Full scale measurements on training ship SEIUN-MARU

TECHNIScHE tHIIVERSITEIT Full Scale Measurements on Training Ship

toum,r

Se iun-Maru"

_{Scheepshydrmh}

Archef

Mekelweg 2, 2628 CD D&ft Hajime Takahashi* _{Tot: O15-7esa73.Fa:O15,73}

1. Introduction

SR183 Research Panel** of the Shipbuilding Research Association of Japan which deals with a study on propellers and stern hull forms aiming at reducing

the stern vibration and noise, started on a three-year scheme in April 1980. As putting a conclusion to study on propeller***, full scale measure-ments on the training ship "Seiun_Maru"**** were performed in 1982.

At present stage, main topics on screw propeller cavitation are related to the problems on erosion and extreme increase of fluctuating pressures in-duced by unsteady cavitation. The erosion problem has been investigated for some time. On the other hand, a study on the relationship between unsteady cavitation and stern vibration is rather new, as pointed out by F. M.

Lewis and J. E. Kerwin in the paper [1], that is, "It was not until 1970 [2] that attention was given to the influence of transient propeller cavitation on vibratory excitation". Moreover, the attention is paid to the noise problem again for some reasons recently.

: -cse cf Pull Scale Measurements

The purposes of full scale measurements are firstly to measure the cavity volume and secondly to investigate the effectiveness of a highly skewed pro-peller for reducing stern hull vibration.

The information on cavity volume is essential to making progresses in the theoretical calculation of fluctuating pressures around a stern. In

order to measure a cavity volume, the laser beam system developed for measur-ing the cavity thickness distribution on propeller models [3], [4] were

modified and applied to full scale measurements [5].

The role of the full scale measurements as a part of the whole project is shown in Fig. 1.

* _{Ship Research Institute, Ministry of Transport} ** _{Prof. Takao Inui}

: Chairman of SR183 Research Panel

*** _{Prof. Hiroharu Kato Head of the No.2 Sub-Research Panel dealing with}

propellers

Dr. Hajime Takahashi Head of the No.4 Sub-Research Panel dealing with full scale measurement

3. Full Scale Measurements

Principal dimensions and a side view of "Seiun Maru't which belongs to the Institute for Sea Training, Ministry of Transport, are shown in Table i and Fig. 2. respectively. Principal dimensions of propellers (conventional

.ro-peller and highly skewed ropeller) and photographs of propeller models are shown in Table 2 and Fig. 3. In design of the propeller, the shape of a

blade section was changed from MAU type to SRIB type [6].

Full scale measurements were performed at midnights on l4thl6th May 1982 in the case of CP and on 7th'9th December 1982 in the case of HSP I

3.1 Measuring Items

Ship speed, No. of revolutIon of propeller, Thrust, Torque, Cavi-tation extent, Cavity thickness, Fluctuating pressures around the stern, Cavitation noise, Stress on blades, Hull vibration, Noise in Cabin.

This paper mainly describes cavity volume, fluctuating pressures and cavitation noise.

3.2 Measuring System

The system structure for cavitation observation and cavity.thickness

measurements is shown inFig..4 and the principle of cavity thickness

measurements is shown in Fig. 5. In the case of cavity thickness

measurements, two spots of Laser beams from Emitters 1 and 2 are

adjusted to be on a single point D in the cavitation free condition. When cavitation occurs, the spot D seperates into two spots E and F. Two spots E and F observed by TV camera are shown in Fig. 6. Cavity thickness can then be obtained by

where a factor b is determined from the geometrical locations of the

emitters and a TV camera [5].

Arrangements of pressure gauges and hydrophones are shown in Figs. 7 and 8. The measured noise signals were mainly analyzed by 1/3-Octave

Band Frequency Analyser in the frequency range from 2 Hz up to 10 KHz.

3.3 Test Results

3.3.1 Cavitation Pattern

Tip vortex cavitation occurred at 78 rpm on CP and at 92 rpm on HSP L . Sheet cavitation was dominant on both propellers. Tip vortex

cavitation on ES? Iwas thicker than that on CF.

