Cavitation tests in non-uniform flow on screw propellers of the atomic - powered oceanographic and tender ship - comparison tests on screw propellers designed by theoretical and conventional methods -

(1)

ARCH

Lah y. Schsbowkunde

'Y. I

Techthche HaschooI

Deift

No. 12

PAPERS

OF

SHIP RESEARCH INSTITUTE

Cavitation lests in Non-uniform Flow on Screw Propellers of the Atomic-powered Oceanographic and Tender Ship

Comparison Tests on Screw Propellers Designed by Theoretical and Conventional

Methods-by

Tatsuo ITO, Ilajime TAKAIIASIII and lliroyuki KADOL

March 1966 Ship Research Institute

(2)

Cavitation Tests in Non-uniform Flow on Screw Propellers

of the Atomic-powered Oceanographic and Tender Ship

Comparison Tests on Screw Propellers Designed by

Theoretical and Conventional

Methods-by Tatsuo ITo,

Hajime TAKAHASHI and Hiroyuki KAD0I

Abstract

Four model screw propellers were prepared, of which three are

wake-adapted propellers designed using the vortex theory and one is

designed by the conventional method.

Open water and cavitation tests of the model propellers were carried

out in order to make clear the characteristics of cavitation on the pro-peller blades of the atomic-powered oceanographic and tender ship' and to obtain the design data for it.

A propeller of a ship works in the non-uniform flow at the stern.

Therefore, the wake pattern behind the ship was reproduced in the

cavitation tunnel, where cavitation tests were performed.

1. Introduction

Utilizing the atomic power for driving the marine engine will be followed by the increases of speed and power of the ship, and the

pro-peller will work under the severer condition than in the case of the

ordinary ships. As the result of it, blades of the propeller will be in

danger of cavitation erosion.

*Numbers in brackets designate References at the end of the paper.

(3)

2

We have few avai1abl data, however, for such a problem, and the

present theoretical and conventional methods of designing propel 1ers do

not sufficiently take the effect of non-unifom flow on cavitation into

consideration.

Therefore, in studying the propulsive performance of the atomic-powered ship, the characteristics of cavitation on the propeller blades

must be investigated carefully.

2. Model Propellers

2.1 Design Condition

The model propellers were designed to suit the principal dimensions

and particulars of the ship decided by the Fundamental Design Group. The principal dimensions and lines of the ship are shown in Table 1

and Fig. 1. The actual propeller is to have five blades and a diameter

of 4. 20 m and is to be manufactured in Ni-Al-Bronze. At the design point, the thrust coefficient K is 0. 169, the advance coefficient J, 0. 480, and the cavitation number A, 5. 70.

The wake distribution, which is necessary for designing the three

propellers using the vortex theory, was estimated from the wakes

measured behind Series 60 models2.

The estimated wake distribution is shown in Fig. 2.

Table 1. Principal Dimensions and Items of Ship

Hull

LppXBXd = 114. 0mX19. 0mX6. 40m Displacement=8, 925 tons

CB=O.625, Cp0.656

Ship speed = 18. 1 knots

Main Engine Turbinel set Midship engine Power=10, 000 SHP (MCR) R.P.M.=202 (MCR) Propeller -Diameter=4.20 m No. of blades=5 Solid type

(4)

2.2. Design Methods of Modél Propéllers

Among the three wake-adapted propellers which were designed by the vortex theory, one propeller (M. P. No. 1531) satisfies the design condition of the ship, and the others, were designed at the same condi. tion as M. P. No. 153.1, except for the increased, ï value by 14% for one (M. P. No. 1532) and the decreased i value by 11% for the other

(M. P. No. 1533). The propeller (M. P No. 1534) which was designed using the design charts of AU type propeller series3 satisfies the design condition of 'the ship. The diameter of the model propellers is 20 cm and they were made of aluminum alloy. Particulars of the model

pro-pellers are shown in Fig. 3 to Fig. 6.

