Hydrodynamic Aspects of Steerable Thrusters

Transcription

Hydrodynamic Aspects of Steerable Thrusters
Jie Dang & Hans Laheij
Wärtsilä Propulsion Netherlands BV (WPNL), 30-09-2004
Dynamic Positioning Conference, Houston, USA
© Wärtsilä
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Contents
z Introduction
J. Dang
z Thruster configurations
J. Dang
z Propulsion Efficiency
J. Dang
Bollard pull efficiency
Free sailing efficiency
Pulling or pushing arrangement?
z Matching with the engine / E-motor
J. Dang
z Interactions
H. Laheij
Thruster water jet
Thruster-thruster interactions
Thruster-hull interactions
z LIPS® HR high efficiency nozzle
H. Laheij
z Applications for DP / DT vessels
H. Laheij
z Conclusions
H. Laheij
© Wärtsilä
2
Introduction
z Developments
New ideas, new concepts, new products
- everyday
Diesel-electrical drive and large AC E-motors - stimulating
Consequence:

More possibilities
More suitable system for certain operation
More confusing
-positive
-positive
-negative
z Guidelines
Review of the development
General guideline
-van Terwisga
(2001)
-Deter (1997)
z Restricting our discussion in:

© Wärtsilä
Azimuth thrusters with propellers
FP, CP, Ducted, Counter-rotating Propellers
Not including – water jet, pump jet, Voith Schneider
Not including – Cavitation, noise, maneuvering, etc.
3
Thruster configurations (1)
LIPS® Z-drive thruster with an open
CP propeller
© Wärtsilä
LIPS® L-drive thruster with a FP
propeller in LIPS® HR nozzle
4
Thruster configurations (2)
Thruster with Z-drive and CRP
installation
LIPS® Z-drive thruster with open
propeller (CPP) and pulling
arrangement
© Wärtsilä
5
1.2
Kt, 10Kq, Eta0
z Open water
characteristics
Kt, 10Kq, Eta0
Propulsion efficiency (1)
Kt
10Kq
Eta0
1
1.2
1
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0
0
0.2
0.4
0.6
0.8
1
Kt
10Kq
Eta0
0
1.2
0
0.2
0.4
0.6
0.8
1
a typical open propeller
Kt, 10Kq, Eta0
1.2
J=V/nD
J=V/nD
typical counter-rotating propellers
Kt, 10Kq, Eta0
1.2
Kt
10Kq
Eta0
Ktn
1
0.8
Kt
10Kq
Eta0
Ktn
1
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0
0
0.2
0.4
0.6
0.8
1
J=V/nD
a typical nozzle propeller in 19A nozzle
© Wärtsilä
1.2
6
0
0
0.2
0.4
0.6
0.8
1
J=V/nD
a typical nozzle propeller in LIPS® HR
high efficiency nozzle
z Slope of curves
dKT
sT =
dJ
and
sQ =
d (10 K Q )
dJ
z Counter-rotating propellers
sT CRP > sT OP
and
sQ CRP > sQ OP
z Ducted propeller
sQ nozzle _ propeller
© Wärtsilä
J =0
=0
7
z Bollard pull efficiency
Merit coefficient
( KT / π )
ηd =
KQ
3
2
Merit coefficient ηd
1.9
1.7
1.5
1.3
1.1
0.9
B4-70
Wageningen CRP series
Ka4-70 in 19A nozzle
Ka4-70 in HR nozzle
0.7
Comparison of bollard pull efficiency among
different type of propulsors
© Wärtsilä
0.5
0.5
8
0.7
0.9
1.1
1.3
1.5
propeller pitch ratio (front propeller for CRP) P/D
z Bollard pull efficiency
Ducted propeller (major influences):
Blade contour
Pitch distribution
Trailing edge
1.9
1.7
1.5
2.0
1.3
1.8
1.6
1.1
1.4
1.2
0.9
1.0
0.7
0.8
B4-70 in 19A nozzle
0.6
0.9
1.0
1.1
1.2
Ptip / P0.7R
Influence of tip loading on pull efficiency (propellers
with Kaplan form blades in No. 19 nozzle, based on the
model test results of van Manen, 1962)
© Wärtsilä
9
1.3
0.5
0.5
0.7
0.9
1.1
1.3
1.5
propeller pitch ratio P/D
Influence of tip chord length on pull
efficiency
70
engine power [%]
pull thrust [tons]
60
50
120%
100%
Engine output limit
80%
40
60%
30
40%
20
blades with normal anti-sing edge
on suction side
10
20%
blades with large ''anti-sing
edge'' on pressure side
blades with large ''anti-sing edge'' on
pressure side
0%
50%
0
0%
50%
100%
150%
engine power [%]
60% 70%
80% 90% 100% 110%
engine shaft speed [%]
Full scale measured power-shaft speed relation for
the same propeller with different ‘anti-sing edges’
Full-scale measurements of pull thrust vs. shaft
power for a tug boat – Thetis, Iskes Sleepdiensten
BV, IJmuiden, the Netherlands
© Wärtsilä
blades with normal anti-sing
edge on suction side
10
8 Kt
Ct =
π J2
JKT
η0 =
2π K Q
Open water efficiencyη0
z Free sailing efficiency
0.8
Open Propeller B4-70
P/D=
Wageningen CRP series
1.2
Ka4-70 in high efficient nozzle
0.7
1.0 1.0
1.3
0.8
1.1
1.2
0.6
1.0
0.5
0.4
0.0
© Wärtsilä
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Thrust load coefficient Ct
Comparison of the open water efficiency of different propulsors (where P/D is either
the pitch ratio of the propeller or the pitch ratio of the front propeller for counterrotating propellers)
11
z Pulling or pushing arrangement?
z Efficiency of pulling arrangement

