2.1o
while conucrvatJon of cucrgy In t.ltisficdi_
where 7 i#Jthe r_=tioof
£f
©he _pccJfLc ]leltcn.
Homcntum l= conaervcd
- _i'[^|(l+_,,)
_1+ ,,|
[^,(l-_,|)
] + 6^p,=_
2._2
For one-dJlncn_ion_l(lot#,and known 8corn©try,{;heinc{dent _nd rcflccZ¢Id
t.'avsmp_ nnd p_ n_ter '|:h_ d_.continuLW
can b_ fOum| in t¢=_i,l=
o_ the
known incido, c and rcfl©ctml wavcI_bcf0re it. nf_cr th_ unknown loam
factor 6 h_a been clImizu_c©dfrom th© thr_.ecquation=.
chrec._q.aCions c_ltb_ tiS_d _O
area
dfeconc_nuiry.
Other
a =mim{,'lar
nppro_ch.
d0_£11©
Thu= _hcmo
A iron,for rclntlon_hip ,for any
type= of dl=contJztuiW
c_n bc trcnted
One aho,.tld
not= I:h,_t the phamc chsns_a
uminS
occt*'_'Ein_{
arc©urn tlm d_acontlnulCy c_m h,_dcccrmln©d from a non-propa_atinp_hi£hcr
order mode analy.i_for
The m=an ocouatic
_coustic
in_cnsity,
zero _low.=hat =atlmflc= tim boundazy cundition_.
ennray
flux
i= cxprez_cd
per t,nI_" _cca of duc_, or the
a.
where p _nd v _r* the r.m.m, pr©nnttroan4 v©loelclc= ceapccrjvely _nd
Cite overbar
cepre_c_E_
the= bocomc=, u¢tns 2.6
x time _v©rn_e,
]rl Ecru= of ¢||ewnve romp©henCe
and 2.7=
= ..2-_-;_[(z.,_,?
=-,(p't)_.-(1-_0_<(_
)..,.]°
=.zs
:Lylnbol < > rcprc,_ent_
where
the
term
in the
or
th_
brackeCa
incident
_t_aln'Jt
the
while
flora D or etler_y
of
divergin8
givea
I_ith
the
energy
flow
flu_
waves,
oxltau_C outlet
in tl_e tailplpe
Thlu
Tile firuc
flux
reprc_ent_
reflected
by the
energy
wave.
uecond
by the
radiated
the nett
nlezin wduc,
n0 an energy
the
carried
the _ound
by equatin8
apberLeally
interprctml
wave i_otions
Tile level
obtained
cnn bc
Liz]_in_ th_ title
can be
to that
for a tailpipe
of
of
a
r/idiuu
a
_A 2
2
W|lC_ro
Pr
from
PoCo
"'lfl
t|l_'
r*gl,
th= outlet.
£lue_uating
provided
thv
bohaviour
pr_aented
for
many practical
which
oh© d=cay
of
for
th_
th_
of
To cornpl©t_
=om_ _xamplca
aorac typical
5
ar_
ayatcm
ia no_
=l_c:wh_r=
h_r=.
Kradie, nca
=,mall=r
==ctiona
conatant.
diacontinuitiea
enersy
propagation
rn_aaurcd
with
=.nbo o,,ndZ,,
Izl;ll;ll
in duct=,
ch_r,_ct_ri=tica
_low rLlia with
A further
rn_.a=mrcm_:nta with
aeoun_ie
131,[q].
to
tcmpvr_=tur_
into
m_ =ubacantt_lly
the
th©
t_inc© an alL=r-
Axial
ob_ain©d
exnmpl© cnnc=rn_
io no.t r_trictive
prcaant_d
element=
th©
Eamuplea
propugat=.
b_acd on C_nt b©d or fie.ld
The firat
theory.
can bu _xt=nd_d
of acouatic
pr_acnt=d
where
Ila_ b©©n deucrihcd
ncroaa
the
tl)easurement_=
Lh= analyai0
co;,paring
,ll=continutrita
r
known.
charnc_criaticg
_:_atric==
can b_ reBard_d
pr_a_u_tud
di_tltIlc=
to aituationa
n=_,umption
by auh-divid_nl_
thi_:ruview
/I
[it.'ld
are
acouutic
tllia
aound tran_miaaion
on tim analynia
itnpcdanc_
The analy_ia
wnv=a aa thny
tempnratur=
Som_ e,xa_pl©a
that
aitapllcity,
fit
from free
by linear
trlmofur
b= aqcon_odnted
tailpip=
_dJovc io reatrictc.d
applicationa.
uain8
I_lUll/Jurl_d
radiation
indl_atea
r
can bc cenployed to dctcn]_inc
w,_yof ,l_acribinli
Thoush omitt©d
baaed
2,14
in tim
preacnted
approach
may alao
prcaugro
level
can b= clt,_rac'torlacd
only ©f_=ctiv=
2.3
I|COLIUt_C
_lacb nu*nb_r and
_ra
wher_
fl,
Equation
pressure
Tile ,untlyaia
nativ=
pc r
acrie_
_lCllCC_
o_
predlctiona
of cor_Fari_on.n
component= and
'..d I1.
=ne,r_y transport
atro=_
a
I
"]
__
contrnction
which
performed
with
acmz'_tic
_ource.
flow
Nach
and
a higher
ztlro
lleoutltic
Tim
zero
c_nct
the
with
It n.mll
predicts
Flgur_
nnalyuin
for
_ero
plttnta
of
wily© anttlyoin
A _llcond
e.x/lmpl¢
re,=ultn
nrc
conditton_
tile
_pnrate_
_n_lynin
that
_
_rt
_lm
hi_hcr
{Ill
inveatiBntion
an
_ppropriate
'correction
end
o£
just
wall
lit
the
tile
appro×ilnated
by
provides
of
plane
in
wave
the
the
aa
error.
tile
the
seen
ex*leg
correctly.
provideu
of
men be
The
frequency
atlaly_lt*
ttllaly'Jitl
nidebranch,
eaves,
frequency
ten ltdellUtlte
dlt_continuity_
chltrtlctcritlttcn
lind
Figur©
(:its
end
hall
of
2(J)
b©en
t)u_
piptl_
the
wigh
hishcr
order
llow
inod_iled
roodc.t
an_tlyml_
_how()del,st tile
correction.
in
Thi.
n_
thn
pip=
in
thiD
Cn_
th_
tim
Inct
that
A detniled
I101
if
n top
ohow/l
thtt_
otdttr
hltR
cntl
*,nnloS_uz
thnt
nllow_
prcnllur_
velocity
_llnplitud_
and
thnt
thtt
(in_lyni_,
lind
ehnngn
.ho
tilt:
_?tlvt_ theory
hiBht:r
rltdlun
Ill
tt jot.
re, reline
laborlou_
phttun
_llltt
Cun:ming_
I)y plane
by
II tiidllbt'llnch
include
predicted
_)e_tir_tnellt¢
prmlicted
2(|1).
nl_o
by
correctly
Ehitt
t41th
formin_
i}ret, ented
with
b_
lind
inure
tht_
art
0.6
C/tll/intlioQ
dl_continuity
adequately
over
the
tr_m_.nltted
lt11 _tre/i
in
tile
order
plane
rondel
contraction.
closely
that
the
ttmplltud=
tim
pl_lm)
ohnnfie
throughotlt
calculation
woven
clmractnriuticn
eolnpnrinon
are
pilate
tile
three
change.
problem
charaetcri_tina
be
tile
predict
tnethodtl
cll_r_et_ri_6icn
Again
correct
of
cnne_iitl
at
on
for
n eonutant
however
both
phnn_
lift, timed
prolll_.
does
at
thill
aroplitud=
wiv©s
i_
illuntrnttd
boundary
_loW
amplitude
defining
th_
motion
can.or
the
thi'J
_howa
f,icier
trtmn£er
anal_nl_
can
and
itle/l_uretnerlttl
thnre
of
tim
here
;It
The
2.12_
formltlll
intensity
_Iade
flow.
to
condition
plpeu
tnodeuj
decay
_low
a high
wove
zero
were
_igurc.
the
hut
tt coll,bin_ttioll
moda
the
tile
l(b)j
description
the
in
plllne
for
boulldacy
outer
radial
with
measure_entu
2.10
condition
five
shown
the
anttlysi_
and
tnea'Jurelnentu
provided
hy equations
velocity
includeo
correctly
(exact)
inner
first
rig
a_uumlng
velocity
tile
Contpnriuon
which
Thu_
mode
The
pre_;enLo
prcdlctlon'J
pnrticle
I'o_ult
in
the
pltrticlc
flow
l(a)
repre.';ented
betttoen
includinll
cold
Figure
order
_uutly'Jlnj
a nidebranch,
_t 0pecial
nulnberu)
wave
annuluo
ineludelJ
tt uyatenmtie
I)e ¢nlculntud
to
tile
well
il_ l_pplied
I
by
known
for
end
t
predicting
fluid
tile acouatlc
inertia
resonance
effects
appropriate
at
the
discontinuity°
or
cot_tracLions
to expanslong"
in Figure
3.
of organ
'lqm dotted
line
plpeo
to account
The end
corrections
in flol_ ducts
indicates
the
lower
for
are
illustrated
frequency
limit
for
propagating hiKhcr order modes when plane wave analysis breaks down.
It
can hc .qeen
large
area
ration.
_lmy become
for
A third
with
to match
i
which
r©ported
with
th_
velocity
£low rile
¢t u_n£ttl
2.4
Acouatie
ineompl*t_
aourc_
nmplitud_a
in
4.
anlmunt
energ_
unntendy
of then@ prennur©
with
an altcrnatlvt
by Atlara_
Thin
lllu_traten
th_
by dimensional
verier
reaaoninat
a_ 1t5, whatn H in
al: hifih_r
a_
_irinll
the
frequencies
th_ valve,
in
that
the
t©chniqu©=
in flow
alno
an
ntrnnBth
rotational
above.
wher_
tile
flow
would I)n
valve.
high
till
,mind
The:
0,_
b_r_
mor_ ha_onic_
One can _how_
at
any flzed
np_=d.
ptovidt_d by broadband
16
upncial
dcncrih©d
ductn
ont_ cylinder.
"the source
and nt dincontinuit/cn
neck,
Th* primary
at tile
can ha
for
angina
way that
nnd oh_rvatlon_
of th© _ourc_.
ptoee_ann
fh|etulttinnn
fr©quency
in compar©d
of the
whil_ tha £r_qu_ncy npectrum connlnta o_ th_ firn_ lO0 or
o£ tile _undamental
and
In]
within
predictions
l,oden
hltu b_en
ar_a
charact_rinticn
pt.oblemn
order
annuli
propallation
flow
avoidhlg
high©r
etc.
of
n_nteras
without _nm_ eonni.d_ration
by th_
neck,
connecting
tl|= |nodelling
around
advant_q_¢
includinl_
by chan_/n_
h_tween
of
£s wrapped
added
resonator
thrce
neountie
and
o_ ncouatic
renonatorj
the
Flaurc
a:;ra_mcnt
in intake
provided
length_
eha:nber,.
analynia
can b_ modified
effnc_ivvn¢==n
An account
duct
be neglected
folded
a'he pr_dictionu
for tailorins
neuron=
of
htl_ tile
at
tit the
mcaauremcnt.i
the
_1_
lilIlit
the
and could
of pnckaglnE
on ©nd correctiona
The _ood
illu=trat_=
pipe
aa a llultnholt=
either
Ilow
Ix21.
baaed
£aatltr_
plpe'J
geometry
condition_
rc_onann©
constraints.
of
A detailed
Iml|ndn_y
nyntem
aa a percentat;e
convenience
ctoan
excitation.
approach
open
the performance
Thi_
by Cu,untnan,
nimplcr
for
aection.
hiBh
flow
concern,
cnn be regarded
or a _idebranch,
the
calcul.tlons.
exalnplc
thetla
©_panuion
_end to
long connecting
prediction
Effectively
avoiding
corrections
P'urthermorc,
_mttll
in practical
the
tile
tJltlt
Broadband
flow
can
frequency
noiao
noi¢_ 8¢nerated
,eparatn.
Thin
spc:ctrume_llJbltsn fl_t peak at a charactcri_tlc Stx'ouhalmJmbcc FL/U
of around uni,
tys whcre L t0 a c]inract_r_stlc_cnlu of thc *Jo.rcerot;ion
and U the pbane vclocJ.tyof the disturbances at|in8 a'Jsource_.
noi_e will wlry_ at fi_cd frcqucnclco_ au N ?.
No_c
Such
ccncratcd hy flo_
turbu]_nco at _he duc_ wall_i_bcx_dsetc. may al_o represent a ni_niflcant
aourc_ of hlllhfrequency t_ound,
Itu _tr_uLt_rh
will v,lryaa VG_ where V
J.nth_ _)eanduc_ flow velocity.
TurbochnrtiJ.ng
modiflca Chc c_bauuC nolue s_;natur_ .JLnccJ.ct_n_h;
Co rcduca tbo amplItudc of the low frcqucncy coiI;poncnt'n
ar_slnf_from
_atJrclc_
tln_ady
proccu_.
_t m_y add new uourcc_ of coit_Q/;cncra_edby
flow Izltcraction_in tb_ turblnc or blowcr_ by _akc no_
chc blade_ or noz¢Ics and _o on.
T[i_ntrcn_;tho_ _ucb _ourc_
[ram
c_nda
to vary _a Vo6 w|iorcV° i_ t|l_m_n _urb_nc ou_]_c J[_owv_lociLy. Tb_
cllaract_r/_ic _rccl_c_Clcaof _uch _ourcc_ i_hty
bc |_{;I|,o_ thc ot'd_rof
tlla
curbina
blad© pasning
frequency and lib
Tha aCr_nlltho{ chc nourcas a_oclatcd
harmonics,
wi_b the cI;_ne
brcnthln_
of r.ha_urboch_rtic
r caR ba studied and cvalua_cd on cho L_t bed.
Flow
noLne acd ncou_ric regeneration wJrb_itLbe =ailcnc_r_y_tcm rcprc_cn_
a dlff©r©n{:probl©m _ha_ can bnt:tcrb_ _Cu(|Icdwlth _p_cJnl riB_,
Thc_©
latter arc gcn_raiZy lowcr in in|cavity than tbo_a as_oclat_d with tile
cnstna bu¢;are of pracslcal alr,
nlflcanc_ _nca
_hey #_t _n upper llmit
to th© _xlrnpm atc©nuaClon tbnc ctm b_ obtained unlc_n car© i= taken
co _nlmiaa
them.
Flo_ noi_a i_ broad band, generated by flow _cparnclona ac vaIw
U,p_. band_,
axpannlons, concraction_
n;]dby turbu),cncboundary l_y_r _Io_'.
_I:i_ o_ most _ig'nJ,
flc_ncs when an_pllfL_dby cavity resonances,whlcll
plcov/,da
_©cd back _o inccnalfy tli_court©.
iroplnllemen{:
o_ the Ja_ £ormcd at
Hoia_
g_narat;;,on
by the
tb© cbnmbar antrancc an tbu lip of t)m
©_J,CpIpa in n _caa,|yfloatrig in illuntratad in FJ.gur_ _ nnd 6,
Th_
b_o#d b_nd _pactrtunin Figur© .q)im_b©_n _aodularcdby Cttill)/p_
(p_aka)
and chambar
(trougba)
Flfiur_
with pJp_ a©parnCion
and wich
flow
;:lle way aourc_
_trenath
_t
grecians,
,_callngthe mcaauremunu; to corrcspond
Cn • 7_ _ di_m_c©r
_racC_.cala©pararLons Iie clone co x/d - 2_ wh:re Cha ncrcngCh iu
Cailpipa with a _'low f_ch nurnb©ro£ 0.26 at (_OO°Cylaldn a aound pr=n_ure
17
x/d
6 _.llustrat_a
m
_
varie_
raaonanc©_.
wloc_ty.
level
of
05 dBA aC 7.5
toilpipe
b_ '_uppre_.
Fi_ur_
7 indicat_a
a perforated
nren
7.Smra pi_ch
BivinB
by the pcrforata
art
in
flow
m_a_ur_.r_l|_t
acouatic
wart
_1_ aolid
aritticl
lint,
p_t£ormed
by
tha
j©t nolo©
and
In £11rly
and hav_
illuatrac©
(a)
a ralacivff
]tvcla
_o htsh
CO pr©dict©d
berw*en
by fittin_
tallplpt
thin
at
amplification
thn
rc,onanc©
complex
perforated
loyal
_o 160 dB)
in Fisur©
_.rann£©r
d_cribcd
[lal,
but
9.
charntgearlier.
Ila_l l)_©n aeudiad
in connection
eh= mccllttniam.
_h© ruoulc.
oound
layar_
a_
(b)
du_
and
loyola
can
low forcin8
o cloat
fiald+
pot©ntial
nC intt_m0dtac©
at illu_ratcd
Other
(,p
of e.xci_ation
b©haviour
flow ri/_a
atc:td)_
illuatrnc©d
in transmitted
vortax
non-linear
bride.ca
_o
nyat_m.
bccom_a nei_lialblc,
trav©llin_
t|m
when _harp
ay_tem,
to qunncify.
Itwl_
that
anti iadlcntea
m_hod_
by I:be _|l_ar
hiah
RCt_eration
8 uhowa
the atoplittld_
jet
oE th© hal©
bQ acceptedw
it|oh
tn|d©r,tood
difficult
/nor©an©
_rantmi_aion
and th_
Fortunately.
well
h.Smta dimnceer
tone
,upply
ar_
acouatic
_xcit©d
ampliiica£1cn
when th_ /_hear lay©r
£ttld
b_en
ton:
rc_ult0
tile hol_
nc _.Olt.ii pitch
Pitlura
quick
rcprcoent
linear
twice
_hc deeall_
(ll=cr_©
in a _ilcnccr
gin[ll©
of an acottatically
• r_ non-lin_nr
interaction
with
Som_ typical
expnnuion
of
_tcI'o_
5 _o tJ correspond
trt:itted
on kiln £i3ur_
'Flit
behaviour
due
F/Butch
;llld oiitlet
pip_: boo about
D had hole_
tlla_ mtl_
arc employed
i_l
t!alculatad
l.gflln
back pruoaur©
pu[zalLy
acout_lettlly
inlet
tile
Clio order
frequency
in reducing
oxcita_ion.
ia of
nre_t 0£ 27_.
prc0aurc
be eoztcrolled
the
of
i_ to b_ avoided.
value
can
behaviour
perfornce
1£ hiBh
dfr©citon
a npccinlly
©xporimen_a
with
of
the back
o£
Tile
uitit
I
,in open
(ain_lin$)
,pcrforac©a
of heine
Ilolea
2Ogp while
can be critical
chanaca
for
8 tnvch_mi_m can
If the perforitted
pitch
C bad atabbed
of
retention
_atinitudv
a mit_imum level
producln
the flap between
cban_ed
ia Lhc hol_
Pvrfor_tGa
an open
aource
The ncou'Jtic
uignificantly
_trca t tha_
all.mater.
at
repreucnto
noi.c
by brldginB
pipe.
elnnl*bor lu not
_lvinil
thin
how chin
ill _[ren_tit
20X open
Thi0
unle_a
ed.
or reduced
with
metrua.
_el£-cxci_ttion
of
nppro_tch
to _aturation
(c)
_ compl©x
thn
_ollnd
forcing,
be effectiv©ly
by {:hemeaauremenc_
i
_uppr©,,cd
in
'
An exafuplawhich lllu_trate'Jthlu hOllO _eneratlon mechanism in
in©re detail
that
iu provided
ta found at
illu=trated
that
by the
acou'Jtic_lly
an expan'_ion.
in Pigur©
in predicted
11.
Th_ obucrvation_
The acoustic
by linear
tho tJp_trel_m duct
=yncroni_ed
acoustic
l_ M:own in Fitlure
wave with
with
ll(a).
_heddin_
ar_
and analytic
Dtandlng
analy01a
vorc_×
zero
flow
1]O dB cncitation
in
1111a wave can be deDcribcd
by
lho
vortic==
pa(_Pt)
,, l:aalnKlna
form of
tlm travelllna
in Fil_ura
jet
ot excited
but
ll(b)
flown
can bQ el©only
M
[11[.
It
lielde.
and then
plotted
prob_
devalol)ed
n:_eociat©d
with
th© ahed
from a number d_ ob=arvntlonl
l_ an aatimaL©
_v=-°k2x=i(WL
e
ratlmr
than
a pr©diction
" k2x _)
diatribution
Th_ mean =quara
,for comparison
microphon_
_iald
by
The cor_bincd pr©=eur=
acouatin
pot_ntlal
haa been
described
PV(xP=)
.
in _igure
i= the =urn of
If(c),
and
o_ th_ uum ham b©cn calculated
valuta
with
the potential
obeervatione
made with
a tr_vc'llin$
_h= n_re¢_¢nt i= within the _ccurac 7
o_ the meaenrc_nte.
Though
potential
which
thz
not
fl_ld
then
o_
chambtr_
Acoustic
may not
la tempting
charactcriatinu
be the r©ault
• t dl=continuiti_a.
/
/
in free
cnn int_r_c_
ntron$17.
Thig
gilt a_ct
Tha rol_
and tnllplpo,
euppraa= tim vortex
unallectrd,
It
r_diatore
th_ vortic©a
may radiat_
_apannion
cha_bor
©£ficl©nt
formation
to _|meularn
of
being
of
it
epec_,
with
amplified
n©arb 7 =urfaco=
to happen
by r=eonannn
bridgn
tim other
wh©th©r= pothapa=
found with til©ncar
=imilar
_cheni_raa
travellins
whuc nppearl
tim perforate
whila'lr._ving
th_
within
in the
i_ thue to
acoustic
propertiee
_an 7 Of the non-linear
¢lem©nta or silencer
tyetem
c|l_= include
vortex _h©ddlng
3,
HEASUIIEHE)_T AND I'REUICI'ION
Au ouglinud
i_
based
ell
opc:_
requlred
an
l)redictlon
(un,Jilcnccd)
in'Jertlon
uniL_
the
of
For #inipllcity
cterlt|tlc#
l_
then
au
.milfler
_ituat_d
whnn
the
eM*auuL
pip©
_nor_
di**tribut_d
uain_
maLricc_
Mmuhl
_iv¢: I_Veciuely
_1_in
rrm_in
tile
the
can
tho zelatlon
nu
if
ba_cd
in
flow
th© analy_in.
and
hn_
hecn
tCm*l)nratucc
£1ow
.hown
condltion_
th_
and ***elf
let
Predicted
eontainu
two
can be calculated
tho
nourco
no|u#
alre*.ly)
tin*at
here,
Inpu_
The
or
hy
end
tw_ inetho(l_
on Lhn #aln_ nanump_ion_
to each
_Icn*en_ In turn
ellnrlzct_ri_It_
runnin_condi_ion_.
d*m allowanc(* for chl# can b_ included
Frbm _hag
to
of
_;_|lll_t,q[_ frequency)
bctw_nn
will
appropriate
_nsino
for each _Icme.nt.
lon_
ehar_l-
occeptnble
an dc,cril)ed
o£ tll_ l)rcucrilmd _.nEin©
du_
tranufer
_yutcm
_yntcm ,,nl_
element.
ealculnLed
be
chnrncteri_tlc
nu Inns a_ tho inlmc
aria(:,
tly'JC_m with
be
apart.
nnd r_flectr.d wovea
#o
th_
Ih, certainti#a
each
nlao
lind
o_.t well
unite
valid
'file
the
nttcnuation
Thlu
l)ipe between
the aal,m reuultu)
Inw_ri_-nc ad: each
are
B _IL Lhc
the
pipe
predicted
Mior_
r_prauenClnB
condltionI%
1_
of
Chcn
ezh**uuC dlnehar_=.
im_l volu,u,_v_loci_y
procmh,rn
_tnrLin
#Fen
los#.
Lhu trnn_fnr
Lrazmfcr
boundary
and
relatively
Lhu incidnnL
|)re.hum
and
iu
i:lirli*:r)
ou_pu_
calculatint_
t|icn)
can
191) the
in:)ertJon
near
bed
included.
I_IIV(EIeli_DQlon_ .'l[ f_h_ l(]w_
wi_h
workln_
a Le_t
unit_
[hiu
cli0_aLctc_i_tlc_°
unity)
mu£fler
A_ la_In_Dlled
lo_u
Lhe run of e×hau_t
I)/O Or _o_c
ch_
and
pcrfonnnncc_
Fo_
chnrilcteri_tieu
e_ample
_1_ the
with
or
pipe
acoustic
on
ir_u[flur
lnz;ertlon
tran'Jfcr
for
t.ken
taken
it* _iCuatlonI¢ where
ll_ 41r.lellli_
two
'Jy_tClll
idenlly_flr_t
open
Cranl;fcr
(see
may be
#y_t_m
th_
The
Lhe
the
I)ERFO}Q[ANCE
prcdlctloll'a.
mca._Ul'emcncu
_iLh
involwrl
o£
included.
Lhe ratio
c_hmaut
o_
_ystem
lou_
cnlculnting
_ilencer
of
Inea_urulncnt_
a'_ inensurc'mcnLii
ch_irilc[:urJi_icll
Lailpipe,
from
evaluation
loss
[_Jl)_
l_ell
of
Lrant)f_r
ea_Iicr)
in:;c_tlon
pUrDO_C
OF FXIIAUS'£ S¥STEH ACOUSTIC
8e,neratJon
uithih
in th¢: model
it ia
clear
alwayn
Im
th_
for
thal_ _lle
included
3.1
Sourco
charncteri_tieu
The acoustic
from open pipe
uourc_
ch;_r_mcteri'Jt_c_
lauasuremunt_.
of
To illustrat_
the
entline
cnn be dealt*cud
how thi'_
ciL[I bc
CdUl'led
out w_ mu'Jtllrat _et out _ model of tl_a_y_tetawhich identiflc'_the
source
il_
will
eIclllI_nC.
Tile prlinllry
valveu
which
velocity,
_l,CCify
_ource_
To complete
the
lndLvidu_tl
are
provided
Cllll b_ ru|)re'Jel_t_d
the
effective
_ourcu
contribution
to
de'Jcriptlon
totwll
tiource
the.mqni_old.
A convenietzt
re[ere_ce
ill therefore
tile ,nnnifold
fluctuaCinli
hotel
inlet
I_aitl_
_trenl&th
volum_
wlocity
qtlzmntified
tiff
I_yat_m) r_preaenta
c,tit be t_pecificd
aa*_t
12
till acotttltic
_}tlcttititin
The driving
_eou_tie
pr_p_ur_
Ps can be e_tpr©a_d
p_ - U Z
_trentitll
Ior
voh_mo
£1ow provide_
._n
wllicll
in
combine
de£inition
o_ _ourc¢
or turbochar_Ior
nt th_
outlet
r_foretlce
plt_nc
O_lWitll an _ffectiv©
0ourco /mpedl_nc_
complex v_triableu.
Thu e_IIIIULIC
SJy_tClI_
load
volume
8
lmp_danct Za,
_lth chcou tlefinitiona
and ny_t_m apl_nrfl aa _howll in l:illur¢
Figure
piano
c_n bu _pecified
th_'ou_]h tho
one u,u_t a]_o
tile t_ourco
_LmC]lv_llw
itnped.lnce.
the
flo_
by it £1uctuatlnt:
of
characteristics
Th_ _ource
J]I
by the tlnutelidy
acou'J_icitlly
applied
velocity
to
th_ acoutit:ic
12.
_h_
_anlifold
_a tl
?. _
(OE
nource.
IIa with
mod_l o_ ©nllin_ and ¢_|laU_
at
th_
_ll_nge.
'l'ht_
ltn effactiv_
I_ot|al of
tho _omlrc_
_yt_tcm
or eurboch_rl_r
ouClnl;
flt_ng_
_
,,(_m-Uu)Zm
3.1
I>
m_aauc©m_ot_
umusllyAcoustic
exp_'_a_ed
a_ _ound obtained
l_r_anura
,
,.?'
with
l©v_n. m/crophon_
Thi_
or trnnnducer_
az'm
in£ornutcion
_a t_unlly
reported
root
D e°g,
colapartllJle
with
phase
3.2
nG tile
inforlnntlon
the
information
Open
pipe
ore
norlnnlly
reprt:_cnt_
th_
_pectrum
d_cn
zzoine
the
of
with
2.1/m
I/_th
vt_iocity
t_ifinaI
Pr
not
eqtl_tion
nignld
nt
dlrcctly
3,1p
uitlce
procenning.
11 .._c
tb©.aou_ct_
^
drtvtnli
plana,
croon
Pa
planQ
acct/on
_)
bn
can
th_
then
of
the
neceuuary
w
be
uncd
_th
ch_a taLlpLp_
(luctunctnl_
b_: c_leul_ated
voluble
_n
found
3.1
bug
nap/rated
^ICornnttval7,
th_a_
Illl
will
i(k-_''_)]
n i'_t
_ith
a di[£©rent
ncountin
cnti|nat_
o_
Pa"
tit
the
in
Za_
thin
var/abl©n
Um _nd
with
Ua and
?'m remain
In
land
can
bc
charactarian
,naff_cted
Z
a
for
(i.n.
Provid©d
information
which
a change
3.3
lira
uacd
c|l_
with
a ninltln
to
n,lurc_.
a turbocTlind_l:
cnl_Lna.
on_
by
+ R(1-M)_
two
th,t
alter
prca_t|r©
from
by chnn_ea
for
©xiat¢
charBed en&in*,
The
n a_e_nd
unaf_©ct©d
radiated
can
the
it_orllttltioll
o£
|ha
nol_Q
rcpr¢!lletlt_
ZD. can
opec|rum
_. ,
rtldl_te(|
reco_t|
pip_.
ob_arvtttit_n%
providna
equation
evidence
itnpednnce
l©nllch
area
- p:[(l,H)*'/k+_
R_penttnB
Zra nr_
of
tibia
rcuulta
pe._.
A In th_
o£
t_|llpipe
tilt:
tile
Provided
t_muj
level
The
of
2.14.
_amo
prensure
conditionn.
Thud
tlmplltude
pipo
t_otmd
field
cqu_ttLon
the
for
th_
opt:n
usua|ly
energy.
in
recorded
_t atr_Lght
p
t
by
tile
Sue||
_zty m in
b_tnd 'JpettruIn
_ot|_d
_ definition
wh©r_
uound
tire
_t_ tt n._rtohr
|ha
Un
naturally
Lhe pre00ure.
preu_ure
in
Ire©
rtld_lted
to cvnlu_tL©
^÷
w_v© po o
incident
o[
Pu de[ined
di'_cllrded
lueiitlurelllentu
hllvf_ been
_qunt[on
Some
pressure
been
pretz_nted
tol_t:ther
nolw
value
lin r.ITI.U,
made undt:re££ectiveiy
tltld
and
i_
hound
haa
Opczz pipe
©hanna
_¢pltlre
lJ,ea,;urt:lnentn
recordins_
_|tJw
me|in
P fJ _vlllch
can
a _Ll©nc_d
pratlic_
th_
_yac_ta
22
_rom
inner|ion
th_
open
lo_a
or
predict
pipe
m_aurementn.
th_
4
....... ""_'::.a_;_a,.:.a,¢'¢_:;',',.S_,..2,,:.;_,.,,_
,. :,:,.
..........
•.......
..... ,.. :-,:,_.,,_,..:.-.!_''.'_;r.!S_4
;;
_
t
]
COl_lp_[
I
t>otweell
_iOn_
Ono
_aZllnple
an e_hau_t
opctl
of
of
heavy
in
metrca
7.5
of
for
th_
line
15.
bur
per_or_trtd
the
performanc_
plotted
in
the
noitt
nyatemn
predicted
only
in
the
_'
ca_t
b_
performanc_
utud_eu
/or
of
o_
the
_lm
eahauat
e_hauat
levelu
condition
With
in thin
wure omitted
limit.
and analyacd
r_port.
l_ =hown by tim
full
arc _UO furthur
[lgtlra
al_o
70 dll^ at
pcrfoz'med
tlct_
Thc two uilenced
e_hnuut.
ia
The dc'Jlsn
bclo_
deocr/bed
dii_
which
aytcm.
a hack prea_utc
_rc
tlp©ctrum
a uilenctd
wars 105 dBA zLt
enfilntl
pipe
tk_rche, d in Flfiurfl
in Oll_ of
them.
tile de_ll_n _ n©glec_lo8
thA two nilenoud
nupprcnnivn
floe
by
the reeulta
bY linaar
with
_t
the
_yst©m with
15,
Tb0 acoustic
nol_¢%
_is g aignifioant
1600 lit.
demonocra_
nola_.
i_ aluo
/Icoutrtc
thfl value,
They nitro conf|rta
if
7,
Th_ purformatlct
theory
ia
tim
uam_ if
txpnnaion_
ia
i_nor©d.
pcr£ormtlnc_s
rc_l_nuration
diacr_pancy
Tim rm_=oa
brldgan
tinc_
©ffocL_
|m|:weetl
pr_dJ_tad
hun not
o_
that
tim bridg©a
FIBurn
th_ purforat_
tile pr_d/¢t©d
non-linflar
around
in
acoustic
ulmddJng
o_ t|;_
a_ntema
flow
05 dBA can h_ e,xpacte.d
of around
_ou_d
havre thl
There
for
for
b7 vort_
nliretmllt
pr©_int
for
implied
©xci't_tion
on _l te_L
_t_ur_.
levnla
a_
tus'bochar/led
an open
w/thin
with
brid_©a
brid_en
omitted
frofa
c_;aml,|e
fuz'nlcd part
by the Deparuut.'nt
1/3 octav_
_lm aamq dtallin
Th_ r_aulta
ptr_orata
noi=o
. Included
pr©dic_©d
Lheory
z,n enlline
rc_ult_
a;ld d_iiln
methods already
pipe
of
A further
wlt|l
The'Je
required
or load
me_anrome.nL_
;*_r© of
13.
0p_n p/Ira mcaaurcm_nta
,tcouatic
_yat©m:
flow
upecd
open
in Fillu_©
of tpcctr_l
lfi,
thin
wi_h
th© _yutera
linear
Th© r_=ulti;_li
acou'JtiC
in Figure
'Jponuorad
notre© of
any
linear
perfortt_ncc
Kinl_dom.
United
65 _aa o_ mt:rcucy.
uaing
15 and
full load
for
ra_tr©n
wlth
pet'fol'matlCe
IImzl_u_ed
ba'_ed on t;l_n,Jure:ncnta
project
the
under
apccifieation
t}lc
(Ix]lzttJ_t _y_Lelll bcllC]l _e_t
'l'be unuil_nced
7.5
prudic_ed
in Fifiur_
v_hicl=
envirbnmenc
I;_[elll
bcLt_u(!ll
Wa_ pre'Jented
¢oznpar_son
Lilt'. _yutctl;itLic
ine,l,_ul-ed
Zl colnpar_uon
meaaurolIletlt_
i_ pre_ented
quiet
lind
,Jy,Jtcm zmd that
p_p_
n _i:rl_l_r
bed
predicted
at©
o£ both
tho flotz
noise
II_wcvtr
can good
only
with
tll_
broil aupFrcna_d.
anti menuured
bo_n ea_abli_h_d
but
thl_ is Jute abnv_ th_ fraqutncy
when ihe _iro_ of tile hil|litr
order
taiiplpt
re_on_nc¢
mllii|t |_ reapontibl%
whll_ it:i_ worth notin_
tha_
_ropagating
models will bncomls cut on.
_,
: L,-,t :-L@
,,_
i_¸¸ -
,.:.
;,
_
,,
_.
%,
•
,
The Itluauured
recorded
with
in'aertlon
In Fiflura
no attempt
i,ea_urcmeat'_
16.
to
to
account
allow
The crou'J-hatchin_
produee_
_inct_
had already
cotltlLitllt
whila
o[
tilts
th_
(ir_lt
chmab_r
linear
thoua
plallt_
theory
will
only
o[ hightlr
order
200 II_,
tluighbourhood
relllforcea
order
higher
Calculzttion_
to about
wttil tile
at
.*;how
1200 IIzill
flow
that
I)t_ reliable
propagata
zl_ a
ill the
in the
propogzttion
will
can
lomla
Thl_; result
obuorvatlonn indicat_
acou_tic'eneray
utlderatanding
dip_
dlacr_pancy.
ll_ in tile pipa
thi_
lozld and speed.
bzmda.
inod_ corrc_ponda
Theua
wltvc
at which
A proper
the
*llld 3000
thitt
Atcou_tie
35 to 60 dB above
two protIout_ced
for
temperature).
zlcouutically
of
li.% 1]3 octave
pipe
(e.g.
difference
be]laved
i_
iu raw d_ta
open
each inechnnical
ttcou_tlccnerBy
iti thnga COmlmn¢:nta.
of
at
circumfcrcntlal
thu tl_panaioll
to the
wao in eaceu_
indlcnte
inrldctt 111islzt
ba rcuponuible
tlm_
with
engine
_ourcc
loau
1250 Ih: and tlm 6000
that
brldge_
here
the range of variation
th,tt
inucrtion
with
plotted
in flow condition'J
nlcauurelnenL_
vohllnt_ velocity
0ttggeotion
the systez_
inodlficatlon'J
ch;mge_
in<licatea
careful
tb_ IZleltaurcltletlttl
tile
Ilia
for
for
indicztted
TIle predicted
Io,a'a for
The information
conditiona
tile prcdictiona
trcquuncl©a
llZ th= hiiiher
r_0do propagation
below
ordzr
mod©a.
flow
preaent
with
li_a to tll_t
[utnrtt,
3.6
Saint
olll_rvation_l
conc¢._cni]_
Tlt_ me.aaurem©flt_
t
i_ a w_ll
aatabli_lmd
Interpretation
o£
eonditiona
within
obtain
tha duct
and rnflect©d
a trnwtaing
cara
o_ the
alga
I
t_clmiqu_
rantlltt
tll_ _Rprrimenta.
ia
n_or*a a_vur¢
©aiat
approach
radiated
£rom th_
*aid Ollotzld pr©a©nt
tilt
al_o
problmna app_ara
in gila lnt_rpretaeion
ainc_
_tanding
_avu ._caaur©menta
Thin
oba©rva_iona
i¢ a lnborioua
at=
in r©f_rr.nca
o_
th_ r_:aulta
la
procedure
to I)_ obtained.
I.
fre_
£i©ld
0£ prnaaura
©ap©rimer, Lal ptobl_rat,
producinr
outlet
Tilt
provided
Tha m=a_ur_ment
tog_tbur
exbatttt
ft:w problcma.
_traJghL£orward
_o atandin6
mlcrophona.
r=llabla
experimental
required
energy
got
po¢_a
prob_
it
meatlurer0_nta
tht_ _ound
wav= ayat©ma
A traditional
great
of
pr_ali|tr_
both
to cr_ploy
and rcquir_a
^ _l_ll
account
Special c_r_
0£ preanur_
inc|d©nc
wavan.
In
trawra©a
agile
th_r_,
¢e_ for exampl_ Vignr_ II.
f:r,cept for ap_cinl
r©_carch
near eapanaionn,
dun ;to tim non-acouatic
pot¢:ntial
£ielda
that can
aituationa
thin dana not app©ar a ua_iuf_ctory
or prae._ical
techniqu_
for
normal production
te_t: bed mt2a!;url21n_ll_fiL'Or
An all:ernative
ia
to employ wall
,nay involve
practLcal
obtained.
There i= rio _crioua
or di0turhed
in/=flier]
problem=
tl0w in
cllc pipe.
cxl=tcnca
gauSoa,
_=pttrtttion
in the
if
IIoweverj
el|at
if
uhould
for
{ran=form
t©clmqiu==
which pre=_ur©
tile
are
chat
obtain0
informlltion
no _tanding
with
wave=
_o_e
tran_-
syutem utronI{,
ar,_ obtained
record_
be _i_ed
meaaurcmcnta
can b_ employed
the=n
Tlleproblems created by their
on the
in Icu= =hail _hc wlw_lengch
frequency
oi
theru
wJ.th any pt'act_cal
slmultancou=
These
evtilui£tJ.oII.
mea_uretnento, but
ewtluation
problem
u/ll alway= llepro_ent.
can b= overcome#
two pressure
pressure
a condition
loo_ Ine0flurelucn_o,
=tandlng waw¢
COmpOla_taE
wall
with
with
a
_ound ac t|lt_ higl_e=t
of
are
rcqulred.
P_uc Fourier
tha amplicuda_
to extract
tha
of
po=itiv_ _nd n_g=t/w tr_vcll/n_ compon©nt_ or"{:h=_t_mdlna wave nystcm
chc=Q two =J6nal=.
from
Chn wave= _r_
Thi_
which introduce
_trong
^ third
dounsCreara
it
to make :_imultancou=
and particle
velocity
at tllo
pr=a=ur_
and parclcl©
v_loctty
measurement=
for
dir©c_
in _trix
application
me_rem©ntn
t©chniqoea
ma_ oitar
in
mea=ur=m=n_n
and velocity
r,mthod_
dl=coatfnulctco
ob_.rvation_
arc
o£ wall
Slmultaneoun
particolttrly
uuitablt
o_ =y=tcm performs=c,
a hot 8a= flow
ar_
di_lcul_
made sith
evaluation.
buc th_ ne.w optical
Intak_
115J u_lng
b_cn undnrtak©n
|n_a_uremcnt_
acou=cic#
wholly
=amt_ duct:paul=ion,
practical po_.ihiliti_a.
have alr=+tdy
_valuatfon=
arc
or oth_r
I:ha_
th_ flow.
in
pr=s=urn
ValoclCy
_yatcm
wall
imrlormanc=
preas_re
hog wise=.
In thi_
c_8_
though the ttmpQrnct_rtch|mgc= arc rclat:lv_lyr0od©nl:,
_hty w©ro
large
©noush
co introduce
diliLcul_J=a
and ulgnnl interpret=tie=..
Though
=hould b_t,_rctt
o_ lluchdi_flctllti_=,
4,
=i/in=l=
of bend.
di_tarbance,
pol_lbl_ity
or= _h(: a=sumptlon
relic=
the pr_n=ur_
plan© and that
=0 may noc be appropriate
procedur=
w/Lh
the hot: wire
igtlch i;lor_ ,_xpcnsiva_
calibration
optical
t=chnlq.¢_t
DISCU,_SION
P.
The tnttl)'=i=
lyatem
I
©lem_ntt
lmprovins
and rcsulC=
_nd how tlmy
=he. und_rltand_nE
pr=a©nted
hera
ltztcract.
of
rh_ 26
acoustic
r©presunt
I_ ha= been
b©haviour
one approach
to .
uhoN1tthat concept_
of
©:<haunt and inl_
!
,.
dctnil
preacnCo
tlm Jtnalysls in tvrms
i8f0191,Ilol,lnt,ll21,1lsI ).
and
of Incldcnt
reflected
l)t'csutlr_
^. ,,lt_r,_o_i,o
i_ to p_,'.,ont
_ho
_l[IItlyg_Ill t_rfllsOf tr¢il1_t/crIilaLricca rc1_itln_ LO Inpt_t ti[id
otttptlt
pilrLiclo velocltlc_
_Ind pressures
for czlc|lclclncnC (c.|]. rc[erellceu
]31. 14l,).
_t i. r_os,,l_d t|,,,t ot|,_r,_t|_o,lao_,,n,|y.i. (_._. li41),
Ilztv¢
developed
/tluo
been
for noisy
/initu
control
clement
w]l_clt
analysL=.
methods)
proved
inndcquatc,
lo
Thcsu
_or which
A vnlid
that
thay
_hould
pr#mticlll situ#ttlons nnd mua_
new
llncnr
criterion
b_
uuefnl
+lltern+ltlv_
tony bc particulltrly
for provldins
|Jcll#tviotlr
o1_ components
bQ judged
c*IN provide
r_Icwmt
(c.8.
Into tllcacoustic
_lcotlatic llnillytllg
II*L_no for
by
£1cxiblc
providu
insight
llpl)rO+lChe_
which
_nd
coch
relullly
reliable
of
tll_ mcthoda
applic_lblo
Inay
to
pr#:dlctlonl of i,couatlc
p=rforr_ancc,
Finnlly,
cngi|l_
Som_
lntak©
and
results
hav_
c_amplc¢
of
the
vxi_
, ,
,
_xhaust
boca
problem
ny_Ccms
ill t|lc noluQ
li©_ in
r_l)Orcctl hera#
but
wh,ara the "_onr_e chnr,|ctcriatics
_cou_lc
uh_ar_
m_ntment
noin=:
an outstnndlng
load.
_hla
in
Th_ra
no_
and aourc= analy_i_
control
p_'e:diction==
i_
th© cne_.
in
clever
auch
charactcriuin_
hltva bc_n r©strictcd
nppcar
to b© Ind©pendcnt
evidence
ar¢
that
uf
tile _ourc_,
th_nR
So that _cw
tcchnlque_
control annlyai_
msoy other
dcvslopm©nta
to
vx_mplcn
In mun_ttrc-
rcqt_Ired to pr0vidc
rcl/ahl_
situations.
F
I
240
I
760
I
780
l
800
I
820
__1
840
i
860
Frerlu,._ncY 1t7..
FIG.
F,
ln.
ACOUS11C ENERGY TRANSPORT AT A CCJHTI_CTION
WITH SIDEBRANCI_I.
,..
I
8B0
,5O
30
m7
EI_.
....
O
fo
h_a_ur_m_nt
IQ
,
I
J
.I
/_ch
FIG.
i
I
i
.2
m_b'Ir
In 3
l(b)ACOUSTIC £N_RGY TP_NSPC_T A'TA CQNTP_CIION
WITH SI0_P,P_NCH.
I
20.0 Lo910
i
_'S-P.L._cz_._J
ZC
I
I
60
x
M
M_
0
g
!;:.,!:.,J,;/
_
I0
Moolurernent
I
.I
Mqch number in [1]
FIG,
2(n).
I
.2
ACOUSTIC ENERGY TRANSPORTAT AN EXPANSION WlTll SIDE BRANCII
I
I
3
j,
"L_.O
.,.....
,,
,,
._...._--"
, ,
.0
\,,
\
/
\
t
fo __
2.5
, _._._lt
201
----
_
2.0 - o_/,h
0
J
.1
I
.5
.
Ficql_ncy
FIG.
3.
,L. ....
.2
porflifliiliir
kil
_ .
.,_
END CORRECTION FOR EXPANSION OR COiNIIIACIIOH.
r
m
I
:
,0
I
!
1 1111
! -f
1
_1
p
2o2
k
D3
117 3.9
Meulufcd
•
6.o 4.9
_
II.7 4.9
×
Calculolad
J
.......
1
J
-"_ _. I,
,c
_(
_
_
._
"
I I/[_/_
_
o
I
D4 _5"1
_j,
l
200
100
D5 " 2"5
.__J.
300
FfoqU_ncy t_,r
FIG,
,_
. L ,
4.
PERFOR_NCE
J
O 2 _ 2.B5
_e
o
fO
3
OF FOLDED CHAMf',_RS.
I
500
I
600
i
700
[
_00
i
i
1000
FIG.
• t/
i;"I,
,,
5. SPECTRALCONrENI
OF FLOW NOISE
\
\
'70
"" _
*
\
X\
\
_'
-
°
I
vb
x
A
400h/_
300h/_c
•
o
290h/_,c
200h/,_c
i
2
fiG.
d
r
ii: :i/:
I_,
0
I
4
6.
I
6
I
B
I
I0
.
FLOW NOISE GEHI_P.ATIONIN AXIAL Ci",AM_R$.
i
12
I
_T
_
"_
_
_I"
,._,
• v/
_"
w.._,,.
:-#I.,
"e 285 ft/_ec
inline
*_'
@
_'O0
fIl_ec'
c
_i
205hllo¢
d
0
200 t'lllec _"
d
6O
,_L w,._,,=.
'_
_A_
V'I
5O
C
0
I
FIG,
q
I
i ,_ , _,
7,
2
Separation
_/d
0
3
FLOW NOISE ffEDUCT;Ohl BY PERFORATES,
A
5
El
1.0--
Side
entry
.[]i
j;
j-
_- ,, .4-
f
"6 '_
,/_/"
.,_
ID '_"
I
2
I __
4
S_pe lotion
FIG.
8,
n_ pc rlolale
I
I
1
6
1]
10
x/d
t',ACKPRESSURE
OF EXPANSION CI-IAMBERS.
12
150
/
023 Hz
141
. ._C
_
-_
_
0__
°1...__._,..<
l,
_.;,
/,="
/
z /
X
_
110
i
I|0
.
.
I
.I
120
FIG.
,A,
•
9.
FLOW ACOUSTIC
,i
130
S.P.L. nln_
t
_."
._
140
,
-
671 llz
BOOtlz
l
I_0
I dO
COUPLING
AT AN
,
AREA EXPANSION,
M_0.|I
F-" ' i
I.....
_ I.. .M
1
(3
/,
1,10
/o
/o
130
,/
/"
Axe/'t
j/_'
/
7^'/'
./
,_,
120
I_t'
/.rd
I_
/_/'P'_,r
/4"
f'
i"
El
A
.. A" _/*
623 ,Iz
DO0 I-Iz
J----__
I
I
110
l
120
5.P.L,
FIG.
3
M_O.|I
_/d = 2.5
,,,0"
1O0100
I
....
too,,"
t
130
I
.
t
140
,
I
150
l
160
dB
lO. SUPPRESSION
OF FLOW-ACOUSTIC
COUPLING fly A BRIDGEPERFORAIE.
e
i':;:, _: :._
__
,_
,j
r:°
M
j
.._ I001
20a
lOa
P_
_a sin k 1 xo _wt
_____--___-_.._ooo
_ ooo
o:.o,o
(a)
lO00_'Pv
"_
kl :_ "ff/lOa
/_
_
_
Vortex travelling wave
"
_xk2_©i(k2x I O) olwl
(b)
120 -
,_
•
0
Q
o
•
0
O
D
"0
,
11
_.
_l'c"
FIG,
"
II
_
i
SOUND pRESSURE
LI_VELAFTERA DUCT EXPANSION M = (1.I ; (2a _ 25ram; Uc - 0,63 MCo
I
lOa
20a
1250Hz
;
i
u1
i
i
4J
r_
120
meosured
pipe
tO0
--I
s
28.6nlm clio.
._J__
.....
predicted
._,
| .83m
60
open pipe
I
20
I
_
1(10
I
{
I
1000
76ram din.
Irequ(m cy Hz
.TZ,
28.6mm dla.
'_, l .83m
FIG.
I
r
t_
13
SINGLE EX['ANSION CllAMBER PERFORMANCE CONSTANI
VELOCITY SOURCE LINEAR ACOUSTIC ANALYSIS
VOLUME
J
,r t
' I"
e_panllon
|
_r,
open
305ram
chamber
-
52mm
100
_ok ope.p_r_
"222 I
O0
,.,
/
Syslem wilh
perforate br dqes
?
'_'_'__
\
I
60
/..,,
/ _',,
k------_
/x
,_
"_"
x_ ,V\ /\x
'_*" _/
\
/
"_---/
_'_'_.
15
,
/_x.._
./
I
_Jlcnced, p_ak m_olur©d
_
"_, peak predicted
6300
AVERAGED MEASURED PERFOR/v_',NCE.
FULL LOAD 8 SPEEDS 100G < N <: 2350
I
I
i
II1
. , ....
/ --
400
1600
third octave, filter band (H;:)
1O0
brldoc_
.;"'-,_.._".
.
\ _,._
FIG.
'
"\
_omilllnu i'_rlorale
(flow noi_a)
I
TURBOCHARGED DIESEL AT 7.5m
I,_¸
II,
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I Illi,I
J,
Y.
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lh¢ i_ol_e, and
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for d_ff_r©n_; _n_lnut_,
A dleetcf i?11_11_¢:Ol_Jl'lll.l?[I tlllthrl3ti, fed COflcin_lotLIily _i1¢1_ hel%Clt I_h_ blIck
pre_llUrU _ll. p_rl_ load h_l_ a _l'l_atur _ffulL
on Cll_fl_l_ i_crforlnllncl_ _h_ll In ,q
_pltrk ll_nlCh_n _nsfne which ltJ thr_)trlld
_tt; parl: ]_nt|,
A Df_¢ol-©ni_Jne
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In 8_'nernl I_u del_l_n_?d to h_lvQ _t I_n_flur
balk prel_l_Ure,
Th_ eft_ect IJf ¢?tl_ln_ u_er_tl_lnl_ cul_dll;lonu
on ^°w_ll_hCed ©xh_tJ_Jt noL_lo f_
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3,
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utll_lll_' t.llr_lLl_lll_JtJCILll ¢{Inll_|¢tu
lignitise of uperlll;|on,
fi|l:huu_h _xhnt_ut noftlu la kr_o'#l'J_o Lncr_nll
In ll_,v£1
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by thu clxht_ml_ I1_ rnana
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all_U I_r_mlre
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op©nlns°
|_ la
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once t#H_ _?lll_zle Ill _h_tllSIIcd I:hune pllr_lm_celrtl _t'_ [|_
I.hLItl th_ lxh_ulll:
Itoin_ |oval
l_ t_l_ by _h_ _xh_ttllL _lU r0aml _'J.o'_ r_e,
TAIl, PIPY.
of tile enl_fno _?dt_mrl[ ayz_Lem ulncu 11 fa al: I:ho call plp,_ _h_l: n major
l_orichm of the _eou_LLc
cn_r_y of ¢11_ u_hauac
prQanurc: puluctl
la rnct_al_©d
_,_ ¢_oum[. 'fllerc t4ml con_ld_rnb,l,c
cni_fu_lon
concuT_J,I%R £])_ d@[:Al,_l O_ I_,_ll
rndlntinn
[=rc_cuun Illlt_f
19/ti_, whcn l.uvlnc and Scllwin?4ur Ill*
dlv¢lop_d"¢|IQ
theory
of I.hc reflected
_aw? from nn unflan_.ed
circular
pll m _Jthou_
flow.
*_;J.llCt![hell_ :llvernl
expor/lnulltnl'
_u{llc_
Imv¢ bo_3 performed
co d¢¢¢_'_lnQ
the _ffcet
of flow on I:hn rufb=ction
praceua
[2,3].
In thl_ rnor© r_ccnt
work chu nmnc t+ll_nLfllnn_
r©nul¢ Jn probably
lhaL obl:aXn©d by ^lfrcdn_n
and
Davl_
12l who, by n:lllumlnll monopolu radiation
frnra I:he pipe
(f,n.
©q_nl;ln_
thu ¢_l_erily of tl_u pla_le wave 111 _lle pfl m Lo thu unursy
In the apli©rlcal
aprlnd/ng
w_tve oul:uld_
Lhu pipe),
developed
Cha falXo_lnS
c©lntlon
h©l:weel'_
¢he nr_l_llC_dua hi' chc prcnauce
p
_1 th© plan_
waw Jnnldo
the pkp_ ¢o gho
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wave
a llu_h¢,r?i
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Po Ou[/lJ(tt!
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from tll_:
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trill
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A TIIAHSFER-FIIHCTIOI_
^COIJ_ITIC CII^IIAC'I'I_R[_TIC5
cnut_cd
by
refrt_cLlon
c_f
'['l_CIIriI!_!l_l- FOR HI:A!;IJP.][HC _111'."
[)F EXIIAU_;'I' SY:_'I'I!tI_ 1_2.111 I_LO_
11(_rP_i| [IlC|_I_IICI_
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fly=tern.
Oi_c©
the
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e hl_wcv_r_
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Cla_icnl
m_l.hod o[ d_compot_ln
K _tlmdln_
wrlvo _lytll:_:mn In divot0
1. th_
• tnndlnl;-wnvu-.ratlo
(,'i_l_) meLIiod
[4]
hi which
n .m(111 r_Icropll_)nc
or
mlcl_ophon_
prol)n
1_ mnved n_l_llly
il_Ul_
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to mcn_iuru
ch_ _lmpllLtlllt_
and ]ocnl:lon oL" l:h¢ nco_ml:_c l_r_:_xlurcrnn,slmn nn([ mlnlmil.
From thin In_ormn_Ion_
_h© rnfl©ctlon
Com[[_.eiellt
clln _ic d_ttorrnlned.
Tile _;_
mctll_d
hn,
anw_rnl
d_n_dvnn¢_Ru_:
_.
The. mu_hot|
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h.
The
l'ctcl_lll'cll
ncoi_h_
ilfl(_
h_PI_CC_ [II
mlcroph_)n_
position
l:h, fle oI" [llC_ reflcct*:d
I
t._ciLn_lon
o_
_Jl_tU _OlIUIIfR][III.
mll,ll:
wltvu.
hv
knt)wlz
'['lllt_
(l_Jl:e
C/IIIHI_ll
_he dtl(:t
nyllt_:m fl_ dlnr_et_
accur_lL_ly
dlfflc_iX[y
I:c+ rem)Jv_
IlL
¢:,
_'IIQ mlcrophon_
_un_ h_ m_ved _lL Jl_nfl_ ii h_[-w/iv(_(_ll_Lh
fr_qu_.ncy
e_ Lhnt
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uy,tcm
hne t_ he qllJ[(_
]rl ol'do_c tit
In_lk,'_ l_CtI/lul'llrncllt_l
Jit Jl_wt!r [f_qilenc[_'l.
d.
He_N_r_'tlt_l
nffcc_nc|
l:hnt
by
hnwz
(|i_llilpntLon
to
nt
I)¢_ mmh: within
th_
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w_ill_,
n h)nl_
(Jllet
h|l_h
lit t,llctl
cumh_rnom_
n(!ctiol;
tht +
frvquvncle_.
_tfn
I
e.
Hhen there
_tcrl_phulle
le flow in the duct|
:Jyltt_m clJn colnplett_ly
the flou
nolu© Iten_'r_lted
muuk the .couatlc
_lav_
by th©
b_ll_
IItt_llU Ur t_(I *
'l'ht!rJ_ dl_ldvitlltafie_
vlt'l_.nlly
elimin,qt.o
the _Wi_r0cthud
f_r th_ roll,tilt© tu_ttnfi of t.,:_hnuut i*yutem:J wlLh flow.
ttu n protticlll
taol
Other
le_lJ-ct_nll,©ruol_e method© of tJt_por_ltln_
lncld,Jnt:
_l_d reflected
w_'cet;
h_tve burn tri_d
to Liv0id :Jonl_ of th_ dlf[lcultle.
JtJu_. cltud.
A dirtier
._p_lclt_l_n
of In©Idyll|
i_nd _'cfiectcd
r_ot_tl(l e*_n b_ _tchleved
_lch
the tJ.Ju _f
I)ro_ll_lll_tl uhort.-ducntlon
e_clt,_tlu,
pul_u
Inn
roll, lively
lon_ _ec_:lun
td
duct
15,6].
ilec_u._
of thcJ l_,_th
of dt_ct l_ded,
dll_lp_tLon
ptabl_l,_
occult at ch_ w_lln
an mentlo_d
In (d.) .hove.
hie© I;h_r_ L_:dtffLct_|Ly
lit crclttill_
_ti/_clun_
|li_|l-lrcqu_l_¢y
COllt_rlL in tht-" _llo_c-durntlo:t
ptlll_tm
tu ovt_rcom_ flt_w _nd/or bncki_roLil_d iloiuu Lit the uppur _requcz_c7 rnn_e.
Ano_hc_r mt_tllod of _Jp_tI_tl_ll_x lneldelll_
_ttld r_flecLt_d
t_oultd ut_:* cort'_lntlon
L_chntc]L_e. wlth n dJ_l_r_:t_ frcq_el_y
e_titntJon
[7].
Two w_ll-r_Jnted
r_lcrophol_tt
mt_nlJt_t-©I:[IQ n_ndln_-wiIve
_r_pllt:udc lind pht_
rul_ttlv_
Lu _t
t2umman rl_fut'el_c¢_ Y(_l£nJ_o _nd the crorau--'uot-rc_ltttlt_rt bct.wt_u;t the:t© Int_zl_urt:-¸
n_eiittt ltt |Jilted to dcct)mpon¢_ _|1o Itl:n[Idliit_ Wftv_ Into l[icid_nt
itnt| r_fl_JcLed
wnvt_Uo A_hotlll|l
tile wA_l-mot_[tt_d rnLcrQphon_t
reduce' flow rtol_
tht_ mc_thod
lu _:_t_ntLllll7
_n I:lmu cot3rtumln_ aa I_ht: _]./R _Lhod
A hrot_db_tnd rout|led In to bt: preferred,
ther_l'orc_,
for pcltctJ.c_l
ce_cl[_tt
ulncu_
111 fi¢iiarttl_
dlncr_ft_
frequency
mathod_ _pp_tr
t_ b© too tl_m
¢otlltuml[l_,
Art t,l© |1_'¢o :*_c:t_p rdlot't: ptlltl_n do no_ _ucm L_ wot'k t_o t_ell _(Jf
|)t'_ltdbal]d
©_ltnl_$.t_'t
In n duct:°
Tlllrt len'cc_D t-_tlldont-nola© ©x_ttlt_l(Jl|,
H_t3d(_m-llt_lll© _lxcl_A_:i0n r_c_t|lod_ _t'_ new wide.l)' ..t'.t_ In conjunction
with
_'_llt'i¢_r _n_llyttiLt eqtll]_rn¢llID p_lrtlculttcly
In vlbraLion
_nalynla,
mid It wetlld
ohvloualy
Im beneficial
If nuch powerftd
procedttre.a
co|lid he applied
to
c:_tlllllu_
lie|me:
J_entlll,_*
DtJr_ll
8 the
pnut two y©_rn, n practical
tt/llltt_rJ_unctJ.on t_clin_que
o| thin kind I.lu,
in fit©t, horn dnvelop©d
at the G_I lt_t_trch
Lnhor_ttorlva
for _ceufl_J.c I_.*/t_tl_¢_t_nl_ let duc_
nyc*tcmn with flow,
lt_ wottld
J.lk© Lfl pI'eOt!llt |1,_1_c ,1 derivation
of thf: I_©_[tad toP.t:_|lt:r with tc,t
ti_ltl_
r_l/tLiq_
_o liege k_l_w_ no-_]o_
tll¢of¢_lc_l
tloiu_iofln,
l_
tdlould
|1(] 11otcd
t)ll;_ thl_
J_ not tit© o_1)* rawle_-no/mQ
t'cthnlqu©
¢.hnt: ImJ hcen propo_ed
/t)r
¢_;_llounl:-noi_tl
tentlnfi.
|;©ybert
ii.d I_ona rt_cen_ly
prop©ned
ntlch _t _(_t|lod [tl].
Ilowev_r
I;|lolt procedure involve0
_ _athe_tJ.cal
[orf_ultH:_flrt t |)/t#t;d oil
ttt4to- _lnd crof_tl-_pec[:t_l,
rnl:hor ¢|l_tl*t tranuf(_= flJfiel:|ontl,
¢llttt ellflllot ¢_;inily
b_ u'Jcd ill pk*lictlcRi
teal:tn K. rf[I© I_fal]l_ff:x'-fUllCtio_
i_c_thod t|lRt 'dt_ dt:ncrihn
|l_t't_ CleF| |)fovldu
_
Jli_t_nl:itneotltt
rt_ltdotl_ t3[" qtinnl:l_/.¢u
utlcli an reflec_lun
c(_',zfJ[lciel_tS4 _nd tran_l_X_n
1o..©_ ov©r it t't_._t_ol_td)].ybro_t| [ruqu_ncy
gi]ll_{tl
trait3 Htt two-ch_m_©l
lnb_rnCt]ry nna,[y;_ut',
_{¢_|'l_rlVlll
K
tO
¢[1_
_lellP, l_Itic
dlllst_r_
t_|lo_/[I
ill
|"iRtl_¢l
_
t(_n_ld¢]:
|He
.rbltrar7
mict'op|ioflu
i[}CtII:_QI]Ii
_ Illld
2 A[, |lie
dttct
wzill
H_[,h
#t _l_pllrltL_Ult
all.Lance
n, In a .nlfo_r_ ducc of fln_.l_o lenKLh ulth
flo_
[¢o_ left: L© rlXIIt
tic; llldiCaLt!d.
T[Iq _'O_a_l¢
IlrUaMtlt'¢:l f_¢_gtlr_d by ¢1i¢? _iegttp|lffn_ll
f_L L[1¢_cl
l_©ationn
tony h_ _xprea_©d _t¢ the .tir_¢io_
of clsht.nd le_-i'unnlnK
cu_po_rtta
nl
_O_IOW_I
P1 " Pl r + P|_.
(2)
P2 - P2r + p21t ,
(3)
n.d
wht'rL_
l'll_ll[-
[,lit,
,lIb[
uff|e|elltl_
HUhlLL't'ItltXl
[
ilncJ
lL*fL-rLillnlllll
II 1
_lllll
llhJlt_llll'
2
4'llnlllulICIllfl
14
2 lLt the
[IJ
lhL _
h_l'lltlOllll
[.hC
IIl'_ll_tLIrt%
II_P h,¢.lt/mL_L
lifo
I
NII(J
_- 111111 ]_
The
refleCtjotl
deflnofl
denute
the
co-
;ltl,
I( 1 • F {plE}/l:(Plr)
(61
r2 - r'(x,.,
}IHp_} ,
(5)
IIIliJ
wllur_ Y dellotu.
wltll th_ rJBht:-
Lhu F.uricr
£r;lllnrOr/Iz,
AltJo I:he tCalZtl/er ftlnct|onn
nnd ]e['r.-runnJll_
prcrl.orell
nmy bo ulg_ren_e_l aa_
IlL2
l_
- t.'ll) 2 )IF{Pl
r
P
anttoci/ltcd
)
(6)
AIII_
•
II121,
while
I:h,."
I:l['flllfi[#_l_
/llYiC[.JOll
?
I {p2jt}/_ [plR,}
I"OI" (.hi _
totli]
,
[)['l_p_llll'l_tt
(71
lnfl_
110 WX'_tt(!ll
/ill
1112 - 1:[I)2}/I,'{pl)
F_OI_ oqulltlolm
_ i:o I_, iE
(11)
lrl _ecn thzll:,
1112 - 1112 (I.tR2)/(Z.Hl
I)
(9)
r
wlille
equnthm,
l, Co 7 .flow
that,
R2 - (H12_./ll12r)
:;ub.tikutint_
,zqu.tJon
lO Into
II1 -
I
'
.
!
L :
equatJon
I11
(111)
'J and .olvhl_
(1112 - 1112r)/(ll]2_.
55
- 1112)
for
Ill,
1¢ Folluwz_ tll.t,
(IX)
I:quiltlIJItm
2 ¢0
11
._r_
valid
_'[tller
for
dL.t_rminlutLc
or
rz_fldnlll
ull_r_=ll,I
iiruvJdt.d
Ftlur|(:r
tr/zl_tlform_
L'lt|lJt _ |ll th_
c-zinc. (if
tht_ rlllllJ(im
uJ_ll_lJ.
_.'KlUfZtJJy.,
I_l,r zl t'llndlilil
is_tlzl|_
tll_ [rt.qut_;ll_y
t_l)t:(2Ll'_l I r_1:_lt_r I. IId[I [_IU
;"|JUrJcf
trlln.lfoL'mti.;lrl_
_IIt|I11ZlLL'd.
[n r.i'du["
lor
U¢lulll:Jon_J
_ to ]|
to b_
YZ_lld,
It
clltl
hu
rlh0wn
|hilt
F'(It m
whuru
thu
conJutiate.
dlfforcl_t
eorr©lated.
II
_he
}l!n{pLi
follt,v_hlt_
} "
q
I'lPl.
r¢_fllllrc'ln_!n_
J "
I_
I:a{pll
ha,
}
q
[ll_lC_loll_
_noul_t_.d
with
1112
F
Lhe
'_ e
r/llht-
llnll
b_
uat|pl'l_d.
,
I;eiK" dunoten
zln IWt_g'llg¢! V.'_hII_s 111111thu hat,rink
I'qua_lu,
12
lu tlfltll_[|ud
_lzl loll8
_ltl tile: dnt_l
_ample
recorda
In _lle
I'inltu
Fo,vl_!r
Trnnlt(orm
Thin
con_litlon
e_ln he achlew_d
by appropriately
T_I© ¢rngrd_er
to
(12)
.J.lldlCllt(zu
fl _o_1_1_
,etime,t_s
n_en_l ch_
are
mu_unlly
un_epnratlng
the
|_l£-I'tltln_.nl_
_runnulrcn
r
113)
_lkla
uhcra
,
Xn £h_
dl,t_lle©
h©_w¢_n
tliu
t_o
m|crophon'e_
nn(I
k r - W(I.tH)
(15)
k_. - k/(l-r_)
(16)
aca the _nw
n,mt)_r_
corr_ap(m(Ilnl;
to thu
rl_lt£llil(|
]_/t-r_HInlll_
pl_tie_wh,
h_ cq,_ltL(_lt_
15 itn_l I|).
tlt_ wzw;! ii,mher
k lzs (hffJlled
f[oqu_ltcy
d_v_¢lvd
by th_
flp¢_d
of
nOUfld.
_lt_le
ch_ H_tch numt_(_r
fJ_
wlc_lCy
V dlvlde.d
hy th_
rlp_d
of n_m¢l.
*
5tI'|t:tly_
Lifo
_ran_fut'm
l'uf_t'i'cd
;"otlrl(zr
ilur;_r
comp,tllt
trmltiform
t¢) h_:rt.
Jn
_,f It rzlnlh_m
t'h_'
[Jfl[(;_
_6
i
|_1
h_n,.
tllt_na],
_'_)_l_'lcr
disc.it .slot
tt'l_n_lolrm
_¢_lvtt ¢tl_l_; th_
i'l |n the r_e_z.
ut_lrlt
hcclttlu(2
_1_¢!_| 111
'II11-' VZI[UL'U
Pl
lltld
_r
II 2.
find
Thuu
tll_
known
dJut_utcu
thu
l_u.,
l'al_lo
()_
k_. eilll
lll2r
l)t_ dl.'L_._rlTIlllL'd
lind
h.
1112_. rzm
IIt)w_v_r,
1112
LhL' i'rK}l_rt-lJ[ll_cl.rUll_
bu
lruIII
_orrL,
dui_rmlnud
I) j i
lu{loll
uulnU
It1 _'{lllilitQil
[J_lt_4.'l_l_
II12 -
th_
11
l) 2 I}lld
ful]¢tluI1
k r _Ind kR
_ll ol)taJllell
I)L'tWI_II
L°il_ther
dJ.[cc_J.y
{.111_ _IUCO 01]ett_'uril
wJ[h
from
U[
p|e
(1))
(:12/bl1
Ullln}_ tht, qU;IIIL|LI_II Ill't)vld_+d
hy t'qll;lliUllll
J3
to J_I
thu
refhtctlUll
c¢lul'fJUl_llt
_{I _iill IJiJdltLl_'rlllJllL,d
l'rLlfil
*'qU_ltl_¢l(If).
'lhlu COllll)llc;It|Ull
ll_ l'i_.|_it_vuly
uJlnpJu 41rid L'llnbL' L'L'lldIlypr_q_r,_millt,d
hlLo
l-_.,llih_uL
of Lhl _ ruf|l_(!t|.n uu_,l'fl_'l_llL.
LIIL,ilIlllJy_l#l"
to
_lL'l111 lilt
('ITIUII
t
l)ruvlll_ Zl dLr(_ct
._l"CH r ,i C_
_lll_IIC¢.'urllL')' lit th_
.C_&ltltlC
i)rOl)urLlel_
II'_l_.UL°ud
In _t duct
l)y [ll_
tT_1111l_l.'r--l'lllll_ll)ll
lllt_Lh(_l
I ll_ )_uVL,rlll.'lJ
I)y _IIII_ _ilC_O_l.
|a_lll)r_flllL
{_1' LIIC_SI_ .rl.
,IluCLJ_Uud
brl_l
ly
In thin
uu_[lox_.
/_ll _ll;ll
/Ill
_lthL'r
II(_IIIItlLIc
Illl!/llil_r_,lll_*lllt_
t
th_
KIJI_IIlII--IZ_--III)
l_y_LL'rnl_'ltllf]_l_
Th I-_ {Ill)hi
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tll_
ll_IJltfll_l_
/_II_IIII]¢_
N/ill I'pI_14_[ [U thl! |Lu'# i)I"l)/I¢_rlJllfi_ZlO_/ll_ l_lll_IL
lilt
,ufflul_ll_ly
hLillh
All_u_
for
Lhu fru(lUU_lcy
ra(tL(u o[
i:he m_llzlur_ln_m_,,
th_
dy/t.rni_
rnl_tiu
_ff
tile
_I¢'uuqtl_
IiIUllal_
,luut
Im
k_llL
_.l_llJll
L[lU alSprol)rt#L_
IIuJfl_..
'JIIu tl_lll_ll_l
II1" /-h_" /n|L.JllJlOIl_211 flI_HIL Ilu chuucn
"_LLII _II_VI_I'II[ _Olll_¢h_¢lltlonrl
illmJlld.
Hlcroj)lliJilt_Ii
kl_. ('_tuuJy _lli_t:_i|
_l_] CI'UIII;I_
l_l'rof (hl_ Lu LIII_[11_{:_
U|,I_L_(It" l_ll¢_
r_l_l_J_()_lIl(_lll2eEl
ll_lll)Ilril)*in
ll_liC4J_tllC_l)l'c_[_ell[ly_
IIIICll
nlJ[izrl)pll(lll_I
J:l
{IfHJllmt.'d
I_I)l¢it:ilrlllr_
_l(:()ilIl[_
+ pI*L'III_IIrL'
_lt LI i]D_II[. HIU&'I)pII_II_I_I_
UllalC_l tOO flll
_
illNlr[_'J_J _ll¢l'lldll,
C_ _XCUI_II|V_, _;III dJt_u_lllltLoll¢.[[IJc[_.
At /l'_lll_!ll_Ic_tl
l'_r
which ch(_,.i)(tu|ii_l
I_ _i hzllf-W;lV(,lUll_th c_L" LhL' uO_llld_ K:III_£WU J_iX_rolillOllCll
PlL'IIrlLII'{_
l_l?dtln¢lafiL
pllr_¢)lll_l)l" _.III_
llLilll(l_l_
WI|VI_ told LII,_re/]l!¢_LJ_)n ColI[f_c_cfll:
CillCUJ_llzl_¢l
['F(tT_ IZqllIl_JOllIt Itl_¢O_lUll InduL_£mJllllll{. _e..itlr tlmrlt.'/l'c_lill¢,,cll_¢l
_
wall iI/_ll_ntlon
tHld t_tilt/;itl¢_l]ul_rul'rl
_||l bl:c:urne (l._In41111z
In LllU rufl_c_Lon
CI)L'|'_J[C_UlI[
£111CIlI_IF_(_ll
lllhl I_ll'_L
_ ¢21"I"O1"11
r_llll{.
_CJ r_aeh a compr_,o.l,e
nrn_nfi
lh.ncz
(IJI'f(:r(:IIL
/_l_tor;_
Lh_ .p_lcllll_
.la).hl
I_ a_ Jella_
n [oh" d/z_m_!tera
of the
[l'¢qu¢ii_y, Zlllll
(:llll_),
Lo
tilll_I{(_fira]ImlJL1pla
[llll[Inl_
d{;m(lln
l'l_zll)'Ju_lon
u[ thu
coupled
with
;tdu(I._[_
t_ml_cr_lturu
il_luc_
reil._)nably lic{:._It_
of
tile ul)_,:d of
/_l}l_n unlt.
'l'll_._
_lt_d FJuw v_!loc_ty
uuu[Itl tlrn_i_
].tt(_r
re_li/c_ment,
Jl_[ormat|r_n,
_dlo_ld
l_l#r_llllL(l(_C)ll
c)f tll(*l-llll¢:{_n_ Ill2r iznd
11|2R,
'lhl!I'E¢'(IIII-_B_
r/llllll_
hl wll_.cllIICL'li£_I¢._
fll_llIlll_l_mL,
n_fi CIII_IlL'()I){.Jnl_ll
hIl¢_ Lo
Zl_:u;:_II {liltrilll_l(,
IVlll..l_
orlJy l)J/ir1¢t
h'llYUtll)rciI)ll_Jl{C
_ IiI [Iio lhlc{.
For _i
_._r_:lllilr
duct l_f d_41m(![l_r iI_ th/rl Implluu
thac tIl_ l'rcqu(,llcy I" I1_. {{i h¢
J¢lm th,ll
I)._tff)
(¢:/d)
wll|h_'
[I)L" n _l(luar*'
*h,.._ ,{
Md_
d. Lt .{mplli_._
LINI[
[ hn, t.
b_ lu.u
Lhnn ¢/Zd
wh_,rL, c I. _liu tq_l_(!d _)f el_lll(I.
•
P_
G_
IIIll {
i
_
_
All{: J.
the
^nllh)fi*c.-l)llllcnl
(',olwur_.r
_7
tll('rNtlr lt:_
"of
i
'i'hi_ui;iltJtlttcil[i*rror O/
[.hl_ ml_lilIUt'U[llUll£
_n ili_lii_ni_ciliE
on Llll_ coh_l.i_It_
ll_[_]l_$]U
IJllt_
Oll thc' numbel" l)_ Zwl_r_iiluli
uilud
|ri
tht_ UVilitJilthJn
of {.lle trilliiifl.r
[liliuLloo.
'i'o IlUitluve
cquiv;zi_iit
Itccuct_cyi
4i hil;h
ct)hurultCl_
ru¢itiJl'_!ll
l+uw_r iivL'lr;IKuu
I.ItiH1 _l lOW coht_rl_lIC I_ .
Ilnwl_velc I
LJtU i)!21_(_ llpIIl'ullch
l:$ _u rt_[)l_ill; thl_ Lg.u[ti ttii_[%l_ _ro_l_ti_;_vl_]y
[11o[,i_ _ivl_ril_i_/i
llntii
tlll_ fllllil
:euult
L_ eu_ulltl,lly
onliffeL'cud
hy tllu mlmllor
of llv_r_ltleu.
_)ULWI.'I.']I
[.hu
C;i I lhr.it
lilll
IlbtCl'(Jllhuni_
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"lhu I_iil IllrilLliill
lif
lhL, I_ilcl'clllhulll.
:i)'b{t'lllll
iu il¢:Colnllilllllitl]
h)' IllOUlitilltl
[;l_o
llill:l'¢lllhllilt.ll
lit il lilil_
in 11 lillllu
[li.ll
viln lilt l'lllhlly
Zl£lilclitd
Lu tliu illlUll
Ullll ol
thL* dii_t*
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tWO _ll_rollliollC.ll
ellli LIIIHI bl_ liUtlklll%l_ll to lie _lniziud
to
thu
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illlii
tli_ ti'llllUll_'i
_ /Ull_tlnn
_n_i0ul'_d
in tli[_
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l'Ulir_.ll_li_
tll_
rlttlpl)ll/ll_
(llutli
In llmllliLulle
lllid plifi_l_)
o[ I)lll_ i_lcro|lllonit
uyilt_nl
r_lli_/vl_
_(i _llu other
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If m/_rulihUllle
II
lill_[i_llll_l
of _il_li
will
r_iiuiL
wllur_
tho
lnlcI'oph_lit.li.