The wake-adapted propellers were designed by the combined method of N.S.M.B.4 and Eckhardt and Morgan5). The shape of blade section was chosen to be NACA 16 thickness distribution on a = 0. 8 mean line6. In obtaining the camber ratio and thickness ratio, the cavitation number: aR at each radius was decreased by 20%. The theoretical design pro-' cedure is shown in Table 2.

3 Design Data Wake Distribution Ideal Efficiency "Goldstein-factor" circulation Distribution Induced Curvature Correction Friction Loss correction Shape of Profile,

Mean Line

Thickness Distribution

Table 2 Design Procedure

J=0.480, K==0.169'

Series 60 .

-Acc. to Kramer with Empirical.

Correction 965 (uncorrected) Acc. to Eckhardt-Morgan (with Finite Hub)

tan ßi= (lJii) (1w/1w') tan ß

Acc. to van Manen Acc. to Eckhardt-Morgan Acc. to van Manen N.A.C.A. a=0.8

N.A.C.A. 16

In the case of the' conventional design method, an extrapolation for expanded area ratio was used, as the design charts of AU type propeller

series have two values of expanded area ratio, i. _{e. aE=O. 5 and 0. 65.}

The shape of blade section is the MAU type7), and the radial pitch dis-tribution is constant.

(5)

4

ntimber CR, are shown in Fig. 7. In. this I figuie, A i based upon the speed of advance of the propeller VA, and CR based upon the relative

velocity VR of a blade element at 0. 7R. Spot "a" shows the design pOint of this ship where c4 = 5. 70 and spots "b" and "c" show the

design points where A =6. 50 (14% increase) and 5. 07 (11% decrease)

respectively. As the limiting line which is used in the Ship Íesearch

Institute passes almost through spot "a ", the expanded area ratio of M. P. No 1534 was adjusted to be equal to that of M.P. No. 1531.

3. Open Water Tests

3.1 Test Procedure

Open water tests were carried out in Mejiro No. 2 Towing Tank of the Ship Research Institute. The speed of rotation of the model

propel-lers was 20 r.ps., the immersion of the propeller shaft 20 cm, and the

water temperature 17. 8°C. The various forms of Reynolds' number are shown below and the values of Reynolds' number are shown in Table 3. Scale effect is negligible.

Rn1nD2/ R2 = nD2/1J.aE/Z Rn3 bnimflD2/ where Rn =Reynolds', number n = speed of rotation (= 20 r. p.s.) D = diameter of propeller (=20 cm)

= kinematic viscosity of water aE = expanded area ratio

Z = number of blades

(6)

Table 3 Reynolds' Number

3.2 Results of Tests

The results of the tests are shown in Fig. 8. The values of thrust coefficient K, obtained by the experiment were slightly lower than the

design point. It is often pointed out that the propeller which is designed

using the vortex theory has a smaller pitch than required, therefore a

pitch correction is necessary. But, as it is one of the purposes of this

research to investigate the amount of pitch correction required, the final

empirical correction for pitch was not addéd to the calculated pitch.

From the results of open water tests, it is necessary to increase the final pitch by 1. 5 to 3. 0% in the case of very wide propellers of five-blade. M.P. No. 1534 which was designed by the conventional method, had the same trend as the other three propellers. It appears that the accuracy of the extrapolation was not sufficient using the design charts for

ex-panded area ratios of 0. 50 and 0. 65.

4. Cavitation Tests

4.1 Test Procedure

Cavitation tests were carried out in the Cavitation Tunnel of. thé

Ship Research Institute.

The wake pattern mentioned above (Fig. 2) was reproduced at the

propeller position in the test section of the cavitation tunnel and cavita-.

tion tests were performed in this simulated wake pattern. For the

reproduction of the wake pattern, the wire meshes were fitted normal to

5

M. P. No. 1531 1532 1533 1534

R1x 10-e Open water test 7.55 7.55 7.55

. 7.55

Cay, test 13.7 13.4 14.0 13.4

R,2x 10-s Open water test 1.18 .

