anti-stall systems

UNIVERSITY OF WEST BOHEMIA
FACULTY OF MECHANICAL ENGINEERING
DEPARTMENT OF POWER SYSTEM ENGINEERING
Inovace předmětu „TEORIE PROUDOVÝCH STROJŮ “ v rámci projektu CZ.1.07/2.2.00/15.0006
JET ENGINES
COMPRESSORS
UNSTABLE WORKS
INTRODUCTION
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Unstable compressor work is phenomena,
which is happened in specific compressor
working mode. Unstable work is accompanied
by a rapid changes of pressure and velocity of
flowing media. This phenomena also causes
the decreasing middle value of pressure on
compressor outlet, vibrations of compressor
parts and intensive sound effects.
Result of unstable work are partial possibly full
compressor or turbine damage
INTRODUCTION
Fig. Evolution of parameters during compressor stall
CHARACTERISTIC
Fig. Compressor characteristic with borders of stable work
STABLE/UNSTABLE WORK
a) stable
b) stall
c) unstable work - high values of losses
Fig. Types of unstable work
STABLE/UNSTABLE WORK
φ1 – angle of tangent to profile mean
curve at rotor blade grid inlet [°]
β1 – relative velocity angle of air at rotor
blade grid inlet [°]
i – angle of attack [°]
w1 – relative velocity at rotor inlet [m.s-1]
COMPRESSOR STALL
As soon as working point starts move from design point
to lower values of mass/air flow rate at point P will starts
the phenomena of “STALL”. Basically:
Qm↓ → c1↓
→i↑ → β1↓→
→ at point P – stream secession in suction face of
profile → p2>p1 → stream starts move backward and
starts pulsate
The phenomena of “STALL” exist for every value of
RPM (n).
Curve created by P points is called SURGE/STALL
LINE!!! This line determine area of stable/unstable
work of compressor.
COMPRESSOR STALL
Q m=1 A1 c1=2 A2 c 2=konst.
2 c 2 A 1
=
1 c 1 A 2
1
2 n
 
2
p
=
1
p1
1
2 n
1
p
=C  n
p1
 
c 2 1n
C =konst.
c1
COMPRESSOR STALL
Change of πC cause change of c2/c1 ratio. High
ratio c2/c1 cause compressor STALL!!!
Change of πC cause:
●
RPM (n)
●
Total temperature before compressor (T1T )
UNSTABLE WORK
As soon as working point starts move from design
point to HIGHER values of mass/air flow rate at point
R will starts the phenomena of stream secession.
Basically:
Qm↑
→ c1↑→-i↑ → β1↑→
→ at point R – stream secession in pressure face of
profile → p2T< p1T → stream do not pulsate, but there
are HIGH LOSSES of πCT and ηCT.
With regard to engine mode, that part is irrelevant
– doesn't draw the line behind point R
LOCAL AND ROTATING STALL
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Stall area will rotate in oposite direction of rotor
blade rotating with speed v= λ-u. That speed
depends by number of rotating areas.
Rotating stall could be on whole blade or in part
of blade and could be just in one but also in
more blades.
In stator stall area will rotate in direction of rotor
blade rotating
LOCAL AND ROTATING STALL
Fig. Rotating stall
LOCAL AND ROTATING STALL
Fig. Types of rotating stall
ANTI-STALL SYSTEMS
Fig. Bleed valve anti stall system
ANTI-STALL SYSTEMS
Fig. Bleed valve and bleed belt anti stall systems
ANTI-STALL SYSTEMS
Fig. Bleed valve anti stall systems TV2-117(Mi-8)
ANTI-STALL SYSTEMS
Fig. Bleed valve anti stall system – TV3-117 engine
ANTI-STALL SYSTEMS
Fig. Compressor characteristic after using bleed valve anti
stall system
ANTI-STALL SYSTEMS
Fig. Vortex ring anti stall system – principle of work
ANTI-STALL SYSTEMS
Fig. Vortex ring anti stall system – principle of work
ANTI-STALL SYSTEMS
Fig. Vortex ring anti stall system
ANTI-STALL SYSTEMS
Fig. Vortex ring anti stall system – RD-33 (MIG-29)
ANTI-STALL SYSTEMS
Fig. Vortex ring anti stall system – R-29 (MIG-23)
ANTI-STALL SYSTEMS
Fig. Variable vanes anti stall system – principle of work
ANTI-STALL SYSTEMS
Fig. Variable vanes anti stall system
ANTI-STALL SYSTEMS
Fig. Variable vanes anti stall system TV3-117 (Mi-24)
ANTI-STALL SYSTEMS
LPK
HPK
Fig. Dual-spool anti stall system
ANTI-STALL SYSTEMS
Fig. Dual-spool anti stall system – principle of work
ANTI-STALL SYSTEMS
Fig. Dual-spool anti stall system
REFERENCES
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Otis, Vosbury: Aircraft gas turbine powerplants
– Jeppesen: 2002
Rolls royce – The jet engine, 1996
Hanus D., Maršálek J, : Studijní modul 15,
Turbínový motor, CERM, s.r.o. Brno 2004
Kadrnožka J.: Tepelné turbíny a
turbokompresory, CERM, s.r.o. Brno 2004
DISCUSSION...
...QUESTIONS