Cavitation extent on both propellers are shown in Fig. 9. No

detrimental cavitation was observed.

3)

3.3.2 Cavity Thickness

at 163 rpm

Cavity thickness distribution on HSP lt at 0=40° is _{shown in Fig.}

10. _{Cavitation near the leading edge is thin and stable. Only few}

data of cavity thickness on CP were obtained because of damage of the measuring system due to rough sea.

3.3.3 Fluctuating Pressures

Fluctuating pressures at point C just above the propeller is

dis-cussed.

Kp5(cavitation)

I

Kp5(càvitation free) 2.5 for CP Kp5(cavitation) / Kp5(cavitation free) 2. for HSP lt

where Kp5

= 2D2 at Blade Frequency.

The results of Fourier analysis on fluctuating pressures are shown in Fig. il. _{50%'.-70% reduction in fluctuating pressures was achieved} by adopting HSP lt

3.3.4 Noise Measurements

Test results on noise measurements at 163 rpm are shown in Fig.

12. In a range of lOOHz--'5KBz, noise of HSP lt is smaller by 23 dB.

Significant differences exist at 1st3rd components of B. F., which

means that the adoption of HSP lt is quite effective in reducing fluctuating pressures, but has little effect in the audible range.

4. Model Tests

Model tests were carried out in order to estimate stern vibration and

noise of the actual ship. Therefore, to confirm the accuracy of experimental estimation, it is very important that comparison of model and full scale measurements is performed carefully. Results of model tests are also used

for the evaluation of theoretical calculation.

The measurements of fluctuating pressures induced by cavitating propellers were performed behind the complete ship model in the large cavitation tunnel

of SRI. Cavitation noise was measured behind wire mesh °ns in the cai,i-tation tunnel of the University of Tokyo.

Scale ratio of the ship model to the actual ship is 1/16.29. Diameter of the peopeller model is 0.221m. Test conditions are shown in Table 4.

Measuring points Angular Position, Radial Position, Chordwise Position, O

nR

x/C = = 30°, 0.85, 0.25, 400, 500, 60° 0.90, 0.95 0.50, 0.75

The estimated wake distribution of the actual ship was realized by using

the complete ship model and the flow liner [7] developed for removing wall effect on model wake distribution in the cavitation tunnel [8]. The wake distribution thus realized is shown in Fig. 13.

4.1 Cavitation Pattern

Cavitation patterns on the propeller models are compared with those on

the actual propeller in Figs. 14 and 15, which show that the agreement is very good. Quite similar results were obtained in the case of wire mesh

method.

4.2 Cavity Thickness Distribution

Test results measured by the laser scattering technique [4) are shown

in Figs. 10 and 16. Scale of ordinate is five times of abscissa. According

to Fig. 10, the correspondence of the model and the actual ship is rather

good. It may be said that cavity thickness distribution on an actual propeller

is estimated pretty well from model data. Variations of cavity volume esti-mated from the measured cavity thickness distribution are shown in Fig. 17

including full scale measurements. The agreement of the cavity volume at

---ec_ CSLS_U Le ¿_.C...e... ,

4.3 Fluctuating Pressure

The distributions of fluctuating pressures both in the transverse and longitudinal directions are shown in Figs. 18 and 19 together with results

of full scale measurements.

Kp5 for HSP Ewas reduced by 50-70% from that for CP. This reduction rare is considerably higher than: the reduction rate of cavity volume.

The agreement between model and full scale measurements is rather good. Tnis fact means that fluctuating pressures on a full scale can be predicted

quantitaively to some extent from model test results. 4.4 Cavitation Noise

The measured results behind wire mesh screen are shown in Figs. 20 and

21 together with results of full scale measurements.

In Fig. 20, the results for CP are compared with those for HSP E There is no difference at ist B. F. component but noise level of RS? E is lower by 5-7 dB at 2nd and 3rd B. F. component.

The comparison of the measured full scale data and the estimated full

scale data based on model test results is shown in Fig. 21. The Levkovskii method[9] is used as a scale correction. There is a trend that the estated

values are slightly higher than the measured values. It is considered that

5. Concluding Remarks

Summary of conclusions is as follows.