Two factors
Friction losses – underwater housing in the slipstream of the
propeller wake
2. Rotational energy recovery – due to the down stream strut and
fins
1.

For propeller with light load

Rotational energy recovery > Friction losses
pulling is better
fast vessel

For propeller with heavy load

Friction losses > Rotational energy recovery
pushing is better
low speed vessel
© Wärtsilä
12
z Based on systematic research
at SVA Potsdam
© Wärtsilä
Grey area Ct=0.5 to 1.0
13
z Pulling or pushing arrangement?
z Wake field differences
A typical wake field at propeller disc for the pushing arrangement
with one strut for a twin-screw vessel
© Wärtsilä
14
A typical wake field at propeller disc for the pulling arrangement
of a twin-screw vessel
120%
FSAH FPP OPEN
z Fixed pitch propeller
or controllable pitch
propeller
FSAH CRP
BAH FPP OPEN
BAH FPP HR
Max. BAH thrust (366kN) at Max. torque
BAH CRP
100%
90%
80%
FSAH FPP HR
110%
Matching with the engine/E-motor (1)
MCR
Design Point
power PB [%]
70%
60%
50%
40%
30%
Comparison of three different propulsion
concepts for an offshore supply vessel with
diesel-electric drive propulsion systems (two
azimuth thrusters per ship at the stern), here
FSAH - free sailing ahead, BAH – bollard
ahead
20%
10%
0%
0%
10%
20%
30%
40%
50%
60%
70%
shaft speed N [%]
© Wärtsilä
15
80%
90%
100%
110%
120%
Matching with the engine/E-motor (2)
z A typical semi-submersible
PB[%]
160%
Trial-(bow)Thuster
Trial-(stern)Thuster
Service-(bow)Thruster
140%
Service-(stern)Thruster
Bollard Vs=0kn
Bollard Vs=-2kn
120%
MCR
100%
80%
Qmax
60%
40%
The typical propeller curves for a semi-submersible
with two pontoons and four azimuth thrusters with
FPP in LIPS® HR nozzle, two thrusters at the bow and
two at the stern
20%
0%
50%
60%
70%
80%
90%
100%
110%
120%
N[%]
© Wärtsilä
16
Thruster-thruster, thruster-hull interactions
understanding the jet (1)
z water jet of the thruster - the shape
© Wärtsilä
17
z water jet of the thruster - the position of the maximum speed
Shape of jet of water behind
a working thruster at zero
speed (bollard condition)
Line of
maximum speed
D
Line of zero
speed
© Wärtsilä
18
z water jet of the thruster - the maximum speed
Maximum jet speeds for
thruster in bollard pull
condition
© Wärtsilä
19
z Maximum speed for water jet close to a flat plate
Position of maximum
speed does not stay
on center line, but
moves towards the
plate
Position of maximum
speed goes to shaft
center line at x/D = 4
(was 6 without plate)
Flat plate at 0.75D below
thruster center line
Magnitude of maximum speed does not change compared to
open water situation !
© Wärtsilä
20
thruster-thruster interaction (1)
z 3 major different interactions in discussion
D
D
x
D
x
φ
x
© Wärtsilä
21
z Thrusters in tandem in free
open water
z Formula to calculate thrust
ratio
T / T0 = 1 − 0.8
2
( x / D)3
Thrust ratio [%] .
100%
80%
60%
40%
Lehn(1980)
Moberg(1983)
20%
D
x
0%
0
© Wärtsilä
22
5
10
15
20
25
30
Propeller distance ratio x/D
z Thrusters in tandem under
a flat bottom
z Formula to calculate thrust
ratio
2
( x / D)3
T / T0 = 1 − 0.75
Thrust ratio [%] .
100%
80%
60%
40%
Nienhuis(1992)
D
Blaurock (1977)
20%
