The Specialist Committee on Azimuthing Podded Propulsion ... · PDF fileThe Specialist...

The Specialist Committee on Azimuthing Podded PropulsionReport and Recommendations

LIFTINTSTRUTBODYPOD RRRRR Δ+Δ+Δ+Δ=Δ

RBODY = 1+ kBODY( ) 12

CFρV 2S⎛ ⎝ ⎜

⎞ ⎠ ⎟

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.0E+00 5.0E+05 1.0E+06 1.5E+06 2.0E+06 2.5E+06

Rn_L

Cf

Noriyuki Sasaki , National Maritime Research Institute

Ir. Jaap H. Allema. Maritime Research Institute

Netherlands

(MARIN), Wageningen, The Netherlands.

Professor Mehmet Atlar. (Former Chairman)

University of Newcastle, Newcastle-upon-Tyne, United Kingdom.

Dr. Se-Eun Kim. Samsung Heavy Industries Co. Ltd., Daejeon, Korea.

Dr.Valery Borusevich. Krylov

Shipbuilding Research Institute

(KSRI), St. Petersburg, Russia.

Dr. Antonio Sanchez-Caja. VTT

Industrial Systems, Espoo, Finland.

Dr. Francesco Salvatore. Istituto

Nazionale

per Studied Esperienze

di

Architettura

Navale

(INSEAN), Roma,

Professor Chen-Jun Yang (Secretary). Shanghai Jiao Tong University (SJTU), Shanghai, China.

Dr. Noriyuki Sasaki (Chairman). National Maritime Research Institute

(NMRI),

Tokyo, Japan.

Membership

Outline

1.

General

2.

Questionnaires

3.

Review and update Procedure 7.5-02-03-01.3

4.

Cavitation behaviour of podded propulsors with steering angles

5.

Hydrodynamics of POD propulsion for ice applications

6.

Technical Conclusions

1. General

Meetings(1) Tokyo, Japan, March 2006.

(2) Brest, France, Octover

2006, in conjunction with the 2nd T-Pod Conference

(3) St. Petersburg, Russia,

June 2007

(4) Shanghai, China, March 2008.

Tokyo(NMRI)

St. Petersburg(KSRI)

1.

Review and update Procedure 7.5-02-03-01.3

“Propulsion, Performance-

Podded Propulsor Tests and Extrapolation”. Give special emphasis on how to scale housing drag and to the validation of full-scale propulsion prediction.

2.

Continue the review of hydrodynamics of POD propulsion for special applications

including fast ships, ice going ships (Liaise with the Ice committee) and special POD arrangements like Contra-rotating Propellers (CRP) and

hybrids. Include the practical application of computational methods to prediction and scaling.

3.

Review and analyse the cavitation behaviour

of podded propulsors. Emphasize high pod angles

and normal steering angles including dynamic behaviour. Include the practical application of computational methods to prediction and scaling.

Committee’s Tasks

Task DistributionsTASKS MA NS JA AS SEK FS CJY VB Kawanami Kume Ohhashi

Type of Instruments ○ ○ ◎ ○ ○ ○ ○ ○Unit Thrust Mes. ○ ○ ◎ ○ ○ ○ ○ ○Prop. Thrust Mes. ○ ○ ◎ ○ ○ ○ ○ ○Prop. Torque Mes. ○ ○ ◎ ○ ○ ○ ○ ○Idle Thrust Mes. ○ ○ ◎ ○ ○ ○ ○ ○Idle Torque Mes. ○ ○ ◎ ○ ○ ○ ○ ○Gap Effect ◎ ○ ○ ○SFC at SPT ◎ ○ ○ ○Driving System ◎ ○ ○ ○Air Draw ◎ ○ ○ ○DATA Prosessing ◎ ○ ○ ○Ｏｔｈｅｒｓ ○ ○ ○ ○Propeller Base ◎Unit Base ◎Unit Thrust Correction ◎ ○Wake Scaling ◎ ○Sea Trial ○ ◎ ○ ○ ○ ○ ○Monitoring ○ ◎ ○ ○ ○ ○ ○Hybrid CRP ○ ◎Crash Stop ◎ ○Ice ◎ ○Crabbing ◎ ○Sea Keeping ◎ ○Others ○Simulation of R.T ◎ ○ ○ ○Simulation of S.P.T. ◎ ○ ○ ○Simulation of Full Scale ◎ ○ ○ ○Maneuvering ◎ ○ ○ ○Sea Keeping ◎ ○ ○ ○Others ○ ○ ○ ○

CFD Application

Powering

Model　Ｔｅｓｔ　Procedure

Ｓｃａｌｉｎｇ　Ｂａｓｅ

Special Theme

History of Podded Propulsion

FANTASY

ELATION

Uikku

cruise ship

ice breaker

TEMPERA

2002

1995

1991

Queen Mary II

double acting tanker

2005

2002

1993

electric propulsion

HAMANASUTRITON

HATAKAZE

submarine, war ships, ice breaker, cruise ships

DAS

SESFAST POD

Combined pod and waterjet setup, Atlar et al (2006)