Ill
(llldl_ _'lfiilP_
lllhll_[lllllli
inu_uuremuli_
liubllcl'lpI;
Thl_
ilUtO-lipii_ti_il
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to tll_
folloWhill
of
i
llecllOllQ
tim
llOt
Of
trlillllf_
i*ilrllililOl
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_n_
11 i'Cfill_l_llCe I IlliCCl_linlVll
co_iwith
tliu llyll;l.'lll
O[ micl'oplion_
ti'_llli_for
c fl_.lliril
I_¢1Lllu eiillbf_lon
lic_ _
_l'liil_f_
flnlc_lonrl
lu
llcroplion_
[filllcorrecti_
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[(;22Jcorvacted
" G22/II112
fllllCi_lon_
[1112c,
II13c,
corilll_Urlll;iOli
i)[" tile
tlleil
iIl_C_ Lo COi'l'{ic_
_#_t_ln
l'_llliiinll_
I1
. ,,
l_lillurcll
(ill)
c
I2
(19)
d , (13;i/II113 12
c
(20)
[III2]CO¢C_CI_
d " 1112/1112
(2L)
" 11}.7/1113
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(22)
c
forlnll'of
thll lllltil-lllil.l:_[;i
lllll I _;['II_=_'C_ [llllCl_iOIIII
II1'1_ IIIll_l|
lit
l_f t|ll_ I_efl_ct[Oll
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_riill_nll_rlion
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lind otli_i"
lil!ollllltlC
prllll_rl.l_ll
ll_ iI iluc_
tl_tlt_l_l.
l|_l-illlhonll
ill
Ill
cli0_cii
l
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[C3]Jcotccctc
[lli3Jcolecect©d
Th_llo
Clil_l_l.'i_[.llll
[hl'
_ll_UJllt|lll|
Illtl'lnlll-lnl:Jlll_[ICii
/I) Jtl I'hulluII
llli
I_i_rolllilHill
u#tltul
ill|
_11_ r(!/i.ci:nce
uyuLera.
/:_,/ ¸¢
, .
10
lnlltrltgl_llt_ltlun
;llltJ
Atmtlct_ltud
iqetlJttlrt!mollc
Protedtlreel
The JnutruJllClltflt.|on
rt:qllirt_t_
to pcl:forf_
In-duct
ctcou_tic
fnellott£clneittu
uuLn_
the
tr_mu[ur
furtctiOll
technique
In tdluwn rlchut_aticially
In |:Ifittru
9.
A rtltldomnuhtc
i_unurator
lit COUlJ_ed thruu_h
zl I)ower
;l_=llllfter
to _.l tlcouutic
driver
u.tt
iliid I_en_r_ltuu
ot_ml_tic
!lli_lmlO
In tile
pipe,
The
Inside
dt_im_t_r
of
the
i)Lpe
mtud
t11 thL' e_puril_h!,Czl
WriSt _l ri_ll, _tnll b,3_
[_a;i (]/l_')
c|lanleL_r
Llrttul
_lnd
KJaur
cutlduimer
micrt,plm.e_
were
ml)ulttC!tJ fhtuh
with
Lhe lntzLd_
wtlLi o[
thin
pLpe,
Fuc
thi_
pipe
dl;]metor,
the
upln_r
limit
of
tile
frequ_llcy
ranse
In
tci|lch
Ollly
pllltlu
wl_v_u pt'Op_l[_tltO
IZl I_ hJlz,
_'or
tht- _ trifler:t
JOlt coefficient.
,'In ztXIGI
I_onntlrumetltos
ulllzcln_
of
27
,_m w_=_
uoud
butwuetl
the
two uptltrt_l_
microphonuu.
TIitift_ tzccordlll_
to t_liUlltJUn
].l_
the
[It.:_
Ind_terminnliL
frequency
occult',
lit 6.it kill _hlch
I_ albert., the
frequency
ritll_U
o_ Itttt_ru_lt
In _Jtg II_ltdutt:InL_l_t_l.
I% third
_lcrop]lOll_2_
illotllltud
tl(tw|lutr_ltril
O[ _ tilt! lllX(-'lIC_l[* t [IR(I lill IlnL*cJIoIc
I)tpu
turlnl|_ittlolt
._I'_ Uuud
In tim trnnnmi.nlonIOLIU ml211ntlremUl_tI_.
Th(_ nll_Cholc
terl_llllitlu_l_
_,tJllCit {:oIIUli_tGi
Of ¢1 IUtll_ 'dutll_(I
of
a¢outlt.lc
(|bt_rl_lllts
within
zl _l tr_ diameter
pip=.
pr_wnt=
thu
[orr.ltltlon
of
dt._'notr_ll_
r_lluctccl
wi4vell
.1Ild tJltl, pucrnltu
m._'tl_ugcln¢llt,
of
t.rnntnilltt_2d
H_lveu _lttl
t}llly
Olle mlcrophollu.
I[ /_uc]l _| tEtmill_tIo[I
141_1"_ [lot. uIl_d I t_o
du_[llll_fui_nl
m_tcropJltlnc2t_
could
bl_ tll142t_ Ill COllJunetIull
tdl_ll
thl_ t£11nOl't_l"-funct_Of_
EUCIIIllqUU
t.O (Je_tJmJlt}tlt/ tile tlo_llutl-I_litn
IltltlltJlll_
Wltvc to iJ_terlllIgll
tile
t It'JlnBml _ltl Ion
lo11_1.
Amplified
Annly;_er
nr_tirum_nt_l
mlcruphunu
=lI_nalu
weru
f_d
for
mt!4_nttt'_mcnt
af ii_lt(l-npc_tl'_t
ttt_
|*U_red
on the
dtL_lt_l
(ttodel
to
an lip l'lerlln
and
trannlf=c
tttp_
,nit
btillt
trod r_cnllud
for
tltlbH_t_klCIIt Col_lptltlltlOil/I.
'_Jl_ c_lJtlr/ltlOl|
wt_r_ I_un;lurcd
t_aln_
i)lll_il
or mltropll01Z_0
all dcatt'lb_d
In
II¢ICtlOn
_11_ tided tO i'_(J_l[y ttlCt _lUtt)-b[}_CtrtZ
rind t_ilntJ[¢_
to ml.ntlonu
I_l through
22.
Tile
f,nttlon
vt)J.tnSea
1112 r
nnd
almlllL_llltl(I,,ly
1112_ w_lTt_
Ill
bo(;h
comptlt_:d
Input
by
clmnn_ln
fly,din8
of
1_5_20)t'..rt©r
ftm_tJotm.
lllt.o
tll_
tr_llll/ur
[uIIC_lonR
tim
cllJtli)tntJotl
fu[tctI0n_l
iiccordin_
Gnun_lnn
Ill©
Thuut_
_lll_lyI_
nnnlyxer.
wllItn
noI_©
Llmc_ d_lnytnB
,n_
chnnn_l
by -'krn/*_
nnd kl,/_,
r_mpoetXv=ly.
(Aecordina
to oq,lttl.nn
13
_md It*) nnd cutup,tin8
thn trnnefcr
function=.
Thr. microphone
_p_ctnK
o[
27 Irm WOe Clloncn
tie that
thgll=
time
dtilay=
(both
tq.al
to
7B Iln) w=re cqunl
to
tile
time
domain
renolutl_m
of
tim nnnly=©r_n
^I)C unit
for
th_
_.2 kll_
/ rOqtllsncy
rnn_o,
Tile comptltatlun
of equntion
11 w_tu pctfot.ml:d
completely
within
thtl nnnty_er
unit.
Thurefor_t
npuctt_
of aCOtltlt_¢
pnrametern
ntlcil
n_ r_flnctlun
co_fl'tctentn_
trnnnml,nlon
Innnun_
_te._
cottl(I
b(_ dlnplnytld
(lir_c.tly oil th,
aonlyxcrmn
o,clllo_!copu
_tnd/or
nn n-y
plotter.
The nlmpllclt_
of
the form
of
,:q_mtlon
U
la a key f_aturc
of
thin
tcchnlqtm
nine=
It
p©rmlt=
Immediate
display
of
tile. I_lt.nnllred
nco_nt_tc
p;irilm_Itcr
In thn
lnborntory
wltllo_it
r=_Jo_ttliR
to
n pr_-pru6r_mmed
dlRItnl
cor_)mtur.
'lwt_ _l_i_rttl1_i1_L, w_:ru L:oIld_ict_ll. _f_Jl:_n
B th_
nwl_.H_u
hardw_i_¢
L_}l_i_]u_
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qui_i_y
_:_:i_|i_L_
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H|2r
l-cu_u_I_y
{lurn_lii_L
tt_i1_l_rJ_i_ll_,
r_li1_L,.
by t]_
li|_:Ji_}_,
I|
thu
r_uu|_J
_hL' _h_}ry
iu _:c1mi_|_ , i:i_ur_
/_L h|_|_
_i}_j_ru)_l_l_l:
']'y}_Ic_l_y,
|h_i_]_y
L_ _t'cd_'_
l_i_l_rl , _0 _i_}l
_rr_,l__li_L_ut_
_,ild }ILZ _ cili_u_J
_11_I_,i_:r_p|1_
lil_d o11 _,h_[_ty
Lwo-we_:k pi_rlod
[h_t
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10 i_r_ul_z_u b_)_h _tl_
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v_hJe_i _J_J _r
_hu I_}}_:d o_ ,(_t_n_
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llII_:_t,i'/Ic_l_il
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in
I_pI_LJL_]L
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i
12
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Above _ kllz, LII_ U_lZ_rJnl_iltzz! r_oulLu
I'_ll] [dr below Life th©orut[cal
I)r_Llictlol_.
Tilir_ lu h_|[uv_d
LO bu du_ Lo the uceur_t.;ice
u| Lieu [irtlt
rJllll_|
cl:QzJll-,uJdll wit_hill Lhu .llu,cu'r.
"|he lowuuL fr_ql_l_cy
ut which
mode w[|l
prtlptIj_zzte _n,tLullU_L_cd 111 Lh_ ch_[_bur II_ K[vt_ll by Ill)
t -
T}lv
Lh_oF_.,LI¢,IL
mllnB
the
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C_t[_tilllt_otH_
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do
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ilUt
tilf.*
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t, m(.)
m
--
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d
t-/itv_
Jmpl'OV_
,ItIHiI:IuII.
chzlfzlhL'l"
(]./_2
.
reflucI.ed
I._£cztt).y
_t1(_
to
CoCr_cl_lon
O|
"n'l)llJd
Vdthl_
(l.22).Ot,
,lb_
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.
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(2_)
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fllod_:;.
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pipe
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dll_t'_l_llt
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tidied
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_hlel e[lect,
n _)d|fied
I,hl_o£ul;JCll[ cUl'VU
|',c phll,_ |r_ _Lhown In I'lFlllrc
12 bcLwucn 1.1 kirz _,d 2.7 kilt..
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Lh_ J.,flnl_e
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pLpu ct)rtectl_n
,|._l_htly
ovurc,L/.r_._¢_
Lhe cucrucLJoll;
hc)_uvc:rl
It
c_mp_ll'il_Olt
tll_et_
t)i_
¢!_l)erlmcl|tnl
FIRu_'_
_1
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tcchnlqt_e
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In
r_/hall.
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l[J_
(T|.)
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to
L]l_ol'y
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mlcd
clan
d_ltn
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dllll:o_tlpl_[Fdl
_
re_z_L_
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I_l]lltl'u_lll_
fol'
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to
check
_pt_nqiur.
nru
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che
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to
lliJeFIcer
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111 l.hL!
11_ptC_llrlion
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wiit_t'_
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dO'_l_rlLl_ullri]
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jl¢_dJc_lOllft
g) _11_
(25)
or
(if
fur
I.htl
|_.IcTICC_*
I_['_lllllmltil_Jun
(lul_rLcc-'H_tvu
t_pon_lbl_
I:h_,
']hl_
tel_l_llltnen_
I.IIM
)ob_
u(_rt4ctslr©
Z3
fornl_d by Lhc iJrotruo|Lin
of thu e_Lt
pipe ll|to
[he ch_lmbcr,
The dccz'e_lue
IJi Lh_ _sp_r|_utlt_l
TL d_tl_ nbov_ 3 kllz In du_ to the _Jccurrcl_ce
of [:lie
[J.rut
r_llidJl crot_-Ln_dc
wlLhLit Lh_' ¢lt_zl_lhcrB a_ discussed
_arll.er
['or th_
r:_[lect.Lon
coet'[|cLul_t
dal:_,
'rh_ _JvurlLl[ Lrund _J[ thu _p_t'Ln_cn[_l
TL dlll:e_ [ollowu
that [_[ Lhe Lh_:orutLclll
pr_dLcLLun,
II_w_wr_
Lh_ n_duu_cd data e_h_hll_
['lu_tu.aLlu_u
LhruughL_ut the
ftcqu_'ncy
ra_q_, whlcil ,ir_, I_OL_lc¢o_lll_,_l f_r _y th_ tilbury.
Althu_q_h thu
_t'll_[it _s_ tll_::_ [JLl_:lt_tL|lJl_
l_ IIOL _llU'_ll_ r_l'[_2cL_d W,W_B I'_LIIIItilu _lll_lto|,_
_J_Lcllcu[" I th_l
_3_1 uucd Li| uqu_L_l
2_ _u_ld
ho _.l_ ct_'_r _h_ LL_thu _¢andini_
wavu p_Ltt_rn_o
Th_ _J_lJouLl_ted urrur
In TL wo_d
h_ o_ th_ f|_lctu_Jt.LiJl_ n_[;Lir_
ul_lllll["
Cu ¢h_ d_lt_ _f FlSu_'_ |:_ due _ the prcuencc
of prul_ur_
i_odu_ and
I_ltl:ln_d_
_t[: Lhe Llowl_n_ruz_n_ _nicrophul_u
[uc_iti_l_,
A _¢t_dy u[ Lhu itcuu_lLl_
_111
ba COlldUctcd
ll_ /_ltt_r_
_[_u,
COHCLUI]IHG CO_EWI'S
_lld of _ L_LI]. pipe Lit lln l_purc;_ln_ tupl_ Ln _hnu_C: Ilolu_ _l_ud_u_ _t_d tile
|l_u_lbilLLy
_hnl_ _hu nco_l_tlc
p_en_uru [l_ L|_u I_i[_ hill), bu dirL, cLly rulaLed
Lhu radiltl_ud uound t_hould |_ [u_'_het" _nvuul_l_i_d.
The Lr_l_[_l_:uL_ct.|_l_
tu_hl|_,qu_
d_velupud
b_ eli con_ld_rd_hl_
1,
hy (;M ]L_ruh
Lcltlorator|_n
u_te |_ol:h In_ _lu_ul_t.
_pp_lt_'_ t*; pr_vLd_l
uyu_,c_ _l_vuJop_l_llt
to
[ol_ thn
_Ll_| [o_" |_u_lnlbL_
H_,_t_ [low
._lnc_! _h_ _f_]n_fc_r [Lil_c_,to_ techl_|q_
_tn I_ L_B¢!dwith I_enl_ fll_w I thai: ¢'[fc¢_
_)t_|d I_ _cc_ullLud [l_r d_tr_cLly
ll_ _l_y h_n_h turL_ _4_Ll_i_th_ L_¢l_ll_lu.
A_I [l_r
_t_l I_h_ f_¢l-[l_lt'L L_l_rllL_lr_l
_[I-_Jc{: |t_ _(l_¢:_rn_d D [}_l_ch _ul_ll_
_L_ i_;m I_m|_l'_l_r_
w_L_Jd _l_ro_h_c_ _ r_ll_cl:|lJn
lt_ Lh_ _pu_d o1" _uul_d f_'¢_r_ th_
I'_r the
it_:tunl I_l_h_'l: _.rnl_url_u_'_'_ I nnd chirr _'ffecL cl_u|d h_ _l_:c_l_t¢'_! ft_r I_y _
_h_ uf[_c_
c_l' ,,cmp_ri_ul'_:
Ilr_dL_nl_
in I;li_ li_h_un_: _),_(;r_ I howuw.rl
62
lu tl_
;
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I_ll_ltllll_!f
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I_u_|_'_t_d
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th_
L'_lllllL_t
I _'_Jl_
th_
,lll_!
II_t
L;_!
I.h_t_u
Lll_|_
_h_
b_
directly
it|i_u
i_[pe
Iml_'d,_nc_,_
_rl?
_ll_Jul_l
h_
i_ll_ncuru
hvll_h
d_l_c'_
_r_luun_:_-du|_ll(|_l_
uf
L_t_t_d
th_
du_'_lmu
nlru
_t_ nolu_
_ufficl_nt
dlru
(Io_n
uf
nnd
_l_u
lr
_?_-lturl¢)n
pipe
|evL_l
due
_orker_
¢ovcl"
t
_lllt
_lu[l_ll]y
_f
to
hnv_
I:_j|_l°
Ju_
l_ll_'_hlnc_
thu
I
Itl_i_l_
r_ldlntud
l[lu_rtion
i_(
_ltten_l_tud
Ih_wevt'r
I;h_'_olnjlIu_¢!
tl)
I
rlllll_e
l_pc_ify
_hl!ir
ill"
¢_lldJtlOlll_
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I.r_lnuml_UiOl_
tll_J_!
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to
th_
frl?_lUOl_Clvll
Ih,_'_lu_J_
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vL_h|c[_
tllur¢,fur_l
t_uL
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ur
_J_IILII_
ilul.
lit
zl_lrnmllry_
bunch
Lh_
|l_hld_'
u_l_'d
l't, lluil_llll_
pL_rpu_uu.
t_ll[
L_[ut
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tl_l_l_
Jlnp_d_lH¢,_?ll
I'_litl|ttJ
hi
¢_l?l_Lir
(nr
hi
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uu¢.h
(l_|rnl|nlr
vuhlclu
IJ_
ii
il_
w'_th
avai]a|_le
iInturu
I
63
tu
tlulu_
ruduetlonu
u_hnul_t
_yut_n.h
_vlllL_lte_l
corr_hltlUl_
[11
y_
on
can
_o
curruhlt_
_ht_nud
l'huu
vchlc]u_
hu
noll_
t_J
hu_o_'u
dutur_nine
u_Jtnh}luhudl
_lr[tu_|_l
n
_lrv_
15
l°
Lt'VJll¢_
D II*
_lnd
_cIIwlll_l_r,
LhlfJlmS_d ClrcLJ|zJr
Fubruary
15. 1966.
J,+
Pipe."
'lUll
thtt
IIzl_iit|un
tl(
IqlytJLcu RL'VI_Wl _qi].
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"The ItadlllLlon
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Vul. 1"J, P_I_.6+ December 1970,
1975.
chap.
7,
pp.
302-361,
J, I_Hcy+
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A HETIIODOFHEASURIrIG
EXIIAUST
SYSTEII
IIOISE
tlinelchi
Inagavta
Trucks& Buses EngineeringCenter
fHtsublshIflotors
Co.
In Japan,noise regulutionfor motor vehlclesIs elltheverge of
becomlngthe strictestIn tile_mr]d. Tilenoise levelof heavyduty
trucksand buses will be limited to underfigdU(A) from the present
09 dB(A} by the ISDmethod by ]979,
Figure] sho_isthe contributionof eachsound source to tl_etotal
noise level of Japaneseheavy duty trucksand busesmeasuredby ISO R362
n_thod. The enginesof the Illustratedvehicleshave from250 to 300
horsepower outputs. Enginenoise is responslblefor tilegreatest
percentageof exteriornoise. Exhaustsystemnoise,and coolingfan
noisecome neat In order.
Our bench test on mufflerscan be c]asslfiedIntofour types.
(I) Measurem_.nt
of AcousticAttenuationof a fluff]or,
(2) Measurementof Fiow-Generated
llnlse
of a lluffler,
(3) £xhaustflolseTest on a StationaryVehicle,and
(4) ExhaustIioiseTest on an Engine{]each.
(7) Heasurementof AcousticAttenuationof a _liiffler
The setup of the measunlngsystem is shol_nIn figure2, The
outputnoise Is r_ea_uredIn a c(lhlcanechoictest chamber, Its dimensions
are 2.5 metersor 7.5 feet on all sides.
Input sound pressureto a muffIeris controlledconstantat
110 dB(A), and as a noise source,slnusoldalwave, l_hltenoiseand
taped spectrumfrom the exhaustof an engineare used,
Obtaineddata Is recordedand post-processed
hy a coniputer.
Figure 3 shows our _layof expressing"Acoustic
Attenuation".
Tl_edifferenceof noise level between U1e referencestraightplpe _dilch
fl
r
Is referred to as the _I0use f_ode]
, an(lthetestedmuffler i.,
designated
as "AcousticAttenuation",
An exampleof frequencyresponseof the "!lase
flode1"Is shn_vnin
Figure4 In order to comparethe fundamnrltal
e]emeotsof mufflers.
In this case, the equivalentlength is ]75millimetersor 6,g Inches.
N
1lie fundamental elements co.ft(Juration and their parameters are
illustratedhere (Ref. Figure5), Though the expansionchalwlber
tyDe
and the resonatortype muffler se_111
to be themost popular,the multihole type is _Idelyused and revealsan interestingfeatureiJhichI
will mention later.
Figure6 sho_Jsacousticatte_matlon_,d_tchI mentionedearlier
in relatlonto slnusoidalwave, Irehave shove an expansionchamber
type here as an example. This exa_T_ple
is a very simpleone-chamber
model, In this case, it is meanhlglessto illustratethe measurements
and calculationsof frequenciesabove2{]0[}
llertz,
Figure7 sho_isone responseof the resonatortypemuffler, As
tilenumberof holes is increased,
its featuresbegln to resemble
tlloseof tileexpansionchambertype.
{_ex_is shoHnan exa[$Jple
of a respnnseusleg _dHte noise to
comparewith thatof sinusoidol_lave.This cG_nparlson
is made idth
tllemulti-holetype muffler{Ref,Fl_lure
O).
The attenuatloncharacterlstlcs
us|ng slnusoidalwave are
representedby tl_edottedllne andtl_oseof tileI/3 OCtaVEband using
_hlte nolse are shown by the dots, in suchsi_nple
_odelsas thlsone,
the I/3 octavohand noise Is sufficientto illustratetile
acoustic
featuresof the muffler. Nhen whitenoise is the Input,an attenuation
at frequenciesbound _ k_Iz,and overa11,are obtained,
Figure9 shows tileatbenuatlen
characteristlcs
of an actualmuffler
for a vehicle. All the mufflershave a diameterof 200 m. and arc
I meter in le||gth.Freqaenclesof above 2000llzare best atteenated
by type C. TileA-snalelevel a1_oshahs Uie best results, figure10
shows an exampleof acousticattenaablon
wIUI respectto a _dn muffler.
When the actualexhaustnoise of Uioengineis used insteadof white
noise, the spectrum poses a problem. Figure 11 is the specbrnm of
tl_e e_haust noise from a VO 14.fi liter dtesol enTHnewithout a muffler.
Tllls2400 rpm spectru_l
resemblesthatof _lhltenoise and this_las
used as the sound source,
The acousticattenllatlon
of thenoise of a muffler|Hth wlHte
noise Inp_tand the noise of a n_uffler
wlth actualengineexhaustnoise
Input blarecomparedusing overalldl_(A).The differenceIi_acoustic
attenuationdoe to the differenceIn Input spectrur_
was sIIqhtand
good correlation_as seen. Accordlngly,
_ledecidedto use whlte noise
|nput for acousticattenuationstudies.
(2) lleasurement
of F1ow-C_eeerated
_Iolseof a Haffler
As a fl(_ source,we used a rotaryblowerand a normalair flo_
was supplledto the testm_fflerthrougha silencer, The flo_(generatednoise was measuredasin9a cubic anechoictest chamber.
The robe_ry
blol_er
used, had a flo_volumeof 54 m /m|n at 200 e,nll.n
in order to simulatethe exhaust_as flo_at full load of a 300 horse-
power class dleselenginewhich _lemanufacture,(Ref.Fig_re13)
_0
'
Using thisequipment,we testedvariousmufflersto obtain
thelr flell-generated
noise levels, (Ref.Figure 14)
Tile change in noise levels according to the differences
speed were as follows;
in flow
Wtlen flow speed Is less than SO m/s, nolse level Is proportlonal
to the value of V to the fourth power, ||here V represents Ule flow
Speed.
|}llOll flow speed is less than lOO In/s, noise level is proportloflnl
tO tile value of V to tile sixth pol'/er, and _/llen flow speed is more than
I00 m/s, noise level is proportionalto the value of V to the elghth
power or IllOre,
|Indiscoveredthe followingtendencywhen testingtlm fundanmntal
elements of t e muffler (Ref. Fl!lure 15)
Tbe flow-generated noise
showeda tendency to be hlgher in Um expanslon chamber type and the
mulbl-bolo type nluffler,
I would like to show typicalexamplesof tilespectra. Two tendencies
_mre observed. (llef.Figure IG), First,as tileamountof flow increases,
thedominantfrequencywas seen to rise to |be blgherrangeand at
the same tlmenoise level ts increased.
In tilecase of multi-holetypemufflerstlm noise levelgradually
increased,and as yOU can see in the figurethe dominantfrequency
is above 2 kllz.
Tim flow-generated
noise levelwas evaluatedtilesame as acoustic
attenuntionuslngdifferencesof the levelsof tiletestmufflers
based on the straightpipe. (Ref.Figure17}
We testeda typicalmufflerand found that In mufflerstdllch
do not producea whistling notse tile flow-generated
noise level
remainedconstantwhen the amonnbof flowexceededa certainlimit.
(Ref. FigureIB)
Next, the correlationbetweentiledata ebtnlnod using the flowgeneratingequipmentand exhaustnoise of the actual veblcledepends
on the correspondence
of alr-flow, Tileeffectof englnerpm and the
temperatureof the exhaustsystemwas studiedusing testingequipment
for tileexhaust noise of statloeary vehicles. I will mention this
later. (Ref.Figure19)
Tiledifference In temperablre between the inlet and outlet nf
the exhaust systemis from200 to 300 degreescentigrade,and wllen
tileback pressnreof tiffsflow-generated
noise and thatof the actual
vehicleare compared,It was found thatbettercorrelationis seen
when tilerate of flow ts convertedat tileoutlet temperatureof the
tail pipe.
I
1
I
I
i
i
From this result, engine rpn and the exhaust flml rate con be
approximatelyrelatedas shown in Figure20.
_hen correspondence
is made at the outlet temperatureof the
exhaust system, the actual exhaust noise and the flow-generated noise
of tile vehicle, when compared in tile sareemuffler, ts as shownin
Figure21. And in this case, the flow-generated
noise accountsfor
only a small percentageof overa]lexhaustnoise.
And a]so fr(znour experience,if the muffler is norma]and does
not produceany whistlingnoise,it can be said at presentthat
flow-generated
noise contributesonly slightlyto overallexhaust
system noise.
(3) Exhaustl_oiseTest on a StatlouaryVehicle
Figure22 Is the layoutof the testingequipment.
The baseof this testingequipmentIs a heavy-dutytruckof a
maxlmmnpayloadof 11 tons,equippedwlth a 305 horsepowerV-9
dieselengine.
An EddyDynamometerwas mountedon the rear body of the truck
and connected to the engine through a transferto absorbthe engtne
output and also for automatic speed control of the engine.
For tll]S
test, theexhaustsystemwas mounted at the side of
tile vehicle and a sound insulating wall was set to avoid the influence
of enginenoise and other noise from tilevehicle, flyasln9 thls
apparatus,radiatednolse from the exhaustsystem can also be easily
evaluated,
Figure 23 shows the changes In the exhaust noise with respect
to its temperature. The engine was operated at the speed of its
m,_xlnlum
output,and the levelof exhaustnoise which is represented
by "t_L3' in this figure, goes up aS the temperature rises while the
level of radiated noise goes down,
The change to the spectrum is shotm in Ptgare 24. For the exhaust
noise, the spectrumbelow 2000 Ifertz tends Lo rlso as the
temperaturerises. And for radiatednoise, the spectrumabove
1 kll_ tends to decrease as the temperature rises,
The Figure25 shows a mufflerwhich was shown earllnr. Thls
figure showsthe relxtlonship between the exhaust noise and the
back pressure when different arrangements of ptpes, tail ptpes, and
sub-mufflerwere applied to themufflersho_n earlier. From this
result, you can see that a difference of a fc_dfl(A) Is seen when
the exhaust ptpe and tat1 ptpe are arranged differently,
82
Tile re]attonshtn between tile back pressure and the attenuation
is Inverselyproportional,Hben ome increasestheother decreases,
and tilequickest(fastest)way to acIlleve
sufficient
attennation
without raislngthe back pressureis to carefullyadct
another
nluffler.
The relationship
between the attenuationof stationary
vehicles
and acousticattenuationwhich was mentionedbeforeIs shmm in
Figure 26.
The solidline shews a one-to-onecorrelationratioandas
you can see, there is bad correlationbetweenacousticattenuation
by while noise and the atLenuatlonby using the enolneof Lhe velHcle.
Tileattenuationon the vehicle is much greater.
Wl_enLIHs is comparedusing the spectrumIt canbe expressed
as the fo%lovllng.(Rof. Flg.re27) In the attenuabion
spectrum
obtainedfrom the engine,attenuationabove 2 kllz
tends to Increase
comparedto theacoustic Lestand on the conLrary,theattenuation
of thespectrLm_
near 500 hz tend to be m.ch lo_,ler. At presenL,
we #lavenot been able to explainthe C,lUSesfor tlle=e
phenomena.
And %his will be the objectof furtherstudy.
(4) ExhaustllolseTest on an En.qlne
blench.
The method of measuringtileexhausbnoise in enginebenchtest
Is specifledb¥ the Japan IndustrialStandardD1616, (Itef.
FigureZ8).
Tiffsstandardspecifiesonly bhe microphonelocationand the running
conditionsof bhe engine, buL we have also consideredthe lengthof
the exhaust pipeand the tall pipe. Also ser_onw._asure=
shouldbe
taken to avoid tileinfluenceof radlatednoise from theexhausts),stem,
"La" must be equal to bilelengthof the exhaustplpeof theactual
vehicle, and also "Lb" mast be equal to the length of the tail pipe
of theactual vehicle.
Themicrophoneis sob at an angle of 45 degreesanda posll:ion
of 50 centimeters
.withrespect to the exhaustp$pe axls,
The engine bench test, in essence, is the same as the bench
teatof the stationaryvehicle_lhlchwas menbionedbefore_o the
correlablon between these two tests were not checked.
Figure29 shows the relatlenshlpbetweenthe abteouatlen
and
thehack pressureof differentenginesand a variablonof mufflers
on the bench test. The figureon the right shows theamountof noise
ntteuuatlonand the figureon the left _hous the beck pressure,
They both show 9end correlation,
tlD
m
The engines coluparodhere are the VD pre-comhustion chamber
type with a volume of 13.27 liters
and maximumoutput of 265 horsepower and the VO direct-InJection
type with a volume of 14.8 liters
and maximumoutput of 305 horse-pox_er. Nu regret that we did not
make any comparison with the tn-l|ne 6 cylinder type.
tlext, Figure PO sho_tsthe relattonslHp between the exhaust
noise of the engine bench test and that of tile actual velHcle.
/_nd tn this case. the relationship changes flreatly de_endtn9 upon the
ratio of the exhaust noise to the various otlmr noise of the vehicle,
For this vehicle the amountof exhaust noise on the right side of the
vehicle ts about 30 percent, The upper line shows the acceleration
noise measured by [SO method_lhen the m|crophone was set at 3 meters
from the center of the vehicle, and the lower line when themtcrophone
was set at 7.5 m from the center of the vehicle.
Ne have drawn the conclusion that the most practical method of
m_asurin9 the noise fron the exhaust system Is to use tile engine bench.
Ilowever. sufficient
consideration must be given to LII_ length of" the
exhaust pipe and the tail pipe. also it ts necessary to consider the
Influence of radt_ted noise, and to estimate the level of back pressure.
_4
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rifle w_lhlwhl+: prnl_l¢m ol t¢dxicmS city If.lll+c nollm h_t incrcJ+InFl)' ,IrJwn lh¢ att¢flliun t)l" iTl:erly
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chal_¢ o[ _I udyil1_ Lllf/L't¢lll _'lh_) _lCrll_ _l_¢fl :I_ CH_Jl_e11_II_¢,_llohfll'. _)'_I¢I11 nolle, CXh;lll_l ',_')l¢In rlO_.
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CtJllIIlally ]It*l!all wo[l.ilIJl Ofl l]¢v_JOJlilll! II'_ IlWll ]OW.Hqll'i¢ II_OIU.I_JI¢lllt_.k.
In llli_, ptoj_¢l, lh_' r_'_*;_[¢]l al,_J lh_l Mil_u]11_lll _V,l_in ch,_l_c of tlol_ tCdL_liutl ul" lhc ¢,l[l;lli_l
sysl_m. _Y¢ wcf¢ _hl_ Io ohlain _l_h_IJnlJ:11l¢_ulls _IL_rJ_IL:
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2. COI_TI_NTg
OF INVE_I'IG_TION
Ju sludylng lhc cxhalL_l sy_l©m nui_"
lukilll_ ]III_ L'oll_id_l_lioJl in d¢letlllhlJlql
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2.1 T_rJ_l of_lud),
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lh¢ la_/_¢l aliJ ¢OlldJlJonl, "l¢_I alld i¢i_ir¢_i ',w'l_ ¢oHdl,¢lCd
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1"yp¢ oi" lllUf[l¢l:
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l_llllll, I Ioi of l'llnllllllCfllnl
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lh© ¢_lhnl_ll lyllcrn, _llo Io _l_p lhc l_dJ_l_d noi_e Jn lh_ Vclllcl_,
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3. FLI_M£NT$
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oulct Ih_ll _[ Ihc r_lllf_¢r _rld Jcp_r_lE_r _1¢ ¢l_n|llu¢l_l
Io pcllnll iplllll_8
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Typical
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The m_n
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The
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In lh_
ph+ncw_vc
J_ d
I¢1 us _l_mtn_
y¢Io¢11¥
which
l_ml wJlhot4(
ul'wtly_
moliotl
Illv¢ll
In prl ._;1_1 dltc¢li(lfl.
111_ IlIiIINCTJnSIglIcd
t_dl_lhln
_t lh+30lll[cl
_}_ U;
optlli/lfl
p_vwct
.llld
at lh¢
/_dl_li_*;l
oullcl
5_iill+lll_C
Ii
|l IIIc ouilct
by I1'1, U!
t)llVrlt¢l_ by I+'I+ , a0d th+Jt wilh II1" IIiLi[[[l'r, Ih_
IJ[:loI_ +lit I_'_p¢ctlvrJy Icpxl'lcntz'd
a]ld _1 , i'_¢tlLl_ll_: JilCJLil_llOJi ¢)1̧Ih¢ Jlltllllcf ¢all I)_:cxplcs_¢J a_;
I *++
U '
/+tx'
I'1%$11111illi_
Ij,;It /' $h_l','. :ill rlll_ _'JjUt' of _oIillL_ Ill¢_llit._. I! ,11_|111_,vJIO¢ OI lh.' _t)jlllllL" %,'h)_'ll} tl_
W,_L* I$1LIILtlII,_*I11"11_
] lh_" II11_*ILIIIL'I[ilIJ_Jntl ',_11
Jl% _ lilc _lllLl¢l oi+¢11111_
, tJi_ 111,1¢lix@Ilh¢ t'%hJLiZ[ llli_c
b,,]It,
I'_'
'['h_ nl_llj_
,.
A'
lJ'
P+'
...............................
,:,
of II1_ wlloje c_ill_tl_l jli]l_ sysl,:m with Ih¢ ;11u[I]¢: j5 [cllxc_nIcd
_:
[C,][U,]
.......................................
("
L_[ Ill coll_h_r Ihe ¢a'_¢ Ihat wllCn (lie _olllld _olll_c Ila_ a Cun_bqlll sa_llm_ Ilf¢_lli'e, l_s lotlnd Pl¢_ul¢
do¢;s n_l ¥;11_'i',:l,,JId]_:_ CJ_ill_lallatltln ol Ih¢ IIIs1111_"( Pl'" PI) alld Ihal I_di.lil_lll Icllsllm¢¢ al II1_ Ilul.
ICI oll_.'l_hlB Ill_, ¢lho itn cKlllCs_lon ol I/_+ _ A_) a_ al_ a_.llll)llom
|!llu,(lioll (1) will I1¢:
,4ll".'OIO_tll-21Jl_f,_ll'
...........................
(4)
Ilcrl¢_ jl" v_IL¢$ II and 31' _r¢ follml hy alll)_liI_ith_ all clcCIri¢ ¢il¢llil lot the lll0111x o1" the wh_l_
¢_|liluzt z)+Sl_lll, all¢ll._li(all
,_an I)_ ol_l;lhlCd,
]:und_m¢ltta]l}' slle:lklllB, w11_11
@, ('+ _ and I lc_ll¢_liv¢ly r_l_t_cnl the _l_ll_ily o1"m InCdltim, ¢:l_h
I_lc_lll v_lu¢ of _omld vCjo_:lly. II1¢ 5c_ljon_ll ;1_¢ilo1" IIIC [lille, erl_l IlJJl¢ jmlll]lh with Ih_ ])ill': ollcned al
bolh Ol_llllli_l+ Ihe [(Jllowjll B liq_l_tioll i_ _i¥¢JI.
[2;,,. +,,.
Y/h_rl Ih_ PIpe do_cs .I one oPcnin_, Ihc ¢q.nlion
j_ ¢cp,.'_cnl¢cl ._ followl.
[j. .J-I,:+
,,, , .o,,°l]
..........................
1°,
.AllCnllnlion
Indl_lnll
i_¢_l¢llllt_l
Cqu,0on
b}, oblnlninl_ v_hlc Is _.ll_[llulinPl
(4jhasc_lon
Ij,./(eel_,j_ln*l,
glvcll/tom
cq._tlon
(_)and(6I(or
cqualioll
(_1
c_lu_llo_ 161.
4.2 Tr_¢ blclho_
In lhl:li¢ou+itl¢
Ic_t,d/(l_rn_'_
tl++lw+:cn
noi_ ]cvclnor the C_lla_Iipipe willno_I
lh¢ _l_ll]c[
(I", 17_
Inn)) _nd IIl_l wllh II1_ Im_(flCr l_ mci_ulvd, to jhdl_lc
_l_l_lllldlll)ll, '_llC ,50ilht_
pl_l_tlfC I_YCI _ll_',i|ll_jlll_
poJnl I_ fi_¢_ .I _ _lv_rl pO_ili_n h0m Ih¢ ¢_ll_ltl_l _y_l_'m ol_l]¢l,
+_ p_IC lone, whll_ noil¢ alldc_h.lil_l llt_l_C l'lum [h(_ Ych_t_I¢ Ill_ I_I¢_[CL[
IIII _OHl_d _C_tI[CCI, Alli_
lnvc_tl_llon
1_ p_xZ_im_ lnl_l.dil_ Ill© cv,d.alit_n (WClllhlJniz) mclhod fur Ih_ _(mZliC .lIcr,_.tl_+ndltlln_
dm;_¢lcmll¢=.
4,3 T_I
4.3,1
Resullz
rm0Tnfl©'fZ+lland
Ilamt_oh_T¢ll
Tho nco_stl¢ lllcnil_lJOl_.dl_l_m+¢ cll+tl_l¢1111Ju_ (l[ 111_ 113i¢)£I_v+: b_fld 11o11©,l+lin_Lwhile nolle +if
noJ_oloslfc¢, m_l_llCa w_ll Wilh the chzf_cl_rizli¢I
of _ pzlt_ lone .i_ Io apptox, _OtJJl¢+ whcrz ¢oltlp_lCd
fll,
<
i
2
Complllsotl
of Ih¢ m¢_¢td
pnd lh{
¢i_lltlCd mli{/l¢l_ II1¢1_1111111nl
_'_1,
97
4+3+2 "|+llc r+l+ttJ¢Jn+h+l+belwc¢ll
(+'al¢Id+tcd V,hlr+ ,llltl P,Juasuxcd
V_hle_+
'|'II¢ +'chtii[]11_llip ilt:IWC©fl t:_llcUl_t_d v,_hJel _11(I l]It?;l_tlrL+_l
VJI_J_I OI+ Ihc rtlrl(tJtll_111Ji _'l¢inulll_+ _il{lWS
lllnlo_l s31JJ[;l_;Lt}Jyapll©u_tiJt1_£1ion. (+t_ifli)lll;lilOl_ oi ¸ lhL:©xl]Jlt_JuJL_irl4itL'_tJll,JlIt:t.
' i)'il_ I_ +'XClIII}iIIIL'LI
iii
l:ll]. 2 nZ +I¢Oll_t_ill+ItlOJ1
Of"IiL_' (LLnI1aJIIClII;LIcl¢It;crli'_
T_Ii_ sholvl |ii=I =i_o Ift lil_: t'omtlitl©Li, IllOLJ¢i_. ©u_'f.illon
itl¢;Itl=tiOlt ©hJi+,l¢i©fL)ll¢_ is po_it11L+.
4,3._
Char_trri_li_
(I]
of` l?_intialncni_l
i'+ Cx_¢li©J11 ;il1_t th41 _'llllliJIJ_)ll LI[ L11c
l_]_ii1cni_
l++xp_i1_JoJz_?i+mhur lyl)c
]_tom ¢_IculltJon
of" ¢_p_nlJon (4), lhe prnctlcul
l©nd¢_y in ihe cxp_lilol_ ©h_int)cr lyp¢ is _z folJows,
.
iiS llnkL
al_proxim_i¢
_inkt..
cqtJmtlon
IO cil_l_ a Li_lit,llve
........................
c+)
wh+lo
5: ._¢+llon¢l +lid or tli© cavily
_: 5cc(lon_lat©hi uf"lh_ iedcl _n(t o.tlctpipes
In Conli,sl,
, q.alilallv_
l©nd¢ll©y Jr+pnt_mt©tcr t+atlnlloi_
follow_, nnd the tyl+l_+l ¢_an)plcz arc _howlt in l:il_. 3.
D (cmylty ¢IiAinCl¢l'):
.L (c,vlty JCnEIh):
Lt+(laH pi._¢ Icn_lh);
•r.l, (llll©gl_on pll+C):
](cmo_lor
+_tu,l
Hlodcl_ Iz l;ivcn a_
Th¢ m_xhI1t_m _llcriu+llolt Jl plopolll+Jnal
Io 20 h+g+{S/_),
The nlmzL>ct of p_I+JnGfl¢+lilrll¢iC_ IIICtC.lrl p+ /. II IcHsth¢,+d.
It lh0w_ the ,_In¢ Icntt+t]cy ,t+ vatl,tlon
of`L
"l'l_c +:ll+lr+4cl_[iili¢l of` thc rc+_n,_n¢o type +:an bc awp¢i'illll)ol©d (]rl I|io3¢
o( lhc ¢_p,n_lon
(2)
u_inG lhe
lypc when l._a n+l L,_ nzc l_ll_lhc.++t.
fyp+
Wh¢¢0 IhQ Yoltlm¢_o_ the _¢son_n¢c ©hnnlb©r J_/¢l+r©z¢lll¢_l by V end II1¢ al¢_ o[ I|l_ ¢¢lorl,zR¢cIH)lc
by $@, resonant f`l¢qll©ncy (/i) of II1_ lc,onalor lypc _ ¢ly©rl al f"oJlOWl.
._ ._;_,.
Y_ri_ll_n_
Jn FJI. 4.
of lhc par_m+l¢l_
wltll
L_ (¢l_l_p |¢nllh):
Le.(rc_opant
hol_ I©nl|h):
'rho ism© Icndcn_y _| in Ih_ ¢,_p+_nslonly_
whg_ D I/_p i; In_++fa_¢l IO Homo _xl©nl+"
Ho Jn_l._n_
numh¢¢ of ¢©_on_nl.hol_a):
JP©rfnrlle_-pIpnl]_l
dl_p©Paion lypn
Tlthl ()'pal_n_.lh0/am<s tendency
_
' _ i_} ,
cxsrnpl©i_ shown
/1d¢_:_;¢1¢1 with ill |_lcr©RP(_
I)_ Lt bRI RII¢,_JI_IQ_ _o¢| fl¢)l
I_ (po+lllon):
(})
lhc;© Z+aclora arm l_Ivcn below, _nlt lh+ typical
/i dccf¢_lcl vtiih in Jn©r©al_ of"I* ifL Jn¢_d_)¢i, Ind I|}g
n.mhcr of pa_t _¢n,_;n¢ics which _l©pcndl Lll+Oll/ l_ho
Jnc_ci_¢ai
_/, (ires©nanI hol© dl_mCl¢¢_:
_(l_
(+:_,,,_ ,p,_,n......(01
Is Ihown _aaDp
[_ ¢h_ni¢_ by +_.fohfz
_s n Iflc_©A_¢l. _n_l wh¢n it i [l_rthc
/nc.'©_¢d. the igndcncy b¢¢Om©l ¢]o_ I0 lh¢ ©xpin_lon lyp©
(_._ I_/a, 4),
(Multl.holca lyp©)
as |he¢xplnllorl
lypq wllh 1©_p©¢¢l© lh_ _lcotllllc ©hmrP_;tcti_li©l+
98,
,_, +_j_t+
_.rr:.
•;
_ M" ;,
, ....
• _,
r ¸ _ _,.
d
_l,
c
_.m ,_t .r ,,. + m ,:,1_,
}
......
"tl
,, .'%-
*
:i:i::::4J ;- _
....
iOI
((_
a_
i_"
I0
lJarld holt©
__jr
<
_Jlh 4
I_[(cC|
U| [l_llllblr
ol + r_on_n!
] I
hulca
.L
I:l¢_lUCn_y
_
,o[I.M
I I/I
o+" wilhomt
Th0
_hara¢lc+'_lllCl
chala_lcfi_lJc_,
4.3.4
_otl/1,_
Ihcr¢
Ch,tJ¢lcfhlJcs
Tha
;©pl, l+_lor:
pl:
icoulllc
_,'om
Ih_
iN v_+'lat_nn
ab_ol_lcly
+
i+ltun
+*ltov©,
Ih_
of H.
ffl,:rJ
I¢md_m_rll_l
Ih+ll
_llCn_lllliqn
of
k.l
-
I_l...]
I
Allcnllllh)l_
vrhl¢l¢l
the a+o_li¢
clcrncnl|
wcro
Ih¢ pclfOlalCd.lflll_
virlm,_
ul
dmraclcfl_tl¢_
mcn[llmcd
abow.
II;1_ di_p_r_lOrl
lyp¢
I¢II
(Ico
I:il.
S_ll+_
nlklJNcrl
i'_r
1 ].
Ih_
Imnd
Jz I_rGcr (_.n
lloJ_
Ih¢ ¢_lp_rl-
fo_ Vch£¢_
nllcnu_lion.ftc+lucnc),
fr©qt+r no)" I_ dl_a+lvanl_l_o_JI.
_u¢h
o(
Hn ml{c¢lillon
,Q_i_l_ _1 |l_lcd
is a |_ndcncy
""""_
l_r_l.cnly (.l}
I_Jl, _
_1e in_
II
I
T
•<
L_
(tl_l
d -_4_-_ --I--_/"
_lll{
-
ch_l_clcli_lJ_
,:har+_:l¢lr)_ll¢l
Ih_l
_LI| Ih_ dllnptni+
I+¢O1_1(1¢ _l|lcnll_|lml
of
el'feel
4h_© Io
_ p_OlOlyI+©
I_1¢ mllm¢i"
Ihowjn_
*)f Ih© cxh_._l
Ihl_ Jrlilllcrl¢©
b© w_lahcd.
99
rm_fftcr
il
ce.lt_ln¢
d¢_¢1110
_y_lcm
£n¢lu,Jcs
<)f Ih¢ ¢_hllllsl
ills
_hown
in
|_Jl. _. ]1 It
A| _ p;irlIcUltlr
_ompli_alcLI
|ll_llnl,
f_clorl
i<J JL cRrlnol
i
5. DIIAFT
5.1
NOISE
TEST
(FLOW
GENEIIATED
NOISE
TEST|
T¢_I P.l_thf_d
A tuIJry hhlwcr I_ ,+*ud .i.. g dl;ifl _+¢)tlfcl+'+
_fl¢[ _l¢.Ltl)' +ill ctlfl¢llt i_ $11JlPJi
_d I u3lilt ¢'_h_ll_l _$1_il_ 1o
lit' Iv',tL'd vi:l Ih_.
_ ",ilL'll¢_'r. "I'll IITC,I_IIIc dt.llt J1¢115_'+
dll +HtCdll)l¢ [)U_ I$ II_t'd= d IITi_'l_ltlil_jtlk' I_ ilt_l+l_iCd.11
gjl Illl]_il_ LII '1_"= ,md ,_ IIc)_llL]ll ttl _Lj _'1il /'lt)ltl I_lc CxlI,JLI_I II*)_l =jltd
¢_f;lhl;tliLlll =l.llLd.lld. 111¢ I¢_1 _y_d¢lll hhlck dJ;¢L_r+lnl
I_ _lhlWll ill _:Jtl. (J.
_l _ll_l_ll_l
_11_1C
i'. ll',¢d luI
Ih¢
5.2 l+c_l ]to=oil=
Y, ht:n _tcady ail ll_w J_ _¢i=I It) tILe exhaust
syslcm
l]ow_r ol dr;Lit itoiS_ {xllich will I>_ prt_hLtcd
_'roln IhC c_II,3LI_t Poll _itlt nlll)fOx(llhll¢ h) I]ow vck)*:ily at, [ulh)w_/lUll1 d_lla 0[ I)'11¢_ol llllll+l]c[ _ILOwlL
I. I:_lJ. 7.
Wllh _+'_ _0 l.tls.I) l)' L _ II"t )1
Wllh _O._._'< IOU Jn/s.PIVL= (I.=)_
Wilh I+) I l)O fill _++I
_H".t._ (1,2 j4 _
_.2.1
Fcalt£rc_of
(I)
Exp_n=lgn lypc
(m)
(b)
((:)
F,ndantenl=l
l!lc.lltClll$
|)lafl I1¢1i_1¢v¢1I+ I O Io 20 dllh. hilthcr th._n Ihal ol+Ih¢ _lrall_]ll pill¢.
If ;I £ap t)( the lr_l)t£l/(]lllllLil ilt_,:tllt_. IIIIlUS J_r¢d.ccd+ Wlli$l]illL; ¢1o_¢ Io Ihc sl)C¢lfklln o_ a
PI£Ic hill¢ I_'lld_ Io I)l: Plcl_lll¢¢d I=¢c I:i1! 8l
Wll¢ll Ihc o==ll_l ill_t:llklH I)ill_ i5 I¢lil_thcilCd. draft ;Iol_c lncl¢_¢_ |_cc Fjt;, _),
R_I_I_ ll¥1_, Lwlye_will
'_;¢n£¢
bl ....
'_
.11.,, n,Cl_;lI_ _
r_¢ll, HI_I.oI_!=_n_ l°nt
I_lJ¢l
l+++kl,+¢=+.le
pl¢', _
_.+_______
(_+tov_l+l
J_J_.6 J_xpcrlm¢lll_l I&_'otll [or [lc_w _Cll_[llcd
Iixli.ult
,,l_e
d+_¢t
IIO
IlO
+
_
Im"KlCr
'
I_l/++_'
.h_
Fill. ? Flow t=¢n¢lalcd ,o1_¢ I_nc| Ilia|It+" tallo_*l
iI111I'_ ¢[I
100:
,,........
,+
4_._,++
._+..
li
ii
_I;:
',+'
_t
\.1,+
Now II1¢ (_+l, m,*l
FII,
II
P+llccl
iJI Ihl
Illl
ol
IllmpIllflolhlv,
Ioi¢1 inll
Ollllfl
[Flow IIII
¢lliin+
i_11¢1t1¢1111o11¢
I'11, II
ll¢lhicllonllf[lowicn¢lll¢illiulllhyhufn
I i+ll _ ¢11cnllllli
7I +
IO
f
,I
_l"lilil
"
JFI,,,
FIo.
pip'
""'
Dick pl¢lllltl
,,nii,lld
llO
._
lllllll
+i].Zi_+|
_
J+_'_+_"
*# *
,,lih,
ill---IX+
I_
I_li<lili+',¢Y
Ill
II15
i
i
i
,_
"+;_,i
i¢ I ti lif I_lp;i riiio n
¢_mkl
I)+lil
Ill,
I
%.
I0
_higli
ill
flow
b# Ill
II_i_
fill
._
_<
:
"" '_"""
_rll,Ttn"
(mmlll)
ii,
Ilp,ii,l,m
I,p.
i
'"i
•
_+j
• '" Elf©el
(_
l'l_iw llile
jJ
Im I,'_+_)
i
ik
it'
I:lliqli¢n¢Y(Ill)
If+pc illilillon
llhl¢lll
:_l
II } Splflll
of llulll+llrllil
I)+pl Wllh Icplrlll_l
ll+nilllid
nlil_i
ip¢¢llll
i01
{mll_i_l
pipe
l+| llll
Illillllcf
lot
(2)
(3)
_.2.2
I{_o11:Ja1¢¢CyJ_
(_)
_YIL_IIJl[ll¢_ h,_virltl _i_li_JIn_lc_ ill I_
til,lfl L0 ¢11JLI
,_f¢ [I]4_¢LI JIt Iw_ or (h1¢¢ _olv_ Jii JliJl_
(t))
_YJi¢13all oil_n_llL_ _JL,_lll¢l
_f ¢ _¢[_¢L1__0 Illlli, ¢_I_rllc
_ _l'_L_rl_!_$I_ _)_il1¢¢_1
J*_Horat _l-Ifilt_ ['._ di_l_¢_i_)rl I_p¢
_lll_liOll
(]i_l)ra[t Hoi_e
IL Jx _o11_i_1¢r¢([Ih,lt _lrJ|( JLO[_Ci5 _lf_JLIc_d _lJCto _ll_.lt rJ_to[_ a_ ¥1)rlcx, _(lll(Jf¢lioll. fiJ¢llL_il JILL[
i_ll_llall¢¢ _JL¢ll liJ_ll'_L_¢¢_l_JL,_I_I _JSJ|_W i)a_lc_ IJlrLJIJ_Lh
Ih_ rl]lL/IL_r. It_ _ll¢¢lltJJI1 I_ IilCd_llLiiiJt_d Ii_¸
_a a r¢_h_¢l_orl rllc,_n:_.JI _ H1111ort_llL
(ir_[ Io _]_l 4 rllLJ[/]_r JL,Ivirl}_low d_t
Ii_rd.Lo.wh_L)c cl_mcJit in Ih¢ huld:_rz_¢rlt,_l ¢lcrll¢l_t_ _ a very irl[l_Jlti_l
COll_j)olLciiI. LIL_ ¢_1JJ¢
i5 if(Lp_lhUIt. [11(_rLJ_to _r_¢llt Li_¢cd_ _ofn I!_ltlr3_ t(}o
JCl _lrcall_, tile ¢_1_ _l lllod_ IL(_IJl._lt_l_cLL
(re[cried hJ a_ wiLh l() which _r_tly
nol'_¢,
FiB, I1 _how_ IJlc ¢(i'¢¢t o|'ltc)is_ rcductior_ irL Ihc cxp_n_ion lype, where Ilic
20 dllA. Wilful Ihi_ i_ allpJicd to the ii_LJ_l_¢rfor Ih¢ _hJ¢]¢. thc ¢[_c_t Hio_v.
¢lll¢¢J_ly
_h¢ iI_lrofJiCd-ilijl_
lloia¢ Icwl, _pc¢i,illy
i_rL o[ th_ Jli_crll_l
ctc]_¢ tLI I1_¢¢OlU Of t]l_
[¢LJLI_C_I'iL_w ltcllcr,_l_i
iic)_c i_ rc_Juc_'dI0 tu
I_1 I:IL;, l_ J_ obtJmCd
_Ls _li_lltl_ioil t)'l]¢ wLth Lh¢_j),l_,_tor i_ Jr1LIL_¢_IJLJll,and _( J'_al_lllL),_, .1
C_[cct uf 40% t_dl_¢l[oil ilt b,l¢_ ii_c_LlfC _ _¢_liCV_LIhy _¢l_llll_ ,t ll_'fforalil)ll
I.H¢ Irorrl I._ Io ._O.
fold_ dr1many _tt I_1_(lliKiliJl (1r_c4_1
t_lC protuL_J_ IIILLII]cr _lr I_1¢v_'JiJ¢l_.
_);]lp_fi;_Jn or _(t_ltu;itiul_, d_[t noil_ I_vc[ ailL_I_,lck IH_Ltr¢ tla_cLJon the _[]'_ii_jritiliil_ j_ _hOWll JJI
'_'_bl_ 2,
6. TESTS OF RADIATED
NOI._E FfIOM EXHAUST
_;Y_TEM
6,1 _¢3l I_l¢lh(_ll
'|'|to I_hcm_tJ¢ tc_t _y,_ttlTI bhlck di._Bf_lll J_showll in [:J6. 15,
|n Ih[I t¢_(_ I|1¢ cAI1_0_t 3y$(tlll (in IIIC vthiclc i_ vibl_lt_l orl a tln_ [o illVt_lJl]_[c [hc VJbF;lli(llZ It_llnll_C
[:ll_r_¢i_lJ_l_c_, ilrld hld_lt ¢¢1I1(}i_(: II(1111(ll_ lilac W_IIIi_ lylll¢_til _ 111_:_1_11lC¢1
Oil II _:J¢)_C
J¢l_*llJ[lll ill_Jllly Io
Jllvl:f*(J_4(cI_¢ I:UIICl41iC_Iib¢lWtL'_) vibf,t$iDli ,1fill ZltlhC, I:*Jr (h_it (_12(111,ltOfllldJ _ilI_'W_¥C vZllfali(trl _111_1
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METHOD
MEASURING
AND APPARA'I_JS
MUFFLER
PERFORMANCE
Peter Chen_
'
STEMC0
MFC_.
CO.
Lon_{vlew_
Te.x_
109
i
The measured quantity
in our test facility is not the trassm_sslon
loss nor insertion
loss, but the pups exhaust noise undep conditlons
simulating
those specified by state and federal truck noise laws.
The tool to evaluate the pure e×haust noise is a bench test conducted
at a test facility where total isolation of all othez, noise sources
is feasible.
The cross section of exhaust noise test lab is sholvn
in Fi_. i,
The installation
featspe,'_ an underground
structure
to mount test
engines
and watep brake dynalnometers.
']'hisstructure
set,Yes to
isolate the mechanical
and all, intake noises fpom the exhaust noise.
All the exhaust fDom the test engine is piped directly
above the
ground to the muffler.
The exhaust pipes ape positioned
in a manner
au clouu to that _ound on the vehicle as possible.
The site Was chosen fop it's compliance
with SAg specification
fop
stationaz_y and drive-by test.
That is, it is an open space test
site with no neat'by rcflcotin 8 surfaces.
Typical ambient sound
level is below 50 dB(A), well below the measured levels.
The height
of micl_ophone and sepapation between miepophone
and mufflex, is
specified
as IIft. and 50 ft. respectively,
so that the measul_ed
exhaust noise level would be about the same as that fro;n a moving
truck undergoing
a dplvc-by
test pep SAg J-366b procudupe,
Before the testing modes
thru Fig. 2 the drive-by
are introduced,
let U:; review
test pep SAE 386b.
bpiefly
The vehicle
under test approaches
point A with 2/3 of the rated
engine rpm and begins acceleration
at point A under wide open trottle
so t'hat the rated cn_ine rpm can bc peached somewhere
within the end
zon_.
To slmulatu
ducted •
(A)
,
(B)
(C)
the
test
conditions,
Steady state mode
- rated engine speed and full
throe
test modes
tide con-
iodd
Vaplng speed
full load mode
- engine, speed slowly varied fr0m rated
speed at wide op_n throttle
tlpeed to
2/3 of _ated
Acceleration
mod_ - accelerate
the engine from low idle to
governed
_,Ipe¢'.d
%_ntll thu engine speed otabili;:us and return to
low idle by rapldly opening and closing the thpottle
usdeP no
load eondltioNo,
Modes
(A) and
simulates
the
i
vehicle
(B) clearly have the drlve-by, ts,'Jtin mind.
statlonary
vehicle noise test.
ii0
l'lode
(C)
(2)
The
"sound
recorded
modes,
level ratins"
in Stemeo a/termarket
catalog
is the highest
exhaust
sound level measured
in above mentioned
tcs_
j]ur,c
The "sound level mating" defined above
many cases.
To illustrate
this point,
listed below will be e×amined.
EI_n/_ins
Spccd(_pm)
Muffler
may be too eonsepvative
in
thmec hypothetical
cases
Sound Level (dBA)
A
liulflcr.B
"Hurl!let C
2100(_ated)
71
71
71
1900
73
73
73
1400
75
70
77
In %he ease of Mufflc_ A, the peak value of 75 dBA at lifO0 rpm (2/3
of rated rpm) may not be a fasted in the drive-by
test.
The distance
betwe¢_n "l:he microphone
and point A is 70,7 ft. instead of 50 fr, and
usually other _oise eourcds do not peak ulrtil at higher rpm's.
Muffler
A and B may yield identical
total vehicle noise pep dl,ivc.-by
'test. On thc_ other hand, the peak level at 1400 rpsl in Muffler C'o
case may indeed affec_ t|le total vehicle noise in drlve-by
test.
A
peak valu_ at 1900 Ppm op 2000 ppm ;nay also be important bccau:le the
vehlel_J would be close to point B in Fiz. 2 and bc right in fron'_ of
1:ha microphone.
It is therefore difficult to use one dl_A level to correlate
bench
%_s% _esul_
and d_ive-by test Pesul%s without
being either
too liberal
or %00 conservative.
BUt to ._ largo extent, muffler de'JiB,
nero can
usually
use,the
bnl*eh test result_J and judF,e how the mufflc_ will
perform
in a drive-by
test.
.=
n
lli
i
i
L
C.
:i
STEMCO
EXHAUST NOISE
TEST FACILITY
t
50
t_
£1g.,
II
l,
12
;,::,.
, .e:
,
1
A
I
B
•"
C
'v'i/iiiiilHiilJ_
END ZONE
50'
_ICROPHONE
Fi_. 2
Schematic Diagram of Dpivm-liy Tent P_p SAi:-36f}b
_ _:
i
I
?
113
•
: C::.,
i
"OPTIMUMDESIGNOF MUFFLERS
by
D. Baxe_ A. Daz^_andA. Se|re_
*_
Universityof W1sconsln
Madison, Wisconsin
* Assls_antProfessor,Departmen&of EngfneerJng.&
Applied Sc|ence,U_Ext.
_
ResearchAssociate,MechanicalEnglneertngDepartment
**_ Professorof MechanlcalEnglneerln9
'
':Z
II}
Optimum Design of Mufflers
by
D. Baxa, A. Baz and A. Soirog
University of Nisoonsln
Madison, Wisconsin
Abstract
This paper describes
a computerbased-designprocedurefor selectingthe
optimumconfiguratlon
of automotivereactivemufflersand acousticsilencers.
The procedureutilizesa specially developedschemethat predictsthe press,re
histories,and accordinglytileaccompaniedattenuationor amplification
of the
noise level, resultingfrom the sinlultaneous
reflectionand transmissionof sound
waves propagatingthroughvariableimpedanceexhaustrobes.
The developedprocedur:e
is generalin nature and can be used for synUmsizIng the optimal conffgoration
of mufflersfor any given operatingparametersand
designobJectlvos.
Severalexamplesare glven to illustratethe optimummufflerconfigurations
necessaryto minimizethe transmission
of noise levelat differentworkingcondltlons. The examplesdnmonstratethe potentialof the developedprocedures.
Thf;describedcomputeraided designapproachcon be readilyapplied for dlfferentpatternsof exhaustpress_ire
waves,nlufflers
wlth excessivetemperature
gradientsand wall frictionallossesas well as any other operatingconditions
and design objectives.
116
,4-
Introduction
The contlnuouslyincreasingdemand for high performanceIoternalcombustion
engineshas forcedthe automotiveengineersto raise considerablythe cycle pressures and the enginespeed. Suctlmodificationshove contributedconsiderablyto
tileincreaseof tileextlaust
noiselevel to tileextentthat It becamea major
environiiIentalpollution problem.
Consequently, efforts #lavebeen exerted to de-
velop severalforms of exhaustsilencingsystemsin order to meet the severerequirementsof the noise pollutionstatotorylimitsHithoutreduciogthe engine
performance. Realizingthe hllportonce
of developingbettermufflerstileautomotive
industryin the USA is expectedto spend $16.to$100, per car to meet the 1978
noise pollutionstandards[I]*. Such figuresw111 deflnltelybe hlgherInyears
to come to meet tilegrowingneed for cars Hith betterhandling,i.e.with low
centerof gravity,and thereforewith very limitedspace for the exhaustsystems.
14Iththe e[_Isslon
controloomponents,the mufflerdesignerHill, thns,be onder
pressuresto developeven n_re efficientand compactsilencingsystems.
The (Ievelopment
of automotivejilufflers
has generallyreliedon empirical
sklllsguidedby past-experience
and sln)pleacousticprinciples. Some design
guidescan be also fonnd for simplemL_ffler
cnnfignratlons
as givenby Magrab [2].
Only in tilerecentsyears has the developmentof a_itomotive
exhaustsystems taken
a more systematicand rationalapproachas can be seen in reference[2] to [6].
These effortshave presenteddlfferen: simulationtechniquesthat utilizethe
wave propagationtheoryto predictthe dynamicperformanceof reactivem_fflers.
* fIImlbers
betweenbracketsrefer to referencesat end of p(iper
i
117
The validityof the developedmuffler simulationmodelshas generallybeen tested
eitherexperimentally
or againstelose-fomntheoretJcal
fomnulasthat are developed
for simple muffler configurations.
Coil_lonalso omong these studies Is tilefact
th/_tall havebeen used only to analyze the performanceof reactivemufflersat
dlfferentoperatingconditionsratherthan to devisemeans for selectingthe optlmom mufflerthat is best suitedfor a particularapplication. Few attempts
[7,8]have been made to optlm]zethe performanceof mufflersbut theywere based
on exhaustive-experimental
'searchfor the geometricalparametersor theproperties
of the liningmaterialsfor a mufflerof a particularconfiguration.
The purposeof thls study Is to developa compl|ter-based
designproced.re
to synthesizethe optimalconfigurationof any reacClvemuffler for any given
E
operatln
9 conditionsand designobjectives. The analyLlcalprocedure|s based
on a computerlxedone-dlmenslonal
wave propagationtechniquedevelopedby Baxa
and Selre9 [3], Thls techniqueIs used to monitorcentlnuoL|sly
the reflectlon
and transmission
of pressurewaves as bhey propagatethroughvariable]mpedance
exhausbtiibes.Consequently,the pressure-tlmehisLoryat any locationinside the
muffler can
be determinedtogetherwith the accompanieddegreeof attenuaCion
of the noise level,
This optimaldeslgn approachof mufflersw111 elimioatethe exhauCtivetrialand
error searchfor the bestmuff1_r ft any given situationend thereforereduce
the cost of developmentof the car_s exhaustsilencingsystem.
The optimization procedure used ie this
study Is an adapted version of
that developed by I_allaceand Seireg [9] to optimize tileshape of prismatic
bars when subjected to lorlg|tudlna]iIilpact.
_Com)jlutatlonal
Schemlle
for the Analysis of iVaveprop._!latlon
in M[_fflerswlth
St_p Chanues Ill .II!npedarlce
Tileclassical tileoryof one-dlmensional wave propagation enab]es us to predlct the pressure P at any location X
and at time
t
by relating those para-
meters by the following eq :
.B2P.
DX2
l
C2
D2P
Dt2
(I)
where C is the speed of propagation.
This theory ass_nes
that there are small changes In the Instantaneous density
aod consequen_.|ytlleinstantaneous value is approximately equa| to tileaverage
density PO' that tilewave propagation is frlctlonless, the medium is homogeneous,
and the sound levels are belo_ l]O dB re 0.0002 mlcrobar,
Tillsequation has long bP.enthe hasls far the analysls of one-dimensional
transmission
of waves and their reflections where changes in impedance occur,
The evaluat|on
of pressnre variations in t_bes can become more difficult as the
nu_ber of impedance cilangesincreases, llowever,wltilappropriate schemes, such
as that developed by Ba_a and So|re9 [3], these problems can be conveniently
and econom|cally analyzed,
119
l,
The follotving are some of the basic assumptions made in the developed
nluffler
analysts program:
(I) Pulse lenc]th is longcompared_ith
the tube diameter.
(2) The sourcemoves tile
entirecross-sectlon
wlth the same
particle velocity.
(3} PressarefluctuationlevelsremainIn the linearelasticregion.
The first assumptionimpliesthat the wave would have a constantspeed
of propagation,which is detemined by:
o
•
OO
where y - 1.4'.PO • mean pressure;PO " mean density. The secondassumption
indicatesthat thewavesmove as planewaves throu(Jh
the tube. Finally,the
third assumptionsuggeststhat thewaves and theirreflectedand transmitted
componentscan be combinedby superposlCion.
The time necessaryfor a disturbanceto propagatethrougha tube segment
of lengthL can be calculatedfro_
tp ,, L/c
(3)
in a complextubeoomprlsedof _n.v differentsegments(FigureI), a
propagationtime is determinedfor each segment length. By co_nparlng
propagation times,a ratioof nombersKI, K2,...,Kn Is determinedfrom the
fol lowing expression:
- '
t. -
.
KI
t
.
...
K2
.
(tpl
n
Kn
120
(4)
The s_gnfflcance
of these tnteCjers is thor It takes a wave K1 units of time
(where one unit is tu) to travel
travel
the length of the ftrst
the length of the second seglnent, etc.
oremultlples
Because tile propagat|on
of the unlt of tlJne, t u, the 4nltia]
transmitted waves will
reach tbe interface
segment, K2 units
wave and all
to
times
reflected
and
at times whlcll are some multiple
of
Ill'
Every section of the tube has an acoustical
thelnean density (po), the velocity
' (S) of the pipe.
The relatlonship
impedance which depends upon
of propagation (c),
and the cross-section
is as follows:
Z _
PoC
_-
(5)
Doc is often referredto as the cbnracterlstic
{mpedanceof tilemedium.
By consideringthe pressureand velocityequalitiesab tileinterfaceof
a wavegoing from tube I tQ tube 2, it can be shown[iO] that the transmlssion
and reflectlon.ofthe velocl.tles
are as follows:
UR •
Z2 - ZI
Ui
(_)
Z2 ÷ Z1
2Z_
S2
Z2 ÷ Z1
S1
Ur "
Uz
(7)
! ',
whereUI, UR and [IT are incident,reflected,and transmittedvolumeveloclties,
respectively;
ZI and ZZ are the impedancesof tiletwo tubes. Since pressure
.!
.
and volumevelocity are related by:
P _ u POe/S
121
(_)
equations(6)and (7)become:
Z2 - Zl
PR "
PI
(9)
Pl
(10)
Z2 + Z1
2Z 2
PT "
Zz + Zl
_ben the densitya(Idvelocityare constant,
1
M
1
- S2
p_ =
(_2 ._ SI'PII
)
"
(slsl
+ ....
s2)PI
cB Pl
(11)
cTP[
(12)
t_herecR Isthe refIectloncoefficient.
2S 1
'PT "
(I
+ I
)PI -
(S1 ,t-
)PI "
WherecT is the transmissioncnefflclent.
Consequently,
when the magnitudeof the Incidentwave and the physical
propertiesof the gas In the tubes are known, the transmlt_edand reflected
portlon_of the wave can be determlnedfrom equations(11) and (12),
In order to analyzea generalwave being emitted fromthe so.rce,the
physlca)propertiesand tntttal
conditions
of the sour¢_and of every segment
of the tube _ust be known. These propertlesshouldInch|dethe impedance,
speed oF wave propagatlon,area, and length. In the case of a homogeneous
gas the reflectionand transmissioncoefficientscan be reducedto a function
of area only. The ratio of the propagationtimesm_st also be known.The Initial
122
%
":,i,
li_,
.i,
..
conditionof tiletube is consideredto be that of"no pressurewaves inside.
Tllerofore,
it
can be seen that knowing tile parameters of area (Si),
lengtll
(LI), staticpressureof the gas (nO), staticdensityof the gas (po), and
the ratioof tilespecificheat of the gas at constantpressureto that at constunt
volume (y),
one can determine tile pressure history
inside
tile tube.
Tile
wave propagationspeed can thenbe determinedfrom tilerelationship
c .
0 or
"--
c _ v'Y-_,where r is a constantdependenton tileparticulargasand T is the
temperatureof thegas in degreesabsoInte, To detennlnethe impedanceof each
tube segment,tiledensity (nO), the speedof wave propagation(c),and the area
of each segn_..nt
(Si) are substitutedin tileequaLlonZ - Doc. The propagation
times Are determfnedfrom the segmentlengthsand thewave propagationspeed
as tp " l.lc.
A'ratloof Integersis foundfrom thlsarray of propagationtimes,either
by vlsu_linspectionor with the help of a computerprogram. Sinceit is assumed
that each tube segmentcontainsthe same gas at the same pressureand temperature,
the speedof wave propagationreF_Insconstantand the ratioof propagationtimes
will be thesame as the ratio of segmentlengths.
OnceAll the physicalprcpertiesand initialconditionsare knc_vn,
the
pressure-timehistorycan De detemined as follows. After each unit of time,
each interfaceis checkedAnd the reflectedand transmittedportionsof the
waves are calculated IJyusing equations (l)) and (12). All of the waves travelling in the same directionfroman Interfaceare sni(_ed.By knowingthe magnlrude of a|l the waves arrivingab and leavinga given interface,it Is posslbl_
123
i
i:
t,
to constructthe "pressure-tlnle"
historyat every interface. This procedureis
repeatedfor each unit of thno until a steady-stateconditionIs achieved.
The analysisschemeutllizesthis approachand can be used In one of t_Yo
modes. Flrst, the responseto a sinusoldalinput can be determinedand the
transmissionloss can be calculatedIn decibelsfor theentire system. In the
secondformat,a generalperiodicpressureInput can he read in and used to
calculatethe pressureresponsesof the system. This secondapproachIs particularly usefulin determiningthe effectof a tuned exl)aust
systemon the pressure
history.
The computerizedroutineIs developedto includeas many segmentsas can
convenientlyfit into the computer. Eachsegmentcorrespondsto a particular
portionof the muffler. It Is also possibleto set the sourceantitemination
impedanceIn order to Investigatethe effectof this variationon the system,
If the sourceor end Is completelyabsorptive,the areaschosenwould have the
same area as the connectingsegment. If the sourceor end Is completelyreflective, the area chosenwould be zero. A flow chart of the developedscheme is
shown in FIg. (2) to illustrateits differentfeatures.
Strate_ for DesIgnlngOptimumMufflers
The designof A stepp_d.configuration
reactivemuffler for ateenuatinnof
exhaustnoise levelsis formulatedas an optimalprogrammingproblem, The major
considerations
in this formulatlonare the identification
of the decisionparameters, the descriptionof the constralntsimposedon the design,theexplicit
statementof the objectiveand the developmentof a sultablesearchtachnlque
for Iocatin0the optlm_m designparameters.
124
i
1
_ _
:_,_Jf -!_-.,'
:i_
/.L
Muff]er
*¸ =
Parameters
For the _eneraI case of a segmented muffler,
Jected to general periodic
tea,perature,
it
pressure ivaves of kno_m amplit_lde, frequency and
then the system variables
a,
number of muffler
b.
Length 'Lt'and
c,
Source and termination
are: -
segments ,. n
area 'St'el
eachrm{ffler
system parameters is {2n + 2),
segment wbere t = 1, ....
,n
Impedances.
can therefore he seen that for the n segment
The remaining variables
as shorn In Fig. (1_, is sub-
m
nmffler
the total
nunlber of
Some of these parameters are specified
beforehand,
represent the decision parameters and have to be selected
within the constraintsimposedon them In such a way as to provide the highest
possibleperformance.
ExEI_cltstatementof MufflerdesignObJectIv!:s
An oxpIicitstatementof a merit criterionwhich accuratelydescribesthe
designer'sobjectiveconstitutesa very importantBatters|ncn tllIs
criteriongnides
the searchand determinesthe selectionof the optimumvalnesof the decision
par,
._,'s.
F..xamples
of the possible objectivecriterionfor thlsclass of problemsare: (a) Maximizationof the noise transmissionlossesat theenglno
operat|ngspeed.
(b) Maximization
of the noise transmlsslonlossesover a _Idm range
of enginespeeds,
(c} Ma_Imizatfonof tbe negat{vepressuresdevelopeddnrtn9the
suctionstrokewhen using a tuned muffler.
OtherdesignobJectlvescan be used to guide the selectionof the mufflerdesignparametersin order to meet the requirementsfor any particularsituation.
Search Method
The steepestascentmetilod
is utilizedto serachfor the optimumdesign
parameters
of mufflersin order to achievethe maximumattenuatlonof tilenoise
level,or an),other objective,associatedwith the incidentpressurewaves. Tile
optimization
methodguides tilesearchfor the optimumparametersalong tlledirectionof maxlmnmattenuation,or any otherobjective,by changingthe value
of each designparameterXi independently
by a small perturbationAXi and noting
theaccompaniedchangein the noise levelAU. The new value of tiledesignparameter
Is determinedfrom theold value
accordingto the following
Xlj÷ 1
Xij
relationship:
Xlj+1 - Xlj + I (AU/AXI)
i - I,....R
(13)
whereM is the numberof decisionparameters. _ is an optlmall:¢
selectedstep
slx'e
that controlsthe changesbetweenpointsJ and J÷1.
If no Improvomentocc_4rs,
the parameteris variedin the oppositedirection.
If this alsofails to producean improvementin the merit value,this parameter
is kept constantfor this step and the value of the other parametersis changed
In a slmilarway,
The detallsof the adoptedoptimization
schemeare shown in the flo_ chart
of Fig. (3) to indicatethe means Includedfor selectingthe maximumstep size
withoutviolatingthe constraintsand for avoidingthe terminationof the search
at regionswhere the attenuationlevel vanishes. Sucllfeaturesmake the use of
i
!
126
;
I
•
...
••_'__' ;_,_..? 'L¸,
.
the steepest ascent method very suitable
of the mufflers because it
for searching the complex design region
is extremely sensltve
to parameter changes.
Therefore,for re.qlons
where no sharp ridgesexist in the contoursof the
objectivecriterion,this algorithmis equivalentto a gradientsearch, But
for situationswhere a ridge existsin the designspace the MgorIUm_ is in effect
a univarlatesearch.
th__ertcal Examples
The optim_mldesign procedure is used to develop the optimum-muffler configuration
necessaryto maximizeti_e_ttennatlonof the noise level of a partlcular
pressurewave with a frequencyof 1000llzand flowingtl_rougi_
tilemufflersat
a temperatureof 70°F. The procedureis utilizedto illustratetileeffectof
changingthe numberof segmentsof themuffler on the degreeof optimumattenuation of tiletransmittednofse. 14ufflers
having a fixed lengthof 3 feet hut
wlth 3, 6, and 12 segmentsare considered to Illustratethe potentialof the
procedureIn optimizingm_ffler configuration.
