Investigations into the propulsive performance of simplified full hull forms

TECHNISCHE UNIVER$1TgT Laboratorium voor $choepshydromochaca Archlef Mekeiweg 2,2628 CD Deift TeL: 015. 785873- F _{015.. 7818}

Investigations into

the propulsive peforiñance

of

simpl (fled full hull form s

LIST OF SYMBOLS

IM

of transverse cross-section of a bulbous bow

AE Expânded blade area of propeller AM Areà of midship section

A0 Propeller disc area=/42rD2

A Design water plane area

A Area of maximum transverse section of a ship

B Breadth of ship moulded

c Chord length of propeller blade section

CA Incremental resistancè coefficient for model-ship correlation

A213.V CA Admiralty coefficient = Pl, V C8 Block coefficient-B. T - A213 V3 Admiralty coefficient -AM C,1,, Midship section coefflcient=7-.

Cp Longitudinal prismatic coefflcient

- ÄxLpp

Designed load waterline coefficient

_{= L.B}

d Hub diameter of propeller

D Propeller diametet

fBT TaylOr sectional area coefficient for bulbous bow

u V

F,,

Froude number=

li-ygLpp g Acceleration due to gravity J Advance coefficient of propeller

-.Q

KQ Torque

2D5

K7. Thrust coefficient =

pn2D4

Lenght of ship between perpendiculars

N Revolutions per minute of propeller

n Revòlùtions. per secônd of propeller Delivered power at propeller. 2jrQn

PE Effective power= R7.. V P07 Pitch at O.7r Pr Pitcu at root

-P, Pitch at tip Q Torque R Propeller radius

r Distance from propeller axis

R7. Total resistance

S Wetted surface including rudder. T PrOpeller thrust

T Draft, mulded

z Maximum thickness ofpropeller blade sections

TR7..

t Thrust deduction fraction =

CE

PE

V Speed of ship or model

V4 Speed of advance of propeller

V, Radial velocity conióhent in propeller plane

V( Tangential velocity component in propeller plane

i",, Transverse velocity component in propeller plane = v"V,2 + v? V Axial velocity component in propeller plane

V_- V4 w Nominal wake fraction₌

We Effective Taylor wake fraction = 1/2(WT+ WQ)

WQ Taylor wake fraction determined from torque identity WT Taylor wake fraction determined from thrust identity

X Distance to propeller axis = j-Z Number of blades

A Displacement weight in sea water of 15° Centigrade n8 Propeller efficiency behind ship

D Propulsive efficiency =

KrJ

Propeller efficiency in open water = .

-KQ 2jr

R Relative rotatie efficiency =

nR Hull efficiency -

_L

O Rake angle of propeller

¿ Scale ratio

V Displacement volume

A Displacement weight in sea water

y Coefficient of kinematic viscosity of water

CONTENTS

page Summary

I Introduction . . ..

. .5

2 Model and test description

3 Extrapolation method

...

4 Presentation and discussion of the results 4.]

Resistance ...-

.

4.2 Propulsion and propulsion fâctors

4.3 Wake measurements 4.4 Flow visualization.

5

Comment on the results...

₃₀

6 Conclusions...

... :. ...31

References

. ...31

5 10 10 12 18 22 lo

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© Netherlands Maritime Institute

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I Introduction

Shipyards sometimes consider the application ofsimpli-fled ship forms as a means of reducing building costs. Building series of ships is another method for reducing such costs. A combination of both methods may also lead to further reductions. Studies have been made all over the world and some simplified ships have been built with more or less success [1]. lt appears that the simplification must not lead to a significant loss in pro-pulsive performance.

In order to investigate the possibilities of simplifi-cation of a full ship, the hull form of a 455,000 TDW Product Carrier was chosen. The conventional hull form was slightly improved. This hull form is, however, in the

shipyard's opinion, somewhat more complicated to

build. As a first step to a simplification, a sharp bilge. form was introduced. Next, the yard proposed a form for which the projection of the bilge line in the body plan became a straight line intersecting the base line under 450 The fuller sections lead to an increase in displacement of about 3.6%. A third step was made by decreasing the dis-placement by about 3.6% by reducing the parallel mid-body of the vessel.