The hybrid system is composed of two steerable (wing) pod drives and two fixed (central) – booster – flush type water jets

Contra-rotating Pod Propellers

2 shafts – 2 electrical motors

Slender shaped pod

Super Eco Ship Project

Pure CRP Pods (Mechanical Drive) on the Shiga Maru

Shige Maru is one of the ships delivered as “Super Eco Ship”. The Super Eco Ship project was led by Ministry of Land, Infrastructure and Transport and National Maritime Research Institute from 2001.

Pump jet pod (PJP) unit ,Bellevre et al. (2006).

A comprehensive numerical and experimental design study was conducted for 2 cruise liner type pod units (13MW) for a 45000 GRT cruise liner using 2D-3D RANS codes. Based upon this comparative study it was concluded that the propulsive performance of PJP was 14% higher than the conventional tractor pod mainly due to its superior open water efficiency.

2. Questionnaires

We sent following questionnaire to 40 organizations and received 20 replies.

25th ITTC Specialist Committee onAzimuthing Podded Propulsion

Questionnaire on Model Test Procedure, Powering Method and CFD Computation Method for Podded Propulsion System

Introduction The task assigned by the 25th ITTC to this specialist committee is to develop and validate practical experimental and numerical prediction procedures for full scale performance of Azimuthing podded Propulsion System. As a first step toward accomplishing the task, the committee developed the following questionnaire to assess current practices in use by various organizations, including the ITTC member organizations. The analysis of the responses to the questionnaire will be presented to the 26th ITTC conference as part of the final report of this specialist committee. The questionnaire consists of six(6) parts: (A) Propeller Open Water Test, (B) Podded Propeller Open Water Test, (C) Resistance & Self Propulsion Test, (D) Powering, (E) CFD application (F) Special theme. You do not have to complete all the sections or questions of the questionnaire. If you are not in a position to answer the questionnaire at all, then a null response would be appreciated. If that is the case, please fill in the Respondent’s Information only and return. Please return the completed form preferably before 25th/Sept./2006. for the committee to evaluate the results in time. If you fail to meet the deadline please try to return anyway at your suitable time. Respondent’s Information (Example)

Name: Noriyuki Sasaki_______________________ Organization: National Maritime Research Institute Position: Group Leader of Propulsors Research Group Mailing Address: , Shinkawa, Mitaka-shi, Tokyo 181-0004 JAPAN_____________________________ Tel. No.: +81 422 41 3505______________________ Fax No.: +81-422 41 3053____________________ E-Mail Address: [email protected]______________ Website: http://www.nmri.go.jp/

Nation OrganazationCN SJTUCN DUTFI VTTIT INSEANJP NMRIJP IHIMUJP MHIJP SHIMEJP ASMBKR SSMBKR MOERIKR HMRINL MARINUK UNCLUK Quinetic

GER HSVAPOL CTOSW SSPACA IOTCA MU

Questions A series : Propeller Open Water Test for Pod Propulsion

A-1 What kind of experimental tank do you use? A. Towing Tank B. Circulation Water Channel (incl. Cavitation Tunnel) C. Both D. Others

102

40

ABCD

Towing Tank

A-7 What is the standard Reynolds Number (based on Dp)for the open water test? A. We don’t have any standard for it B. We have a standard Reynolds Number C. We have two standards

4

9

1

ABC

We have standard Rn = ******

Experimental tank

Questions A series : Propeller Open Water Test for Pod Propulsion

A-3 What is the diameter of propeller?

0

100

200

300

400

500

600

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Dp

[mm

]

A-11 How much is the propeller immersion, Im?

0

50

100

150

200

250

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Im/D

p [%

]Diameter

immersion

Survey Results of Gap Width

Questions B series : Pod Propeller Open Water Test

B-3 What is the propeller gap between boss and pod housing?

0

1

2

3

4

5

6

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Wid

th o

f G

ap [

mm

]

Survey Results on Propeller Immersion

Questions B series : Pod Propeller Open Water Test

B-11 How much is the propeller immersion, Im?

0

50

100

150

200

250

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Im/D

p [%

]

C-1 How do you analyze self-propulsion test?

