Nov 05, 2015
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self Propulsion Tests
Resistance & Propulsion (1)MAR 2010
Introduction
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Objectives of Self propulsion test:
1. To confirm early ship power & speed requirements and to check the propulsor is able to absorb the
delivered power
2. To derive values of propulsion factors ( )w, t, R
Test procedure
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Towed resistance (R)MotorDynamometer
T - R
T, Q
T
V
Model is mounted on the carriage similar to a
conventional calm water test. However a propulsion system
is also added
n
Test procedures
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Towed resistance (R)MotorDynamometer
T - R
T, Q
T
V
1. Number of sets of runs in each of which the model hull speed is fixed at a speed corresponding to the ship speed
VmVs
Test procedures
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Towed resistance (R)MotorDynamometer
T - R
T, Q
T
V
2. In each set the propeller speed (n) is varied from a low value (TR model over propelled).
(T = Thrust, R = Resistance)
Test procedures
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Towed resistance (R)MotorDynamometer
T - R
T, Q
T
V
3. During each run measurements are taken for
& carriage dynamometer force T - RVm, nm, Tm, Qm,
Test Procedures
Rod Sampson - School of Marine Science and Technology - 15th April 2008
For extrapolation of the results to the full scale prediction we refer to BTTP-1965 procedures as
follows:
Model test results are analysed in terms of:
KTP , KQP , C TR
Self propulsion test
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Mod
el s
elf p
ropu
lsio
n po
int
P/D = 0.8Ship service self propulsion point
Ship
sel
f pro
puls
ion
poin
t (T
rial
)
Ship
sel
f pro
puls
ion
poin
t (S
tand
ard
X=
0)
KTP
C TR
1.2 (1 + x)F C s C m
C TRC s C m
(1 + x)F C s C m
JP0
+
-
For fixed Vm
10KQP10KQPKTP
Self propulsion test
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Ship
sel
f pro
puls
ion
poin
t
Ship service self propulsion point
Ship
sel
f pro
puls
ion
poin
t (T
rial
)
Ship
sel
f pro
puls
ion
poin
t (S
tand
ard
X=
0)
KTP
KQPC TR
1.2 (1 + x)F C s C m
C TRC s C m
(1 + x)F C s C m
JP0
+
-
The residual drag coefficients ( ) of the ship and model will be the same but the frictional will not. Therefore a skin friction correction must
be applied to C TR
CR
Self propulsion test
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Ship
sel
f pro
puls
ion
poin
t
Ship service self propulsion point
Ship
sel
f pro
puls
ion
poin
t (T
rial
)
Ship
sel
f pro
puls
ion
poin
t (S
tand
ard
X=
0)
KTP
KQPC TR
1.2 (1 + x)F C s C m
C TRC s C m
JP0
+
-
(i.e. shift 0-0 line down)SFC = cs cm
The first shift corrects for the skin friction coefficient:
Self propulsion test
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Ship
sel
f pro
puls
ion
poin
t
Ship service self propulsion point
Ship
sel
f pro
puls
ion
poin
t (T
rial
)
Ship
sel
f pro
puls
ion
poin
t (S
tand
ard
X=
0)
KTP
KQPC TR
1.2 (1 + x)F C s C m
C TR
(1 + x)F C s C m
JP0
+
-
cs trial = (1 + x)f csFor trial condition the power prediction factor is also included (2nd shift)
(1 + x)f cs cm
Self propulsion test
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Ship
sel
f pro
puls
ion
poin
t
Ship service self propulsion point
Ship
sel
f pro
puls
ion
poin
t (T
rial
)
Ship
sel
f pro
puls
ion
poin
t (S
tand
ard
X=
0)
KTP
KQPC TR
1.2 (1 + x)F C s C m
C TR
JP0
+
-
1.2(1 + x)f cs cmFor service the power margin of 1.2 is included (3rd shift), hence:
Self propulsion test
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Ship
sel
f pro
puls
ion
poin
t
Ship service self propulsion point
Ship
sel
f pro
puls
ion
poin
t (T
rial
)
Ship
sel
f pro
puls
ion
poin
t (S
tand
ard
X=
0)
KTP
KQPC TR
1.2 (1 + x)F C s C m
C TRC s C m
(1 + x)F C s C m
JP0
+
-
Then at ship trial self propulsion point we read off:
Jp KQp KTp
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self propulsion test
Then model rps at the self propulsion point:
nm =V
Jp Dm
Self propulsion test
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self propulsion test
define a resistance coefficient:
kR =Rm
n2mD4m
Where is the resistance of the ship reduced to model scale and calculated
from ( )
Rm
c
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self propulsion test
Then propulsive efficiency D
D =PePD
=RmVm2pinmQm
=n2mD
4mkRVm
2pinm n2m D5mKQp
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self propulsion test
Then for each speed calculate:
PD = (1 + x)PED
D =Jp2pi
=kRKQp
Jp =Vm
nmDmFinally, given that:
(Self propulsion test)(towing tank test)
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self propulsion test
Confirmation of the propeller speed including the scale effect due to the propeller wake
(rpm)Ns = 60 nm
DmDs
Ns = k2 Nstandard
k2 = 1.265 0.1(1 + x)F 0.2CB(according to BTTP-65)
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self propulsion test
Finally plot the predicted values of PD, Ns vs Vs
PD
Ns
NsPD
PDDesign
VsPredicted trial speed
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self propulsion test
The previous method derived the ship power and speed requirements.