In e11 the consideredexamplesthe design problem is form_Hatedas follows:Find the areas of the se.qments
SI
i , 2 --_ n-1
,P!pgut_
To maximizethetransmissionloss .. TL * 20 leglO _Poutput/
such that
db
Sl _, Slnput
SIN" Soutput
Smln _S! _Sma x
Li - l.fi
g]
i - I.....n
where each segmentlengthsti is equal to a given value
_l
I
(14)
f
127
Lf_
I,
In tileabove formulationthe mufflerdesignercanselect the desiredlimitson
tllearea and length of each muffler segment.
Consequently Sinput, Soutput ' Smin,
Smax and Lfl are fixed valuesspecifiedaccordingto thedesignerrequh'ements.
In the followingexanlples
these limitsare takenas follo_vs:
-
Sinput
= Soutput , 1
Smin/Sinput- O.l
Smax/Sinpu
t-
I0
Lfl/k
3/n
i
where k is the wave lengthof the incidentpressurewaves
!
FxamRll
e 1
i
I
i
Fig. (4) shows the resulCsfor a 3 segmentmuffler,as that shown In Fig.
{4-a). The optimization procedure wi&h m initial configuration will produce the
configurablonshown In flg. (4-a). Sucllan opUmal configuration
resultsIn a
noise transmissionloss of 10.3 dO as comparedto the 5.09dfilossproduced
by the configurationof Fig. (4-a), it Is interestingto note that thearea
of the middlesegment in the optimalcot|flgaratlon,
has Increasedto reach the
maximumallo_,ahle
Hml% set by eqn (15). This agreeswlth the co_on practice
of singleexpansionchambermufflerdiscussed,forexample, (2 and 3).
!
Example 2
This examplelllustratesthe effectof changingthe numberof segmentsof
the muffleron the noise attenuationuhileoperatingunder tilesame conditions
as in the previousexo,_plo.
Fig. (5-a) silowsthat starting_Ithtile6 segmentmufflerillustratedin
Fig. (5-a-l)then tileoptimalconfiguration
will be as shown in Fig. (5-a-ill,
and the noise transmissionlosseswill
be 9.6 dg which is a lessefficientde-
sign than thai:producedby the 3 segmentconfiguration
of Plg. (4-b).
hut If we start with the configuration
of Fig. (5-b-i)thenthe optimum
configurationillustratedin Fig. (5-b-ll)showsa considerableimprovement,
nearly24.3%, over the optlmom3 segmentmuffler. If we consider,however,the
muffler configoratlooof Fig. (5*c-i)as the initialstartingpoint for tile
optimizationrolltine,
then"theobtainedoptimumconfigurationof Fig. (5-c-ll)
yieldsa considerableImprnveme.tof 61.4%over the optlm;_m
3 segmentmuffler,
It can thereforebe seen that iBcreasingth,,nu,".'"_.r
,, :_,jments
of a muffIee
of a .giventotal length,is e_pectedto producea considerableincreasein noise
attenuation.
Also, it is interestingto notethat startln9with differentinitialconflguratlonsdoes ,ot producethe sameoptimumconfiguration.This is due to tlle
complexityof the designspace and emphasizes
the need for optimization
tools
for designingmufflersan(Jacousticsilencers.
129
r.
•
.__mm_,.m_._"zj3_,,;,_,._?..,'ii_.
:_v<.,:.::,:,,'C:_'I.?._L:j,_
_(C_',_
-_z
_''_:_''_"*_
........
_'_"_}_';_'_'_::_'_i_L_
Example3
Thisexaulple
shows the improvementIn noise attenuationresultlngfrom increasingthe nuu}ber
of segmentsof tilemufflerunder considerationto 12 segments.
Fig. (6-a) showsthe initialand theoptimizedconflguratlons
which result
in a noiseattenuationof 30.24 dD. Tillsis almost threetimesas much as that
Of the optimum3 segmentconfiguration.This optimal12 segmentshape has been
obtainedIn a singleiterationby the developedoptimizationroutine.
Fi9. (6-a-fi)shews anotheroptimalconfiguration
wldch Is a synwnetrlca]
arrangementof multl-connected
expansionchambers.
If _n considerthe initla]12 segmentconfiguration
of fig. (6-b-i)then the
rcsultin9optimalmufflerwill attenuatethe Incidentnoise levelby 32.34 dB
which is @.94% betterthan that producedby the configuration
of Fig. (6-a-il).
The paper hasdescribeda computer-based
designprocedurefor optimized
configurations
_ reactivemufflerswith step changesin _elr acousticimpedance
when subjectedto periodicpressurewaves. The existenceof multipleoptimum
conf|gurntions
isevidentby the dependenceof the finaldesignon the selection
of the numberof segmentsand the startln9point of thesearch. The cons|dared
examples illustrate
the potential of the developed computerized optimization
approachas e powerfultoolfor syntheslzin9
the optimalconfignratlons
of
reactivemnfflers.
i
130
_zJ
i:¸,
•: " hi:
;_i
I _:_'.
Although the optimization
In the considered examples is based on the
maximizationof the noise transmisslonlossesat one frequency,tiletechnique
can be readilyused to optimizetilemuffler designover a _YIderangeof frequenciesas Hell as optimizingtileexllaustplpes for Iml}roved
engineperfolunance,
The procedurecan a]so be app]Icableto situationsHhere factorssuchms
mean flow, frictional]osses,temperaturegradients,variablesource and
temlnation Impedancesshouldbe consideredin the designscheme.
i
'
131
'
i-
;
"
_'_._t_'•
References
l.
lleath, R.A., "Hhat's
Ahead in Control
the Automotive
Muffler
Field,"IL Proc_
Na--a"_ona-na--_[-Noi_e
and Vibration
Conference,
Chicago
June of
1974,
pp. 87.
2.
ffagral_ab_EE.,
"Environmental
T_J7_, pp. 215.
3.
_nd
__lers
4.
p_
P.O.A.L,,
"Mufflers
for Internal
Combcstlon Englnes,"
"Inter-N_Co-rTference,
Denmark, 1973, pp, 143.
Noise Control,"
J. Hi]ey and Sons, New York,
A. Snlre,j, "A Computer-based Procedure for tile Analysis of
ari'd ?uned Exhaust Systems," Prec. of NOISEXPO, 1977.
Prec.
of
.5, KarnopJ!, D., a. Reed, D, Mar__olis and II. Dwyer, "Design and Testing of
Ileact_Ivi_-i_T/Cfle-Ts?_,r--Proc.
of ln_r'-Nolse
Con_ence, Washington, D.C.,
1974, pl). 325.
6•
Okda, a,, "Performance of Reactive Mufflers and Calculation of Engine
l_xla_'llolse,"
Prec. of Inter-Nolse Conference, Sendal, 1975, DP. 655,
7,
Lykk_.,
"Design of Reflection Type Sllencers
ot_-Reael;Ive Acoustlc Filters,"
Prec. of inter-Nolse
1973, pp. 158.
D•
•
Ver_L,
Design Optlml.zatlon of Gas Turbine Sllencers,"
Noise Conference, Sendal, 1975, pp. 687.
9.
Wallace, O., and A, Selreg., "Optimum Design of.Prismatic Oars subjected to
_'-I_S-ME
Paper _o. 70-DE-G, Trans, of ASME,J. of
Engineering for Industry,
I0.
Klnsler= L.E._ and _A.R. FrL_, "Fcmdamentals of Acoustics,"
,')7"W-fTeTa'n'd--S_nc"TT",
New"York, 1962.
?
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BErlCIt
TEST AridA/IALOGSI_IULATIO_I
TZCHHQUES
ENGINE
HUFFLER
FOR
EVALUATIOf_
by
Cecil R Sparks
Director, Engineering Physics
Applied Physics D1vlslon
Southwest Research Institute
San Antonio, Texas
Presente{lto:
Surface Transportation ExhalJstSyst_n flolseSymposium
Sponsored by tileU. S. Envlro_ental Protection Agency
.
Chlcago, Illinois
October 11, 12, 13, 1977
ABSTRACT
The problem,
s associated_ith laboratoryevaluationof e{_glne
mufflersare
primarilythose of (I) deslgnln_a facility_,.hlch
v11llprovidea meaningful
measureof muffler noise reduction,and (P.)relatingthis physical(acoustic)
data to the action of themuffler _hen placedon a specifleen(J(neexhaustsystem. IRlilea _iId.e-band
siren can be designedto provldn a suitablenoise
speetru_and 5ource Impedance,perfon_anceof a{_ymufflermust ultiesately
depend on the exilaustpl'ping
configurationInto _altch it Is placed. Experimental work In the 1960'sat SwRI has _llounthat a bench test facilitycan provide
useful acousticdata If the ea$_dldat_
mufflersare being evatuatedfor a relatively narro_Y
range of engineapplications,and a loudnessevaluationtechnique
was evolvedwhlch could reliahly re]atedata fr_n the bench test facilityto
perfomance (soee reduction)on an engine.
In addition,electronicslmulat_ontechniqueshave been evolved_lerebv
the entireexhaust systc_i]
(mLiffler,
manifo)d,an(iplpJng)can be qL_ntltatlve]y evaluatedon an eleetrnnceustle
analog, Althoughdesignedprlneiplyfor
s_mulatlngpLilsat|on
fllters,thls analoghas been extensivelyused for slmulatlng the exhaust systemsof reciprocatingengines,and for the design of
muffler_specificallytailoredfor that engine,exhaustsystem,and range of
operatingconditions.
I
144
BERCII TEST AND ANALOG SIMULATION TECIIIIIQUESFOR
ENGINE IIUFFLER EVALUATION
BY
CECIL R. SPARKS
BACKGROUND
The problemsassociatedwith evolvinga bench test procedurefor evaluatln_ tileacousticperfornlance
of mufflerslie chiefly In tim fact that there's
no such thingas an inherentlygood muffler. Regardlessof mufflerdesign,
the NR affordedby anymuffler Is not a functionof the mufflerdesign alone,as
the rnuff_er
is merelyone port of a complexacousticpiping systmn. The "best"
muffler forone enginemay actuallyamplifynoise from another.
Re.log
a passiveacousticnetwork,a muffler'sperformance(arnpllfication
or attenuation)
dependsnot only upon its internaldesign but also upon.its
source and termlnatloaimpedance(i.e.,tileattachedpiping),upon the spectral
distributionand omplltudeof the enginenoise spectrum,flow rate, pressure
drop and, of course,acousticvelocity(temperatureand gas co_posltlon).
This Is not to say that somemufflerdesignsare not betterthan othersfor
a given _angeof conditions,or that an optlmmnmufflercannotbe designedfor
a specificsetof conditions(and assuminga specificset of constraintson size,
etc.), but as soon as englne operatingconditlonschange, or themuffler Is applled to a differentenglne,its performancecan suffermarkedly. Normally,muffler
design Is tailoredto cover the rangeof engineoperatingconditionsexpected,
and Is designedas an acousticlow pass filterwith a mlnim:n of pass bands and
t.helowestbackpressure_flow resistance)possible, These arej in fact, the
major marks'ofa "quality"muffh;r.
The firststep in seriouslyundertakinga progrmnof bench testing,therefore, lies i'ndeflnlng
the appllcatlonand operatingconditionsfor which the
candidatemufflerIn to be evaluated, The more precisewe can be in defining
these conditionsand themore narro_l
the variationsIn applicationand operating
conditions are, the better job _ cau do both In designing a muffler and In
bench testingIt.
We at SwRIdid a study some12 - 15 years ago for MERDEC (then ERDL) to
evaluatethe feasibilityof developingand utilizinga bench test facilityas an
Amy procurementold for severalclassesof more or less similarstationary
engine applications,The most questlonablepart of the effortwas simply to
define if themilltar_,
standardsenginesused in these appllcatlonswere sufficientlysimilarIn exhaLlstspectralcontentand the acousticpropertiesof
their exlloust
system thatany one set of bench facilitytests _old be of slgnificantvaluefor extrapolating
perfomance to a11 engines in the selected
class. Perhapsthe resultsof thisprogramwill be of Interestto thls group
in definingJust hnwA bench facilitymight be utilizedIn testingmuffler
"quality"and in definingsome of its inherentlimitations.
1
(I
In thisdiscussion,I regretthat time wlll not peomita fulldiscussion
and descriptionof the exact designproceduresused In evolvingthe bench test
facility(e,9,,the siren),to analyticallyprove _ome of the ass_nptionsmade
145
1,
(lineerlzationproceduresin extrapolating
acousticsystem response)or in providing experimentaldocumentationof thevalidityof scallngsome of tilecomponents, llecould argue oxtenslve]yaboutv1hereto locatethe mlcropbone(s)at
tilemufflerexhaust, ilevertheless,
theresultsof testingon the facilitymay
be _orthyof note. I shouldalso note thatresultsof the bench test program
_ere publishedin SAE Paper 771A, datedOn'tabor1963, aud entitled(appropriately enough),"k Donch Test FacilityforEngine HufflerEvaluation",
by I. J.
Schumaciler, C, R, Sparks, and D. J. Skinner.
The first step in the programwas to field test some half dozendlfferent
engines,and 47 standarddesignmufflersfrom some5 or 8 of the major suppliers of mufflersfor tileHIL STD onglnes. This testingprovideda data base
on the noise from the various standardengineswith exhaust sizes rangingfrom I
I/2 to 3 inches,data on the perfonnanceof varlousmufflerdesigns (seeTable
I), and data on the sensitivity of results to operating conditions.
Prom this point _ork turnedto thedesigningof a prototypefacility,and to
developing techniques IYhereby facllIty data might be used to imply how a muffler might perform on an engine, or at least show a means of differentiating
between obviouslygood and obviouslybadmufflersfor the applicationintended.
It was also recognizedat this polnt thatthe facilityhad to be fool-proofIn
the sense that "gimmicked"mufflerscouldnot be deslgned_lhich_ould sho_1op
well on the facilitybut which _ould notv_rk vmll on the engines(eitherbecause of noise or performanceproblems),
DESCRIPTIONOF BEi'ICilTEST COHPOIIENTS
A photographof the first prototypeof the bench test facilityis sho_n in
Figure l, and a schematici_ shown In flgore2. It nlaybe seen that in addition
to its noise testing feature,the facilityIncludesprovisionsfor makingboth
static and dynamic baekpressuremeasur_nents
on the test mufflersat various
flow conditions. In order to optimizeuponboti}the mechanicaland operational
aspects of the facilityand its componentpart_,comprehensivestudies_._re
made of these parametersin order to assurean optlmumcompromisebetweenfacility reliabilityand operatlonalsimplicity.Discussionsof the major components and the tests used to define ti_eir
operationalcharacteristics
are presentedbelow.
Siren fioiseSource - The heart of theacousticsystem is the sirenexcitation source,shn_n at (I) In Figure 2. Thts siren produceswlde band',almost "white"noise and is a constantpokersourceby virtueof the near erltfeel pressuredrop across It, Thls hlgh impedancenoise generatorIs used Ir_
ste_d of more conventional voice coil devices in order to simulate the impedance charanteHstlcs of an engine no1_e sourceand thereby simulatelo_ding
effects experienced when an exhaust syste_ Is attached to an engine noise
source. Olscussionsof performancetestlngof thls device are given in the
foITo_Ingsections.
NanlfoldSystem - The secondimportantcomponentof the facilityis an
acoust--_-'c'on"_tem _Yhlchserves to coupletest mufflersto the siren and
representsthe manlfoldlngsystemof an engine..For some types of testing,
thls c_npenentIs dispensable,and usefulevalnatlondata can be taken H1thout
I_6
It.
It serves chtefly to bring the absolute magnitude of the noise reduction
more In 11ne wltb n_T1erical
data obtainedin the field. For facilityquallficationtests, thls manifoldIs a speclaIlydesignedpipingcomponentas shown
in Figure 2. For othertests involvingthe designof specie]purposemufflers,
or for evaluatingperfor_lance
for a partleu]arend-ltemapp]IoatJon,
excellent
corre]ationwith fle]ddata can be obtainedby using the actualengineexhaust
manifold.
Effect of Siren Pressure and Speed - A series of tests _mre conducted on
the wide band siren to evaluatethe effectof operatingpressureand speed.
These tests showedthatthe sirenoperateswell at pressuresfrom 2 psi to ab
least 15 psi. The generatednoise o,tputvariesdirectlywitb the sourcepressure althoughthe spectraldistribution
is essentiallyConstant. The siren
operatingspeed has a decidedeffecton the spectraloutputof the siren. It
has been designedto producewlde band noise above40 cps l_hileoperatingat
apProxlmately240 rpn. At speedsabove this level,tilelow frequencyoutput
falls off markedly.
Mlcrop_h_ne
Positlon- Extensivetests_ere made on tilepipingconfJguratlmn'-f_-F-ea_]T'-sTz'_'-o'f-muffler
to evaluatethe effectsof microphoneposition.
A comparisonof mufflerperfor_nance
characteristics
measuredat variousmicrophone positionssllomcorrelationIs quitegood so Ion9 as the microphoneIs located in the acousticfarfield. The exact positionof the microphone]s not as
importantif one )osltfonis selectedas m standardfor each mufflersize, and
so long as t_e microphoneis not in thedirect noise Jet. Oased on these tests
the microphonelocationwas set at 45 dog. from the centerllne of the outlet.
Effects of C,
as Temperature- The effectsof gas temperatureon muff]or
performanceare prlmarlly--]:ri
twoareas,
I. Acousticvelocityvariesdlreet]y_dth the square root of gas temperature, and thus the cut-offend band-passfrequenciesof a givenmufflershift
in essentiallythe sameproportions.
2. Gas viscosityincreaseswlth the temperatureand thusdiss]patlon
elementsare generallymore effectiveat elevatedtomperaturms.In general,
this means that the percentdampJnoof each re,
filer will go up as temperature
increases(that Is, the 0 will decrease).
Test results showedtbat the measuredoctaveband noise reductlon_haracterIsties of the experimental
mufflersdifferedslightly_a_enmeasuredwith hlgh
and low tempeFatures.As antlcJpated,the resultsshowed that an increasein
cut-off frequencywas experiencedat high temperatures(450 F elf temperature)
as well as a slight increaseIn the hlgh frequencyattenuationcharacteristics.
The use of hlgh temperaturealr showedan particularadvantageas faras dif_
ferentlatin9betweenhighand Io_equality
mufflersand as suchdid not warrant
the added complemity to {he facility.
I|iqh Flow Tests - A seriesof testswere conductedto evaluatethe neons.
_Ity "of_'r
a-_'n-d"
t--'_fect of hlgh flowthroughthe muff)or durin9neoustlctests.
tests. The most pertinentresultsfrom these facilitytests conductedon a11
three muffler sizes show that the qualltyrnuffIers
can be convenient]},
differentJmtedfr(_nthe low qualityor (_nptysirenswithout reproducingtotalmuffler
m
tz_
t
147
flow velocities
experienced on l:he engine. BaSEdon these tests no apl)rectable
|lnprovement was realized frorrl the acoustical tests conducted under Iltgh flow
conditions aud as sucth this requiru,unt was u×cluded oll tile facility
design.
DESCRiPTiONOF FACILITY _fUFFLER
EVALUATIOIITECHNIQUES
lhe output spectrum of the wide band siren Is shown by curve A in Figure 3.
Shown by curve B o11tlHs plot is facility
Lmmuffled output v¢Ith a typical engine
manifold attached to the Oh'on. if now wo superimpose on this plot curve C,
vd_lch shous output noise of the siren-manifold
facility
_tth a muffler attached,
the difference between curves B and C represents the noise reduction afforded by
tile muffler,
Sluce the siren Is duslgned such that eacll octave Interval shown
is rather completelyfilled witl} generate.d
noise,speclaIlytunedmufflingdevices (as contrastedto high qualltymufflers)may be sl}owoto be relatively
IneffectiveIn reduch_gtotal noise,and a numerfca]ratingof noise attenuaClan can be ascribedto each test muffleron the basis of tileoctaveband noise
reductionmeasured.
In order to relatethe octaveband noise rcdu_tloefiguresobtainedfrom
the facility to muffler quality or loudness reduction, one must cc_pensate for
the variationof"ear sensitiVitytHtt]frequency,and the dependencyof thls
frequer_cy
variation_Ith absoluteamplitude. In the programdescribed,final
evaluationof mufflerquality tlasbased upon the reductionIn sane loudness
afforded by a muffler _Yhen Its decibel noise reduction properties are superImposedupona typicalenginenoise spectrum. In order to Illustrateboth the
concept and the procedure Involved, consider a muffler wlth facillty-measured
decibel nolsereductlonpropertiesas shmm in Flgore4. If now tm consider
thattileunmuffledexhaustnoise spectrumshown as curve (_in Figure5, Is typical for cnglnes_hlcb mtgli_use tbls muffler,we can attestqualityof the test
mufflerby
computingthe
loudnesslevel
(Inogees)that
thedb
eolse If
rmiuctionof
the mufflerdrop
wouldIn
producewlmn
superimposed
upan thls
spectrum
_(egrapldcalIysubtractt/_enoise reductionfiguresfrom the enginenoise spectrum,
we get the predictedmuffled noise sp6ctrumshown by curve B. lVilen
eacllof these
curvesIs cofiverted
to SAE sones,then the resultingtestedqualityof the muffleris timdifferenceIn Chose sane levels. For conveniencethe sane Ioudne_ scalesare plotteddirectlyon the octaveordinatesof Figure 5, and Itmay
be seen fr_nthe nonl_nearitlesof tim scalesthat r_uctlon in someof the
octaves ts more important
thau tn others insofar
as loudness (sane) reduction
ts
concerned, In order to supplyproper weightingto the reductionvaluesobtained for eacllof the octaves]some typicalenginenoise spectrummust be.used.
In orderto determinethe final evaluatlonFactorFor eacll
muffler _ubjected to these tests,one needs merely to s{_lthe sane r_luc_.ion
affordedIn each
octave,or alternativelysubtractthe totalcalculatedmnffIed sane loudness
fromthe saneloudnessof the referenceenginespeetnanshown. The cnglno spectrum used Is not crttlca},as vartat|onsIn tileband levelsused as reference
havea secondOrder effecton tileoctaveband _mlghttngfactorsused,
It may be seen that the proces:descrlbcdabove involvesflrst of all, the
derivationof octave band noise reductionfrom the bench test facil|t},,
and
then the _'Ightingof each of these nolse reduetlonflguresbased upon notse
i
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.....
....
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typical of tllose to which tile muffler mighL be subjected In field
The entire processmay be slmplifiedcenslderablyby graphicaltechI_w_$'uslng tile song evaluatlon chart sho_m In Figure 6. Thls chart agah_ has
eight betave band ordinates.
IIeasured muffler noise reduction values m(_ybe
' plotted d_rectly upon the ordhlates, and corresponding values for sone reduct:ion may he read dlreotly.
The typical engine spectrum _Yeighting Factors are
aut(_maI'.Ioally
]ne}udedIn the loudnessreduction(db) figureson each ordinate.
To evolve I:hemuffler qualityfactor (the sone redt_ction
value)using this cnart,
the process Is as follows:
I, Obtain octaveband NR figures for tiletestmuffler frowntests on the
bench test facility,
I
I
2,
Plot thesedecibelvalueson tile db ordinatesin Figure6.
3, Read tilecorrespondingsome reductionfiguresfrom tileright hand
scale of each ordinate,
4. Take tilealgebraictotal of all Inferredoctaveband sone reductlon
values. This is the quality factor of the muffler,
After design and fabricationof tilebench test facl]ityshown In Figure i,
an extensiveseriesof tests w_re conductedon a seriesof mufflerswith I-i/2,
2, and 3 Inch Inlet sizes, It was shown that when a sophisticatedslmuIation
of the exhaust systemwas utilized(for example,using the actualenginemanIfold betkmenthe siren and muffler),fucilltytests rankedqualltymufflersin
vlrtual)ythe exact saliie
relativeorder aS engine tests. Such numerlea)correIatlol!
is Illustratedgraphical
ly in Figure7, where loudnessratingsfrom
field data on the 2 inelltestmufflersare shown as tilecenterordinate,and
facil'fty
ranklngsusing two sone calculationtechnlquesare shown on either
slde. It may.be seen tilerboth field and facilitytests rate the mufflersIn
vlrtuallythe _ame order,and that the facilityeasllydlfferentlatesthe more
qualitymofflers(B-12 throughB-21) from the (=',ipty
shell (B-If).
Similar tests,but oslng a dlfferentmanlfoTdwere shown te rate the series
B-12 through B-21 In a differentrelativeorder,but tile)'
_mre still easilydifferentiated
from straight plpe sections or empty shells. Since the objective of
thls dew:lopnenttYasa deviceto attest go(rural
mufflerquality for use with a
varietyof manifolds,the standardized
manifoldllasadopted. The entire system
was thereby shown to be effectivehl differentiating
betrmenqualityarAlnonquality mufflers on a rather general hasls.
MUFFLERBACKPRESSURE
EVALUATION
The back pressurecharacteristics
of the m111tarystandardmt_fflers
Is perhaps the most importantsingleevaluationcriterionfor most end-ltomap(Jllcatlons. Since tilemilitarystandardmufflerdesign Is not talloredto a specific
appllcatlon,a compromlsein tilenoise reductioneharanterlstlcs
was favoredto
meet the maxlmomback pressureIlmlts. All extensiveseriesof tests were con_
dueled on the mufflersunder a varietyof both steady flow pulsatingcondltlons.
Data _.re ree_)rded
using both a _Yatermanometerand a flush-mountedpressure
transducer,and vmre comparedwlth fleld data obtainedidth a flusIl-monnted
149
III
transducer installed
in the engine exhaust system, The results showed that
under steady flow facility
conditions (with siren off), excellent correlation
was obtained between field results and facillty
results using either a flushmounted transducer or a water manometer for facility
measur_uentso The data
also indicated
that full engine flow rates need not be slnlulated to perfom
these tests and that the _ilount of flew required is dependent erlly upon the
resolution of the back pressure measurqngsystem. Comparatively hlgtlflow rates
(240 scfm) are required
for the large size mufflers
In order to obtain necessary
readlng accuracy when a water leg manclneter Is used. Alternately,
lower flow
rates could be used wlth a more sensitivepressuretransducer,but thls systc_i_
would suffer from the complexityof ca]ibratlomand data interpretation.The
corre]ation of steady f]ow back pressure measurouents recorded on the facility
to engloeback pressuredata obtainedduringthe fie]dtests Is presentedIn
Figure8.
AfIALOGSINULATIONTECtINIQUES
Another means for evaluatingenglnemuffIers,at least In tile
difficultlow
frequencyportion of the spectrtnn,
lles in electronicanalogsimulationof the
proposedmuffIer-manlfoldlng
conflguratlorl.
The most sophisticated
and weIIdocomentedbasls for thls contentionIn theSGA CompressorInstallation
Analog,
developedand bperatedby SouthwestResearchInstitutefor the SouthernGas
Association'sPipelineand CompressorResearchCouncH (Sea figure10). llhlle
the primary purposeof this analogis to simulatepulsationsIn the piping systems of reclproeatlngcompressors(to datesome 3000 such stud|noflarebeen
conducted),it is also usefbland has beenused as a tool for designand evaluat|omof engine muffler and exhaustsystems. Using this analog,the total flow
characteristics(steadystate and transient)of a pipingsyst_I_
suchas a muffler and exhaust systemcan be modeled usingelectronicdelay llne elements
which are slmply coupled togetherto slmulatethe acousticimpedancenetworkof
the exhaust system regardlessof e_nplexlty.Lumping lengthscan be chosen
arbitrarilyshort to accomodatewhateverupper frequencylimit is desired,but
plpe dlame:erdoes imposesome upper frequencylimitations.The simulationassumes one-dlmenslonalcompresslb]eflow,and is thereforelimitedin app]Icabillty
to frequencieswho_e wave lengthsare largecomparedto pipe diameter. For a six
inch exhaust system,tlmrefore,the upperfrequencylimit is on the order of 500 IIz.
It Is readily noted,however,that It Is preclse]yIn the low frequency
ranges where muffler perfomance Is dlfficu]tto predictana]ytlcally,
and
where piping interactioneffectsare most importanton muffler performance.
High frequencyattenwationis reIatlvelyeasy to achievein a muff]or,and once
low frequenciesare contru]led,the hlgh freqwenclesnoma]ly takecare of themselves. Standardacoustictheory(vlz. Ilnedduct absorptioneffects)servesas
an adequatetool to designadditionalhlghfrequencyattenuationif It shouldhe
desirable.
The processof slmnlatlngan exhaustsystem on the analog Is a re]atlvely
stralght-fnrwardimpedancesimulationusinga seMe._of analogies_Alere
voltage
representspressure(AC and DC), and currentrepresentsmass flow,
m
m
If w_ start wlth the equationsof motion,continuityand stainfor onedlmenslonal,Isotherma],compressibleflow,and comparethese to the electrlcaI
150
l
delay 11ne equatlons,we find thata very convenientset of analoglosoccur
wherain
'E1ectrlcalInductance=Acoustic Inortanco
_'lectrlcal
Inductance_AcousticCompliance
EIectrlca]Roslstancec:AcousticDamping.
Specifically,the electricalparametersof inductance(L), capacitance(C),and
resistance(R), per unlt lengthof pipe are:
L- KI-]L
A
A
C- K2_
c2
Ind
R . K3 M
where
n " flowingdensity
A,
pipe flow
area
c. acousticvelocity
M , mass flow rate
K ..constant
Using acoustictheory the same _et of equationsare derived,exceptthat
the resistivetern is assL_nedllnearof the approximateform
R
1.42
(_1_--)
I/2 __-_9:e
p _r3
as contrastedto the fluld dynamicviscousr_slstancowhich is of the fore
fc2 M
R • K3
Considerableexperimental_rk has beenconductedto evaluatethe relativemagnltude of the two resistivemechanlsms,and re.sults
show that for all pipe
sizes of practical cnncern (i.e., larger than capllary tubing) and for all flow
rates on the order of several fps ur greater, that the fluld dynamic tom predomlnatos. Thus for most systems,thenon-flowacoustic resistancemechan1"_is
(e.g., molecularrelaxation)can be Ig(lored
withnegllgahleeffect.
It may be seen by inspectionthatof thethreebasic impedancetermsdefined
151
(R, L and C) both L and C are quite linear with flow.
Since these two parameters
detennlne electrical
(and acoustic) propegution velocities,
an excellent simulation is achieved of muffler attenuation rates, cut-off
frequencies, internal resonances or pass-bands, and interaction
frequencles caused by attached piping,
The
only paranmter undefined by R and C is the amplitude of tile various resonance
peaks which are ¢ontrolled by resistive
damping. Since the R Is non-linear with
flow, simulation can be achieved either by inserting nonlinear resistance circuits
into the delay llnes,
or by linearizing
the R for the average mass flo_ rate II.
Experience
with many simulations
have proven elther
approach Is adequate,
The question v_h|chusually comes up at this point Is "I/hat about perforations".
Again. both analyt|cal
and experlmental data sho_vsthat for non-flow
acoustics,
perforation
size must be quite small before the elements become resistive
rather than reactive,
In Figure ]i perforation
Q is plotted as a function of hole size for various frequencies.
Ilote that hole diameters must be
less than a quarter inch before the R pred_nlnates (i.e.,
before Q<I).
In the case of flow through perforations,
analog data has been compared extenslvely
wlth laboratory
and fleld
data, and again the results
show that the
predominating
effect
In achieving
pulsation
damping Is the sdme mechanism which
produces pressure drop. Speclflcally,
the dynamic (acoustic or pulsation res|stance) is numerically equal to twice tile steady state resistance, i,e.,
RAC
2 X RDC-
2
al--_
I.l steady flow
Using this approach,excellentcorrelationhasbeen obtalnndbetweenthe analog and fielddata for perforatedelementacousticfilters. An exampleis
g|ven in Figure12 which shows the pulsationspectrumfrom 0 - 100 Hz for a reciprocatingcompressor, florespecifically,the data shows the envelopeof pulsationamplitudesas compressorspeed variesover a rangeof ± 10%.
Again,the problemof using such a devicefor evaluatingmufflerslles in
tilequestionof _Yhat
constitutesquality in a muffler. Althoughthe analogwill
accuratelymap filterattenuationas a functionof frequency,Includinga]I passbands and In(leraetlon
effectsof attachedpiping,the noise reductloodata obtained is farthat particularexhaustsystem. If significantchangesare made in the
manlfold,tailpipe,etc., then data can be _._odlfled
substantially.Figure13 is
one exampleof analogdata taken for a proposedmuffler design for a large
stationarynaturalgasenglne. Note that noise levels and spectracan be observedanywhereIn the system,but that as the piping configuratlonis changed,
output noisefrom themuffler wi]l 11kewlse change.
m
m
I
152
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AcouStic Response of PIDi_c3Systems
m
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LII_ inu_'fl_lv
_capinll
dt_clilrl_
_ill_tl3_
CIII_ tallplp©.
throush
g lil{lliip_
hi1 bi'ok¢ll
_l_ln_.
no_o
164
by
F_;. _* pcep_nta
Th_
inforl_ation
u0tn_
_ _u_,l
_lla
mnclo_ure,
and
_ heavy
outnLde_
In
withilt
Thl_
LnolaLlon
creaLLn8
1 dll^ of
particular
alld
zlet
full
at
ilia
iil_lfflet'
nlukl-dowlZ"
tho
tip
enSlne
"iuBBt_d"
2/3
Tim
tent.
bn
l:_pol_ted
run
upt
teat
_n ycl;
Irn[_t_oll
;
tho
.
cool
the
_uch
that
w/tth
until
ill
coIltK'oli_ll_
tim
ell_lnu
2/3
rated
_AI_ 366b
the
7.5 dBA at: 1.500
...
cau%
enfJ.tlu
_ppro_imat_ly
agreetnent
t©ut
on t_yfltcm
_
tempt:r_ture
iU
rno_e "live"
uolne.
7_ Kahnuot
dll!£_renc_
condlClona
? _or th_
Th_a
pipe
mode
rcquirttd
of
the: cMtau0t
Q) with
approl_tmat_ly
qutt©
l.n
o_u
nlld
r|_;i
rpm.
drive-by
which
FIB.
would
condlttonn
in
165
2250.
th_
th_
for
nur£ac_
nor[non
and
the
o_
_
as_in
wt_rk _heetn.
eM_u_nt
effect
bccot_
IE
Huffler_
lloth
th_
noitl_:
B _rt_at_r
n 5 dllA (llffurunc_
con_dQrl_blth
dif[ercncen
IIO_]
p_ta.
actual
accellerat:lon_
nhow
_ttrfac_
6t
the
tile
will
rfldl_tud
_y_tt:m
o_
nudd_n
7_1.5 at
that
a ru,ult:Ln
t_
copt_ln
the
Notice
rlna
_l_cr_u_:l.
(hitch
utal)Llizcd
.,.
1700
_ur[tlcu
attellutlt_on
nr_
Thin
..,
_rl_o_m_tl_ll.
Tlmtle
b_twnen
5.
whatever.
73 dBA at
_._ derr_n_traLed
p_.
...
or
o_
In_f_l_t'
th_
1.'1.8 .
(IMI)_
Valuta
of
about:
the
wan found
and
the
tllt_ 8ovt_root"
addcd_
to
of
_hap_
Then
off
up
to
particular
rpm.
c/itl{]
tJluwl_
warmed
much
'd/IV_
thi_
lt_ takt_n
r_nge
plane.
l'a
1_ allotted
b/lnd_
rated
thl/i
1_
conni(lered,
co_d I _t
Flfi,
of
peak
In
4noth_r
O_ C_m[_rllLtll'_
rt|diutnd
loild
ldl_:-mnn-ldle
tu B mode.
Th_tre
_unctlon
laird
fLguru
coJ_dltionn
Ill
and
III
operutit|8
becaune
mode
bo roport_ltl,
_
th/a_
Then
oy.tltcm
octave
load
oi_ the
the
n reflecLtn_;
ev/llutlte(l.
Lit ful.1
in
Tht_ entwine
e_hau_t
are
l_a
data
IJntlt_t' thu_e
eleinenCu
24OU.
over
rpm.
The
Dp_ctrUlll_
_erloun
would
I_o1_
field
treated
Th_
aceordin8ly°
._eoat.'t
_ro.m tile
t'l,m.
For
i_z.
2100
dollt_ ...
throuBh
one
at:
tllt_ [_ov_2rllOr.
1_ Important
Only
One othnr
2100
Ln full.
_l_flllltlt
t'l_n to
free
rated
be rel_orted
down
1_ aeotltltically
150
tett_pertiturun.
Ill
mode
I_tldtl
at
J.oLet*ntll
a _12 dll^ would
1_
l_
load
'dock
wt_ll
albove
n completuly
operati.nB
I;htl flllllly_o
The
L"ree field
enBtne
to
tltabllt_e
u,lii.
a
uyntcm
rnuf_lcr_
In
gfo_e
t_n(l
and
Ill
_|1
c55_Jncc
I
[ookin8
t|l_
_v(_
for
Lrock
thu
woruc
hiu
nur[zlcc
noltJe
t_
dllA
c,m
he
Lhu
LllroU:ll_
5.5
7{]
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/_B
our_tlC_J
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Th_
noJ. o{_
o_
lile|o_LIry.
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ave
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o
ObV_otl_|y
po'Jslbly
could
r_l[i
[ullcLLon
of
tlz_lt
into_
a3
look
_11_
hc
ux_L]l(_
7._
lZlltl
IIh1_12_2_/1_
lzl_
di£_/cult:y
o£
engine
ac,oLhec
lti
im
OVi!L'COIII_,
Lhei _, llJ_
LLmt%
]"lB.
at.
ldle_
_00-500
u_ll_lu_L
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the
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tiy_Lumu
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Ill't:
uy_Ccnl
w_
provide
evun
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while
_ys_;cl,.
o£
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(l_y_cc_l
or
r_cl_
_md
8yl_.emi_
o_hcr
_eric_
"problcnl_
cofnl)ol_:Nl_
_y_l:enl
.ol'J_
cre_l_i:_
J_l]crl:._l]ud
the
a¢cu_l
m_l{l[L_.]r
r;LdtliLed
open
O[ _ _hU
d[lA
a
dcct'cllt_cd.
_4B£cnl_#
by
uo['Eacu
wLde
_l_
I_ {110['(_
aiCOtl_LiCliLly
_hu
d_vLce
_),_e[11_
hlln
_h_l;I
more
popol,r
Ollt_
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ltlLeE_t_ll_(:d
_lnd
_uch
111
...
riot.*
_llld
_tlitl
d_!vi¢_.
w_.l;h
vert_.
ntlcII
Cllfi_
_.n (_ll_
LIic
_'J[}_.
I}EllllilC7
10
ltJ
I_COL_I_Ic
t:V&lJ.Utl_*_C(I,
166
__
,;i_,i
' _ _.,
WIJIrIJ
Lhu (:Olld_.L{ox_ V(_r)' probably
oL"
llWO_tlB,'zcud
ptll_
Co
])i¢l_l|)ll_e(I
/tJ_l'c_£_(l
d£1LJI
']'hat_t_
punchud
lip
chu
;HldL_;[0illtl
ptlrl_L_:ultlr
'j:ha
_or
l)r,:c_(mc/nB
the
¢llnL_'£1)u(;_d
L_I
_elZC
o_
wlCl_
I=_',
pLJaP,
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EucL]lec
fllOnlUll_UIII
o_
Lmlicncion
How
w_l_
l/ku_i_u
p,r_o_ll
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Wll0
_hc
noknc
0{"
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tl'uck.
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n truck
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lll,l_
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o_
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real
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point
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time_
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puddins"
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cont_o[I
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from
beat
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truck
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ruquited
melt
cartllin
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£nrel_d_d
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te.tln
componcnt_
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_ltb
ttn
will
al,o
f.PA :;ucfngo
Trnn_lmCt_ttion
Chicl_ao_
IlllJloin
Octobec
12_ 1977
I_oinc
5AF. pnp_r Ho. 770t|93.
nE_ll_u.t
19112 II_avy lltlt_ l'ruckn,"
(Ic_£_(10
become;
becomes.
ofislne-d_narnor_eter
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167
8
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tbo InO_'e
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e
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con[ormnnct_
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type
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it
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11 nnd 12,
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fly utlll_inH
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II
!79
BESTAV_LAB LEC_Fy
A _ENCI] q'EST FOR
[(APID EVALUATION
OF
MOFFLER
PEHFORMANCE
_y
A. F, Seybert
Dep_rtm_nt
o_ Mechanlcn_
Englnearln
U_Ivera_y
of Kentucky
Lexington,
_entHcky
40_0_
_-
_sf
9
[
I HTI]ODUCT
The
United
S_ates
general
provisions
things,
these
/or
the
be
the
technique
It
shown
that
information
ns
where
acoustic
such
outlet
or
the
nound
dlt3tance
from
and
ml:;underntnndlng
some
factors
system
effects
suitable
_
n
some
descriptor
tlvely
In
the
tail
Flgure
We
for
how
engine
as
in
pipe
and
the
factors
the
wlthll%
is
a
i_pedanee
Per
be
keown
overall
i,leauured
radiated
in
:]sums
determining
that'
the
space
at
be
industry
ovursll
We
if we
by
by
to
workabli:
example,
other
using
lengths.
automotive
rational,
predicted
with
point
e[Inentlnl
labeling.
not_rce
the
a
SYS'/'EH PERFOI_IBtICt_
There
in
he
il]fluencing
some
p['esunts
characterist[c.';.
pipe
power
at
to
associated
_nd
can
can
sound
pL'odncts
problems
muffler
other
methodoloqies
of
eoajunction
outlet.
it
the
EXIIAUST
pressure
to dev01op
muffler
of
"perforlnance"
Yet,
a_e
of
i_ul)lisIled
Among
test
performance
impedatlce
of
for
performance
1 interrelate
psrformanco.
if
system
IHFLUF.HCING
_$ynt(:m performaeco,
plpe
.,
engine
FACTORS
1 shows
soi_e
sy:]tem
characteristics
need
ha5
I1].
characteristics
tl]e measurement
exhssst
such
the
exhaust
hqcnc],
standard_
acoustic
JIleasur_.d muffler
FlgL_re
•
labeling
discusses
of
for
|JAC_GROUHD:
i
the
paper
prediction
Protucl:ion
indicate
of
This
novel
is
noise
provisions
labeled.
with
l'nvironmellta]
for
ewlluation
IOH
cxh_lust
some
mild
on
tall
a
fixed
confusion
how
the
exhl_ust
ul_deratand
t|]e:;e
test. m(:thodology
know
an(| [;oUrcL; Strength
qsaetltaaffect
e_haust
182
.
!
i
.'
f
!_y!_toIII
Jn
|Jor[ornl_lliCC
which
such
the
as
the
an
cllgine
test
pcrforlLl_ulcc
to
by
devclops
We
factors
pair
our
divide
factors
effect
tion
well
e×haust
can
be
for
using
accounted
and
examples
classical
diameter
Ically,
e_eept
results
are
muffler
for
e|laracterlstics
very
reasonably
simple
R_NassL
t_chniquus
• Crocker
system
silica Stewart
advances
two
the
can
categories|
theory,
data.
latter
Source
category.
systems,
propagation
and
and
the
radia-
to
evaluate
[3) h_
in
be
determined
which
ease
imperanalytical
accurate.
modell;ig
[2]
rce ontl7
et
model_ng
_:xpaeslos
oQ_:r
muffler
Davis
system
MODF, LING
ha.c evolved
analyzed
approxlmatiens._
_n ex|laust
msst
geometries,
I',XIIAUST SYSTEM
parameter
fJound
we
acoustical
of
Thus,
let" labeling.
1 into
acoustical
on
test.
muff
empirical
order
known.
111 :Jesoral,
yearn
with
llke
in
behavior,
for
Figure
would
bench
system
proven
for
are
plpe:i i,re
in
we
eouFce
Jengt|is
the
suitable
listed
strength
length
exhaust
methodology
factors
tail-pipe
s_,stem
_lld
way
for
fFom
exhaust
similar
used
source
obtaizncd
ifllp_d_l_Ce
a
and
be
of
accounted
must
hand,
of pipe
is
be
source
t]*_ other
in
Is
data
overall
source
m_thodelogy
noise
The
the
which
bench-test
e|uctroJiJc
|_t'ec|ict
available,
test
the
that
and
[or
o[: pipes
simplified
can
to
understanding
thi*t can
impedance
On
are
an
a
loll(Isr_e_ll:cr.
used
el_giil_
c]evelop
with
or
variations
stand_rd
increasing
replaced
be
_lly
for
pos_Jl,]y
d_ver
information
a
and
is
would
foL"
_ceount
that
We may
ncoLlstJc
¸ bench
strength
t
systems
al.
by
[4]
using
made
applying
chamber
revlew_,'d
a period
exhaust
and
of
about
50
lumped
significant
travellng-wave
•
sld_:-braneh
system
1
1
modeling.
configurations.
fout'-l_olo
'in
techni(luo5
exhaust
The
to
I:k)llowlnq
apply,
_ystem
system
are
theory
used
seems
theory
the input
The
called
and
relating
P1 and V 1 are
the pipe
volume
plpe--all,
dlameter,
'i
entrance,
velocity
nt
ai2,.a21,
and
exhaust
that
in any
section
The
volume
the_e
pipe
input
and
velocity
very
be
powerful
easy
litlear, invariant
rolz_ted by Eoul"
of
length
output
at
and
_;y_tclI1 design.
parameters."
of pipe
quantltiea
PI_alIP2
whore
['or
the "fouL"-polo
S, ["lgure 2.
pressure
expressions
method
can
(]c_velopI_lctnts
16].
i_
quantities
a _traight
Sullivan
Igaras]l]
the concept
electrical
ltccollt
by
on
consider
the acoustic
by
10 based
oxampl_,
_rea
reviewed
ideal
parameters,
appli(!d
_.'[;[:c_l_l InOCl(,] ill,1,
an
and output
[51
lqara:;hi
be
"system"
seetlon_l
to
_,ocl:,
Ox]laost
modeling
four-polo
and
Four-pole
to
this
As an
L and cross-
quantities
each
are
end of tile pipe.
are:
+ al2V 2
[I)
Vl_.n21P2 + a22V 2
(2)
the ncountlc
and
P2 and
the pipe
pressure
V 2 are
e_it.
and _22--are
and
vohlme
the aeouL_tlc
The
four-pole
functions
of
voloclty
at
prei_sure and
paramotcrt_ for
frequency,
the
pipe
length:
_II_COS
kL
el2 _(I,c/S)j
sin J_l,
(3)
:'"'
i
N
A21_(Pc/:;)J Sill I_.L _122=co:J kL
___ _A_,_,_/A_._
_
_:_,_'__';:
I_.,
,,:-
"
whore
km211f/c,
J c]_rlote:J
c
is
_m_lglllilFy
l'o_"complex
p_rameters
can
.lind
,';pond
of
:;trend,
r, in
Ihc_ density
oF air,
al',d
quanLJky.
_ICOUStJCfl]
be
SIIOW_ [7] that
point
the
COlnpLlted
the
S_'.it[?lll:] (e.q.
[[0111
a muff:let)
the
JllIpc?fl,lllCe.';.
Illl)d_ll['L'd
foul'-pole p_*|-nli1(!tel-s
are
related
four-po._
] t
to
C,lS be
the driving
t_LIII._][OF
i[llpe(]anceG:
all
ZII/,'I2
dl2=(Zl] 222-Z12)/ZI2
(,I)
'*22"I/Z12
where
ZII and
i_to the
Z22
pressure
V2 nL the
omit),
thell
havo
theoFy
in
Thin
terms
of
i, the
sotlrco strength
Z_ ]s
im[_edancus
a_; tile
the
_-espcctively,
ratio
of tile
acou_;tic vohtme
tile
vt:loclt_,
four-pal(?
paramet[?r:i
[or
the
Gy!ltcln.
Is tlsefel ie eelnbillil]g"acoestical
overall
:itlb-
:_yst(:/ll
l)y rep_'esentii*g an
nxhaust
foul,-pole I_aralnetc!rsits
uhowll i11 Pi(lure 3.
engil_e ._eerc(-"impndance
and V
(the
_|cotlstlc volume
tile radil,tlon
Ioo_.ing
the illlpedglnc(.'s
of a complex
C:llll)c illut;tra£cd
varlo%l._ s_absyni:cmo are
and
acoustical
stlch a.q ll%ufflere i_nd I)ipetl, to obtain
Fig_ire 3, Z
:
tile elltF/llleeto
If W,.
_ Call measure
we will
performance.
system
point
systen* at tile ent_'ance _3nd exit
Pl at
'filefour-pole
systems,
the driving
tile trl*n.'lferiltlpsdaece (defined
acoustic
system,
arc
ncoutJ_ical
alld ZI2 ill
O22-Z22/ZI2
re]selL Z of
_'epretl[_ntedby ca:_oadcd
ilnpC(lnllC(2
of
the
$n
i_i thn engine
th(! eliglnu).
Tile
refit-pole parallleter_;,
t;lil pip(:.
['oF |:he [ollrd
pole
model
parameters
shown
ill F]gtlrt: 3t V e,
mu._t I)e obtalll(:d
Z,,t.
l_llcl
the
t:Inpiz'ically; but
muffler"
tile
fouL'-pole
]
foul'-pole p/tt'arlleters
185
:,
'1
i'
,',LLj ...............
""
' .......;......
i"'
for
the e×hausL
impedance
and
tail
Zr is known
Equations
i and
pipes
from
are g_ven
in I_qLIatJoIl3.
The
rlicllation
theot'y [8J,
2 can be ivritten in matrix
form.'
vlJ Lan °nJLV2J L ]Lv_J
|,ikewlse,
velocity
tile roi_Itlon_hip
at tile entrance
between
and e_lt
2 L%l 1,2_
j I.vji
Equat_on_
5 and
Pl -
"
_his
°
N ,
[i
p.rocess can
6 can
A
l_
o_
pressure
the rluffluz
and volume
can be e_|Jreuse(! as:
j
be combined:
P3
be continued
hi"(oI(
LVlJ 1, J/%J
acoustic
to yiehl:
I
c.,
),,.
y':,
,
r
!
21 enJ
I:
B¢cm_=e
from
Lhe gour-pole
theory
matrix
pnrametern
or expcrlnlcnt),
D are
nl_o
known..
Pl_d_iP4
for
A,
the overall
We can
rewrite
Ib
and
C are
four-pole
known
(either
elements
Equation
of the
8 as:
+ d12V4
(10)
VI-d21P 4 + d22V 4
•We. know
alan
equatioos
that
with
Equations
p4,YeZ
Th'e Insertion
the acous£1c
_nsertlon
system
exit
exi_
o_
Tha£
In;
lO
and
Iomn
11
to
Of
exhaust
(_,g, Equa£1on
the acou_tle
12) with
manifold
who_
|
:_:.:
PI'
and
VI'
V4 yiold_z
(12)
for
One way
pross_re
the acoustic
no exhaust
_L07
,
.
thene
parnme£er
nysLems.
{p(_ .
/
combining
eliminnto
(It) i_ a usQful
In to _ompare
the oxhannt
VlmVe-Pl/Z c.
/(Ze(d21.ed22/Zr)+(dll+d12/Zr)J
performancQ
loss
and
P4/V4_Zr
(ii)
mt
_valunting
co expr_ns
t-he e_haust
pressure
sys£nm
P at the
is present,
q'ho
aflaloqoll!i
showll
Jn
exhaust
CII'CLI
I.'igure
J L rot
4,
where
IllallifoJ(1.
_f.°
insertion
Equation
Z
[_rOlll
/z .z
The
loss
till|
ell 1111o wl I:h
is
the
|_lqUF[!
radiation
equation
is
Log
variables
given
pipes,
found
by
combining
known
how
we
the
from
measurement.
F.
Ross
University.
(
of
have
theory,
12 and
Id with
and
we
the
as
appropriate
wlll
method,
author
The. the.oretleal
the
the
Ray
W.
i_l'_d
As
exhaust
the
mentionud
tall
Z r,
but
of
pipes
the
u:lunlly
be
Impedance
"two-mlcrophone,
about
llcrriek
tall
and
must
method
to a:J the
for
:lystel, performance
impedance
a novel
dew_loped
exhaust
performance.
,Lad cxh(]ust
Impec|aneen
was
basis
exhal, st
radiation
referred
at
ayatem
information.
for
describe
the
PAI_AfII_TP_RS
mafflu[,
tile muffler
technique
the
predict
(15)
between
MUFFLER
can
i_i the
and
I
exhaust
parameters
section
This
affects
englsu,
four-pole
random-exeltatlon"
D.
tile
[
re]atlonship
I".NGZHI'] AND
that
_mpedanoe
This
the
each
OP
combination
source
mean1_red.
'
clearly
and
providing
_:ngine
Equations
_u(121Zr4d22) Ze+Z +(dlIZr+dl2)
r
15 shown
previously,
are
of
(2
shows
.Equation
a
hnpedL_ece
JB
\
MBASURP.H|?.NT
for
:;yt;tt_ln
4:
'
_ystem
oxhzlllat
13.
IL=20
_his
iio
two
years
ago
Laboratories,
technique,
as
well
by
Purdue
as
a
literottare
su_'vey
properties,
+;"_::v:
.. r'
i_
aspects
is
The
is
cmphnslzed,
prediction
with
of
side
the
phones
as
can
i
muffler
operating
the
tile muffler
effects
and
am
stored
A
In
spectra.
The
determined
the
[Jractieal
will
data
aldo
muffler"
input
theory.
of
the
of
Figure
real
if
the
not
flow
muffler
detcrlnlse
tile reflec:]hoilld be
suitable:
for
:;o++md
or
and
To
the
Past
other
straigl_t
6
shews
189
{re:listlvo)
the
and
the
tail
introduced
micro-
The
and
flush
mlcro-
located
mlnJmlze
signals
are
Fourier
19J
is
and
muffler
to:it
pipe
moui1ted
(to
incident-
a
be
a
Two
50ms
t(:ohnlque
into
may
pressure.
possible:
Analyzer
into
and
TI++C mlcrophon{_
pipe
also
necessary.
appro_imat(:ly
spectra.
impedance
can
(using
introduced
Air
the
impedance
these
one
can
parameters
obtained
are
is
physically
the
be
It
processing
in
four-pole
coefficient.
of
of
itmfEler
, clio
loss,
tested.
pipe).
spectral
from
with
be
of
transmission
noise
a Pearler
tile sot*ncl flsld
theoretical
th(_
perforiilanee.
sample
is
the
in
the
propeL'tics
+
a chmtance
separated
to
pipe,
the
time
conditions,
of
compared
only
sy._;tem pz'operties
which
same
:;ystem
to
Inside
processor.
be
;
a_'r_uitlCltlent
the
random
tile source
tochmiquo,
and
the
5,
on
decompose
wave
e×haust
this
b22 , c_n|
as
these
located
digitized
[9J
,ic[31]stical
IllUassrctnest
and
£*bsorptios
that
Figure
actual
attenuation
(PFT)
to
I)]th
At
such
Lhe
from
b21,
the
overall
of
are
close
Jlii!*l!;llr(:
l);l[icr
fo_
5.
4).
and
_e_errlng
pho_os,
t('}
of: exhaust
u:;ed
b12,
however,
simulate
LJI;i_LJ
r_JCellt
impedances
parameters
ooeffleisat,
to
a
['igu_'e
Equation
muffler
one
ill(,!;
mcasuremeilt
is
bll,
like
on
of
setup
muffler
muffler,
equations
tion
the
shown
the
the
other
to
(:_perimental
determine
kcchil[
hero.
properties
for
other
subject
tllo
r_lated
presented
be
of
Transform
aged
re,looted-
parameters
accuracy
pipe
ezperlmontal
JJlisg_nary
tO
was
of
the
measured
tll|d
(Eeaetlve)
.
comporlest_3
o]:
bctwecn
t]_eoL'y
a_d,
st
This
d_ita
and
the
the
and
same
plpe
]r_Ipelance.
u×periment
timu,
sLl|_I_o_ts
tail
iJipo
t_i]
The
vel'if'ies
.,;hows
earlie_
thc_
the
accurncy
statemellt5
pt'opertle:_
cotlh|
be
exc(!|JenL
aCil'd!emunL
u×]_rilneZ]ta]
o[
which
the
Lheory
[]0].
th,lt
e:<hau_L
notoc]
accounted
[o_
L_chllhjue
I_,
I_._iilq
theoretical
models.
le
wa_
_i _ecolld
measured
_talldlng
and
wave
sgaln,
technique
ratio
Figure
ho_
be
of
and
to
agreeiT]ent
might
thls
traesJllissios
method.
_J shows
measLlrumeNt
th_
colnpnred
exc_llent
Fig_ir(.'
hut
test
used
engln_
other"
obtained
Thi_'_
data
_t _J_ototyi_u
i_
the
iiLu_I!ler
conventional
l_re_cntcd
in
FJqure
7;
noted.
measure
_o_rce
is
o_
using
two-ii1icr0|)hollC,
to
work
dat_l
is
tho
loss
_lldolll-excitatiol_
engine
imps,dance
underway
aL
soul-ce
impedance.
has
sot
yet
the
_nive_sit_,
The
beun
demoesLratcd,
of
l_entucky,
9.
The
two-micropZ%one,
advantages
ow_'r
ConvestlonaJ
conventional
techniques
traversing
probs-tllbe
addltlon,
random-c×cltation
such
nols_
made
within
eallaust
used
Jn
two-mlcrophone,
those
problems.
random
e_clt:ation
essentially
methods
dlscrete,
A
pipes.
and
the
is
dlseret{_
important
of measuring
standil],_
that
may
are
wave
of
Influence
Tile statJ0nary,
advantd_ge
_ised,
in
thc
frequency
frl_qucllcy
aspects
the
acou_tic
isethcd
p_'onertles.
[lll
c]el]ign.
use
In
me.*suremest:l
wall-mounted
microphones
£echnJciue
avoid
reso]utiol*,
acoustlcal
proper_ic'_
l_ecsulJe
are
_]Olll_lls. l'}Ith COllVelltioeal
(slnuilo_da].)
of
sevcL'ill
microphone
i_) increased
tile computed
has
con|plea
rllnclol,-e_cltntlOl]
second
contlnu[Jlls
using
as
microphones
flo_-generated
the
methods
technique
Lusting,
acoul_tJcal
d(_tn
p[opertie:_
.is also
(i.e.
.1.90,
'11
;
i
II
OCCIII"_'JlIIJ
J)eIiwoon
advLlntage
J!i
and
[l'e(iLl(_nci,,,;
increa'.;ed
the
becauscJ
to|it
_1_._!.
(_ta
is
)
c,'lll
])(_ (_vt_r|ooIie(].
I!H::lU!;e
_c(]uired
r,n_dom
ine_l_tlrL.tllents_]ro co_ducto(l
Of
111o_sul'enlc:llttil!h_ _t_7._ ll(_L'LIO_l
to
6
actual
thJ z-(J
i:;
Lisud,
,ltltOlll_Lic,_lly,
l-a!_Jdly.
Olll V aboklt
obl:n[_
the
7 SOCOll(Is
(latil ill [_igLlres
aIlcl 7.
The
[%.'o-micl'ophon,:,
design,
alld because
technique
:
rant
:
number
should
_Ispect
of
of
any
'l'he above
llll_¢/ll[)_e
_.s
Ox|la_Ist
(e,g.
or
to
Int_ffler
ro:le_irch
1_ibellng
itlea:Jure
engll%e
Infle_tlon
nource
rnmaln:l
be
,_oll_ce
l_l|_(:_h_nee?
ty|)o?
Lo_(l?
but
Spne¢|?
effects
or! flo_
and
effects
i11 pre[llctlng
J:; an
used
by
iZlSe['tion
t|leocy
iIlli)or-
a
]arge
tile country.
Io_'_!_
ill
_'I
IJerfol-lliD_ce,
every
lolls
engine
can
be
ill COlljLinctIOll
|)el:ore a test
is
It
and
DredLcted
%'/ith oliII)i£1cal
15,
examp]e,
_ncom[llete.
how
aCellratu
our
in
_:¢_uation
gr;l(|lellt:l,
Inllel:tlOll ioli11?
Can
for
knowledge
pred/ctlng
the
111tlflt
%40 _11o&7 engine
_]otlFco llllpedilllCe (lepend
derJv_itioll of
telriperatl_ru
11%etllo(|ology sult,_ble
for
qnite
engine
The
insert_o_
for
the
LAbELlinG
s_,ntelll
lens
test,
This
o£
ill
Imped_mce:;,
F.quatloz]
Doo_
tile
eXll[tLIlJt
Jmplemented.
ilitpedance
lofl,_ llslng
of|"
t-o be
t'Ol% I.IUFFLI.:R
in.']ertion
tlS_llg provel]
(:an
_
tIhqt
D/'ctlictincl
ellglllC! an(] muffler
Nuch
"hands
results.
that
/,]I_TIIODOI,O¢3y
llystent conflc]uratton_
for
n
J_; :;iml,lc
4z-Onl,:; in (lJ[[c,i'_:nt i-_g_o;is
llld_C(l_OS
for
F_cjliatJon 15)
data
technique:
(HGcu_Iol]
p_'actical
J.*_e.4sential]y
I1J(JI11y colls_stent
A TEHT
[:_,lt'illlteter
nol:
test
testing
[nd/vich_als
-
K'ar_dom-(.::eJL.]tL(nl t_chshlu(:
the
y]el(1
SUt.ltlAIW
of
,-,::c_itnth_n
.111(] IJr(_c(:l;_;c41
illtp0dance
A
15
oi% e_gillo
neglected
the
lJo_l illlpO_t_lnt are
these
uff_:ct::l be
these
IIICIIILIc0
191
_'ce__;_G,._;i:_.'.; .___i
2:::"-_,;_,.:;;.,_:.',_
__ _:._ _'_-_"_"-'-_
_-'_:,..o,_.
_.,_7
__,:1:,,
,,,.:i._:i_i_.ii_;i
I
:
L_
L. "
using
_ome
called
type of
"cotrectJ.on
to answer
some of
it appears
those
_Ising a semi-empirical
au a basis
that ad¢lition_l
reseaz'ch is needed
questiolls al]d to test tile feasibili£y
te!_t methodology,
foi" muffler
labeling,
:i
i
192
, t
i,'_a rJgorou'J analysis
fo_ here?
_n conchlsios,
pnper,
),1(:Lots"or
such
as described
of
/if this
_ _ _:_':_T_:•_
1_
,
_ =
,
__
,
"%'_!_,
;i!/-i_!_
:i
i;iI
IZF FI",r_EFICI',";
I.
._
Register,
Jilnu 22,
1977,
_,
l)j).3]722-31728.
2.
Stewart, G. I:., "Acoustic
1922, p. 528.
l..Pnve
PilteL's,"
3.
Crocker, I.l.J., "Internal Conlbsstlon l:l]gille
[:xhaust lhl/fling,"
Procedlnq_,
Nolse-Con
'77, |vashin(tol_, D.C., Oct. 17-19, 1977.
4.
Davls, D. 0. Jr., Stokes, G. M., Moore,
D., Stevens, G. L.,
"Theordtical
and ['.xperimel_tal Investigation
of Mufflers with
Comments
on I_nglne E_haust Muffler
Design," F_ACA 1192, 1954.
5.
_garashl,
J., _oyal,a, _I., _undamentals
of Acoustical Silencers
(1), Report No. 330, Acron,'_-_tlca[-l_esearch-qTist., UnlQcr.J_Tf-of
Tokyo, One. 19_0, pp. 223-241.
6.
Sullivan,
J'° I'I.,"Modeling
of Engine l_xhaust System _olse,"
Nolse ancl Fluld s En_Ineerlng,
R. lllekling, Ed., pp. 161-169.
7.
llschevkln, S. _|., A Course of Lectures
MacMillan
Co. , _lew--¥0rk,--_9-63.
8,
Lcvlne,
II., Schwinger,
J., "On the Radiatloa of So%lad from au
Uuflangn_l Circular
Plpe," Pl_s: Revlel_!, 73 (4), 1948, pp. 383406,
9.
Se_,bort,
A. F.,
Ross,
D. F.,
"F,×pe_ime, ntal
Dctermln;|ti.on
of
Acoilstl_ Properti(:s Using a Two-Microphone,
Igandom-l'.xcltatios
Tsehnlqun,"
J. Acouat.
See. AI_., 61 (5), May 1977, pp. 1362I_70.
on
Phvs. P,
eviet., 20,
tileq'heor[ of Sound,
i0.
Morse,
P. M., l_gard,
I(. 0., Theoretical
IIIII, .1968, Section
9.1.
_I.
ASTM C384-50,
1972, "Standard Method of Test for Impedanc(l and
Absorption
of Acoustical
[laterlals by the Tube Method."
193
g
•%•[•
.Federal
Acoustics,
NeGraw-
E_GINE
CI|AF_CTERISTICS
EXHAUST
PIPE
C]IARACTERI
STICS
SOURCE
I;,IPEDANCE
SOURCE
STRENGT]I
MUFFLER
CI!AP.ACTER_STICS
TRANSHISSION
LENGTH
LENGTH
LOSS
DIA_IETER
OTHER
Pigure
m
i.
Some
factors
....................
/
influencing
TAIL
PIPE
CHARACTERI
ST]CS
_
RADIATION
TRANS'_X
ISSION
IHPEDANCES
OUTLET
FACTORS:
exhaust
I.
Gas
2.
Temperature
3.
Rends
4.
Shell
system
DI_]ETER
or
Flow
Gradients
Radiation
performance.
vl _
F_guro
""
;?
2.
......
Vl
Straight pipe of length L with acou_tlcal
varlab1_s P
_nd V_ at the pipe ent_nnce,
P2 and V 2 a_. the p_[)o exit.
_nd
E_IGI:_E
I
EXIIAUST
_
PIPE
MUFFLER
I
I
P1
VI
Figure.
I
i
:ill
';,
.....
J
3.
Reprcnentation
i ....
P2
all
a12
'*21
a22
of
engine
•
•
TAIL
PIPE
OUTLET
PIPE
i
%
/
P
V_
b12
b21
and
TAIL
exhaust
V3
b22
system
u_;ing
I
%
P4
Cll
c12
c2I
c22
foul'-pole
,_,
theory.
ip
_o(,> E3
V
F3
/
Figure 4.
rlod_l Eor choline arid cxhal_'atmaill[oldwithout
197
I
"=
I0'-12'
_"
AIR FLO_I
I',,{ITErlOISE _
_
SOUN_
.SOURCE '[_
l....
I ,A_'I/_LYZER
Figtlr(:
t ¸ _,.,
!;:'.;,.,,_'i
i f ,
5.
_1(!_:_urcmRl_t
of
1-----7
I_]ICROPrlO;IE
Af'IPLIFIEPS
Inuffl()r
ch_|r_Icteri:]tic_i.
"--I'lI CROPI-IO_IE
S
I
, 2
_.
_
0 _
_II
•
_,_
_,
.
%
<'_
b°+
• e
+ eeee
0,,,
+++.'+ +_e
, +
+ o P'+ oQ +++,+ <,
+
+_j+,.m+.
,_ .++,,,+
+ ,I++_
_
_
+++ _ . _++.++.
,• +,
•
++
. ++.+
+?
o"
c_ +.u+-
,,a
,
%++,;:+.-+
,.\
+,f_+ ,+
+
I.ItE_IUEP+CY
(IIZ)
Figuro
,.,
L
7.
'/'rnnsptls:i.Lc+r, lo:is of
prototype
microphone,
random-exoi£atlon
wave+
.Iotho(l.
200
......
mt;ffler;
.l.,.itwoIne£ho¢l:
O_u_andltlg-
[_
_-
"!HITEtlOISE
SOU%SOURCE
FOURIER
L
ANALYZER
I
rIll
i C R_,PI,OIIE
!
/_KPLIFIERS
Figlzre 8.
]
_1_i_suremerlt of
-j _-
\.
rll CROPilO_XE
S
eDgiIle ,_ource impedance.
["I_LIL'O
9.
]/l£e[/lal
[111ivel"_;ity
COl]lb_l:Jt_oll
o£
C_;(IH]o
Kellt_leJ_y,
=02
ll()j:;(?
l'o._o_|rC|)
_lt
th_
Analytical a_id Experimental
Testino
ProceduresFor QuietingT_vo-Stroke
Engines
by
Donald L. MargoIIs
AssistantProFessor
DEan C. Karnopp
Professor
and
lhlrryA, D_yer
Professor
Departmentof Mechanfca]Engineering
Universityof Callfornfa
Davis,Ca]Ifornla95616
I
|
ii
203
Abstract
Tileresultsof a researcheffortsponsoredby Ya_rlaha
Motor Co. of
Japan arc presented,
The n_atn objective
of the project
was to quiet
t#IO
exhaustfr_tm2-strokeengloesl_Ithout
sacriflclog(toomuch)
performance.
Analytical
and experhnental programs were undertaken to acquire
a fundamental understanding of 2-stroke engine dyflanlicsD to n_asor_ and
predict noise levelsassociatedIYttli various exhaustsystems,and to
designinnovativemufflings.vster,s.
Ibe resultsshow that predictlng
absolutenoise levelsis difficult; however,comparativestudiesare
wellsuitedto analytlcaltechniques.
Primary empi)asls
is placedon experimentalprocedureswhich allow
tesUng of mufflers
operating engine.
in an anectmtc nhumber and In the absence of an
One of ti_ese Is a postttve
level source to which Irlufflers
displacement acoustic
can be attached and sound power levels
detennlned.This procedurewas used to corroborateacoustictheory
and to determine the extent
to which acoustic theory could be used in
the design of engine mounted tnufflers.
Anotherprooedt_re
involvesthe nse of a rotaryvalve,and compressed
_lr
to generatevery realistic
(motorcycle-like)
large amplitudep_lses
with theproperthrou.qh-flow
and frequencycontent. This very clean
experip_nthas proventu he a very excellentmethodfor duplicating
actual engine tests.
It is anticipated
that further development will
resultIn a variabledisplacelnent,
variabletltrough-flow
rotaryvalv_air
motor that can he used to accurately assess real muffler
m
20z_
,
.......
performance.
Introduction
Under sponsorship of YamahaMotor Companyof Japan, a re_,eiirch effort
was initiated
silencing
at tile University
of two-stroke
on tile project.
engines,
Tile project
of California,
Davis to study exhaust
The ti_ree authors were colnvestlgators
resulted
In several publications
(rofs. [I] *
throughI/J), two patents for Yanlaha,
and supportedseveralgT'aduato
researchassistants.
The principalobjectiveof the effortwas to quiet two-strokeengin_
eahaustswithout sacrificingperformance. To accomp|Ishthis goa],the
researchwas channeledinto several-parallel
paths. One of thuseiw_voIved
a major analyticalund experlmen_a]study of the gas dynamicsand mechanical
dynamlcsof the two-strokeenginein order"to gala a fundamentalunderstanding
of its opera;;lon
and why It produces(so moch) noise in the first place. Thls
stud},Is representative
of refs. [I], [4], [5], [6], [7]. Anothermajor
researchchannelinvolvedanalyticalmode]lagand experimentaltestingof
m_fflersIn the Unlverslt}'
of California,Davls anechoicchamber. Thisaspect
Is describedIn refs. [2] and [3].
In the followingsection the operationof a two-strokeenginew111be
brieflxdescr|bedfn order to gala a qnalitatlveunderstandlngof tile
noise
genera_lenproblemsinvolved. Following_Ids, the anal},tlca]
engineand
exhaustmodelingare describedin some deta|lalong wlth noise predfctlon
models, FlnaI].y,
the anal}'tlcal
and experimentalanechoiccilalnt?_r
testsare
presentedand the entireprojectsum_larlzed
with empl)asls
on reg_Iator¥
tests
:
for EPA monitoring_nd centre)of motorcyclenoise.
*Numbersin brackets[ ] refer to references
L
Two- s trol; e. E__ 1_1(_.,
_ era t i on
Tile
different
t_to-stroke
crank
engine
positions.
is shm.m in figure 2,
boon ignited,
is shc_o scheJtzatically
tile piston
The associated
h} figure
conventiona|
|
for
expansion
two
chamber
Assunlinga fresh charge of ah'/fuel mixture has just
is driver)
doiYtlli,lrd
on
its
pal#of
strol,
o.
it
f|rst
uncovers tileexhaust port (EP) arldJilost
of the exhaust gasses are forced
into tile exhaust pipe due to tilestill re]atlveiy
cylinder.
high pressure inside the
Also, as tilepiston moves dolYn,it coJnpressestilefresh charge
of fuel already resident h) tilecrankcase. As the transfer port (TP) is
urlcoveredtillsfresh mixture is forced through the transfer passages and into
the cyllnder above the piston.
As the piston moves upward frc,
n bottom dead
center {I_DC)it first uncovers the Inlet port lIP) and fresh mlxturo floHs
into tilecrankcas_ as a result ef the increasing crankcase volu{ne. The
piston then covers the TP and finally
the EP and compresses the re_ulnlng
fresh charge in readiness for the next spark |(jnltlon.
Some of ti_efactors Iofh_eecing the overall engine performance are the
ar,ou,tof fresh charge Indl_ctedthrough tileIP, tilear,n,ntof fresh charge
pushed through tileTP, and tileamount of fresh charge that leaks out through
tileEP prior
to EP ciosnreo
These col]slderatlonsorn Mint make the t_o-stroke
engine a nlost interesting dynarrdcsystem. Qualitatively, it is the "inertia" of
the gasses In the intake passage and tran.:ferpassaOe that Insure proper charging
of the combustion Cll_iber,and It is tileexpansion chamber that controls the loss
of fresh charge into the exhaust system.
When the exhaust gassns are forced through tileEP, a large amplitude pressure
wave beglns propagatlng down the e_lloustsystem (see flg. ?J.
As tillswave passes
through
tile
"diverging
,
cone", a negative (or r_|refaction)wave prop,_g_teshack upstream and helps empty the cylinder of exhaust 9asses.
scavenging.
i
i
4
?
When tee press_re wave
reaches the
206
Thls process is called
"stinger", most of
;
i' ",
the energy Is reflected
and Lhls returnls)g pressure wave eiLher pushes
fresh chargeback InLo the cylinderor preventstoofztuch
from leakingaway.
Thls "stuffing"pllenortlenon
of coursedependson engineRPM, exhaustsysteJn
._ '
lengthand variousether systemparar1_eters.
From the point of vie_._
of
perfo_ance,thistype of expansionchambercan providesignIflcanLsuperchargingof theco(r]bL_stlon
chmtlber.Fre(ll
the pointoF viewof noise,the
stralghttllrough-flow
expansionchamberis perhapstileworsL possible
design.
In tilefollowing sectionthe analytlcal_lodellng
of two-strokeengines
and their exhaustsystemsIs describedalong wlth noiseprediction.
/,
207
...............
i
'
_'_-;_.......
_ .............
.. _,,. ............
_.
...... , _-
Analytical
Models fur Performance and tloise Prediction
The model used for performance prediction
Is described in ref,
Since performance is not the main consideration
[5],
here, this model will
not
be describedtn great dotal|, It consistsbaslcallyof a bond graph [8]
model of tilecoIllplete
enginecotg)led
wlth artapproximatenlodelOf the
exhaustsystem. Dynamicconsiderations
includethe Intake,exllaust,
and
transferpassagesas _ve11as crankcasecompressionand combustion, The
aiodelIs Ideal for perforallng
extensiveparametricstudiesof port tlmJng,
port geometry,crankcasevohJme,exhaustsystemdh_)ensions,
etc. The
Operationand capabI11tyof Ulealodelare discussedcomplete)yin ref. E5].
Of more Impartancewlth respectto noise predictionis ti|egas dynamlc
modelingof the exhaustsystem. The gas flow was assumedto be ane-d|menslonal
and time dependent, The equationsof motion describingthls flow are
_-t(pA)- _x(Pt,A)
_a
'
(Contlni,
lty)
dA .
(M_nent_Jm)
i),(.,, . L(u(
DX
Es + PA) )
York
(Energy)
Es . pA(CvT+ U2/2)
p - pRT
where p, p and T are the thenrlodynamlc
propertiespressure,densityand
temperature;tl- the fIuldvelocIty; A- channelarea_ t - time;x - pasltlon; Cv - speclfle.heatat constantvolume; and R the gas constaoC. The
m
frlctionallosseshave been Incl.dedin t#leterm pal where f Is givenby the
_
i,
208
i_ ,
i
followingexpression
F = 4f
D
(f and D are the friction
for solving
factor
u2
2
o
and dtamnter respectively).
the above equations is given In ref.
[1] Hllere all
clrculnstancus such as boundary conditions and internal
The procedure
unusual
choking are discussed.
Foran averagecase, 150 spatialnode points,similarto figure2 vlereused
throughout tileengine and exhaust system and 80D tiilln
steps Here needed to
complete one engine cycle.
As con be surmised from tileabove con_nentsand
equations %11enumerical sii_ulatlon is very cosnplete and general, and capable
of good spatialand time resoluLloe.The spatialand ti_{le
resolutionis
extre_ly i_}portant
for makingnoise predictionssince highfrequencyHaves and
largesound speedsare con_onIn tHe-strokeengines.
The model Is capable of predicting pressure, flm_s, temperature, etc.
througho;&t
the entireexhaustsystem; believer,
for ti_epurposeof tIHs paper
onlyresultsassociatedHiLh the "stinger"Hill be presented(see figure2).
Also,all resultsare for a Yamaila
360 HX engine.
Figure3 shows tl)epredictedvolunle
f|oH ratefrom the "stinger"intotile
alm0spherefor the engineoperatingat full throttle,under load,at 7000 RPM.
This Is approximately the maxilnumpower lIPI4for the 3GO cc engine.
The steep
frontedwavein th_ cRnterof the figureis the d_inant cause of ti_every
loud, highfreqiiency
snap associatedHlth tHe-strokeengines. Thls In also
apparent from figure 4 Hhern pressure and velocity inside the stinger section
are shown,
Pressure in excess of the atmospheres is predicted vdth velocity
surgesin excessof 450 m/s. If _e assu_ that any realisticmuffiingdevice
will net change the engine pnrfor_lance too nu_ch, thon _e see that extremely
large_plltude, high frequencyHaves _dll exist at the rlluffler
entrance.
209
,_,
This suggests that
for
accurate
the type of nonlinear modellng presented llnr'e Is essentla]
prediction
of muffler
perFor1_ance for
small,
high perfomance
power plants.
To predictexhaustnoise levelsfor this engine,tilevolumevelocityof
figure3 wasassumed to be thatof a simplesourceradiatingintoan anechoic
for field, Tile
pressurepredictedat 50 feet from tilesourcewas digitally
transfonlled
Intoa frequencyspectru_il
and is shovlnin figure5, An A-welghted
sol_n(l
scalewasassumed. A significantcharacteristic
of the spectrumis that
it is relatively
flat and containsa broad i_andof frequencies,Also, there
Is very substantialcontributionfrom frequenciesover fOODcyclesper second.
The total SPL,weightedfor tileA scale,that Is associatedwith the spectrum
is 102,85dh for50 feel from tilesimplesource. This nulnber
Is in good
agreementwithSPL measurementson unmuffledexpansionchambers.