A. Conventional way (regards pod housing as an appendage) B. Unit base (regards pod unit as the propulsor) C. Both

2

11

6

ABC

Survey Results on Propulsion Analysis Methods for Pod Propulsion Ships

Questions C series : Pod Propeller Self Propulsion Test

regards pod unit as a propulsor

propulsor

appendage

Survey Results on Rn Correction Method

D-1 Do you assess the effect of Reynolds numbers onperformance of Podded propulsor? A. Yes B. No

14

5

AB

Questions D series : Powering to full scale

D-1 If yes, what kind of correction method do you use for podhousing drag correction(s)?A. EmpiricalB. Semi-empiricalC. CFD-baseD. Others( )

1

73

3

ABCD

We assess the effect of Reynolds numbers

3. Review and update

Procedure 7.5-02-03-01.3

Flow diagram for full scale power prediction from model test results of a vessel equipped with podded propulsion.

Pod unit open watertest


Pod housing drag correction


PoweringIn full scalePowering

In full scaleSelf propulsion testSelf propulsion test

Resistance testResistance test

Propeller open water test


High Rn

Low Rn

Covering Area of Guideline

Letter from ABB to ITTC (24th)

ABB Round Robin Tests

+NMRI +SSMB

Problems to be solved

• Very few official data of full scale

• Each model basin developed their own procedure

• Pod maker complains about this chaotic condition

Test Scheme

ABB

Model Basin

model propeller

Pod Drawing

Test Menu

Pod Resistance Test

manufacture Pod Model

Propeller Open Water Test

Pod Unit Open Water Test

Full Scale Prediction










High Rn

Low Rn


Propeller open water test.

Propeller open water test.

The procedure for open water tests of the propellers for a ship equipped with podded propulsors is basically the same as that of Procedure 7.5-02-03-02.1" Propeller open water tests", (ITTC, 2002b) although some typical aspects for propellers with strongly tapered hubs are not considered and these aspects are given in this section where necessary.

7.5o

Aft fairing Forward cap

Hub

Cylindrical Hub Tapered Hub

Hub

Tapered Hub

Propeller Open Water Wfficiency

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

0.1 0.2 0.3 0.4 0.5 0.6

Kt/J**2

ηo(P

rop.

Eff

icie

ncy)

Propeller Open Water Efficiency with the Same Model Propeller

12%

working point

Main reasons: Reynolds number,Shaft Immersion, Boss Correction ?

mean (except top and bottom)=0.653










High Rn

Low Rn


Pod unit open water test.

Principal dimensions of pod housing used in round robin testing programme,

Veikonheimo (2006)

Principal dimensions of Pod Propulsor

Length of Pod Body 0.4563 m

Diameter of Pod Body 0.1135 m

Height of Strut 0.1372 m

Chord Length of Strut 0.2672 m

Total Wetted Surface Area of Pod 0.2129 m2

manufactured by Model Basin

Typical pod unit open water test setup

supplied by ABB

test scheme

pod housing: manufactured according the same drawing supplied

model propeller: supplied

propeller cap and dummy boss : supplied

Typical pod unit open water test setup

ITTC Recommendation

The propeller shaft must be immersed at a minimum depth of 1.5 propeller diameters (1.5D), preferably 2D. It must also be emphasized that the top of the strut should also be well submerged during the test.

Propeller gap during experiments

Shaft housing: stream lined fairing

End plate: to prevents vertical flow

Strut gap: as small as possible

Wedge: to prevent an uneven strut gap Propeller gap: 2-3 mm

Pod unit open water test results with the same model

Pod Open Water Wfficiency

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

0.1 0.2 0.3 0.4 0.5 0.6

Kt/J**2

ηo(P

od.

Eff

icie

ncy)

15%

mean (except top and bottom)=0.620


0

5

10

15

20

25

30

2 2.5 3 3.5 4

V(m/s)

Tp,

Tunit,R

pod(

kgf)

Tp

Tunit

Rpod

NMRI(red) is very close to orange however, components are different


Comparison between POWT and Pod Unit OWT

POD unit efficiency(Model) is lower than Propeller Open Water Efficiency

0.58

0.59

0.6

0.61

0.62

0.63

0.64

0.65

0.66

0.67

0.68

0.58 0.59 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 0.68

Propeller Open Water Efficiency

Pod O

pen W

ater

Eff

icie

ncy

Central zone





Powering /full scalePowering /full scaleSelf propulsion testSelf propulsion test




High Rn

Low Rn


Pod Housing Drag Correction

A summary of existing semi-empirical correction methods for pod housing drag (24th ITTC)

Establishment HSVA MARIN SSPA SUMITOM O

Number of calculation zones 3(4) 3 3 3

Frictional Resistance

calculation method

Schoenherr ITTC1957

ITTC1957

ITTC1957

Pressure Resistance calculation No （form

factor） form factors form factors

Strut-

pod body interaction No No Yes Yes

Inflow velocity components Axial only Axial only Axial only Axial only


LIFTINTSTRUTBODYPOD RRRRR Δ+Δ+Δ+Δ=Δ


• There is no unique method to match existing model basins

( see the test results obtained by ABB round robin test)

• Total balance of system accuracy is most important

• The system should not be too complicated

• The system should be examined by several means incl. CFD

Where, BBODY , RSTRUT , RINT and RLIFT are components of the resistance

associated with pod body (nacelle), strut, pod body-strut interference and lift effect due to swirling flow action of the propeller, respectively.