The following is to derive . w, t,& R
Tests require: Thrust and torque data of the stock propellers used Equivalent open water propeller curve
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self propulsion test
From the open water data of the equivalent propeller select one of 2 methods, either:
Same torque at the propulsion test rpm, this is known as Torque identity analysis
Same thrust at the propulsion test rpm, this is known as thrust identity analysis
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self propulsion test
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.1 0.2 0.3 0.4 0.5 0.6 0.65 0.7 0.8
KT 10 KQ Eta_0
Advance coefficient
Input from S-P tests for Torque identity analysis
Input from S-P tests for Thrust identity analysis
oq
ot
KQ ot
KQ p
KT oqKT ot
KT p
Jo q Jo t
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Thrust identity analysis
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.1 0.2 0.3 0.4 0.5 0.6 0.65 0.7 0.8
KT 10 KQ Eta_0
Advance coefficient
ot
KQ ot
KQ p
KT otKT p
Jo t Jp
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Thrust identity analysis
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.1 0.2 0.3 0.4 0.5 0.6 0.65 0.7 0.8
KT 10 KQ Eta_0
Advance coefficient
ot
KQ ot
KQ p
KT otKT p
Jo t Jp
ht =1 t1 wt Rt =
KqotKqp
wt =Jp Jot
Jp
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Thrust identity analysis
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.1 0.2 0.3 0.4 0.5 0.6 0.65 0.7 0.8
KT 10 KQ Eta_0
Advance coefficient
ot
KQ ot
KQ p
KT otKT p
Jo t Jp
ot =Jot2pi KtpKqot
Rod Sampson - School of Marine Science and Technology - 15th April 2008
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.1 0.2 0.3 0.4 0.5 0.6 0.65 0.7 0.8
KT 10 KQ Eta_0
Advance coefficient
oq
KQ p
KT oq KT p
Jo q
wq =Jp Joq
Jpt =
Ktp KRKtp
hq =1 t1 wq
Torque identity analysis
Rod Sampson - School of Marine Science and Technology - 15th April 2008
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.1 0.2 0.3 0.4 0.5 0.6 0.65 0.7 0.8
KT 10 KQ Eta_0
Advance coefficient
oq
KQ p
KT oq KT p
Jo q
Torque identity analysis
Rq =KtpKToq
oq =Joq2pi
KtoqKqp
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self propulsion test
In evaluation of in the thrust identity:R
o =PtoPDo
B =PtbPDb
R =Bo=PTbPDb
PDoPTo
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self propulsion test
In torque identity PDb = PDo
Rq =PTbPTo
=KtpKToq
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self propulsion test
In thrust identity PDb = PDo
PTb = PTo
Rt =PDoPD
=KqotKqp
Rod Sampson - School of Marine Science and Technology - 15th April 2008
Self propulsion test
D = hq oq Rq = ht ot Rt
But
The above check may be applied to the derived quantities for both analysis procedures which should
give similar results.
End of Presentation
Rod Sampson - School of Marine Science and Technology - 15th April 2008