1.07 1.31 1.18

Cay, test 2.14 1.89 2.43 2.09

R3x1O' Open water test 2.32 2.09 2.58 2.32

(7)

6

the direction of main flow at a posision upstream of the model propeller. A wooden plate (thickness 3 cm) was located in the plane corresponding to the ship centre-plane. There were honeycombs on both sides of the

plate to maintain the high wake zones as far as the position of the model propeller. The after shape of this plate is similar to the ship screw aperture. The shaft of the model propeller passes through the

wall of the water tunnel and is connected to the .dynamometer and driving motor. The arrangement is shown in Fig. 9. The simulated

wake pattern, which was measured at the position of the model propel.

1er using a pitot comb, is shown in Fig. lo.

The thrust identity method was adopted for the cavitation tests in

non-uniform flow. In this method, tests in non-uniform flow are carried

out under the condition in which the value of thrust coefficient KT in

the water tunnel is equal to that behind the ship. However, as the

self-propulsion tests of the model had not been performed, the cavitation tests in non-uniform flow were carried out using the K value estimated

from the results of the open water tests. As the curves of thrust and

torque coefficient of the model propellers in Fig. 8 did not pass through

the design point, the cavitation tests were performed at the same value

of load coefficient as in the design condition, i. e. K/J2 = 0. 734. The

test conditions are shown in Table 4.

Table 4 Test Point

The experiments for each propeller were carried out at the values of 5. 3, 6. 0 and 6. 8. The points .of tests are shown in Fig. 7 as spots

A, A' & A" for M. P. No. 1531, B, B' & B" for M. P. No. 1532, C, C'

& C" for M. P. No. 1533, and D, D' & D" for M. P. No. 1534. In addition, the points of thrust-breakdown were obtained by keeping the

speed of rotation of model propellers and water speed constant, and decreasing the pressure i. e. R value gradually. The points of thrust-breakdown are represented by spots A", B", C" and D" in Fig. 7.

M. P. No. 1531 1532 1533 1534 Designed Value

0.165 0.162 0.161 0.163 0.169

(8)

7

Thé tunnel water was' cleaned by the filter using diatoms before thé experiments. During the experiments the mean water temperature was

19°C and the air content of the water a/as was about 50%. The

Rey-nolds' numbers, which were of higher values than' in the open water tests, are shown in Table 3.

4.2 Results of Tests

As shown in Fig. 11, one revolution of the blade was divided at intervals of 18° or 9° and the positions of the blade were represented

by numbers from O to 19'/2. No. O means the blade is at the top, No.

10 at the bottom. The cavitation patterns, sketched using the stroboflash

lighting are shown in Fig. 13 to Fig. 36 and the photographs shown in Fig. 37 to Fig. 48 were taken using the flash lighting of duration 2ps.

The notation of the sketches is shown in Fig. 12. In these sketches, F.C. means cavitation on the face of the blade and for convenience, the pat-terns of face cavitation were sketched on the blade contour from a view

of the back side, together with the patterns of back cavitation. The figure on the blade in the photograph shows the position number of that blade. The number in bracket ünder eàáh photograph indicates Fig. No. of the corresponding sketch of each propeller.

In uniform flow, the patterns are the same at every position, but in

non-uniform flow, they vary remarkably according to the pòsition of the blade. In the regions where the values of wake fraction are high near

the top and bottom positions, face cavitation does not occur but back

cavitation is severe. In contrast, generally speaking, in the regions

where the values of wake 'fraction are low near No. 6 and No. 14 posi-tions, face cavitation appears and back cavitation disappears.

In these experiments, bubble cavitation on the back of thé blade

occurred very slightly. In the case of the propellers designed by the vortex theory, a little cloud cavitation was present on the face of the

blade. From the point of view of cavitation erosion, sheet cavitátion is not dangerous, but bubble and cloúd cavitatiOn especially the latter

are very dangerous8. Cloud cavitatiòn is not usually observed in

uniform flow.