x
0%
0
© Wärtsilä
23
5
10
15
20
25
30
.
Thrust ratio [%]
z Steering angle on the
thrusters can reduce the
thrustloss
z Larger angles reduce
thrustloss
z Formula to calculate the
thrustratio
100%
90%
80%
70%
60%
50%
40%
tφ = t + (1 − t )
φ3
30%
130 / t 3 + φ 3
20%
Nienhuis (1992) x/D=2.0
Lehn (1980) x/D=3.0
Lehn (1980) x/D=6.0
10%
0%
0
D
φ
10
15
20
25
30
steering angle of the forward thruster [degrees]
x
© Wärtsilä
5
24
35
100%
Total thrust ratio of two thrusters [%] .
z Interaction applicable to
both bollard and free sailing
condition
z Important since DP
thrusters are used for main
propulsion as well
80%
60%
40%
Blaurock (1977) J=0.00
20%
0%
0
© Wärtsilä
25
5
10
15
20
25
30
Thruster-hull interaction (1)
z Water jet close to a flat plate
z Reductions can be as high as 20-25%,
z Thrusters in the bow are inefficient in the sailing
direction
© Wärtsilä
26
Thruster-hull interaction (2)
z water jet along curved surface
© Wärtsilä
27
thruster-hull interaction (3)
z Coanda effect
© Wärtsilä
28
Thruster-hull interactions (4)
thrust deduction t
z Thrust deduction depending on
stern heeling angle
z For astern thrust in practice
two times larger than ahead
Slope
0.12
0.11
0.1
0.09
0.08
0.07
0.06
0.05
0.04
0.03
10
12
14
16
18
20
22
24
stern heeling angle [degrees]
© Wärtsilä
29
thruster-hull interaction (5)
z Typical results of Thruster-hull interaction test
0
345
100%
15
90%
330
30
80%
315
45
70%
60%
300
60
50%
40%
30%
285
75
20%
10%
0%
270
90
255
105
240
120
225
135
210
150
195
165
180
© Wärtsilä
30
LIPS® HR Nozzle
introduction - different nozzles (1)
z Working principle of nozzle propellers
Flow induced pressure
difference creates positive
thrust
© Wärtsilä
31
LIPS® HR Nozzle
z Different nozzles
© Wärtsilä
32
LIPS® HR Nozzle
z Different flow patterns at BAH and FSAH
Free sailing
(FSAH)
Bollard condition
(BAH)
© Wärtsilä
33
LIPS® HR Nozzle
background of HR nozzle
z Designed to improve the flow
around the nozzle
z Designed to improve
efficiency at high speed
z Series tests done at German
SVA Potsdam institute
z Improved performance; 8 to
10% better than 19A
Flow visualisation in cavitation tunnel
© Wärtsilä
34
LIPS® HR Nozzle
flow analysis - CFD (1)
z Propeller in HR nozzle - StarCD®
© Wärtsilä
35
LIPS® HR Nozzle
z Comparison - 19A versus HR nozzle
VELOCITY
FIELD
19A Nozzle
© Wärtsilä
HR Nozzle
36
LIPS® HR Nozzle
z Calculated flow pattern around HR nozzle
rounded leading and trailing edge
larger induced velocity
more nozzle thrust and less resistance
© Wärtsilä
37
LIPS® HR Nozzle
z Comparison - calculated bollard pull thrust
Bollard condition
19A
120%
100%
HR
108%
103%
100%
100%
80%
60%
40%
20%
0%
Model scale
© Wärtsilä
Full scale
38
LIPS® HR Nozzle
Full scale
Difference
model to full
scale
Model scale
© Wärtsilä
39
LIPS® HR Nozzle
full scale experience
Many HR-nozzles already sailing !
With:
z CPP’s
z FPP’s (4 and 5 bladed)
z Steerable thrusters
Up to 3.75 [m]
Up to 5500 kW
z Ranging from 0 to 18+ knots
z Dmax. = 5.2 [m] with 12640 kW
© Wärtsilä
40
Application of Thrusters
z The largest pipe layer Solitaire
z Vessel spec
Length
Transit speed
Accommodation
300
13
420
[m]
[kn]
[men]
z Thrusters