The investigations were extended by introducing

developable surfaces for side and bottom plating, except for the "gondola" which was not simplified so as to avoid a change of the flow into the propeller. These proposals were made só as to arrive at optimum angle between the projection of the bilge line in the body plan and thé base line. The three investigated angles were 63°, 55° and 47°. An effort was made to keep the displacement, centre of buoyancy,etc. equal to that of the improved version of the conventional hull form. A last step was made by a variation around the 55° angle bilge projection line by

giving it a curved form. Here, both the side and the

bottom plating were formed by cylindrical surfaces. As the version with the 47° bilge line showed promis-ing results, the programme was extended by modifypromis-ing

INVESTIGATIONS INTO THE PROPULSIVE PERFORMANCE

OF SIMPLIFIED FULL HULL FORMS

by

IR. A. JONK AND A. REM Nederlands Scheepsbouwkundig Proefszarion

(Netherlands Ship Model Basin)

Summaiy

A series of models were investigated in the Deep Water Basin of the N.S.M.B. The models represent the hull form ofa single screw 455,000 TDW products carrier. The investigations were focussed mainly on the feasibility ofa simplified afterbody with regard to

the hydrodynamic characteristics.

A conventional hull form was optimized and thereafter simplifications were made step by step.

In this report some results of propulsive performance and flow behaviour of various hull forms are given. An attempt has been made to analyse the propeller-hull interaction.

the "gondola" in two ways, viz., a version with a more voluminous "gondola" and a version with a less volu-minous "gondola".

2 Model and test description

The basic hull form is that of a 455,000 TDW single screw Product Carrier with a Hogner type of afterbody combined with U-shaped sections. A bulbous bow was adopted with fBT= 0.186.

The model ofthe basic hull form, denominated model 4770, was made of wood to a scale of i : 50. It was manu-factured in two parts, a forebody and an afterbody, so that various afterbody configurations could be fitted to the forebody.

The simplified afterbody configurations, fitted to the basic

forebody, were denominated model 4770A

to 4770H.

The afterbody sections of model 4770A and model 4770B are the same, except that, in ship model 4770B, sharps bilges were introduced. Both hull forms tend towards a "pram" type afterbody.

In model 4770C, the projections of the bilge diagonal in the body plan was a straight line intersecting the base line under 450V The fuller Sections caused an increase of the displacement and a more aft position of the centre of buoyancy. To reduce the displacement, the parallel midbody was reduced leading to ship model 4770D.

-All the above-mentioned configurations were manu-factured according to lines plans supplied by Verolme United Shipyards, Rotterdam.

After testing these models, the N.S.M.B. desied

four different versions of simplified "pram" type

after-body configurations, denominated 4770E through

4770H.

The models 4770E to 4770G have sections described by vertical elliptical cylinders and horizontal conical cylinders. The distance of the top of the cone to the

M 4770 E

M 4770 F

M 4770 G

6

Fig. i Afterbody configurations.

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centre line has been varied systematically. The intersec-tion ofboth cylinders leads to a straight projecintersec-tionin the body plans; the projectión of each model intersecting the base line at different angles. The bilges were also

formed by an elliptical cylinder. Model 4770H has

sections described by vertical and horizontal elliptical cylinders with a sharp bilge. All four ship models have

the same "gondola" in front of the propeller. Fig. i

shows the models 4770E to H, whereas Fig. 2 shows the body plans of forebody and afterbody configurations.

As ship model 4770F provided the most promising results, some additional tests were carried out by modi-fying the "gondola" only. Two versions were tested, vii., ship model 4770J with a more voluminous "góndola" and ship model 4770K with a less voluminous "gondola" than ship model 4770F.

Fig. 3 shows the afterbody configurations of these models, whereas in Fig. 4 the body plans are given.

The curves of sectional areas (Fig. 5) show that ship model 4770C and D are the fullest. Models 4770A and B show a somewhat reduced aft shoulder with regard to the basic form, model 4770. Model 4770E to H have the same curve of sectional areas, but aré improved with re-gard to the basic form by a further reduction of the aft shoulder, keeping the positión of centre of buoyancy and diplacement equivalent to that of the basic form (within normal tolerances).