(9)

8

theory with each other at each design point, i. e., spots A, B and C, There is almost no differerce in cavitation patterns.

Comparing the two model propellers (M. P. No. 1531, 1534), for example Fig. 15 which were designed at the same cavitation number, the area with covered with the sheet cavitation occurred on the back of blade of M. P. No. 1534, is slightly larger than that of M. P. No. 1531. The blade positions where cavitation occurred in both propellers are

compared in Fig. 49. The positions for occurring of sheet cavitation on

the back of the blade are almost the same in both propellers, but M.P. No. 1534 produces bubble cavitation over a little wider swept arc than

does M. P. No. 1531. In the case of face cavitation, M. P. No. 1534 is much superior to M.P. No. 1531, since cloud cavitation, which is most dangerous from the erosion point of view, was never seen on the blade of M. P. No. 1534, and there was no face cavitation on it at the

star-board side.

Reduced frequencies of the blade elements of each propeller are

shown in Table 5. Reduced frequency presents the degree of unsteady condition and the critical value of reduced frequency at which unsteady cavitation is severest is about O. 3O. 48) The values of reduced f

re-quency for face cavitation at rl R = 0. 7 on the port side, are in the

critical range. This fact n-iight make clear the above-mentioned

pheno-mena, i.e. face cavitation occurred only on the port side in the case of

M. P. No. 1534.

Table 5 Reduced Frequency

M. P. No. r/R=0.9 for Back Cay. r/R=0.7 for Face Cay.

Top Bottom Starboard Port

1531 1.33 6.15 0.76 0.40

1532 1. 17 5.44 0.67 0.35

1533 1.52 7.03 0.86 0.45

(10)

5. Conclusions

5. 1 Empirical Pitch Correction in the Case of

Propeller Design using Vortex Theory

It is necessary to correct the final pitch by about 1. 5-.-3% in

de-signing such five-bladed propellers as were used in these experiments. 5.2 Comparison at the Design Points

In the case of the three model propellers designed by the vortex theory, there is not much difference in cävitation phenomena at the

design points, i.e spots A, B and C.

Concerning back cavitation, the model propeller designed by the conventional method (M. P. No. 1534) is slightly inferior to M. P. No.

1531 designed by the vortex theory, but the former is much superior to

the latter from the point of view of face cavitation, especially cloud

cavitation.

5.3 The Line of Thrust Breakdown

The line of thrust breakdown in Fig. 7, shows the critical line of decreasing thrust, i.e. decreasing efficiency of propellers. Therefore, if

we consider only the efficiency drop, this line is a limiting line for the

design of propellers. But, this line cannot be chosen as the limiting

line, because severe cavitation occurs at the top and bottom positions near this line, and the blades are in danger of erosion.

The results of tests which were performed using four-bladed propel.

1ers at the Statens Skeppsprovningsanstalt are also shown in Fig. 7 by

the synboID9.

5.4 The Limiting Line for Designing Propellers

There are N. S. M. B.'s and Burrill's line, etc. as the limiting line

for designing propellers. When the five-bladed propeller for this ship is

finally, designed, it will be desirable to choose the limiting line of the

Ship Research Institute slightly lower than Burrill's 5% back cavitation line'°. This is to prevent blade erosion by making the face cavitation

(11)

10

free and the back cavitation as slight as possible.

Concerning the shape of blade sections, the MAU type is

recom-mended because it is free from face cloud cavitation.

Acknowledgements

The work described here has been carried out as a part of the

re-search programme of the Atomic Powered Ship Rere-search Association of

Japan. The authors wish to thank members of the Propulsion Group of

the Association for their valuable suggestions.

References

M.Yamaguchi

"Preliminary design of the atomic-powered oceanographic and tender ship in Japan" Zosen-Kyokai-shi, No. 339, 1962.