© Wärtsilä
8 LIPS® azimuth thrusters
partly bollard pull and partly free sailing design
partly HR and partly special nozzle
5.55MW@199RPM
propeller diameter 3.75m
41
z Heavy-lifting vessel - Thialf
z Vessel spec

Length
Breadth
Accommodation
201
88.4
736
[m]
[m]
[men]
z Thrusters

© Wärtsilä
6 LIPS® azimuth retractable thrusters
bollard pull design (85 tons/unit)
19A nozzle
5.5MW@199RPM
42
z Maintenance Service Support
Accommodation Unit
z vessel spec
Length
Breadth
~94
~45
[m]
[m]
z thrusters

4 LIPS® azimuth thrusters
bollard pull design (50 tons/unit)
LIPS® HR nozzle
2.5MW @ 203RPM
Overspeed of driving motor for free sailing
© Wärtsilä
43
z Largest Semi Submersible Heavy Lift
Vessel

Blue Marlin
2 x Retractable thrusters with HR Nozzle
Propeller diameter 3.4 m
2 x 4500 kW
Main propulsion upgraded with HR Nozzle
Propeller diameter 5.2 m
1 x 12640 kW
Resulting in more than 30% increase in bollard
thrust
Carrying largest offshore structures in the world
© Wärtsilä
44
z Cable Ship

CS Atlantic Guardian
P=2 X 2200 kW
Propellerdiameter 2.5 m
Electric drive CPP thruster
L-drive configuration
Able to absorb full power at
all conditions
© Wärtsilä
45
z Cable Layer

© Wärtsilä
46
CS- Knight
Main propulsion 2 X 4500 kW
Retractable 2 x 2000 kW
Electric driven FP propellers
z Anchor Handling Tug Supply Vessel

© Wärtsilä
Seabulk Badamyar
P= 2 X 1440 kW
7.4% extra bollard pull due to HR Nozzle
Bollard pull is 10% over charter requirements
47
Conclusions
Hydrodynamic aspects of steerable thrusters
z Mission profile determines the choice of the design point; off-design
condition and its co-operation with the E-motor (or engine) are
important
z For low-medium speed applications (e.g. DP/DT) pushing propellers
are more efficient than pulling propellers
z Interactions among thrusters, hull, barge, etc should not be ignored
in thruster design
z High efficiency nozzles improve efficiency

8% extra bollard pull thrust
10% extra free sailing propulsion efficiency
Propulsion Supplier should take all hydrodynamic aspects
of thrusters into account to ensure a perfect match
between thrusters and the vessel
© Wärtsilä
48
Questions?
Wärtsilä Propulsion Netherlands BV
Jie Dang
[email protected]
+31 416 388283
Hans Laheij
[email protected]
+31 416 388546
© Wärtsilä

Hydrodynamic Aspects of Steerable Thrusters

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