The ne_tresults to be presentedare concernedwith the additionof
m_4fflers
to theexhausts.ystem,In fl9ure6 is shown tilegeometryof two
mufflersanalyze_l.The nonllnearmufflershown In the Lop of"figure6 was
analyzedwlththe new methodsm(!nLioned
previously,while the lumpedparameter
mufflerwas analyzedwith classicalacousticaltype approximations.In flBure
7 the volumeflow rate out of the nonlinearm,ffler is shown, It can easllybe
seen by comparing
with figure3 for theL_nmuffled
case that conslderab]e
smoothingha_occurreddue to the muffler. IIowever,
there is a very distinct
and regularhighfreqwencyvariationin the flow. This regularvariationis
due to the reflectionand formationof w_ves in tilemuffleritself,and the
frequencyis characteristic
of the mufflerdlmenslensand gas sound speed. Tllls
frequencyend itsharmonies are very evidentin the sound ._quara
spectri_m
shown
J_
in figure 8. It Is also apparentfrom the spectrumthat frequenciesbelow
1000 cycleslsecand very high frequencies
have been suhatantlally
attenuated.
210
k
i:
.,t.,F:_,ii_:
:_;_::::,,_
:,:,,.. :r;,
e,
L
I!"!
!! , ,_:
_'*.
•
i
The overall
SPL for the nonlinear
unmuffled case, but still
muffler
Is 95.8, whlch is less than the
not very llveable.
One of the primary reasons for solving the lumped parameter muflqer
was to comparewith the nonlinear case and to nlake an asessmeot of the
quantitative
value of standard ocoustlcal
of the lumpedl)arameter muffler
monllnear
approximations.
In the modellng
the system Is represented by two volumes, two
resistances and two Inertias
and this system Is solved siimAItanoously
with the flow In the engine and expansion chamber. The volume flow rate from
'the lumped parameter mnffler
smooth.
is shown in figure
The spectrum shown in figure lO illustrates
been auppressell by the lumped parameter muffler
the dimensions
it
g and it
of the nonlinear
is seen to be extremely
that all frequencies have
and tile SPL was 58.9db.
and lumped parameter
muffler
Since
are very similar
must be concluded that tlm use of the lumped parameter analysis
for tile
large amplltudes waves In two stroke engines is questionable.The one region
of the spectrnm where there Is qualitative
agreement between tile two mufflers
is in the low freqweney part of the spectruta.
Another important Interaction
between the m_ffler
and e_haust system tbat
shouldbe mentionedis tileInfh*enceof back pressurecat{sod
by Frictional
losseson the transferof BassesIn:o and out of tileenginecylinder. For both
the mufflersanalyzedthere was enoughback pressureto cause a significant
omounb of exhaust9asses_o be left behindin tileenglnecylinder.
The mufflersanalyzedhere are quite prlmltive; however,the new technique
employedrevealssome interestingphysicalprocesseswhich are not Includedin
classicalapproachesto tilesubject. The shnplesource assumptionused to converb
o_It volume flowrate Into a SPL predictionprovedto be qnlte accuratel_hen
comparedto actualdrIve-hytes:s {seeref. E4]). Furtherdevelopmentof tile
nonlinear,_nml)'sis
discussedhere seems to offer the hope of gafningconsiderably
greater Insl@htinto thenonlinearphysicalprocessesin mufflersand two-stroke
211
I
engfneexpansionchambers.
TJ_m.
Expe_ram
Coupled closely
to Lhe analytical
effort,
tile expertmenta!
program was
deslg_edto firstcorroborate,in so fat"as possible,the computermodels
developedfur performanceand noise prediction. Ti_Isaspectof"the program
is discussedthoroughlyin refs.[3], [41. [5], [ill,and [71. At thistlrue
thls corroborative
experfi[ieotatien
Is not directlyapplicableto (nuFfIer
evaluatlonand wlH not l)ediscussedFurther.
Anotheraspectof theexperlrl_l_tal
in'ogram
v#asthe designof procedures
nnd devices forevaioatlngmufflersIn the Universityof CalJfornla,0avls
anechoicfacIHty. The mahl purposeof theseexperiments_YasCo lest muffler
modelsdesignedFromacm_stlcconsiderations
and to comparemufflerdevices
subjectto reaHstlc largear,pIlt,de
Inputs. Two e_perlmentalapparatus
iYere developed,
These are described next
,r
!y ,
• "
_.:_!}
_12
:_
,
--
Acoustic Filter
':
".._.
Apparatus
'The ncousttc filter
apparatus wa_ designed to test mufflers subject to
small omplltode vo],me flow inputs.
ftgL_re 11 and pictorially
in figure
This device is shown schematically
12.
in
L_asica]ly It consists of a high
|mpedanocelectromagnetic
shaker{,rlvlng
a pistonand tIHs producinga known
frequencydependentflow so_Jrce.As shGi_nh} figures11 and 12, the shaker
andpistonare enclosedin a thick wallpipe to preventacousticleakage.
Tile
devicecould be modifiedto includemean f}owbut at this time no mean
flowis available. This device is perfectfor measuringinsertionloss of
mufflingschemes; however,it Is restrlctpdto smnl] amplltodeInp_tand
correlation
wlth actualmufflerperformanceIs qnestionable.
r
n
21:3
LargeAmp11tudeSimulatorApparatus
In order to use tileanechoicfacflltyto testmufflerssubjectto
realisticinput,tileapparatusof figures13 and 14 Has developed. It
colislsts
of a high pressuresupplyto a ulenumcbamber_hich feedsone
side of a rotatingcyllnderdrivenby a 1/15 horsepowerelectricmotor
The insidecylinderhas a port Hhictln11o_scharging_ith highpressure
alr as tileport rotatespast the plenumopenlngand then subseqaentdischarging as the port uncoverstheexhaustopening. This simpledevice,
Hhen connectedto a stock Yamaha360 MX expansionchamberprodL4ces
pressure spectrawhich are virt_allYidenticalto that sho_n in fiflure
S.
.Thusfar, the rotaryvalve has been used for qualitativecBnparlson
studlesof variousmufflingschemesand has provenI00% effectiveHltb
respectto comparisonnoise studiesof actualmotorcycletests.It was
not attemptedhe duplicatequantitative
resultsas thls was not essential
for the Yamahaproject, ilowever,
thereis no fultdamental
reasonwhy the
rotaryvalve could not be u._edto producequantitativecomp'arlsons
of
anechoicchamberversusactualmotorcycletests. It appears thatattention
need only be glven to exhaustpLilse
ampllttJde,
volumethre_Jgh-pL_t,
and
gas temperaturein order to obtainquantitatlve
comparisons.
The questionof perfomance degradationassociatedwith variousmuffling
devices is not as eas_,to inferfr_, the bench tests as was the noise comparisons, Again,however,it appearsthat if some attentionis given to
this speclficproblem,ther_ Is no fnndamentalreasonwhy correlationcannot
be obtalned.
i +
214
_+ _,
_.*_, _.'I, _', _I ,-,
4,.
,, , _
._
D_s
a bench test procedure exlst For certlfylng motorcycle exhaust systeln
performance _|th
respect to noise and performance constraints?
At the present thneo such a procedure does not exlst.
IIo_ever,
it is
felt that rotary valve is a candidate For devOlopnlentInto a dependable,
Inexpen_tve, and Fast procedure for evaluating, at the very least, twostroke englnes for motorcycles and snowmobiles.
It is also anticipated
that _mall, four-stroke poHer plants can be tested In a slmllar fashlon.
Nhat Is required Is a research effort directed speciflcal]y at tilecertlflcatlon Issue and relylog heavily on the research results already
developed.
t
215
i
L|st of Figures
.'"
L
Fig. I
Schematicof:a bye-strokeenglne.
Fig. 2
Conventlona}expansionchafl_ber.
Fig. 3
PredictedVOIUR_L'
FTO_Vrate from "stinger"
of unmuffled360 MX at 7000RPM.
flg. 4.
Predictedpressureand velocltyInside
ti|e"stinger"foruuI_luffied
360 HS at
lO00 RPH.
Fig. 5.
Prossnresqu_redfrequencyspectrumn
rest_Itlng
from Fig. 3.
Fig. 6.
Mufflergeometries.
flg. 7.
Exlt volume flowrate for tileoonllnear
inuffler.
Fig. 8.
Pressuresquaredspectru{n
res_dtlng
from the flow of Fig. 7.
Fig. g.
Exit volumeflow rate for tltelumped
paraR_.ter
mLffflor.
Fig.IO,
Pressuresquaredspectrumfor volume
firthof Fig. g.
F#g, II,
Schematicof the acousticfilterapparatus.
Flg. 12.
The acoustic f11ter apparatus set-up In
the anechoicchamber.
flg. 13.
Schematicof rotar},
valve.
flg, i4.
Rntar},
valve set-upIn the Anechoic
fact1 IV.
--
--
References
[1]
Owyer, I1., Allen, R., Ward, t4., Karnopp, D., and
Margolis, D., "Shock Capturh_g Finite Difference
'Methodsfor UnsteadyGas Transfer",AIAA Paper rdo.
74-521, AIAA 7th Fluid and Plasma Dynamics Conference,
Polo Alto, CA.,June, ]974.
[2]
Karnopp,D., Reed, J., and Margolls,R., "Design
and Testingof Reactiver.lufflers",
Proc.of tile
1974 Internatlona]
Conferenceon Noise Control
Engineering,InstiLuteof Woise ControlEng.,
pp. 325-330.
[3]
Karnopp,D., Reed,d., Hargolls,D., and l_.tyer,
II.,
"Computer-Aided Design of Aconstic Filters slag
Bond Graphs",Noise ControlEngineering,Vol. 4,
No. 3, May, 1975.
[4]
Karnopp,D.C., Dwyer,II.,and Margolls,D.L.,
"ComputerPredictionof Puwur'_nd _lulseforTwoStrokeEngineswith Pc_er-Tuned,SIIenceExhausts",
SA£ Paper150108,August, ]975.
[5]
MargoIls,D.L., "Modelingof Two-StrokeInternal
Combustion EngineDynamicsUsing the l]ond
Graph
Technique",SAETronsactlon,Sopterllber,
1975,
pp. 2263-2275.
[6]
Kelsay,R.E,, andMargolls,D.t., "An E_perlnlental
Investtg_tlonof Two-StrokeInternalCombustionEngine
Perfor_ence",SAETransaction,1975, Pl).225]-22(}2.
[73
Osprln9,M., Karnopp,O., and Margolls,D.L., "Co_nparlson
of ComputerPredlctionsand £xperhnentalTests for TwoStroke £nglneExhaustSystems",SAE Paper 750172',
februar},,
.1976.
[8_]
Kornopp,D.C., and Rosenberg,R.C., _,jnt_m
_.in_nf(_:
A I/t_ft_d
Appro_oh_John Wiley and Sons,Row York, 1975.
f
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AL_IIIAt_
ViLrlousprocedurc'J for tileovahlattoa of exJlallat
systcI[l
perfolIi;ince
are
predated
and dlsctmsed.
considered.
oolge.
Analytical as _11 lu_experilmotal techniques are
Co_q],_risons
The nnjor
,_re fm_de with
approaches
Imasur(]nonts
lu'e rmiRod
with
on actuld
respect
engllle
to accuracy
exh:tt_;t
and cost.
Im'K)DUOPIC_"t
Ill
system
OIXlor
select
to
performance,
an
the
TNo needs
of the
tcchnic_l
COll_l_]I',
ilppl'opl']Rte
t,]meific
dovelolm|ent
'Ihis
techflique
goals
engineer
of
for
evaluation
tile
tile CVlllllat_on
m'e quite
or e.xham;t
different
llRISt be determined.
tiara those
p_tp_r will attcllq)t
to pl_sellt
tile
of
the nen-
VIUPIOUtleollsldnl'lttiell8
preheat Illr_tklllg
such Itselection and to illtv*tratca wide vltrictyof available
tccbnlqucm
_mro
are
essentially
no "6Qod"
or "bill|"
l[Rlfflel'l].
A given
Imlffler
_y
produce p;ocxlnoise control rcsulttlon a given sy:itcYn
or appllclttiont_ilc |ll_odaclng
poor re_llts for another,
l||'nddltlen,many _ecoadary paratrctcrstoilet
be in-
cluded in order to fully characterize the Ferfon_mce of a given r_fffler, a
_nmu'y
Of scxm lxmlc dcslgn considerations is gtvea in Fig. i,
_l _w,curat_
statement
of
the
_lffler':l
l_rfonmmce,
it
2la_],to obtain
in nccc:)t_ary
to specify
the pre.ctsoc_haust t_yst_ configuration and cngloe application including
operating
coadltlon:_
Two of
,_uch as .speed ned load.
th_ prirmry aco_mtlc conside,
rations are vd_thcr to rm_uro
_d
pressur_ or sotmd porterand _hother to ltscthe actual level produced or the
dlfferenc_ b_tween th(_silenced and tmsllencecllevels, A "dlffcreoco approach"
has
of
the
advantage
the nois_
lating
loudness.
more
courco
directly
of
relating
more
involved,
whilu
to
directly
a "lcvol
tim _olmd pc,rc_lvcd
to the r_lfflcr
approach"
by thc
b_
listcner
l_rforlm_co
lndcpcndcnt
the advantago
and _msociatcd
of re-
_llo ¢holce bet_zen mound pressure
_s e_mcntlally
lL "_oint mcn_Jur__at" ver_t(_an "lu'eainoa_ir_aont".
b_t_en
certain ndvantnge_,
po_r
level
the e_llnnut
nppr'oacb
|I;L_
a location Imy be clearly detezlnined. Sound
frc[n a n_2;murccncnt
l'J detellni_lcd
ltrea and,
Each
a choice
_ounO pre_.'mrelevel nlu._L
be given lot a _peclfled location
and is nm_t appl_prlate Id_enmmh
over
and mound pol_r
of
thLL_, n_y be iiDro apln_prlate
the
uhen
average
the
sysLcrn in not clelu'lydeLe_lulncd, _
_und
location
pres_.ax_
Ileal'
of pertness
of the practical
level
CellSid(_rlIt_on_
in _Lklng the_e ;leauuronent_wlll be pre_ented later.
I.
_ALUA'rIC_N'IIr.CI_IQUF_
h flow
le
sh_n
chart
in Fig,
be discussed
engine
tco_pcraturu
variations
2.
gradients,
of
of
otud¥.
preferred
!
the
3.
engine
techniques
and exporinxmLal
nppl_aehcu
varying
_ffcttt)
teclmiques
following
are
reason,
technique
flow,
hlv)l
mavng the primary
actual
tu'c
aw_llable
lit_ted
and will
of
factor_
_yatcm
system
designer
an actual
difficult,
n_qplitudo
(,zhal_nt
tim e_haust
nre
21_o cogole_ty
o_ a rzlngle
turbulent
most
to as:d._t
ucctlotm,
that
F_vere
in_J_._uro
c_ntrlbutlng
to
engineering
u._,a
a
in obtaining
p_rfornmnco,
specifying
becau._
evaluation
t_Jleetlon
rapidly
For thl_
A 'wld_variety
Flg.
major
in tbe
rmd_o_ tile
_vstcIn
cooplnxity,
optimum
Analy_icnl
ned non-linear
coubination
ol' the
in more detail
c_dmtmt
thlp
of "Jo_
of paramoter._
e;dlnlmt
In general,
it
sy_tcrn
not depend
_aurc_
inOc_mce
For e.xpe.rlmo_tnl
be_
of their
available
perfor_lco
transmi_-_lon
does
are
loss
on the
c_glno
l_ a difficult
_orJ_,
Insertion
relative
case
for
(1-3),
la
preferred
i_so by the designer
Sc_r_ of
for
theoretical
r_ourco trr_.danco.
problon
that
los:_ a_d noise
of
ttm._o are
_lo
has
listed
in
calculations
d_tcrminatton
me.ceived
reduction
in
only
limited
have cc_o
to be
determination.
235
'
l
The method of excitation
treed varies l'rc4nthe actual cnglne to a Mtitc
noise ,c_urcc. lYhlle_llzltc
noise lainbeen recompendcd in the p_mt as a _;olutlon
to
the
problan
of iT_a_urlng
thL']can b_ inadequate.
or
cpttlnlstlc
Dotlrc.o,
has
tuned
of
n nmfl'ler's
pm'fotll_mce
n_fffler_
depending
exhilllst" _yotcln,llnd _-It_ureII)_llt
pl_:x_efiltrc
IL';ed,
con_Jlderablc
onlmant_t_tc_m
past
study
and has
u.qed on hlgh-perfolllmnce
(4),
In fact,
specific
on the
specific
S|IOC}_
%_iveexcitation
advnntage'J
hit evaluating
cngine_.(5,{])
ANALYI'IOAL2TLTINIQUES
Analytical
o_t
of
Tplcx
udo
tcc|mique_
e_perin_ntal
chntquc'J
_tlch
i_ ||in
acou_tic
been
model
cxmsiderably
variety
w_.th actual
to obtain
improved
predicted
transmisnlon
_0
of
a half
I_
P'.,;I
Is
wavnlength,
cx_lexity,
all
extended
very
correlation,
"2_fleal
plot
to tim length
of
/_dditional
to tho
The predicted
of
Innertion
duo to the
ngrc(_mnt
minima
with
.silencing
¢_afi_lwatlon_
thi:]
claantttatlvo
about
ntudy
6,
tbo tnilpip_
effect
plot
of
tho engine
2.]6
at
about
equalling
e_|aust
n_n.'az_
_o
a maltlplo
ilh_trates
the
in croat
,125 lk% 850 ]l_ and
nr_ present
lc.sn
znodol hat_
in a wider
continued
at
of
Impedance,
chnmbx_r equalling
minima
length
effect8
nr_ vahova_ in Fig.
tho expansion
ncc_ondary
the
(10-13),
andergoing
st_wm r_.Jor
1_ quite
tmTatnation
of
to
to npply.
lncludco
ntnndpoint,
rc::;ult,_
nanlynln
technique
to Ix] iq)plicablo
:from a de,'lign
ia
parlllnOtrtc
otnplo
nnd _ivlen
Nelson
or
Jn 1'1_,,_. 4 and 5,
_|IC_YII
mean flow,
at
tile ti_o
r
nnci _t wide variety
racanar_ncnt
in gned quantitative,
l'rOnl _lli_lo
althonlih
gradienta,
tmcful
pa_vtially
requiring
and lme¢l at Nelson
nnglno
lo_s
not
tile paralpetcr
modelling
m_le_b
nod
and so oa corresponding
a half
lnerea._ed
_ntwlength.
voltUl_,
from wDrk by Alfrn(tv_on
Although
agreement
of
order
of
rtulgc
In gcnnral,
developed
improved
of ea.'_en,
eo on corresponding
n_lfflor
tcmpe.rature
l)_rived
advantage
They can
(7-9)
l_pedanco_ higher
elements,
the
to nsou_tic
tcT_dratu_a,
_urc(_
or
n_e of
model'J.
in comparison
dovated
offer
proccdurea.
The acoustic
*
of highly
A uhlte noise _om'ce callproduce consezwatlve
pz'edictlon'n
received
II.
tile perfotl_mce
150 I_,
a _ltlplc
r_me_hat
ptpo,
insertion
Noithcr
1o:_%
!:
r
l,
I_ItJlot]_ll
t|lefFet]tloIIcy
ehrLraetel'Jstles_h_v ._m_ qua]ItatJvf::q,_recliz,nt
toldlhc_
amplitade.q
reflect
cG_putcP
model
5nine general
hm'_ been
trend.q,
_amccwafully
l'vcn with
utilized
these
limltationf;,
in a ntmd_cr of
thh_
co]l[_rcial
de.,_i_,j_
activities.
._PI_lI _Pa_TAL '1.I_]INIQUES
IIl.
Faff_rilmatal
open
t_yuttml tcchniqueu,
Clo,_cd
sy:lton
Imlfflcr
tJhell
in
the
ttsing
or enlzaimt
irrTmdanc_
a white
tutra.
from
eurvea
1,_ wry
inlet
good
pul'o
tone
listener
ohown
_lalu
the
or
teehnlque-q
do not
include
the
piping.
radiation
find nneehoic
lined
re:mltn
or valitn
the
mcxlel.
or
tile
in tho
L_ rr_d0 tk_lng
x_tl Is of
exm:ple
thlr_ device
tlhu_trat;ed
obtained
Ill tlil'd
lit about
taFa,_d engine
a sy._:tc_n
lo.';s
be ILqed
in considerably
In
I'lL.
u_;lng
exa_l}lu,
300 lla,
7.
the
of :inch
ella al,_
life obtained
_tre aPln'Oxiir_itely
pestk;]
the
'H_o af_x2¢_nent lx2t_een
re:a-altn
llOl_e, tiOUl'Ce.
p,a.s,_ =lfIler
from
nnd
in Fig.
l,o nrJia_;ure trm|,'_nh_'alon
tel_lllllation,
ta_/liilltl'
of dosed
lu'e illu,'_trated
'lqle .t_-_;t ecmton
Typlelilly
Very
catel,,ories
equal
the
thhl
tile
to
B lllotlg
with
top tile
technique
_olld
half
extended
the
lenlr.th
900 llz, and _o on.
noL'ie anti other terminations;
It.']
later,
i._edanco tnlx; n_ly al_o Im t_';ell in the tln_
teebmiquo.
advantag_
'Milch
hun recclvt:d
of presenting
and tz,_ a_sociated
with
the
the
consJdernbl(l
pres.'_ure
engine,
_wr, fonn
in the, tJn_
d_gdn
im a "pult;e
tlevolol_IL'nt
al: Rely, on,
tt.n perceived
domain.
Ilc:mltt_
by tile
will
be.
below.
Open _te_n
_lls
these
analytical
re'aulting
_1o closed
offer_
of
rind typical
of
muffler
Im shown
tuh_",
k wu'lcty
_lxx11.qllch nl2IISlll'Cllmnt_J ltl'e
ItEm=a'urermnt_ may a]_o
will
t_lo general
(14-16)
the, Nelson
and outlet
tim
the
systc_n
_ource
Rcsult_
reSulta
the
into
notr, o _ourco.
le_-_ time..
with
fall
muea_urc_entn
a pure tone
with
of
techniques
mea_ure_ntn
by term_atlng
reverherant
_r.
the
lncluclo
tntmOanc/a
_e
the
nellie,
radiated
finn
zmtfflt,,r
nnd tailplpe
tutx_ in nn olx,'n _qmce ._nch tel It ta:ml~aneehole
excitation
muy be typically
237
nn eleetPonle
noi,_;e
i
i
c,ouree,
blotmr,
stand;Lrdized
0nglno,
¢3111mbor5 ,'I_d It rovez'l_)l°aNt
Im shoxm in
utilized
Figs.
,5OUlld
COl°rellltloll
9 and 10. (17)
chaJ]_l'
for
the
without
n_icle
0_ll:door.';
on actual
of
tile
spatially
may L_] readily
lr_,_l|JCC11_llt
potentiul
chall_)oI'
for
sound
ILl;
xt_athel + In'obh_It_
pre,_mure
level
Far applicationu
llpDltl'ellt
_n that
the
At Ncl._on,
J
the
average
ft_n
in _tllch
revttl'bori¢llt
value
tt_e
_Cm[-IUIC'dlO_C
tL_,e ill _llch IlI2aStlrew_.nts
cha,_>er is
pl'Jg[tl'_'
wi/h
_dlich
the
l_)cl_
the nDst widely
adv;ultago
i_
its
/])2;ISIII'L_IIJB[_
_']IOreverb_l'antchlm_r
equII_l_llt.
Feadl]y
|_dvllntage
are avai hlb]e
ev_lhl;tti()ll.
its.nocinted
avernged
llO_
enghm.
The .';[+nJ-;mechoic
/ii[l[i'lel"
calculated.
it3
or actual
:dlow'd_2[tsur_]_llt
tile t3OtllKl pO_'Of level
desired
point
II_[|.';UEL_I_2Dt
h_ obtained,
lknmver,
of
provides
if
a
tile me[sure-
rncnt Jn the .ncml-_mecholechnI_Lc,
r is sln_ly ii_ule
at tllcimgle of m_u'dn_n_ound
prestln_'elevel, tillsl%dvant;Ige
is minimized ,'Hncutile'o]_i_tlf_l
avornge will Ix.,
fitDo.glydcxnin;%tedby this n_t_Inaun
vldue. 'l_itlS,
for ll_iffler
%of'k,the ._dn
,dvt_ntngesof the rcwcrlxn'imtchnIi_mrl_c:_r_
fh_xlbillty In e_chau:_t
nylitt_l
plplllg
gl_ter
In_lirl_ODllllCe
IV.
A,
Its literof llBoc]lolc
B_JÂl_,q.'t_,
allo_vlng
BII(i
It dl}(.'re_l}}e
I[I_nstalli%tlonand
e_p_:Bt;e.
OCtlPAIIIt_ON
OF 'ITL'I_IQUFS
BASIC SI[I';NCIHG
]{ll@_f
Ti_e l_rfon_mce
of a b_l,'de
e_p_m._Ioll
cha[]_r .'][lcxlelng
el(.cncnt
w_s cv_duatcd
Using I_val'letyof the nbovc tcc|miquu_l. In Fig. Ii, rcmllt,'_
u:iing the nnl_lytlcal
model wlth an nnecholc t(:llr)ll)l_t_on
I_n(l
free-fleld te*_nIImtlonere centered to
results n_asun:d on tileJmDcdance tulx:duvelol_'dat t{el_nil._]Ioe,'cplmulon
ch_rt)r:r
and tailpipe.,
effects I_:_
vatllIm I;11o
hli,,her
order .rideeffects (I_L iflxmt2800 l'Iz)
lute
predicted with ftdr nccur;_cy,,::,pcclally
lop Lilt} nnecbolc t(:nnlnationen._, by
:
the analytical r_)del,
In l"l_. 12, r_sulLs for the mur_)unit using tilel*nalyLlc_lmodel wlth an
anecl_le temlnatlon,
_,
[
source
_n_w.'dtu)ce effects
tallpllx:
, _*xld
tullpllx,/exhm_t
tn obtt_ln
insortJon
ccmi_InIltlen
Ineludlng
lo;_s nrd cc_pared
238
i
plpo
to
results
mc,m'_urcd.
interference
leveba
to
effectr{
due to
_t_re reduced
83 ¢lLt_ for
tl_e lntalce
excitatIoll
ellgllle
noted,
for
the
noise
and ft_n
of a typical
with
a._ shown
reflect
lore;.
The ovcrttll
f]'c_l 117 dl_ to 99 dl?a for
'l]le perfol_r_mce
nolle
floor
17.
tube
The lack
noit3e
119 dRA to 91 tlI_for
tlalck muffler
th{_ ln_2(lantze
in Pig.
tile uhite
alld
tile exhaust
of detailed
_lound level:}
_llte
source
from 111 dBA to 7.'!.dllA for
and
using
reduced
frc_n 100 dBh
is
fron
noise,
a'hite
all actual
fr_ll
correlation
_ure
:;ource.
lloiso
g-v,ulghted
l_ound
tile exhaust
_m-'_evaluated
q]Je overall
noi:;e
A-s_ulghted
again
readily
115 dl]A to 7fl dllh
the
engine
lloise.
Other detailed _,tudie:l
at Nel_J_lhave dtan3nstratedthe dci_ndence of
o_hau};t
lloL'io on exhau_;t
overall
A-_mlghtcd
_affler.
can
".Jound level
_]lil_ again
a given
uy_tctn
In addition,
l,e an Int)ortant
varlablu
conulderably
i_l_lly
chamber,
thin
pres._awe
level,
the
directivlty
pattern
of
angle
19.
18.
the
frown an c_hannt
'llm bhal x} of the
£rc_n the outlet.
In I|volded
_lgJIlll_ll
pret;,_nl_
F,olllld
IN obtaining
Ot c.olm'_% dlrcetlvlty
a t;patlal
tnfomntlen
The
the
same
application
for
outlet
llF,cctra
/l_ dlscu._ed
clll_/lt_2r, tile IN?ll:itlrC_II2nt location
on tile llaal,_t of
(20)
as ffllch it:3 7 d_ fop
of t_pcclfylng
au _llo_m In Fig.
a,';
a fanctloa
problem
ln_ortallce
the
prev/ollsly, In _t F.oqll-ii_tlcholc
._oleeted,
tm t_ho_al In Fig.
Call be t_et:n to wu'y
cnl_hra_izca
nafffler.
Vittles
conflgnn'atlon
nalstIx} ean._fally
level.
average
in last
In a revertmrant
of tim
ill tmch
round
a ._oulld l_r
_ea_qu ITlr_t.
V,
SIJI_IAI1y
_leetlon
goals
of
above
have Ix;ca
cost.
It
the
of
evaluation
ranked
is clear
can be _loctetl,
that
an evalnatloa
technique
pll_l:dtlre.
according
Ill Fig.
to the
many tradeoffs
hlthough
various
n_it
20,
prln_try
ralst
'i
_l,|or
npl)roacbe.'_
on the
teelaltques
characteristics
lx,_ conaidcPcd
240
!
the
lx_ |_tned
_,]melfle=
desertl_t_l
of accuracy
I_.'.tom
can be I_¢zafal nudnly
a given
for
and
teclultqne
dc_slgll
]_i_l_(_es;flnal f_]cr
Only
in this
way c_In tile
¢}vi_lu_Llon
utm:dly {[_mnd_ _m acLtml cnglno Lo_;L
rcqulrcd
accuracy
be achlcvcd
(21).
Erroru
of 5-10
dB
:hi Inuffla
F perfol_r_incu
prcdlctlon, oftcn cnc_)untcl'cd
Jn other technlquc_J,arc
:(: :"(:"
_,t ,,_¢_t,,hler0,. to_,,_y._
_,,,,,1,,:,_tlo,,
v,_l_,_;.
The a{;.si_tancc
of Dr, Ivan _loz'se
of the Unlvert;ityof Clnchmatl
the
tr/lil,_f_P
Jn provldlng
fUlICLJO_In_?_l_UF_X211t,_;Hzld D, O]t_o[l, D. l"]_inclcl't9, [(. ]|ooi}._, /tllCl
G, Goplcn of }/el,';on
in pl_]vlding_upplcI1_ntal'y
data 2_]C,,ratcfully
nc/molvlcdgcd.
!
I
5
g41
PJ_q_ENCF_
1)
Don O. Daviu,
Jr.,
"Handbook of Noise Contl_l",
Jr. (cd).
New York: t.icOra_v-llill,
1957, Cilaptcr
C. M. liarris,
21, p. 21-5.
2) T. F. Y_.i_I_)letoIL"Noi_;eand Vibration tbntrol", Lc_ L. L_r;mek, (ed.).
N(_vYork:',_IcOraw-l|lll,
1971, Chnpter 12, pp. 363~3G.I.
3)
Nor|r_inDo_lllng, "Noise Reduction", _
L. 13cranek,(cd,). New York:
_cGl'aw-lllll,
1960, Chapter
17, pp. 435_-|37.
4)
Irwin J. Schv_mher,
Cecil n, Sparks,
and Dougln_ J.
Test Facility
for Engine blufflcr
E_aluation."
Paper
_t _AE National
Powcrplant
r,iceting_ Chicago,
OctoL_r,
5)
B. _turtewmt,
"Invc._tlgation
of Finite
hlplitude
at Interag_ncy
Syml)osit_n on Univcr:_ity
l_esc,_rch
_lareh 28-30, 1973, 8tlufford,C_llfol'aia.
6)
B. Sturtevant, "nelatlonshlp Det_en 'l_¢hi_unt
lqolscand Po_r Output of
_all
lligh-Pcrfon|_ance
lnto_nml
Cc_u_tion
Engines",
Final
l_eport to Neluon
Ind_n¢_les,
Janua_'y,
1975.
7)
L, J_ E_'il_n,
Pl_,nted
at
[I)
"_ffler
_lsconsln.
9)
Z'vich K. Dender and Anthony
,l. Ilrr_,
and E_hmmt
System h_l_)",
J. Acol_t.
10)
/
/
51dnner,
"h l_nch
771A Prcuentcd
1963.
_ound Wavcu",
in T_'an_portation
"L'_Jm_mt _y_t_a_ for lllgh-l_erl'on_mce,
_lol.,_c--Con 73, IVnshlngton,
Octol_:l',
1973.
Design
Guide,"
Robin J. Alfred_n,
Ph. D. Theals,
Inat,
l_ll_tin
No.
74500,
Ncl_on
'Inte_mal
,_oc. 5_n. _
'_llm Deulgn and _)timt:'_tlon
Dermal and rib.
II¢._., Univ.
Four-Stl_kc
_lufflcr,
Pl'e_cntcd
Noise,
Enginen,"
Stou_,hton,
Cc_nlmu'_tion I_nginu
(1)" 22-30 (1975).
Intake
of lrmhatmt _llcncer:L"
of _utlltmpton,
July,
anti I t. O. A, L. Darien,
"Pcrfor_umt_
_tmd
rib.
1,5 (2), 175-1_1 (1971).
of
I_m_t
1970.
ll)
a.J.
Alfred._n
(3_cnta",
J.
Silencer
12)
Tony L. Pa_rott,
'!ha lmprow,_ _tl_d
for De._;lgn of lbq_anaion-O)amber
Muf£1_rs with _pplicatlon
to nn 0i_r#ttional
llellcoptcr",
NASA Technical
l_tu _ D-7:_J,
_?nnhington,
October°
197'J.
13)
Joh_ E, _n_O_cnb_.l_ger,
"_cccat
II_:n_lt_ To_mrd F_l_rln_:ntal
and Analytical
_letion._
of II_le
I¢_glnc l..'aha:mt Sy;_t(_m lk.,rfonmmce
- Part II - _
Prc41res_i_ Cx_put_r-hlded
I_.'.'_lg_l for _lnly.niu
and Optinllz:ttl_n
of Pk_slc
_'bthaust System."
Prc._cntcd
at the.' Eighth A:m_al N_i_
Control
in Inte_al
(k_tion
_ngineu
Sc_ninar, Uaivcr_lty
of Wl:_consin,
_dl:)on,
Janu_try,
197[L
III_I,'I_II-_CES
(Cant,)
Id)
Don D. l)avi,%Jr.. et. al., '9_icoretlcaland Ex.ncri*_ntalInve_tigatlon of
_lufflcr_with Comments on l_iglnelixhm_t Muf/'IcrD_.qlbm." N/ICAlleport1192,
09_I).
15)
I)o11
D. Davis, Jr., "Nandbook of Noise Control", C. H. lhu'rls,Jr. (ed.).
Now York: McGl'm_-/|lll,
1957, Chaptep 21, p. 21-_13.
16)
D. C. Flanders, "Recent IlemHts To_mrd I_I_rin_ntal toldAnalytical Prcdlctlom_
Of
1341tileEIII,.IIIO
LaNhlRIst
Syston
Pcrl'ol1_lllCe
- Pal't
I -
II._Icd:|nce Tube:
A
2bol for tile]IOSOIII'Rh filialLk:vc]ol_II211t of [Ill,lie_IUff]eÂ' Elc¢l_I|to."
Prcsol|ted
at tileEighth AllllUld
Noise ContDDl tl1 Internal Cc_i_)ustlOll
]_llgllle_]_1111nttl',
I_|lvcr:;lt],
of IYlsconsln,
_ldl,_on,
,Jlloui|l'y, . 1970.
17)' _, J, }'rJlLg.9Oll,
"IllllovIItive
Approaches to l','nglne
}lois(:
,_len-'mrc_r_nt."
Prt2u(_llt(.'d
at the Eighth /_ntnml Noise Control
In Intcmml
Cx.xllbtl_tlon l':ngilles3 _qc_alilttl',
[hltv(:r:_lty
of IYlseonsin,
i',ladl,_,un,
J_lntlary,
1976.
18)
l)iIta
provided by Dr. IvllnMorse, UIllver_Ityof Cincinnati, Cincinnati, Ohio.
19)
P. A, Ol_on, D, C. Flander-'%and b. J. Erlk:_soiÂ,
"An Integrated Approach to
_dlau.'it and Intnke Noi-._o."
Pal)or 760602 pl'ct3ellted
lit _qAE I','o.';t Col|St}.looting,
San l"l'anclflco,
/hll_t, 197(I and 8AE Ol'f-lIlghm_y
_lL'etinb',
_llhmukce, &_'ptc_laxJr,
197(1.
RO)
D, A, 01_I|, K. D, }brdlle, and _. d. Sell,i,"ru,
chnlqucn and Problcm-_of
Tl'llck }_'_hau.st _y_itcrn Nol:_e t.lc'lu_lr(_tI2ilt."
Pal;er 7708.95 prc:;entcd
at BAI']
Truck _I_ting, ClevolIuld,C_toL_r,
1977.
21)
L, d. ErlP_._,on, "Dl_cu.ssJoa
o_ l)rolxg_ed _At_ l_econlrt:ndc({ Practice
XJI207,
Mea_'u_,nt
P_x_cdur_ for L_1_ennlnntlenof Silencer Effcctlvc'nc_aIn l{cduclng
F.nglnoIntake on l_Mml_*it
_Sound LcvI_I",Prc_xcntedat [J.S,E,P,A.,Surfnee
_['ran.SlX)rtation
]_.xhatt'_t
Nol,se _n_pot_l_, DllcI_go,'(_I:o[_2r,
1977.
i̧
243
1,
!,
;,h
,_,
j'
[_YlWI'IC_ J'DI1 1;IGUIII'LS
hn
Incident
l]e
Reflected
Z
Inoec u ce
Q
Dlreetlvt
h
Il_n
11
b_'.atmrcll_at
l,l
_lffler
D
Engine
I[,
ln,*_erL:Jon lo,']:] (L]L)
'17,
Tran._.ni;i_Jlon lo,';51 (LI_)
_.{)_24
5.0
65 tallplpe.
65 inch
]onl;
Lal]Pil_
18 inch
long
e_hau;_t
]8 er.hmmt
I
;
.
pl]_
pressure
an_)ltLucle
pres,.]ure mt_)lltude
ty
factor
eon_'lLant
dlscallee
volm_
(|lzspl ac_._c..nL
111C|1I|lnn)_.t[:C,
F/S
[e_C per .';(?c(?nd
70F
70 deffrc_
Dn
Unit
DI3A
l_niC for
3600 IU_|
3600 llI_l engine
for
pipe
I"nhre|lhelt
iwel'_t(_o e_hatLut
=_>und pre._,_ure
A-._¶_'ighted
]onll ffaifElel"
2,1 Jnch
level
_ound
ga._ t_Ix_raLure
in dcclbel_
in dec:llx_l_
level
_l_e(I
244
r,
_
.
- .................
•
,
FIGUIIE_wrI_8
Flguru i -
bkmu_ry of I_mic De,_leuCon_Ideratlons
FIP_Iro2 -
Flow Chart of Major Evaluation Teclmlnuc'J
Flgurt_3 -
k'xhaustSystem Scha_tatlcand Ewtluatlon Paranx_ter_
Flcnlre4 -
In_ertlon Loss Versus ._luffler
Voltuncto Engine Disnlzmclmnt
Ratio for R Wlde Vm'iety of Applications
Flmwe
IYc_lrnl Guide
5 -
Derived
fz_n
Datlt
Such
ll'.] 'nlitt
SIlo_m in Fig.
4
Flaure 0 -
Tran',_'nisslon
Lo_ and In_ertlon Dou_ l'x_nNel.';on
Analytical rbdel
C_}itl'Cdto Insortlo/lLoam _]ea-'mred
on a Single Cyliniler.
Four Stx_ko I_lglno Under 1'_11 Load at 3600 IlP?I
Flgum
7 -
_ry,
l_lgure
I] -
TyPical Eesults
from Ili_cdnnce 'l_lbc Insertion
Lo_s _lem_lr_mnts
Using l_htteNoise F_cltatlan lind'l'ran_;nim_lon
L0,_m_]ea:surc_mnt'a
Using Sine Wave F-_cltlttlon
C_parcd to Analytical P.cbx_Its
of I_l_rimcntal
Teclmique_
Flf_Ire 9 -
H_Ir_n I_rge lleverborantChamL,
cr and E_al-Anecholc Chan_cr
lelg_IreI0-
C_Ita_],Vlmv of }{c1'_on
Lnrge Engine Tout Facilitic:]
Figure ll-
ComparL'_onof /tnal.ytic_tl
to I_perlmcntal Hc_ults U,_]IngIIw)cdunce
Tub_ and Flc.or_bulltedMicrophone
Figure 12-
Oar_arlmn
Of Analytical to _pcrl_mntal Rcmflts lining Single
Cylinder,
Four Stir)No l_glne
Under Full Load lit 3GO0 lll_,,I With
Floor lbuntcd
Micropl_ono
_Igum
la-
Co_parlson of Imix_anco Tulx: to Faglne [Inn}_c_'nalt:_
Using Single
Cylinder,
Four 8troku faglnc
Under FOll Load at 3600 I_PI.IWith
Floor Motmtcd MicrOphone
]Plgure
14-
Transfer
hmctlc_l
and Coben_.ucut_nb'_lrc_cntu
for _Imple Pas,s _lufflor
Wlth 4.5 Inch _ColldF,
xtcnded Inlet nod C_tlet Tldx?:_
l_rlorto
Perforatlens
]Figure15_
TI_¢_Domain l_valuatlos._
of I_xpnuslonChn_t_crsUsing ,91nglelh_Ise
_¢citatlos
]Figure 16-
Cc_p_.rlsonof In-sortiesI_'_;_
on Typical Industrial l.hlffh._r
Using
Thre_Dlfferea_
.Sourcea (Microphone
at 30 Inch Iluight for Intnko
14e_m_nts
and 2't Inch Ilclght
i_or }_hnust
L_:n.'n|rc_,nts)
l_lgur_
Comparison of Impedanco qh_lm, to l_glne
50 Fc_t From Otltletand Four I,'cct
Illgh
17-
N
245
Ecm_ltn
With _licmplmno
FIGl_d_ CAITrI_S
(Cont.)
Figure 18 -Effcct of Varying Tallpipe nnd Exhaust Pipe Length on I_rgc Engine
E_must Nol_e
FI/gLro19 - Effect of }.Ic_urcmcntPosition oill'.hhm_tNoi_e lh_m Single
Cylinder, Four Stl_ke I_iglncUnder Full Load at _f._O0
})_.'.]
Flg_iro 20 - Major Tcchniquca H_mkcd According to Accuracy nnd Co:_t
246 "
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COMPARISON OF EVALUATION METHODS
MOST ACCURATE?
I) ACTUAL ENGINE
2) STANDARDENGINE
3) SIMULATEDSOURCE
4) ANALYTICAL MODEL
5) PARAMETER
EVALUATION
LOWESTCOST?
I) PARAMETER
EVALUATION
2) SIMULATED50URCE
3) ANALYTICAL MODEL
4) STANDARDENGINE
5) ACTUAL ENGINE
'i
Fi_u_re20
266 "
f
i
'
A COHI>_F.R-A_)ED
APPIIOAC{IT_{ARD
I,I',RFOR_ICE I_IEDICI'IOHS
FOR ]_HGIHI.',
EKI_US_' HUI:IrLER
John F.,Sneckcnh_rsor
A_ocl¢_ga
l'rof,_nor
llor_ntu_nj
U.
ft.
gnv_ronment_l
_V
2b._O_
l+rol:ect;ion
HcDonnell-pouglam
267
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to
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Lo fr_uhman
only
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Hy
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be
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I hlwc
of
ffatlonztL ,q¢_nc_
for
for m_£flcr
at _cl_on
Indmltrlcu_
put_-aided
dc_i&_
Ald_ld
capabLlitica
Appxo_,_ll
Toward
-
tc_tl:l_
O[ thcn_
rcquLrcmcltt_,
Rradc
of
durtzl_
I hltvc
for
ycaru.
conccrnl.n_ nW _c_ul_|tor_ policy.
Inc, o_ fitou_hton_ N[ under
to
at _luon
attumpt
d_wlopmcn_
all _llnlmlytlcal
tool _nr tim
Y_r_orm_tncc
De,parlement0
S
26a
expand
atudy.
for tlm t_n-
tim_
_f£[_r_
f, nl31n_ F._hauat
com-
Improved
c_mplim_nt
dcvnlopm_:nt_ d_nIBn_
for
Am Larry
to an
_low_ toIlny at th_o
of
II
the cal_t_n_
At tha_
an i_porc_mt
_nufactur_
Prediction
i
to
Induatrlua.
_a:_ vJ.r_unllz_d_a b_in_
op_Irai_._ton
w_ck_,
_nd I £orrm_latcd n work plan
dccLd_d
Impi_dnncc tubo r_fflcr
(potentially)
and
_l[tcrllO0_
to tlm _alnon l_c_uarch
Lt waa
:mcc_._
Lhrc_
the
_ltl_
I p_rtlclpat_id nn one of two aunm_cr £aculty
theft _ur_mc_
con_td_rahl_
in
II letter
yet to tic t_kcn to court
_¢cok period
after
dcvc[optl_c_t
lit
197[,
Somcwhltt
d_'Ji_n,
only
En61-
hfl_clin_ muat hu a _ood one and _m_ybc_ qttlte
of $¢:_©_rch,
on-_otn&
uinc_
rcuc_ttrcho
_radin_
- wtth
DIrchanicnl
University
[totlr_
project
the
be coi_sLdcrcd by tileEnv_totn_Itlntalpro_cc_on
Foundatlo,n _rzmL
d_ll}_
l_d
Lhr_c
utudc_t
h_
Co [_rlldut_Lc
student's,
l':rlha_on, vtc_-prcnLdcnt
comput_-nldcd
study
tllaL nlufflcr
_ i_affficrs
uhou[d
of
Vir_inl_l
projct:t_
fnct
the _un_n_r of 1975,
pavtlctpanta
an arcz_
at NcsL
only
'hlbcitnt_
of courac,
Durlns
the
bcc_u:L_
and
bcc_m_c
merit
_n_l:_ccrin_
're,old,tory policy'
humorously
been
frOll_ fr_:}|_lll_l_
L_tu_ht
b_cn
i':•
l)cp_lr
£_
three
has
_y_po_fum_
and
evaluation
th_
"Comput_r-
Hu_flcr_"
is
_
. r::.
I'*_'_i
¸t :"
V_
"_rk__ _ I_'._;,_
",,/_.
,_'': ;r
,
* -[
ba_n_
pr_cnced
to
CO_l[_U_-/lld_d
in
_d
O_
of
of
th_
p_per
JudBed
(l)
O_
_h_
_tc
Thi_
_|lr_¢_ of
1976
¢orpo_at_d
t_el_on
o©minar
into
n
Inclu_tcien
e_endcd
m_fl_r
tht0
th_
_
a_
bc
to
I'educElOll
hcr_
tll_
_L]I
I_l_hth
Dclll_n
followed
today
e_li_*_
ll'J II
de_lfin
be
Annual
for
all
I_o1'_
An_lyl_L'l
by :h_ll_c _-o[lallcll_ll
a_l well
a_J on
_II(!
a.J llll llnalyticltl
function
IbellCll-_y]_
t m_chodo_o_y
Ilu_,m
a briu_
which
_ffcc_ivc
then
tjec_L[ll_|y
In re_u-
to
prowl,It
tll_
Thirdly.
¢urve_.
rn_t_c_al
ou_lc_
nltlff]ct
Fln_lly_
which
ptH, c:c clu!lt
pcr_i_t_d
_ paran_ctric
_o prodtlc_lficncrali_.cd
for
work
providvd
of
the
I;_ pre_cmcnd
m
paper,
399
extended
_n thu
corni;utcr
Ln-
p£cp_rcd
cilpal)ilitict_
development
con-
wur_
ucil£_an
._mly
_rnpl,-'
_or
an
cornputuc-_idcd
_ev©ral l)otenCLi|lnthl/tion_ cn _pand
capabil/tie_
_III
jlco_r_l]l
of
e_hm_L
Admh_t._r_t_ion
i_provvd
_pvrlrr_Cation.
of
fvnLurc_
mzd Space
_fffh:r
K_SA con_])tltcr
dc_/Sn
uxtenlsion
A_ronauticts
du_cr/i,_lon
Dc_eIl_:J._t]. _or
ofJ:er_d
coJIiputec-ai,lcd
(l_/_ctl_:lcll
pro_Irnl;i
with
_o cor_plcment it_ on-_otn_
£nl_t-_xc©nded
Th£_
nlentionvd
_ppro,tchc_
NntLonal
e_ne_l_nL_ and opt_m£_tloll
_dent_led,
Ju_L
paper
r_ccnr
_t_ndcd
da_gn
Syl_lt;'_ H wl|[
tl_llll_tl_
_ownrd
r_lffl0r
lng_mpe.d_nce tube
of how
[976
L'tC OJ _lli_
noi_
Hy pl_llt:|tion
coi_iputerprosclull
palter
progr_u_
cornputer-aidell
cor_unicat_
January
_1_
1_lurit,
labol/n_.
Sccondl7_
_7n_ema.
m_d t_
i,o_:_Lblu
in CmllpuL_r-A/dod
_roS_lllll
towiIrd
_11_ir_or_ r_C_ll_
I:in_ain_¢ _oturc
ill
_llau_t
the
e×tcnt,
:;y'_teln:_.
ProBre_'_
COIfl_[I_
_c_hn_qtl_
Inl:ory muffl=r
exhau:_
"Som_
al,plic_Iblli_y of
t1_,11_.l|tlf_on
pL'udic_
prc_cn_d
c_lC/l_cd
of
II_Q
to
vehic|_
_ paper
Op_l_l_on
_]1_1
Lh_ increa:_ed
t_cllodolosy
char_|c_r£_ic._
_Ina_on
e_ht|)it
proKv_m
_he (ic_i_n
were
no_l: _our _cctio[| of thin
RECENT
CO_-IPIYrER-AIDI,.'DblIH_FLE[I DESr(;N
_lunJal
(2)
hind recently
tat£J.Lz.tn_ a mod_f_ciltl.ol_
propo:;cd
to
tht! colnilut_l" t_v_t[u_tLiotlo_
a
rcvL_ed
a prcvl.ou:;ly
_ind till,Jr;
vcloctty
t:t'_ti_:ifct"
mat.rl_
dcf£ttL.d Vt_[ocIty"
il_:i_rt,
loll Io_
nLethod_
ratl.o
fui1c_lonp
prc.Jt]ure
COtlpl_tn_
bt_tt./12cntl¢OU_ll;ic phcllt_IIlt:ll;t
.iI_tl_ncolnpI't2:_tiJ.blt_
nlt:_ll_
_lOt_o
mat:rlct:a
for
wlrlous
l_crc rt_dt:fl.llod con:31dt_rln_
ba*J_.C znu_ler
cletu(_t_t_ '._re dt,rlvedo
l_or _t_ro lll_ttn[lo_
,ahcrt_ ,_tlch of
I:hc t:hrot_ typcn
Lt_ipcdttt_ct_s_such
ctl*Jt,for
o_
non-;_cro
l./ork by
in_dtl _|o_J.
Karllopp_
the
corrc'Jpt3t_dct_ce
From
FJ.l_t|lt'(_
2)_
rf2cur_iOl_
el: _ll°j
(3)
on
thtl cqul.V_ll.cnt bond
Unlike
ght_ cltut_
d_.d t_ot:app_ttr
iil_)tlclltl_
cnl_.nc
c_h_lust
In COllnCct;_.on '_Ith
_r_tpll model
t:ht_ flu/.d of _n
st:ored
by
t:ht_
l;[it_
cotllputt_r prt:-
oI_ i_ lullq}cd iinl_flt_r (,';co
l.ncl'tI_ll clt_ii1_l_l:
_crc
COIICltlD_.O[Ii hOW_VI_I.'_ tl(:_Int'.d
I:o bc
and
l:hr_t_ dl/nt_nrlil.ori_tl
_[ccl_tJ
t:o h_ttldle Lh(l ol_codln_Ul_tlJ.on_tl
l:h_|t;r_ucl_ tl onc-_llmcll:llonil]. ¢olliptll:crpt'o_l.'_Im
l.i|_hl.ch
_irt_ InlportIlllto
In tl _h_=n r{:c*:ll(:
l_tl)t:lr_'l'o_InE;
_ind Crf_tzl_cr _4)
forrradal:c
a m._tthc.,lultlc_tl
dcncrl.ptl.on
rnuEfle,lr.
,'ice,
Fl/lul.'t:].
_;I._1_
_hc
Lorlrat1_tt:cd. Tht_ at_noclal:cd
Co_._Id nol: tlc_irtll:cly d_r_crl.b{_ col1_pl|c_ttcd xlrtlf_h!r col_l_ural:lol_r_
_lcoLIS_c
I:o be
Eilu_l?Icr:i,_n bt]nd
_:ht. colIlpl,
l..It_cccl_m,:nt
_l|'t,_t:(l
t_J.cmenl: con_p_.ir.erproEit'llm w_t_ dt:vt:|opcd
_ht_
t:o Ol_t:of
fOrl_Rl[tltlrc1_II:J.l|__icoti:H:Ic prctiiJtlrc _|nd Voltilll_l'low r_tI:c
l:crmt; oi? l:hc!vol_.ir_l_
oI_ fht_d
rnolnet]l:umo_
TrtllltJftlr
_ind lloJ.'Jt_
J_or L_./o-_l_l'ok_c|l.qJ.tlt_'J
wJ.l;h pot#t_r l:ul_cdi :ll.lcllc(.,tl
_htlutll;ll°
_n
convcctlve
,_.e l_i_tlrt_ |.
_rtlp|l t:crlnrlhIltl |icell rt:c(:tll:lyr_portt.d
dJ.cl:ion o_: poNt_r
the
trtln:ifct" IIl;ll:r_.cc'd
corrc_Jpolldtrd
_
for
_oI- t!_[t_lu:lttElUf[_Icr'.;
t_l.
121_II1_,_t'_
riot,t.
AcotlntLc
_olut_.on
WliS O|)tll_.|l_liZ
•
l
_-IETHOI)S
of
the
oi" thin
[ly
l'll_tte
ut_,zd vi_rl._ti0n_ll l_cl:|lod:_t:o
_;coustlc
wLrltLtLonal
clern_:ltl:
l_icld
cxiatlng
In a
Inct:hod fori}alliil:lon [or
lTlet:llOdl_,
For
thl[l
approx-
270
_
.
--- .
_a
_:_:,_,_.i_
_
JLIItLItlJ
o[
lJO1Llt_.o[I
IlUlllCl+_Cttl
'JIIbt+c_lOll"J
tion
EIIu
of
nod;l|
of +lcoustic
dc:lJ+l.-l_d
t11LI[_|(_F
[otlr-tL'FJll_llll[
Lir_
EO
l)l_Illncd
to
Hl)])r(++;lchl
e_lll_nL_i.
I_t'_s'Jtit'e
_tCOKItIL_G
U_I_(I
IIIt_Lhod
_l_ld:li
._t
lu_J!l
show I:llllt
titt'll
tli_l:tlot'k
J='otJr-L_rtil_I_;l[
when Zll_l)Jie(l
to
t'+J
defJiz+.d.
II_ldl_
[)y
I_h_{:li
fur
with
_llLo
o[
The
|'til+lll_ll_
LilU
¢oI_I_;iIILtl.
mtiEfler'J
d[v_.(iud
d_!iCl'_[iEIve
wt.i't_ thuil
t_l_i
{r;lll_Jlll[_i{]_Oll
llltlf|'[i3F
ll:ll'illll_cer'J
¢p+lchnod_
{r_lll_Hll_+l:l_Ol%
doL_JlflZl[[l(_ th(_
t]ltl
thl:
Ilbl+r
,,'ilr[il-
of
L=c_ttiV+l_t_ll[_
p,ll';ilZlL'_l'['2i
II;Iplbr_
cotnpltc+i_ed
the'
Ilul
prcdtctiutl
IlOd;ll
Fut:tlr_2
;I
t_uri2
i_h_JIl
:sh_ip¢,d chzui_hcr:l
|_OCwh_Cch _l/lllCW:IVU theory prcdic_i_+i=:idre no_ ;zvzli[;itile,
ts'Zili'Jini_in/osl
Io'JIl
u'Jin_
tJiL'J
prc_tILcI:Lnn_
:
I_XTEN_IONS TD NAflA _III]:["LEIt
I)l';_;lGtl CO_ll_U'i'/;k
PI(OGI¢ADI
Thtl _ihovu
+la w_ll
Ehrcc
¢ltl ocher
to
dcvolo
computer
ziwlll+lbl_
n_¢lcil
dcuitln
_ncCurJn_
Such
_ltll_i_.llEl_d
It
P_{{lL?ri_
i'oi'
C=lJl_biJ_Ly
would
I)c
|_Fom
til=ci:lfJ.c+ltIOll:l,
_l
_,_:11
devc_l¢_l)ed
/_htIy_
lill(I
blliill
_(ll"
rl_£lCi_J+Vi_
Itilltlll
/iwlllililll_
+tot iiIcllli[olit,
d= iil¢lut_t[
I]llorL
tl
i[lu_lct+lltcil
_llCOrl_ol-_it_ll
_lli_o
colTil}tl_ur-_i_il_'d
I!l_$_Ulllll_(l
hy
(ten
Ililill_
PIA.S&
271
tliroilllh
wi_ck:i)
li:l_ll
tll¢_ lll+lnn¢:tl
the
ovul-lill
ctlnililct_
COllililllC_r-
rlcllcnl_
tlc_ii_;ll
'l'cclililc_li
+¢l=l)li,:=¢l)ill_y
_u_CilLl+illy
ll¢_
oliE]i?t
i_i'oJ=_c_¢_¢I
cX]tiitl:IE
/lltl[_Ict';J
Lhc lnoli_
lll_lf[l_l"
lll_l!E-i_l:i_lliJi_d
l:htl
tci'm
+ lliv)tlt_l_llJt whicli
1
I
t:={[iL'r_iil_lltt_.
cotnplltcr-ziId_d._ulflcr dcuJ.llil,
c+ip_ll)/l_Lic_
on tnll_ci
Vl_urc
inIJ_ll?_+tl
r_l:llt_l"
were
iilun¢_di+itc
¢lcriigti
lilill_d
tlli_ory.
;i_ruem_!llt
the lilt;fly,ill
/illt]
op_lllli_tJ.ollO[
]li)_Y_Fi
J+_,nu_r wav¢_ i_(ltlni:l.orl
_}o¢I
li=_!Chod_ I_]iicll
I) c_mpuici_r-iiJ_di!d
protlr+_in
Lit
new n_t_thad:; I}f
proBrc_l= In
=11¢; n¢_/i_" _tA_tl_l_.
l:Im_
zire
rclll£1vi_ly
|}oll_£bll_
llrOsp¢:ct_ _or _orc
in
tnctlsod
w_t[l
I
ol_
lii'oEl'lllll
Illl
i_Ki)llll?ll[in
No{l_'
lll_ii_ti-
{:h_ilniii_r
T N
I)-7309,
l,
Th[_
computer
l)ro_ram Is hlrllcly b._sed on the work
Thc 1_ey _c_Ltu:'c_of tile _A
co.II_uter i}ro_r_Jm_re
of Alfrcdson
nnd Davleu
li'Jtcd in F[surc
(_).
5.
Ill ot'dcr to api}rcci_t.cLilt coIi_[)Ic×Ity
of _l typic_ll coilmlcrl.c_l
mu£_Icr
relat:Ive to th,! c_Lstln_
c_li_Lbilltyo[ L]IL_I_A_A coln[_uterl)rosr_im,l.'[sur_0(It)
'J[iow__i _Ir;lwL_l_
of _i Lwo Lubc-Lhrcc
[_;_!iizlu_[icr ti_Iicn_rom p_l_e 3[-_7
ll_l:_(li)oni_
c_[ _o[!_e Co[_:ro|j l]_irris
i cd°°
_£oii of Lhls mu_'_[cr I_[iol_[_
ll_ Fl_urc
A_
6(b) £1|u_Cr_LCc_
:ulinttL_ported c1_11_l)ct'_
lind 1}cr_or_i_e_l_be_
c_Is_In_
the projected
o_ the
_[_d ult_ol{led v_l_-
_cvcr_ll _cIltl_e_j uuc|t
_Irc :toL _'_iidi|yh_mdlcd
by th_
I_A_A conip_itcr_ro_r_m.
A._ _m Inl_Inl effort
Lo c_tc11{|Lhe _/A_A comi_lIccr pro_r_Inlj _he pt'oSram
_t_ coi_ver_cd fr_:n Icolnl_Ic_ chIIn_|Jcr
I ii:Iil_y_LsCo _ll|div_.(lu_1
_ec_i_rli ii[lal_f_lJ.
Further:
cfl_orLs _erc dlrcctcd
ill providli_
llcc_ioi_l||:r_odQl_for l_lu[__md _wo-
]_|_ll111_l_Icrli_cCloft'J
wit_ch ttrc i[_i_._¢o11_[io11
in _[_lIIoll
111tlfflcr_° For _lll _t_c_ion_I
_/nrLnb|(_ diameter
of _h_:_c i1_Linl
plpcs
i_l_d
chiln_bcrflwcrc [_ow pcrniLttcd, A p[ccorlal
d_¢rIpc_on
c_cn_ioiltJ _o tile _IA_A coi,l_u_r pro[_r_m Ii__llown in Fl_ur_
Us_[l_ _hc _ccti_Ll
al_l_ro_ch _o _hl_ l_redlc_io_ o_ _r_n_mi_i0n
Io_
p_r_Ic_ll_tr rmJ_[Icr rc(lu_rcd L1_crl_l! i1_dLt'Ic_i_i_nLo _hc _lo_ lo_Ic o_
cnmpul:cr pr_}/IrllmoA £|ow dln_r_m
dCl)IC_lil_i|_ow Lh_ _'rn:_mi_1_n
_i_nc_(by _t:ppi[i_ Ii_dLvldt_|ly _llro_i_l_
_h_ r_ec_lol_al _t)roti_Ln_j
eL_[i_r _ibtil_t__Ind/or plotted
cnvlro_:i_
_urm i_ _hown
iz_ Fi/_t_r_9.
l_
7.
for
t|l_:NASA
i_ d_©r-
compilln/_ _:_d
_c_ioi_In_
o_ th_
lind p_occ_d111/_L_i__o _ind Liiclu_llt_
6 t|i_ _yp_ o_ cn_l_nQ not_rc_ Impedance°
.272
_._ . ,.
. , ,_I¸'•
F.XAMPI.EOF COMPUTER-.AIDED
_hQ _xContIcd
colll[)utv.r
QVAIUAtLIIB, predictinBj
_uffler
ba01c
STUDY
t_d_lu
OF HUFFI.F.RDI..'SIG_I
proBr(tm uervud
ekcj
of: the,_xtended
p_rform
analysin
of
exr.cnd_d
_ourth
_h_
• nd_ of
was
tho
of
sx_©ndeo
shea o_f_ot
th_ _k¢_ch of
chABEAS
of
_n_¢r_d
he#
tnlAt)
inlet
And
th_
values
la
fixed
inlet|
whil_
(or
th_
rapidly
bo_h
lncr©A_t
chc
outlet
consldorcd
Of
_hc
_rt:quenci_
toward
rc_uultant
witl_
internal
_hl_
influcncc
curvun
doubl_
th{_ on_
rc_onan_
*tpproachw
ln_inity.
onc-
i£_ed
nmoun_ of
on
£or
the
nhortinB
Of additional
Obacrw
that _
n_ _ty
for _ho
initial
wtlu_l
oilily|
not_a
_
B _hu
frequency
its
the
tranomi_ulon
frequenny
ono ht*l£
di_tOl_CC
off_e_
rul)rUucn_ln
re_zona|l_
_requ¢:ncy
inlet-
i:sa t_d]ul_trexalnple 3hm41nB
rc_on(tnccz_
parti-
In Fi_.ure 10 l)clow
_
outle._)
r©_onan_
I0.
in Fi_ttru 12,
VAIuc_
the
con_tnnt_
_tre _hown
r_pr_n_ln8
of
to
ittt_i_llly
bctwcun
pipet_
teclmique.
|lie e_tended
dlnt(mcc
dcnurali_cd
_.
tube
function
extenslon_
S_o Fi_ur_
qBAICt¢:I-WAV¢_ IcnBth
l©nB_hing
Ath_r
wlth
amount _ .
maximum
a'J a
_tffler
extended
belnB
din_ancA
to ths
o_-_t:
confirmLn_j
_tau its capability
bchItvLor
consider
KucpinB
of off_e_
o_ tim ra_onaat
I¢nsthin8
_00
chamber,
lons
proErnm
For _xnBple,
An Appreciation
losn _or _¢vcral
I000 ha
tha
th_ muffler
F_.flur_:
II provid©_
tha
chamber
by _Im varylnB
_n vAlu_
bBhAV¢o_
parameters,
a_pnnalon
lvn_h
t{ASA computer
tr(H1uml0_iOl_
muf_lor
d_aiBn
ou_l=t
of
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1)
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in
OF CO_IPUTI£It rllo(i, ltAM IH RI!GULATOITY_{UFFLI!I{ I.hBELIHO
rc8ardn
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toward
muffler
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tho
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2)
thin
by
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Information
policy
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_ 1_
o_
Al_o_
reflpccC
notne
en8int_-
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n_at_n_
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applicable
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l)
calculation)
llnpcdttnct_j
rcducttoa
band
nunSct,
th_oretical
notlrct_
IlOlU_
'lntathodoloSy
6)
with
utatenlenttJ
tllnralatLon
rcsulaCory
tnnertion
i, rocedurc_
nourcen;
in
lllt_Chotlolo_}y
loaa,
_valuatlonu
of nut[ant
I
anltlytlcnl
(tranumtn!lton
and
thin
tl:tlt
tills
(by
CO_nll_llliczkte
co_p_ltlabl¢_
_a. eventually
tbt.qlch
cotfftsurattonap
npclrnlzatton
_ov_ard
would
tl_t_urn_ll_
of
cart "i.canurc"
charact_rintlca
Nyorem_j
a
follower.8
tht_
cx|lau_t
applicablllcy
114
I 'potentially
r_duccton
ain,t©
Cite pouaiblc
U_lCftllnetlU
labelJ.ns,
• Irrmthodolosy
i
to
uar.ful
poanthh:
which
ttael[
for
_EI,ECTI_)
1.
Snecltenberger,
d. E. t "Some prol_re'Jtl
/k_aly_lrl
lznd Optllnl_tatLon
o_ Ba_Lc
Nol0e Control
111 In_ertlal
Coll,bulitLon
1976.
2.
NutlJalj
M. L,j
"VclocLCy
l(atLo-Cum-Tranufur
of a Huffler
with
)lean Flow",
,j, Sotznd
pp.
105-19, M(lvch 1975.
tit Con_pueer-Atded
E_hau'Jt
Sy'JL_ul_",
EnsLne
.qclnttl_lr_
De:d.gn for
L'L_hth _tlntla!
23 pp. j Jatlu;zry
Hcchpd
for
an(_l Vlbra_iotl!mj
tile
EvalunLton
VoI.
39. No.
1,
].
]_trnollpj
D. C,_ Dwyur,
IN. A, lilld H,lrg.olil % D. L._ "Computer
Pcedic_lott
oE Pot_ue ,lod Noir_e for 'lMo-Stcolte
E_Bin_'J
t:ith
Power Tutzedp Siletlced
Eahau0cu",
SAE Paper
750708,
14 pp._ AuSuot
1975.
4,
_OkII18D C. d. and C£ockerj
H. J._
ttPl'_dl_LlOll
of Tl'*tll_tlliUOIOn
LOOll 111
Httfflor_
by C|Ie l,'lnitc
Elt)ment
Mt!thod I', ._. t_cnutltlc_tl
So¢,i_t_t
o._f Amurtcoj
Vol,
}7, 1(o, .1, pp. 144"fJ_ J(iIItlIitly
J_gt'._.
_,
Alfr_dnonj
R. J. nnd Davlt_o_ P,O,A.L.,
Colnponunt=",
.J. Sot._tnd atld Vibration0,
April
1971.
6,
T=nsrrltirn=_
P. _tlld Dlboll_
W. l|._ "Adjoin|
Inle_-Oucloe
Lt!osEh Htiffl_r"m
Procce.dinE_:
1973 Nollm-Con)
pp.212-7)
7.
p_terl_k_
W. P._ 't:;_t_m_ic
H_:Chod to D_termtnu
the Acou_lca!
Charact:et'£ntlen
of S_rie_-Pnrallul
l)tlc_ ConfiBur_t_lon_
Uotnfi Tr_mmnlt$tl£on
H:t_ric_'t_
Pro_ucdinSflt
Third
II_c=rzt_unc_
SynqmrJltllu ot$ UliLV_r*li_y
Ro0coi'eh
in
Tranapor=n_lon
Noi._",
pp..533-45_
Novemt)ec
).975.
ft.
Fl_nd_n,
1). C., )'lml)u(|_c_
o_ Bnai¢ Mu{_l_
Elet_unc_"_
CombtllJi_on
Ensioc
_=min_tr,
9,
Erlk_oll_
I...I._
"Powo.r or l'rfl_*iurt_
- A DiOCU_IItOIt o£ Ct_rrt_o_ A_urlt_Civ=;I
_n E_t;_u_C 'Jy_t:unl
Acot£oLic
I_vltlu+;_lOll",
EPA SuP flier TrtlnttporClitton
E_d_+tu_ Nolo= ,_ympo_lum_
33 pp.,
Octoher
1977.
10.
i
REFERENCES
Ol_on,
D, A._ Nordlin,
K.
tlf Tru_.k EKh_tl_t
Syoecm
Oc_ob.r
1977.
"Perfortr_ulca of E_dmuot: Sllenc_r
Vol.
15_ No. 2_ pp. 175-9%
Tubtl; A _oo1 fO_ _|1_ Rene_rch
El|lh_h
Annual
Nol_u Control
32 pp.,
.Mnunry
1976.
I). and Seilu,
E. J.,
Noi_e H_n.ur(.incnc
"
277
Qu¢trter-Wavu
O_cohur
1973.
n_(| Oevt_lopm(_t)_
_n Internal
"Tcchntqtmtl
_md Probli:ma
SAE Paper
770B95, I/, pp.,
___/ ......
.,.i.,..
__,
i._"
tel
ID)
IQ)
(a)
Figure
I.
A TY_ICA|.
flTRAIGI_-TI_OUN|
EXI_U,_T HUFF_R
(b) 'ANALOCOU3 CI_RCUIT FOR _'I|_ ZVAI,UATXOH OF
VI_l
(c)
VRc_,n_
ANALOC,O||3
FOR_JI._TION
CIRCU_
FOR Ti n:* RVALUATXON OF
FOR VF.I_CITY
I_ATIO-CUM-TRANSFER _IATRIX I_T||OD.
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REVIEW OF IIITERIIAL CCIlOUSTIOrl
EflGItIE EXHAUST11UFFLItlG
by
flslcolnl J, Crocker
Ray H. Ilerrick
Laboratories
$ci|ooi of l'lecllanic_l EnglneerJn9
Purdue University
West Lafayette, Indiana, USA
;
J
SU_AR.Y,
This paper w111 describe types of muff|ors In existence,
discuss defloltlons of muffler perfomance,
briefly review
historically some of the theory developed to predict muffler
acoustic performance, describe some.of the work done at the
ilerrickLaboratories'on l_'edlctingmuffler attenuationj and
lastly comment on the possibility
bench test
for
a ._ffler
of desi.qnin9
a practical
which does not inyolve
an engine
_1_a source.
INTRODUCTIOt_
E_ha_st noise Js the predominant
most Internal
silencers
cod_ustion
source with
engines and thus mufflers
have been designed
Unfortunately_ _lthough
noise
to reduce this
the acoustic
and
noise.
performance of
a muffler can.so_etines be successfully predicted in
the laboratory
_lth artificial
(loudspeaker
=
295'"
i
v
type)
_curces,
until
recei%tly most
attempts
_o predict
of a muffler
on an cnglne
ever S in the
last
few
_oars
now prediction
of
the
acoustic
on engines
be made
known
can
effects
Most
muffler
on a gres_
Beoent
deal
U.S.
automobilos
weight
efforts
to
acoustic
dJsa[_[,ointin9 .
progce_u
ha.';_cun
performance
with more
[_urfoz'l.._,
.co
]low
made
,i,d
¢E real muffl,:L.
_ccuracy,
although
on-
remain.
designs
manufactured
of empirici0m,
to improve
has produced
increased
and
expected
improve
optimize
that
fuel
this
of
to :_ave
performance.
pressure
of mufflers
experiment.
efficiency
pressure
models
rely he_vilj'
and
acoastic
the.erotical
performance
still
experience
legislation
in mufflers
Xt is to be
near
still
have. buss
the
will
of
increase
tile
*)till fLxrthor in the
future.
_U_'FL_,n
CLASSXFZCaTIgH
Muffler_
reactive
and
of chambers
can
classified
dissipative.
most
the source
(the englne).
sound
lined
energy
in
do sometlmes
with
the
volume
incident
incorporate
mufflers
and
snaps
acoustic
material
it into
to be partly
fact some
tw& main
Dissipative
acousti_
and converts
can be designed
tive and
of
in_o
Reactlve
of different
reflecting
hand arQ
i
be
types.
are composuo
and work by
ent_rgy |>nc_ toward;_
mufflers
which
heat
on the othu:
absorbs
[1,2,3].
the
Mufflers
re.as.tire and
pertly
dlssipa-
combustion
engin0
mufflers
internal
adsorbing
296
materials.
However,
•
this
mutnrial
usually
t@mpe_'ature
_ ' ,.",":_
i
..
; :
'!' : _[
.
conditions
fa'tlgues.
today,
Thus
are
of
can
occur
shows
some
typical
chambers
(cbambcrs
In
more
+.' .
, ,+
chambers
some
or
incorporate
diss[l)atJon
due
to
further
uubdividod
is
addition
is
over
are
viscous
the
in
suddenly
types
(which
cro._l
of
pipes.
to
arc. usually
a|*d one
Som(_,-
re)soil,*tots.
produce
t_i(h= brasch
high
frequency
is
oft(u,
_ruattld
by
Int_rf_r_nQm
k)ath
lengths.
297
3
uevural
reversed
flow
reverse-flow
typical
Pigure
There
la
ruflnct
car.
rev(}rsc-flow
IIolmholt_
used
2.
connlat
the. flow
increased
(side
A
Figure
1
expansion
resonators
siml]_r
muffler;_
are
is
Figure
These
I{uversc-flow
shown
into
[4,51.
configurations.
w|licb
th_n
area
tube
:itralght
different
of
the
another
by
patches
types
mainly
concentric
_uch
in
attenuation
traveling
which
resonators
In
be
of
low-frequency
louver
nolse).
1,
not
eompriI]ed
ok
shown
large
ll_imholtz
"
melts
*t_uffler
reoooators).
connect(:(]
end
mufflers
do
types.
muffler
As
chambers
....'
and
a photograph
muffler.
and
severe
manufactu_-ed
straight-through
many.different
reverse-flow
times
and
reverse-flow
in
IIelmholtz
built
can
u:iually
decrease{[)
branch
or
reactive
and
arc
two
a
inuff]ers
muffl+-_rs
shows
type
Nevertheless
in
stralgbt-through
be
clogged,
mufflers
the
of
ties.
J_eactivc
then
because
becomes
automobile
tile reactive
materials.
still
and
most
absorbing
dissJlpa
deteriorates
type,
allowed
He;it
although
to
o_
occur
_ound
automobile
trucks
t
;
can
use either
reverse-flow
or
straight
through
mufflers.
DEFINITIONS
The definitions
use
will be given
however,
and
level
measured
sosreo
to measure
the muffler
u_e is favored
by
Noise
preset*re
the
power
is most easily
favored
between
and its
of
predicted
Reduction
l_vsls
in space
that
with
point
and
quantity
by manufacturers.
is defined
incident
This
on
as i0 logl0
the muffler
is the quantity
theoretically
engaged
in the
is a convenient
This
power
transmitted.
those
loss
(TL).
sound
nomenclature
at one point
inserted
Loss
be noted,
is the difference
Insertion
the ratio
ssnnd
This
[7,81.
Transmission
common
arise.
pressure
the
C.
sometimes
in most
It should
use different
(IL).
without
the
authors
Loss
and
of
can
perforinance
[5,6,7,8].
Insertion
sound
|3.
here
that some
confusion
A.
of muffler
and
its
to
which
use
is
in research.
(NR).
measured
This
upstream
Is the difference
and downstream
in sound
of
the
m|_fflsr.
D.
power
Attenuatlcn.
between
quantity
ducts
length
+
i
is the decreas_
two points
is often
where
This
used
is measured
in an aesthetical
in describing
the decrease
in propagating
in sound
[7,8].
29B
system.
absorption
prsesure
level
sou_ld
This
in lined
per
unit
_[[.' .
i i '
.
The
first
three
work. on mufflers
lllumtrated
that
definitions
for automoblle
in Figure
4.
those definitions
msanlngs
are used
engines
It is of
are also
to describe, sound
frequently
and
they
interest
used
with
trausmlssion
in
are
to note
similar
through
walls
or enclosures.
In general,
loss and the
nolsc
since,
except
on the
internal
Impedances
insertion
reduction
for the
the termination
tail pipe).
the
loss,
are
not
transmioslon
impedance
of the
impedance
(radiation
equal
the tormlnatlon
to pc/S
transmission
simply
loss,
(i.e.,
related,
they
source
||owever, if the source
arc
the
(engine)
impedance
and
and
of the
termination
the source
are non-reflecting),
depend
and
then
IL - TL < NR,
and
usually,
NR - TL : 3d[_.
DEVELOPMENT
OF MUFFLER
Although
interference
Qulneke
TIIF,
ORIES
in
the last
of so%_nd propagation
eent_ry
dlsc_ssed
the
through
different
lengih
plpos,theoryof real _se in mufflar
deV_lops_
bosause
until
prior
Impossil_le
d_s
1920's.
to this
to msa,ur_
to the lack
ima_ n_a_
the
time
sound
of meltable
because
of
This
it wa.
d_,Ign
wa_ probably
difficult
pressure
2_9
nolsa
not
p_rtly o
(if not
quantitatively)
microphones
the lo_or
was
and partly
produced
du_
to
by anglnoa.
In 1922
filter
Stewart,
theory
using
1927 Mason
developed
aild Germany
in the
mufflers
a lumped
this
for aircraft
improvenlcnt
his co-workers
wave
[13,14]
propagation
branch
in nlufflcr theory
resonators.
that
in general
weze
good
They
thelr
p_ovided
and chambers
fruqsency,
was
cross
e_i:;t and ons
the cut-off
not
of
when another
for plane
chambers
exceeded
and
and
and
side
foLInd
of transmission
frequency
[12}.
signi-
theory
I_any o_porlmentu
predictions
engines
D_vis
expansion
made
In I_riteiI_
scoured.
then developed
in multiple
In
on designing
cylinder
the 1950_s
_9].
IlO].
work Was conducted
sntil
acoustic
approach
further
Ill| and single
not
developing
par0meter
theory
1930's
floweret it was
ficant
in the USA began
loss
in the pipes
in practice,
Above
this
waves
can
modes
in addition
to plane
tbeir
theoretical
asnumptloss
was
vlola_cd.
When
Davis
a hol_coptn_
log t since
compared
muffler,
they only
with
the
transmlaslon
thin
be
loss
hy saying
tbelr
prediction
measured
about
they
theory.
flow
loss
discu.slon
Of
theory
[5].
ae_
to use
finite
the
which
Davis
insertion
wave
For
made
300
loss,
from their
to explain
effects
must
_'e_son is their
he of pnrtlcnlar
pr_dletlnn.,
to design
very disappoint-
et al trJcd
likely
cnn
aasnmptlons
theory
was
10 dD
amplitude
¢
I
tholr
had e_pcctud
floweret a more
of meen
in Insertion
trlcd
20 dS
that
impoct_nt,
neglect
et al
a mot8
by Davis
importance
eomplst_
et sl in thei_
In
the
the
1950'n
transmission
electric
The
volume
matrices
of
total
product
of
for
(_aeh muffler
s muffler
electrical
theor9
and
insight
four-termlssl
it
is
A,
C,
D which
D,
values
are
stream
or
be
only
be
Several
for
V_rlous
and
Fukuda
the
of
Sullivan
_.