G.R. Stuntz & others

"Series 60-the effect of variations in after body shape upon resistance, power, wake distribution, and propeller excited vibratory forces" S.N.A.M.E., 1960 K. Tsuchida & others

"Open water test with modern five-bladed propeller models" Zosen-Kyokai-Ro-nbunshu, No. 102, 1958

W.P.A. van Lammeren and J.D. van Manen

"The design of wake-adapted screw and their behaviour behind the ship" TI. E.S.S. Vol. 98, 1955

M. K. Eckhardt and W.B. Morgan

"A Propeller design method" S.N.A.M.E., Vol. 63, 1955 I. H. Abbott and A.E. von Doenhoff

"Theory of wing sections" Dover publications, Inc. A. Yazaki

"The design of AU-type ship screw propellers" Reports of Transportation Technical Research Institute vol. 11 No. 7 1961

T. Ito

"An experimental investigation into the unsteady cavitation of marine propellers" Proceeding of lAHR symposium, Sendai, Japan, 1963

or

Papers of Ship Research Institute, No. 11, 1966 H. Lindgren

'cavitation tunnel tests with merchant ship propellers" S.S.P.A. Nr 48, 1961 L.C.Burrill and A.Emerson

"Propeller cavitatibn : Further tests on 16 in. propeller models in the Iing's Colledge cavitation tunnel" N.E.C.I.E.S. Vol. 79, 1962-3

(12)

BOSS

h/abe Frîc1iOfl(%)

Fig. 2 Estimated wake distribution

11

(13)

r-.pfl..r.fl1 flr.7,S FSVL'V 1r-W, frtIi#fl77 S. (je.?. y-#.-v_-.,r ,n7ñdrV-Z,,bjpflp 7'1az1., pad 1S#1StT#7 IflYa7.a F7flS?t-.dr.MsW_v_rfl7. n, f S.. WJ#

I

lII

J'y

I__

VI,..

LLn.p,cr.ni...ui 95 (? / 7.O (f 70 24.2 ('-.,l ,.q.jfr. cri. 91) 24 q. S ? . S RADIoS lac Fig. 3 M. P. No. 1531 /

(14)

r.PvJhnn.rJ.,s.anpnwrIW

Vt7,

s-,r.tna.

(15)

ah,aVWtflalñ7iP5#flfl, -:

na, tflsnn.rPS

I. IflLdSZfl

t71CÇ1SflZ,2'I#J

.czt,S,,sa2flÍpt p.7,/i. y..)rA

s,, /S.SSCP,,,'rJ./irinJ

ji____________

'I,

L

.-litA

i-

tI

-I

t

40

iiiii____

L.-.----_,w_I.I______________________

I

30

iPJ-vIIIII.Ma.___

-_

4. pn-l=fl-

.&. R4D1(L5 /00 Fig. 5 M. P. No. 1533

(16)

Fig. 6 M. P. No. 1534 i7.8 A'AD/U.5 /00 7.5 ,__-______so.f A 90 J" 3a.3 f7.?

//

25.2

k'

80 o -II i II 31.8 29 4 ________________________________

-IIta

r.vrnprns.q.vss.-tnr.rsp-723 flß

_{¡j, j}

00

IIII1

-24.4 ,5rt,L;w.vu',.z,.pcp

___________

'.

ii a

:;zz:

1 1,

40

W41A

u

30 .. 1iiiiiìiiIL

-

UI i

____

20 '. \. 2/4 ,.l..

(17)

16 30 24 j O. 0. 0. 5 0.20

Fig. 7 Cavitation diagram

o

-

T/IRLJS PROJECTED RELATIVE SPEED T

411*1111

r

Ao Vo

-V.