For example, fluctuating pressures at blade frequency at Point C in 163 rpm are

(1) (2) (2)7(1)

5)

effectiveness in adopting highly skewed propellers can be estimated by model

tests.

Reduction rate of fluctuating pressures in adopting skewed propellers are shown roughly in Fig. 22.

Future tasks concerned are firstly to establish a theory for calculating pressures and cavity volumes precisely by using the data above mentioned and secondly to make measurement of full scale wake distributions.

Future tasks ori che measurement oî cavity thickness on a actual snip are described in ref. [5].

The author is pleased to acknowledge the considerable assistance of cf th follcwin institutes.

Univ. of Tokyo, Osaka Univ., Kyushu Univ., Institute for Sea Training, Nippon Kaiji Kyokai, Mitsui Engineering & Shipbuilding Co., Ltd.,

Ishikawaja-Harima Heavy Industries Co., Ltd., Nippon Kokan K. K., Sumitomo Heav Industires, Ltd., Hitachi Zosen Corp., Kawasaki Heavy Industrìes Ltd., Mitsubishi Heavy Industires, Ltd., Kobe Steel, Ltd., Nakashirna Propeller

Co. Ltd.

CP(kg/m2) HSP E (kg/rn2)

full scale measurements 550 170 0.31

model tests 600 280 0.47

BIBLIOGRAPHY

Lewis, F. M. and Kerwin, J. E. "Vibratory Forces on a Simulated Hull Surface Produced by Transient Propeller Cavitation", Journal of Ship Research, Vol.22, No.2, June (1978).

Takahashi, H. and Ueda, T. : "An Experimental Investigation into the

Effect of Cavitation on Fluctuating Pressures around a Narine Propeller", Papers of Ship Research Institute, No.33, March (1970), or "Study on Vibratory Forces induced by a Narine Propeller - 2nd Report -", the 12th Autumn Meeting of Ship Research Institute, (1968).

Ukon, Y. and Kurobe, Y. : "Measurement of Cavity Thickness Distribution

on Marine Propellers by Laser Scattering Technique", Report of Ship Research Institute, Vol.19, No.1, Jan. (1982) or Ukon, Y. and Kurobe,

Y. : "Measurement of Cavity Thickness Distribution on Marine Propellers

by Laser Scattering Technique", Proc. of 16th ITTC, Vol.2, Leningrad,

(1981)

Ukon, Y., et al, : "Pressure Fluctuations Induced by Cavity Volume on

Highly Skewed Propellers for aRo!Ro ShiD,Report of SRI, Vol.19, No.3. (1982)

Kodaraa, Y., Takel, Y. and Kakugawa, A. : "Measurement of Cavity Thickness

on a Full Scale Ship Using Lasers and a TV Camera", Papers of Ship

Re-:--'--, Nc.:, Lec: C1983).

Kadoi, H. "On the Development of the SRI-B Propellers", Report of SRI, Vol.21, No.5 (to be published in November 1984).

Kurobe, Y., et al. : "Measurement of Cavity Volume and Pressure

Fluctu-ations on a Model of the Training Ship "SEIUN-MARU" with Reference to Full Scale Measurement",Report of SRI, Vol.20, No.6 (1983)

Kodama, Y. : "Reduction of Wall Effect Using Flow Liners in the No.2

Working Section (Ship Node? Section) of the Large Cavitation Tunnel", Technical Memorandum of Ship Propulsion Division, No.17, Ship Research

Institute. Aug. (1982)

Levkovskii, V. L. : "Modelling of Cavitation Noise", Soviet physics

Table 3 Test Conditions

Theoretical Calculation 3

Measurenent of Wake Distribution behind Ship Wodel in Towing Tank

Estimation of Wake Distribution on a Ship

'1

, Estimation of Cavity Extent and Volume

Evaluation of Fluctuating Ptessures

1ode1 Test I

'i,

Heproduction of Estimated Wake Distribution

behind a Ship in Cavitation Tunnel

'J,

Simulation of Flow Field

around Cavitating Propeller and Stern Hull

easurement of Cavity Extent and Cavity Volune eanurement of Fluctuating Presstes

t Full Scale Test i

Geometric Infonsation and Working Condition of Propeller

Measurenent of Cavity Extent and Cavity Volume Measuresent of Fluctuating Pressures