_b
for
has
the
M
flew.
hav(_
since
bear.
also
useful
parameters
Tile parameter
elements
up-
elements
28
and
late
can
[18]
result
1960'_
end
Including
fib.at
Davies
_enson,
Dm£tea
and
301.
of
carrying
of
_i
[15,16,17]
also
gives
whlch
note
(18])
evaluated
et
some
in
method
been
Igarashl
pipe
mlddle
alterNatlve
to
four
to
|[owever,
corrected
Goulbourn,
convenient
system
matrices,
the
Blair,
_n
by
given
worker,
the
equivalent
are
Parrott
(=quati0n
acou:itic
tile muffler
brought
the
matrices
a straight
con-
passive.
[21,22,23].
for
number
know
as
elements
a mean
be
connections
and
br_nsmlsslon
of
quite
t|*o system.
long
linear
al
several
developed
as
muffler
given
Mach
by
tranumlnulon
effects
matrix
affected
downstream
to
to
very
total
The
matrices
characterize
not
assumed
results
necessary
equivalent
is
after
[5].
may
calculate
transmission
is
transmlssios
since
and
element
for
The
and
four-terminal
analog
to
approach
before
electrical
began
using
pressure
related
the
al
This
acoustic
are
et
mufflers
[15,16,17].
velocity
using
Igarasi_i
properties
circuits
venient.
by
late
that
the
a mean
is
in
in
(24].
1970'a
(25,26]
predicting
flow
error.
early
Coates
include
and
(27-32]
muffler
than
porformanee
work _as
Of his
based
on
shock
Inspired
by
Davis's
helicopter
eKhaust
become
muffler
pressures
io acoustic
are
theory
use of the method
of
eon_*uming and
with complex
wlth
engines,
such
between
theory
flow
Davis
_heso
(and its
bonndary
neglect
There
in reglonn
temperature
are
found
to obtain
include
effect
[33] :
for exhaust
between
of disturbed
gradients
flow,
3O2
i
i i
favor
[13| msy
other
mean
possible
agreement
of
can be
mean
trannport),
psrtn
and
gas
with
engines.
belief
better
and
cylinder
little
neglect
flow
system.
gas
incorrect
tall
and, neglect
in the _xhnust
i,
necessary
eseh of which
on ne£ energy
interaction
in dealing
s|n91e
several
experiment,
conditions
of
has
in time
condltloss.
is probably
for
system.
noise
the method
for multlcyllnder
failed
and
exhaust
boundary
that Davis'n
incorrect.
important.
and som@
the
successfully
dlfflcultles
of mufflers
furthermore
why
has
method
involves
can
in the
However,
and
of muffl%rs
masons
method
and
assumed
affects
of the acoustic
an approach
far _hin
manufacturers
have been
expensive
the design
eO
It appesrs
[32].
the failure
by the fact
amplitude
history
thls
than normally
chnracteristlcs
geometries
Although
was caused
finite
spectra
Perbaps
[13] that
alternativo
octave
have been predicted
belief
greater
the pressure-time
Also, one-third
u_eful
much
This
theory.
design
so that
important.
predict
wave
pipe,
and
sound
of mean
In
1970 Alfredflon and
shed new
light on
the acoustic
[33,34,35,36,37].
University
engines.
that
a muffler
acoustic
exhaust
and that
neglected,
finite
provided
included
in the
the mean
flow Mach
theory.
the muffler
effectiveness
cocfflcient
discrepancy
R -_ i.
As a check
Alfredson
i
chamb0r
show, in
later
on
and compared
Flgure
(with flow
with theory
6.
included)
when
occurred
concluded
Th_ good
loss
occur
be
that
as
0.2
ovcrpredicted
for
low
frcquency
this
error
- R2]]
(i)
_nd on f:quatlon
attenuation
of
[35].
agreement
flow was neglected
to be
5.
theory
and exper_msn_
'l)hs
of reflection
(I - M) 2R2]/[1
theory
of
were
M - 0.1 or
computed
his acoustic
it with
to predict
could
for values
in Figure
the
used
e|Lgine
5 to i0 dD or more.
+ M) 2 -
measured
and
flow effects
flow theory
Alfrednon
is plotted
be
effects
approacbed
by
since
transmission
Alfrcdnon
Thin would
i0 lOgl0{[(l
and the result
and the
the zero
(large wavelength).
Error -
could
expan-
on diesel
the mufflers
amplitude
number
pipe,
serious
important
that me_*n gas
in the tall
most
]]as been
theory
sound
of long
used
with
which
of mufflers
commonly
(at least
that
thO radiated
work
work
at Southampton
the design
type mufflers
he has _hown
he studied)
working
considered
Alfredson'u
pubiished
performsnce
Alfrcdoon
mainly
sloe chamber
Davies
an cxpanslon
The result
b_tw_sn
and poor
seem
(i),
theory
agreement
to confirm
303
i
in
that acoustic
in muffler
theory
design
provided
included
in
are very
important.
the model
Another
and
began
the transmission
for
chambers
where
the
use of
of
finite
in reverse-flow
and
pressure
using
and
in the plane
such
formanc_
even
dstail
other
in muffler
dimen_lonal
later
flow
in his
ducts
rather
The use
analysis
in this
The
flow-reverslng
of
impossible,
continuity
of
even
toohnlque
the acoustic
chambers
posslhle
to pr_dlot
region.
Th_ work
ere,s-mode
have
will
since
used
and Omote
ring
a Gulerkln
per-
be described
nlements.
element
concentrated
design.
30¢,
finite
elements
[43] hays used
two-
Crac]gs [44] has
elements,
approach,
finite
than muffler
if not
makes
three-dimsnslonal
mainly
combinations)
paper.
Kagaw_
acoustio
w_s
[30].
of a numerical
[38,39,40,4i,42]
triangulmr
using
to analyze
at discontinuities,
frequency
design.
[45],
Young
is that some
asssmptions
region.
investigators
Ling
elements
thus difficult,
velocity
Crocker
isoparametrio
work
and
element
used
Ling's
i
wave
higher
and
elements
elements
complicated-shaped
in the
of Young
some
of
in 1970 when
finite
are
'l'hescconclusions
muffler_'J (e.g.,
classical
volume
as finite
instances
ond-chambcr/llelmholtz-resonstors
are not axi-syI_etric
to analyze
scoured
in many
of mean flow
necessary.
loss of muffler
the use
end chambers
adequate
the effects
new development
Crocker
reason
is probably
included
model.
while
mean
||owever,
nn propagation
in
in
,J
_ "YI!I__i
:'i,'_,,'
Sido
branch
cans
or
I
bear
'
recently
i
:
re_onatoru
spit chambers),
been
studied
situations,
in thu outer
concentric
the cavity
$ulllvan' 9 work will
In the
the Deed
lumped
parameter
the e_fuct
occur.
of
branch
and Crocksr
expshsion
Previous
phenomenon
parameter
in more
detail
[51] hav_
by Karnopp
[48,49].
otiffness).
later
the
topic
could
mechanism
resnnsnco
al_
range
of
the
the
flow and
by flow.
of
connected
305
an
a
reduced
Kiratn
on side
attennatlon
[52[ has con-
lnoraa_a
s_mplu
and
flow
the poah
Anderson
oauiem
waves.
dependent
of air
that
can
los:J of
be considerably
concluded
rasonator
sound
transmission
was postulated.
frsqnnney
so far is
process.
to be. amplitude
_Iow
on
phenomena
by the flow
st%ldi_d tha Influence
a mean
H_lmholtz
that
touched
Various
b_tween
raduc_d
included
It is claimed
frequency
little
mufflers.
found
s_d
have
elements.
appeared
r_sonators
_hat
design
'H
i
call exist
thin
in muffler
chambers
rfh(_ effect
fundamental
branch
filter
can occu_
is eonsld_rably
oAudad
waves
for
a lumped
can he generated
a feedback
Xtow
to account
extend
flow in
Noise
Frloke
cnn
important
l_teractions
nnd
[46,47]
the resonator.
be described
approach
approach
Another
[50].
3, have
and Crocker
of
aegs like
develo_ments
Graph
this
short
cavity
2 and
as
paper.
Other
that
nee Figures
a)¢ial standing
[lave been unable
(a_suming
by manufacturers
by Sullivan
in practical
theories
(known
An tha
single
to a duct.
side-
Perhaps
the moat
the two
microphone
parties
described
ducted
at
ensblh
method
by
Two flush-mounted
incident
and
between
and
standing
is very
random
wave
much
The
Figure
a.comparison
7 shows
power
tubs end
the pha_e
loss, TL,
parison
reflection
Of a prototype
between
wave ratio
(probe
a third microphone
CLASSICAL
A..
MUFFLE_
Transmlealon
We will
first
was
method
used
waves
good
tile traditional
and
the method
of data
were
7 and 8).
theory
92
and
for
8 shows
experiment
an open
the
th_ claasical
For
downstream
of
end
transmission
m1_fflar with
(SW,).
this
a com-
standing
TL measurements,
the
muffl{|r.
T|{EORY
Line
make
a) sound
pr_peuraa
b}
are no mean
there
and
automobile
tube)
the
between
in Figures
Figure
and
and
Agreement
between
this method
spectra
to measure
coefficient
angle.
are
be used
method
give,
con-
is used
microphones
[only 7 seconds
the plots
noise
is
pro-
in work
spectra
can
la very
used to obtain
for the
i
rapid
[53]
and reflected
loss.
noise
acoustic
and cross
wave
method
tube method
more
recently
White
wall
the incident
transmisalon
two microphone
Ross
of the auto
reflected
to be determined.
impedance
and
Laboratories.
measurements
phase anglo
development
for determining
Seybert
the Herrick
as a source.
used and
important
are
Theor_
som_
small
simplifying
compared
temperature
206
a_eumpti0na|
with
gradlanta
the
or
mean
mean
pressure,
flow
and
For
example
station
then
if there is
1 and
a sudden
the chamber
its
transmission
a sudden
decrease
is known
loss is
Equation
above
(4) is easily
by assuming
x " 0 and
and
given
Equation
expansion
theory
B.
p and
....
waves
chamber.
(Equation
Transfer
An
at the
travollng
Matrix
alternative
volume
be rela£ed
at station
chamber
2,
and
by:
from
area
eqastlnns
changes
occur
the continuity
(4)
(2) and
the pressure
incidunt
and
of
exporlment
prssshre
In
smplltudus
transmitted
i0 gives
of
by
a comparison
from Davis
(3)
nt
_roa discontinuities.
Figure
(4))'and
at
- i/m)2sin2kL].
derived
(4'), Pi and Pt arc
the right
the
+ _Im
th0 sudden
velocity
in area
2,
x - L and by assuming
volume
in area
as an expansion
TL - 10 1og(J_i/Dtl)
TL _ I0 logl0[1
increase
between
et al
Theor_
approach
velocity
V at
is to assume
stations
1 and
that
the pressure
2 in Figure
9 Call
by|
Pl
" AP2
+ BV2'
(5)
V I " Cp 2 + SV 2.
(_)
and
•
Am eleatrlcal
pre.sure
olzs,lt
p In.analogos,
to
an_logy
can
be used
voltage
and
v01t,ms v_locity
m
t
a
t
h
i
308
whirs
the
V
."i:
"
L
to osrront.
Note
that
used
[5].
the
! ':"
This
is known
an alternative
The
four pole
circuit
as the
mobility
element
element
shown
impedance
analogy.
analogy
can
is sometimes
be represented
in Figure
II.
by
If tbe muffler
SeOtlOS in simply a rigid straight pipe of constant
crossnestle,, then from Equations
(2b) and (3b), the pressure
and Volume
velocity
and
at
A and
box"
C,
P2 " p+ °-ikL + P- elkL'
(8)
vI = (slpc)(P
+ - P-),
(9)
(S/pc) (P+ o"ikL
system
assume
Equations
identification
that
thu matrix
Then
(5) and
this
r_snlt
after
some
manip_ilatlon,
(S/po).i
that
P2 _ 0.
tlons
rosuit
for P+/P",
sin kn.
the matrix
Equation
output
Similarly,
that
are
(8) gives
p+/P"
(5) and
(6} give
B - PI/V2
and
found that
B -
(pc/S)
i sin
(7),
kL and
A - cos
N
309
e12kL
D - VI/V 2,
[9) and
D assume
and
and EquaUsing
(10), it la
kL.
(9),
kL and
S and
- -e i2kL
D - cos
-
(8} and
short-circuited
Eq|_ation
and Equations
P+/P-
(7),
to _valuats
terminals
are open
and C - Vl/P2.
and Equation,
Then
for P+/P"
terminals
A - pl/p2
using
To evaluate
(10) gives
it i, found
(I0}
evaluated
technique.
output
(6) givo_
Using
C -
- P" eikL).
A, B, C and D may be
circllIt, or V 2 - 0.
and
2 are:
(7}
parameters
a "black
i and
Pl _ P+ + P''
V2 _
The
stations
this
Substituting
Equations
the_e
(5) and
resultH
for A, B, C and
(6) and writing
D
thcl1_i_l matrix
into
f!orm
gives:
v_j
where
the
length
four
.]Lv_j
p010 conI_t(Lnts (for a straight
pipe
L) are:
_1
Note
thi*t AD
values
of
the
fact
The
matrix
_rcssure
of
.
L|(S/po)sln
- BC _ i,
the
four-pole
that
volume
cos
is a useful
parameters
the system
in Equation
nnd
Thiu
kL
and
check
velocity
at two
the
on the del:ived
is a consequence
obey:_ tile reciprocity
(12) relates
112)
kL
prlncip]e
total
stations
of
[51.
acoustic
in a straight
pipe.
If several
seri_._s, an
complete
system
t
systems
in Fig_ire 12 then
system
is
given
by
the
arc conncctcd
transmis_lion
the prod_*ct of
the
,
310
4
•
matri_
of
in
the
Individu_l
_ h LV2J
DljL__ .2jL_3 ._jLV_j
.i::j
together
matrices;
LVlJ
.
component
|13|
This
matrix
where
formulation
a digital
A, D, C and
elements
as
[*as just
also
be
muffler
computer
D can bc
such
is very
is used.
shown
iv a similar
shapes
(reversing
chambers
manner
resonator
finite
nslng
technique
method
mentioned
and
above
four
pole
straight
pipes
They
for mere
can
complex
and reversing
combinations)
the same
constants
muffler
(12)).
end-chambers
end-chambe_/Holmholtz
particularly
for simple
(sue Eqsatlon
found
element
The
found easily
as expansion
been
convenient
black
by
the
bo)_ Idt:ntificatlon
(with alternatively
P2 " 0 and
V 2 - 0).
EXHAUST
SYSTEM
It will
MODELING
now
be shown that
the
transmission
element
that
muffler
geometry
and
D) and
elements
will
unaffected
or
source
be shown
source
and
predict
the
load
source
easily
'
and
transmission
design,
On
loss
Finally
n knowledge
ions of
thsorstleally
A,
the
,, C
the other
of th_
not only
of
but also
tall
and is osrtalnly
llow_vQr inset*los
to
pips
th0 source
of
the
pr_sst_re or volume
is the
]*and, it
by the
if it is deelrcd
a muffler
311
ozzly of
is affected
level.outside
- either
muffler
of subs|',guent muffler
load Impedance
strength
predicted
in muffler
the insertion
to h_ve
passive
constants
10ad impedances.
se*_nd presssru
(engine)
Th_
four-termlnal
impedances.
impedance
linear
loss is a property
by connection
or
that
it is necessary
(englns)
|i.e.,
for any
velocity.
q*_entity most
of
guldenca
loss or a prcdietlon
of
tile sound
much
more
sow
pressure
useful
to tile muffler
Tranmniaoion
Ths
tile tall
designer
pipe
and
valoclty
source
same
number
inl_t
syotem
englne-muffler-termlnation
derlvatlo_a
electric
model
of TL
circuit
in Figure
(althsugh
result).
theoe
are
For
the
pipes
So'are
13b
gradient
transmission
_mplltl|des
the
the
p_pe
non-reflectlfl_
Figure
easily
and
incident
d_tormlncd
(Zr - pc/S O ).
13b
(see Equations
Pl
be
modeled
The
used
source
in the
model
mesn-flo_
areas
of
there
and
h'_l .sd Ip_'l are _eeded.
IP_I iS mos_
and Erom
equal
De
Maeh
is no mean
To dotermlne
tranmnittcd
pre0ssro
The _rans_,itted
by
Thus
glvos
the muffler
In tile mtlfflor syst_m.
loss,
sure
From
will
pressure
simplicity,
assumed
may
[19,20,24,5,I].
M m 0, the cross-sectional
tomperatL|ro
m_klng
the
pro.-
tall
p_ _ O.
(2a) and
(3e))_
- p_ + p[,
(14)
vI ,. (solpe) (p_"- p[),
(is)
va - (so/p_)p _,
¢16)
Equation
(II) *
+ 6, " "
+ p (olpo),
(solp_) (p_ .- p_) ,, e p_ + D p_(Sol0e).
From tha defln;i, tlon
in Flg-re
4b_
Jx_
i:
arc
Loss
as an equivalent
the
from
discussed.
A.
the
radiated
tiT)
(z.)
,_,'_,_'i
_.,_ _,, ,%_. _, -.
",L_
.,._
i,:,,_.:
__,L-,•¸ ,
_
_9 1__':_b:.", ,/.
_pIL
_
. ,kl._
¸ ,. •,
:_ 20
'PL -
10
Thcn eliminating
subt]titutlng
p_
into
Egustlom
w_o
C s.d D have
[40].
used
sllgbly
the mean
temperature,
result
note
of volume
different
a result
to
that
+ DI/2).
that obtaleed
in
velocity
area
so A, I],
Sullivan
to Equation
cross-sectlonal
by
(40] particle
and
definitions.
similar
(20)
(20)
[24]
in which
and mean
flow
in
1 and 2 are different.
transmission
ineo_venlent
to
an anechoic
o_ absorbent
to predict
With
tha
by measuring
microphone
when
probe
hbo
source
standing
packing
tube
[15,41]
situation
with
13)
the mlcrophone
probe
envlronmsntal
condltlone
Alternatively
the transmi_elon
tuba
of high
temperature
loss
m
m
313
carl
cnabllng
plp_,
using
a
process).
in th0
engine
is placed
an
Is a loudspeaker,
is determined
an automobll_
It
Ip l c, n a so
in the exhaust
_oss
but
ears
from
(txlthough it lfl n laborious
if (:he transmission
"roal-llfe"
(in Figure
wave
some
termination
e sured, Irecti 'n,o
, uantit
be determined
source,
horn
TL i:_ convenient
experimentally.
to construct
absurhently'llned
However
loss
to measure
iS possible
:
(19)
(10) and
+ C/(So/PC)
Except
instead
derived
The
'
2.
(19) gives:
+ B(So/0C)
has also
pipes
Ip_j2/Ip_J
(17) and
(20) is a similar
and Crocker
veloclty
in Equations
Equation
_L _ 20 io_10[IA
Young
loglo
lOglo
as
under
a
severe
_nd moisture
be measured
using
condsnaatloi:
two
xnlcrophones
Scybert
and
Ross
termination
stand
is
tbe
and
a
is
B.
of
[53).
used
high
interest
source
instead
it,
the
Iesertion
a
inu[_t be
of
special
Of
loss
Using
Zr
pipe
radiation
are
tall
which
Figure
pipe
13b
to
with-
practical
an
is
by
anechoic
design
more
with
suggested
engine
discussed
again
as
next.
gives:
- V e - pl/Ze,
V 2 _
Z u and
nlueh
to measure
insertion
V1
as
if
easier
Loss.
tube
However
temperature.
much
where
a probe
the
(21)
p2/Zr,
(22)
engine
impedance,
internsl
impedance
respectively.
Then
from
and
tall
Equation
(II):
.pl
S_|bstltutlng
and
for
combinln
_
AP2
+ Bp2/Z
r,
(23)
V 1 -
CP2
+ DP2/Z
r.
(24)
V 1 from
9 Equation,
Equation
(23)
and
(21)
(24)
into
to
Equation
_llmlnate
(24)
Pl
9ivesl
P2
If
B e,
M ZeZrVe/(AZr
a different
C t and
prensuro
p_
muffler
D'
is
now
+ B + CZe?. r +
with
connected
four-termlnal
to
the
DZe).
(25)
parameters
sngin_t
a new
r_nults!
p_ - Ze_rVe/(a'zr+ _' ,t,
C'ZeZr + D'Z ).
i
!,
A',
31it
(26)
Thus
i
t
P_22 AZr + D + CZoZ r + DZ e
P2 " A-_Zr + D' + c'Z_Z r + b'7_e"
This
result
is similar
If p_ is measured
with
(in wavelengths)
to that
no muffler
e_haust
obtained
in place
plpntthen
(27)
by Sullivan
and only
[24].
a short
A' _ D' _ i, and
B' - C' _ 0.
Then
p_
P2
This
result
. AZ r + D + CZeZ r 4. DZ e
_e + Zr
ia elmilar
IL - 20 logl0Ip_/p2
or
(28) that
impedance
,bs_idea
the
Several
of mufflers
assumed
englp¢
[55).
values
of
alnoe
In prediction
Diseusslon
on
_n e later
msetlo_.
XF the
the
englne
olther
IL depends
the tail
h_vQ
on
engine
hays
Younq'a
insertion
Young
had
(e.g.,
mcas|zred values
impedance,
of th@ muffler.
normally
Impedance
(27)
the internal
radiation
the
e.g.,
Slneo
Eqtlatlon
both
pipe
predicted
they have
[20].
in
characteristics
recently..
bn dlac,ssed
from
on onglnes,
|Xowever
available'until
m
m
and
workern
installed
p_/S O or -),
w_ll
the TL,
the tranemls_ion
itself.
Davies
I it is seen
unlike
of
to that obtained
(2U)
loss
(IL)
[40] and
to rely
on
Z o - O,
not
results
become
for IL,
[40],
later,
of
inoertlen
problems
lo_es
Zr must
of eut_matlng
and radlatlos
also
Ze and
Impedances
Zr
be known.
follows
are assumed
to
i
I
bS
Z_ -
I
Z r - po/So,
then Equation
p
(2fl) becomes!
.
i
I i
p_
A(pc/S o) + n + C(_e/So)2
P2
+ D(pc/S o)
2pC/So
,
(29)
and
zL- 20ioglolp/p21,
IL
= 20 log10{IA
a result
identical
the general
not equal
loss
ease
it
can
loss
source
(transmission
and tail
Presssre
to muffler
loss
when
loss
the
termination
The
theoretically
tranemlssion
the travelling
in mufflers
insertlon
pc/S o •
or
with
is
impedances
Impedance
than
lladlated From
of
this
Wave
and
the
solutions
ezhaest
or Innertlen
p_cssure
mines
the acceptability
(25), shows
that if
V_,
and muffler
ara known,
level
engine
is th_
probably
a knowledge
After
volume
Zo,
316
of
either
finally
velocity
impOrtrans-
deter_quation
so_rco
resistance
parameters
amplltsde
more
the radiated
Examlnlng
radiation
(fourpole)
pressure
all,
which
a mllffler.
impedance
the total
is of
quantity
the engine
four-terminal
then
than
loss.
of
Tall .Pi2__
qllantity
designers
sound
strength
delnonfltrates
intuitively
difficult
llne theory)
A prediction
mission
cxcept
(30)
pipes.
Sound
tance
This
acoustic
by. studylng
DJ/2};
trsnnmission
and
be reached
in more
matrl){ theory)
(20).
the muffler
to the characteristic
(althongh
C.
that
with
same conclusion
C/(So/Pc)+
to Equation
to the insertlun
is'measured
equal
+ n(So/PC)+
Zr
A, B, C and
(and phase}
D
at
the end of
fairly
simple
amplitude
m_ttcr
to calculate
from
The method
the
transmitte.d
in
P2 can
IPrI at distance
[33,34,36_.
tion
tile tall plpe
tail pipe
out
of
the dive.rging
ths net
the tail pipe
wave
2w a2'(_p_}2/202e2)([l
t|]s tail
ill to assume
so that
spherical
It is a
the. radiate.d pre.s_ure.
r from
used
be calculated.
pipe outlot
monopole, radia-
acoustic
inten,lty
is e.qual to the intensity
at radius
+ M) 2 -
r.
This
give.s:
(1 - M) 2_2 (M) }
- 4n r21prI2/2_oCo
where, n
flection
mean
is the tall
coefflele.nt
flow.
the
tall
station
pips radius# and
(dcp0ndent
Subscript
pips.
From
on Much
the tall plp_
numbsr)
2 refe_'s to conditions
EqsNtlons
(2a) and
of
Just
at tbo
the
inside
(3c), at any
tail
pipe
(_e/So)V,
(32)
exit|
P2 A V.Z_r"
Thus,
st
the
tall pip_
P2
end
rs-
in ths m_*ffl_r:
2p + - I_+
and
R(M)
(31)
aubstitL1ting
exit,
- 2p_l[l
Equation
+
from
{33)
Equations
(32) end
(0C/So)IZ r]
(34) into
(33);
(34)
(25) giv@s|
p_ - VeZe(Z
r + _c/So)/2[az
r + _ + czezr + DZe}.
(_5)
1
.'117
i
•
J
_'aklng the
into
modulus
Equation
Iprl in
engine
(35) and
the source
pipe
volume
radiation
parameters,
coefficient
R(M)
tile mean-flow
A.
|{ADIATIO_N IMPEDANCE
Early
of
lh the
R was
on mufflers
tile refleetlon
reflection
discusses
past
about
and
some,
published
a rigorous,
reflected
wave
solution
mean
coefficient
plp_
from
assumes
flow.
uslng
motivation
In
in
IMPEDANCE
hampered
the
AND
st
by s lack
SOURCE
the magnitude
and
an _ll_ng=rl
wnv_
phase
Levlne
phase
the engine
angl@
exhaust
to determine
a significant
coefficient
and
phase
results
and
Schwingnr
and
0 of waves
in an engine
effect
on
of
r_sults
the zero
Levlne'and
are
l|ignel.
and an
given
the
The
ti_e reflection
flow
{56]
of
measured
if a mean
been
ti_e
in the pipe
as the source
pipe.
coefficient
pipe.
calculr,ted by Levin_
experimental
of
de_ivation
circular
propagatlon
AlfEsdson
know-
have
ass_:ming tl]e reflection
Is* 1948,
of
the end of tile tail
lengti_y theoretical
1970,
theoretical
was
one).
plan_
R and
wa_
Alfredson'e
Zr,
reflection
Macil number
assumptions
had
the
pipe
[33], various
temperature
Both
Ze and
tail
r ENGINE
of waves
(some workeru
zero
the
Radi_tipn
work
As Alfredeon
made
Ve,
M.
_Ta__ilPipe
ledge
velocity,
the
it
the pressure
impedances,
fourpole
and
substitutinrJ
p_ and gives
tile muffler
_'AII°PIPE
STI{I':NG_'i{
L
of
tail
tail pipe,
i
Equation
(31) eliminates
terms
and
of
no
t_il
Th(l
elevated
flow
reflection
and Schwlnger.
Schwlnger
and
in Figure
14.
Alredeon's
centage
increase
no change
to
those
0 can
impedance
Z r used
tall pips
to determine
yields
V 2 " (So/P2C 2) (p_ - p_)
B.
En_n_
recently,
completely
and Source
vmlues
speculative.
by various
loss
calculations.
Other
mental
different
arrangements.
to constant
(voltage)
volume
sources,
a load
shown
impedance,
to Figllres 15a
at
Zrl
- Re|0).
impedance
of Ze of
workers
(36)
hay8
trlcd
idealized
and lSb 319
respcctlv_ly.
experi-
preset*re
the ml*ffler and
13 are
then Figures
to
0, correspond
and constant
Ssppose
in Figure
and .,.
in ml_king insertion
in their
(current)
|lave been
0, pe/S
of z e - _ and
respectively,
together
reduce
velocity
Streeqth
engine
values
velocity
ImpedanQos
(35)].
)(I - Re|0),
experimenters
Valses
termlnatlon
as
of
Values
been assumed
these
pressure
impednnce
- p_(So/P2o2
have
slmulata
radiation
tail
radiation.
(25)and
(P2c2/$_ (I + Rci0)/(l
Impedance
Until
i
-
engine
L'esults for
pipe
sound
(28)or
virtually
+ ,_eiO),
P2 " P_ + P2 " p_(1
¢, Zr - P2/V2
the tail
and volume
the
and
in a typical
loss or
(27) and
a 3 to 5 per-
and temperature
and Schwinger's
the pressure
exit
coefficient
found
in insertion
of
show only
as the flow
Levlnc
[Equations
The ratio
the
or
be used
predictlon 0
anglo,
conditlonu
Alfrndson'o
R and
results
in the reflection
in tile phase
increase
Either
experimental
lumped
13b and
13e
pipe.
For
and
the volume
if the
volume
this
internal
velocity
impedance
is known
impedance
pressur_
is supplied
impedance
Note
constant
sources
constant
volume
equivalent
er_
well
0, pe/S
values
must
vary
Thorn
with
working
a mathematical
cnglno
or _.
model
connected
passages
of engine
approaches
as
such,
model.
sonreos
ranges.
Some
directly
Mutyala
of. a slngl.-cyllnder
and volumes
ar_
treated
3_0
approxi-
approach
and
to model
expanslon
[57]}.
it could
close
are
which
Impadane_
one
hays
since
it
Open.
the
using
englns
the con-
and Boedol
the llorrlck Laboratories,
to a elmple
These
sources
impedance
porta
Without
impedance
engine
also).
that
(see, _.g.,
frequency
_xhaust
throe
ak
that
of
prensur..e
model,
voltngo
However,
tho meaning
flnlts
pressur_
circuits
if the
indepondent
in either
and
source.
acoustic
as a constant
and constant
nnllkcly
time as
A constant
it remains
hays
used
two-ltroka
chamber
aa lumped
its
I_hen Ze ", _,
+ Z£) and
in either
of
veloclt_
terminals
obtained
current
eharaeterlstloe.
of engln_
(5B,5_9],
not
in certain
are at least
source
is known
In.electrical
either
quQntloned
loud
{providod
velocity
eour,e
these
cept
are
to constant
even
The
to the
Independent
volume
"_ Pc"
+ Z£)
A co_sl_._n_
flnlte).
_ PcZ£/(Ze
if Ze - pc/S
It Is of
mates
of
that
known
it remains
Pl
Zo -_ 0 this source
source.
to tile load,
Z e -_ O, Pl
value
V I : VeZe/(Ze
Ze -* _, V 1 ., V e.
as a constant
source,
internal
When
i
impedance
(provided
the pressure
of the
source,
is supplied
value,
source
For
velocity
muffler.
paremetors
and kinematic,
used.
Good
obtained
thermodynamic
agreement
for
the
Galaitsls
to measure
magnetic
in
an
ware
engine
pure
able
low RPM
tube
the
Impedance
|61] .ha, al,o
used
(and source
is well
strength}
Using
_ath_iya
this method
theoretically
they
]lowever, at
At
high RPM
frequency.
Ross
technique.
is the
aco_xstlcs.
waves
impedance.
to the dot_rmlnatlon
in electricity
approach
an elnctro-
_ngino
internal
at higher
a _imilar
approach
known
pe/S
are
was
an empirical
to a running
fluctuated.
approached
experiment
by mea'_uring standing
the engine
th_ impedance
A third
and
equations
noise.
directly.
connected
to determine
and
|'60[ have used
impedance
source
theory
exhaust
Bsnd_r
tone
impedance
between
radiated
and
and man|* balance
of
two
load method.
but
haft been
and MunJal
but
tried
recently
have
impedance
This m_thod
little
[.54] have
apparently
engine
in
discu:_snd
yet to try
it
in practice.
Using
15b)
th_ pressur_
and-two
equatlone
dlffer_nt
source
known
representation
loads Z£
and Z_,
3
Pe
in
Z'e "
£quation_
(37)
(Pl " PI)I(P_/_
i,
321
1
(sec
Figure
two simultnn_o_s
are obtmlned_
Pl " PSZK/.(Ze + Z_) 0
Eliminating
[54]
and
(3'/)
(3B)
given_
" PI/Zg )"
(39)
Substitution
source
of
strength
two different
in back
and
Pl
inside
from
In order
the tall pips
Pl in
(31) and
(34).
Egolf
a hearing
of
the mothod.
aid.
A program
automobil,
since
Element
the load
and
radiation
tile necessity
the
exhaust
tile sosnd
this can
pipe
Sullivan
gas
DESIGN
of research
on
been
radiated
to the
such as
load method
in the design
the limitations
AT IIERRICK LABORATORIES
the acouatlc
conducted
performance
of
at llerrlck l,aboratorlss
pepe_
provides
e osrtaln
of
[38,_9,40,41,42]
analysis
it hasbeen
behevlor
normally
;_nalysi.,
elem@nt
a sufficient
muffler
based on
frequency
that
limit
acoustic
theoretloal
elements.
the plans
wore
tho
in muffle.r design.
assumed
are
is hot) it
related
[24] discusses
impedances,
impedance)
pressure
bm
change
to measure
by equations
two
MUFFLER
and Crocker
finite
{13,14]
the
(presumably)
this
m|_fflora ha,
Young
this
is little
pipe
using
1970.
Finite
usa
since
the straight
WORK ON
there
so that
(where
[62] has used
of
suggest
to measure
Pr
(38) now gives the
Munjal
to remove
the tall pips
praasure
and
of straight
be possible
RESEARCH
pipes
and so that
(comprised
(37) or
Kathuriyn
length
known.
should
Pc'
pressure
Z_
well
Zc in Equation
wav_
This
322 _
So far in
filter
theory
explanation
filter
assumption.
is reached
first to
(known
theory
However
as
for
is
when
the cl_t-0f_
Z£
frequency),
wave
the filter
theory.
(This cut-off
to the pipe
clement
and
or
shape
to
methods
were
in
used
acoustic
over
The
that
of
function
an approximate
At
the
volume
A, B,
b,forc
.imilar
Into
n number
of
velocity
C nnd
and after
mannBr
_ha matrix
to that
ed
the
element
four
[38].
The
surfac0
the normal
area
fi_id
is essentially
element
is
elements).
pressure
pole
volume
assuming
and
parameters
voloolt M
are obtained
_ro _itorn.taly
323
!;
acoustic
of a
the Langranglan
(flnlt_
nbov_
the
in
pressure
muffler
and
of
here.
the other
approach
The
the pressure
terminals
which
by making
subreglons
S.
Tb_
The
described
area
and
this
approach.
the muffler
output
or _hort-clrc
Thus
det_rmlned.
D relating
instead
is described
over
is prescribed.
of
complicated
is composed
a surface
the elements
are
element
one area
[38].
energy
corners
problem
is prescribed
stntlonary
of
was
approach, varlational
approach
is eolved
assumptions
method
not be giver* in detail
gas with
element
wave
to apply.
loss
the
the muffler
the pressur_
proportional
if the muffler
plane
a numerical
In this
two parte_
the muffler
simple
transmission
will
displacement
which
divided
and
to plane
Is usually
difficult
work
tl_eoretleal
V of p_rf_ct
Is composed
are
according
In addition,
the
to formulate
[38-42]
It la assumed
velnme
the
elements.
equation.
detail
diameter.)
conditions
predict
muffler
wave
frequency
and Crocker_s
shaped
to behave
is complicated,
In Young
in
chamber
the boundary
produced
ceases
in a
that
open-clrcultod
S
At
and
the
corners
volume
velocity
meters
A,
before
and
similar
B,
C,
are
the
to
elements
the
muffler
are
order
computer
to
check
program,
the
it
wtxu first
expansion
chamber
used
are
chamber
24
was
8
the
chamber
finite
elements
with
nodal
three
17
shows
16
by
17
that:abov_
velocity
in
a
that
or
the
matrix
short-
an
the
24
shows
the
element
elements
if00
was
points,
i0
simple
'fhe
inches
(0.25
m)
only
elements.
The
second
firnt
had
16
elements
had
The
third
had
points.
trnosmlssion
models
[TL},
io_
and
by
(see
Of
elements
IIZ,
16a.
finite
16b).
chamber
is
the
symmetrlcnl,
the
Figure
convergence
loan
and
studied.
expansion
about
In) long
and
classical
of
Figure
models
[eno
Eight
In
worn
the
dimensions
with
nodal
rapid
The
approach
to
represented
38
finlto
transmission
16 or
paL's-
volume
assuming
applied
chamber
nodal
points
approxJmatlon.
the
WaS
with
for
the
element
elements
theory
pole
obtained
element
given
(0.20
Sinc_
Figure
the
inches
diameter.
28
are
pressure
open-circuited
finite
[40].
with
and
above
alternately
ease
8
pressure
described
chamber
Three
Tile four
element
expansion
half
acoustic
[30].
In
in
the
determined.
that
terminals
circuited
the
D relating
after
manner
output
of
are
the
the
the
classical
(4)).
finite
,.'lemon|
Inauffielsnt
the
same.
classical
by
Equation
the
although
about
predletud
TL
to
Figure
predict
predicted
Note,
theory
however,
and
the
S
1
3ff4:
I
/.
flnltc
element
frequency
plans
than 0.8
waves,
can
However,
the
predicts
the plane
and higher
eniat
classical
used
wave
to predict
flow
12elmholtz
resonator
comprised
of combinations
and
the
with
wave
ant
nsnd to
in
amplitude
a single
flew
on
such
3), end
pipes,
examined
is shown
loan
Figure
known
as
chamber
mufflers
end
(I).
sad minims
The
microphone
supplled
the
and
(J) was measured
wave
of
standing
transmitted
the
tsrmlnntlon
to the
wave
WaS determined
tile ntandlng
(M) since
by the anechoic
c0t*Id be
tone signal
Using
of the incident
on
18.
An acoustic
a pure
;_rohe tube
in Figure
was based
19.
section
froqL_enclca.
air
chambers
straight
bhs tent
at dlffsrent
moan
could
successfully
finally
supply
the maxima
minlmlzed
program
and
o_ t_ansmlsnion
wsv_
were
(,I)) only
(see Flgurn
of
by measurlng
,_n_(i by
losn
comhlnatlon,
m6thod,
(22) was
the
chamber.
element
used to examin_
end chamber
the microphone
theory
in addition
up to two 22ellnholtz resonators.
measurement
_tandlng
finite
end chambers
A typical
drlvnr
modes,
the expsnaion
transmiasios
reversing
chambers
in
the
it was now
atandlng
this
performance.
chambers,
The
Above
ti]eory (Equation
22eying shown tbat
be
diverge.
the chamber-dlameter-to-wavelength-ratio
lefts
become_
to
TL predictions
wave
wave
was
doter-
r_fleotlons
(L).
plennm
A steady
chamber
m
(G) and was
I
'
loss
used
to invsstlgate
In some experiments.
925
flow
offeetn
on
transmlnslon
Figures
20
transmission
loss
chambers,
(33.5
with
m/s).
The
and
first
of
show
two
and
without
Neither
end
chamber
ths second
21
ban
sldv-ln
the
predicted
different
nllape
a mean
air
chamber
side-in
center-out
agr0emont
good
that
appear
velocity
(Mash number)
used.
to act as a side-branch
The
theory
developed
paramotrle
study
and
locations
The
results
of inlet,
22 find 23
transmission
loss
of which
end
chambers
llns)
are
and
have
shown.
The
and 21, exespt
_t
should
The
without
prsdictlons
charahsr and
U_ed,
SI-SO
tubes.
that here
that
and
in
is
the mean
volume
flow
al)pCared
{Figure
21).
a theorstical
as dimensions,
tubes
were
changed.
Both
canon
pans
worn made
tub_s
two-dlm,nsional
llne)
_Imilar
to
and
the third dlmellslon
¢
Figures
_re presnnt.
points
wore
attached.
bot:h tile end
f_alt(_ _lemento
finite
tile
(solid
(broken
rfi0onatorn
into
when
attached
are
by dividing
end chambers
the canon
the expsrlmentsl
flow but with
and me,soured
and SI-CO
are no resonators
the rsson_to_"
AlthoucJh only
pass
llolmholtz resonators
be noted
It
chamber
ths pre,dlcted
no-resonator
20
medmursd
show
pans
whe,n thsre
at
tube.
141].
of similar
have
pa'Jn
tubes
to conduct
and
ft/nee
theory
end chambers
outlet
Is
with
of the
then used
a
tub_s.
tile SI-C0
on r_verslng
are given
Figures
both
was
ll0
had
small
Part
with
of
end
(SI-SO)
(SI-CO)
that experilnental
flow effects
flow
side-out
measured
rever'_ing
examined
obssrved
_nd
and
ol_ments
the elliptical
141],
were
cross-
1Z6
i
•
:.
o
•
.
,=
.---
ml i
sectional
.hapo
tha elements
It is
were
allowed
corroepondlng
noted
in Figures
in the
frequency
the value
of
quency
356
[mass-sprlng)
must
De
produced
_nd
[42].
mode
with
resonance
using lumped
The higher
by a higher
well
fre-
parameter
frequency
resonance
pe_k
cau_led by
the l|elmholtz rnsonatoru
and
the
chambers.
Figure
neck
is
24 shows
Figures
26 and
loss
for
The pr_dlct.lons
wore
pole parameters
of
of
pipes
method
muffler
straight
discussed
in the USA
branoh
that at
of
important
27 show
made
except
different
chamber
using
that
at
the
was
that
Of 32 m/s)
there
systems
Eq**atl0n
reveres
cross
low
combinations.
the predicted
with
(13)).
_hown. in Fig_*re_ 25,
_onaontrle.resonators
leapt
muffler
and measurnd
four
those
the matrix multiplication
(see
sutomoDile
resonator
in determining
th0 predicted
by combining
end
earlier
factor
of the
[42].
three
the
combinations
are typical
an
the poDltioning
.los, curve
25,
trsnsmissloa
th_
that
theoretically
the transmission
I
for the
resonator
between
The first
350 llzagreed
||= calculated
theory
interactions
at
of
attcnuatlon.
loss curves.
peak
of .a l[elmholtz
sharp
of
130-42].
23 that the addition
produces
tranDmloslon
resonance
the mass
to their thickness
22 and
the |lelmholt_. resonators
pe_k s
for by varying
Mach
26 and
fl0w mufflers
flow
are
The
al_ments
nbs0nt.
number
and
27
_sed
slde
Xt was
shown
t_,ed (flow velocity
very
littl, difference
327
in the
transmission
effects
ing
lees measured
may
De more important
to higher
a greater
englne
effect
DREDIC'rION
OF CONCBNTRIC
loss
known
as
"spit
These
resonators
frequency
chambers"
attenuation
rigld
cylindrical
tube,
thus
Crocker
to derive
the
the cavlty
both
short
primary
axlal
0
and the
modal
28 and
and
_
(sometimes
(See Figure
used
to provide
higher
of perforated
cavity.
Sullivan
vohlme
accounted
cavity
via
3).
by [)lacing a
control
tube
(i)
tile tranu-
examined
CallS",
which
frequency
fl of
speed
then
the
cavity
short
two peaks.
resonators
frequency
the
of
29 f_how the
rssonanc_
.iS
loss
have
a length
in ths
to have
and
the
and
nppro:leb
for
tile
the coupling
impedance
of
perforate.
Figures
the
motion
(correspond-
BIXANCB RESONATORS
constructed
model
rates
(see Equation
resonators
all enpartlonud
a th_orotlcal
wave
flow
sound
"bean
a one-lilmenslonal
longitudinal
between
is expected
shell around
forming
used
Also
arc often
are
Flow
flow
tube
or
flow.
at higher
[46,47]
concentric
which
without
TUB_I SIDE
and Crocker
Of
or
on the radiated
5).
Sullivan
,
loads).
and Figure
mission
with
of
nol*.d
is said
resonators
_ho
and
[46,47].
fr is
loss
l_onn_. The.
first r_sonanc_
32_
20) is
po_k
than
for
resonators
thc.flrst
(fl " c/2_)
If
£ tile length.
(Figure
ioss
In short
the cavity,
t:o bu
I
tran_*misslon
where
fr _ fl'
transmisslon
chsractorlzed
results
from
the
by
coupling
and
its
from
in
the
center
frequency
the
28,
the
to
The
axial
performance
of
dependcut
libra
on
k O is
the
th_
wave
fo'
conductivity,
the
_n
is
c
resonator
above
29
liore
the
first
standing
is
the
wave
the
transmiu:
several
other
modal
5.0%,
from
0.5_
fr and
the
merged
loss
ance
frequencies.
to
was
loss
fl =
c/2£.
is
=
/_.
reso_ancc
and
'on
and
mm
• hs
not
27r fo/c
l{clmholtz
aaial
ten
66.7
INSERTION
but
resonators
sound,
primary
length
mlsslo,
frequency
k° _
and
tha
of
gradually
than
frequency
wlterd
of
less
related
tube
the
llowever
iN
The
modal
volume
of
quency
is
of
effect
_ncrease, d
28
ko£
speed
fo
27_.
concentric
tbeoretlcal
constant
approximately
[46,47].
by
cavity
cavity
C,
V and
length
of
rospeetively.
Figure
_hown.
fr
ntamber
£ are
concentric
frequency
parameter
frequency
the
equation
ill Figure
first
the
c_Llculated
llolmholtz
peak
the
with
be
frequency
second
equal
can
llelmholtz
fundamental
tbo
tube
fr
brunch
Figure
tile
of
of
changing
first
so
that
modal
a wldu
a
long
frequency
resgnator
fr
cavity
Jongltudlnal
P'
30
urn
uho_:g
porosity
of
a=J the
porosity
tile primary
axial
to p_ovids
the
of
the
resonator
is
resonance
frequency
]land
a
of
high
occurs
fre-
fl are
trana-
[46,47],
LOSS
eff_ot
investigated
of
souro_
impedsnc_
theoretically
by
329
on
Young
insertion
[3g].
loss
Soms
results
are
shown
in Figures
seen
that there
loss
curves
source
when
for the
impedances
investigated:
the prediction
is made
averaged
on
filter)
are much
31 and
that
32 are different
the fact
is chosen.
that
p_sees
curves.
through
In Figure
insertion
standing
loss
pipe_
in
Z I = 0,
in
pc/S,
the vertical
figures
scales
s different
the
32, the
hills
the lengths
of
predictions
in
Figures
engine
loss
in the
caused
straight
is
loor_
the insertion
to be
firing
interest
and valley,
thought
is
25 llz
transmission
the l,iddle of
_,
loss
lose
of eonuldcrablb
in the muffler
and
frequencies.
insertion
and that
ct*rves are
waves
different
(with a theoretical
Also
in both
three
is
insertion
tl_at'if the insertloa
bssiu
Note
31 it
between
for discrete
the differences
less.
frequency
curve
32 shows
an energy
that
Is Figure
is a lat'ge difference
for a muffler
floweret Figure
tail)
31 and 32.
by
(exhaust
end
systems.
CONCLUSIONS
This paper
ment of
theory
has
te predict
mufflers
(silencers)
Research
conducted
reviewed
in a
Xt seems
can predict
reviewed
used
at
little
/
'
,
the historical
the acosetlc
on Intcrnsl
performance
combustion
llerrlck l,_boratories
inore
that theory
developof
engines.
ht_s been
detail.
ha, now
fai'rlM sccuratoly
of muffl.ere partlculsrly
..
briefly
when
the
been
dcveloped
transmi.slen
leud_posker
330
which
lose
(TL)
(or _cou_tic
_6__ _ _ _
"_
_ _
'"I-L'_ •_,,
_
,
_
_t
_
_
driver)
type
to predlcb
is
sources
the
installed
and
shown
to predict
pipe
56],
has
the
bsen
been
less
loss,
averaging
It would
bench
test
insertion
driver
flow
could
sad
be
predictions
effects
throu@h
_nsertlon
experimental
for
has only
Young
has
narrow
it
radiation
of a
some
time
recently
(engine)
shown
impedance
bmnd
required
mufflers,
used.
be-
predictions
and
some
not-up
may
fre-
be los,
than
provided
loss
and/or
affects
important
in insortion
could
could
s quick
an acoustic
gradient
be included
ths mufflnr
los_
of
llowsvor, in this
bs m_asured
_arrow
required,
ca_o,
would
be
in transloss
pro-
by supplying
from a fan or
']Jl
,.
then
and
the purposes
temperature
loss
flow
for
of different
Flow
tile muffler.
Impedance
the. transmission
however,
dictions.
not
that
Tbsss,
mlsslon
source.
are net
rate*_
can .be tol_rstud.
seem
loss
effects
a mean
IL,
to compare
source
lest.
provided
it
if it is desired
(engine)
However
important,
in
theoretically
Of engluns
when
flow
of a muffler,
[391 tllat source
of insertion
quency
that
loss
known
[60,61].
theoretically
exist
the radiation
impedance
measured
comes
gradients
tile soureu
Although
difficult
loss of a muffler
theoretically
to know
Impedance..
It in more
and high mean
tile insertion
is necessary
tall
engine
temperature
It was
used.
transmission
on an
severe
are
blower
with
band results
such
aro
an
Because
ilnpedance)
acoustic
flow,
effects
used
and
with
it and
known
it,sort|on
Thus
loss
should
the mean
provided
some
it may
way
a "standard"
each
is not
freqsency
be almost
real
as easy
sourcetthan
to try
to make
an acoustic
driver
and
to test
vastly
could
be
measured
Tile comparisons
to other
engines
different
is used.
to use an
an artificial
fan or blower
a muffler
engine
other.
averaging
in muffler
mufflers
be applicable
flow
(and engine
to be important
of different
coltlpured with
mufflers
gradient
the only
engine.
provided
ease
are
performance,
is on a real
between
temperature
and
In any
engine
as a
source
from
combination.
ACKNOWLEDGMENTS
Thin
paper
is based
in part
in the NOISI".-CON 97 Proceedings
•
previously
of
in some other
tile paper
are new.
on a paper
and on
papers,
Much
of
the
Laboratories
which
was
was
by' contracts
from Arvin
Indiana.
_
r
results
332
sections
rose.arch work
described
in
Industrles,
appeared
presented
floweret, some
at llerrlck
fnnded
which
conducted
this paper
Coltzmbun,
I!
I
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Thesis,
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i
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357
;,
SHOCK-TUBE
METHODS
PULSES
FOR
OF SMALL
B.
SIMULATING
EX|LAUST
]'IIGI'[-PERFOI_.MANCE
SLurtevant
and
J.
PRESSURE
ENGINES
1..2. Craig
California
In_tlLute
of Tcchnology
Paaadcna,
California
ABSTEACT
The uniquaa,pcct_
pulaau
that
occnr
of ntvop-frontcd,
in the cxhauat
_s/atcm_*
i'ntarnal-combuntioncnginaa
ara
and
that
expnrlmental
ana.lyzl_g.uch
tnchniquo,
_xhanmt
of wav©.-diffracdon
incident
w_v,,
i'armanc¢
radiated
the cxhauat
It la
are
of ,tropic
noiae
that
par.refinance
_nginn,
_teop-frnnted
th,_ axhanat
dynamic0
apccialanalytical
for taating,
wav©n
/or
important
atgnificantly
in thonn
accurately
_imt*lnting
Two cxarnpl_a
7 affected
any procedure
of thQ,o
n,eful
and which
¢lcmanta
can b.e jtrongl
m,*at
Soma
arv particularly
dna to the_c diffracted
pyatem
concluded
which
muffler
are
prva_t*rv
of urr/all high-purformancc
rcvicwcd.
are deacribod.
_y_tcrn,
aff_cta
large-amplitude
their
by" ga,
qualifying
aimulatc
are given
when
affect
tim
the. p_r-
circnmatancc,.
aIlcr
and
Tha
paaaagQ
dynamic
through
nonlinearity.
mufflcrn
of high-
tho uniq_:c
/caturca
of
ay_tema.
g
n
359
i
1.
Intz.ociuction
In
thi'J
paper
wt_
dytlanlicu of umnll,
the tmiqllc
a_Ipcct'J
of
the
cxhau:,t
cn|;inc,J
and
the lJpccial techniqnc_J tll_t_lhould bc u'Jcd in tcstin$1, uimulatin(,
and
at_alyzing
their
cxhatl:3t
:Jy:Hcl_:_.
_¢_LLtIII'C I:11"umall
cn/_inc:_
operating
generated
opening
of
by
frontt_d
tht_
and
tile
oflarb_c
oxhatltlt
port
O. 1 to I rnoec
tim
0xhaunt
to
it ditlcontlnutty
propagatin
5},
In _eomctrical
acoustics
ao
prOcOtltlctl
the
ph_'_ltc_l
Inhaltlvcly ohvioutl.
d,ycleped,
Application
of nonllnt:ar
|hoot
X can
nonltnaarlty"
dorrlaln
Therefore,
tile
prcat_ur_
nngint_n
(i.e.
pulueu
in of
, tim
imrformanca
and
to nhuly
in tht_
tim order
lart_ent
nmlttt_d
to
whon
tht_
oMmunt
of or
diantt:hlr),
tracn
their
noise
tim
nointl
of
probh!m
tile
tht_ory
and
harmonic
in the
and
tht_ rt:nttltrl
analysis.
(ln_o
domain_
llioro
|lt_rl bccn
diffrncttOn
for
eff0ctn
nffcctn
nonlincnr
in
el t_eomctrlcal
out
of
it
(R.t_f.
of
tile
of 8andynnrntc
effects
small
typlc_d
for
of
comprcunlv_
of
ill
tim
tile
pulses
ttl cnpt_ciltlly
tim
far
f
360
per|lone
fluid
of
high-pnrformance
trttnrtv_rnt.,
determining
(lilllellrlio_tl
acoustic
through
trim
the
if
one
i_ I{enurate(l
6).
Furtlmrmort_.
unproductive.
than
in
steepen
In ntrt_lblhtforward.
aynt0mt_
Thin
Therefore,
will
ltcotlt_ticrl
of
it in useful
Imc_ttm¢_
nl..it_c
treatntcnt
thickliCna
tntaractionn.
of
to itccotlllt
propagation
it exits
to it dincontinulty
thickncan.
trantfpnl*cnt
smaller
frona
an
it lar_Ic-
ntccp(_n
context
connid_r_Ltion
in tim
near
nonlinear
initial
geonmtrlcal
and
_tccp-
l'itllt_e
pulac
in all acoustics
conditions
it* ctu_tbcrnome
t]lc l_tzl'.Jcs
bc
mca'Jurcd
by
3/,1
inlllortant
Ill.
tim
cxtendt:d
while
will
ira
1, carrh_d
the
boundary
to
first
decomposition
of
tnchtdtn/_
7),
in
l_l'tl txlorc
thtlory
bar
occur
analyain
b_ directly
(llof.
frcqunnc_
_ 0.8
npcctrld
the
Tim
cxtcnnlwly
pulse
by
than
thai
Furthermore,
ritJctirnc
pultten
/acL
tend
commollty
of the
3 litnon
ill1 initial
mo:_t
it propa/gatcn0
0.5
only
the
port
Ihc
of pl'cntlure'J
cm.
a0
to treat tile. problem
(R.oE.
or
czlt_inc_
Z - 20
amplttudt_
ntot_p,frontt_d
natural
acout_tlct|
t'tm] i:l
thicknctJ'a
thinner
regard,
v;tlve
,l-:Jtrokc
_Jo the
with
tilter
When
mort:
and
a distance
it pultlc
hlb'h
c);hau:_t
l'atlgc
with
thi:_
llit_ctinLc!J
to /{et
A pulnt_
uxamplc_
Z-
1-.1),
tcndu
propagating
for
both
t_ in the
pulse
tltt_tlpontn_].
lifter
of
In
,t
the
amplitude,
(Rcfn.
port
amplitude
Ig
rcvi,!w
high-pcr/orIx_,in*:c inLornal-combu_Hion
:tyntcln
Is
Interested
IJy _l_._
2.
Exp_rim.Eontal
lit
"!.retire
A_tr;ttttt_
nyntt:mn
_,itil
l_l;-/{e
lll_,tltrii_,.ilnottli
flow
vt_li_cit
/hit
lll¢_llll
vtll(iclly.
lho
atillOtlllhiil_tl
th_
cy¢:io,
'_hlll't:ftii.t_,
into
_actton
_oillpll_lca
(if
{jet
of Itibn
c atalln
(if
Vi/iefitlti
[low),
(ulnl(
7 mlty
lit,.
lit
flow),
gl_/it(_/li
C/filCt_i
Ill)
axhalltlt
sty,'ltelllti
ini)tiotl,
lltiliilt;mtitlliy
tl_:
i:(_l.t,liil
/lilil;tl'(tti(lil
dl/'ft:i'ciit
tlln li_p_ll'illli_niili
iil)lilll'iltiltl
Ih¢: [iititl_iiil_:nt;ll
l)lJhll_'lulIllli)"
lilt ffllllld
|11 ILl, f, 1,
36t
of
'lhllll
lllfJ(llv
i)tJz, ti_]lltl
,
flt, W otll
_";'f)lll
()i_ Cll l_i} llfJt;
tile
m;t..:-
Lil.llt_r
ililhill./tllliiil
¢iill, ill#l
ililtl
/'llll¢liillll:iltilllr
trail _onl_ fin¢ling_ of
ill
tttlt_tt!.t¢ly
tht_i.l_ ill,l_t , Ill)
tlt¢_ e_liitti,-lt
_[tii('_lltt¢_
an are, it axp,alanlotl
vnrging
- ;tzlii)litu(Ic
firt%v
fl.Olil
(J_"
of
flllt, v iilto
it eli/l-
l" t: vt_ l'//_l 1
, the I't'.tit_ti, cii
cif fi/ilte-itti_iililildt:
llril_l,;llll
_vit.%,etl
durtnB
a portion
from
ideal
of the cycle
acoul_tic
can be an important
behavior.
For
e)camplc,
the performance
of pcrforatt_d
tubes
by the c×tntence
of inflow
tile muffler
arrival
of the
facilities,
effects
main
pulse.
it periodic
of inflow.
into
The
anda
can
from
ha_ _hown
be greatly
experiments
arc
before
wc use
source,
rcprcaented
Lhat
affected
the atmosphere
t$ingle-'Jhot
two devices
of departure
otlr work
in m6ffler'J
Ia the prctleot
uource
oource
two different
to bracket
the
I|chematically
in
l'_igurc I.
Itononanco
gan-(illed
tube
terminated
drivt_n
and its
portions
and
which
at the
pi_tonin
tllba,
Tubt_
The rcnona:_ce
in excited
end with
at the
fundamental
amplitude
in the
g_norator
to nttpply
axcttl|lg
the exhaust
wav,_form
and
Thua,
nyt_t_m.
connected
given
nninQ.
in the
Data
are
nyt_tnnt,
and
nutpattn
plotted
all
in mada
format
gear
analy_an
_llncttoflfl_
mounted
the. important
Trant_form
of the. periodic
_tc.,
of the
compressive
8 back
an 41 wavn
pt_rlotltc
wixven
for
tht3 rt_nonanceotubo
at the e_latmt
when
both
chamber
to the
for meanui'inIl
_nd for
port
sources
exhaust
intcrnal
mcannriag
are
system,
pronnur_n
in
in rcM
nhortlYaItor
with
cnnncqt:cnce
(FFT)
signal,
sampled
and
complctionofa
on tht_ crank
crank
shall
that
and'it
data
ar_
run.
mechanism
calctdatod
actultlly
in not necessary
to lltnur_
tile results
and n magnt_tlc
spectra
algorithm
radiated
detti_ acqtlinitlon
tim_
the pintos
at ncv_:ral
free-field
by a computer-controlled
art_ proc*anntld
_, 256-tooth
Fourlcr
engine,
the
w_tve travellia
mt_taured
expantJloa
system
acquired
data
in aynchronized
Fast
two-stroke
_xhau_t
_cquinttlon
q?htu has
frequency
in ttactl
bntwu_n
history
and
The
3.
Provinlt)n
locatlon_
tubs
A comparison
to a high-performance
In Fignr_
a shuck
nit, up-fronted
p/'enmlre
of a 250 cc alnglo-cylindor
renonanct_
to form
piston
to be utudled.
that at resonance
tht_ rt_sonance
largt_-amplitudn
a typical
eyntcm
_countic
(_nough
steepen
tube.
2) in a long
end by a reciprocating
the exhaust
in large
of tim wiwefol'm
forth
at one
other
tubt_ (Figure
adequate
y_ct_
art:
'_ho data
through
pickup.
by" a
Fourier
to apply
window
accur_cy
of the
results.
I
362
I
_ _:r_"¸._t::_,. :: _ :i
SIIocI_ Tube.
prctltltirt_-drivcn
bc utidic(|.
tly:ltlzrn
;lll(I
to ITiaxhnizc
au wa0 u_cd
un/_d with
tlll_ lltnl_lc-ullot
t_clintquc
ara
I(tv_n
vory
Only
|ll
i|lttl
WOrk,
for
propalintion
rcnulttt
lillc.citi
3.
lind
rclaLcd
lrttccti.
and
the
for
IICCIIrlIC
n'iufllcr-dentgn
,Pt:rforatcd
Tullcti
_ rihown
cnclonlirlia
notaliooi
The
an that
ThQ
total
of hnletl
lh¢_ liibo
tubiin
B and
arrangod
7
Of
A E ill
of AI_ for
valuoo
ara
nhown
is altto
of Lht_ cxl)erirllcllLal
he¢:l_ _tudicd
re:_ull_
ill,:third,
villihi_
lille/Lit
for
of wiive-
arc
:_ufficiclit
'l'hl_
rcpeiltilbllity
,_l't_
al'l_ catlliy
ittlch
oil
lll_l
illlin
lll_.' llrL'lilltl£C
(li/lt_llo_llic
;in_ily_iifl
Mufficr_
dt_l'incd
[O
|iron
per
l)i
litl_l
Ilnit
ilia
ldcnlifiotl
tll/i[
ill
rlllio
and
;ll'c
_ct by
AE/A
with
(llert'oz.ntionrl
rt1,.liilttl
t/l_
_llffl[l_
A in
,"it llircc_
Lhrcc
ullt_ll
1/6.
, wll_r_
ii/ciitlurell
/lytltolll,
confirm
the2
if) lliti)rl_(]il_ot
iu ;lll[}l'O_ilrlllll_ly
_roi_/iill'_tl
cxclt.d
©nclotlnrc
thl:
Lt_nh_ll
holc_
iirult
lllt!cllltgt_l_
plilticll.
D;._ II/icd
drilled
in it _l%,l_n
lly
allll
17)
Iill(|
wall
tnlc_rnal
'1'h_ygnnnrally
[]112
_tcolilllic
l"_il._llro
Ut
ttl ¢]laritctllrlgcd
ar_a,
an *_!nflnitn"
d_iCl'lllinc
Colllil_lii.llliiillll
in
Jociltiontt
Ih_ p_rfnrntlona
6,
till[
attontuitc
in a ninlll_-paltl¢_
in glllur,:
;LI)ovc
hart:
_lll_ll311l't_llll_ll_:i
Ill illl/o
Ot_clllo_cop,_ trac_t_ of
m
llit_
ar¢_ 6.35
tllla opilli
locations
internal
(l_ll_l-_lc.(]tii:lilioil
filnd_l_l_:xlhl_i
llac
tlil'illghf-throill_h
C artl
in the tlllln ltrlcl
cro_-a_ctlon_l
different
l lowevor,
In iriufflt:rtl
p_rforationa
area
extended
ILJl+ ll_._l:llil'in_;
th)t_il:l
th_
lil_l_n citrricd
the! tlc'pllltliltlc¢lr
fiBurca.
w_ve
configurtilit_tl_i
in lllgh-Pcrforri_itncl:
t|l¢l tlli_pic
A_
/'or
_lhock
l_illl_ i:l
dc_i,:l'ilJtd
e×perirllentlil
nlcihnd
have
p_rforatnd
_|lttlr_
the" inl)u_
optimization.
_pt:rlmc:nta
by,which
ol
:;;till,:
l,_lirthcr
utlpllrentlton
tli_
"l'llc
of cxan_inlnf)
HI tile
to noltlc
'fhtircforc,
to
cx]l_ltl_;l
sy_tcni
ttihc,
r_ytitt_n3rl,
the
sy_;tcil_
i:l lll_l_it:
noi.3c,
n_uffler
utility
,,.:ll.tLi:;(
1.
ptll.|_oil_
in cxhaurlt
to don'lontttrat0
of th_
tlhock
oimplc
ttlo
the
l_rr_vi_lion
lhc periodic
in ll.of.
tll_,
tllt_ ul_iforll_ily
r,_.(lilltt._cl
witil
'11 I:_ ._ llili_.',!lliioilnl
i_ _ltt_.hcd
, in wilich
is tiscd,
/_l'Ce-/il_|(I
I|;'i/,llrl!
to which
¢onfll]ul.atioil
the i_hocl< tube,
13rt2u'Jtlrctl
till]l]
ullod(
tube
In order
a 'icookii._-ctltlcr't
tntiidc
The
tlhock
to
dl/foronl
/tit:
obtnllll:d
roolll)
la
m
_1
prey|null
trace,
0tudloil
it ahow
the
of perforated
lncid¢nt
0hock
ttlbfltt
followed
(llnftl,
II niid
iiy an
_)). Th'3 uptltroarri
oxpannlon
wave
r_Ifloct_(t
7
from tim porforationn.
structure
of the
behind
Tim downstream
tranumitted
tile tranumitted
wave
wave.
The
is well
accounted
model of the nink effect of the
reduced orificedischarge
traces show (he detailed
final
steady-state
for
prcnuure
by a Mmplc
flow through the perturbation.J(withis
cocfflcicntduc to axial momentunt
but the spike and pressure
minimum
obaervcd
especially
are unpt'cdictcd
2. climonaional
effcctts
and are obviously
with
regard
evidently
to heine
cminoion.
tim nhock
the perforation
in not immediately
attenuated
area
in large.
to tin tlmorcticnl
t:dLuv AE/A
= 0. fi9 in tht_ figisro,
and D_ in tim tnilptpt_ in cvtdnat;
dlncontlnutty
rapid
the
very
lip of ( 2 - dimonnionisl)
tntt_ractp
ronultlng
npikn.
Tht_
t.
tha wvakcr
wavon_
oat
isttt:nuistion
cmphanlzon
obtisintn
_ffnctn
in our
during
data
Flfiurn
7 nummnriztan
radliste.d
notate.
Tlmugh
has
to nlow
tim rino
been
largnr
value
fist-field
¥1¢:1d about
nurvlvlng
than
that
(location
proaauro
Flgurn
the pvrforationo.
tnctdtmt
..hock
The
roflectlng
to ne_ that
0. IZ obnvrvc_d),
the t_ffoct
of finlt_
onclonuro.
of wavnn
and forth
thn odd-
,yntamn
on
dm main
effect
oxctttad
amplitude:
much
the
nmisll
nourcc]
,urroundtng
by tim pa,nage
in the tnnclo.uren
nocondary
would
llowt_vcr,
t_chatquc
unadtnthin
work
notnv,
whara nacdndary'npikon
oumbt_retl
in
va.tlyrcducing'tho
of t|m nares
heine
hack
tatlplpn
in tim ptpa to a vary
the major
affnctn
for
that important
of perforation,
at D_,
dincontlnuitT,
the
a fact
ongtnoa.
rc|nislnn
occur.
With tim experimental
pltrticnlisrly
tntlm
radiistod
pn.aibla
effect
lt_vcl (is aback
on.
muffler
parnintn
if
ntrongly
tim ntraifiht
c_nrnpl_te
of tim prc_t_anrc
for .trong_r
fact
high-parformanco
of the. comprcnnion
of the input
.pik_
down
npike
oriflccn,
larger,
more
6) than
Tim
tim ovvrall
ismplitudn,
I] .hewn
for
is nmall
F) notsn
1 mBisr
(Figure
made
nonnncarity;
bc much
up much
art_largor.
of tontine
in probably
dinappearance)
would
it nhown
the eff.ct
tim nlmck
thv numerous
nlow
propafistion
_upprcnntnn
'which
to blandynamlc
tim nplku
that
_ffvctn
the importance
8 notnn
(anti
expt_rlmentn
nonlinear
c_n occur
from
in due vntirely
by tim fact
woven
wlmr_
wow:,
wavva
in an attenuation
attcnuistion
born
expansion
diffracted
no nonlinear
t|tt_ro w_ra
which
I
When
in the jct_),
for lar_¢_ A]_/A
Important
value.
P_trticularly
lathe
of propagating
between
DI
and
analytical
ara
of the
_vldt_nt,
it in ov©n
now
polaR, at DI
are
364
I
amoother
than
tile oven-numbered,
clue to the nature
in the muffler,
with the conttequcnct_
tha far field are much wcakerl
•t,
Fisure
can
the wavvn
tntoracttn8
with
In Figur_
=orion
10.
rndtatnd
noinu
bnnn
neglected.
pnd olfoetiw
number
of tt_rmn
nrtllico
pulne
refloctionn
offact
inn
gcotnt3trical
up the ntn_llv
Incident
gradual
coraaprnanion,
thta trannmitt_d
conelud_
i'
that
Wav_ amplitnd_n
oxpannlnn
ehambar
Howovt_r_
i
Indeed,
lirat,
pulno
predict
la th_ dtf[raetlon
Figur_
1 I deplete
of
w_voform
of the dincrotn
of incident
both
that
polnt_
boa
Into a not'ion
of wt_akur
into
ntady
that
at dlnconttnuoun
365
the
p¢_r/orntod
in nyntnnaa
arrangan_nt
with
txtbt_ (cf.
I_t_f.
thnery
can not
ono-dtmtlnnlonal
th0 geometry
a mow
of both dovlcon,
of olemt_ntn
_orton
thu
An acot|t_tie
inatrvtch_dout
by the per[orated
[rontn
effects
to attcno;tt_
.combination
followed
of wav_'
nchematieally
for the
in th_ ni_ma a_ with
Would
one phonom¢_non
finite
trannmlttcd
_tftttr a eoml|_rativn
th,a optimum
norno
lmnaedintoly
tlt_rvoa
wave
ar,_ larg_
it In a very
at
_xcttatlonn,
ahowa
an th_ nc_t offact
tub¢= dtncunnndabovv.
tntcr_tctlonn
Interference.
of view
chitin'thor
for tile
of view
auporpoMtion
of harmonic
of dontruetlva
point
the overall
ncricn
correction
an tht: familiar
apoctrnm
_n vxpt_nnion
In a n_nnn,
would
the
the multiple
wttva_.
wb_r_
truncate
chamber
'JchclTaatically
the wave
thu l_UlnC point
of the
the efffoctn
in to break
during
a flvnt-ordc|'
wav¢_
in which
to 8ire
one
of infinite
too larllt_ a vnhtv
if tim npcctrum
haw= tha name
of view
expansion
number
eaua_
it in nm=n tllat
manner
within
point
acounticu
an 'dhown
to provld,a
ta calculated
The
(llnnipation
the
in the
itfflntto
8ire=
to _imply
Inany
of vlc_w ahowing
the pultJe
form
alwaya
vincoun
dlnnlpation.
I,
in
confib, ur_|tiona
when
chaest._n,
in closed
but thin
that
and forth
arc_t
Howavor,
dl_©ct
Irontn
back
and i=ll of the
can be nummtad
field,
from
reflect
uach
bctauno
"nnd raflc=cted
i
b, .Jpike_
chambt:v
known
to contttdnrcd
tile dincontinuou_
wave
cxpannion
It in well
an they
Indut_d,
ofwavc_n
trannmitted
tile 'Jinaplc
work.
chambarn
trace
ha_
9 nhown
in tile pre0vnt
ofexpttnnion
the
the corre_q_ondin
propagation
Exp__a.nnion Chambera
tented
one
that
of wave
area
of the ttetnal
ehang_n.
wave
[tenth
I).
gctlcratcd
ill
whun
the
t_o{{o/l_
theory.
a_
lhc
tinny
be
wave
seriou,31y
The
pant/ion
but
.upurinH)otJcd
chlc
to diffracted
purforated
tend
origin,
a ttitwtooth
in
_'igure
indicatint'
rttdiatcd
noitJo
incident
till
of
i_nrl failn
5.
Tha
i0_
tt[rt..tlgth
dlal_lutcr
t_Xl)ltnt*ton
chltllll_c2r
b_yond
that
uitnation,
D3
thu
itmplittido
the
tJpactrlg
of
of
Otlt
lit
Lt
ttcvcral
the
wavao
_o in filet
at*
to thf:
anlplitude
diffr*tctcd
point
fornltd
contribution
thz
incrcauet*,
their
D3 havo
tJlt_ oa_t_
larsc
tliffra.ctctl
from
of
pcalct_
tl/twtooth
lit location
hitvo
t
in
linear
At
of
WitVt]_
nint_lc
incrcaut_tl
the
noittt_
plt|'ticuhtr
arctt
l'gtiO
value..
Concluttlonn
It hiu*
fronted
bt:t:n
thrown
lttrRt_-nmplitudt:
porformanco
that
home
prett_urc
unique
puhtort
featnron
in
tho
of
t:_hnuat
the
for
which
ttirnul_ttett
(wt:ak
tH_ocktt)
uucful
to
Ihu
tt:nti.g
tho
anti
actual
qualtf!tin
puluo,
tn deucrlbod.
dcuiflnnr
t_xarnplt:n
]l_tw_
r, ccount_d
for
ilrtportant
w|l¢'n
bo_n
for
/{Iv_l_
Tho
|ntluo_
An
(littcontinuoutt
tcchniqu<:
di;_gnot_lict_
and
hall
an_lyt_
ltx.t_ t_tt:ap-frontcd.
366
axporimnntal
advanilyclo
lxlodific_tion.
phcnoll_clllt
but
which
of high-
t_Imulatlon in
prctttturo
tho
dotsign
o[ two-dinar:hi*tonsil
in on_-dit/lt:nninl_nl
the
$ nlttfflot',l.
with
nt¢cp-
nyttttma
intcrttal.cnrl'tbuatloncn/_int:a rt:quiro accuratu
procoduro_
m
r_t
1'_ its ohvioua.
col;titre
the
while
Tht:ir
ex-
fhtchttttiontJ
aprcading
;ltld
Ihe
behavior
u[ it flon|illc_tr
w_tv_
than
cxpan/lion
ill
fruqnc'ncy
value,
free-
ansmitted
to the
geometrical
rJhock'd
chanll_er
to tnc,ocatt_
high
and
frotit
aU,gravatctJ
t*aturation.
i_ more
by [ho
conaid_rationa.
different
LI
cot_trary
diffl'acted
contltinin_
waverJ
t_x];itnttioll
itttt:nuation
the
at 10cation
tthock.
nit tile
13
nonli/tcar
tilt: diffracted
very
it conutant
by
two
lind
t_onlint_,arity
at
pt:r_i_t
emitted
interior
incident
tilt-' wavulunl-lh
uimply
witvtlforna
DI,
of
arc
clads
to ttatu;'atc
"murgt:"
with
the
reflected
thi_
noittu
of
and,
by one-dimdntlion_tl
frontu
the
exanH)leu
wavc_
In
itllet
by otle-Hi:l'Lcn'Jional
of
the
extended
procc:_tJ
t_f tube,
two
ill
on thcuc
to
lhu
an
of diffracted
ill cxperiml:nttJ
evident
wavc_.
tendo
wltvett
of
rcfleclion.J
_ttl ill wt_]l kno_.:.llt
wltvctrain
at
_]low
oi)._lc l'Ved
itl*C
el_d of
multitud.2
.Jcctiotl:;
tubcutgaudynamic
bt2cltn'Jo,
of
the
13
miiltiplc
cliambcr
the
undere:_iil_l;ttcd
12 and
forin'J
chaml_cru.
from
rcpre:itm[atiotl
thai
in :Jtraight
Irigurcz
field
lhc
t_×Lcnt
propa_latC
uytJtetTt
diffract'J
:ll;cLch_
To
they
:t wave
ttro
tt:chnlque
riunu.
that
it* al:o
Two
|;hat
nrt:
particult_rly
.or
Rcfcr0ncos
I.
J. J_. C1'ctlg. H_VC_t]_
,_I1ockrJ
in Opezl-L'_ndcdDuct:J witl_CompIe:_
Geometry",
Ph.D.
Thesis,
California
Institule
of Tcchrlolog),.
Pasadcnn,
CA. (1977),
Figure
7.
2.
G.P.
ghtir and J.A. Spcchko, "Sound Pressure Levelu Gcncralcd
by Internal Combustiot_ Engine J'_×haulJt 5y:d.emtJ r', SAE Tr;tn'a._.._I
0
563 (1973},
Flgurc 4.
3.
W,A.
IIuol,_o.
" In ve'atlg_,tion
"
and lh_ning of file Exhaust
of Small 'I'wo-Stroke
Gyclc l_nginclJ",
SAI_ Tri_nu.
77,
(196fl)0 IVtgur_a 17.
_i.
M. /anibor,
"Tha Exhauut
Syntem
of tile Two-Stroke
Cycle
]_ngtno",
SAZ Trans.
77,
18d6 (1968),
Figurea
Z2, Z,I.
5.
.I.D.
Kollor,
"GOom_tricM
Acoua[icn.
Shock W'avua", Jour. App, l)hys.
25,
6.
.P.G.
Frlcdlnndor,
(1958).
7.
G.D. Whithamp
Lino_r and /_o_linear
Son_ (197,1),Ch.' _.
8.
3. H.'P. Wu and P. 1a. Ontrowakl, "Shock Attcnuatlon in,t
Duct",
in Shock Tuba R_n,mrch
(cd. J.L.
Stolh:ry,
A.G.
and P.R. Owen}. Chapnll_|l and lli_ll. Lvndo_l (1971).
9.
SotLnd P_lnc0,
I. Tile Theory
93g (195,I).
Can_brldgc
A.P.
$_urnowaki,
"Motion of a Shock
Duct*', Prace Hauk.
/vioch.,
Politcch.
System
563
of Weak
Univor_it¥
Pz'caa
_Yavc_, John Wiley and
Pcrforatud
Gitydon
W_vc Along a Pcrforah:d
Wartl;_awaki h Nr. l_.._l(1972).
n
367
.
4
A
¢,
MUFFLER
•,,_--T EST SECTION
_-
GALCIT
SHOCK TU BE
RESONANCE
TUBE
DIAPHRAGM-"
FIGURE I
THE GEOMETRY OF EXPERIMENTAL
FACILITIES
36B
4-
670 cm
50 cm
_'--J-
Ground Plane
I
_
( Location
210cm
Resonance Tube
76ram
H R 2100
_
rtADC Conlroller
I' Beta
•_1Pha,,eLockedLoopJ
Clock
!
A-D
Converter
I
Magnetic
Tape
CPU
J.A. Prestwick
_:
80mm-Bore_
,OOmm-Stroke
_
_,
r-Magnetic
"
i'
Pickup
_D._SMHo
tP.or/
FIGURE
2
Paper
J
Tape
Plotter
Disc
I
Teletype
F)
o
front
front
(i|rbitrary scale)
Vertical
llo_'izontal
0
17_
.5;_ O,
(-,9.E
106
197
scale
138 m__B
cln
scale
I m_.S_
167
(D ;tat:a&i#4_ - ;l,'n)
FIGURE _ COMPARISON OF RESONANCE TUBE, A, AND MOTORCYCLE
ENGINE,8, PRESSURE WAVE FORMS
(Location
Dia hragm
Wall
Driver
Section
_[
Origin
_.