Pod Housing Drag Correction (RBODY )

RBODY = 1+ kBODY( ) 12

CFρV 2S⎛ ⎝ ⎜

⎞ ⎠ ⎟

kBODY =1.5 DL

⎛ ⎝ ⎜

⎞ ⎠ ⎟

32

+ 7 DL

⎛ ⎝ ⎜

⎞ ⎠ ⎟

3

Where,S = Wetted surface Area (m2)L = Pod length (m)D = Pod diameter (m)

Pod Housing Drag Correction (RSTRUT )

RSTRUT = 1+ kSTRUT( ) 12

CFρV 2S⎛ ⎝ ⎜

⎞ ⎠ ⎟

( )4602 ssSTRUTk δδ +=

Where, is the average thickness ratio of the strut and S is wetted surface area of the strut.

Sδ

Pod Housing Drag Correction (RINT )

Where, troot

is maximum thickness at strut root and Croot

is chord length at the same section. CROUND

is correction factor for various fairing and it varies from 0.6 to 1.0.

RINT =12

ρV 2t 2 f troot

Croot

⎛

⎝ ⎜

⎞

⎠ ⎟

f troot

Croot

⎛

⎝ ⎜

⎞

⎠ ⎟ = CROUND 17 troot

Croot

⎛

⎝ ⎜

⎞

⎠ ⎟

2

− 0.05⎛

⎝ ⎜ ⎜

⎞

⎠ ⎟ ⎟


6.3.3 Effect of propeller slip streamThere are two expressions to predict the axial inflow velocity which is

accelerated by a propeller given by Mewis (2001) and Holtrop (2001), respectively, as below:

Where, VA

and n are the advance speed of propeller and propeller shaft speed respectively, P is the average pitch of the propeller blades and

CT

is thrust coefficient defined by:

Where,T = Propeller thrust AP = Propeller disc area

VINFLOW = VA 1+ CT( )0.5

AINFLOW VanPaV )1()( −+=

CT =T

0.5ρVA2AP










High Rn

Low Rn


Pod Resistance test(additional)

Pod resistance test

Pod resistance tests

199.0

350.0

360.0

三分力計

3KW ACモータ

モータ固定台

ポッド延長筒

波よけストラットその1

波よけストラットその2

三分力計固定治具

高速艇用抵抗計測装置

ポッド固定治具&検力部

波よけの側面板

波よけの上面板

波よけの下面板

波よけの正面板

組み立て図（側面）

Investigate Reynolds Effect on Pod Resistance

Pod Resistance test (V=6m/s) at NMRI

Comparison of the pod housing drag from predictions and test results from seven different model basin. Veikonheimo (2006)

0.000

5.000

10.000

15.000

20.000

25.000

30.000

35.000

40.000

45.000

50.000

0 1 2 3 4 5 6 7 8

Present Method(Turbulent)

Pod Advance Speed (m/s)

Pod

Uni

t Res

ista

nce

(N)

Present Method(Laminar/Transition)

POD OWT

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

5.0E+05 1.0E+06 1.5E+06 2.0E+06 2.5E+06 3.0E+06

Cd

Comparison of pod resistance coefficients (CD) for the pod housing measured by seven model basins, Veikonheimo (2006).

frictional resistance coefficients

no T.S with T.S

Comparative analysis of pod housing drag predicted by the present and other methods

V= MODEL SCALE3.25 m/s

Rpod(N) R_body(N) R_strut(N)R_btmfin(NRint_strut(NRint_bfin(N)ITTC 9.13 3.38 2.99 0.58 2.03 0.16A 8.18 3.34 2.99 0.60 1.14 0.11B 5.27 2.66 2.26 0.35C 6.45 2.37 1.64 0.27 2.03 0.16EXPmin. 8.17EXPmax 13.38

Rpod R_body R_strut R_btmfin Rint_strut Rint_bfinITTC 6.4% 2.4% 2.1% 0.4% 1.4% 0.1%A 5.7% 2.3% 2.1% 0.4% 0.8% 0.1%B 3.7% 1.9% 1.6% 0.2% 0.0% 0.0%C 4.5% 1.7% 1.1% 0.2% 1.4% 0.1%

V= FULL SCALE11.83 m/s

Rpod(KN)R_body(KNR_strut(KN)R_btmfin(KNRint_strut(KNRint_bfin(KNITTC 44.63 13.16 11.24 1.99 16.94 1.30A 46.76 13.01 11.25 2.06 18.60 1.84B 20.04 10.17 8.34 1.52 0.00 0.00C 34.97 14.14 11.24 1.99 7.06 0.54