Fig. 1 Role of Full Scale Measurements

Table 4 Test Condition5 _{on Models}

Propeller N(rpm) _KT CP 149 0.200

366

MP No.218 163 0.207

306

171 0.219 2.78 HSP 149 0.195 3,57 MP No.220 163 0.201 2.99 171 0.212 2.71

N (UM) PS V (KTS) Sea State

149 2,810 14.5 C? 163 3,700 15.5 MODERATE 170 4,280 16.3 149 2,600 15.1. HSP 163 3,300 16.3 SLIGHT 171 4,000 16.6

Table 1 Principal Dimensions of "Seiun-Maru"

Table 2 _{Principal Dimensions of}

Propellers

7)

LENGTH b.p. 105.00 M Type C? HSPT

BREADTH 16.00 M Dia, of Prop. () 3600

DEPTH 8,00 M Pitch Ratio (Mean) 0.950 0.920

DRAFT 5.80 M _{Exp. Area Ratio 0.650}

0.700

CB

DISPLACEMENT

0.576

5,781.3 TON Boss Ratio 0.1972

MAIN ENGINE: DIESEL 5,40OPS.l76 RPM No. of Blades (z) 5

Blade Thickness Ratio 0.0442 0.0496

Mean Blade Width Ratio 0.2465 0.2739

Ske., Angle (deg.) 10.5 45.0

Rake Angle (deg.) 6.0 -3.03

Blade Section MAU Modified SRI-B

J) COLOR TV CAMERA STROBO _{r CAMEPA}51W EMITTER I L1 EMITTER 2

Fig. 5 Principle of Cavity Thickness Measurement Fig. 2 'Seiun-Maru" j) 1jPRESET COUNTER LFU ROTATION PULSE DETECTOR VTR

i

II - -- -

.

__:-

;-T -

FiZL=--________ j___/ t ...

-

.. .a .

(..

.4,-=- =_i___g

-CP(M.P.NO.218) HSP E (N.P.No.220) Fig.3 Propeller Models

AOM OOULATORS ARGON LESER i OPTICAL FiRS LESER 2 .GLE CONTROLLE L.E INDICATOR J TV VIDE; MEMORY J STROBOIi

POWER STRORO CDITROLLER j

SOURCE j SIGNAL CONDITIONER VIDEO CHARACTER S ENE RA TO R VIDEO TIMER MONITOR TV

Fig. 4 System Structure for Cavitation Observation

Cavity _{Emitter 1}

r \j

Fig. 6 Two Laser Spots on Propeller Blade (HSP lt ), 163rpm,

O=4O,

(O.95R, O.75c)

1L1

-. t ' t

Pore o co SC mm 720 540 reo 720 720 Fore

-

F _Starboord rl,

_{r y}

A 8 C O E -C_SO ±0_50

Fig. 7 _{Location of Pressure Gauges}

y

Fig. 8 Location of Hydrophones

K 163 RPM mm 100 Unit; ois r/P = 0.95

1234567

_{frame No.} marks

o---- measured by Laser(shp) measured bi Laser(rnodel) MC TE ECO 1000mm e 21Q Hvdroohcne

c

Fig. 10 Cavity thickness at 163rpm (HSP IL ) CP o=350' 20 0 0=30e e = 40 e = 60° 0=70° HSP :11 0=100

9)

Fig. 9 Cavitation Patterns at 163rpm I00 rIP 0.90 0=50° Icor T MC

r

SC : r/P 0.15

r/R055 Ist

163 RPM

2nd

Fig. 11 Amplitute of Fluctuating Pressures at Point C

Starboard

C2/

_\

l\I)

/\

e '

/\

\

.