•
Main
Cookie
Section
Cutter
"
FIGURE 4
l
GALCIT SI,_ INCH SHOCK TUBE
i11
t,
_
_p
-,:= ;,
L
:
-....
Test
i ecti°n
F
=,.oz.1
Resonance Tube
I
.
{
Shock Tube
s-Enclosuro
I
A,B, Or C
Transducer
V,
Locations--
UI
U
--..._._
DI
D2
All Dimensions
FIGURE
=m
I
.........
E×_T
5 PERFORATION SYSTEMS
Cm,
. ....
_......:.,..:,.
::3
oJ
,!3
A_/A
0.44
0.89
1.78
£)
THE EFFECT OF PERFORATED AREA RATIO
ON REFLECTED AND TRANSMI TIED WAVES.
(MACH NO. .---1.15).
FIGURE 6
im
0
c_
t_
Location U
,
_0
12.0
Location
,
FIGURE
t
Tins
(_
7
_
F
Ul
Location DI
...
_0
_
I
!
00'
Tins
I0.0
",',
J
Tins
Location
.
I
12.0
D2
I
Tins
PRESSURE HISTORIES OF SHOCK PROPAGATION
TUBE AE/A_ 4.00_SHOCK
TUBE
I
12.0
PAST A PERFORATED
Enclosure A
,
B
C
I
I___..
o
_
O
o
FIGURE
p
•
•
AE/A = I,TB
Scales:Top And Middle Rows,IOOmBar-I mSec
Bottom Row, IOFBor-I m Sac
B PRESSURE HISTORIES OF SHOCK PROPAGATIONPAST PERFORATED TUBES,
RESONANCE TUBE
....
F
In
,
,=
.
=---
Resonance Tube
/_Removoble
_.° _._
-J -I
i
Extensions
/ "-,,,
_°_
1/ ..,
_ I--,-----74.6
_ 4.-
\
30.5 4
_.,
I
.
4.a "6o.o
Shock Tube
15.2
Ul
=
U
1 )_ 5/k'l
-3['-"
Dimensions In Cm.
DI
D_
_°°°"°°" " )).,, -'_ '
Chomber
A
B
C
FIGURE 9 EXPANSION
CHAMBER SYSTEMS
D2
6.35
8,25
A2/AI
2.77
,_.69
I1,4
9.00
t
E
I
1
I
---Tol2
.-lk-_-
_t_1-1"o. ITi2
......I
I
I
I
.*L
.:..,
FIGURE
IO EXTENDED
D
n
n
377
INLET
SYSTEM
FIG. II. SHOCK INTERACTION WITH AN EXTENDED INLET
E
l,
n
C_
"0
,_
Location
_<
I
?ms
_"
I
UI
.... J
01Location.DI
_
I
T ms
12.0
I
J'
_NO
m LocationD3
n
'O
Tins
0"---"--" ......
J......
12.0
J
LocationF
,
IO.O
_
ol
O
,
I
L
Ti
......I
.
Tins
FIGURE 12 PRESSURE HISTORIES OF' SHOCK PROPAGATION THROUGH EXPANSION
CHAMBER,B,
MS _- 1.17, SHOCK TUBE
.I
12.O
0
__- _
o
o JYLocaonu
o
o
m
E
o.
m
E
O.
.ocotion DI
_o _
'0
o
,
, d
T ms
_.
Location F
12.0 _ 0
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JOItN
31
October
JAMES
W.
DEERE
1977
ItORICON
,#
WORKS
,
r_
MOORE
MEASUREMENT
NOISE
IN
OF ENGINE
DYNAMOMETER
EXIIAUS'I'
[_OOMS
A method
of mesI*uring
engine
e×haust
noise
h_is been
developed
as a substitute
for the more
complicated
snechoic
room or field
tests.
It is simple
and easy
to use and
does
not require
expensive
test
facilities
and equlpmctlt
or modifications
to
the o_haust
system.
Tile sound
readings
and insertion
loss
can
be determinnd
ulmultancously
with
dynamometer
power
measurements.
Tile results
hans shown
good
repeatability'and
/*re not subject
to
the variations
in weather
conditions
encountered
during
field
tests.
Ths
test procedure
was developed
b Z Richard
Kostecki
of
ACS F,ngineuring
in Toronto,
Canada
and has been
used |lateensfully
by ACS
for exhaust
system
d_velopment
for several
years,
A similar
test
IIlethod is also
used
by two other
snowmobile
m_nufacturers.
John
Doers
has used
it eatcPs:v_ly
in tile
dev_lopment,
compari:|on,
lind selection
of snow_cbile
tlnd small
four
cycle
engine
oxI_aust
system:*.
Flgur_
I is a schematic
diagral,
of the test
system.
Th(_ oK||aunt
gas dlscharg_s
from
tile muffler
(I) into
a 4-foot
long,
2-illc|l
diameter,
flexible
exhaust
pipe
(2) which
is anchored
at tile loose
end
to a 60-pound
_t_el
block(5).
The exhaust
gasses
can be
evacuated
from
the test
cell
by the collector
(6).
The sound
pressure
i, measured
through
tl hole
in the end of the
pipe
by a
microphone
(3) in a special
water-cooled
mounting
(4).
The length
and diameter
of th_ flexible
pipe
wcro
n_lected
after
_xt_nsive
e_porlmentntion
and are designed
to isolat_
the
mlorophons
from
the engine
vlbratl'oa
and
noise,
sod
tg provide
adaptability
to various
exhaust
system
geometries.
Engine
performnnce
and exhanst
noise
gunuratlon
are not affected
by th_
m@auurement
[system.
The sound
level
is rz_,ad on a sound
meter
(7).
Octave
band
measurements
ct_n also
bs tske_
_8).
Correction
factors
arc
applled
to each
octave
band
to compensate
for nonlinesritles
in the messuremellt
system
nnd
for comparisonn
to field
_osts.
Thls
correctiou
_rocess
is simpliflod
by it spcctrtlm
equalizer
_93
'
(9].
JOHN
PAGI" 2
A HL'TIIOD
OF
ENGINI_
Th0 upper
CLl_Ve
of a _llowmobilc
DEERE
I_XI[AUST
HORICON
NOISH
ie
l,_igllre
2 shows
mul filer
nle_Lstu'ed
WORKS
MI';ASUId';HICNT
;l
ou
L_,pJc_ll
Lhe
test
IN
OYNAblOHETEII
e×hau'at
fixture,
ROOMS
llOt'Je
spectrum
A correction
factor
is
subtracted
frorlt
eacIl
of
th0
seven
octavu
readings
to
extrapolate
to
the
oxhsust
nois_
spuctr|lm
in
the
lower
cu-_'ve
_l_t
would
result
from
¢_ snowmobile
drlveby
sound
test
at 50 feet.
The sum of the correctt!d
octave
bands
produces
the overall
A-welghted
level.
Figure
3 shows
the spectrum
subtracted
frollh each
octave
of
of
correction
factors
that are
e×haust
eolse
measured
on th_
test fixture.
The uppur
curve
is the diffecenci_"
between
exllauu_
noise
Ineusurements
made
in |Hi anechoic
ehumbur
and wlth
the tout
fixture.
It co_'rects
the noise
measured
with
the fixture
to an
A-wuigllted,
"free
fluld"
sound
level
at a dl,Jtanee
of I foot.
(Narrow
band measurements
have shown
that
the frequuncy
llnearlty
of the [11en.JureirLunt syUtelll is excellent
withill
each
octave
bund.
A correction
ill tJlu wldur
octave
bands
is _lll that
_s necessary
to compensute
for tile noellnear
effect
of the ,l-foot long
flexlblc
pipe.)
The middle
curve
converts
the 1-foot
!ii,_.esurcll!entto 50 feet.
Tile total
correction
is shows
ill the lower
curve.
Figure
4 demonstratus
how
the 50-foot
correction
fneto_" was
developed°
Oct,:re
bands
of whil:e,
random
noise
produced
by /In
_coutJtie
drlv(:r were
muZl:_urud over
a gra:_s test
site
at a dlstsneu
of 50 feet.
The mJcrophoee
w;Jl; located
4 feu_
from
the ground
surface,
and tile fiotlnd flout'co w_iu placed
at
I/_J, 1/2,
1 and 2 feet
above
tile ground.
(The test
site confirmed
to the requlrement|i
of
"SA_ J192
, Sound
Level
Me_isurum¢;nt
Procedure
for Snow Vehleles".)
Tile variations
in nouiid level
with
sourer
heiqh_
are c_|llsed by
grotlnd reflectlonu
(lieu SAR I'ublicatioe
740211,
"I;ffect of Ground
On Netlr llorizontal
Sound
Propagation"
by Pie:cy
and I;mbleton).
The i/2-foot
level,
which
it] about
the |;eight
of a snowmobile
exl|ntlSt, provlduu
the 50-foot
correction
i_c_orfl
uhown
ill Flgur_
3.
T_sl:fl
h_%ve ||flown that
chlu exhaust
no|no
,leauuring
system
gives
sound
levels
within
2 dl} of lllt!;nulreltlCl]tU
made
in _ln anechoic
Chamber.
Correlation
with
the e_|l_lust zlolue predicted
in ChOWmobile
pastlby
teutu
It_ dlso
excellent.
'l'llusouIld level
difference
butw_un
elm|let
cxh_uut
syutt_nsl on the :]a,_e exzgl._e or In the
name
vehicle
can be compared
witillll I dIl.
']'he cDuvcnlence,
repuatab[llty,
.led nlmplielty
of
th's _*(:tl]od of uxllalust nein_: I:lea:_ur_.,ent make&,
it wry
u.,_ful
in small
')_glJle muffler
development,
selcctlo_
a._d
feting.
Nol:)c
_th,}r
I
flle_l_nlr_:fll_ts|lav,. _lot been
attempted
on exll_ust
systelltS
£h_xo those
on UllV.]_, two cych_
_lnd felt/" cycle
englnus.
99B
SCHEMATIC
DIAGnAM
/
/
/
J/
/
/
Acou_llclM_ch_ntc_l)Componcnt_ 1
/
/
1
Eloctr0nlc Comp0nenls
FIGURE 1
F_XHAU_TBOUNO L£VEL
(i_NfM
a
dlt
2
.... "
,
II_
_
110
110
.........
dBA
6
-CORflECTEO
(50' D_'(IVg
_TI
/P"_
DMID C_'NTEI1
3g_
/
o,..,..
1
OCTAVE
i
LIN
FR£QU_NCY-
_1C,I JFI|_
2
IIX
-10
(FO_o1' di_tnnce)
to_t tlxluro
*
o/Q
"_0
SOUND
e ,=----4 *'_
LEVEL
COf_RECT'ON
FACTORS
dB
x _'_
-,o
For 0round
o,,oc,
(1' to 50' di_tollco)
_
x%.,%_
x'_'_x
/
-B0
OCTAVE
IBAND
CENTER
FREQUENC¥_Nz
FIGURE 3
-0
_tD
GROUND
ToFROMD,_O,D'I'"
dB
flULE
',%,
/_
w.
/
"v
--I_
t
(
-;o
BOURCE
MEIGtII._T.
_o
)_1 OCTAVE
*_
I_AND
CENTER
FR£QUENCY
4_'o-FIGURE 4
:
.i
!'i
t|_
1=_ i'_Q _oo _ooQ=¢,oo4oooiooo).oo
TIlE APPLICATIOfl OF TIlE FINITE EEENEtlT _dETIIOD
'I0 SIUDYING TIlE PERFORI_IAIICE
OF REACTIVE &
hy
k.
Craggs
Dept, of iYlechanlcal Engineering
Unlverslty of Alberta, Edmonton
Alberta, Canada.
IBTRODUCTIOIi:
Tills
paper
gives
n brief
review
of SOlllO of
_York carried
tile authm" on the appllcaLinn of acoustic finite elements
flerperformance.
out by
to _b_dylng muf-
It is shown that tilemethod can glve plausible results
for a models having a S|Illple
geoln_tryhot,use the resolts conlpareVery [dvourabTywith those obtained by other methods, l]ecausethe elenlentsused in the
w0rk have a variable shape
riley can be used to slmuhlte systems wlllch ITllght
have a dIFFlcnlt geometry and still give
nleanlngfulInformation. Thls Is
one of the prime vh'tees of the nlethnd.
In Ironrecent papers (1) and (2) it was silow,tllatfor transilllSslon loss calculations th|.
_muffler has to be Lreated as one which /losdamplageven when Ule muffler is a reactive one.
Thls Is because reactive muf-
flers lose energy throogh radiation at the Inlet And exhaust parts. As
sucllthe eqaatlons which govern tilemotion OF tilesystem are expressed In
termso4 cor,
plox quantities. Tilegeneral Form of tileequations Are tile same
for both t[lA[lsmlsslon
loss al_d IoserLIon loss colculat'ions.
As tiletheory Is available elsewhere (l) and (2) it is kept to a
mlolmom in thls presentation, llowever,tileconcept of an absorption ele'ment
has riotbeen used before and It Is introduced ilere. These elements are particnlarly nset'alwhen deallng wlth absorptive boumi_ries havl[19An extended
reactlen. A l)rlefApplication of these elem(:ntsis discussed at the end of
the paper.
2.0
" '
CENERALTIIEORY
Tileappllcatlon of the finite element method results in ¢Isetof
linear equatlons, Boca.so all of
the sft_latlonsare essentially for damped
systems the problem ilnsto be formulated In terms o4 complex qnantItles,
llowqver,using the method given In reference (}), the real and imaginary
N
401
'u_r,._':_p_C._:,.;_e
d ....
._..: ;_.,:_.:;.,
_, _ .
,_,_,,.:',.,_/,:_
,.........,
, .', ,_'.,
..,,
2,
parts
can be separated
and the syste_(mequations
can be expressed
entirely
in
terms of real quantities,V/henthisis done, the equationfor reactiveand
dissipative mufflers all have the general lena shown below:
Here PR Is the real part of the acousticpressure;PI is the imaginarypart;
QR___Isthe real so_reevector;QI the Imaginarysourcevector;[A] and [g]
are the kineticenergyand strainenergymatricesrespectively.Thematrix
[C] is a dissipationmatrix_hlch onlyhas non-zeroelementsat pointscol
rospondlng to the boundary nodes _here the energy is lost either through
abso'rptlon
as with muffl_shavinga dissipativeliningo_throughradlatlon
at the Inputantloutput partsas In a reactivennJfFler.In tilegeneral
probleIn
thematrix [C] has the realan(limaginarycomponents[CR]and [CI],
Thus If we have a given soundsource (Q) thenthe acousticpros,sure at any point wltiHntilesystemmay be found tiu'ough matri_inversion,
using standardcomputersubroutines.
2.1 TRANSMISSIONLOSS CALCULAIIOfIS:
The transmission
loss refersto the performanceof a muffler
vlhenit Is insertedinto an infinitetransmission
flue, .SeePlgoreI,
The sourceis doe to an incidentprogressive
wave, of magnltud_p_, wHch
strikestheentranceof tile
muFFler. The responsethencontainsthe reflected wave,P- and the transmittedwave PT, and pressuresat numerouspolots
inside, The transmissionlass Is calculatedfronlthe formula,(._ee
references
(1) and (?) :
T.L-
20 log [I?T"
I
Becauseof the infinitellne thereare no reflected'waves
eitherat the input
of tileoutputstations,and the impedanceat thesestationsIs accordingly
entirelyreal;being equal to pc,where p is tile
rm_ssdensityof air and c
is the speedof sound.
_i
Transmlssloolosscalculations
are usuallythe first step carried
sltuatlon_fhlchis applledsome ca_itlon
is needed_ileninterpretingthe
402becauseof thehighly idealised
out In the deslgnof a muffler, llowevar,
3.
the
i
results
for _ practical
on tile Input an:l outp.t
Ill,OPtion
Loss
•
22
siLuatlon
lhles.
i_hero reflected
I_luch ,]ore
A
i_dves are
I_leanlngful
present
calculattml
both
is
for
Lime
INSERTION LOSS CALCULATIONS
Tile Insertion
|eve}s
_lt a pl}tot
_then,
two sets
los5 refm's
beforn
to the difference
and after
of calculations
the i,sertlorl
are
required;
ill the sound
of
the nluffler.
lnteoslty
In gt:oera].
one for" calcukltlng
tile respollSe
In tileorlghlal sitoatlon and another for tlmesituation including the muffler.
Tile results
_Ill
tion
Iiilpndance.
wi]l
clearly
depend
upon the
Tllere
nature
depend upoo tile Hldlvldual
slluwo In Figure I; Olle case Figure
source with tile I_luffler
tenllinated
otherD
half
Figure
3.0
1 {c),
space through
trnnsn,lssloo
loss
In a later
or the
source
is not a ualqee value for
ca_e.
an laflnlte
loss
Tvlo dlffereoL
radia-
aocl l.be result
_,odels are
l (b) hilvirl9 a coostant veloclLy
in an Infinite
traoslilisslon
line
having a simmer
source,
baffle.
and Io_ertlon
and tile output
Insortlo/l
but being
Tile finite
loss problel,s
plstoo
and tile
terminated
elenlcnt
results
sbo_in Ill figure
hlto
a
for
tile
I ,ire discussed
section.
TItE ACOUSTIC FINITE EL£NENTNOBEL
1'he aCOllStIC finite
paper
I_ ._ho_n In fl(lnre
allows
for
the _lement
._hape,
a linear
It
variation
Is ,_n l_aparamelric
Therefore
geo,_tr.y
e]elllent
2,
of pressure
e]e,rent
tile ll.'io of this
to he treated.
used to oI)taIIl
Is a hex,lhedral
the l'esalLs
ele,lent
thi_i
bef._een the node points,
Ii: can lie dl_torted
element enables
For the results
for
havlog _ nodes and
l_ecause
ta ,_n¥ r_asonal)le
probler, s havlog a dlfflc,lt
given here
only
a×i-s.v,lnetrlc
case_
l_ere studied,
k/lib axI-synii_etr¥,
the three dimensional
problem can be
trollied
as a t_o dlmensional one _Ith a Substantial
reduztlon
in tile slze
the problem,
lle_ehe(Iran
In thls case Uie r.'ductlonIo size _as achleved by forming the
into
a segment of a trick cylinder,
llavlng equal r_dll
tively
A typlcal
m
and length cof_rdln,ltes.
4 nodes instead
Io figure
many other
3.
of
.qrld
Although
finite
of 13, (see reference
,sod for
this
element
a simple
IS quitn
solutions
crllde
tlleo oqm_tlng
Th(: elc_lent
tile pressores
thus used has effec-
l).
exl)aoslon
chamber ,l_de]
colllpal'ed _Ith
tile res,lts
:)03
ohtahled
is shown
those reqnired
_ero quite
h¥
accurate.
4,
4.0
RESULTS
l.bstof the results given below are to valldate timemethod.
Many
of these can be obtalned From shilpleImlOdels
of tlmesystem and they form a
useful
check on time procedure.
lli(Ifflers
Ivben it
Is s trtctly
solution
place-wave
breaks
This
Carl be _sstllmledthat
is particularly
true
aCOtlStIcs wl thin
arid thns one dimensional.
dolin when tile wavelength
Ilnwever,
approaches
For reactive
the expans loll Challlber
the plane
wave
the chamber diameter.
It is then that tilefinite element rl_delsho_s a distinct advantage.
Results are discussed in hlrn for reactive mufflers, dissipative
P)llFflers
with a locally reacting boundary and flnaIly for lined mufflers with
extended reaction at the boundaries. The extended reaction is e_delled by
extending the finite element approach to an absorptive material and then formleg-an acnustlc-_bsorptlon
4.1
REACTIVE
n_del.
MUFFLERS: TRANSMISSIOrI LOSS
The transmissionloss of a simple expansion chamber In terms of
the area expansion r_ff.lo,
m, length 1 and w(_vemnnber k is given by a formula
due to DAVIS (3)
:
I'.L. = lO lOg)O (l + ]/4(m- I/m)2 sln2 k])
Th_ finite element res.lts are co)nparedwith those obtained form this fo_Jula In flgnre 4.
lhere is excellent agreement. Further results correspond-
Ing to higher frequencies are given in reference (1), they show that when
dlamezroln_(h,sare excited they can either act as passlng filters and
thus
reduce the trnnsrnlsslonloss or as blocking modes.
figure
(5)
sho_ the effects
of extended
inlet
and outlet
pipes wltIllntimechamber, lhese act as (inarter-wavel{:ngth
filters whlch Rive
high transnllsslon-loss
vah4es whenever tile
length
of
tlte extended
pipe,
le,
Is given hy Kle • nn/4, when n is any odd integer. The Finite elemerJtresnlts
show this to he tilecase.
- ".
4,1 INSERTION LOSS
Figure (6) cnrep_resthe transm_isslonloss resells _Itb the insertion
losses calculated for the t_o sltuatlnns shown in figure I. There Is an
a se_t-lnflnltespace tileinsertion loss shows negntlve valnes, thus tilemnfone.us
difference
and
In one
case,
_here the muffler
Is terminated
into
fl_r is enhnnclnR
the
soun(I,
where
transmission
loss calcnlatlons
would
Indl-
I
t,
o4
C
5,
cote a snbstantlal reduction.
4.2
DISSIPATIVE NUFFLERS : LOCALLY REACTING DOUtIDARIES
Tilecalculation of tlletransmission loss for an expansion charllber
having a cyIIndrlcal absorptive Ilmlng Is not a simp1e matter, although design
procedoresdo exlst.
See l]eramek(4). It can be handled wlth a finite
elenlemtmodel by so]vlng the gemeraI equations given In equation 1.
l_henan
absorptive llmlmg exists tileternloIn tell and [CR] are non-zero at points
corresponding to tileboundary nodes _d}erethe liner is attached, The terms
in [CI] and ['CR]depend upom tileform of the liner hnpedance. In thls model,
tileliner _Yasassonledto b_ local'_yreacting _PIthtlleImpedances given by tile
emplrlcal equations developed by Delony and Dazley (5).
See also reference (2),
These equatlons allowed for a seml-rigld porous materlal In whlch tllecharacteristic Impedancewas a function of the matei'lalsresistivity. Tbe impedance for any thickness was then caIculated by assnmln9 that the oilierend or"
the layer was attached to a rigid layer,
Results for the transnllsslonloss ore shown in figure 6, these
show tilechanges which occur when tilethickness of the ]iner Is Increased,
Nfth a thlnliner, there I'sllttle change from tileunllned reactlve case,
As the thickness Increases, the multlple hump transmission loss characterIstJc of tliereactlve muffler is replaced by a slnole hump _hich has a mnxImumwhen the th|ckness of the liner Is 'approximatelyequal' to a quartur
wavelength, Thus the n)axlmnmvalue occurs aC lower frequencies as tilethickmess Is increased.
floweret,there comes a point witchthe thickness Is too great and
the magnftudeof the reflected wave fr_n the hard hoandary Is small, in
which case the boondary Impedance of tileliner approaches tilecharacteristlc
Impedance of the liner material and no further changes in the transmission
]0"5
occur,
DISSIPATIVEMUFFLERS WITIIEXTENDED REACT]OIl
An Improved model of the aceustlc llnlng Is obtained If the
assumption that the hoLJndaryIs locally reacting Is removed,
In order to
achieve thlsan acoustic absorption element has been developed based on a
m
Raylelgh n_del for a rlg|d-porou_ material, Tillselement is again ilexahedral
4O5
i
/
•
ii_
_
|n form and Is entlrely compmtlblo wltllthe previously n_ntloned acoustlc"
i
element,
The general
ed by an equation
being
forlll of tile
simtlar
to (1),
found in the matrix[el.
now fully
populated
response within
the medium is again
the differences
with
For the absorption
and tile magnitude
of
tile acoustic
equations
this
the terms are proportional
govern-
equation
matrix
is
to the
resistivity of the material. Further, details of thls ele;imntare to be
published in reference (6).
lhe absorption
eIerllentscan be Joined to acoustic
ing the pressures at the CniTW]}on
node points.
elements by equat-
A typical axl-sya,netricmodel
is shown In Figure 7; this represents a cylindrical expans|on chamber wltb
a thick lining. Results for such a cbamber are also shown,
tlvlty R
ilhen the resls-
- O, the model is then of a simple reactive chamber and the trans-
mission loss has the typical "squared sine Have" appearance.
The lining great-
ly increases the transmisslnnloss _hen the resistivity R
10,000 Rayls/
-
metre . Although experiments need to be cdrrind out to verlfy the results,
the general form of the curve is in agreement wlth those obtained from lined
duct silencers used In ventilatln9 syStEmS.
CO_IENTS.
The use of acou_tlc'finlteelements for modelling SilEncEr systems
has been descrIbed. The _thod at this stage is particularly valnable when
dlfflcult geometries are to be simulated and for predicting the performance
at IHgh frequencies when the WavElength approaches the dlan_ter of the expansion chamber and one dimensional tileorlesno longer apply.
It is also use-
ful for modelllng dissipative liners either wlth, locally reacting model In
whlcb there Is no substantlal increase in the size of the n_trlces compared
wlth the reactive case or _Hth absorptlon elements. The method can easily
bE applied to Transmlsslon_.ass or Insertion Loss calc{_latlons.
The contents of this paper are malnly concerned _Ith tilework of
tileAuthor. floweret,the method has been applied to m_|fflersby other authors
_ith some success.
Ynnng and Crocker (8) calculated tile transnHsslon loss
of an expansion chamber using rectangular elements.
cansldered reactive mufflers using ax|-s_etrlc
_gawa
and Ornate (9)
ring elements and later
Kaga_a, Ynmab_chl and _orl (10) considered tiletransmission loss of a mofrler
wltila so_nd absorbing wall.
/tO6
REFI_REPEES
(l) A, Craggs 197(3"A Finite element r}letbod
for damped ocoustlc systems;
an appllcatloo to evaluate tlleperform,oNceof reactive
zIlufflers."
Journal of Sound & Vibration (4_) {3) p. 3/7-392
(2) A. Craggs A 1971 "A Finite e]ement method for mode]flog dlssIpatlve
mufflers with a locally reactive IInlng." Journal of
Sound & Vibration 54 (2) p. 285-29B
(3)
D.D. Davis Jr. }g/5 In liandbookof i_olsoControl, C.M. Harrls (editor)
rle_York : Nc(irol_-HI]I
Book Company Inc. Acoustlca] Fi]ters
and Mufflers. Chapter 21.
(4)
L, (]eranek1971 Noise and Vibration Control _e_ York, F}cGra_Y-Hlll
Book Co.
(5)
M.£. DeIany aridE.R. l_azley197D App11ed Acoustics 3 105-116.. Acoustic
properites of fibrousabsorbent materials.
(6) A. Craggs A F1nlte £1ement Mod(:lfor Rl_/idPorous Absorbing NaterlaIs
to be published.
{7)
C.I.J. Youn¢jand M.J. Crocker 1975. Jmlrnnl of the Acoustical Society
of America 57 p 144-148. Prediction of tileTrarlsmlss|on Loss In Mufflers using the flnlte element n_ethod
(fl) Y. KagaHa and T. Omote 1976. "Finite £1emenb SlmLllatlonof Acoustic
Fllters of Arbitrary Profile _Ith Clrculnr Cross Section."
Journal of Acoustic Society Am. {30 (5) p. I003-1013
(9)
Y. Kaqawa, T. Yanmbuch! arldA. _r1. 19/ "F1nlte ElcalentSimulntlon of
A_i-Syn_etrlc Acoustic Transmission System with a Soun(I
Absorbing fin11.Journal of Sound & Vlbratlor|
H
.I
407
Figure Captions
Figurel Modelsfor TransmlsslonLoss and InsertionLoss calculatlons.
{a) Transmission
Loss (b) InsertlonLoss : ConstantVeloclty
sourceterminatedIn an Infiniteflee (c) InsertionLoss Constant
velocitysourceterminatedInfinitebaffle.
Figure2 The elght node Isoparametrlchexahedralelenlent.
flgore3 Two-dhnension
grfflfor an axl-s!nnmetric
expansionchambermodel.
Figure4 TransmissionLoss. bolnparison
of finiteelement resultswith
exact one dimensionalsolutlonat differentexpansionratiosm.
Figure5 FiniteElementresultsfor the effectof extende(I
inlet and outlet pipes.
Figure 6
Comparison of Trans_nlsslon Loss with Insertion Loss.
element resu]ts. See Figure 1.
F1nlte
Figure7 TransmissionLoss for Expansionchmnberwlth a cylindrical
al]serbent lining. Impedance calculated using De]any & gaz]ey
equations. Figureshortseffectof lining thlckness.(In.a)
Figure8 l_I Transmlsslon-Loss
The,,l-sx_metr,c_Ith
Ace,,stfc-Absorbent
attd_Ithoutany
f,nltee,ementgrld.
absorption.
408
i- j+. •
•
:. F
l.
'
.+, +... - , ........
,,
,+
p÷e J(c+t-kz)
I
--_
I
....
+-'+.,It
f-++"
U_ Jmt
I.
,A_"
-
i,
__
•
{c)
'+
+(mt+kz)
[NPIPI]T_ II/_FFLE
____
/
E
"
"'x
FJgurm I
'
//_/+,+ *,-,.
t,o?
-=mm_,__¥++
'
/
,
+ --
i, ==
\
....
1
Fl_ure 3
f
411
r
.i
.I
++
., +t
I
d
D
I
_blml
I!
1
!.
I
t
.-
I!
.i.. ¸¸
I
' I
P
_.,.--.I
J
I
0
'
I
'_
i
l
i
f'_
I
oIS..4
• .J_ 2"
•
_IL, ,
_T.-_,_,.
• : &
.'L_
A COMPARISON
TESTING
0P S_'ATIC VS.
pRoCEDU_£S
FOR
MUFFLER
DYNAMIC
EVALUATION
I
b
i
:,
W. L, Roncl
I0/21/77
INTRODUCTION
:
FOr tile
past ten years, Original
Equlpment
_xhaust systems |lave been
designed
to meet tile requirements
of SAE Test Procedure
J986a.
J986a
was the first noise test standard for light vehicles
in this country.
The original
development
work oa the procedure was dose in early 1966.
The standard was first _*pplied to new vehicles ix] 1967 and was
revised
to its current
version in 1968.
SAE Test Procedure
Jg06a formed the basis for the so-called
California
Passby Tesk.
The California
Passby Test Is required
under California
Vehicle Code 27160,
for new motor vehicles under 6,000, gross vehicle
weight.
Tile code first became effective
in 1968.
It has been revised
twice since,
first in 1972 and again in 1973, when the current version
became effective.
The California
Psesby Test procedure
is defieed
under Title 13, of tile California
Administrative
Code.
A detailed
comparison
of tlle Cslifornla
P_issby Ter_t and the J906s
Passby Test will disclose
that there are differences
between the two
procedures.
Is actual practice
the differences
are minor.
Test
results obtained
by tile two procedures
correlate
extremely
well.
Walker uses the SAE procedure
as specified by their Original
Equlpmen| customers.
J986a
TEST
PROCI']DURE
TO conduct
the test, _ sound level meter microphone
is placed
50 feet
off to tbQ side from the center llne of vehicle
travel as shown in
Plgurs I. .The microphone
Is located
four feet above the test surface.
The procedure
calls for a flat open area, free from obstructions
for
a distance of 100 feet in all directions.
Under the procedure,
the tent vebicle approache_
the test section
at a at_ady state speed of 30 HPl]. When the vehicle
reaches
25 feet
from the test point, it is accelerated
at wide open throttle.
The
lowest gear ratio is used wblch will permit st least 50 feet of
accelerating
distance
without
over speeding
tile engine.
Passbys
ere
made unde_ these conditions
ill both dlrections
and the maxis%urn observed total sound pressure
level for each ps,sby
is recorded.
The
average
of thQ two highest observations
witbin
two dB of each other
in reported
#s the test value for tile vehicle.
The test results are
reportsd
for the noisier alde of the vehicle.
:
It should be emphasized
that tile California
Passby Test regulated
only new vehicles
sold In that *_tate.
It (lid not regular(: e;_Isting
vehicles.
Nor did it regulate
the
replacement
of noise-producing
or nolse-silencing
components,
nor of vehicle modifications
which
increase
the total, vehicle noise.
418"
20"
STATIC
TEST
PROCEDUI_E
Accordingly,
the 1971 sons|on
of the California
Legislature
enacted
Vehicle
Code 23130
which
regulates
aftermarket
replacement
exhaunt
ayatema.
The Col_mlissloaer
of
th_ California
Highway
Patrol
was
directed
to conduct
a study
to define
procedures
and standards
by
which
exhaust
systems
could
be cbrtified
an meeting
the entablished
allowable
total
vehicle
eoi!ic levels.
The California
iiighway
Patrol
commissioned
the HcDonee]l
Douglas
Company
to develop
a certification
program,
ntationary
test methodology
and related
law enforcement
techniques.
The study
formed
the basis
for the regulations
promulgate(|
is November
of '75 under
TJ tle ]3 of the California
Administrative
Code.
The
tent
procedure
adopted
lu tile code
wan the so-called
California
20" static
tent.
The choice
of a static
tee| procedure
was baaed
in large
measure
on tile ineffeetivcsens
of the driveby
test
procedl_re in urban
areas.
The coverage
attaleable
using
the drlvcby
test
in urban
areas w_u
llmited
because
of the lack of suitable
enforcemeat
sites
with
sufficient
open
area
and low ambient
nolne
levels.
The paauby
to.st wan more
appropriate
to rural
highways
or freeways.
Moreover,
being
n total
vehicle
noise
test,
it was unsuitable
for
regulating
replacement
mufflers.
There
was no simple
enforcement.
means
to ensure
that a cited
vehlcle
wan subncquently
made
legal.
The
20" Static
Test
Procedure
npucifles
that the tent be conducted
on an outdoor
pavement
or on a shop
floor.
A clear
open
area
arosnd
the teat site of only ten feet
is requlrcd.
The microphone
location
in dependent
sport tho.tailpipe
reutlllg
as shown
in Figar,_
2.
Typically
it is located
20" from
the end of tile tailplpe,
45 ° off-axitl,
at the height
of
the tnilpipe
chit.
The procedure
calls
for operation
of the vehicle,
after
a aultable
warmap,
at 3/4 of rated
RPM,
with
the traln|misslon
in neutral.
The value
reported
for tile exhaust
_ystem
in thn
hlght_'st rc_dlng
obtained,
disregarding
extraneous
peakn.
CORRELATION
With
the
STHDY
addition
o|! a
20"
Static
Tent
Procedure
which
wan
to
be-
come
effective
January
i, 1977,
it was evident
that
the
potential
sxlsted
for a dual
design
standard
for exhanst
system
development.
Accordingly,
Walker
set about
to determine
whether
there
was
sufficient
correlatloi1
between
the two tout l,ethods
to permit
the prediction
of nestle
test performance
ha|led on driveby
teatS,
which
were
currently
being
conducted
for Original
Equipment
prOdl|et.
The prime
motivation
for this
was
to reduce
the total
engineering
test
load
and to eetnhllnh
a single
acoustic
design
and
acceptance
tent
criteria.
Data
was taken
on a variety
of nnw vehlclos.
A
repre._entatlva
mixture
of four,
six,
and eight
cylinder
passenger
cars
w_:re used In t|lO
tents.
S
I
419
i
A number
of d_ ffeL'ent ty[_es of muffler's
were
tested.
These
included
tbe Original
I_quiI_ment systems,
_ith
which
tht.,new vehicles
came
equipped.
The Original
I_lUil_i11c:_i_t
system
sellle£imes incorporates
a
sxnallor
Iilllffler o_" _esouator.
Th_ system
is usually
In,de l_[)on one
or marc
_isuemblics,
with
the pipe
welded
to the muffler.
_Igure
3
shows
a typical
example
of an 0[:: system
assembly.
Welded
assemblies
are used
to minimize
the instal lation
labo_" in the car
factories,
Tile O.E.
system
is designed
of J986a
and the particul_,r
ns i£ relates
to tile image
to J,_L_t both
tile objective
c,lr collipaey's subjective
of the vehicle
in question.
requirements
sound
quality
Walker's
regular
aftcr11%arhet
Imlfflers
and
resonators
were
also
tested.
Regular
imlfflers
and resonators
are ,';old as separate
units
with
tile
system
held together
by clanlps.
Figure
4 shows
a cut-away
vlew
of
u typical
regular
after'market
muffler.
Walker
follows
the practice,
which
is comlson in tile replacemellt
exhaust
system
industry,
of consolidatlng
a number
of Origillal
Equipment
deslgos
into one after_larket
design
in ardor
to achieve
soma
economies
of scale
Ill prodsc i
tion
and to minimize
tile stecl:isg
and inventory
problems
that
would
otherwise
eziut.
Walker's,
if*deed
the industry's,
ability
to provide
tile consumer
with
all economically
prlccd
replacement
part,
on
a moment'|*
notice,
is heavily
dependent
upon
its ability
to Consolidate
O.E. Designs.
Tile eenst_'sctloo
techniques
and acoustic
design
techniques
of
Walker's
_'sgu].ur muffler
lille, is quite
similar
to tile Original
Equipment.
Figure
5 shows
u cLlt-away
view
of _in OE design
for
oomporluon.
The subjective
sound
qsulity
of the regular
lille conforms
to Walker's
own-corporate
standards
for preserving
the OrlgInal
Equipii*ont Image
of the vehicle.
A Cadillac
owner
ezpectl]
his
vehicle
to sound
llke
a Cadillac;
a Corvetto,
llke a Corvette.
Also
included
ill tile touts
were.
Walker'l;
WACO
mufflers.
These
are
s highly
C,,hsoli¢iated
lllle for certi*in customers
nueb
ns K-Mart
and
Montgomery-Ward.
The lille In built
to tile same blgh
quality
and
construetlsn
:fills(lards a:l the regular
llne.
J}ushlng
adapt_._s
llrt_
s_ed
to accommodate
a wider
variety
of applicationtJ.
On average
they
are slightly
smaller
in slzu
than
the regulur
afterl,arket
milf_ler
or tile OrigillaI
l','qslpment design
which
they replace.
Flgnre
6
shows
s cat-away
view
of a typical
WACO
unit.
Wmlk£_r'n
Unitized
lane
was
teated
as
well.
Tile Unlti_.ed
muffler
is s 4" rollnd tubslar
design
with
swaged
end_l.
Thin
llne
has s
r_asonably
high
degree
of consolidation.
Generally
it uses
a "Trlflow"
acolnltlc
design
(Sue FlglJre
7) and is not as efficient
at
tbe low fr_qtlencit;s becatule
of the sm_lller
phylllcal
volume.
Single
and double
lulled reuonatorn
are not used.
Tht,' IJultlzed
line was
Introdse¢Id
to satisfy
who are l;|Lerented
in
,
tile needs
economy.
o_
420
car
owners
with
older
v(.qlleles,
TI]o fifth
type of 111ufflcr lec]udf.d
in the to.sis were
glas:, uncles.
Halker's
glass
packs
also
employ
.I 4" rousd
construction
with
swaged
ends.
Ill external
apl_uararlce
they look
vez'y much
like
n
Unitized
muffler.
Acoustics*fly
they are qalte
different.
They
employ
n otralqht
thru design
_._it:ha concentric
perforated
tube
surrotlnded
by fiberglass,
as shown
in Figure
8.
'l'hedesign
is
effective
;it absorbing
high
frequencies
and
is characterized
by
a thL'oaty,
straigbt-thru
sound
q_in]ity.
Go|totally
it is both
objectively
anti subjectively
loncler than tile other
lines.
In total
305 _ystcols were
tested
using
both
the 20" static
test
procedure
and the JgO6a
passby
n_ethod.
Fifty-nlz_e
Ol'ig/nal
Equip_*ent systems
were
evaluated
along
with
II0 regular
mufflers,
50
IqACO units
and a colnbined
total of 86 Unitized
and gl;iso pack
v_rslonu.
ANALYSIS
OF
]_ESU|21'S
The test
data
wad analyzed
using
utandard
computer
statistical
•techniques.
The data wan o_amlsed
in a variety
of ways.
Simple
statistics
were
deter||lined
for each
test method
no(] each
clans
of nluffler
system;
that is, the mean,
tile range
and the atandard
.deviation.
The
simple
slat|slice,
while
not very
Isled'inn|lye,
are presented
in 'fables I and
2.
_aeh
class
of Inofflo_' and the total
po[_nlatlon
were
subjected
to
a correlation
analysis
from which
the
eort'elatlon
coefficient
WaS
determined.
A correlatloo
coefficient
of ace monna
a one-to-one
correspondence
between
the two test methods.
A correlntlon
coefflclan|* of 0 indicates
a totally
random
relntlonship
between
the
two tests.
The results
of the corL'elatlon
analysis
are shown
in
Table
3.
It is evldqnlt that
there
is no :]Ignlfleant
correlntion
between
the
two.
'l'|ledata
wn_ also
sub|coted
to a rcgreoslon
analysis.
From
this,
it best,
least-squat'ell
rolntlonsbi|_
betwce_
the
two test
methoda
was catabllshed.
The lack
of carrels|los
is
wry
evident
from
tile scatter
dlagrnms
shown
in Flgurcs
9 thL'n
13.
It can be seen
that
the predletlvu
accurney
of
the JgfJfa tent
in
abort| _+ 20 to 30 dbA.
From
_he analysis
ib In apparent
that there
are diffe._-'en_ acceptsacs
¢r]terla
required
for O.E.
and nfterlnarket
prodsct.
It Is
eveldenb
one
cannot
eliminate
the
need
for running
both
tents.
It was also evidQnt
that potentially
different
design
approaches
would
be. rsqlllrnd
for aftormarket
and O.E.
prodsct.
i
i
!
P
X_ al)pear_d
that
tile
Internal
eonstroctlon
of tile
muffler
affects
the relationship
between
the
test results
obtained
by the two
methods.
This
is npUarcst
from
the dlfferest
correlation
coefflcleats
for the reglllar,
WACO
and Unitized
mufflers
cosflguratios_.
The increased
correlation
shown
by tile Unitized
and glass
p_ek
1
mufflers
i
was
probably
attributable
to
tile lack
of
some
low
frequency
i
d
.t
¢
42r
}
tuning
elements
in
O0_lpollent
of exhaust
Ths
test
results
these
designs,
noise
is the
lelld credence
and
to
passby
to
another
the presence
test.
set
of
of
a larger
¢Olleluslons
that
can be reacted
about
the process
by which
the two California
laws
were developed.
A new vehicle
law was passed
first,
which
regulated
total
vehlcle
noise
wiLl|out
defining
what
the exhaust
:]ystem
contribution
to it would
be, aad without
adeqkLate
provislonu
as to
how exhaust
noise would
be regulated
on older
vehicles.
Next an
aft_rmarket
law was passed
to regulate
exhaust
systems.
The end
result
is
two standards
of acceptance
of ezhaust
systems
which
bear little
relationship
to each
other.
Perhaps
this could
have
been avoided
bad both
O.E.
and afternlarket
beef% considered
together
from the start.
Those light
vehicle
standards
have
now been
adopted
almost
without
change
by
the state
of Florida
and are being
followed
with
interest
by the state
of Oregon,
The ultimate
impact of these
tests on the
induatry's
ability
to continue
the important
practice
of eonsolldatlon Is not
yet fully
known.
Tile federal
government
is presently
developing
it now set of acceptanes crlterls
for [Jassesgur
cars.
This
one wlll
probably
be based
on a totally
different
passby
test.
We have
been meeting
)]ore tile
last
fnw day_
to dlscsss
yet another
criteria,
thls one a bench
test
suitable
for labeling
exhssot
system
replhoement
parts.
Tile
question
of oorrelatloll
between
these
two federal
tent methodologies
should
be considered
from the onset
in their
development,
The _mpsrtanet:
of conslderlng
the impact
of then0
now regulations
on ths Industry's
ability
tO collsolldate.
Original
Eqt|ipment
designs
cannot
bo overemphasized,
Shoshl
tile Industry
loSS this ability
and
tho number
of replacement
parts
proliferate,
the result
would
be Increased
englneering
costs,
shorter
produetlo_
runs,
increased
warehosslng
sp_ee
and higher
II%v_l%tory coat:_,
q'hc end result
o_ all
that will certi%inly
b_ highe, r prices
to the consumer
and potentially,
del_ys
on the part
of the InstalLer
in finding
a replacement
part
for his ons tomer' s vehlcle,
422
,ira
!
/,
Basic
J-986a
Site
Layout
Passby
Open
Test
throttle fully
A
Approach
at 30 HPtl
S0'
25'
Figure
L/
"_
1
-- Hlcrophone
_.
:i _
'
•
"
•
._
.
0
_
-
Muffler
Mean
Value
Type
O.E,
I_egular
WACO
Ul%itized & Glass
Total Composite
76,6
77,8
80.0
00.7
70.0
Pock
J-986a
Test
Table
Muffler
Pack
"_
Teat
_
Standard
Devlntiou
3.6
4.5
4.3
5.3
5.5
Range
LO
78.1
78.2
79.0
82.6
70.1
ll'[-92.1
95.8
96.9
105.4
105.4
Results
Correlation
Coofflcient
,245
.333
,282
.451
,462
Pack
An_lysls
Table
87.8
88.2
80.2
94.0
9;1.0
2
Type
Corre_atlou
71.7
71.2
74.4
73.3
71.2
lll-
I
Table
O.E.
Regular
WAC0
Unitized &.Glass
Total Composite
flange
--Lo
Results
84.4
85.4
86.6
92.2
87.3
20" Stntlc
Muffler
3.2
3.5
3.2
4.1
4.0
Moan
Value
Ty_p__
O,E.
Regular
WACO
Unltizad & Glass
Total Composite
Stnndard
DL_vlatlon
3
425
Re_|llts
Ho. of
Observation=_
59
Ii0
50
86
305
__,_i:
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POlNt_
DISCUSSION OF PROI_ED
81LI_(_
8AE I_3CO_I.E_D_D
P_Aff_ICE
]_,IT1_rIVI_I._
IN IIEDUCING_CIINE I_rl'AIcI_,
(311
I_IIAU_I'
_
by
Larry
Nel'.;on
J.
Indau_rle:J,
,_toughton,
L:
l_rik_on
WI
Inc.
53589
PFe_ented at tile
Onlte,(I
Brutes [_vlronmcntal I_tcetJon _gcney
Bur_o Trp_n_]porti_t_on
I_¢Iml_tI,k)is_
S_niT)o_i_
CJllcn{,'o,
Xlllnoln
Octol_r II-13, i077
(.
r
LIWh'L
Discussionof ProposedSAF.RecommendedPractice
XJI207,MeasurementProcedurefor Deterlnlnation
of
SilencerEfFectivenessIn ReducingEngine Intakeor ExhaustSound Leve]
by
Larry J. Erlksson
Nelson Industries,Inc.
Stoughton, Wisconsin
ABSTRACT
The developmentof ProposedSAERecoH_nded PracticeXJI207,rleasurement
Procedure for Determination of Silencer Effectiveness In Reducing Engine
Intake or Exhaust Sound Level is reviewed. Tills Recon_nendedPractice describes
a procedure for a measurement of the actual sound level produced. Successive
measurenlent
may be performedto obtainrelativeperformat_ce
valuesor Insertion
loss. Various considerations in the writing of the procedure are discussed '
and limitationsreviewed.
IN RESPONSEto a need for a standardizedtestprocedurefor exhaustand
intake silencers, the SAE Vehicle Sound Level Committee (VSLC) farmed the
Exhaustand InductionSilencerSubco_llttee
in Decemberof 1974. The objective
of thls subcommitteewas to develop"Insertionloss measurementmethods In
order to provide a ratingfor the respectivedevices." Since It was felt
that a singleprocedurewas feasiblefor exhaustand Intakesilencers,the
standardwas to be developedIn closellason_Ith theAlr CleanerTest Code
Subcommitteeof the SAG EngineCommittee.
BACKGROUND
Membershipwas soughtfor the Exhaustand InductionSilencerSubcommittee
(EISSC)from a bread spectruln
of technicalpersonnelInclodlngthose involved
wlth exhaustsllencers,Intakesllencers,engines,and vehicleapplications.
An organizational
meetingwas held In March of 1975 to reviewposslbledirections
for the Subcon1_Ittee's
work. Numerousexistingtestprocedureswere reviewed
at thismeeting as wall as subsequentmeetings. These includedSAE Recommended
I
PracticeJlOg6, Measurementof ExteriorSound Levelsfor IIeavyTrucksUnder
PracticeJI074, EngineSound LevelMeasurementl_rocedure,
and the SAE Recommended
43_
StationaryConditions,as well as procedures
developedby such organizationsas
the IndustrialSilencerManufacturers
Association(ISMA}and Departmentof
Transportation(DOT), AlthoughusefulIdeas were.obtainedfrommany of these
sources,no procedurew85 found to meet the requirementsfor a standardtest
procedurefor exhaustand intakesilencersas specifiedby the VSLC charge to
the Sul)con_ittee,
MAJOR CONSIDERATIONS
Two major areas of concernwere discussedin detail, The first was the
type of noise sourceto be used In the evaluationof the silencer. _non9
those consideredwere a speaker,a blower,and a standardized
engine. Finally,
it was concludedthat in order to obtainsufficientaccuracy,compatible_ith
other SAE Race.ended Practices,it_uld
be necessaryto use the aqtual
engine and silencersystemfor which the silencerwas to be applied. This
approachwas Ubaughtto have the potentialof providingthemost accurate
engineeringdatafor thesetypesof units.
The secondmajor areadiscussedwas the type of measuremen%that should
be made on the silencers.
Again, a broad range of possibilities were considered.
These IncludedInsertionloss, transmissionloss, t_ansferfunction,and actual
sound level. It was concludedin thlscase that in order to meet the dual goals
of a test procedurethat could be widelyosed As well as provideusabledata
that could be relatedto other meas.rements,tileactualsound level produced
wlth the silencersystem installedon A given engineshouldbe themeasured
quantity. It was furthernoted that the option remainedfor the test procedure
'Inthis form, to be appliedsuccessivelyto differentsilencersto obtain relative
performanceyal,esor to silencedand onsllencedcases to obtaininsertionloss
(ILl.
i)7
ADDITIOt/AL COtlSIDERATIONS
Other areas discussed included
the wide range of sizes of silencers,
engines,and test facilitiesthatwould be involvedin using tiledesired test
procedure. _/hiletim subcon_nlttee
felt tbat measurementsat 15 metres (50 feet)
from the silencerwere most desirableto be consistentwith other test methods,
it was thoughtthat otherdistancesshouldbe allowed in order to make tile
procedurepracticalforusewith small enginesand light dutyapplicationswhere
the availablemeasurementdistancesare often considerablyless than 15 metres
(50 feet).
It was also concludedthat tileprocedureshouldallow forioeaaurements
in a free field above a reflectin9plane. This may be obtainedeither in a
flat open space or semi-anecholc
chamber. Tim formeroffers tileadvantage
af a potentiallybetterfree-fleldcondition,but also tiledisadvantageof
_atentlallymore problemswith ambientnoise,wlnd, temperaturegradients,
andother weathervariables. The latterapproach,the seml-anecholcchamber
requiresextensivewall treatmentto obtain adequatefree-fleldbehavior,
butoffers bettercontrolover weatherconditionsand ambientnoise. In vlew
of these tradeoffs,the subcommittee
decided to Includeboth approacheswith
specificrequirementsfor both, This decisionalso resultedin data that were
morewidely obtainableas well as comparableto those obtainedusing other test
pruced|_res
usuallyperfumed outdoors.
INITIALI)RAFT
followlng thesediscussions,the flrstdraft of the test procedurewas
comp]etedin Septemberof 1975. It Includedthe above factorsaod required
an Isolatedtest cellcontainln9the specificengineto be used in the measureI_
meetwl_h an adjacentfree fieldabove a reflectingplane. The exhaustor
Inta_e_ystemwas
the9roundas
s_mllaras
to be pipedto
possibleCo
thisopen
the actualend
space'andapplication,The
placed in an orientatlonto
piping
43B
• _
, ,,,
from tho engine to the silencer
all contributions
was to be acoustically
to tile measured level from thts pipe.
treated to eliminate
This Has done since
some plpe had to bE excludedin order to connect to the Isolatedengine and
thus, excludinga11 of this noise _as the only practlcalmethodto standardize
varioustest facilitiesthat might be used. However,all nolse from the surface
of tilesilenceras Hell as the tallplpemust be includedin themeasurement
along wlth noise from the acousticaloutlet.
Thls first draft was subsequentlyextensivelymodified'
until finally
reachln9Its final form as approvedby the VSLC in June of 1977 and balloted
to tileSAE t.lotor
VehicleCouncil {IIVC)In Augustof 1977.
C0_IMEt_TS
ON FINAL DRAFT
Among the areas receivingconsiderableattentionduringthe various
revisionswas Instrumentation.The primaryconcernHas to o_talnsufflcient
informationto determinetilatthe engine_tasfunctioningproperly. The modgs
of engineoperation_Yerealso revle_edin detail. It Has determinedby the
subco_lltteethat the peak sound level could occur under a falrlywlde variety
of conditionsdependingupon the specificsilencer-engine
combinationbeing
tested. Thus, a steadystate and varyln_speed made are requiredalon(]_Ith
an accelerationtest for governedengines. Fast dynamicresponseof the
sound levelmeter was selectedfor all modes as provldlngadequateresults
with minimum potentialfor error.
The final verslonof the test proceduredoes not Includeany measurement
of the restrictionof the sllencersystem, lChIlethls Is acknowledgedto often
•
_(
be an importantparameteralong wIthmanyother specifications,
It was not felt
to be directlyrelated to the sound levelmeasur_._ment
and as snchwas excluded.
'
43_)
Because of the wide vartety
of test
set-ups this
procedure
_ppltes to,
it iS reco_llended
that a photo or diagramof the test set-upbe included_Ith
th_ test results.
LIMITATIOtlS
Among the IImltatlonsof thls test procedureare the lackof a direct
correl6tionto otileroverall vehiclepass-by tests as well as the lack of
speclf_catlon
of the subjectivequalityof the exhaustor intakenoise. Thls
aspectcan be quite importantformany applicationsin _hlch the overall
A-_Yeigi_ted
sound level i_ not an adeqtJate
descriptionof the acousticacceptnhilit.v
of a _i}encer.
4_0
/
/
APPENDIXA
_lembers of Subcorr_rllttee During Development
Afflliatlon
Name
*J. CaHll
(Secretary)
Sten:co Haaufacturlng
*P. Cheng
Stemco Manufacturing Co.
W, Dreyer
Walker /,lanufacturlng Co.
*J.
Dreznes
United Air Cleaner
*F. Egbert
h_ternatlonal
llarvester
Cm.
*L. Eriksson(Chairman)
NelsonIndustries,Inc.
R. Heath
WalkerI4anufactuK'ieg
Co.
R.Hunt
Stemco
Manufacturing
Co,
,S.Koehler
DonaldsonCo.
*K. Ligot
14alker
ManufacturingCo.
*K. ,Wowak
Cosmocon,Ltd.
_'W.O'Neill
FramCorporation
*R. Palmer
AP Parts Co.
C. Relnhart
DonaldsonCo.
*D. Rov_ley
l)onaldson
Co.
G. Shaltz
UnitedAir Cleaner
*D. Thomas
• . . w|th contrlhutlonsFrom many others
* Currentllembers
441
J.
Co.
APPE_UIX B
HEASUREHErIT
PROCEDUREFOR DflERHIIJATIOII
OF SILENCER
EFFECTIVENESSir_REDUCINGEtIGINE
itITAKE
OR EXIIAUST
SOUtIDLEVEL
XJI207
1.0 Scope - Th4s SAE Recof1_nended
Practicesets forth the instrunlentatlon,
environment,and testproceduresto be used in measuringthe silencersystenl
effectivenessin reducingIntakeor oxhaustsonndleveloF Internalcombustion
engines. Tilesystemshall includetileintakeor exhaustsilencer,related
pipingand components.This procedureIs intendedfor en_Ine-dynamon_eter
testingand is not necessarilyapplicableto vehicletesting(see Appendix
A). Tileeffectof tile
exhaustor intake systemon the sound level of the
overall machinemust be determinedusing other procedures. This procedure
may i_esuccessivelyappliedto varioussilencerconfigurationsto determine
relative effectiveness.
Insertion loss for individual silencers may he
calculatedthroughmeasurementof the silencudand unsilencedsystem.
2.0 instrumentation
. The Folloifln9
instrumentation
shallbe used for the
measurementrequired:
2.1 A sound levelmeterwhich meets the Type I or SIA requirementsof
AmericanNationalStnnddrdSpecificatlonforSoond Leve]Heters,SI.4-1971
(R197_).
2.2 As an alternativeto making directmeas,rementsusinga sound levelmeter,
a microphoneor so,ndlevellootermay he ,sod with a magnetictape recorder _nd/ora graptflc
levelrecorderor indicatinginstrument,providing
the systemmeets therequirementsof SAE Reco_nendedPractice,Quallfylng
A Sound Data AcquisitionSystem- Jill4.
2.3 A sound levelcalibratorhavingan accor,lcy
within_.0,5 dll, (See
paragraph6.2.4.)
2.4 A windscreenmay he used. The windscreenmust not affectthe microphone
responsemore than* I dB forfrequenciesof 20 - 4,000 Iizor _1.5 dII
for frequenclesof T,O00 - lO,O00llz. (See paragraph6.3.)
442
2.5
If outside tests are befng performed, an anm'_ometeror other means For
detennfnatton of ambient wind speed having an accuracy _.lithin + 10%at
19 km/h (12 mph).
2.6
A thermometer or other means for determination oF ambient an_Jengine
Intakealr temperature,
havingan accuracywithin_.lUC (+_2"F).
2.7 A thermometeror othermeans for determlnationOfofuelt_mperatureat
the fuelpump Inlethavingan accuracywithin+I C (+ 2 F).
2.0 A barometeror othermeans for determination
of ambientand engine
intakeair barometricpressure,havill9
an accuracywithin+_0.5% of
the actual value,
2.9 A psychrometeror othermeant for deterfninatlon
of ambientand engine
Intakealr relativehunlidIty,
havingan accuracywithin +_5% of the
actual, value.
2,10An enginedynamometerwlth engh|espeed and torque(or power) Indieators
havingan accuracywithin+_2% of the rated enghlespeed and torque
(or power).
2,11A flo_neteror othermeans for determination
of engine fuel rate having
an accuracywithin+_1% of the rated fuel flow,
3,0 Environment- The silencershall be measuredIn an environmentsuch that
resultsare equlvaIen:to thoseobtainedIn a free fleld above a reflecting
plane. Meas,rementsmay1_emade at a flat open spaceor.In an acnnstlcally
equ|valenttest slte as describedin Appendixl].
3.1 'Theflat open spaceor requlvalenttest site shah be free from tile
effect nf a large refleetln
9 surface,such as a bul]dln9or hi]Islde
locatedwithin 30 m (10g It)of eli,
her the .IIenceropeningor microphone. The area directlybetweenthe silenceropeningand the microphone shall be concreteor sealedasphaltwlth a total deviationof
+ O.Ogm(+2 in.) froma plane extendingat least3,0 m (10 ft.) In all
_Irectlon's
from all pointson the line segmentbetweenthe silencer
outlet and the microphone'.
3,2 The ambientA-weightedsound level (Inc]udlngwlnd effectsand nther
noise sourcessuch as theengine}shall be at leastID dl]lower than
the levelbeing rneaaured.
3.3 Not more than one personother than the ot_server
readingthemeter sha]1
be wlthln15 m'(50 It) of the s11encerepLnlngor microphone.and that
person shall be dlrect]¥behindthe observerwho Is readingthe meter,
on a line through themicrophoneand the observer,or behindthe silencer
under test,
443
p
i
4_,0.Procedure
4.1 Tilesilencershall be testedon the engineand silencersystemfor whlch
data wtll be reported.
4.2 The specified silencer system configuration
shall provide for measurement
of the acoustical radiation from the surface of the silencer or silencers,
connecting pipes, and the acoustical outlet of tile system. This does not
include piping front tile engine to the silencer.
The silencer system
should be oriented In tile same relative position to tlte ground as for
the actual application.
Any deviation must be reported with the test data,
/Ill system connections are to be free from leaks. For determining tile
insertion
loss, the unsilenced system shall hlclude a plpe of physlcal
length equal to the silencer,
4,3 The engine and fuel rate shall be measured at full load from 2/3 of rated
speed to governedspeed,or to rated speed on ungovernedengines,to
determine whether the engine Is within the engine manufacturer's performance
specificationsprior to proceedingwlth thls test procedure.
4.4 The engine shall be operated in tile followlng modes after reaching normal
operating conditions:
(a)
Steady state mode - rated engine speed and full load,
(b) Varying speed fullloadmode - enginespeed to be slowlyvaried
from rated speed to 2/3 of rated speed at wide open throttle.
For governed engines only:
(c) Accelerationmode - acceleratetheengine from Idle to governed
speed until the enginespeed stabilizesand return to Idle by
rapidlyopeningand closingtilethrottleunderno loadconditions.
5.0 Measurements
5,1 The microphoneshall he locateda(;a heightof 1.2 m (4 It) Above the
r,
ground plane analat a horizontaldistanceof l_ m (50 It) from the
centerllneof the silencersystem. Other optionaldlstancessl_chas 7.5 m
(25 It) may he used and must be reported. The anguIarIocatlonof the
microphonerelativeto the silencersystemopeningshall he recorded,
5.2 The sound level meter shallbe set for fast dynamicresponseand for the
A-weighted network,
•
5,3 For the procedurespecifiedIn Paragraphs4,3 and 4,4, report:
m
,
414
i
!%'_'mc!<'_
.3_:_!,
_, ._ ..!.
!T/_
:_•i
¸¸I.:
;'.
i
(a) Enginepower and fuel rate as determinedin Paragraph4.3,
(b) _iblentwind speed,ambienttemperature,arnbient
barometricpressure,
ambientrelativehumidity,and ambientA-woiqhtedsound levelsfor
the test site.
(c) MaximumA-weightedsound levelmeasuredfor each test mode in
Paragraph 4.4.
(d) Torque (or power), engine speed, engine intake air temperature,
barometric pressure, and relative humldlty at which the maximum
sound levelwas obtained,
(e) Any deviations from reconmlendedtest procedure as described in
Section 4.2,
(f) The angular location and distance of the microphone relative to
the si]encer opening,
(g} D_scrlptionof the test configuration,
including.al]pertinent
lengths.
6.0
General Comments
6.1
It is essential that persons technically
trained and experienced in the
current teclmiquesof sound measurementselectthe equipmentand'conduct
the tests.
6.2 Properuse of all test instrumentation
Is essentialto obtain valid
m_asmrements, Operatingmanuals or other literaturef,rnishedby the
instrumentand manufacturershouldbe referredto for both recommended
operationof ti_einstrumentand precautlons.to
be'observed. Specific
Items to be consideredare:
6.2,1 The type of microphone,its directionalresponsecharacteristics,
and its orientationrelativeto the groundplane and sourceof
noise,
6._,2 The effectsof ambientweatherconditionson tim performanceof
all instruments(for example,temperature,humidity,and barometric
pressure). Instrumentation
can be influencedby low ter,lperature
and caution shouldbe exercised,
6.2,3 Propersignallevels,terminatingimpedances,and cable lengths
on multi-lnstrument
measurementsystems,
6.2,4 Properacousticalcalibrationprocedure,to inelnde the infloence
of extensioncables,etc, Field calibrationshall be made in_nP.dJatel,Y
beforeand aftereach test sequence. Internalcalibrationmeans
is acceptablefor field use, providedthatexternalcalibration
is accomplishedIn_ediatelybeforeand after field use,
445
,
6,3 It is recommendedthat measurementsbe made only when wind speed is below
]9 km/h (12 mph).
6,4 It is reconll}ended
that a drawingor photographof the test configuration
be included in the reported results.
7.0 References- Documentsreferencedin this [lecomm_nded
Practiceare:
7.1 ANSI $1.4-1971(R19/6),Specification
for Sound Level _leters.
7,2 SAE J184,Qualifyinga SoundData AcquisitionSystem.
7.3 ANSl $I.13-1971(R1976),Methodsfor _leasurement
of Sound PressureLevels.
_flSI
documentsavailablefrom _lericanNationalStd_. Inst.,1430 Droadwmy,
NewYork, NY lOglO.
446"
APPENDIX A
A typical test layout may include an engine-dynamometer located illan acoustically
isolatndtest cell adjacentto the test site. Tirepipingfrom tileengineto
the silencer should extend from the isolated test cell to tlretest slte. Tire
silencer system should be oriented in the same relative position to tlreground
as for the actual application. All piping between the engh_e and silencer
should be acoustically treated to meet the reclulremnnts of Paragraph 3.2
The sound level measured durin9 the test should include outlet sound as well
as shell sound from the _llencer and connecting pipes, but not including tile
pipingfrom theengine to tilesilencer. The test sitemay conslstoF a flat
open space or acoustically
equivalentindooror outdoortest site.
APPENDIX B
If a facilityother thana flat open space (Paragraph3.1) is used, the
A-_P.ighted
soundlevel froma broad band sound sourcemust not dnvlateover
the testdistancefrom _he responsein a free field above a reflectingplane
nmre than+ I dD. Measurementconsiderationsin AmericanNationalStandard
t_ethnds
fo_lieasurement
of Sound PressureLevels,AtlSISI.13 - 1971 (R1976),
shall be used.
I
.447
r*
(_
A Theotet|cnl
for
l_,xaminatio,
Dyn_,o_tQr
of
T_Btin8
the
of
I(ul©v_nt
2-Cyclv
Parainctvrn
EnBlne
tluf[ler_
by
G.
Pro_Qaaor
_partraant
o_
The
Huchanical
Qu_cn'¢
P.
_lair
Enslnacrins,
and Induatrial
Uaivaru_cy
o_
I_clgnac
Ab_trnct
A powerful
nolea
thu
deaisn
perfoc_cnca
and
t)Te
uacd
Ilora
in
dynaza_cer
by
cogpmriaon
ixa_pln
i:
;_
with
¢o
uaod
and
nolution4
to
tim
thc_.
becn
dcv©lopcd
chnracCerLattcn
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tastinS
technique
h_a
r_otorcycles,
for
snovmobLlen.
coo1
la
uaed
o_
tha
nornml
effccttvenaaa
precina
clio
when
of
the
proble_e
thQ
ulaSn
the
computer
of
th_
of
an
un_cn,
muE_Icr
A n_corcycl©
lnherant
c,mpu_©r
or
_volved
©xh_ult
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program
oE
on,inca
par_matern
wlth
utll_z_cion
ncwra|
marinn
wrloua
ficccd
prcdtct/on
cycle
outboard
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two-stroke
ch_inn_a,
An cn6Lna
llluatrAte
Th_
for
for
_.n nuch
In
program
n
providin8
i_
pr©ncnted
_n an appendix.
J
44_
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u__;_,_._...._._._.
_ , _ ....
_o_,j0_,;._,_,_;_;__ ,
l.l
Iutroduct|ol_
Tile hit;tory
theoreticlan',
unit,
mu_fl_ru
tile
who_e
pOrtictJ_llr
_lth
of
aa
drenl_
or
_hey
that
the
an e_hautlt
cheerfully
I_owcr or
dcnl_n
a mLiffler
tim
au_lagoua
lnt0rr_latlon
o[
_ha hhmt
notoblc
truth
_xc_pctons,
po#'lClon
and wlocity
entara
the
©n_l/ne
and ic_
'_*yattm"
intake
ba
c_trl_d
out
_ha_
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d_duc_d
aa
power,
at
_o_
pit!Italic
location
a a_lga
t_m-stroke
i_
lot
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_our-strok_
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rived.to
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aml
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In nol_
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thermodynamic
!ha
of
ouch
and
tim_
it
course
tin_
a calculation
at
"_yatcra".
tho
eflictvncy
a©parated
bn d_t©rm/nvd
tb_
carl
thermal
th_
_ny
'_hat
r_ont
ta
detnilc.d
b_ nvahlat_!.
that
no _e.ntion
or
npork-ll_ition,
or
in
chcgr_cttr_tico
chang!no
call
their
will
wltl_
_ro_
ter_
at
of
Yct
have,
io
c_m_umptloa
#ourc_=
©_©ct
or
of _a
can
detailed
ecctioll
the
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l©val_
ll)_lyo
de_|sn
of
pc_r_o_manc_
air
laced
obvio.a,
The "_y_ttW
l_
or
parcel
thcor_tical
_llencer_.
_orllc
c_l_tcd.
type.
particle,
for_8ol_g
cycle.
latter
trot!aS
mid p_rformanc©
th_
the
too
their
np©_d and
then
noin_
b_ noted
raciprocattns
nor
In npacn
on both
will
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proc©durn,
o_ gnor_t_
It
torque,
and
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t_rf_o
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and eshauat
dealred
lrl o_liin_
hatl
tile
part
barely
in all
©wry
_nd ©xliauat
It
pac_do-_cou_tie,
chc _ngiuc
l_av©_
of
ia equally
include
that
with
_ilellCCro,
SCratch.
aa
_thcrnaClcal
it
cnglrlc
rarely
aml
attempt
for
until
_,c.
tJllerlcer
rico!goers
the
pvrforiTl_lnce
[hllted
8coop
i_
it; pcl_pvrcd
[_rctell_lOllt_.
co_poncnta
to
o_at_,
intake
o_
failed
n_m_ly
tile
In _couutic,
that
on reallty_
of
efficiency
thenv
baaed
tile
dc_l_n
intake)
t_rm.
ia
in
fo=_er
(or
_n/lluc
_l©ctricolly
to
ellciale
predict
Th_ Ili_toz'y
iib_olute
_©ometry
for
i0 to
_tth
author
d_t_a
c¢)rtLbarJtion
referred
otaaxQd thia
of
it
type,
arc
th_orct_e|an_
internal
nncucally
'o_ mlat©ad;_
has
b©e.. mad_ o_
rot.ry
a_pl.raC_A
ISan dynaralcn
or
_n_In_i
ora
ao
clttholie in itpplieation ao the p;irticlel;of nir are noll-tLect_irinn
oii
the topic o[ into which
2.1
enl_iI_ type tht.y _dmouldbe iu)_e,JLed.
Th_o.ry,
CoIhpllt(.'r
of
performance
hilt
not
and
exhauot
ia
n report
noi_
10aued
B tile
thin
input
tile
and
have
cor0tnon cyp_
th_
thirteen
ye_r_
(]ueen%l
calculation
whinh
One of
UI© v_lottl
for
of
the
tim
llvt_l
coropntur
b_ #_en
cylinder
en¢ln_
petforn_nr.e,
in
tuned
cxp_nnlon
indu_cion
tll_ir
pinton
in
_erion
_he
_¢hln_
_old in th_
United
llnttng
of
th_
_nt_ndnrd
cov_ttd_
I_or tlltl
tentltl8
controlled
mtd
_ctu_tl
t do,in
dilt_
in
nnd
ill t|tltt
£or
b_ imcd
will
muf[ler_
on
their
ll_ttlr_ll
portin
c/lhautt
with
it uinUlo
u_,_d in
'enduro
M_own in
th_
enBin_
451
It
burning,
of
lntnke
"_yBte#
nppendia
over
_mthod _
_.PB2 dencrihen
with
d_t.
St|tt©u
lit
inlet
but
_y:lLcm
=llencer.
(;PB2,
proBr_tt_
[or
r,h_ last
_ workin8
be vt_rbiose.
|mr_orm_lnc_
nppendi_
el_ll_ult
boxoa
with
Uo.1096_
hct'HecIt I_/t#llr_.mcItnltd
wouhl
_ type
report
_ork
computation,el
Imrc
_##oclntld
the
with
the
there
8(!Ol_Ct_/ _or tile
reft.,rcnce_
l.l,
itlt_kc
paper
_ptcie_
_everM
in
8 the
811_oline
trod thcort_ttc_i
proBrntnn
rl mc:,,inn of _v_lu_ltln[i
A_ cnn
The
ol" correlation
dinnu_ion
Uei/nut.
illOtlt Co_lplcli
enBine.
now ju_tifle._
p_oblenm
tile
[iutcd
n calcuhttion
cy_l.12 en_ln_;
all con
i.e.
to thitL
of
'Juch
typt,m
:lpnrk-i_nition,
_p_t'imentnl
FurUl_r
tool,
from
tht_ dt!rivlltton
to derivin
_lppendt_
Univeroity
dlltn
[(Ir
enl_ine
c_tended
the
aspirated,
bn_kBround
_nd
been
lit
output
n.turall_
d_#crib_t
v_lu©_
tl_e
muo_;t of
created,
from
cnn bc c/trefoil
wlvin8
four
for
COl_ilrllClllion b tt_o-0trcJll[-'
crlln_ccttl_
_
been IH;ll_lllbl_d
_oluti(mo
_pectrn
ninsle-eyllnder,
d¢nlSn
IIIId h_lw_
chnrncteri_ticn
ninny o_ th¢_u
d_uctibin
for
C_lllj
prol_.ralli8
tot
_ or
FIB.1
form
h_r,_ to
llln#trnt_
it tl_llnt_m_t_r
_,nvirollm_nt.
n typical
ninliln-
G _ud hnvin8
eilencer
a
conni_tinf
e_pnnston
box
nn e_lntin8
_dc0ort'
of
typ(t
250
cm _
rncin&.
with
ccrtnin
port
o_
of
_l dt_lRlt
of
A
tl_
developed
_
lit
(_U]J [or
[I ll_lrLlctl|llr
cnnfldeutiality,
hor.epo_r
_XthJ are
cotu;_qtR.tlt_y
Al_;ouhoun ml FJlI,
I i'Jtile output
2.2
'_'IlU{I['_{:iE_II
2.2.1
Nhell
nomenclature
IJ{)ltltl.(Hl_
I_ll_illl_
a motorcycle
_[Lhilz
l;{]lll_
lfl
[]Eo[lZi!Ill
_lr/Jll_l
beil| I" tetJted
ol1 II dynalnol,_eter,
dylltllnO/ll_i_r,
l_etlt llrcil0Ollli-'llil
tlOIhC ZlCOIHICIC Cover
_hctl
_
_1l
lll{:lll_{_
I:eco_([
(!_l_|[lflt
th_
/l/ld
of the I_ylnbolr_
t_utt_l_at[uttu
III_chiLtlIC_L]
o_
_he
IlO_t_O,
In
1_
vdl£_ou.q
_11 the
t|le
provided
ItO[ac
W_l:llolit
either
chaati[t]_ atld a lilicropholle [t_ I)l_lCed
it'J l)rodoctlon
_JOlIl(3
i,'iven I.n the alq_endi_.
i.
tO
o_
[or th_ peak
npccd of I11)00
rev/miu and the descrjptJ.on
_md the data
or
IlNllltl[_lCLil['l:r
for
it
_OLI_CC_e,
ilO111(_llClllture
_or
II_glt_]._
p['o_t'_lfll
CPII2the _11crophonc_tlEonltlollcdac dlscanec _PATIIIand tlPATIIE [tom the
_L_e
ltt_d
111/ _0
i_o_t_'c_a, The
i=_hlttttl_
Ilo[_
ITIoch_ll_Cil]
IlO_t]e
l_rol_ri_Itl
prov_dt_li lto _¢_[0_J_0_1
IcVe_llo
CO l:he dyzl/llliom_cr illlileilllf_etl_
Thi_ Ilo_ili_b|i_e_[li:r_r_cncttl_()|u_:_oII
acountlcally
,'q_p_l:
Ml_eld
the
otl{:aLd_ _llll_
RPATIII_ [rom
th._
Blt_ld
orlIlce
A thcori_/c.l
_ltt(l
by
comp.rl_on
wLth
no[he
llOlli'Cull
Ulldcr tile
t_,c
tile
hccomc,
lulnmhlntlon
3.2,1
t©,C proc_d,rcn
cnC_re
tlm
te_t
nri_a b_t
have
poalt[o{l_,lH_ o[ the
a 1_nn
o[
crltlcal
In_ulc
Jollz_ly
colzdltlolt_i impoi_cd
7,5 or 15.0
nir_tent
method_ uf
mLcrophone
ra c,lploycd
at
[.ccor.
l,ounih_lltJl,'_ .pp¢_ra
thc._
oot,_
,t
tlli_ezdiautIt oriole©
by
lntal;_,
.¢ction
_n
mzd e_llno,_
by Icypicnl
ilccclnlc_tlon
by nevernl
auchocI_i_a,
2,2.2 On_ o1_ the
tile
lntnk_
or @._Jllltlt_
ecoloRtcal
and
d_/Idvan_al_c
el_Icl©t_cy
dtltnrloracc
.yntcnln;
In
tll_t,
silencing_my eugln¢
thJll
ban
alin<_nt
the
dcvlcc l_ to throttle
(l_ntinct
cccta_lliy_
rcnpecl:lvely.
or otherwl_e of Cilianl_proach In illtlcllaflcd
l_lln
co_n_.rclal
ctl_[oc
An cm,minnt[on
In .ecttoll
p©r£or_nc_
of
the
_l_£ccl:lven_n
3,2,2,
_52
N
,
f
2,2,3
Under nccelerlttion te_t cozld[tlnI1_}
oI_ _ltr_z_1_tile veliicle [)a_I]estllrou}[It
']'Ize
LlieoCuLicn_ proljrnnla|lows one Lo u1_nlnii_u
in delhi| tlz_'pur[oz_.ztlce
_nd noJLue-npeud _puctrlJlnIn dutlill nnLi [}e£1_Ltutile cedeI_i_n o_ thu _i]encur
no u_ to e]Im[nnLe LiluwocnL noIiiu c_[ui!_L _ ]_cLicli_nr sp(!_| po_n_ wi_l_oLJ_
r_ducln_
Lhu ovucnll un_in_ lJUCfortiLnnce;
[_c iL i_ LhIIL 'wor:_tI llOlSlu
point which
wJ.l[ _eg_ntur on nn nc_.ulerntion LUr_L. Solnu cider0 o[
motorcycl©a
hltvu d_l_onuLrnt_d Lhu_r nh[LILy Lo r_'c_rd [o_er
ilolrm vn].u_a Ul1_U_ nc_u1_nL[on
_h©Ir inn_ncLivu
either
well
point,
nnd Lh_n i_ _innn_ed by
ab_IL_y Lo t_o_| Lh_it 'wofuL' nni_u-_pe©L! lloit_LLu be
be[ore
l"uccher
_u_L cundiL_oHB
(by I or 2 d]l)
or wull
dincu0_lon
t_[ter
the
o_ _hi_
minimlJm micrnphone
La contnlla,:d
in
_o m_chine
_ccLion
3.2.1
dia_nnc_
Wllet'c
_C_LIA] _A]tIQg _I£¢ _LIO[_C([,
2.2._
On_ o_ Clze dl_[]¢ta|_
-oth©_w/ae
*_[ ,_n _xlaau_
nml _¢cei©r_Lion
_,_ploy_d
ltuue_fimezzL [_rohler_u
_zzfEie£,
Lcuck tc_tinB_
Jn _h_ prnn_nce
[:0, o_ _
il_ ©Xcea_ o_
cor0z_,_ntn ,_pply _qlmlly
oJ_ Lhe th©o£aC_cnl
pl_edic_Jona
_ro_
{:([unlly
cF_l_i[Is
to m,_chnn/cnl
el_nmlnnL_on hu£ct.
nol_e
level
lo
_g bu_n_
_h_r
©q.A1
/FOT_ t:tie C_llnZifl_ _OUFCL_, T|le
nolo©
but
[)L_c_nLon
p_rn_r.m CP_Z I:o nnnJnL Ln _n
453
_hich
OF
to dynnm_rn_L_r
ta when _[_ exhm_o_ _z[Zler
f.c_ nucr_Lon 3,2,3,
l
LO _hc e[/_Lvenc0g
nnd it nppZ_e_
of an tntnke
_|1_
_
thnl; i_ o_l:a/de
o[
cllJ.a prob|em
[ll_lminecion
nro
_roo
_h_: ncopn
wJL|l
prcncn_ed
Dincunnion
3, L
Tile
information
avi|[Ii_tllc
pre_untcd
[roi_
highlifihtlng
2,2,
3.2. L
L to
the
tile
huru
ocv_rltl
[_eneral
in
but
¢olnplzter
nature
a abler
fraction
rLznu LltVolved
of
potential
of
the
total
Lil l|Ll]ncrlcally
probl_mu
in
sectLonu
2,2,4,
A tlufl_3ry
pcrfor_¢zncc chttractcrlstict!of the cnflLBc
of !ha;main
ahown in FIg.2 over
the _pced
i|r_
range between 5000 - 0OOO rcv/min which
would be that employed
for n typical acceleration tcstj Irrcnpectlw
microphone
,ztd test conditLona.
poDicionlng
both Qzp©rlme.ntal and theoc©tlcaL
power
Th© theoretical valuea nrQ predlcted
data in Fi/l.l and the _xpcr£mental
tim ©nEin© _nufacturer|
hnva
npcclfic [ucl conoulnption (Ib/hp.hr).
by the prollram CI'I_2for the listcd
or rncnmlrcd wlluen were provided by
The ensine
ia runnlns
st
prcdlcc_d
full
"AccaL_rat
ion
thro_tle
noi_© tent.