Rpod R_body R_strut R_btmfin Rint_strut Rint_bfinITTC 3.8% 1.1% 1.0% 0.2% 1.5% 0.1%A 4.0% 1.1% 1.0% 0.2% 1.6% 0.2%B 1.7% 0.9% 0.7% 0.1% 0.0% 0.0%C 3.0% 1.2% 1.0% 0.2% 0.6% 0.0%

percentage to Tunit

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

ITTC A B C Exp(mean)

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

ITTC A B C Exp(mean)

?

model scale

full scale

Comparison of results from direct CFD and ITTC simplified method on pod housing drag calculations

DirectCFD ITTC simplified procedure

Blades 100.0% 100.0%

Strut+ uppermost body -4.6% -2.7%

Pod body -2.9% -2.9%

Fin -0.2% -0.5%

TOTAL(unit thrust) 92.4% 93.9%

This means that Pod open water efficiency is less than propeller open water efficiency by 6-8% at model scale

0.58

0.59

0.6

0.61

0.62

0.63

0.64

0.65

0.66

0.67

0.68

0.58 0.59 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 0.68


Pod

Open

Wat

er

Eff

icie

ncy

Central zone

0.58

0.59

0.6

0.61

0.62

0.63

0.64

0.65

0.66

0.67

0.68

0.58 0.59 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 0.68


Pod

Open

Wat

er

Eff

icie

ncy

Central zone

present method

CFD

Comparison of results from direct CFD and ITTC simplified method on pod housing drag calculations (model scale)

present method

CFD

Full Scale Prediction based on own procedure

Veikonheimo(2006)

Effect of using different scaling method with their own test data on full scale power


0.58

0.59

0.6

0.61

0.62

0.63

0.64

0.65

0.66

0.67

0.68

0.58 0.59 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 0.68

Pod O

pen W

ater

Eff

icie

ncy

Model scale >>>>> Full scale

ITTC

0.54

0.56

0.58

0.6

0.62

0.64

0.66

0.68

0.7

POT(model) POD OWT(model)l POD OWT(Full Scale)

Effect of using different scaling method with their own test data on full scale power

summarypresent method

Effi

cien

cy a

t wor

king

poi

nt










High Rn

Low Rn


Self Propulsion Test.

Conclusions of pod housing drag correction method

•

The most serious problem is a scatter of obtained model test data

•

It seems that model basins have their own practical methods

•Present method can be used when tests are conducted according to ITTC recommended procedure or similar

4. Cavitation behaviour of podded propulsors with steering angles

(incl. dynamic behaviour)

Review of the experimental investigations

Pustoshny, A. V. and Kaprantsev, S. V., 2001, “Azipod

propeller blade cavitation observations during ship manoeuvring”, 4th

Int. Symposium on Cavitation (CAV’2001), Pasadena, USAWang, D., Atlar, M. and Paterson, I., 2003, “Cavitation Observations, Hull Pressures and Noise Measurements with the OPTIPOD Supply Ship in Cavitation Tunnel”, Newcastle University Report, MT-2003-003. Heinke, H.J., 2004, “Investigation about the Forces and Moments at Podded Drives”, T-POD, 14-16 April, University of Newcastle, UK, p. 305-320Stettler, J.W., 2004, “Steady and Unsteady Dynamics of an Azimuthing Podded Propulsor Related to Vehicle Maneuvring”, PhD Dissertation, Massachusetts Institute of Technology. Friesch, J., 2004, “Cavitation and Vibration Investigations For Podded Drives”, T-POD, 14-16 April, University of Newcastle, UK, p. 387-399.

Sasaki.N. (2005) “

Chapter 7 Podded Propulsion System”

JTTC 5th Propeller symposium, Tokyo,JapanStettler, J.W., Hover, F.S., and Triantafyllou, M.S., 2005, “Investigating the Steady and Unsteady Maneuvering

Dynamics of an Azimuthing Podded Propulsor”, Trans. SNAME, p. 122-148Bretschneider, H. and Koop, K.-H., 2005,“Cavitation Tests with Design Propellers for the FASTPOD Ropax

Vessel”, HSVA Report, K 17/04. Johannsen, C. and Koop K-H., 2006, “Cavitation Tests for Two Fast Ferries with Pod-Drives Carried out in HSVA’s

Large Cavitation Tunnel HYKAT”, 2nd

T-POD Conference, Session 5, 3-5 October, University of Brest, France. Allenstrom, B. and Rosendhal, T., “Experience From Testing of Pod Units in SSPA’s

Large Cavitation Tunnel”, 2nd

T-

POD Conference, Session 5, 3-5 October, University of Brest, France. Islam, M.F., Veitch, B., Akinturk, A., Bose, N. and Liu, P., 2007b, “Performance characteristics of a Podded Propulsor During Dynamics Azimthing”, 8th

CMHSC, St John’s, Canada

Effect of Toe angle on hull pressures, Friesch (2004)

Effect of steering angle on hull fluctuating pressures, Johannsen & Koop (2006)

Effect of steering angle on blade cavitation,

Bretschneider & Koop (2005)

FASTPOD Container ship Pod arrangement,

Allenstrom and Rosendhal (2006)

Effect of flap angle on the cavitation inception and unit thrust

Efficiency loss

Comparison of propeller forces and moments at fixed (continuous line) and dynamically controlled pod angles

(scattered points) Heinke (2004).