Obviously the curves of sectional areas of the ship models 4770J and 4770K differ slightly from those of ship models 4770E to H because of differences in the "gondola".

The principal characteristics of the ships represented by the above-mentioned models are given in Table I for the loaded condition, whereas Table U shows some figu-res for the ballast condition.

For the basic hüll form, and consequently for the sim-plified húll fòrms, it was assumed that a propulsion plant would be installed capable of developing 43,000 SHP at 85 RPM. Five-bladed propeller model 4344 of Table I. Main particulars of the ship. Ballast condition.

M 477V

M 477V D

Fig. 2 Body plans.

M 477V

the N.S.M.B. stock was chosen for propelling the ship models 4770 to 4770K during the propulsion and flOw visúalization iests

Table III shows the principal particulars, whereas in Table 1V some information of the propeller blade sec-tions is given. In Fig. 6, the propeller is shown, whereas Fig. 7 shows the stem arrangement of the basic ship model. 7 Denanination -SyITi Unit -- cofguration - -4770 4770A 4770B 4770C 47700 4770E 4770F 4770G 4770M -4770.7 4770K

Length between perndicul-ars a 370.00 370.Ò0 370.00 370.00 358.71 370.00 370.00 370.00 370.00 370.00 373.00

Breadth ixculded - B in 66.00 66.00 66.00 66.00 66.00 66.00 66.00 66.00 66.00 66.00 66.00

Draft nj.1 T a 24.23 24.23 24.23 24.23 24.23 24.23 24.23 24.23 24.23 24.23 24.23

DipiaSIant'1I.sT - in3 494780 495783 496064 512816 :494780 494697 494679 494688 495135 495983 493587

Dizp1acnt weigrlt in sea water A tons 507150 508178 508466 525636, 507150 507065 507046 507055 507513 508383 505927 Uatted surface witit rodear s 2 _{37396 37526 37645 38540 37262 382S2 -38148 38243 39252 38116} 38113

B1k coefficient CB - 0.8362 0.8379 0.8384 0.8667 0.8625 0.8360 0.8360 0.8360 0.8368 0.8382 0.8342

Midship saction coefficient CM - 0.9993 0.9993 0.9993 0.9993 0.9993 0.9993 0.9993 0.9993 0.9993 0.9993 0.9993

Prinsatic coefficient.- C - 0.8368 0.8385 0.8390 0.8673 0.8631 0.8366

-0.8366 0.8366 0.8374 0.8388 0.8348

Longitudinal centre of biYarxCY :

fwd.. of midship (in S of _- 3.45 3.39 3.37 2.07 2'.14 3.40 3.40 3.40 3.38 3.29 3.46

8rcthJdraft ratio 3(1' - 2.72 2.72 2.72 2.72 2.72 2.72 2.72 2.72 2.72 2.72 2.72 Disp1cineeit length/breadth ratio Lu/B - 5.66 5.66 5.66 5.66 5.44 5.66 -5.66 5.66 5.66 5.66 5.66

M 4770 J

M 4770 F

M 4770 K

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Fig. 5 Curves of sectional areas.

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Fig. 3 Afterbody configurations.

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It must be noted that, for the adaptation of the rudder to the stern contour of the different model configura-tions, the heights of the rudders differ slightly from that of the basic model. The distance between rudder bottom and base line and the clearances of the propeller have been kept constant.

The tests were performed in the Deep Water Towing Tank of the Netherlands Ship Model Basin, which has a water depth of 5.5 metres, a breadth of 10.5 metres and a length of 250 metres. .

The testing programme consisted of resistance and propulsion tests at the self-propulsion point of ship for all ship models. The open water test with the stock pro-peller had already been performed.

During the resistance tests, which were conducted

over a speed range 0.111 <F<0.145 (model 4770D

0.113 <F. <0.147) corresponding to speeds of 13 to 17

knots for the full-scale ship - for the load draft, i.e.

M 4770J M 4770F M 4770k

Table II. Main particularsofthe ship. Ballast condition.