AREA VELOCITY Ar o.?OrRAo3 OP ADVANCE A

i

c' C C

LOCAL CAVITATION NUMBER

I

A707M

I I I I I I

(18)

-.3 k .2 a DIRECT/ON OFriôiI j. V/

Fig. 8 Results of open water tests

WAKE PR0DUc,N

W'RE I-IF!-1

,/rn'ìFy rO.-1R

/

Fig. 9 Arrangement of cavitation test in non-uniform flow

O P FR VA TI/JAl 4//ÑF)/JV RI/I) I) FR 1V MIJA4FTPc' 17 I..1ARA5 AI. p. /53/ /532 - s3J

-. /534

Os .04 03-02 0 0 .1 .2 .3 .4 .5 .4

(19)

18 0.8 0.2

-O

O Top MA R K 5-: -__-..----_EST/I-1,4TED /20 IN D&G. ßOTTO4

Fig. lo Wake distribution at each radius

ROTTO/vi

Fig. 11 Position number of blade

o.S R o.7R MEASURED o. R /.O R 240 J00 J o 7-Op

(20)

Fig. 12 Notation of sketch

(21)

M. P. NO. / 532 M. P. NO.

/53,

M. P. NO. /533 M. P NO / 534

Fig. 13 Cavitation pattern at No. O position in non-uniform flow

20

(22)

it-I. P. NO. i c32 M. P. NO.

/53/

M. P. NO. /533 M. P. NO. /534

Fig. 14 Cavitation pattern at No.34 position in non-uniform flow

21

(23)

¡44.P. NO. / 532 M. P. No.

'53/

it-I. P. NO. /533 M. P. NO. / 534

Fig. 15 Cavitation pattern at No. i position in non-uniform flow

22

(24)

MP. NO. /532 M. P. NO.

/53/

M. P. NO. i533 ,t-f. P NO.

/534

O'A .&7O OÁ -&O

Fig. 16 Cavitation pattern at No. 2 position in non-uniform flow

(25)

24 4-I. P. Na / 532 it-I. P. NO.

/53/

M.P..NO. ,333 M. P. NO.

/534

D

Fig. 17 Caviration pattern at Np. 3 position in non-uniform flow

(26)

ìt-I.P. NO. / 532 M. P. NO.

/53/

M. P. NO. /533 M. P.

NO-534

O;ò, ".O7

(27)

26 i-1.P. NC. 1S32 ii-1. P. NO.

/53/

M. P. NO. ,S33 M. P. NO

/534

Fig. .19 Cävitation jattern at No.5 position in non-uniform flow

(28)

M. P. NO. / .c32 M. P. NO.

'53/

M. P. NO. iS 33 M. P. NO.

/534

D

'D'

27

(29)

44. P. NC. / 32 M. P. NO. /5.3/ ¿-1. P. NO. 1533 M. P. NO.

/534

28

(30)

it-I. P. N / 532 M. P. NO.

/53/

M. P. NO.

/534

D'

'D'

O:: .7o O;4 -6.o

0o. O7

(31)

1%-1. P. IVO. /532 ,%-1. P. NO. 153/ M. P. NO. /333 M. P. NO.

/534

ç

ç7

ç!

30

(32)

It-I. P. /VO. / 532 i%-I. P. NO.

/53'

M. P. NO. i333 M P. NO.

534 ç7ç7

D

'D'

31

(33)

32 A-1. P. N / 532 M. P. NO.

/53,

M. P. NO. i333 M. P. NO.

534 D'

'D'

(34)

/t4. p ivo. / 32 iif. P. NO. 153/ A-1. P. NO. /533 M. P. NO /534

Fig. 26 Cavitation pattern at No. lO/2 position in non-uniform flow

33

(35)

34 44. P. Na / 532 M. P. NO.

/53'

M. P. NO. i533 M. P. NO

/534

(36)

44. P. NO. i 532 /t1. P. NO. 153 / M.P.NO. /333 M. P. NO.

534

D

35

(37)

36 1í4. P. A/O. / 532 M. P. NO.