-6

-5

-4

-3

-2

-1

0

1

2

3

0 30 60 90 120 150 180 210 240 270 300 330 360

ψ [°]

KT

X, K

TY [-

]

KTY

KTX

KTX

KTY

Sway force when pod undergoing a fast ramp change in azimuth angle from 0°

to 60°, Stettler

et al (2005)

Longitudinal thrust coefficient on pod unit in static and dynamic azimuthing conditions, Islam et al (2007b)

Comparison of predicted propeller thrust with experiments in steering conditions, Sasaki (2005)

Jδ

= V * cosδ/nD = J0 * cosδ ….apparent JJ's = Jδ

+ ⊿J …….. displacement effect by pod housing⊿J = = C1 * J0 * |δ| (C1 =const. 0.3-0.5)

FN

stem

δ

Tp

T

u

Xu

Yu

Du

KTP

two operations

Jδ

⊿J0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

-100 -50 0 50 100

δ(deg.)

Ktp

J=0.9cal

J=0.9exp

C1 =0.35

J0

Pod unit OWT(δ=0 deg.)

Review of the numerical investigations

Krasilnikov, V., Ponkratov, D., Achkinadze, A. and Jia

Ying, S., 2006, “Possibilities of a Viscous/Potential Coupled Method to Study Scale Effects on Open-Water Characteristics of Podded Propulsors, 2nd T-POD Conference, Session 7, 3-5 October, University of Brest, France.

Deniset, F., Laurens, J.-M. and Romon, S., 2006, “Computation of the fluctuation pressure Distribution on the Pod Strut”,

2nd T-POD Conference, Session 7, 3-5 October, University of Brest, France.He M., Veitch

B., Bose N., Bruce C. and Liu P., 2006, “Numerical Simulations of a Propeller Wake Impacting on a Strut”, CFD Journal, Vol. 15, No 1, April, p. 79-85.

Kinnas, S.A., 2006, “Prediction of Performance and Design of Propulsors –

Recent Advances and Applications”, 2nd T-POD

Conference, Opening Session, 3-5 October, University of Brest, France. Guo, C-Y,Yang, C-J and Ma, N., 2008, “CFD Simulation For a Puller Type Podded Propulsor Operating at Helm Angles”, Private Communications with the 25th ITTC Specialist Committee for Azimuthing Podded Propulsion.

Funeno, I.：”Hydrodynamic Development and Propeller Design Method of Azimuthing Podded Propulsion System”, 9th Symposium on Practical Design of Ships and Other Floating Structures (PRADS2004) , Volume 2,pp.888-893(2004)

Model pod unit, Guo et al (2008)

Comparison of computed and measured forces at helm angle of 45°

CT 0.94 1.18 2.33

KT

/KT0

Exp. 1.812 1.765 1.556

CFD 1.761 1.601 1.346

KQ

/KQ0

Exp. 1.711 1.665 1.463

CFD 1.465 1.424 1.252

KL

/KT0

Exp. 0.403 0.366 0.211

CFD 0.567 0.455 0.298

Pressure distribution and propeller shaft forces in oblique flow, Funeno, 2004

Hydrodynamics of POD propulsion for ice applications

Double Acting Tanker

Full Astern 12kts

Loading comparison Sampson, et al. (2006b)

300

500

700

900

1100

1300

0.0E+00 2.0E-03 4.0E-03 6.0E-03 8.0E-03Time (s)

TH(N) Open Water sigma=24

TH(N) blockage sigma=24

TH(N) blockage sigma=8

the effect of cavitation during propulsor ice interaction

Time Series Thrust loading Data

Ice trials of Cargo Container Ship ‘Norilsky Nickel’,Wilkman(2007)

MV Norilskiy

Nickel has been designed to transport mining products from Dudinka

(Yenisey

River) to the market (Murmansk) independently without icebreaker support. The vessel is equipped with diesel electric propulsion with one 13MW podded

azimuth thruster

(Azipod).The design of the vessel follows the principles of Aker Arctic’s Double Acting Ship Concept, were the vessel is designed to be run ahead and astern in somewhat different conditions. Norilskiy

Nickel has been designed to operate in level ice and pack ice to run both ahead and astern. In heavy ridges the vessel is designed to operate mainly running astern.