_hQ th_ur©tlc,l/©sp©rim_ntnL
Test*'
The contrib_tlon
noi_
of the Intak_ and e_hal*_ no!he _ourcr.n to thu
L©v_In at each _pced point on th_z 'acceleration* ta_t
are _hown in Plg.3, an pr©dlcted
of iS.0 m [or both _o,rccu.
a_ dflawhil_
thcor_tle_tlly for
mlcrophon_
po_Itlon_
?lle noine L_veln on FIB. 3 arc COmlnltcd
th© cq_lIvaLcnt data for _h_ same nlc**ntlon buc with total
lcvnl_ calculnce.d are plotted z_ dBLLH on Fllb4.
that th_ intak_ no/nn
i_ lower than tli_axhnunt noi_
It can be _ee.n
in acn©r_l, b_t
S
han.two quite dJ_tlnct peaks at
noted
l
_
her©
Im qt*it_ 8ood,
correlation
noi_
for
and on the rn_ztaurcddyt_otest data# aml am it wolild
be for an accQLaration
owrall
apeed point
thuJ not all thcor©tlc#l[ valu_
a mt_nmlr_d cquivnl©nt.
both theoretically
Presented on Fiib2 are
valuta at each
(bhp), d@llv©ry rntlo and brak_
of
that
the
p_ak
exhauat
5500 and 7090 rev/min.
noiaa
ore.ca
454
at 6500
It will be
rev/min..The
7000
r_v/in[t'L s |.rr_upc]_l:|.w
tlt_a nr
I_|_|L,
I)I_LIH c_iLeri_l.
pcodtt_(I
a Lot;ally
A Teot
HLlffler
of
_ed
'_, ju_.
ch_'_l_f_c_l_l:_Lc
dlh_
_h= pulik
_o_" Lh_ lt_.LJ._!
rev/m_[n
_hl_
nJ.lcncer
Lh_ p_ak_
thnL
=[l_ncur.
i_©rhnp_
_cnd to
The n_Lt
the
o_ nol_
•
tile
_p_ctrn
_= Che peak
lnl:ak©,
i
[lluf[|er
i_ to
b_
|_ll_ _l no(oe/l_peud
th_tt: the
lllld |)_h_ce
c_lrr_l_L
|_
hil_lle,_
tenL i aln_o_
_lt
(_bo{) r_v/mLn
peak
n l)_lk
it_tnkc
no_.nc
v_l_m.
I)ol_._
certainly
[or
_L
exh,_l_t
nnd overnl|
_n I_e|ec_edo
7000 rcv/min
Cn_l|==_c_l
I;o'_t;lona
:_u_e
_p_ctrn
Preticnt;
_-tl
_n t:h_
Ehat; t;h_ pr|nc_pa[ _totlrc_
[n the _hntlll_ nn_lle i11=ccCt,
urff
between /_0 nild 700 It_,
go_=_ p¢_=k would
¢lle
no_c
=¢_yn
very
rt!_tl_,l_{I
ren[du_]L
_lnt
ill
retail
rnpLdly
2000
Itr.,
It nct_Ln[ned noise
¢o b© tnckl=d by
of the u_Ht.
455
nL|lerwine
1¢ cnn he _¢_cn t;ttnt:
rifler LOOO lit, wl._rcn_= Errs!
'£hc_ comt=_nntlon
_ourco wJ,t;h
apnct;¢_=m__ll_|UClIC_=I
Lit=ov_=ral[
=hould be t;Im_r=quency
'¢=l_,enI:In nny r_d_fin
A d_,]) at i_h_E po_LJolt=
hnv_ benn ev¢:n h|llh©r.
=specC:rutn [allu o[{
t;wncharncEe_t_c_
_11_l_krn
_y_Leln i)n'_ud
;,_1_1noL aL the
coincidu
[)oa_(:_o{t
J;_:omthe
Eh_ ovr, rn_l
_.n_nk_ _p=ctrum
_l_n_ut_ment
_l_tv[ce
wou|d
LII_IE_the
whe,lc_aa Ett_ J,l'lC_ke llO_Lft= MI)_-'C¢_'tlF_
hi_
_ln_: overa_ll
lure1
_ccordc_l_
predictn
t;Ite nolo©
e_hllu=_
at: a t_il_her
e_llau_t
ruv/mLn
"_cc_l_rntJan"
CIt[CtlRE[ORrl _ctt_ae(| nt)ov_, It:
i
ir_ qulLe
Lh4tn _11_ 0Litn_l_lr_| ull[L,
off_c_
would
nt; t4hnL(_v©_ _ndep©nd_n[_ ;n[c£op|lone
l_
inu[_ler
_llLerttnt|ve
wt|Ll_
2dB hLBi_er
B_
foc
n_ 7000
[Io[zltn
Lhen [_sLl
Th© proBrllm
FL_.5
been
l_y
occ_lrr_d.
LhaL _1 iluw
lh_._
In |_dk
occur_
ilol_o/_|)ued
55_)
[Irob[c_l
Let: u_ _u[Ji_o:le
11o hil]h_r
b_t;
_Ln¢| c_tlnu_t
t]aw_
n_cor_3
no_l_e/llp_(td
l_ illo[n_n[: t:haL [:he zJhOVC de_nud
nt'_d [.t: _.l_ _olmd
7_°_
noitle
wou_.d have
IL [_oi:eiltial
[eL u0 _Lr_r_Lu_e
_or
"t_L
up_cLrunl
IIII_Lq'flaL 't exh_lolJt
Lhe int:_lke
:lituatlotl
tIOil_L_ rL_cordln_
ProbLem
Tho k_lcn_[
th_
tim
no[ILe/:Jp_d
by n nottJier
_}hou|d
dJ/[erct_L
. Iicther
Thu over,iLl
m_tinly
chnrLtcl:er[llLlc.
hcr_:
of
_1
of Lh_.n_
_14it_Lv_[y
_o¢liH| _|_Vl_[=tile|
(=s_y) n aultnbia =Idc r_oilnLor
!
i
Hicrophone
Pouit ionia[;
In a dyn_lmom_ter
noi_e
la not
record
nhlehlcd
(or attempt
poaitionln8
_hcrc
tent
_ituation
[rom
the microphone
to record)
the
the exhatmt
becomaa critical.
intake
(and
_¢hanical)
which
in bein_
noi_c
then the microphone
The reh_tively
u_d
to
obviou_ conclut_lon ia to
[)lace it au clout to the c_h_luut noitie ot_tleL au i0 practlc_ll.
thlQ imilzt iu made i:_ FiBs. 6 lind 7 In thu
to illu_trat_
data
and in l"ilbO no a _raphlcal
to
(dSa)
the
it|Cake
moat
the
ca=©a
_or dyno
of
find overall nollndprc_u_e
microphone
fl_ld tile
(RPATIII)
lo
nol=_
la
=gamination
o_
nattily,
_h_ elonar
one
l=wl
nearly
cointl4©.
e_ha_at
th_
ext|uaat
(c)
in
placed
The curv=a
it
le.vnl
FIB.6,
of
th_
noiae
in
no'_=_
and
[or
microphone
poaltion=
on Ylg.8.
equal/equal
r_icrophon_
poai_loning
_orconatnnr
eq,al
nolae
2d_ dif_=r©ntial
l¢.vcla
_rom
456
tim
both
the
that
l©val,
th_ raicrophona
nolo=
overall
rnierophon_,
agalnnt
oh= pc=rgormane¢
Independent
approxlc=a_aly
poaltioninB
FiB.6
ohvlo_m_
with
o_ tim
poi_e at varlou=
b'hll,_
in
=xhauat
the intake
nutl©t
raitl_i_te
lcvela
tim
rolntlv=ly
ponitlonin_
wo_l,I
nhohm
to
than
=:ahau=t
r_pr©ncnt
will be rerp_mbere.d
owrMl
th_
to the litlet
is
clo_r
relatlw
(_P/iTIIE),
ra to
ait,ation
revcnla
a l or 2dll di_=reaee,
l'ot_tar.
15,0/15.0
ponitionlnB
approachea
ot=tle_
0.5 m nearer
rev©rne
flB_*r©a
pouitionin8
c_{lau_t
or
more. loslcally
do== th_
(b) or
o_
The
Time any ear©lena
a= poal¢lonlns
aa_easra_nt
7.5/7.5
=om_ 2dl_ 8r=at_r
A clone
raore
and
microphone
=qual/©q,al
cahauat
work
©qulval©r|t.
th_ microphone=
At
th=
combiaationa
=ource polfl_
ncc_l©retion
what=
the
a_vural
c_hllLiItr
th_ relative ponitLonln 6 beilz8 moatly
with
in
for
form o£ tabuh|r
rcprenentation.
Ill_I_.6 i# _howI1 th_ i[|cakcj
levela
An attcnq)t
any cl©ar
og
an_ particalar
Intak_ nnd =_ha_|at
aru
ahowa
producan
differential inc_
_oure©=
a,oh
together
_a
mlcrnphon_
q=_= with
di_ttlnee,
tho
[n
OtllOr
dlffercntJal
Villuc
but
wordtl
£1t |m+Odll nolae
|evel
frolll
l}oLh noUtl2(++l
llO0it:ion_.n8
it* 0.2
m at
about
microphone
lea
?Odll eqlllllity
the
dlffcrolleinl
nl)nctnll
0.75
l+m3.2
m median
m on a 12.3
In
nmdian point.
pooitionin8
Clone
3.2.2
of
n©eaalsnrliy
rcqutr_
dynamometer
trot purpo_OOo
Thro,ttltn_
[ho
The
deai/_n
the
time microphon¢:
h'xh,tt,tst
tout-box
in
vnlonma
tile
nl_ieldlnt_
of
exhauuL
other
outlet
would
:lot
+Jouz'coo for
iloiu_
O,_tlut
nllencor
dlacunucd
different
ncountic
to
un_d
tile
in
ilrcviotl,
connected
the
relatively
ueetlnnn
_,ImpIo
hnn
nilencor
banicnlly
by 24 r_nmdiameter
ttlbea.
four
The
elemPtmta
or
ealculJition
at 7000 rcv/min +<nnrep©ated far n microphone ponitianln_l of 7.5/7.5
eqtm+_l/W
It
w_ll
the
of
dintance
DDI.
DDIR,
20.0
to
22.0
and
rm'a to
but
,
th_
ta
mor_
1,5
of
althoullh
nol_e
Jneren.od.
rmn vnl,m
air
_low
. ,,j+p,
ttdle
on
time d/amctern
lfi,O
to
1B,O to
original
diameter
atandnrd
wan
nte|_..
conut+ml)tion
exhn_#nt
outl=:t
ovorall
noi._
Imve.la for
ovnrnl_
Ln powP, r and
457
i,
tile
Tim eqm_l/t
22 ram; her© thn
the
the
reducea
no_trc©.
/'roe
bein 8 the
final
point
etmnl_ed
The
ronult*
lind ©I¢hnt, ate
Fl_.9.
throttllnfi
holo+_ th_
noino
calcnlatlonn
Ln aev=rnl
npcciflc
nhc_+n on
hp p_nnlty
_ignl(lcnntly,
nliahtl7
otltlnt
certainly
predominant
dB J_or 0,5
the fint#l
renpectiv©ly.
hl+_bent
five
of
vnl.e
brake
that
to
wan the
l_tter
2_.0
noin+_ arc
no doubt
di=metnr
wnrdn
tniet/outletn
chnng+ed fJucCc=nively
into; tim
t.ntio+
n£Gnificantly
the
r©v/min
In each
mtnndatd
2h,O mQ diamutcr
tn outlet
l
26.O
other
And overall
beco_ea
Juot
to
dolivery
pm+nrp
Thorn
_rom
7000
and e_llannt
character/nile.
In
16.O
lntnka
that
DD2 lind DI)2R worn
enleulntio..
for
intaka
I)© rcmolahar_d
not=e/opted
_rom
Erom
m
w_a
the
7 el
int+lk_
r+oiao
induced
to
16,0
bl, home
4dBp
nolnn
level
|l_)inelevel
non_
down
which
occura
now
at
in radtJced
_n fuel
corm.option.
by aom_
2_ tile
i
n
intak_
lzy
Further
power
throttlhl_
(6 hp),
barely
whet©
thu
It
while
outla_
ueen
tn overly
power
nnd efficLancyj
Th_
d_v_c_
enl_lne
flow
r_lte
lnd_ed
tt
nct:ually
tha_
on
th_
io allowlnB
3.2.3
©ffLcl©ncy
tim
tsomQ I5% tha
.intake
aatscnamcnt
prosr_m
_ a dt:vtc©
en_lr_
bc
:sy_t©m _'educl:o
and
cnpnbl_
_n_lne
ltmL¢=
pow©r unit
ou_; imrt_.cularly
{ror_ I_|1_ axhmlp_
incratloed
_t.th©
ao
of
point
aa
©n_ina
_att_Borl|:=d
_o produc_
nnd
both
a= nuch
d_[fft:r=n_ia¢|n8
it=
_he bndly
[:o fJ_
b©_w_cn
r_t_d
d_Jignld
within
a
elm
pa_r
or
producad
lagiala_:_w
dnyn ratnntlon of hi_lh _nglne
l_ nw Lp_o_tnn_ na ©xc©nalv_
t],_t th_ noin¢ p_k
b=fc
in
by ldB
In accCJon 3.2.1 tlte i_portance oE _he d_Lgn
wan poinl:_d
by
drop
Lncr_aaed
_rm0cscork. In th©nn ecoloRienlly-conac_ou=
I_lmrr_l
(tim
decrea=ed
r©coi;nf.aed
th_
thr, noitse
,,d_Lch dnrnt_a
e_ficl_ncy
in any raufflcr
r_ethod.Q ahould
withLn
a conoiderable
_nu 20 n_.
and r0u0t be
uhtch
and c_{J.cL=ncy
produce_
air
rea_rlct_ve
_cnt
=llencer
_
in
diameter
which
the
th_
altered,
c,m b_
duvicu.
16.o
a deterioration
by rJollm IO_);
iioLae
to
nolnQ.
o_ the Jnr.nke a_t©nczr
_n_phanL_©d w_n tho n_c©n_Ity
t:o en_ur_
in tha Intak_ np=c_rt_n did not colncLd¢ wLth
chnt
ay_tc_n.
On th_ _nt_nd_rd '_©ngin_ tim In_ak_ box_ _ox I_ had n volur,_ o_
7200 crn_ _ll:h
_ _0 r_n ouLl=t rub© dlnr_cnr
Till;= wa= _laced
{:ubn of
/_/_ _
prod_ca
l:tm_arn_ total,
po_r
dlarn_t_r
tl_
from
angina
"pap©r-enR;_n_
J._ uncleared
I
i
h)' _ ar_nll=r
box_ Pox 2.
o_ th© aar_.
l©nl_¢h.
nit
7000
_'lth
flow
at
Th¢_ overall
of
PSI - DS2R).
2500 c= _ volt,_
Thi_
rcv/rain
a comn_on "atnnd_rd"
cn_|lt_r-dynamora_t_.r
In
(rilldla_t_ra
nnd n
wa= no _rrnn6ed
and therefor©
_xhnus_
tn_t n n/tuition.
_e
th_
aam_
aZatarn for
oach
_h_ =xl|_u=t
nolnn
coneequenct=.
nol_
_ra ahown
In _g.
lO nnd
lncre_cd
ovnrall
aou_
(intake)
l=vnltt
th=_ first
pren_p_r
point
lawl
450
'
_nd the=it
fr=quenc7
to be. obl_[v_d
pe._k (dlSl.Itl)
I_o
I_
_p_ctrur_
r, rentl_
_'t the= _ll_#l_
Imnno, ic
(116.7
IIz).
ozl_ hnn 8rnve
thlo
It
doubta
freq,_ney;
pe_kk would
_lppliclzLton
(,or.
2) intaku
tim_
O.6dn
to rccanaLdcr
(d_l.I_)
of
.hould
one mu, t obzJerve that
thc ^-weL_htin_
one ride
_Ll_ncer
hL_her
tl,m
witl_
_tafzd
che
producen =tt_ ovttllll
doaifin,
o[ n toLnl
at
low frequency
Aa the {aria
th_ orlfitna[
Eor leGl_latLva
factor
a motorcy¢l©
box ch0n thta
chnrncterL_tLc
Lhe _pplLcation
crL_rLa
th_lt
lind unplen,lmto
o_ th0 ^-weifihLlnl_
Lt
levvt
thaL
im obtr.aLve
Eor Dox 2 only
poLnt
le_ittmtzcy
bc aoaured
level
i.
thin
I_bout the
[or
auch n replacement
noi0e
(o at
aound
l'©rilnpa
_ot=nd pre==uce
purpoa_0.
Conc luB[ozza
Tha th_or_tLcnl
d_aLBn tool
the
whLci_ ia
n_pnrnte
_e_,men_
on th_
Jntnke
pointa
_n_lne
that
in
illuecr_t©d
n tr_©
nnd exhaunt
_
w©lt
_nd ira
_h_ program
nno_m_oblle.
i)roc©dur=n
her=
¢|l_lneaw_
aa
I_er_ _ho_ Oh0 ua©£t_lne=§ of
nenn©;
noise
_hQ Lntarnctton
pnrem¢_rl.
l_ orient©d
_o_rda
ind_ntr|nl
barrier
to
itn
Application
to
=_dtal¢o
In
_he commonly ,nnceady
hn= the
p_od,c_Lon
p©rfo_rrmnc=
or
l_
of
the
engine
_t
the
tndeptndent
lntek=
Lwo-cyc|a
eyp_|
nny internal
cn_nbLlity
to r©v¢_
diatnnce
And ©_hau=t
_torcycl©_
m_|_lera
o,¢bonrd_
Lh©r_ |a no _heof:etLc_l
comhultLon
enRlna which
lnhall_
or
ran,net.
Acknowledgement a
The author
like
Lo ncknowlcdgn
• t The _tleoul_
Univereity
prosr=m
and who cnrri©d
_f
I
would
ferLea
th=L¢
theoretical
Pc,
_,
_,
(at
Mercury
Coac©a
o[
Belfn=t who
HarJne)
H_ccury
eEforta
leLd t|m
ot=t the =_p©rir_=ntal
premL_oa;
(nt
the
Pc. J.
H_r/ne)
and Dr', H.
A, 5pechko
on the
C0 A_h_
(nt
459
noine
I_ohlec)
of pn=t r==e_rch
_cotmdhaH
work
for
chi_ ¢omp_tter
to veri_y
(_¢ _arner
Jtudenta
th_ _ccurncy
f.l©ctr_C)_
proEr_m_ I _c,
1t. L. Cahoon
on Lha ensLn¢ K_" flow
at.dLeno
i
11!i : "' '/••:'
_b
_,_ _.ll_"_t_,
+.
'll.i I
I I--I>l_l
l_
_li#l
*_ll.
leall
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).T:
0.751_
)-a(
:_I
'1
LO00
,
5000
1
,,"
/
engine
\%
...
7000
1
°.<%
-%\.'+%
--,
60DO
speed - rev.Irnirt
t
_"_ /
_Io_8_)_
=.
\_
°V_J/ _'÷\
8
•
20 _
30 09q +
"-.
I
•
FIQ. 2_
8000
-
_rall
75
//
""..._
÷
noise
a,.
d
"I_
fl
?(
intake
noise
65
60
mike al 150m
sooo
'
eobo -
,
8obo
Fiq_3:..
462
, i .
,',.
7obo
engine speed rev/min.
,
65
I ,)
7O
overoll noise
65
6O
55
Inloke
noise
exhousl noise
50
/,5
;'
0
35
engine speed : 7000 rev.lmin
mikeal 15.0
m.
30
I
,
•
,
,
A
1
!
,
5
,
,
j
_ ,
10
HarmOnics
,IG_4
--
i
I
,
, _' %' '7
,
15
"7
17
F_i9_.5.:
HICI{OPIIONE FOSITIOHS
IiPATIII
HPATllE
(a)
0.25
O.75
10_1.6
(b)
0.5
1.0
(c)
1.0
(d)
(©)
([)
INTAKE dDA
EXIIAUST(ilia
OVERALLNOI_;E dBA
101.1
109.3
102.6
90.6
104.1
1.5
96.6
95.1
90.9
2,0
2,5
90,6
90.6
93.6
2.5
"1.5
79.1
01,1
03.2
73.1
75.1
77.2
15.O
15,O
FIG, 6 - HICROIqlOHI'. HI,ACED NEAIU_,R TO
INTAYd_. SOURCE
BICROPIIONE POSITIONS
,'
•"
RPATIIX
RFAT]_
I_TAK_ dl|A
(a)
0,75
0.25
99.1
110,6
110.9
(b)
1.0
0,5
96.6
106.6
105.3
(c)
1.5
1.0
93.1
95.6
99.7
(d)
2.5
2.0
58.6
92.6
94.1
(e)
7,5
7,5
79.1
81.1
B3.2
73.1
75.1
77.2
(f)
15.0
15.0
E_iAOST dBA
OV_,P_LI.NOISF. dBA
FIG. 7 - HICROPIIONil pLACED HEARER TO EXIIAUST ,_O|)RCK
465
,
h ,
. d.
O5
i
_ _
..______A_'_
"°-_.
_---',
_
r l/v ....
_/
6.:
o/-
_o 6
i
--
-
_1'6'
!
!
_i_LI
•
J
.c
'
1LBsilencer
ou|l_.t
._o
tube
diameters
,
_
2'2
DDI
-DO2R,
mm
_
0'75
9O
intake box2 - LIN
80
.!ntokenoise levels- dLIN
("_tandard'}Box 1
BI.7
Box 2 _89'4
dBo.
79'1
"79.7
'ntoke
/\
I
70
_
I
AWT
6Ot-
f
,,'
/.,..j/intake
J
B_ 1-AWT
mike at ?.Sin
engine speed 7000 rev,/rnln.
50
Frequency. Hz
}
Harmonics
11
t
I
168
I
• i
Fin 1N
^PP_NI)
IX
Rcpor_ IIo,I0_)6c}_ Tim Qu©Qil_n Unlv_rnl_y
of [lelf_u¢
on a ComplltQr
of
Pnr_orr_nc©
Prol_r_m
(or
tim Prcdic_Lon
Chnr_cCar_nl:Ica o{ n Two-Cyclv F,
np,J+nQ
b7
Profanmor
!
L
I
I
I
r .
! .
_loLa© nnd
G.
P, B|a£r
I-
"1
A Compu_©r Pro_rnm for ttl_
Predic=Lon of Noise antiPerformance
Ch_raccarLi_Ica of _ Two-Cycle EnsAn©
by
_rofo_oor
R©por_
C. P. nI_Lr
No. I096
L.
.J
Summery
T_Ln report:
conl:alnl
us_
of
a computer
the
performance
; •
combined
"
da_e
la
of the
/_lQut
noise
noLee
called
e_:c.,
spectra
levals.
if|eluded,
as backaro_md
program
charncq:arisr:ica
conmttmpt:lo_ t air
.ql]d o_aulll:
n daecrlpt:lon
aa la
material
of
power,
an well
and |:heir
t'afar_ncu
aa
corqu_,
overall
dnncrlptlon
_t©rini
and Am ©xperlmen_al
int:_tke
proof
_he
and
Inpu_
furl:lint
arid output
atudy
and
of t_h_ accuracy
predlctlon pmrhod.
47u
__.a
for
ghe
fuel
_eparaCe
of
for
predLct:n
Lh_ _p_rn_,-
Ashby Ins|trots, Stranmillla Flood, f3elfeGt 8T9 5AH
,
nhee_a
"TIlROUOIIFI.O_' which
of
A br|.ef
t:ho dat:Jt
Telephone,40_3_L
66111i
Telex 74487
BTIIROU_IIPI,OI#J " ,I etl!!ljlut.or pr,,_rarq to
gad no[_. e!!,!r,lcteriatLCa
(If := c[';mkcaue
c_vc lven_ine
ibrL.dict ill(!
.cgraprel_i,m
R_n_arcll
of
19D4
to
the
flow
behaviot_r
of
or
apark
lgn|tiot_
or
rotary
pinion
lllnir
(3)
from
of
to
ch_lr
8iw
at
,
two and
natur_illy
the period
th_
unsteady
four-_troke
arq)lrated_
,llld Cahoon
work
chroush
by I)lalr
8 fine-borne
nulno
cycle.
with
haft
(l).
r_oved wi_:h
8no
Dle_et
r_ciproctltia8
el|i;ille
co direct
power,
torque
nolae
(6J
evaluation
anti
(5)
the
of
the
the
ayatcm¢
pr©d/egion
intake
and
fuel
dcacrlbed
pipe
tim ntlove-_vl_tioned
(2)
prusre_alna
and apeeiflc
I)y pulaating
created
for
and Anhe
a naturid
of
and Contea
with
Blair
the
character/at/ca
whicll
th© naturally
ignition
be handl©,l_
and
dine
and
valve,
eycla
th£a
©ngtn_.a
vnrintior==nf
to|' t|zn
acvernl
and
computer
and exhnuet
tlcta_l
tile
hurnins,
ayetema
Intake
of
geom,:it/ca1
crnnkeaa=
can be nnMyacd
which
typ©=
eompr=aMon_
with
thin
nnd cM_aunt =yater_= which
uyntem
Induration
_l_ch aa pinion,
emltrol.
typen of ©ng_,ne handled
¢_h_l_t
(b)
noa-_xhau=t
(e)
tim _ln-betwe_n'
nlgnntur_:
acction
Raaol/ne
newrnl
in)
The
follow
aapirat©d_
two-atrak_
Ther© or=
Ti=¢ _dn
(a)
reaearch
work
Ih_©ta
data
program.
.
over
co;,_hle, d eft©eL,
d=tnil=
rend
or
no_, be©it incorporated
The
can
cnBlne_
charactcriati_
evaLuatLn
haa
l)elfa_t
l_l_Iud lit underatlnldi_qi
by Blair
8an flow
Rclti_ed
of
of
pubtiahed
purfarman¢¢
program
typv_
Univurt_ity
_QCIliKIli_X[I_.
pretilctloa
rr_thod
.park
nil
hzla beell
auperchllrsed
work
eonaumption.
or
day
ahowa how thin
¢nfil,lu'a
Lhln
a_ Thu (l_eun_t_
prcn(_nt
Race|It
;
work
perfnrt,al}ce
t_,o-:_troke
fulled
of
(_ocorcyelea
unitn
tuned
tll_
aru
enstnen
tmltn
proar_ma
(lnduatrinln,
or
part
=nhauat
applying
mainly
are_-
J_
.C.P_2
and nno_q_ohllea)
and
GP_6.
472
chnlllsawa,
tuned
to
lnw|_mowur=)
(outlmard=)
trait=
typified
in
Tile ailinature
o[
tilt'
[)ro_lrnm,_ nlH)lyin,:
fnllinly
to
unit_
typified
in
(b)
nnd
Co) arclGPIH,
Tim middle
lndncLion
Hlddlo
Lniti_l
proc_,
P rufern
to
with
data
R and l) refer
lnitial_
c[lnrLtct_rinticB.
In
ind._trial
ensine
with
data
later)
_nd
olleot
tim
othut
GPII3 lllld GPII5
the
prosrnln
oriented
°diace
word_
I Illl
illustrate
a "pi_ton-portcd"
_cqnence
to
exhaust
prafrtlrrnCl|lll
and
and
that
_u_d "disc--valve"
proE_rilca GPB[ refcru
a uinlllo
suit
to
a _/nsle
GI}Iil would
pro_rmn,
induction
11 pioLon-ported
intake
hoK oiluncer
clllculnte
the
(as©
altcrnate
lot thu oalmt__y_tCOl_ bug for Irc_d °
units.
valvud
Tll_ numeric
thQ ©nflllll
in
to arced-valve"
nola© and perform_nca charncteristic_
_nd
inde_in_
symbol
1 - 6 d_in_
apart
type
of
n =InBle "llo?i and
tlnl_HI havlnB
thll,
t_
from ©xamin|.n8
tile
exhaust
_y_tem
tlll}fl II lntakQ
nketchos
in
attached
silencer.
tile
To
aheata
data
to
_hich
follow _roar_m
CP_I
has n _ln&ln
bo_/t_b_
r_osram
CtHI2
has _ s_r
Pro&ram
CP_3
has two box/tabs
Program
CP_
hat
o_ foyer hox/tuh_
Prosram
_lluncur,
exhaust
witlloU=
allnnecrn,
two box/tuba silk, nears
a tilncd oxh_lllt
i
exhan_t
with
without
a tuned
exhaust
all©ncers,
t_lth
_ tuned
a ¢llned
©xhnunt
_y_tem.
on_ t,b©
p=rforated,
and without
system,
GFI_6 ham _ =In&l,= perforat©d
tnhc
silencer
and a tuned exhaust
pipe
system.
_lm
for
_ollowlng
pal{a,
PIB.A,
pro&cam CpBi - a p|.ston-port©d
i_
a reproduction
induction
o_ nn act_sal comp.tar
un_,t o actonlly
Tha first h_If oI the °u,_tput_ from th_ proar_m is th_
I
specified
listed
in
of
th_
n_#tp,_t
ch_ln_aw
"i_pnt n d_a
type.
aa
that
in |ha
section.
data =h_ntu
In otlmr
whichwords
followfrom
and _911P.
in the
to ^TOY
exact (cylind_r
ordar of bor=.
t|m data
rn
to air to _1*el rmtlo) ia-th_ data li_tJn& £nr tlm anRinn,
472
Th_ unita are m_trlc
,<I _ _r
• ,,
.
(Ill)
Jill
lad linear
ilil_nlllollu
Jlre tr_% with exhauflt tuznpurnture (TWAI,) lieLud
OC,
_lla
_I_|L
mix
with
tllii
•p,_llic
n©cond
hillf
of
O[
_he
C_/C_QO
_tltll
fli©l
lllld
6he
output
(]n_llle
ntiltli
renult
oll
the
el:c.,
_[_ectl'u01
o[
_t
the
cliicillationu
ao
not
for
iilpuC
wllue
of
iilhl_li
/Ire
i:or
/or
'paper
Ii
pl'hlLed
Lhe
owrnll
of
coni]ltltm_r
ciilcu|lltlono
li_l,'C,
lhe .611© cnic.ln_ton_,
the
rullll_ll_
cycle
cono_mptlon
i_
engine',
IIIIP I
llow_r
_ilBln_
tim
prc_llur_-cL.inikolllll_L
_lrAphplol:L=r
for
tillB[_
the
hint
ptcLui_tl
(llixCli)
cycI_
life
alan
drawn
calcll|nLioll_
eee
liliUrli.
_hli
itl'ltl
con_tnl
OU¢l_lil
_7mbol_
dl!l[llCll
engine.pe_d_nv/_in (nl.o
or
gSBCI
lll|)lii:
bA_ed on hrnkQ horaepow_r
IG#
klinwnLi:n _ kW
KC
lb/hp
-
itllL_,
willil_)
(746W)
J_llll cnnilllmpCJon nn
¢p©_lJ_lC
L_
_i_Pl
nn
_IIP -
brake
or
b_lnwi
h_
ks/kW h
brak_ mean _f_ec_ivo
prc_nurn
_n
i
l
or
IH_PI
P61 -
Iblln2
KPA -
kPn
indlenrml
Pfll
or
i
;
P_R_EPI
KPA -
_
"Jr ,;
KPA -
/lfl
kPa
IPt_in8
-
_rrlfillllrl
Ibl_,n
2
crankc_ae
PSI
'
-
_enn e,,_lr,e_lw
lh/ill
mean
e.ff¢c_ivn
prnnaur©
2
kP_
47_
I_a
lly
la_t(lllxtli)
Filbll
Lhc
,
lit'like
_ipc_¢l_
cycle only,
_hQ
Lho
c_li_lliiL_l
and
nil
IIPM.
FHEP=
frictfou
or
BKt
tilt!an efft!cLive
PSI
-
lb/in
KPA
- kPa
delJ.very
i,re!;f_urc
at;
2
ratio
de[ined
au
mann air flow
lmiuced
per c__cle
meat| o! enl_ine'a
_wepL volu,le
at
' wlmre
5TP ia
"_tandord
(760
retail8 or
101.326
(_
charfiin
temperature
8 e£f_eieuey
trappin_
defined
©ffizlcucy
5El
_eawn_ln8
lmr
u_flcicncy
(Alto
P_RAPl
PP,_L;
can b_
crappluB
prenfltl¢_,
tmtcn
nttn.
of
foliate
pr_a0tit_
D or
_lno
_¢AVt
,_CAVI)_
t:he, nun_ber
traneter
port
last
for
tht
fitnt
to
distance
or overall
_n inpuL
=co|ion
(_lxth)
th=
tit= nth
in|akin
(RPATIll
noite
n_
charge
pre_nure
at
I
I)
pol_
e_hauar,
during
Vtlltt_ t _:_lmtt_t
of
port
opening.
Fore
tl_nln
calculation.
harmonic
nyat©m
and
combuntion
temperature.
d_fireeu
of
¢loaure
in
opcBln_
in
with
the
.ol.e
o.tput
part
tip _o it mar.lrnmn of
an_ RPATI(_.) [rom the
_pe¢cr¢%
Lh_ combined
eahattoL
ayntcm
'mic:rophono'.
noise
apc_tra
o[
Incavenging
e_platlatlOl|
Tim f_rat
th_
tt_ utlitn
arm,
°C.
'p_rft_c_
[ull©r
474
i i I
purity
ne exhttunt
prenauro
p_efi_ttre
o[ output
cycl_ of
to
cycle
|trapped
or
_A[,I
applied
_i,i'i:_
• ,,-',.,
an
_n_Lml_n cylinder
the
aa
per eyt:lo
p"-'-_r
cy_c ¢_-"
PHAKt
7he ne_C
fiTP
o[ It_.n.
tmtta
l
teen
at
defined
maaa of air
trapped
_ot_a[ '_amn t:rapi_Qd
and pre_uure
au
defined
renan o[ air
tra__
_anh o_ air imhiced
(20o¢)
kPa)"
r,lasa of air
trapj)ed
per cycle
foa.t= o[ enaine'a
awept
vbhJm_
_;
S'H'
nhow.
frcque.ncy
a_ their
after
_=n rllferene_
imltly_ed
th_
o[
(2),
over
nolo*:
2000
_pcetru_
I1_
re_p_eLlva
hlno allom_ i= the
o[ I_h_ tntak_hnt|
to_l
_ah_ttat:.
t
_y=tcm.
The wdueu
level
in
in
d_)
Ln dB nnd ore
or ,a A_£
(welgh_ed
nnalyncd
liiw
Tile
[I
total
of
tile
output
intake
noine
mid cho colabin_d
6raph,_cal
for
Jeta,
_eC
line
the
*_nl! A_T),
[.IN
,ccording
Lo the
8how_ the
,unlnat_on
outpu_
r©nGo[l_ of
At` tllc
(hit/
and
noLne for
in
FL8._
^l;r),
both
(overnll
._ound preueuru
A-weighting
(l,O
_Q_ I_1
.t
ucale
facLor_
tile
bottom
360 ° cr=nknhn(t
of)
of
IC (inlet
cloaing),
total
of
rhone
exhaunL
nource_
npcctra
tloJ_e
(LIN
(L1H and AHT).
pre_ure-tim_
hinto;*lea
fll"c LIiQ crg*llkCtl_*_ llltd inlet
line
of
the
where
lLnea
and
picture
I:ran_er
duct
pitt.re,
_DC at
to top-dend-eantra
nnd
the
hainG ntr_nphertc
The x-_x[n
v=rticnl
all
in
two
port
heln_i zttmoepll©ric
pl_cloll_'cn
prca_ure
arm,).
llna
The
notue
o[
C[dltILy,
top O_ tho [)_c_uro
(a, tddle
r=fer
the
ahown thll
(J,|l
Arm.) W_Lf:|| Lho horizontal
poc_
drawn
openin_
nee
the
prc=nurea
cylinder,
(ill
run
TDC co TDC (on
from
tile
centre,
gO _nd _.C (exhnunc
diasram;
cloninG)
port
of
from
, TO and
475
the
piston
npnrt
opening
with
the
port
nnd the
horltontnL
=trn.).
nnd bottont-dend-centr©
end
ntm.)
(1.0
lflO ° la
oll tht_
czh.uat
pr=a.uro
<
"
,n
dl}A).
The last
to
urc
tile
cycle)
or
picture.
TDC nnll flDC
imnlt/onn
r=npectlvely.
TDC,
TC (trtmnfer
nnd
ninth
cloninG).
fll)C nnd TI)C are
pore
IO
opnnin B nnd
No._mlrnOh
*_o.
OOw_
pONT
|r,Lklr
Punt
TflAhOFCtf
£_/,
Tt/_Pr,
OATA
u
Lt_t'ht)
DATA
& OAIA
Irl1|cr|or_
_1_[
DATA
uuGT
t_rIGlI,E
*.;D
•
I,HT,
,O,q
E_tP*
IIUX
._,_
EXr_AUbl
b_,LE_LLh
I.L,.I
t. _,,,
Ero, l_Irlr_/*x
fill _
t_u+_r_ttI_AFI
t._
K)A h
_d_,_t}
OA;_
FF
.,0_*I
FtA
,J._q
/)A_ri
nl_ |It
H'
FF
ml. *JJ*J
v:_
.32t(
a:_tl
_,elk)4
FFO
_ArOA_IS?
r_
t_rl_._
KP
p,
_
_
nT.P
OtJHr_G
ATII_
Phi
I_ ;_pt_t_
_PA
r,I A
UH
CL
T_[
ill
k _
[.,tA,JOT
(Ill
tiir
,o
A_I.
lille
*l
'"°i'"
MIt.
**Dr1
r_lt¢Ai _ P_.t.
|.J
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13.
A'_|
i_!
i
g_.
AHT
O"
.r_,5
ti.tJ[
•
TO:_!
_,_ ,
pL_T_Urt
J*
_-nAI
_ic.I
|,_Ai.
gC_,V
4;_U*
_***
I_AS.
bCA¥
Uf$
t
M)I;_
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_.,x_
l_J*
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rl
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r'n_
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I
!
RI_]:I_RENCISS
1.
2.
G.P.
l)la/r
al_d
W.
Gn.
F.nBLne"j
SAI.' TranthlctLon_
0.
P.
IDnLC
Flaw
V_htclm
and
O,
P.
ThrouGh
H,
Heating,
]llnlr,
"l'rcdLctlon
S^g
76064_
C,, I%
nXalr
and
S.
_fXux
Tr.naactton_
Vo1.82,
5.
and
Coat©a
Char_ct_rlatlca
,_A_ FCIH
I
i
•
i
,.
n_
Heeting,
P.
Blnir,
Inter.al
H[lwauken,
Vehiclo
_^F
_cllange
?GO6l, lh
Performance
HeetinS,
Prod.cad
ComhliptLon
tlilwllukee.
by
UnatQndy
f:nEinn",
SAF.
730160.
"F.rthQr
.gt.dl©a
Comb.atlon
._npt.
47tI
i
SAK
F,nslno
"H_lLae
Internal
1'.)73,
?..
Two-Cycle
Ga_
_qAl_ Off-111ghwny
1976,
Sept.
of
SAV. 720156.
I_n/ILne",
Coatea,
an
from
AnalyuhJ
Two-C?cle
Uas_em[y
Of£-Iltghvl_y
hr.
Colnplete
19720
"The
of
1976,
!4,
Vo1,01_
Aoho,
5AE
Hore
n llLl;h-SpecLfLc-Output
Hllwauke¢.
_¢pl:,
gxltallmt
5.
C.
"^
or" a Two-Cycle
Chnrnctart_tLen",
4.
Cahoan,
Sn,teady
Chnracter[,tic,
3.
L,
Enslne
lgZtJ,
of
Noime
l':aha.at
,_^K 74071J.
,Sy_t©ma",
D;IL;t Shu(_t
/0[' HThrouJ_hf|ot]t*
" .1 COllljl|eLt_
fL(_;IvIJIll;{tliI
_ttdtJct_nll
RIId c_hatutL
anaIyula
of
it cl'_ttd_cll_
._
con;l)ren_oll
two-a_roke
_ycle
t'n_lne.
J
G.
l'rofeauor
P.
lllair
gHGIffE NANE
E[IGI/_,_ TYPE
NO.
OF CYLIHIIERS
IIII)UCI'[ON
,qY,qTl!H:
(a) l'i_to_l
purLvd
(b) I)lac Vatvu
(c) Reed Valve
_J.me,
nnJ.on
:
Symbol
1.
Cyl_nd©L"IIoraj director
2.
CylLnder I;_roke,
3.
Conn_ct_nl_ rod e©n_reB,
4.
Cr_nknhafL speed
1_1,_1
ltev/rnin
5.
_h_ua_
_(ll_)l'_tl
dosr_Qa
6.
T_n_fe.r por_ _lr_n_
d_Rree_ ^TI)_
TIt^_OP_
d_reem
7.
Inle_ por_ 0p©nln_,
_I_OP_,_
_le6r_©a
8.
CylLndnr Lr_pped cor_pr_nalon
9.
Cr_lkcan_ 8eomotric car_pr_aion
tnt|n,
_ncludln8 tr_nnf©r duc_
C_IAHt(CR
O_ Crankcase
_
_ncl.d[n_
C_6HKCVOI,
part
DORF:
len6th
lenKth
_lm_nAi at: opcnil_,
a_ opening,
del_r©©n _TDC
rn_lo
,%TROK£
_mt
CRI,
_
T_AI'CI_
cle_ra_cc: vohtm_
voh_n_ uf _11
/
TABLE I
Bee F_l_n°l and 2, for
fl_rth_r
479
,/.•
:
Ulzi.La
d_tn[ln
Cm3
I}aCa V_lun
/volume
F18._
Crnnk_hnf_
pOll_tiOl_,
TI_I'CK
p_lt.ion
trapped
_hown at e_h_lun_ clonlnB
pmiiL_.onj
th_ tr,pl_Ln_i
l_atJn|ly [:_ll_Ol'lr.ll d_i_ IITItC.
_
VOI,UH]; TI_AITI_D
CllANt}_:P,HLTII ['IBTON _Lt TI)C
ANKCVOL, cm ._
111
:_
FL_,2
Cv_nk_h_Lt
the
p_,tioll
Jhown
crnnkcnne
cle_ntzc_
volt_e pot
_ylLnd_',
_
bo_t_
voh_mc.
dcnd
_',.nu_a_
c©Dtzm,
_n
C_ _.
Cm3 Lhen ,'iV _, CIIANKCVOL
480
".
.}
,'
i
i i
ILI).C,
_
-
5V
I.I
nut_
th_
_t).l
_we_t
.q,.
l_lK.3
Plan
pcctl()n
cn cxhliii._t
porLn
_u_ exhnu_L
Fort
tt
-_
FIll.4 gh_w_r:Ion
on
/_
I) [lll_llll Poll
15.
r_uiidl_,r oI- tralmi'cr
1ft.
T0t_|
e[PectLve
Width
(_inually
OR
--
16a.
PorL
IHII'L_I
[in[ t zl
D_tll
TILgtlSl'liTl||l)
r_n
(_)
(b)
(c)
a
b
c
alLI31eU
0A
daBreaa
0U
dc/_r©ca
0_,,
daBraeo
n.n
ltln
t_
.
,,
17. Corner rndLu= on upper
o_ tranalot
port
odB©
TRTI_I}
r_n
)._.
edit©
TRIIRAD
r_n
COZ'IIOF rndl, ua on
O_ tL'nllll_llr
port
T_SF_R
X'ORT
?LA.6
POR?
lower
Vnlu_B
1'l_Ari._l,r4o
tr_tnnfur
port
2(_ + b + c))
HIIITll
R|I)TII
W[DTII
elevation
_iymho I
ELgVATIOt[
Pla,_
_©ctLon
through
tcAnafnr
port=
/_CL_
,_L._
I'h_,6 _=ctlon;
_lllvnt[ofl_
OAp
port
typ_
A
dQg
Oc,
port
typ_
C
d_R
4_2throl,gh
port
A_ J_, or
C.
i
I
TAIII,li 4
I)iln_ll_
IGll
_ylEillo
I
IlilL t _
II_lL_l
V_ hl_'J
19. lllll_liur
DE [lll_t
[ior_B
_O. Illtlxil_lil C[[l_Cl.[v_
cllcll Lnl_t por_
1_II1'_10
EIII31iTlt|I1
lllli
;_1° cornar r_ldLll_ on _Oll _dtJ_ u_
_li
I.nict I_ort
I!_ITII^I)
irln
22.
1_111111^1)
i_n
EIII'IITIIT_IA;_
_l_
Illl'
li_
corner r_d|u_
o_ _nd llll©t
width
of
oll boLlonl edll_
i:ort
2Jo l_xL_llm poa_llJle
h©LIIllt
Inlet
24.
¢l[bur©t_or
_ll_a_r
2§.
in|©¢ por_ liol_l iIr_ll_lliL _nll[_
wrl_ cyl_n_l©r ccnt_-lill_
IllilVltllll^l_T
26,
l©nStll
LG
nl_
27,
|_lll_h
1,7
_l_
i_lillliill
_l'o_l
flow
i_l_Lon
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PAIIELDISCUSSION
ThursdayAfternoon- October13, 1977
The panel discussfon was conducted in two parts as follow,s:
Part I: Panelmemberswore asked to discussspecific
issuespresented to them.
'
Panel
rlembers
:
l;r. I1. J. Alfrodsnn - Honesh Untv., Australia
L)wightI))aser - General HeLots Tocb. Center
Up. A. _r_mer - tl_t'l Research Council, Canada
Peter Chnn9- StemcoMf9. Co.
Prof. P.O.A.L. Uavtns - Univ. of SouthnmpCon
Larry Erikkson - liaison Industries Inc.
Uou9 flowley - Danaldson Co.
Dr. /_ndy
Seyhnrt - Univ, of Kentucffy
CecilSparks - Southwest _esuarc|l
Instit,
P&rt II:
EPArepresentatives from tbn office of noise
centre] _nd _batemnnt _nd from enforcement,
anskmrmlquestions fro_ the flnor
EPAPersonnel
Dr. Hllliam Roper - branch Chief, UI_AC
Scott l_dllards
- OffAC
Charles rbiloy
- ONAC
John Tho_s
- OffAC
Jim Kerr
- Enforcement
Vie Petrolottl - £nforcement
n
I
497
PART I - PANELDISCUSS]O;]
Ernie Oddo
Forthe pasttwo andhalfdayswe'velistenedto expertsin Industry
andunlvcrsltles
tellus abouttheirworkon variousmethodoloqles
beingstodled,developedandemployedto predicttileperformance
of mufflerson varioussurfacetransportation
vehicles.I believe
It'sfairto say thatfROStof thisworkhas beendone to aid in the
designofeffectlvemltfflers,
All of us present,at thlas)_nposlum
I an1sure,have a real appreciation
for theeomplexltJes
Involved
indealin9with thesignificantparar_terswhich
must be considered
In an)'Inufflcr
performance
prediction
technique.IIearlng
in mind
thQse complexities then, we would like to address tile objectives
of the EPAmufflerlabelln9contractandthe specificareas inwhich
we needassistance
frompanelmembersandfnmnbers
of theandience.
To o_n .thesediscussions I'dlike to call uponhr.0tll hoper from
the EPAOffice of flolse Abatementand Control whowill elaborate
on theseobJectivea,
Dr._
BI)I ,Roper
I wnuld.liketo go backand readover thefourobjectives
that I
mentionedIn m.yopening statement to rids meettn,qwhich outllnes the
specificobjectives
of the EPAgenera]labelingprogram,
whichI think
is very applicable here thts afternoon _nd appllcab]e
to thts entire
s_poalum, The firabeb.lecbfve Is the provision for accurateand
understandableinformation
to be provided to product purchasers
end
users regardln9 the acoustical perfomanco of designated prodncts
so that _ nmenlngful comparisoncould be madeconcerntn9 the, acoustical
performance
of the productas'pertof thepurchaser's
use de¢ialon.
m
m
N
This ob,iectlve I think, is a partlcularl)'
fmporbantone with regard
tn the _ubJectof th[_symposium, The secondobjectiveis to provide
accurate aad understandable
Inforlnat|on
performance to consumers wltil minimal
third objective
on product noise endsston
federal
involvement.
Tim
Is the promotion of public a_larenoss and understanding
of eevIronrF_ntal
noise and associated terms and concept. And tile
fourthobjective Is the encouragL_11eet
of effectivevoluntarynoise
reduction
aed noise labeling
efforts
on tile part of product manu-
facturers and suppliers, filthtbat quick review of the principal
objectives of tile £PA general labeling program I would like to go
back and focus on objective
with InforBatlon
acoustical
one which dea]t
tilth
providing
at tile point of purchase-decisiorl
performance of a product.
relative
No,J, that doesn't
meanthat a product would have to be quote "physically
the consumer
to tile
necessarily
labeled".
Informationcould be providedto the consumer In a number of different
w_ys, It In essentialto provide him with Infor_tlon on the acoustical
performance of e product at the time he makes the p_rchase decision.
He think thls Is an Importantconcept. As consumersutilized the
acoustical
information
such selective
in their purchase_lecJston
decisions
used In thiscountry.
will
it
is felt
that
have an impact on tile nolseiness
It's.away
of
potentially
(letting
oF prnducts
noise reduction
resolvedwithoutany requiredfederal regulatorystandards on the
_nufecturer of new prodoctsor aftormarket part replacementmanufacturers, in 1ookin9 at the problem from the Aspect of a Voluntary
standsrdD consider
can rake a voluntary
that
the consumer, given the right
decision
Information,
on whether they want to buy a noisy
product or a quieter product, _Iithoutthe acoustlcalperformance
Informationheaever,he really can_h make.thab decision. In a
goners) sense, thetJs one of the principal
reasons that [PA 1_ interested
In labeling vehicle exhaust systemsand is collecttn9
Informablonat
thIs tff_ for u_e as background data to evontoalIy
for decision making within
put Into e format
the agency.
I_d llketo lookback at whet I consider tileseparatepsrts of the
label.lag background shudy that wo_ld have to be developed In order
to havethe necessaryinformationto implementseth a program. One
deals with the technicalperfomance data relative to, In this case,
499
ll/WRIX
CateOorlo5of eng|nosvs, currentbestl_luffler
assesslnorlt
approaches
Huffler/L_ses
sment
Approach
Lt.
Truck
lien
vy /_utorioter- SnortTrt_ck
n_obl
le
OL#Sos
cycles
mobiles,. . ,
.
,
, ,,
J ,,,
,
('aranletrlc
Analysis
_cowstlcflodcilnu
Engine SlnJulatton
Standard Engine
Act_*al
En9 no
'
Other
!'i
*t
_}
f.
lira I
IIISTRUCTIOIIS
TO TIlE PAtIEL
Pleaseconsidertilefollo_.Iiog
t_loquestionsfor applicationacross
all surfacetransportation
vehlclesor to a loqlcalgrounJnqof these
vehlcles. (Light and heavy trucks, autos, busses, motorcycles,
sno_nobl los, motorboats)
Also considerapproachesthat:
I. Do not use the ellglne,
such as
A. "Parametric
approaches
B, Analyticaltechniques
C. Enginesimulation
2. Usu an engine,either
A, Standardengine
.B. Actualengine
_}EsT
lO!Js
I. Is therean e_Istlnqbench testmethodologythatcould he used
to testmufflers,which _¢ouldglve valuesthat:
A. Could be added to the.nolsecontrlbl_tlon
of other
predonllnnnt
sourceson a vehicle,to acc¢|ratel),
predictthe total vehiclenoise level,or
B. Wouldcharacterizethe performanceof a replacement
muffler,comparedto a vehicle'sOEfl
muffler.
2. If no%,can th_ panel make reco_|nondatlons
on themost promising
bench testcandidatesthat _euldl_n,
et the objectivesof q,estlon
one. and tilesta.ne
of dnvelopmnnl:
of theset_sts.
i
tile exhaust system; tile other deals with conmuotnatlnn of that
informationto the lay purchaser er user, I'd llke to separatethe
latter one from the discussion today and cnncentrateon the technical
perfomance aspect, A major part of that considerationis of course
the i_easurmnent
methodology procedurethrouqh_iblcll
yotlcan collect
the requireddata. Selection of n met odologymust be based on a
whole series of considerations. TIiereare many trade-oils. To name
a few there'stileaccuracy of the procedures,tilerepeatibilIty,the
simplicity,the cost involved In both th_ operation,and tileequipl_aent
instrumentation. These trade-offswill directlyimpact_Ahoever
is nsln9 the measurell_ent
procedures,as part of his design or production
process, For the post 3 days this synlposium
has focusedon one type
of n_easurement
methodology the bench testj to determinewhat was available,
problems tlat miglt be Involved In utllizingwhat is avnllableer more
basically, If such a measurementmethodologywas even available,
This methodology referred
to is the use of bencll testing
far determlnin(
exhaust system performance, I thin]:from a labelingstandpointt_e
w_uid be'looking at the muffler partlcolarly,altbouqh I recognize
that many, or perllnps all
of the people that have participated
in the
symposiumhave stressed the Importanceof lookln_]
At the total system,
I think frr_ a labelingstandpoint the most Importantpart of the
exhaustsystem Is the muffler, althongh you'd have to consider tile
total system In developing the Informationbase to properly Identlfy
or characterizethe muffler. I thlnk another element here is the fact
that in carryln9out this program, conductingthls s_iposlumand
Investlgatlngwhat procedures are Availablefor measuringexhaust system
noise we at [PA recognize that .tim industry and the people such as
yoursolmas_t_hohave done research In thls area over tileyears Are
the experts
in the field,
Yon are the ones tltat kno_¢what can and
can't be damn both froma theoreticaland a practicalstandpointand
He would llke to benefit from tle knowledge thatyou have and receive
recommendations from you based on the best Infonnatlonthat's
I_
_
available
on what you would recommend to CPA
AS far as any measurement methodology
for vehicle eKhaust syst_ns is concerned. /low, we get down to the real
502
•
,
_
,._
_'
'_;_':'i-'//'_/
_/_ L:
•_,::__!L" _
¸
-
:
,'_"
'
pretties{
aspect of tile
to look eL specific
Available
test
tusk we at EPA hove, to accomplish,
which is
exhaust systems end Lo determine tile most practical,
procedures to use, to obtain ropresentettve
acoustical
date. i hove broken out here on timevieilgr_ph
tile7 major categories
of"productsthatwe ore looking at at this time. I would like to focus
tileottentlonof ell
7 categories
those on the p_nel nod the audience on these
and based on the information
in tile last three days ! would like
and reports
that
we've Ilod
to chellen0e yet{ to come up with
your best recommehdation on how we might mensure end cheracterlze
muffler performenceon tilese7 categoriesof vehicles. _(ow,I recognize
thor noneof timeproscntatlon$llovespeciflcnllybroken the products
out thiswey
elthough
I tlllnk
there are possihtllttes#mere
for combining
cerCain cateqories. I would he very interested in the comments that
might come forth
on these particular
olleod end i_eflen
the liberty
of o general approuch to muffler
down the vorticel
assessment _nd listed
can we fill
out?
brenkomt
so,,eof those
Hhet's evollel)le
there ere two or three procedu_s
one category here, maybe w_ should talk
tl|oso
i#OltmI hove gone
_rtkkson's
_xls here and i guess the question conies down to #low
mucI) of thmt rr_trt_
perheps if
applications,
of using some of Lorry
throe ere l)est far
o_ we move into
And
_velloi,
le for te_tin!!
in
ghoul e ranking of which of
u_e in thor portlculer
that discosston,
today?
nppll_'ation.
I think
since yell ore the e_perts in tile field,
you Ion else interject
your concerns for tileelliot elen_nts of meesure.
ment metlmdolooy that hove to he considered at some point such as
simplicity,
cost,
_ccuracy end similar
things,
o time st_ndpolntc_lls for our controctor
to pull
tnoether
end present to us In opprnxlrr_tely
reco_nmendsttons from this
this
question.
make decisions
The rpA proornm, from
Mcl)onnell 0omgl_s Astronmutles
sympostnm, elonll with
These recern_endettons will
their
one month, the
own views on
be used l,y the EPA to
on o (lrneeduro or procedures to lie .sod tn our testing
program for neosurln9 exlleu_tsystem meffler performnncei o procedure
other then for m_surtng
will
totel vehicle
bencl_ test procedure we have selected,
I
sound level. O_,rcontrector
be condnctln9 tests using both betel
vehicle nnd whatever ether
starting
tile first
port
of
working under and the purpose and objectives of this sy_posium,
next year.
{ have briefly
su(_n_rizod t)_ progrem schedole that we're
Our grleary objectiveIn this s_nposiumIs to come up with the best
availabletest procedures to be used in assessinOa muffler exhaust
system porfon_nce, ether than by usinfltotal vehicle sound measureeent procedures, So with that challenge to tileaudience and the
panel I'd llke to t.rn the sessioo back over to Erole Oddo.
Ernte Oddo
I'd like to amllIify
on one of IH11's statements. Currently in our
contractwe are going to test vehicles In each one of these coteqories
that ere on the board, fiew111 also test, a mlnhTlmnof three aftermarketmufflers on each one o" these vehicles, using the currently
most applicable total vehicle noise Mensur|no procedure,such as
the SAE J-336 for trucks, for instance. Then we will take those
mufflersoff the vehicle end test thc_ll
using a"caadldate"bench test
methodology. This Is part of the test plan that Is In thecurrent
contract. Continuingthen with the panel dlscusslom I'd like to
flash on the board the questionsthat we gave to the panel at lunch
tln_ to revicw. We'11.glve the audience a chance to read the questions.
Then we wit1 flast|n viewgraphon tilescreen allowinga matrix of
tran._pertation
vnhlcles versus various muffler assessmentapproaches
we would llke consld_rmdby the panel.
Cecil
Sparks
Looks to me like It addresses It_elf to the evol,tlon of the bench
test facilitywhlchwill be used for actual pret!Icted
purposes|that
is to predict the sound level coming out of the thing which In essence
means t_ can then p,_ta label on this et_fflerthat,_111define the
muffler, the e_haust system, the engine, the whole thing, In'such
cases, it appears to me that your label's going to he bigger than
your muffler in the sense that If you consider all the possible
parametrlevariationsIr|volved
you're (leln9to hlcludein the lahe],
includingtiletesting facility,the wlde variations
end cngIne operating
conditions and the exhaust system,etc.. The approach Inferred
_I
then Is one of pred|ctJverather than Just a bench test facility
will have to be a label of the system rather than the muffler itself
thatwill say that this i_ a reasonablequality muffler and as such
and while thiskind of thing It seems to me Is theeretlcallypossible
_04
.b
lfl that you Call build
a source stl_allater
for any (jfvem nllglflc to
cover a _/tdo ran+jr of corrdltlons put Stnlulatcd exhaust systo,tsj
atE. on It,
the whicle.
Ernte
seeus like
It i/ould bo much sfl_lpler Just
to test
It on
Od,,Io
I itantto clarifyone point there, by lnbellm_wo don't ncccssorlly
mean physicallystlcklm9 n label on a nmfflor, llcilnve a AIoChbroader
dcscrlpt|on of labeling. LahelJe@could Im Just souc Idontlfyiflq
NumbcPSOll tile muffler stuilar
to tdlOt Is doric today.
Ttle eu_tbers
or l_tters would tdoutifythe nmnufocturcrof a mofflcr tdilchtilth
could be tr_ccd tack to the manufacturer's
catalo!h
•ost manufacturerscurrently Issue i+ould have all
The catalm_ i:hich
of the t(tformatlon
that yuu have discussed. TIHs is Just nee alteruattvc.
Cocll Sparks
The other _ltcreatlvc
would bc tu caterjorlzc
It
In tends of the
Inherent.passlvc responsecharacterlstlcsof that partlcmlar
cunflgurat|onbut agaln you would need th_ sameklnd of Infor0mtlon
_'re
talkln9 About If your lateralis merely to be Able to predict
what the ultimate
nolse
lev_l
at
a 91run ai)pllcat1_
than _my, okay this Is a ho_p|tnl
Itke that.
type (stAtionary)
w111 Im rather
muffler
or smmethln9
£rnle Oddo
As an eKample+ [ would llku tu rultcr_te that whlch Oou_ ffalleyfrom _onaldson
presented,
That approach is similar
to what _c ere talkiuq
for trucks,
In other words, DonAldson has all
cor_utcrlzed
on tab runs and In cmtalogs,
back pressure and a11 th_ other parameters
abmit,
kinds of lnfnrr_tlon
t4=lch take tnto nccoont
that wc discussed.
Their
progrmm con_Idcr_ the spcclflcparameters such as engine brock prossurfl,
ptpe length,
etc.,
and then Indicates
c_ndhlatemufflers,
for that
oppl Italian.
.
I
r
505
f_
s
Cec!!
' Sparks
Thatwas thepoint! was tryingtomake,do you do thiswitha bench
testfacliity
or do youuse theactualInstal!allen?
ErnlcOddo
Okay,mull that'sthequestionwe'reposinghereto the paneland to
the audience
today,considering
thebroaderdella!lionof benchtesting
whichcouldbe anyof theeatcgorles
up on tileboard.
Dr. Davies
I wontedtostopLackti<ostepsfirst- I knowlilil
Ropersoldthat
he wanted us to concentrate
on technical
performance
data and that
communication
of Information
concerned
was of secondaryimportance,
wellalreadywe'veseenyou can'tseparatethe t_lo,thc_'rea combin_I
©xcrclse.Youcan'treallydecideahou_thetechnical
porformnce
data you're_{oln9
to producewithouttakingtheconmunlcation
problem
with it soyou can'tdivorcethese. They'repertof the sameprocess
tn the first place, The secondpoint I'd like to makeis that when
yoncome.to a labellngprocedure
anti
we've heardthedlfflcultle.s
of
labelln9mufflerunitson theirolal
you reallymustlook at the.
system
andall theseothercomplications
andfiletthereisn't_ucha thing
as a woodor a l)ad
muffler,it Justdependsowl!low
you use it. The
consumerand if yo, think of tile
consumerin a simplelevel,and
that's the housew{foIn her house, she I{as the sameproblem, she has
to buy a cookerand o d|shklashef
and vnrlousotherthings,and operat
themeand oat themto performcertaintasks,shemoke.ma distinction,
she.knowswhatmile.
wants,and,_o! thinkthatid)ot
you'vereallyoot
to do is to thinkof the twotooetlmr,
you've,qotto providetechnical
information that's urlderstandable. It can lie con.:plleated, I moonyou
are.9olngto lookat thesalesfeatureon someof tills
mqulF,nent_
l
don'tunderstand
it. Timhouscwifc
does° Youdor)'t
get lmouedell
on thetechnical
prohl_s toe.
much,hutyou put tile
otherson the.
I
consumerto say, all duht we've 9lvnn you this lnfornmtion and it's
I
up to you to make proper use_ what he's got to be sure Is that the
information
isn't
dellberately
misleading,
and secondly the Information
Is surf|eVent
Judganent,
one part
lle11 now, that's
of tile problen, .. that
because It's
list,
qui_
I'm horrified
clear,
and I'd
lilly we've got recreational
cause o lot
I think
for
tllat's
of the problem,
by this
l|ke
tile second part
here table
to add another
vehicles
the first,
hirH to make a qualified
or _atrix,
category to the
there because they re.ally
of problems,
£rnIeOddo
They are not in our contract.
pr,
Oavles
They are not in year contract?
The second thing
[ dOlllt
oriented
tills
Then let's
exclude
these explicitly.
is that we have a very wIde range of engine types end
see how we can come to a simple and meaningful way, consumer
way of descrlbin!l
big"range,
tile characteristics
of
these systems over
For two reasons, the guy is not going to be interested
if it Isn't tailored to Ilia requirements,
Ile_s not_olnn
to go through
five pa9es of data Just to get the ttto lines he's interested In.
So what .you've got to do la to come up first
cla._slfication
system, It's not dlfPicglt,
you might put light
with
it's
a clearly
defined
here, heavy trucks,
trucks and autos together,buses are o special
problem because POSESAre operatedon tilewhale by corporations
tile corporations
have the technical
expertise
and
to make decistolF,.
And then yea*re got the other problem, tilesnnvm,obile, the motorboat,
the motorcyclep
ordinary driving
the semi-recreational
vehicle
and _lso yo.'vo
car and also our washer or nap
cooker
9eL the
or whatever
we have at home, in our house, I think we have to produce a different
labelingsystem to suit the applicationand I think if you start in
that direction
i
you might make soh_ progress.
507
'
Ernio Oddo
First of all _:odo tlavn
recreotionelvehicles in our contract,motorcycles and motorboatsare rncreationalbut on yoL_rpoint I agree with
overytling you sold ProfessorDavies, concerning this matrix, t_edon't
in any w_y intend formuffler labellng info,'mation
to be collected
in this fo_)at to he passed on to the consumer, lieJ.st present
this infor(natlon
in a matrix forn_t for the panel'sconsideration;
as on easyi_ay to keepIn front of you all the various possibilities
tl)atwe would like you to consider. I£orealize,of course, th,lt
for
light tracks one or moreassessnmentapproaches could be used. #:or
heavy trucks or automobiles,the same tl*lng
is,
can we flroup the eogine cat(tgorJes
holds true. The qucstloo
above a/Id then use one of
tileseparticular _pproachcsto handle two or three or four of these
vehicle categories?
Prof+ Davies
Hi)at! should l)_vebeenclear in saying is that I think that as troll
as this
catogorizntion
you really
ouqht to categortzo
the purchaser or whatever you'd ll_o
the fleet
to call
operator represents one category
sort of infnnpatlonthan the Individual
him,
the cons.r_r
That after
or
all
and he wants a differon@.
operator or tileprivate
individual. Yoomight think again that you really have a different
labeling procedure for these three categorles,because they Are
different.
£rnie Oddn
That's true and that'swhy we try to sepnr,_tethe two Issues - one
beln9 the technical, tiefeel that once we have good technical
infomatton
mittal
obtainml
from n good bench test
then of ti)ntdataor Info_tlon
problem, we recognize that.
methodology, the trans-
to the eonsnmer, I= another
I@oare also open for suggestions
on the
best way to transmltinformationto consnmers, but ! think the first
step has tO be.the
technlcal
question,do
i_ have a hench test
it wh_t we want to do?
methodology tilatwould give us good, valld, accuratedata to do Hfth
I
508
_T
• ,i '_
Prof.Daylos- It'sthisqoostlonor"accuracytilnt
bothersale,If
you'dleftout thatwordl'd go alan9wltbeverything
you soy. I
thinkyou i)ove
to definewhat youmoan by accurate.I ti)ink
It's
eat to be convlnclng,Convincing
is a differentovertone.The
consumer,thnguy tilat's
uoin9 to fit this to hiscarof tit thisto
his trucki_asto convincehlmselfthatwhat he doeshas ta comply
with regulatlons
and he needs information
thatwill convlacohim
thatwhat he (l_es
is a sensibleapproachto solvingtheproblemthat
he's up agslnst- regulatlons,That'swhat he wants. Accuracyreally
doesn'tcc_e intoit. lie's
goingto depend
provided by the _anufacturer.
on
tile
cerriflcatlon
£rnie Oddo
That'swheretlewant to apply theword accuracy,fretreallyto the
consumer,
we'rereallyinterested,
in themanufacturer
guaranteolng
that
his productwhenusedon a certainvehicleis ootn9 to do what lle
says it is 9oln9to do.
Dr. Brammer
I believethatthe sortof questiontheconsumeris probably9ofn9
to ask is something
verysimplesuchas, is thisreplacement
muffler
equal to tl_e
one I haveon my car or better,or is it worse,
and if
thesearethe typenf questlons
onewants to obtainanswersforthen
we're reallytalkin9abouta relativemeasureof mufflerperfnmance;
we're nottalkln9aboutAn absolutemeasureand in termsof qoe_tlons
thatare posedhere,thismovesus mare tnwordsn thanA perhapsand
also it enables us to,If we tl|tnk about It,_ can now start
runnin9someformof tes(:
as yet undefined,
in whlcl)
we can replace
single components,comparedwith the original e_lstln9 c_,nponentsm
and see theeffectof themr_lativato theorlginal_lft_ler. I think
we have to think a little
C_
m
bit about the type of labeling
thatwill be usedand the sort of questions thatwe
11
wnnt to answer otherw|se
on this
particular
usefully
pursue.
I don't
see heLl _le're ooing
problem but here's
to get
Zf one tries to answer qua;Lions of this
tt (lees get away from a lot
started
a notion that I thtnk I_e could
of these problt_ms of predictlnq
type but
the noise
of tilevehicle and thin_s like this and the accuracyof the measurenment
that was giving a lot of concern and rightfullyso.
If I had to ranh
order one A or IIof whicllI think Is most importantto the consumer
I think in terms of questlenshe's asking froma rep]acementpiece
of equipment, I'd rank tIabove A at thls point in time and let that
Influencetilechoice oF measureu_nt tecln|lque
that I tmuld Oo For.
Ernln Oddo
Any cerement
s?
pou.q Rowlet
IHII Roper laid dam
quite a stiff guhlellnefor us and I think I'd
Ilke to get them a llttle blt stiffer. Talk about thls accuracy thlng
and I'd "llketo ask, accuracy to do what? IIhatare _$nreally trving
to do?
flythat I mean what level are tYetryingto centrnl overall
truck noise too? Thee wo can talk _beut id_nteverthe e_haust system
has to do.
Can you comment on that
llIll?Can you folie_ the question.
In other words, _ome_lilere
along the llne I'm trying to get someone from
£PA to tell
me thnt
you'd ltke
to control
trucks once they get in ilse, to some level.
tile noise of the ne_slgT_l
Then, when a fellml
starts Iooklng for a rnplacne_nt product he'a got some flu de lines.
flt,ll
Roper
Okay, tn response to your last question,you're right, the netlmedium
heavy truck stondard_|sone that appiles to tiledate of manufacture
and vm have an In-_se stand,_rdfor Interstatemotor carriers1¢llich
ts 06 dPA for speed zones loss th_ll35 mph, there is a gap so to speak
in the Federal program although not in some state programs, I understand,
m
as to tim in-use level that would be applicableto tim medium and heavy
truck, say that's e_nufacturercdat 83 ,IDAlevel beglnn nq l January 7fl{
I
have under way rJqht nml o program at EPA doveleplogthe background
there is no Federal standardsother than the n6 dl)Apass by, nowwe
510
/
12
Information
that will
be necessary for
revising
the Interstate
motor-
carrier
regulation with the Intended purpose at this tfi;_e of setting
that interstate
motor carrier standard at a lower levol which would
be equiva1_nt foran In-usetruck to tilenelltrtlckstandards, in other
words a truck that Is manufacturedto meet an L13d_A ne_ly manufactured
standard would then be requiredIf operatedhy an Interstatecarrier
to meet s{_neequlvalentstandardwhile In use. flow,It may be tlmesame
,
level, It may be slightlydifferent because there'sa differentmeasurement e_thodologyInvolved, But ye_, we are addressing that nu_. In
regard to tho labelingaspect I think we're talkingabout more than
Just e label that Identif]esho_sclose or how a productcompliestilth
an existing standardbecauseIllsonm of the areas there may never
be Fcxlcralstandardsfor those products, ile'rea(Ininfocusingon the
Informationthatdescribesthe acoustlcal performanceof'that product
to the consumer so that he can consider noise as one of the elements
he thinks abm_t In making that purchasedecision, I gucs_ I would
also want to talk about t_o different
two different
labeling'.
types of Information
One would be If you're
ways that you could look at
that could be used for
comparing syst_l
a basis for
A _llth systr_l I1
or system A with the orlglnalequlpi_cnt,and that's such as .youwere
mentioning,a comparativetype of Information. The other would be
how does it co,parewith the total system or total vehlcle performaneo;
in other words, given thlse_ha.st system, how Is it (Iolngto affect
total vehicleacousticperfnr_ance. There's really t_iodifferent
approaches therefrom the [PA standpolnt;_:e
are not locked into either
approach. IIe'rolooking fur the one that r,_ikes
thefrostsense. There
may be implications,dependingon which kind of approachyo. tale as
to _that'savaliablefrc_1a measurement standpoint,
to provide the tool to develop tiledata for labeling. That's one
element that I'd like
to hear more co.neat on. Consideringthese
tv_ .qeneraltypesof approach,to collect the necessaryInformation
for laheling,nhlch one
has
the
necessarymeasurement tools com,_]ensurate
with It to provide the data, at this tlme?
_
51.l
Cecil Sparks
Youcould go a couple of waysin that regard, again ! think that if
y_u're trying to use a henchtest faclltty or evolve one wherebyyou
can predict what this purticular muffler will do on trucks X, Y and
Z, etc. you've got a pretty tough row to hoe. On the other hand if you
can evolve the system of lal)oling whereyou label tl_ truck and the
muffler that tills trick has, then, wimn a replac_entmuffler
is used,
class G31 and4X82 or somethinglike this then in essencequalify your
. mufflers for those various applications, ilow that I_ sc_thln9 that
seemsto n_.would be a practical approach. IIut ogatn, perhaps you dealt
neeto benchtest facility to do this you could qualify themuffler then
os i_ein9 original equil_ent or IJetter. And then you put in your nwer's
n_noal whtchmufflers you can use, as possibilities.
Ernie Oddo
That )rould lock it into 0EMonly and howwould th_ replacement
manufacturer, for instance, comply.
They'd J.st have to qualify their muffler for t_t
application.
Ernte Odds
Right, and that's what we're talking about, qualify it hc_?
cease!
Is_r k..)_
On thevehicle.
Ernie Oddo
Okay,that'strue,thstis definitely
one methndnlogy
thatcanbe
employedend we knowit wlllwork if you testeveryoneon thevehlcle,
but we ere looking for methodologiesother than vehicle testlng,to
_l
supply perfomance dat_ on mufflers.
_I
1/,
Cectl
Sparks
The point
Is thoughj
if
you build a bench test
facility
t/hereby you're
ahl,' to predict this mufflur°s
performance on this whole broad spectrum
of truck configurationsyou've got a ilorrermdous
Job.
Ernle Oddo
That may be the case.
Pete_.
r_ Cheng
I agree that whllc tilebest thing Is to put a muffler on w_achtruck
inodel. IIo'vegot two problclnahere. First, oven OCIltruchmanufacturers
cannot test tile mufflers on every truck model. Say one partlcalar
truck model, they may i)ave80 to 90dlfferent combinations, Some of
them have a fan clutch some of themhave differentfans, some of them
have transmissionboxes_ etc. As to tilesecond question, If
• we Are going Co test the muffh:r
on the truck who is going to do it?
Hho*s going to pick up the vehicle? There are so manyaftermarket
truck n_ffler manufacturers. Do each one of them /}avethe right to
ask OEMmanufacturers to testmufflerson every gnu of theOEM truck
mode1_?
ce_tl spa_
More people would have access to tlmtrucks t/_n theyt'Iould
have the
facility,I would think.
Peter thong
Hell, from our experience it's verydifficult to get a truck, Ileal
likely, we would like to test the muffler on the new truck because
the other
new,
no|so sources titre controlled
And usually,
when the truck'ls
relatively
the dealcr_ would not allow us to get the netl
truck to te_t and another tilingIs that talkie9with some of tileOEH
truck manufacturerswhen they want us to test s_e
truck, espcc|ally
en back pressure, they would speclf_,
the truck must have gross vehlcl_
weight. We have to put say, a fe_ thousandpounds at least on ti_e
{5
truck and no localdealer or l:hooverwould llke to loan us a truck
by putting a fo_ concrete blocks on It. I am lookingat this problem
fronttileotlleraftermarl:et
conlpaoles'
point of"v{cuo t;mare also In tile
OEi,Ibusinegs and first
of all,
our experience
again is 1 lmIted
heavy duty trucks, I don't knolvaoythio,j
go sno_nobiles,etc.
to
The
lleavyduty truck is dfffernt from the passengercar In one sense io
t ilA t
the custotIler
Is nloroknowledgabietbnn t{_ (lenera]consumer.
It Is a different type object. Second of all l am not saying that
they understandexactlywhat dl)AIs, etc. but at least overyon,_of
our distributorsll_sa no{so level n_ter they CallsonetlOyl
crank up
an angina and run some tests. And then. let me v{eo the problem from
OEMmarket experience. I don't think there Is IOO_ satisfactory
bench testme,bed, lIecauscof the pipe length,otc.j but the SAE
test procedurementionedby fir,Larry Erickson this morning, I think
thml;*sa 9god con_prnmise
bet_Yeenpracticalityand 100%accuracy.
And, we also havea lot of experienceon Judgementof whether the
muffler we sent o+t to our OE_lcustomer _dll
or not,
tie have a very good idea If
pa_s the drive-by
It will,
Ha're just
test
like fir.
0ou9 Rowley said when he got 95_;accuracy. I don't know llhother!
_uld have 95;_occnr_cyor 11({;;
accuracy but I tend to agree with hlm
that there Is somecorrelationbetween a bench test and (rive-by test.
If we cannot get some kind of ball park feelingfrom our bench test
then the O£litruckmuffler n_mnufacturers
simply would not be In _he
business, liecannotsend five mufflers for'our customersto test and
for them to pick one, They are not (]oln9to do that. llomend h{m
one somotl_s
At most two _n(i we make oar best Judgement whether he
will test It or mot, _!so, we do not send oflemuffler
to one manufacturer.