LI /

/

¡

7 ( ¡

,. Nq\j}7\

\

Fig. 13 Realised Wake Distribution of the Actual Ship

3rd ¿p 530 o LE HIGHLY SIKEWED V.-ist 171 RPM MC e s SHIP MODEL MODEL

:2

___J i I TE LE MC lE

Fig. 16 Measured Cavity Thickness (RSP E )

2 5 10 20 53 20 1 2k 5k 10k 20k

;

.

+

lxB.F. 3x5.F.

Fig. 12 Noise Measurement on Actual Propllers

e

/ \

e 20

Fig. 14 Cavitation Patterns on CP at 163rpm

50'

e'30

970

Fig. 15 Cavitation Patterns

on HSP E at 163rpm

HSP -tI N 1L3

- -

163 71 rpm

rrcsurd by Lcser (modI) I i I

I

Cor,.'.163Rt

T

t

i

-

Ir---:1.

-i : -rl

'i

-k-i I ii

'!l'

i Ji I I i --f--S-i

I.---i j

i,

I

iij

i i j_ 18O 03 VTA/VM 9 3C ê r _7O 180 170 160 150 140 130 120 110 100 90

j j Aj M Si Fj F3 t i M M 5i Fj F3 Mt [ Fort

I::L

MPltO.2B (CPI A 149 g _? moieL t II)1ro.sttij A 149 1 . 163 >O.hp x 272 J 90 X Fort "s 30 -30 S tar bot rd

Fig. 18 ist Component of Fluctuating Pressures (CP) Model Ship CP HSP-fl t'L(rpm) A A 149 s o 163 o 171

Fuit Socle Ship

X 163 Ai At Si F) F) 5

I

-30-20 40 60 e

Variatíon of Cavity Volume

MPNO 220 (lISPa) N

-30

-60L

li)

Fig. 19 ist Component of Fluctuating Pressures (HSP ) 00',-A o o a A 69 I 63 I 71 63coco)J 49 63 72 rncrit

sp

)4p OO4 A3 At Ej Et 320 340 Fig. 17 s -C si St 53

1/3 OCL.VE SPECTRUM SEI UN-MARU Model ex per i ment Cony. Propeller H.S.P. U Port Side _r 2Ç0rpS. 191] (Rn 180 170 160 150 I 60 1 30 120 110 100

IL

IL

90-lpI)

Fig. 20

Noise

iii LI

Cony. Prope Ile

Non Cavi

-

1

-20

-s,-Cony Proçe ter

163RPM - I- SP. II

HI'

IlonCavi I i --i-- -I--i i -___I I I ___I -i I j I_ -__I_ L_LL Si) 10) 2(0 5(X) 1k 2k 5k t I 1x6 F. 3'BF.

Measurement

Ofl

Propeller

i

-r-

lISP. t 163 RPM -X -{ 10k 20k SOl 1(I)h Hz

Models

0

20

40 60 1C) ¡CO Skew Angle/{3O0/zJ 0/,,

l/) O, 1AV SPEC I RUM SEIUM MAOU Full s ale Conipal d with model iesults

H_SPI' 1631 ¿PM. 160 150 1/,0 130 120 110

j:

r

--i-

-

r-

4 ---J-

±

--I-

---Slarboard Side Ful scale

Estimated rom model experiment ( Levko'dSkU

100

Ii

L L_ 2 ) 20 50 (X) 2(0 503 1k 2k 1.6.E 3B.F.

Fig. 21

Comparison of Measured Full Scale Data

and Estimated

Full Scale I)ata based on Model Test

Results

lia,

i

TYPE YEAR 5(RI) Tanker 1967 Ç2) 5 Ore/llulk/Carrier 1975 ( 4 Ito/Ito 1979

®

3(CPP,RL) Fishing boat 1981 1982 4 Inland vessel 1982

®

5(5R183) Training s6ip 1982

®

S Car Carrier 1983 4 (SRi) 11,/Ito 1982 CL 6O-cL

i)

ci. 40-

(I) Q. <1 20- C) T 0) o

i)

1 1 IL' I Amp, of fluctuating pressure

loo-() Mactel A : Ship W si (tic prime Occurrence of cay. o

Fig.

22

Re].atious1tii lie tween Reduction Rate of Fluctuating

Pressures and Skew Angles

d