MV Norilsk Nickel, Icebreaking capabilityComparison in level ice, Ahead/Astern, P = 13 MW

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

4,5

5,0

5,5

0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70 0,80 0,90 1,00 1,10 1,20 1,30 1,40 1,50 1,60 1,70 1,80 1,90 2,00

Ice thickness (m)

Ship

spe

ed (m

/s)

AsternAheadPoly. (Ahead)Poly. (Astern)

Ice trials of Cargo Container Ship ‘Norilsky Nickel’,Wilkman(2007)

Voyage Route

Astern

Ahead

5. Technical Conclusions

Technical Conclusions

(1) Procedure of pod tests and extrapolation are established however, full scale data to evaluate this method will be needed.

(2) A lot of complex system of pod propulsion such as CRP type and a hybrid type has appeared and they are not deeply studied so far because of lack of full scale data of such kinds of pod systems.

(3) A pod performance at off design condition or manoeuvring condition is so important to affect on not only cavitation and vibration but also fuel consumption. There are many papers mentioned above cavitation and vibrations at pod steering conditions however, it is also important to design the pod from propulsive performance view point taking an efficiency loss at smaller helm angle (less than 10deg.).

(4) CFD becomes very strong tool now to evaluate the scale effect of pod housing drag and extrapolation method.

Thank you for your attention

(

a

)

Smooth Aft Fairing

(b) Knuckled Aft Fairing

(c) ABB Cap

Fig. 1 Tested Caps and Aft Fairings

NMRI M.P. No.

Diameter DP [m] 0 .2310

Boss Ratio xB 0 .2975

Pitch Ratio p=H/DP 1.166

Expanded Area Ratio aE 0.669

Number of Blade Z 5Turn ing Direction Right

631

Table 1 Principal Dimension of tested Propeller Model

Propeller Cap and Aft Fairing

supplied by ABB

B-6 Where is the location of the dynamometer for thrust and torquemeasurements for propeller? A. Inside of the pod B. Outside of the pod C. Both cases

16

1

3

ABC

Questions B series : Pod Propeller Open Water TestB-9 Do you develop strategies for prevention of air drawing? A. Yes B. No

7

10

AB

Survey Results on CFD Application

E-1 What is the purpose of your CFD application topodded propulsor or to ships with podded propulsor?

A. Scaling B Propulsor design C Propulsor-hull optimization D. Other

7

79

7

ABCD

Questions E series : CFD Application

E-2 What kind of turbulence model do you introduce into yourcomputational code?

A. Baldwin-Lomax B. k-εtype or similar C. Spalart-Allmaras or similar 1-eq. D. LES ( iso or aniso ) E. DNS F. Potential Theory G. Other

2

9

300

3

4

ABCDEFG

Shaft housing and end plate

Strut gap and wedge

Propeller gap during experiments

Podded Propulsor Open Water Test

Problematic issues: Propeller-pod housing gap effect

• First reported by (Mewis 2001) and only influences propeller thrust• Limited other studies reported in supporting (e.g. Holtrop & Rijsbergen

2004) and in conflicting nature (e.g. Ukon et al 2003)

0.10.20.30.40.50.60.70.8

0 0.5 1Advance Coefficient, J

ηo -

Prop

elle

r

1.2 mm gap2.2 mm gap3.2 mm gap4.2 mm gap

Fig 4: Open water characteristics of a puller- type pod based on thrust for different propeller gap widths

(Holtrop & Rijsbergen 2004)

Podded propulsor in open water test setup

Pod Open Water CharacteristicsJ =Va/nD

KtumKq

m

POD Open water testTu, Tp, Q, n

Full Scale CorrectionK ts = K tum + ΔK t

K q = K qtm + ΔK q

K tus = K ts + ΔK tu

POD resist ance

testRpodm

Resistance Test w/o PODVm,F n ,Rn, R tm, trim,sinkage

Full scale prediction(Based on ITTC 1957 line)

Cts=(S S +S BK )/S S )*[1+K]C fs +ΔC f]+C w +C AA

Cf = 0.075/(10logRn -2) 2

ΔCf=[105*(k s /L)1/3 -0.64]10 -3CAA =0.001*A T /S S

Analysis of resistance test(Based on ITTC 1978 Cf

line)Cf = 0.075/(10logRn -2) 2

K : based on Prohaska �fs methodCw= Ctm -(1+K)Cfm

Self Propulsion Factorsw tm = 1 -Jtm *D/V m

t = (T um +R a -Rtm )/T um

ηr = K qtm /K qm

Self Propulsion Test with PODVm, F n , R a , T um , Q m ,

n, trim, sinkage

Full Scale Predictionns = (1 -w ts )*0.5144Vs/(J TS D)K tsu = Kts

+ ΔTu/( ρD 4 ns 2 )η o = K tus /K qts *J ts /2π

PDS (DHP) = 2 πρ D 5 nsK Qts /ηR 10 -6

Full scale correctionΔTu = R podm α 3 - R pod

2.3.2 Test conditionsAfter a resistance test of ship without a pod unit (same as a conventional propeller case), it is

recommended that for ships fitted with podded propulsors, self-propulsion tests should be conducted with both the ship speed and the propulsor load varied independently. In addition to Skin Friction Correction of the hull surface, load correction due to pod housing drag correction() should be considered.