24.23 manda speed range 0.120 <F5 <0.154 forthe bal-last draft, ï.e. 7.90/11.00 m, the resistance was measured by a balance dynamometer. Ruddei and bilge keels were not fitted to the model. The propeller was replaced by a streamline cap.

Turbulence was stimulated by using LT.T.C. standard-ized studs, spaced 2'h cm apart at station 19I4.

During the propulsion tests, conducted over thesarne speed rañge as for the resistance tests, the ship model

ws provided with the rudder Thrust torque and RPM

were measured with a mechanical dynamometer.

For sorne configurations, three-dimensional wake

tests were conducted, using the 5-hole Pitot sphere in

combination with very sensitive differential pressure

transducers. The wake surveys were made at port side in

a plan perpendicular to the Thaft axis in way of the propeller. Rudder and propeller were omitted during

the surveys.

Table Ill. Propeller specification, propeller No. 4344.

table IV. Particulars of blade sections;

Fig. 6 Propeller for "simplified" configurations.

Fig. 7 Rudder for 'basic model".

I-Fig. 8 Positions of tufts.

For the ship models 4770E to K tuft tests were carried out with and without running propeller at lOaded draft.

Tuft tests, were also carried out for the ship models 4770F, J andK at ballast draft. The mdvernent of the

woolen tuft's, plcedii nedl at a distance of about 2 cm from the hull, -was recorded by means of à movie camera. The needles were spaced about 6 cm àpart, starting frOm the centre. line and placed on stations as indicated on Fig. 8.

Der,cnnir,ation ' SyTl Unit Ccñfiguration

4770 -4770A 477DB 4770F 47703 4770K

Length twaen

rr.iculars

L ¡n 370.00 370.00 370.00 370.00 370.00 370.00

Breedth irò.üded B . ¡n 66.00 66.00 66.00 66.00 66.00 66.00

Draft sculded T a 7.90/11.00 7.90/11.00 7.90/11.00 7.90/11.00 790Í11.00 7.90/11.00

r1iplacnt voi.m in 160566 175761 175849 176829 178168 175684

DispacTerIt waight in s water tons 185070 180155 180245 181250 182623 180076

Wetted surfa withit . s 2 25281 25232 25281 26038 26010 2034

Denominat.orl Symbol Unit

Diarnéter D

.... IsIs

10000

Pitch at root - r

5190

Pitch at 0.7R P0 ¡lIs' 6192

Pitch at blade tip 555 -. .6400

Disc area . .

2 ₇₈₅₄

Expañded blade area ratio Ae/Ao - 0.587

Projected blade area ratio A/A0 - 0.544

Hub/diameterratio d/D - 0.173

Pitch/diameter' ratio p07/D - 0.61.9

Rake angle'' '

-

O - degr. -3

Number of blades Z - 5 r/R:.. in min C ... in -mm. Position of max.profile.. thickness to leading edge in% of chord length

1.000 21 642 _{.: ..:- '} -0.956 41 1822 ' 49.9. 0.900 '6ó2275

T':.49.9

0.800 101 2605 49.9- ... 0.700 143 2614' 49.0 0.600 189 2522 46.5 0.500 238 2379 43.2 0.400 292 2196 39.6-

- ...

0.300 352 1985 36.3 0.200 416 1758 35.7

3 Extrapolation method

The results of the resistance and self-propulsion tests

were extrapolated according to the two-dimensional

Froude method, using the Schoenherr friction line with

an incremental resistance coefficient for model-ship

correlation CA = + 0.0002. The results have been cor-rected for 15° Centigrade standard temperature of the sea-water.

The results of the selfpropulsion tests refer to the self-propulsion point of ship. These results are directly cal-culated from measured model values without any

allow-ance being made for appendages not present on the

model, nor for wind and sea, so values for the ship are for tank conditions.

The number of revolutions of the ship's propeller are given for tank conditions, without correction for the

dif-ference between the wakes of ship and model and

without any allowance.

4 Presentation and discussion of the results 4.1 Resistance

With each of the models 4770 to 4770K resistance tests were carried out at a full-load draft of 24.23 m even keel. The results are given in Fig. 9. At the ballast draft, being

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Speed in knots Speed in knots

Fig. 9 PE diagram loaded condition.