Fe send a _ffler to possliJ1yn lob of manufacturers. And from our
experience{f tilemuffler mhich we Judge {s a good muffler probably
will pass tile _e_t _¢ltha lot Of our cu;,tomers,On theother hand.
a had muffler probably|tillnot pass the test.
Ernfe Odde
Thank you very _ch,
Pober
N
57,4
Larry Erlksson
[loll,I had o few general observations,o little bit over what Peter .
said and what Cecil saidj looking at those vehlclecatcgories one
observation I'd like to rn,_ke
most, Is that many of those oategorle_
are products that either have been or will shortly be governadbv
some new product floisoregulation by EPA. And l'd like to focus on
that n little blt. One of the observations I'd like to make Is that
for those products I personsllydon't see the need for muffler labelled
for the new productsand I thlnk thls Is an importantpoint, lit're
talklngabout o truck or whatever that _a ofready subject to a rlCW
product regulotlon. I for one feel It would Just odd complealty to
also ask for n label on tile portlcularmuffler used on thI_ piece of
O_llnquipmcnt. It's alroodymectfn9 speclficationfor the overall
vehicle, Accepthlg that.pointthen what that leaves is the oftermarkat.
And, In tcnns of the aftermarket the ooly observation! can make Is
if woare
setting levels for overall vehicles,new'productsthat arc
as str_ogentand _5 accuratelyineasured,etc. as w_ are for trucks,
buses, or *that have you, tt
seems to rne that any aftermarket
evaluation
proceduremeasore ouqht to be eL least ccwaparobleIn accuracy. He
_houldn't_llve away an _wful lot In terms of the aftermarket measurement
procedure.
Essentially
what tie ought to be shooting for is something
thnt is more or less equivalent
to oEr4and the OEI4ontt that the OEII
equilx_nt
has,
of that product,
hi the sense that we don't
some aspects of not allowing
requirement
went to allow any degradation
that the EPA's proposed reds already have'included
any degradation,
l frankly
see the
In the aftermarketending imp one way or another.
tn so many words tt's
9o|n9 to be about like
that fact _nd the fact that
,_ayln9
the O[_l unit w_s.
you want an nccurate test
Accepting
It s_ems to me
that yo*_'re._olng to be lookingat _n actual engine test of onq sort
or another, r]ow,! _9ree tdth Peter, ! think the SAE Procedurethat
we have worked up fs probably not too bad o compromlso,.hutwhatever
yea come up with I think it's .qoJno to have to ha _omethin9 very
slmilor to that In order to obtain the klnd of accuracies to be
17
consistentwith the rest of"the program, And, ] have not seen
hl any other presentatlonoinelndlngmy o_u that the other four
tnchnlqoesllsted here really provide accuracy thatis at oii comDaroble
ta the rest of the oolse progr,o,,that is at all cn_nporableto the type
of thln_l
L_ecan achieve In the 5AE type procedure,ulth the type of
engine dynorneter
and real engine close to real system type of test.
tlovl, If you're
still
_.dth me on that _dlnre that
leaves hie, is saying
that okay, _m'ro galng to do real engine testing,tlo'regoing to test
on somethinglikeand SAE test, but what about theJ_Mtltude of
e_,hinatloos. It'sbeen stated, it seems to mo If anyobservatlonis
correct,that tl_oreis no praetlcM way to measure ,111 combinations
that
exist and so it strikesme that *_e'regoing to he in o sltoatlon
wtleresme kind of certlflcatlouthat it meets is o preferableroute
and thena te_t programIYouh|have to book up that certlflcatlon.
Tileburdent¢ouldbe on the man who certifies it, to the muffler supplier
to havehl_ englncerlegboule In order sufHclently so he can certify
it and he reasonablyconfident that _llenho gets oro.nd to te_ting it
on an eoghm or tlhon,s_]ebody
else gets around to testing that partlcular
situationon on engine that wltlHn snnletoleranceit does In fact follo_
what he said it _muld. So those ore a bunch of observations_hich
are connected.
£rnte Oddo
Illth
refe_nce
to ,gel. 's c_nent
accuracy of that
before on the S/E procodure_ on the
procedure, would you stt11 consider
procedornaccurate
enough for this
the nell SAE
purpose?
larry Eriksson
I d|dn't
really
disagre(:
that
much with
Pout,
maybe it come out that
way I don_t know. The procedure Is a very good procedure. Itms an
accurate
procedurn
In a sense
that
certainly
I f_hlnk oll
of us tn
the mufflerend of things at least in this panel, ore nsing, so_mthlng
very similar to thatproceduretoday In our _uffler testingand it
certainTydoes correlatein an indirectsort of _Yaywith tilekind of
measurementsthe vehiclemanufacturermlgtithe making. I guess I'm
51.5
18
like
Peter,
certainly
I don°t kno_l wh_t percent
Ile do supply
is Exact]y,
units to our customers,
are no proble[_s tn tornls of correlating
tile correlation,
and often
our numbers _tth
but
times thern
their
numbers,
Occasionally,of course, there ore, but there is certainly room for
Inlprov_ment
In that particular area. Iro_tevEr,
It seems to me it's
far-and-away,
that
from a technical
IYe'vo found and usually,
point of view,
the correlation
tile best 1lay to do it,
is quite
satisfactory,
Ernte Oddo
Thank you, are there ony
¢Olllllnnt$_
Dr_ R=ohfnAt fredson
It seems to me thata fairly easy measurement to make In the laborotorv
anyway Is the measurementof transmissionloss. And the question He
really have to imrk out Is how good is trons_issle_less a measure of
performanceon an actual vehicle, flygonss Is, and It's really only
a guea% that transmissionloss is probablynot too bad for the large
multl-cyllnderengine _Itoatlon. That% only an Int_fttvagoess.
I believe in the single cylinder or two cylindercase
transmlssionless is very onre61leb]n. I suppose on the average if
you're me.asurlng
transmlsstc_ loss for a large multi_cyiindertype
of vehicle thatmight glve you an Indicationof the performance.
A little bit llkehaving your feet in t_o bookers of _tater, llove
one foot in a becket of water that's freezingcold And the other is
bolllng hot, },gocan say on the average it's warm hut It's hortlng quite
o blt,
I don't have any strong feelings,perhaps some of the manufacturers
might have. If you do havoa !foodmoffler,and I In_glne that means
good in terms of transmls_ionloss perhaps,can you be reasonably
cartaln an a largo number of vehicles that on the .hole it performs
I-/O11, ,qy feeling ts that probably Idth a larger multl-cylinderengine
that h_uld ba the nose but certainlynot tdth the smaller configurations,
5].7
i
]9
Dau,_Rnwley
l*nloot gOil|gtO try to answer thatquestion. I don*t happen to agree
with that.
I'd
like
to _lo back to Larry,
Peter and 0Ill,
obviously
one of tilereasons I ranted to knowwhat your goals are is to establish
a point that we will be faced withreplacinga product that Is eqnivalont
to the original egulpneutand yesterd_wfill1
Roper mentionedsomething
about replacing the exhaust pipe ulth an equivalentto tileoriginal
equipment. I think one thing we as part of tileIoddstrydo not itlsh
to geC into is plachlga standardon the exhaust system, Roally,
_hat we're trying to do is controloverall truck noise, which, perhaps
exhaust noise Is a very significantpart. The question is, ai1dit cou|d
he a little bit ridiculous,are you going to pot a standardon the
mechanlcal noise in the engine, intakenoise, fan noise and eta, Hell,
thls is pretty much what I'm drlvlogat, I do feel thatif our catalogs
should say. as a guide to tile user. that
this is
equivalent
to the
original equi_emt, really to carry that on further, is t}mro a need
for o specific type of evaluatloneethad. Perhaps &here Is, bntyou're
coming up with an assessment. I could perhaps look at a product and
say troll',
yes based on a lot of oaperlence tllat's
to original
equipment.
Do you got what I'm drlvinq
going to be equivalent
eL here hill?
Fur instance, to meet the ()3dDA reqnlrcrnont
_m may havean exhaust
system that controls
tile exha,st
noise to 80 dBA or In another case
we have to control the exhaust noise to 70 dI_A. A vast'dlfference
probabl_,In the size, shape, weightand the cost of theexhaust
system.
And really,
when you get right
do_n into
the truckfn@ business.
this Is the name of the 9aloe. TheyJLIstapt by with as little as they
can possibly
Qill
use.
Roper
I think
tn your commentsyou bro,ght out one of the polnLs I think
important.
That is.
knowing wimt the exhansL system will
do on a
particulartruck is vitally importantto the person.who is uslng that
tr_ck, You mentioned tileone case you slted. The one case m_ght be
an BO dI_An_ffler and the other ca._e
was a 70 dflAnn_ffIerto meat o
N
518
2O
particular
desired level
of total
vehicle
noise.
So it's
vital
to
the user of those two trucks to know idlIahnluffleror _,dMchexhaust
system to apply, And I think that tilegeneral thrust of a labeling
program is Just that. To provideto the purchaserof tileproduct,
Information
that will allo_l him to evaluate the acoustical
performance
of tile product he ts buying along with
over,
q_lleter
i dontt keollD I guess It's
muffler
tlherl
not trlle
is always the IllOSt expensive.
So he wouhl have the acoustical
tnforll_tien
the other
he
illUkeS
a
that
things;
ill a general
So_etIIIleS It
performance available
decision,
cost,
or whatsense tile
Inn*t,
along wltll other
Tile other potnt you raised there_
tS oth_r cc_llponeetsOf the vEHcle are tfllportallt,
As I recall,
inv oponinq
remarks pointedout o couple of things that are particularto tileexhaust
i
It is replacedon o cyclic basis throughout the oseful llfe of the
system. so
That
Is,
It's an Importantsource
ofon
ooise.
product
that
itone,
Is sor_thlugthat
a oser later
In theTl_o,
llfois
of that
that vehlclewill be replaciilg
and If it Is replacedwlth a system
that is acoustlcnllylouder It's just a louder soorce of noise in the
environment. IIolngIn the noise control business we're concernedabout
that, so it's for that reason too we are Interested in coming up wlth
a way of definingthe performanceof replacementparts, Exhaust systems
fall into thatparticularcategory of a product that Is In fact a
replacementpart, to a totalvehicle systole.
I)wlght filaser
I think the one thing that baffles roea little bit on what seems to
be charged here of this three (lays.Ympeslunl
Is thatmaybe It's the
next to the.last
llne there on tilescreen, everything seems to be
pointed to,
lardchnracterlzn!lthe perfon_w_nce
and we all seem to he
charged wlth_shlchtechniqueIs the best to do that. In order to
decide which techniqueIt set.msto me, that first you have to define
which performanceparameterarewe going to ose to characterizeIt,
Let's even limit it to the ncoostic performance. I feel certain that
of all tilebench tests, analyticaltechniques,nil the on-vehlcle
tests, they've_11 been carriedout In a very systematiccareful
I
manner, they'reall rolatlvolynccurnto for developing data llhlch
519
I,
:
2]
refers to a particularperformanceparameter, It looks to me llke
what we really have to do ls to define or decide l_hichperformance
parameterfirst thenmaybe we con back off aud loDk at which technique,
if you wish, Is the most accurate, to muasure that parameter,
Ernto Oddo
Respectfully,Iafnasking you the question back a!lainas a panel.
Taking Into account that youJvn dO_lea lot of reseorcil,
a ]ot of
work in this area, and you'rE familiarwlth tileInportant parameters,
which should or should nut be includedin any bench test methodology,
Can you eliminateas maybe less significantsome of these pnranletcrs
to come up with o simpler bench test and still meet the objectives
hero.
Dr, Oavies,
I don't really
feelit's helpful to rnpeat what one's sold but I think
a lot of things said In between on a remark I mad(;Earlier and a remark
I make now ts along the same lines.
The point
get anywhere, that we've qot to state
and this
mostly,
is what Doug I(owloy said.
in
this
discussion,
is,
if
some objectives
we're going to
very clearly
_le'vo heard ahout heavy trucks
That's
only one part of the problem.
how w_ know what the obJective_ are.there. Tileoperator has got a
tough job.
To meet the noise requlrcn_nt
know the engine noise that's
legislation.
|lecause we
the. carcass noJoe is SOdominant,
that's
one particular
prohlnm, and the methodology you want and the problem
that tim _ffIor designeri:ifacing is in one cate.qory, llow If you
talk
In terms of total
environmental
pollution,
the priVatE
autemohile,
the problem is quite different,
that
is on exhaust noise dnmlnated
area, as for as the environment
ts concerned In general. That'svery
much more difficult I thinkj tile replacementprohlnm_ hecause there.
are morn replacements,that are going to happen in the life of the
•
auto. 5econdlyp the rep1_cement'sgoleg to be i_Idein a much e_)ro
m
m
arbitraryw_y. A private individualms going to put a replacementpart
520
h
22
on, that he can get cheapest andquickest to getting by, l mean that'o
the answerfor theaverageuser, That'sa differentproblemand If
you're going to try to comeup with o methodologyor a Lest procndore
l thinkyou'vegot to lookat eachof thesecntogorlos
on the llstand
in thomatrlxand sayollrlghtlot'splckthe parameter
for thatone
toldplace themethodology
on thatone and let'sgo on to thennxtone
and lookat thatand thenyou makeprogress.
Ernle Oddo
Good observation
and if yon'dli_.to continuethatdiscussion
-LarryEriksson
To carry on a llttlobit on whatD_dght's
c_elentwa_. whlch I think
I heartilyagree_dth. It'svurydlfflcut I thinkto sspnratethe
technical questions from questions of the ohJecttvos and what the EPA's
trying to =ccomplish. _dly they're undertaking this progrsmin the first
place. I think you've got to got very specific ubo¢t fly this program
Is beingdone. Specifically. whatit'S trying to respondto,whatit
hopes to accomplish. I knowwtth our mm c_pooy there's one excellent
way to waste _ lot of time and get a lot of wrong tnfom_tion and that
Is one of the personnel in our compnny,whoever it might he. so_one
from our sales group or engineering groupwalks over to someguy in
our research depnrbnent _nd he 'asksson_ question of our research guy.
howdo yo, do this? And .nlesshe (Jets very specific about _lhat he's
really going to do with thatinformation and i/by he wants It in the
first place, chances are the.ymrenot gOlll9 to talk tile seinelanguage
at el|, they're going to got a very strange answer. And the research
guy may be operating from e totnllydlffernnt
point of view. I think
the nail' way tie can work is you've got to haw:n person who's asking
the q,estions to give you all the bnckgronnd, l_hat Is he really looking
for? t/hat is he trying to accomplish? And this has been lacking. I
havefeltthls is neededforns to havea hotterideaof exactlywhy
,
we'retryingto do all this. {(rm.
that'skindof e cop-out,flowpart
Z ts theSAE _oheorrmlttee
to n certdne_tentans_n_red
thatfroth
their
_0
m
N
521
23
point of viers.Their answer frolntheir point of vleu was, wo want the
sound pressurelevel Droducedby thatexhaust system. Our eubco_llllttce
had to deal with that, not from a Oovernmentregulatory point of view
but from the pohlt of view of n group of enqlneers tryin9 to provldo
some reasonablecharacterizationsof exhaust oyste_s so we had to anst_er
questions
fro_ It)at point of viell,
Regulatory
aoonctos are sonlothtng
else again, l have not heard that, from the EPA. tlewore looking
far,lard to the question
question.
session with EPA, because that was to be my
Peter Chnnq
I'm not tryingto answer Lnrry*s question to EPA for EPA but ] Imagine
one Of the objectivesin the muffler ]abolln9 proposal probablyis
because thereare many mufflers on the streets which are basically
tie cans. He can labelmufflers In a very strict sense, put aria,
B, C, D on Itor we con label the mufflers
broad sense.
in a rather general In a
That is, in the very first step the EPAwnuld reqMre
each aftermorketmuffler manufacturerhave a good test facillty they
would have to know what they are doing. The EPA can somehnttcertify
their test or toeir test motbodology. In addition,EPA would have to
to require
theeftomarket muffler
co_panles to report the test res,,It=
to their consumer. I personally believe that EPA should adopt these
two steps aBd then wait for awhile and then see whether tbere Is indeed
e need to label the mufflers In a strict sense.
Dr. Se_'ber
t
lee talked a lotabout non technicalthings and perhaps I'm not quite
as familiar
with the rest of the people in rooard to sor,_ of those
questIono. Robin Alfredson
touchedon somethingI don't think that we
have receiveda satisfactoryanswer for antithat 15, how can we use
a basic muff]ordescriptor such as transmissi_ loss. /Iaybonot on
t_s own, but modified according to some particular
,
522
configuration
with
I_,
:,_ r _
,:÷,T
24
exhaust plpe or tall plpe lengtlls
and englne configuration,as a
de_crlptor, I don't thlnk anybodyhas really de_onstratodthat this
cannot be done, If we do hoveo proper descriptor for each of the
subsystems of the overall exhaust systems.
Certainly
transmission Io_s
and insertion loss have e lack of correlation.
Transmission loss with
more dnflnttive informationon the rest of tilesystolemay be on adequate
dnsarlptor, Ho haven't proved that It Isn't, That's one thinq I would
like to see pursued.
Prof. t)avles
I'vedlsaoreedwltilRobin before so I'll disagree age;to. Can I refer
bank on the three days pest, to my original presentation
tnwhtch
I polntndout that an outstanding proble[1,and this affects
the Issue elltechnlcalaccuracy,is that w_ do,'t really know ho_lto
categorize the source and so we're really in the dark, You cotegorlzn
the source and you con then categorizetllerest of the system, Fine=
if transmlsslonloss Is it. That's
quite satisfactory,that's nlce
ea Charlle pointed out, It's Invorlnblefor a particularunlt_ thatms
nlen too, you can lol_elit. as he snld gold plate the label and shove
tt on there.
In fnct
Thnt'_
I don't
line operator
grand, vastly,
know tl_t
but we're
we ever
will
It ke_ps these vehicles
Jazz then yon're
talking
turkey.
not in
that position.
he bncnasn if
you take till
on the top line
If you're
inking
_nd all
top
that
the average user
and portlculnrly,mnd _leilnvenlt
talked about cars much In this
dlseusslon,the average drlver of a famlly car. he'o not going to
keep that In the shape that ol1 the accurate maasurerW_.nts
and everything else are made in. And so, talkln._ahout one or 2 diior hlgll
accuracy or whatever Is meaningless,
it
the source is not going to be anything
doesn't
like
mann anything.
Because
the 0[11 source the vehicle
was when the vehiclewan categorized. It's going to be different, I
thlnk You've got to go hack tn _omethin9thnt will provldn the consumnr
with the data rather like the truck operators ore providedwith data
by the equipmentmanufacturersand they make tiledecision1_hichmuffler
to buy and to put on their particulartruck. It'stheir
decision,
In
i
25.
the long run, Youprovide t#_ legal authority, the policeor whatevcrj
with n test procedurelike the 20 Inch procedure for dechHng whether
the individualsare complyingwith tilela_l. And, we've heard About
the difficultiesof providingA simple bench test procedurefor that.
So that'swhat you've got to do and l thlnk you've got to be specific,
Put there's no way of stampingn label on n particularproduct and say
that's going to alttays be satisfactory.
It's beeq said several times
and ! agree, there'sno such thing as o good muffler or a bad moffl©r
excluding
the tin cons,
Hlthout soy|rig where and how and why y_u._re
using it.
C.ec
!I Sparks
I Just want to second that
and the way
your
first
quoatton Is worded
it sa-ys that the predlctlon has to be in A form of An eebml noise level
so It can be added to the other noise levels frc(n the o_her vehicle
sources so we Agree that sc_noof these more erudite
inherent
muffler
muffler
characterlst|cs
performance than something llke insertion1Ass.
gain9 to 'be able to usp. sornethln.q ltkA that
So It's
After
definitions
more of an evaluation
of the
much more adequately C#leracterlze
fly wife
Isn't
and very fe_ people will,
process of what -you do with the data
-you get it more so than bow -you get the data.
Ernte 0_o
That'S
true,
that'_
an important
the panel members ll_e to c_ent
an-y other
vehicles other
Part of the contract,
on those tim questions
tlould any of
relative
to
than autos and trucks which is more or 1ASs whet
we have dwelled on here.
Dr. A1fredson
I thought I'd
just
_ke a point here which really
but the manner tn which a vehicle
"
to the amount of noise.
recreation
vehicles.
is driven,
This ts partlcolarl-y
i
524
ii
..........
isn't
very relevant
can make quite a difference
Important for .the
Or.
[Iraeloor
A conmlcnt on the small engine vehicles,
! think
tile technique
employing
so_ form of onfllnosis highly preferable to those that don't, so
if you _ant a constant [measureI would use one of those. I don't know
whether the panel aorees, but iJe'voreally _andored around and I don't
think we've got anywllere. I thlek if one simplifiesthe question
perhaps In the way I suggestedright 'Inthe be,lnnir_g
we miqht lead off
to some direction, that Is of course ass_Hog there Is a need In some
way to control the productionof mufflers which is what it boils down
to, Control the perfonnanceof mufflers I should say
This can be
oithor by s_ee form of self certificabloothat this muffler is bettor
or worse, backed up with some testprocedure_ddch could be used as
a _thod of arbitratingbetweena manufacturerperhaps that clalms it
ts
equivalent to the existing
one and perhaps a consumeror in
th|$case the reg_|latlon
agency that clahns tilemuffler is hi fact
superior or inferior. All of tilequalltatlvedescriptions thatI
have used will be turned Into quantitativeterms snch As equivalent
could be "forexample ._5 dllof original equiI_Fleot
for example,and I
thlnk that If _re'regoing to n_ko proqress on these quostlon_I'd llke
to _oe us sort of direct the discussiona little bit, somewherealong
these llnes.
E?nle Odd__o
I don't knOW if panel members are familiar with the two testingInstitutes
In France and Germany. The one In Germany I'm referring to is the TUV.
Re're been in correspondencewith IIeinrIchGillet C_npaoy one of the
Gennen rn_nufecturers
who makes mufflers far various vehicles, They
sentus a lot of informationand data on these b_o Instituto_that
do testing
for th_ respectivegovernments.
I believe they're
not'government
Instlb{tosor testingaqencloshut
they..ere
certifiedby the governments In cactione of the countries.
They do have a scheme and a processwhereby If a company wants to sell'
apaftermarkeL m,lfflcr,in either country he must submit that product
525
-
27
to the appropriate
testing
]astlLute
arid that
tasting
hlstitiJte
a stalldard bench t_st a_othodology to evaluate the ,_ufflers.
uses
The test
ls all A, B type colnpartson in _lhich they co_;ipal'ethe flEI,I r,_uffler
the
rep]acenleat
fflLlffler
interpreted
tile ,lrtlclos
as
part of the
fully
yet,
[lmethodolo!ly.
_te
to
haven't
since I,;e haven't had them fully
translated. Ilejust have selected para(iraphs
thathave been translated,
There is an Indicatiollthat theyuse a startdard
anginn as part of the
test aloLhodoloqy,ilewill FOIIOL_
up o. this Infnn(lation
after this
syInpost
101h
C_c]l,Sparl:s
i]utthey're not taking that to predict fmlse level on any arbitrary
corlflgurationthatyou have In*:lhldthereafter. So I agrne, that's
a reasonableapproach. To qualifyyour r_Liffler,
Ernl_ Oddo
IVP.]], that_s what fie have to fIIId out_ _dlat qualify
Irloa/l$,
lie doa't
have the articles fully translatedb.t if any of the pane! mi:inbers
are f_mtilar
with those testing
rllethodolcgles and idiot
they _lean
we_d really appreciatehearing,
Prof. l)avles
I dondt knoL_about th(!_ebm but hl England It's the I]otorIndustries
Research Assoc. and thny do perfarlll
this f,octlon. And I can state
quite
categorically
riley don't
use _l standard engine hecaase I Lnn_l
it doesn't work. They are certifyinga productor a range of prodaets
for a specific vehlcie and that's Lhe way they work. They provide
the certificate. I think also that from_hat I've heard in this
me_ting| from all the l;_inufacturnrs
lne|odlngthe rep_acnzr,
ent alanufacturersp they do provide scx_e_ort of cortlflcate. And I thinklYe're
getting hun9 up on technology. Can I get hack to what ! sold in the
heglnn|ng, if you go to buy a i_ashoror cooker or uhatever that's
• '
certifiedwhen you i_uyIt.
Ifyoamre gotn!l to hay o recreatlnna}
device like a hlgh-fl svst('r_
that'sreA]lv certified, [ really can't
understand what: they I)llt OO the documentation hut that_s certified
i
4)1 right,
The nanufacturnr
p.ts so much (lope there,
_xe
l,
If
lie dhln't
1,
2U
comply you'd get him.
responsible.
I_ell,
You know for eon-compl]amce,
there's
nee point.
After
at least
he+s
and secondly you go and
buy whateverjunk you llke and put It Illyour house but if that
doesnatmo_t city regulatloesthat's your responslbilltyand Itas
not the soppller'sfa.lt. So I'm saylnq, the re.to to follon Is the
suppller,provides the certificate,and I thiok they'rewilling to
do thls_ and the user Is responsihle to seehlg the compliance Is
agreeable. How, If the user's worried it's up to hlm to approach
the supplierand*say, look+ If I risethat product am I going to get
bombed. And he'll get an answer.
P.Pe
ter C h_ng.
I wonhl Ilke to agrilewlth Professor Davies and I would like to
amplify thatpoint showingour extremes. In the State of Florlda().r
oftemorket custc_mrswould llke to buy hlgh performoco mufflers
milreso thanmany other states for the simple fact the State of
Florida has a rather strict enforcement.
tarry
Erlksson
Yon merit]lined other
think
prodncts
and I think
yo+_shm|ld say for thil record that
It's
probably
ehvlous
hut I
tllere are a couple of othilr
things oil these other products that aril extremely Important to COllS]der_
tileobvious one, parLicnlarlyfor motorcyclesand sool_nobile_
Is the
extremely
strong coililect]on between the sot+nd level
of the eXIlanSt
system and the hor_ilpower.CertalnIy the exlla.Stsystem ]s cilnnected
wlth the power producedhy the enghlilfor all of theseprodnets bet
snovanoh|lils
and nmtilrcycIils
is of snch ildifferentorder of maonitude
con_idilration
in my mind that that truly has to be consideredseporate]y.
The other one would be in the automobile
area Althonghwe're not
involved Inaatomohile mufflers It's certainly tilecasilthat as I've
been to]di_ymy friends ]n tileindustry there that subjectivecons]derattons,
and I think win'reo11 aware of th|s In terms of antomilbHe
mufflers,are At least as ImportantilsilbJilcttve
measurementsand I
th|nk that's fairly unlqne to autGmohiles and perhaps It does carry
over to somil of thilother'sbLJtpartlcnlarlyso In antilmoblles
that
,927
i
•
_+_+t,_++_,m,++.,.,+,+_
..........
++u, ,+.+._t,,,.
++.+-_,+
++...;._
......
_.
_ +_.+u,t_;+_,(++.,i+.+L+t.cl+:+_;++t_,_+_,+
29
in terms of nhat's good or bad for the cons.mar a 5ubJectlvecharacterIzatioo does play a pretty importantrole in terms of whethertlle
consumer flods this to be a satisfactorymuffler and I assume tbls is
tilekind of thingwe're shooth19at In terms of regulatoryActivities
as to son}eho$t
satisfy the consulnerIn terms of what he buys. So I
think the subjectiveaspect Is !IolnUto have to be looked at if you're
out to do thatfor cars,
£rnie Oddo
At this point I believewe'll open up questions fronltim floor.
Don )_hl
tony
I think I'd liketo bring up a point that I don't think anybody at
this conference))assaid. Homely, that we already have labels on our
m_fflers, No all have part numberson Lhc_n,those part n.mbers
refer back tocataloqs, those catalogs go to the individualman_¢factui"ers,
the muffler manufacturersalready keelsthe performanceof those mufflers
In relation to the perfere_nceof other mufflers that they themselves
have af_Jthey have a pretty darn good Idea of what those mufflers do
already. I imuld like to add one other part tdth respect to the SAE
test,
as I understand it in terms of an In._ertlon
loss
test I really
don't Agree particularlythat insertionloss is the thin9 thatwe
want to measure, floweret,in termsof comparison of one muffler wlth
respect to another, I think It candn n pretty good .Jobof tolling us
equivalence on a ._ysta_that truly dpplicateswhatever the vchlcle
with its
do.
point
e_haust pipe lengths,
tail
pipe lengths,
etc.
I think that we can ask a question here relative
that's
conmup marly times and I would like
do _na_le to
to the accuracy
to turn the question
around insteadof saying bow good is the Accuracy I'm more concerned
with
how bad is the. accuracy from tile standpoint
that
it's
fine
to
say that n muffler is approximatelyequivalent to the muffler that
ml,qhthave been on the oq_i_ent in the first place but I worry when
we say it's appronimatelyeq_|Ivalent.Is that accuracy good,dn I
have to pat in a stnndanldeviationof 2 dfland then in order to
_nufacturo a replacen_ent
muffler and satisfy _lyself _lithscale reasnnable
confidence thatmy ee_imuffler will be belmt or equivalent to, do I
have to design tile new one to .5 dfl below, or _lhatever.
5_
Ilol: bad is
3O
tile correlation
I'd
like
ts of more concern than hot/ good ls the correlation.
to reiterate
again it's
tile porfornlanee of a muffler
been nlentioned several
on a particular
times that
engine does in fact
affect the power but l'd llke to also say that It does affect emissions
also since tilepressurepulse is hack on tileengine ;dll affect tile
instantaneouspressureat tilevalves, etc. And as a resultwill affect
ti_oemls_ion cilaracteristlcs,
lle'regetting into a dual regulatory
situationwhere _le'vegot o lot more than Just sound levelsto
consider. I think that's on extremely Importantthing. Just th_
fact of possibly putth|g double testln0 in terms of requiringan original
manufacturerfor the full vnhlcleHhlch Is _dlatI'm involvedin, a
double test, I _ould say thatId_eneverdouble testln9 Is involved it
in_.ffoctlvaly
decreasestilelevel to _dch t_ehave to manufacture
trucks. Using trucks As on example simply because you have to meet
both standardstlIerofere
the total truck noise is lecternThor might
be a d©sirableobjectivei)atI don't think that's the way to go about
it.
I wuald llko to say thatwhile I don't necessarilyendorse the
preciseColt fernlaprocedure the J1169 SAt procedure for passenger
cars Is _ course fllter, It's dlfficult to get d(_Yllto proclse levels
in termsof
enforcement,hovlevorD|t cap do A Job, it
can do a real
Job more than I think new tnJck or new passengercar rcqli|ations
will
do, in
the _onse that those vehicles
aren't really
had rlgt)tnow
the on_sthat are really causing the proI_Ic_n
In the cor_nnnlty
are
tileegos that don't llaveAny n_fflers, tl_y have straightpipes, riley
have modified _ystems,that type of thing is the thing thstwe really
need to g_t rid of end while the JIIG9 for passengercars Is a toarse
affair and we all agree It'scoarse it's net a finn test It can do
a ver_/ effective
_oh,
flick Miller
Jl th|nk we neod to foco_ on the fact
that
are two areas heroof concern,I thtnk,
as lt'_
I)oen mentioned,
there
first tilosepieces of equlpnmnt
that are now sobJcct to regulation as new equipmentand those that
aren't, We're more familiar_dth those that are, so we'll address those.
52_
31
I thtnk tie need to rcmc_d)erthat durtnn the pro_lulgatton of the truck
regulation and all of" the other new vehicle regulaLlons both EPAand
tile Industry were oxtrcmniy careful to avoid any restrtcttods upon the
componentrythat's used to meet the standards, The truck regulation
and the other reg,iations ere ow._rall performancestnndards and this
was tile philosophy token so that eech manufact,rer based on hl._
understanding of his n_rket, co,ld complywith those re(juletions most
economically. IIot_, tile conceptof lnbellno a cmponent is sc_,ewbnt
akin to wearin9suspenderswith a belt. The vehicle regulation, the
truck regulations, madthe others thot are patterned after that, has
tempering provisions which obligate the user to use cqulpnent that w111
not (legrado his noise level. In ndditlon_ the proposed revisions to
In-use regulations will else provide someassurance that.on't
get out
of hand. ! think what ties ooln9 to happenIs that obviously the
n_nufacturers ere not going to provide eq,lpment that _lill rolsn noise
levels and the eftcrm_rket suppliers are going to be forced into that
positton !.st to stay in b,Jsiness. ! think this is n situation where
we can dependon the free enterprise system and elon9 with the in-.so
regulattbns to provide all the necessary policing that _ need. So,
! think we have to look at tile objectives that we had'when_ first
etarted looking at regulations for newproducts end mtlck with that
philosophy becauseI think it is a well formed one and ! think it's
been fe|rly
sueceasfu].
RossLittle
I have n comment
more than a q.estion. In sitting thro.9_t
this whole prooram, manyof the speakersappear to me,really aren't
addressing what we need or whnt's neededout in tile field.
He need as
I see it, to identify the aftern_rknt exhaust ,Syst_llwhich when
Installed de9rades the noise level of tile vehicle,
fie don't hey[=
prnblemsms a Oeneralr,le.withnew'vehiclom.So in the r_tin.q
system
w_ need a relative noise level which correlates t;n a sound level ascribed
f
530
,
.........
32
to the vehlclawhen the vehlcle is first deliveredto the first user.
That can be thesome test procedure or s_,e other _ay of arrivlngat
it, Tllenthoseere tlmemain things, there Is a standardbeing proposed
here for labelingbat son_Joneeventually In_sto enforce It and if the
nunlbersaren'tcorrelatable or SOlf_ethlng
that can be used, then the
enforcement goes deliathe drain,
whole progrmats
and there
ts no enforcement and the
lost,
}!a.vne
llareus. llotnrcycleInd_stryCnuncll
First off, in the regulations
that are under eonslderatlouno_ labeling
regulatlonsare naturallydirectly from the noise enntrnl act and 1'II
read you on0 relative
clause from that.
Section U, _lhich says, "the
administratorshall b.vregulation require that notlc_ be given to the
perspectiveuser of the effectiveness,of the i)roducts
effectiveness
in reducingnoi_o." So thls is what at least the Congressaud the
Presidentof the United States were lookinq for when this act was passed.
ilow_tn determining _tl_at
the effectivenessIn reducing noise Is_ In
my mind, we're looking not for a comparativenumber relative to an OEII
number. Hhetwe want ia to know t_hatis the reduction in noise from
a muffler, any muffler because certainly the OEIIproducesreplacement
mufflers as _mll as After-marketco_anles.
program todaywe learned
mufflers
Secondly,earlier In the
that even OEll produced composite or universal
for older vehicles. The replacementmnffier IndustryIncludIng
OEMrfploeen_ntmufflers, is as far as motorc.ycles
industry ts concerned,
Is from a labcltn9
standpoint,this
aimed at pre.effeetive
labeling
d_te motorcycles,
that
regulation 20_, should be
is,
m¢)torcycle_ which
are producedprior to the effective deta of the upco_ling
new motorcycle
and replacemente_haust regulations because I don't know if
youmre
familiar _llth It, if all of you are fer_illar withlt| but as far as
motorcycles are concerned there are t_Yosuch regulations _hich Include
labeling
provisions end which include noise provisions.
are coming up, very shortlywill
The ones that
set noise level _tendardsfor motor_
cycles such as other types of vehicles already have on the books.
This one, thatwe're coosidcrlng here ts purely for the consumer's
Infomatlon. Therefore, motorcycles uhtch are producedafter time
N
5_1
.
33
effective
will
(late of this,
beoontrolled.
nolsn emissions.
soon-to-be-announced
They_lIll
It's
bn contrnlled
the pro-effective
noise redact|on
to a certain
date,
rnqulation.
level
of
the ones that arc out
on the streets right nni_,those that have detnrloratlngmufflers nn
them at prnse_=tand those which have engineswhlnh have gone through
an nxtenslve break=in period and have dlffernnt
source charactnrlsttos
thanwhen they worn nrlglnallyproduced. So tdlatI=m InterestndIn
is knotting
how to ]onh Into and hot_to discovertdlatthn reductlnn
charoct_rlsticsof an exhaust system arn on these broknn-ln0presentlvon-the-streetvehicles,not necnssorllythe vehicles that are qolng
to be regulated.
!lartlnBurke - John Denre
I hove both qunstlonsof the panel as well as conmlents,
In the area of sno_mlobllns,
sno_obllns hove been regulatedby States
for o number of years nell,have o 78 dBA drive-by level per SAE d192.
As o result of thls fairly strlngentregldatlonsnm_htIemanufacturers
have had to put In unltlznd exhaust S.yst_s on the column in _lhlch
there ia only o single cnnnectlonhetwnon the engine and the exhaust
system that is a alnoln flexible
type cnnnectlon. Earlierynars ;;o
used to _¢e systems that had tvo or three Jnlnts In It and which you
could perhaps replace wlth various compnnnnts,
Since snet_oblles
ore baalcollydlffernnthotwnenmanufacturers,I glmss l'nlnot currnntly
o_nre of on outside replacementmarket on snot_obi]nsother than the
OEII supplying exact replAconmnt parts.
case of o=_rc_pany,
be Identtca!
IIhich wouhl I 9ueas in the
to or hotter
tll_n the original
ones.
end I s_y hotter than, it couhl he a case _here we cArrled a model
throogh=everAl years end becausnof the Increasenr reductionof
noise we*re hod to Improve the exhaust systnn_in those cases tlnhavn
replacedthe older systems for rnpalrs wlth tilenntlorsystent_,llo_i
whet decision does o customerI_ve to make If
system frnm one snurne for that machine.
i
5._2
ha can only get one
31t
Unkno'un
l'd llke to clarify ono point, and that is that it's Impracticalto
p.t a nolselevel on an exhdust system, llherevehicles that are
manufacturedto meet an overall vehicle regulationono manufacturer
may require more of the exhaust syston than enotberdoes. kn_ so
the only th ml that makes any sense is to requlmoeflulvalencoto the
original system. And that's_uch easier to get thena number to begin
with and it'sthe only one that's go n9 to make any sense to the consumer.
Frank Sava!_e- DonaldmoE
I look at tblsthing and there are throe parts to this whole question
tore. One Is the governmentwhich is responsiblefor settlnq tile
standardsand enforcingtilestandardsam! the manufacturerwho makes
the part|cnI_rproduct and has to and most stand behind that prod,or
as far as performanceis concerned. And then the consumer,and It
seems llke nhat we're doing here is putting the entire load or the
responsibilityfor meetln9noise reflulatlons
on the nanufactureror
the flovernment.I think the consumerhas an eqaal share in this
vlholobualnesshere. I think tbat the muffler manufacturerscan provide
a bench mark and I say bench mark because thot eliminates the occnrocy
type of qiiestlon
but at least it's n bench mark which he trillcertify,
that says thatthls productwill work on those machines. You've got
to make surQ that the consumer'
has not taken thl= good qoal'itymuffler
off and repi_modit with n tin can or e strnlght pipe. You've defeated
the purpose of course, of tilesllencer sepplleror the program or in
the case of the heavy truck nsorp where the shell Is still in flood
condition b,t all of the internalparts are ignored,bat you still
run it dawn tile mad. The second Lest that has been =_modwidely is
the total
vehicle
noise test.
llnw, I'm not
suggestingthat
all
these
tests be run simultaneouslyby any one person bat .th_total vehicle
notae teal Allows tile final
supplier
of either
the whole truck or tile wbnle motorboat,
to qualify through s_o
9_
the whole snmenobilo or
integrate
all
its
noise sources
procedurein Iliaown l'ecJl|ty.! think it's
been dE_nonntrated a number of times that
'533
If you want I;o flat a sound
35
pressure level
at some distance
in trying
that you have to use the actual
to use a beech type test.
engine ilitil
the actual
_ystem or a
systc_L that is qualified
to predict s_e sound pressure level at s_ne
dlstances. There Lvere at least tiloproceduresglvcu today by Larry
Peters,by a John Deere man _lhere they Ilad carrelatlou_llththeir
ol4n bmlCh testing
individually
to get them to fifty
could be certified
feet.
Of course, these facilities
by Era and then vllth published sound
|evels a certificate
could _o out that certifies
tested In a facility
certified
by Era,
tidal the silencer
i_as
Ue already tlave a meollantsr_
that takescare of not relatln_accor,_teInfor_|tlon/]lid
that's called
a guarantee.
Ar_lan simply has to ask for a guarantee and If
it
doesn't
meet it let's say a tr#Jck
muffler, if he buys one a_idtakes it out to
Hr. Iloss's test station nod it doesn't pass tl*e test he carries it back
and gets ills money back,
5o, that ailotls
dote to _o ahead and operate,
labeling
only in ISl_,
all
lie have dealt
|ndustrl_l
Silencer
the test
is and Inmany cases the silencer
to
Idth tile problem of muffler
llanufacturlng
I+e bare to deal reich ttldt because of tile statiollary
yon knnw_haC the exhaust pipe length
facilities
Association,
source, seldonl do
is or idiotthe tailpipe length
is purchased and .you really
don't
kno_1_h_t the engine is. From my o_inexperfence,,_ndi'm going to go
back to someof the things that Larry indicatedand llrl_laser from
_eneral llotors,
if you 11antto t,_Ikapples to apples, a s_mple comparison
of mufflers,not relating it the in-woe sowed pressure levels,because
you cannotunless it's on the actua! emjine on ti_esame source but If
you _Yantsmethlng llke the absorption coefficient,or tranmulsslon
loss classjb_hatis it? - AS17170tlmy give A laboratory _est procedure
And clearlystate thatyo_'l] get different
numbera tlhenyou Apply tills
to the field, If you flareto Pave _c_e comparls_n, tlfenyou _leedto
look at broad-bandnoiso. I prefer insertionless t_Ithno tail plpP.
and thenanexl_mwstsyst(_, exhaust plpe t/lotmielmf_es
on any silencerthatlm.ldbe
at an averageflo_
typlcally
rate for
tested.
And tt
the effect
_mnld /)ave to be tested
the mean end use_ f,e.m_t_obile e_haust
has much iliF_her
exhaust velocities tlnn In the stationary
engine and It would have.to be teated at.some average or mean temperature
for the end use, tlds is particularlytrwe for an engine exhawst versus
An engine Intake.
i
534
13,
,,
,'
36
(
Ken
i'd like to make n co.menton these procedures that, if the.vdnn't
Include
l|ko
shall nol_e or pipe noise or leaks clue to clamps or anything
that.
they aren't
9olncj to be accurate
and we have to ask ErA
uhat accuracy we're lookin0 For.
Ernlo Oddo
Tllank you.
This ts tile last
call
for
qucstions
for
the penal I_..tle
we have them up here, llewill next 90 into th+ethird pert of otJr
program in which the ErA irlember_
Nil) replace the panel tllL_nbers on
stage and we will open th_ Sessionwith q_wstlons frr_ltilefiner.
Panelmembers_ we thank you very much For your partlclpatlonIn this
syfnposfum.
A reminder to everyone tiler we wtll
be publish|n9
s_nposi,m to the very near Future.
Everyone who attended this
certainly
=all1 receive
a copy of the proceedings.
proceedings of this
sympos|um
P word to those
people who gave papers at the symposium, please send copies of .your
paper, with art work to _
at i_cPonnell Dou91as in California.
Fie
are assemblInq the proceedings for tile ErA.
At this time, we will
fronl
the audience.
open this
session far questions
for the ErA
IHII Roper
PerhapsI should pick up on someof the questlmls that were asked
earHer.
The one from Larry Erlcksnnabout what is the objectiveof
the _PA labeling
program?
remains the same as it
I think
was spelled
that at least
the general objective
out tn Line Federal Re.qfstcr llotice.
tilefour points that we've put an the board, or the viewgrapha little
earlier,but I thlnk specificallyrelating to exha._t systems,there's
n
37
two specific
areas 11here we _lere lool;lnq
and that was infon,ation
for tnfon:hltlon
on development of a statistic
at this
for
mcetle,g
a comparison
between two exhaust system or two [nufflers;
an A-l]comparisonwith OEfl
or _d]otever,
a relative cc_,pnrlse,o
bet_teentwo svstclns.The other Is a
stntistlce,rapproach for developing Information,statistic Information,
on comparison between a total vehicle level and the exhaust system.
llol.l
those are two general categories of informationthat involve
differentmethodolo{ties
and can be used In dIffer_ntways. And we've
had opinions expressedas which one is the hatter or the worse.
I
tlHe`kto be quite frank, in n government study effort such ns we have
under way here that we n)ayor may not lead to nny type of regnlation,
whether it he labelie`g
or eventually a standard,n noise perfomnnce
standard, it would be ]e`a sense dishoe,qstoe`my part to say specifically
what is going to happen or t_hat'snot _nlng to happP.n,lle're,
ce,llectJng
ie,formatlon
at this point, to define what tf_oproblem is and what the
possible solutionsare .giventhe general objectiveproviding
Inforn_tton
to the consumeror user, In this case, exhanstsystem muffler, that
he can use in the purchase decision. I don_t knm_ If that's a satisfactory
answer'Larry, but that's what I have to 91ve.you. Another point that
llasraised by %Hck liille`r
re(,
uardin{/ tileSituatfonIn the truck area,
Implyln9that there really wasn't a nee`d for thls
klnd of information
to be.conveyed tn the user, or purchaser of a muffler, I think ilehas
raised sane good polnts_ that is a good point In the truck area
.I _lonldlimit It to that portion of the truck industry that
ie`volvcsvehiclesthat are operated by interstatecarriers. I thle`k
that's fairly valid hecaL|seIn that area Era does have tileauthority'
to set le,-usestandards. There's only t_._n
areas _vherc[PA has that
aubhe,rltyandthat's fur interstatemotor cnrrloro,or vehicles operated
by interstatemotor carriers, and for Interstatee,qnip_tent
and facilities
operated i_yintnrstaterail carriers, So,orlon17 and lflle,the 'lolse
Control Act, So in these blo Areas and the rallroAdarea we have e,ot
set Section (3 new product
.
standards
that
apply to those vehicles
when
they are nc_t|ys_anLffacture(l.
He also have a thor ty in the in-use
area and wn have such standards. So there is a follow-through_o-tospeak on total vehicle, at least cr_tpliancerequirements, But of coarse
311
that t#ouldnot hold true hi every other product catenory that_as
listed Jn the matrix, Out again, I think ! unuid Uo bach and say that
Jt 2tIH rome|no h,portant for the user to have the infonnatlon
ova/laMe
to his
level
to i_Im that
truck uIll
and quite
the i;_uffler or the exhaust system that he'o applying
alice
the total
frankly
vehicle
to meet a particular
in looking at some of the material
been I)resc,ted by l}onai(Ison for example, Illlore they I th|fll;,
degree,
are prqvidhl!l
their
Nmt, one of the principal
of voluntary
labeling
of o product,
any Federal
objectfws
that's
hlvolvementl
In noise and If it
fine.
1 think
others some of the ramifications
perhaps in other areas.
for questi_s
ISdHa!ter
Uith
titat's
I
to respond 1 9hess to s_ne
hell)s clarify
tlhlt _re applicable
that
that
_lhat _le_re after,
can corm ahout _Hth vohlntary
So, l_ve _ttempted
of your con_nents Nick and I think maybe ttlio
a co.ll
performance
that occurs lilt/lout
tYl_lch Is one of our oth_r objectives
mentioned, rain|real Federal
programs,
the acousticnl
enooLJra_lng that and tf
_ovolvc_eot,
to a large
that type of lnfomattoo.
of the EPA is the encnuragcmont
l'lllteh I_ou]d describe
l{oll _e're
Mdch is a reduction
ousto_lers _dth
sound
that has
I queos lhl
for time
on trucks but not
open this
oess|on_dth
from tile floor.
. (]urr!ess
You do have promnlgated re.quiations,
proposed remdatlonS
Far air
compressors, that give n (1[I ievol that yon have to checl: _t four
or five point_ around the ec_lpressor and that Is a. overall
]cve]
including
a prime mover tthJcil Colfhl be an engine, which nndm_btedly
++uld h_ve some klmJ of a muffler
the manufacturer
service lJfn
maintain
co tt.
be It
that lev_l,
four years,
It's
for the life
_hoo It's
manofaetorod.
is going] to,
If necessary
those _coustle components uJth eq_lwleot
" "'
It
of
the unit.
that the _y_tem imold, nql,_e _lse,
requ|red
assum_ then that the manufacturer
s_e,
And yoa+ve also renulrod
of the nip cr_npressor to _arranty
acoustic
I _mahl
replace
CO;,q_C}OO[It_Of the
I _]uess the same m_nnfactuter_right? l(e_(ouldhave to if i;e
Installedthese OEH p_rts end he's _rranted thl% if they had any
problemsup the customerran a truck or dam_,jedone of these components
they have to be replaced i.tlth the same Itc.R that _tas origlnall.v
manufactured, Is that correct?
537
]9
gill
Roper
It _?ouid have to be replaced _t|th a co_lparable system colnponent.
me go bach a minute nov.1, On the portable
standard was promolugated it
the acoustical
didn't
air
co,lpressor,
include as I recall,
s,_hat_le call
assurance period of sonic period or time when that
would be required
to continue
Let
{/hen that
product
to cr]dt or nl_et the standard at lllllch
it i/as designed to _lleet tile standard at the date of manufacture,
tile later
tractors
regulations
that we recently
that the acoustical
Dllt essentially,
in tile standards require
imposed on wheel and crawler
ossgrallCe period
the_natntenance
that
concept was involved.
lllstructlons
that are incorporated
the Jnaoufacturer
identify
of the piece or" equilN,_nt that are key noise control
if
something happens to one of those c_tponents
Ytltll an equivalent
system tt
In
those coniponuots
coJ=_pmlentsthat
unless it's
_touhl not meet the standards.
replaced
Essentially
Idontli'yleg
to the user, hey look, here's a llst of things you better
keep track of and n.llntnloproperlyor Xou're not going to meet the
i
Standord.
l
P
Ed Ilalte_" - Burnests
Isn't
th_s essentially
',,
iI
what you're
addressing
hero _l|th renpect
to
9round _ranspartatlon. In otllcrwords, IF you l_ld 4 muffler as part
of a package and you have to replace that re,filer
;tltll the same type
muffler,
r'lght?
The easiest way to do that is replace It _dth the
r_
same Item D the same part flulnher, the namemannfacturer_ you f_ly have
to flu_llfy oilier suppliers If you have a monopoly prohlem to produce
_'
that same product.
!I
Bt 11,fiopo&
] think from our perspectivewe got into our gnnerai connse] Informs
us, a con_tralotof trade situation, If _tespnclflythatit must he
OEllreplacement. So we're looking at ways of identifyingthe performance
so thatanyone who prodncesa product that meets that perfo_anco conld
in factsell It, flareit applied t.othe place.'
of eqnir,
nentand if that
gets hack to what we*re talking ahent today, oralthat way callbe used
to characterize
I
_;%
!
r,
the performance,
In this ease of the exhaust svstc_
530
_, •,_,.,i_._lr,,. ........
• .
_:_ _, . :,_.!?,...,,
9t.
,
4O
Ed )loller
- IJ.r_ess
B,twouldn'ttheultimatebe thatyou had Lo qualifythaton that
particular
pieceof equil_nent.
Ioother_iords.
If you'reuoili_l
to
replacethison a crawlertractorandyo, hodo certainprocedure to
checkout
on ._crawlertractor,
youilouldthe/lm _n_of the replace(neat
muffIQrsor components
wouldbe testedelltheorailler
tractor
and
thief
sanle
method.
11111
l(o_er
That'scertainly
onektayit cmfldbe done. Probablytheeasiest
way itcouldbe done _t thi!i
time.
ErnleOddo
Another thing I'd like to add here. ConcorntnE_
exact replacementsto
the06/1,
we'vemet withtheautomobile
r_nufacturers
andothermotor
vehicle
mmnuf_oturers
and h_vodlm_ssedconsolidation
of deslon.
h widevariation
of m_nydifferent
desl(ins
resultfromcontinued
consolidation.
The endrosk41t
is a raftof m_fflersth=tare still
so-cellini
0_I equi_ent. Youmay finda $ddetolerance
thereIf yo,
ivould
actually
me=suretheperformsnce
of )hose(Ifterl_larkot
mufflers
and comparethemwlth theO[IIperforr_nce.
TherecouhIbe 3. 4 maybe
5 dlldiffer_.nce.
Th=t'sthe pr_ctlc_l
world.
Dou_Hcfl_nn- Ford Ilotor Co.
I'd like to clarify
tile
statment that£rnle J,sl;mado.from
re9ulatory st_ndpotn9 the afterm_rket m.fflersthat we prod.co ond sell
are equivalent to Original equli_nt.
The _ubJectlve levels h_v_ been
compromised
tn many oases,
539
41
IH11 Roper
Could I ask a question?
It came up tn the earlier
the automotive area, leaking
ls
at subjective
se_*stoe that
t.
levels was lmportoot.
that In regard to exterior, Interioror both?
Oou9 !!cllann - Ford IIotor
Co.
Both.
Jim Hoore - John i)eere
The snu_m,obtle indLIstr'y currently
labeling
program and Ilurtln
oorrontly
exists
view of this,
has a voluntary
O,rl:e brought
total
out the fact
veilicle
that
fla aftorelarhetIll snown_btlo oxhatlst SystoelS,
de yo_ think
it's
necessary to label
noise
there
In
sno_eneblle exhaust
systems?
IHll
Roper+
! think tho Inforr_tiorl
we havo been providedon snowmohtlos certainly
p, ts them in a unique situation.
ether areas anti that's
I thinh,
certainly
c_npared _dth some of these
something we'll
there is a need er not In the snm.enohile
area.
ta 9e back te tile point
at this
point in th|s
thatwe're
particular
and Ellis kind ef tnfernmtion
really
consider.
LIhether
Agaln, ! think ! _larlt
on a faet-flndin_
mission
area of exhaust cmtssfen I_orfonnance
is very useful
to us,
I can't sit
hera
and say what tim agency is going to decide to do on Lilacparticular
question hocouso I don't
raise
a q,estten
know, but certainly
that tnforn,ltton
weald
of ithetheror net it's necessary on snotm)ohJles,
gnu9 []owley - Oenalds_
l'd
like
te dl._euss this
tiler Ross Little
voluntary
out in the State of California
l+d ltke
action
relative
to _sk tllQ [PA the question,
'n
5t0
:i
bit
getttn!l
to controlling
Bill,
I know
voluntar.v _ctton
truck noise and
how you intend te got voluntary
action?
Ohv|ousl),, it must be through s_e
_'ou touch on that a bit?
l
a little
spent al)e,_t e year and a half
enforcement proqram.
Co,ld
r
42
I
BIll Roper
In response to that
looktng
there
I think
a_latn of tile EPA's standpoint
we would he
at _dlat's happening out tn the country mou. For exampTe, Is
an effective
voluntary
co_pltance proorar,_ nm_? As a result
of
say State regulations. An awareness on the part of the manufacturer
tltatlllsproduct is noisy and is adverselyaffecthl0 his sales And
causing hinl a ha|'rasstng
or i.illatever und that
problaa
because it's
tl_e industry
agAinst state
say has flottezJ to,ether
with a test procedure and is voluntari]y
certifying
re.qulations
And colon tip
or labeling
or
whatever their product to meet a specificnoise IEvel, liewould be
looking
noise
at ilhat's
hoppontng
from that portico]dr
_ome examples.
today,
and hml that
product,
In the snowmobile areo
• _here was _ lot of concern |fl vorioos
snot_noblins nod there
the
to do something
They did establish
that was.acceptable
Ydllch
snowlJolt states for levels
ohout lowering
perhaps others hut fr(_
be assessing and lookt(_9 at what's
to be (lone.
Section 6 regulatory
today,
from
That's
or settin9
just
a procedure
I think
gee example,
as (ze move
standards we would
being (lone now with that
Again,
noise
the noise perfomancn of their
£PA's standpoint,
into any area where there was labeling
and what's possible
their
or agree m_ongst the association
to them to identify
product and they have gone ahead And labelcd.
there's
and site
wns mentioned earlier
were laws passed and then there was response by
snov_fv_blle industry
levelso
relates to re(luting
I might go on furtller
product
I guess tze ore going to a
study which foamyof you may be Aware, the kind
of three prongedapproach tletake there and that is to ]oak at what
tcchnoIogyis Available,what's the cost of applying that technology
and what kinds of health and welfare beneflt_you get from applying
the various loyola of technology. He In the standardsand regulatlons
division are responsible for put(in9 togetherthe factsand coming
up wlth recomnndatlons for the agency to make decisionson and so
again, our Job iS fact
findJn_
end certainly
what's
going on in the
industryas far as voluntsrystandards is on importallt
factor that
would .qo into the arraying
of inforn_tion
541
and generation of recrgmendations.
43
Ernto Oddo
_/Ohave time for one or t_/ot1_ore
questions,
Ross Little - Clip
I have o cof_nnt on snoLnnobIles
- To begin tilth,I don't knou anytblng
about snowmobiles. _le regulatethem but IYodon't have many out in
California, fortunately, gut I am hard pressed Co believe that they're
as innocentand pure as they are making out to be, I b_g your pardon_
but I know they race sno_nobilesand If IIooherindustries think they
can (totanother ounce of horsepo_rer
out of the soo_oblle wlth an
uns ]lancedexpa,slonchamber, that's what youJre going to find on It.
And if they'll race with thnnl,they'll also rlde out in tile_zoods
with them.
They do motorcycles,
!It.1 1 Roper
That's
th_ other side of the coin.
to that slde also. Although
the snm_blle
tllore
tie're
looking
and _e_re sensitive
appears to be some difference between
user as a general group and motorcycleusers as o gnnnral
group based on the InformationHe'ye seen so for,
Jim tloore
Just a slight rebuttal to _lhatthe (]entlemen
In saying, It I_ certainly
t_e,
there are expansionchamhnrsand stuff Availablebut I don't
call those silencednxhaust syst_s, and In most states they are not
allowed to run except on tilerace track In a sanctionedrace And In
today'n racing rules, generally you could determine whether you're
going to race stock or race modlfled. If .youracn stock you're going
to have to have a syst(_ that meets the 7_ di_Alevel. If you race
modif|ed_ aml the$ are AllnvledIn s_
no control
those maehlnos_ especially
i
...........
oroasj the manufacturerhas
or that And nobody glvos A (tang AI)ouL th_ sound level on
the iluy racing or the poopln a_ tile race track.
.542
44
ErnJo Oddo
One last
question.
fltck tltlier
- International
H(lrvester
i think time point Ilere is LIlaL whether tile p,lrts
theyirn
lint labeled,
,1re labeled
at" whetlmer
has ilothin!_ to (In wl LIt _/hether $cmleonetrill
8 vollJole no matter wlmatit
tile rPA_s concern for
is,
voluntary
1 LIlinh it's
program.
Important
IIlOdJfy
,_s vie address
Could lie have Lhe'r,latrJx hack
Up on the hoard for Just a second.
| think
It_s
importnnt
to hring up at this
do hnve voIur_tary areas that
the auto and light
California
the arnn_ whore wn
First
trucks I|_ve been very staccossfully
and sor,_ other
manufacturers. It's
loc,_]lti_s
oa a voluntary
are a prohlc{:1, it's
solve that
pcnl)l_m.
of'all,
hoti_
controlled
in
hosts by the.
not new vehicles _lld _lell nlaintahmd
any of those areas thor
ellfOrCCm_nt mill
point
have been _.ccessful.
,]od|fied
vehicles
vehlclns
In
and only
Timehlhlv.Y truck you all.dad
to
Uill is a rn_tterthere nf the ICe rcgulatinn.,,_torcycles
areJ.st
about tohe
various
regulated
_tates
nnd in the henrhlgs
and so on
vehicles and aftennarkut
they
I've
attended
In time
have done a good Job of bringing
parts
Snowmobiles we have noticed,
that
Into
their
cm,I)Iiance where they are regulated.
have ,1 special
_tt.atlon
buses you no_l have your thumb on and so I guess all
as you said,
] Call see that's
there any major gain for Is motorboats al_d | u.derstand
at thnse, _lill
you're
looking
n!)l Roper
lie Just started
this year lookhlg at
I might respond a little
that
In tile early
programs f_lrly
thnse.
more to flick's
Stages on all
comnent there,
of those products
dn_lnstrnam or have alrcn(ly
look at what was going on from a voluntary
stages of the ._tudy and i'(I
<_
/
like
sot regulations
standpoint
to mention that
54J
i'd
add tho,gh,
that we have regulatory
that we dhl
In the early
in Californh_
and some
45
of these other places, automobilesand light trucks, they did bave
standardsIo effect Illthe late sixtiesor earller seventiestbat set
standardsIn a sense dld have a lot to do in bringing so_,eof the noise
levels down. I also agree that it's tilemodifiedvehicles ttlatare
a problem, That varies from categoryof vnhlcle to at er categorlos
of vehiclesellIIo_b|(7a problclnit Is, Particularlymotorcyclesseems
to be a blg proble:n,
}la,yne
H_rc.s, - HI_C
I'd llko a clarification,i got the l_presslonFrom listeningtn you
earlier Chatyou°re shootil]gfor sG_noform of conlparative
rating as
opposed to on absolute ratlog, Iam speakingof compnrlng the level
of an eftermarketexhaust system to an OEItexhaust system or comparing
an exhaust aysterltoo total vehicle noise. Is thls a misconception,
If not canyoltexplain ;Ibyyou're silootlngfor comparative?
I meant to convey timethoug!Itthat wemre lookingat both of those,
He have not decided at thls point whether one from oar standpolnt
is better than the other, bqJtwe dld want to get con_mnt and Infarction
on the kinds of thin_s
to us as tools
In
assessingthe performanceof an exhaust system by both _pproaches.
Does tl)at
answer yo_irquestion?
!la_e
Harcus
Yes
Ernle Udda
Th_nk you very fl_cll.Is there A final coal.eatyou would llke to make,
'i
l
that would be evatlable
filll,before_leclose
,
the session?
544
i
.'46
BIll
Roper
| guess from EPA's standpoint
for participating
h_ this
the EPA In the noise offlce
the tuclmical
as I think
experts
I would lJhe to again
symposium.
has conducted this
In all area rids
has been sho_m, Ill
are no easy aos_lers to s_o
Thls Is,
tllls
early
of you
the first
tlme
type of meeting filth
la a study program and
afternoon's
of the questions
thank all
I thlnh
session there really
that
we're
Faced with
att_nptlog to collect informationelland make recof;inendatlons
to the
agency. There is Jlfference of ophllon and we're not surprised
hy that, but I think Jt's teen very constructive tilelast three days
to have the caliber of people that _Ye'vehad at this meeting together
in (_tscusslngpI think guile frank|yand openlyj their opinions on this
subject and I heard a com_lentearlier this morning that even If there
were no specific reconlnendations
that came out of tiffs
meetlng, b_Jt
i
j,st the fact that a lot of ideas llerethroua up, a lot of thou[Ihts
#)avebeen discussed that SiI_Io
of the manufacturersof tl)eseproducts
i
may have plcbed up seem ideas end _temay (fatpotentlallysome noise
quietingcoming ou& of the ideas Lllatwere exchonged at Uffsmeeting.
After a11_ that's tlm busloess that we're really in Is to make it a
IltL1e quieter out there In the environmentand I thlnk that's great
If lie contributed
toward doing that
through this
meeting; so again
I_d like to thank you a11 and wish yella safe .tourneyhome wlth one
thou.qhttoo that I want to leave, and that Is that this
Is in a sense
the beginningof what I hope w111 be a continuing dialog between
_laeyof you and EPA as llelaRVafarther alon_lIllthls program,so
thank yon.
J
5451
LIST OF ATT[hDEES
ALFREDSOrl,
R. J, DR.
MonashUniversity,Uept. ofrfechanlca]Enq., ClaytonVictoria,
Australia3168
ARBIZZArII_
ROM, DIr. f.hlfF.
Eng.
MaremontCorn,,250 E. KehoeBlvd.,Carol Stream, 11],60]87
BASCOII
ROGER,Chief En,qlneer
llarley-DavIdsen,
370D Ll.Juneau,Ml]waukoe,IIIsc.5320l
[_AXA,DONALDE., Prof,
Universityof RIsconsln,432 R. Lake SI;.,
I1adlson,
IHsc.53706
BECK, Jill, Mana.qer
Sun Electric,6323 R, Avonda]e,Chlcaoo,Ill. 60631
BEcKorJ,
IIEIR,Mana,qer
Sales
DonaldsonCo., 1400 I/.,q4St,, Dloomln_iten,
l.IInnesAta
ac5431
BELLINO,ROCKY, R_Dr.lana,qer
Mr. GAsketCo,,Div. IJ.R.Grace,4566 Sprlnoo
Rd., Cleveland,Ohlo 44|31
_ERIL, MARTIr(, _lana,qerAce. Prod.
John Peere,220 E. Lake St., llorlcon,
lllsc.53032
I_LASER,
DIIIC,
III"
A,, Sr. ResearchF.n,qlneer
Cq_ResearchLAbs,C_ITeclmfcalCenter,ilarren,
MI 48090
BLASS,JAROSLAV,Res. fl.qr.
KawasaklMotor Corp.,Shal:opeo,
HInn
OORTIIWIEK,
JESSE 0., Ilotse Section Administrator
F] PeRt,oF Envlr.Regulation,2562 _ec_tive CenterCircleE.,
TalI_h_ssee,FL 32301
BOTELER,KErl,V.P,
R&I_FR_fflers,
2415 S.l'_.
14th, OklahomaCity, Ohlahoma
BRRI_ER,A, J., l)r.
RationalResearchCeuncilof Canada,IIonLreal
Road, Ottawa,Ont. KIAOSI
RREI_RArl,
KERNETII,
_n,qr.
llendrfekson
Ilf,q.,
_3001I.I.
4/th St,,Lyons, 111. 60534
BURKE,MARTIII
John I)eere,220 E. Lake St., I(orlcon,
lll_c.
53032
CAIIILL, JORrl, Salts llanaoor
Stemco (.l_',q.Co., P.O. /]ox 1909, Lon.qview, Texa_ 75601
_1
I
CIIERG,PETER,St. En,qlneer
Stemco_#9 [ndus_rlalRlvd,,Lon,qviel_,
Texas 75601
'
547
CRAGGS,TONY, Or,
University of Alberta, Edmonton, Alberta,
Canada T6G 211
CROCKER,M. J., Dr,
PurdueUnlverslty,
'Ray_#.HerricJ_
Labs, _.$.
Lafayette,hldiana4/907
PANNER, T. A., V.P. Engineering
ArvlnAuto DIv.DArvlo Ind.,Columbus,Indlana472(]I
DAVIES, PETER, Prof.
I.S.V.R.,Unlversltyof Southampton,
Southampton,EnglandS095NIJ
OIKA, ROBERT,Noise£ngineer
ChryslerCorp.,Provlnfl
Ground,Chelsea,Ill
EARNSIiAW,
GINNY,Editor
'Bureauof NatlonalAffalrs,1231 25L11S(;.,t/ashhlfltoe,
l).C.20037
EONARDS,SCOTT
EPA, Crystallflail,
#2, Room1102,I.Ia11
Code AW-471,
ArIin_ton_VA 20460
ERICKSOII,
LARRY,V,P.
Nelson Industrlos,
P.O. IIox428, StonRhton,Irlsc,535(19
GIRVAN,HICIIAEL
J., Asst. _xec,D1r.
MotqrcycIe& Hope(I
I,d. Council,802-45RichmondSt., _;.Toronto,
Ontario CanadaMSII1Z2
GOPLCN,GARY,Pev_l. Engr.
NelsonMuffler,Pox428, Stoughron,Hlsc, 53S09
GROCK, RAY, President
Pipes Etc,, ]632H. 139th,Gardona,Callf.
HALL, d_VI_SR., V.P.
A P Parts Co., 1001SplnIbushAve., Toledo,Ohlo 43G94
liftS,
T/_S
G, Noise Control En(lr.
J.I. Case Co., lO0State St. CL 124,Racine,Fllso.53404
IIARTER,
E. J., Chieffl&OEngr.
BurgessIndustrlns,'
I]urgess
Hannln.n
IJfv., {}101CarpenterPwy.,
Pallas,Texas 7524/
HENDRIX,[}AVID,
R., _)anagor
C, Cugr.
Rlley-[lea|rd
Inc,,P.O. Box31115,Shreveport,LA 71130
D
54B
_
__e¸3_
''
__ _ '_'_
'_I'_:
"i*_'_
;"•
,
r
IIERDERT_
I_RK
Unlvorsltyof ClnclnnaLl,I.lech.
Eng.,llallLoc #72, Cincinnati,
Ohio 45221
IIICKLIIIG, ROIIERT
Gelloral Iiotors Research, tlarr'nn, HI 41J070
IIORtIETT_IIARRY,SeniorEn_r.
HcI)onneil Uougl_s Aotr. Co., 5301 Rolsa Ave., II_mtinq_on [leach, CA 92647
NIAGA|.IA,HI_IEICIII
lit tsulltsht Ilotoro Co., lO-Ohkuracho, Ilakaharaku, KallasaI:t, Japan
IRVINE,GERALD,Hor. Engr,
ScorpionInc,,P.O, I]ox300, CrosbyIRI,56441
JOIINSON_
DOANE,Test Engr,
CatorplllarTractorCo., 100 II,E.Adams,Peoria, ILL 51501
KERR, dales
USEPA,tlashington,
D,C. 20460
KICINSKI,KEN, Engr.
RelsonMufflcr,Rt, 51, 5touohton,IIisc,,
.53589
KILHER,ROGER D,_ tlech,Enflr.
National6ur_auof S&andards,Dido, 233, Rom= A149,
Waslilngton,
IJ.C.20234
KOIIISIII,
K,, Director,t/ashlngton
Office
J/_IA1050 17th St,, N,I/.,ISashington,
O,C. 20035
KOPEC,JOllll,
Acoustlca]LiaisonEn_r.
I{Iverbanl¢
Ac_nstlcalLabs, 1512 DotaviaAve,, Geneva, ILL, 60134
KRALL, ERIC 6.
A 11Volvo Truck l}iv,,
Dept. 26435,A,R, 29, Gothenburg,St+eden
LAI, PATIII(:.K
K0
A.C,S,L|:d,_I14 RailsldeRoad,Toron&o,Ontario,Canada
LITTLE,ROSSA., rngr,
Calif,lliohway
Patrol,255 l.'i&
Avemm,_ Sacramento,CA 95C08
LOTZ, R, IT.
Chry_]erCorp,,'Detrnlt,
Illchloan
_ICCORIIICK,
J/VIES,
St, Engr.
Walker_tf.q.
Co., 3901 IIillls
Rd,, 6rass l.ake=filch49240
j_
IIC 00/IA611,J/VIES R.
Riker Ilfg,Inc., 4901 StlckneyAve,, Toledo,01143612
.
549
HArlfl, ROYL., Enqr.
J,I, Case, 700 State St.,
Racine, I_tsc. 5340_
HARCUS,IJAYIIE,Technical Analyst
rlotorcycle Industry Counctl, 4100 Dtrch St., Sutt_ 101
Ilewport
Oeacll,
CA 02660
I.tARGOLIS,
DOIIALD,
Prof.
Universityof Californla,D_pL. of I4.E.,Davis,CA 9561(3
IIASOII,
BOB
US IIOTITransportatlon
SystemsCenter,KnnaallSq,, CambridgeHA 02142
NILOS,JOSEPII,
Q.C._lanager
II.D.I.,
5310 If.66th St., Chicago,111.
NILLER,ILA., Staff Engr.
International
IIarvaster,
2911 Hnyer lined,ft, Ilayne,
Ind. 46003
HOLLOY,CHARLEST., Dr.
USEFA,Hashlnflton,
I}.C.
MOIII)ZYK,
DARRYLJ.
fluffler
IIynamlcs
Inc.,5310 H. 66th St., Chicago,Ill.,50630
I100rl,
51[As.L,,tlgrTest
)/hit_ liotor Corp., 35129 Curtis fllvd.,
Ea_tlake, Ohto 44094
HOORE,,IIH,Engr
John Oeere Co,, Iforlcon, Htsc. 53032
MORLEY,R, K., SupV.
fordliotorCo,, 2]500Oabtood,Dearborn,lilch48124
HORSE,IVAN E., Prof.
IInlverslty
of C1nclnnatl,r_Allkoc
72,C1ncinnatl,Ohlo 45221
HUTII,
ROY N,
International
Sn_nobI1e IndustryAssoclatlnn,
1800 tt, StreetrhH.
I/_shlngton,
0,C. 22036"
I15 DAIII,
tl,g,. Day, Engr.
Dekwoodfilvd,,
Dearborn,Ml 40120
IIAVARRE,
GEORGE,S_les Ilan_oer
Rtkerlifo,Inc,,4901 Stlcknny,Toledo, 0111043612
I_ECIIUATAL,
H ICIIAF'L
1111n01}EPA,2200 ChurchillRd., Sprlngfleld,111. 52706
l,
55O
_.'-b_L'_{_:_',;;_
- .' ':_:;
_.I_
¸.:.._
. .:._.
%_.:....
I C , "2: • ,E ",t
t
tIEHECELL,JACK,
Sales
tlgr.
Donaldson Co.,
Htnneapolts,
/1inn
t/ICROL5,
JENI
Vombardler
ResearchCenter,Valcourt,Quebec,Canada
NIEtlOELLER,
BOil,
Lab /.lena!for
Arv1nAutmlot/ve,Z505 IL SalisburySt., H. Lafayette,Ind. 4790G
NOLER,ROBERT_'.,ttanager
[laromont
Corp.,250 E. Kehoe,Carol Sired,l,
111. 60187
/IORDI£,
KEIItlETII
D., Designer
//elson t.luffIer, [lox 42B, Stoughton, _/|sc. 535_9
:
OggO, ERT/ESTT.
/Icgonne].l
DouglasAstr.,5301 DolsaAve., lluntin_Iton
Beach,CA g264/
T'
,:
OLSOI_,
OAVID A.,Sr. Researchgngr.
ReIson Industrles,P.O. flex420, Stoughten,I.llsc.,
535(|9
PAGE, II.II.,
Re_.Engr.
Intern_t|onal
Harvester,15600 CountyLlne Rd., lllnsdale,
Ill. 60521
PALAZZOLO, JOS[PIIA., Bey. Ennr.
Fordt.lotor
Co., 20500 Oakl_ood,
Penrborn,1114t3124
PARKER,ROBERT,Ac. Engr,
A M F llarley
gavldson,tllhta,kee,
I$Isc.
PETRALATI, VIC, M._.
USEPA,401 th St., S.H.,Nashlngton,D.C. 20057
PRAIPRA,NICK, ACCT. Algr.
Donaldsqn,Co., Inc.,P.O. Box 1299,tllnne_pol1$,
/llnn55440
REIIIIIART,
CHARLES,Tes|:Engr.
DonaldsonCo., Inc., P.O. llo_1299,/tfnneapoll_,
llJnn.55440
RE/fIIEK_J. tl.
Clpon Industrles,Inc.,22 Ikon St,, Keydale,Onterlo
RENZ, HILLIAH,Ct,Hgr.
i11ssan
llo_r Corp., 18501 S, FigueroaSI:.,Carson,CA 9024B
ROI]ERTS,PETER,I_R.
G1donInd., Inc., 22 IronStreet,Rexdale,Ont. /IGLS5_2
RORLEY,ELROY, PreJ.En_Ir.
FWO Corp., Clintonvllle,
lllsc.54929
|
N
_
551
ROHINGER, 0., Engr.
878 SylverAve., Englewood,C11ffs,R.J..07632
ROPER, _;fl.E., Chief STI$
USEPA,AI1471,
Std.& Reg., DIv., L.Hashlnoton,
0.C. 20460
RONCI,N.L., DirectorE×ch. Sys. Eng. A Research
llaTl',er HF_]., 3901 llillis
Road, Grass Lal_e, llIchiflan
49240
NOSA, D.A., Director Product Engr.
A P Parts Co., 543 HatzhHmr R(_ad,Toledo,Ohlo 43697
ROSS,DAVIO, Res. Er,_Ir.
Arvin Ind., 2505R. Sallshury,W. Lafayette,Ind. 47900
ROIILEY, DOUG, Ch. EnfIr.
UonAldsonCa., Inc., 1400 I/.94tliSt., _l|nneapo_l%Ilhln.
SCIIEIDT,
I_AYNE,
A., Ifgr
Itaremollt
Corp. 250 E. Kehoe Ave., CarD] Stream, I]linols60182
SCHIIEICIIEZ,
STEVE,Pr. Engr.
DonaldsonCo., Inc., 1400 ilestg4th St.,HIInneapolis,
Itlnn.
SCHULTZ, DOUG, VP Engr.
Wallcer
[.Ifg.
Co., 120] tl|ch.DIvd.,Racine,lJIsc.53402
SF.YI_EIIT,
ANOREI_,
F.,Asst. Prof;
Universityof Kentucky,Lexhlgt_n,KY 40506
(;ilAFFER,FRED, ProJ. Engr,
The Plxil)le
Co., g70 PittsburghDrive,Delaware,Ohlo 43015
SIIAUGIINESSY,
JIN, Supv.rxh. [nor.
llayes
AlbionCorD.,]999 llIldwood
Ave., Jackson,HIIch49202
SMIT#1, Inl.A., Prof.
DnlversltySo_thFlorida,Colle.ge
or Enqlneerlng,Tampa,FL Z]3620
SIIEr,ICENRERGER,
JOIINI'., Assoc. Prof.
WeSt VirginiaUnlverslI;y,
tlechanlcal
Engineering,
Ilorganto_m,
O.V. 26505
SOIDARICII,
FRANK,H.t.qr.
DonAldsonCo., Inc.,1400 N. 94th St., fJ]oomlngton,
tIInrl
5543]
SPARKS, CECIL R., Director
Sauth_vest
ResearchInst., P.O. Drmmr 2(J510,
San Antonio,Texas 10284
D
It
:m
552
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_
STEPIIEIISOtl,
DOIIALO,
Sen. Research[ngr.
OuCbonrdItarlne,P.O. fiox663, I11}_aukee,
V;isc.53201
STOCK,ARTItURVI.,Chief [ngr.
Cro_m Coach Corp.,2428 E. 12thSt., LosAnf)oles,
CA 9064G
STURTEVArJT, I). Prof.
Caltech, Pasadena, CA 9111_5
SVO[IOOA,
ED, VP Enor
ItldasInternationalCorp.D 5300FI.73rd St., D_dfordPark, 11160638
TIIOIIAS,
d. H., Vice Pres.
llarelnOnt
Corp.,250 E. KehoeBlvd.,
C.arol
Stream, 111.60187
VAN DEMARK,RALPII, Ext. Dir.
A.E.s.rI.c.,
222 Cedar Lane,Teaneck,tI.J.
D7665
WIIITN[Y,
DOllR., Exec.Emlr.
Genera|IIotors,G._I.Tech Center,Ilarren,
'llch48090
WRIGIIT,
PETER,Pres.
Gi(lonInd., Inc.,22 Irnn Street,Rexdale,Ontario
YNIAOA,_t_KOTO,Staff Eng.
ToyotoMotor Co., 1099 LlallStreet_Iest,
Lyndhurst,[l.J.C)7071
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