TUKΔ

2.3.3 Test set upThe self-propulsion test should preferably be

carried out in the following manner: · The pod propellers are to be driven from the top

of the unit by an electric motor, through a belt drive or a geared set of a horizontal and a

vertical shafts.

· Thrust and torque of the propeller are to be measured close to the propeller. Alternatively the electrical motor could be located inside the pod for direct driving provided that the testing facility has such device available.

· The unit thrust is to be measured by means of an at least 2 component measuring frame at the intersection of the pod strut with the ship model, on which frame the motor is fitted.

Questions D series : Powering to full scale

D-2 Do you take account wake scaling effect into powering?

A. Yes B. No

14

5

AB

D-2(a) Number of data sampled. A. None B. below 5 C. between 6 and 10 D. above 11

7

5

1 1

ABCD

Survey results on tested data of pod propulsor stored

None

Principal dimensions of pod housing used in co-operative testing programme, Veikonheimo (2006)

Principal dimensions of Pod Propulsor

Length of Pod Body 0.4563 m

Diameter of Pod Body 0.1135 m

Height of Strut 0.1372 m

Chord Length of Strut 0.2672 m

Total Wetted Surface Area of Pod 0.2129 m2

a drawing supplied by ABB

Main data for the CFD study case

Model scale Full scale

Propeller diameter 0.231 5.8

Propeller revolutions(rps) 16 2.33

Advance coefficient 0.88 0.88

Reynolds number (model) 1.29x⋅106 1.14⋅108

How to use ITTC recommended procedure for powering

Tunit(90N)Rpod=Tp-Tunit

10N

Tp(100N)

Calculation by ITTC method

Tunit(88N) 12N

Tp(100N)

Pod OWT based on ITTC procedure

Tunit(93KN) 7KN

Tp(100KN)

Tunit(94KN)Rpod=Tp-Tunit

6KN

Tp(100KN)

Full scale Full scale

INTSTRUTBODYPOD RRRR Δ+Δ+Δ=Δ

TUTPMTUTU KKKK Δ+Δ+= )(

42DnRK POD

TU ρΔ

=Δ

INTSTRUTBODYPOD RRRR ++=

Comparison of computed and measured forces at helm angle of 15°

CT 1 2 4 6 10

KT

/KT0

Exp. 1.084 1.075 1.050 1.029 1.012

CFD 1.109 1.079 1.055 1.038 1.022

KQ

/KQ0

Exp. 1.155 1.128 1.075 1.040 1.020

CFD 1.065 1.042 1.029 1.024 1.019

KL

/KT0

Exp. 0.115 0.074 0.062 0.050 0.020

CFD 0.180 0.122 0.078 0.061 0.045

NMRI M.P. No.

Diameter DP [m] 0.2310

Boss Ratio xB 0.2975

Pitch Ratio p=H/DP 1.166

Expanded Area Ratio aE 0 .669

Number of Blade Z 5Turning Direction Right

631

Table 1 Principal Dimension of tested Propeller Model

Propeller Cap and Aft Fairing

supplied by ABB

Comparison of predicted propeller thrust with experiments in steering conditions, Sasaki (2005)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

-100 -50 0 50 100

δ(deg.)

Ktp

J=0.3cal

J=0.3exp

0.1

0.2

0.3

0.4

0.5

0.6

0.7

-100 -50 0 50 100

δ(deg.)

Ktp

J=0.6cal

J=0.6exp

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

-100 -50 0 50 100

δ(deg.)

Ktp

J=0.9cal

J=0.9exp-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

-100 -50 0 50 100

δ(deg.)

Ktp

J=1.2cal

J=1.2exp

C1=0.35

Evaluation by CFD approach

Tunit Rpod Ratio(Rpod/Tunit)Model scale(present) N 139.6 11.4 8.1%

Full Scale(CFD) KN 1165.0 94.8 8.1%Full Scale(present) KN 1165.0 75.8 6.5%

Ratio (presnt/CFD) 79.9%

Pressure distributions and streamlines on pod housing/strut surfaces at model and full scale Sanchez-Caja, et al. (2003)

How to use ITTC recommended procedure for powering

Pod Open Water Test

Pod Open Water Characteristics (model)

Self Propulsion Test Pod Open Water Characteristics (Ship)

Self Propulsion Factors

Powering

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