'53,

M. P. NO.

,j33

M. P. NO. /534 D

D'

O .7O OA

(38)

4-1. p. ivo. / 532 /frf P. NÒ.

/53/

M. P. NO. i333 M. P. NO. 34 D" D

Fig. 30 Cávitation pattern at No. 14 position in non-uniform flow

37

(39)

38 /'4. P. NO. / 532 M. P. NO.

/53/

M. P. NO. i533 M. P NO / 534 D

'D'

(40)

M. P. NO. /532 M. P. NO..

'53/

M. P. NO. S33 M. P.

NO-/534

D'

'D'

39

(41)

40 /t-I. P. NO. / .c32 M. P. NO.

/53,

M. P. NO. /533 M. P. NO

534 D'

'D'

(42)

M.P. NO. /532 M. P. NO. /531 M. P. NO. /534

cJ,c7

533

M. P. NO.

'D'

O .7O 0:4

O:A ".°7

(43)

42 it-I. P. NO. / 532 M. P. NO.

/53,

M. P. NO. ,533 M. P NO.

534

D

i,,

(44)

M.P. NO. /532 M. P NO. /53/ M. P. NO. /533 M. P NO. I 534 D D'

Fig. 36 Cavitation pattern at No.19)4 position in non-uniform flow

43

(45)

44 Corresponding to Fig. (35) 3 M. P. NO. 1531 Spot A 5. 70 (36) - (13)

Fig. 37 Photographs of cavitation pattern

L (14) (16) (23) (25) (27)

f

--J A (17)

(46)

M. P. NO. 1531

Spot A' A6. 50

45 Corresponding to Fig. (35) (36) (13) (14) (15) (16) (23) (25) (27) 3 (17) s e

(47)

46 Corresponding to Fig. (35) M. P. NO. 1531 Spot A" ASO7 (36) (13)

(14) (15) (16)

(23) (25) (27)

3

(48)

Corresponding to Fig. (35) (17) A M. P. NO. 1532 Spot B (36) r

47

(23) (25) (27)

.. FACE

3 CA

(49)

48 FA 3 (17) M. P. NO. 1532 Spot B' 7n5.7O

(13) (36)

Corresponding to Fig. (35)

(14) (15) (16)

(50)

Corresponding to Fig. (35) (17) M. P. NO. 1532 Spot B" 1n5. 07 (14) (15) (16) F (23) (25) (27)

49

(36) (13)

(51)

50 (17) M. P. NO. 1533 Spot C 4=5 07 (15) t (16) (23) (25) (27) FAC

3,C

(52)

L. Corresponding to Fig. (35) (17) M. P. NO. . 1533 Spot C" 0A == 5. 70 (36)

Fig. .44 Photographs of cavitation pattern

(13)

51

(14) (15). (16)

(23) (25) (27)

(53)

52 Corresponding to Fig. (35) (23) (17) M P. NO. 1533 Spot C' aA=6.50 (36) - (13) (25) (27)

(54)

Corresponding to Fig. (35) M. P. NO. 1534 Spot D C4==5. 70 A (36)

Y

53

(14) (15) (16)

(23) (25) (27)

(55)

54

M. P. NO. 1534

Spot D'

6. 50

Face cavitation free at starboard side

s

(14) (15)

(23) (25) (27)

(56)

M. P. NO. 1534

Spot D"

CA=5. 07

(15)

s

(23) (25) (27)

Face cavitation free at starboard side

55

(57)

56

ÑA('J( ('AVI7AT1fAI r, P

R/TTPA4

REMAPK 44. P NO. ,s3/ WAKE AOAPTEI

M. P NO. ISJ4 : coNvcNr,CNAL

FACF (A UI TP TI

Fig. 49 Comparison of cavitation patterns of M. P. Nos. 1531 and 1534 at each blade position in non-uniform flow

/53/ /3-34

51-/EETCAV

ßUSBLE CA V -°--°-c - $ -.