12 13 14 15 16 17 18 19 20

40000 30 20000 10000 ShipNo Line 4770 4770A 4770B -

-PF totai

7.90/11.00 m, resistance tests were carried out with the models 4770, 4770A. 4770B, 4770F, 4770J and 4710K only. The results of these tests are presented in Fig.10.

Compared with the N.S.M.B.. statistical data the

results of the resistance tests with the basic'form, modèl 4770. are considered satisfactory.

Table V presents thePEvalues at the loaded condition

of the models 4770A to 4770K as percentages of the re-sistance of model 4770. assuming these results to be

100%.

In the comparison as given in Table V, the effect of the differences in displacement is favourable for the môdel with the smallest displacement. To eliminate this effect, it is reasonable to compare on a base of the Admiralty coeffient. being

Table V. Percentages PE for the loaded condition.

2/3 V3

CE-FE

This comparison is given in Table Vi.

These figures show that for the models 4770A to

4770D, the decrease in reSistance(CE) of môdel 4770A

amounts to some 5.5% compared with the resistànce 1

the conventional basic model 4770. Because of the sharp bilge ofmodel 4770B, the resistance rises by 0.2 to 0.7% compared with the rounded bilge of model 4770A.

Model 4770C and model 4770Drn (the shortened ver sion) are respectively about 1% worse and 1% better in resistance than the basic model. lt has to be taken into account, however, that the prismatic coefficients of the models 4770C and 4770Dare higher than the prismatic

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knots 4770 4770A 4770B 4770C '4770D 4770E 4770F 4770G 47.7014 4770J 4770g

13 100 94.5 95.3 100.0 98.9 91.7 89.1 94.0 100.9 90.8 88.2 14 100 95.0 95.4 101.0 .99.2 91.2 88.7 93.4 100.9 89.8 87.2 1.5 100 95.0 95.3 101.4 99.1 91.1 87.9 93.1 99.5 89.1 86.6 16 lOO 94.1 94.9 101.0 98.4 90.9 87.6 93.0 98.7 88.9 86.5 17 100 94.1 94.9 lO11 98.5 90.7 87.9 93.5 98.5 89.4 86.9 12 13 14 15 16 17 18 19 20 12 14 15 16 17 18 19 20

Speed in knots Speed in knots

Table VI. Percentages C for the loaded condition.

coefficients of all other models investigated; further-more, the L/B ratio of model 4770D is lower than those of the other models (see Table I).

These differences have a negative influence on the re-suits of both the models 4770C and 4770D.

Comparing the results of ship model 4770E to H, it is shown in Table VI that model 4770F has a favourable performance, being about 13% better in resistance than the basic form, model 4770. Obviously, the smallest angle between the bilge diagonal and the base line is the best., i.e. both waterline flow and buttock flOw are

im-portant for these hull forms. It may be that at larger

angles between bilge diagonal and base line, the water-line flow is hindered,leading to larger resistance values (Tables V, VI). Ship model 4770H with elliptical side and bottom plating is shown to be equal in resistance to the basic forni. The version can be improved somewhat

by adopting a sloping bilge.

Comparing the results of the ship models 4770F,

4770J and 4770K, the series with the systematically varied "gondolas", it is obvious that ship model 4770K, having the thinnest "gondola", shows the best perfor-mance, viz: about 15% better than the- basic ship model. Table VII presents the PE values of the configurations

Table VII. Percentages PE for the ballast condition.

Table VIII. Percentages CE for the ballast condition.

tested at the ballast condition, given in percentages of the corresponding magnitudes of the basic model 4770. For the same reason as explained for the loaded con-dition, Table VIII presents the resUlts of the ballast condition in percentages based on the Admiralty coefli-cient CE.

The values presented clearly show the gain in resis-tance of model 4770A over the conventional basic mod-el 4770 at the ballast condition too. The sharp bilge of model 4770B results in a rise of the resistance by about 2.5% compared with the rounded bilge of model 4770A. The series with the different "gondolas" show, com-pletely contrary to the results in the loaded condition, that ship model 4770J with the thick "gondola" has the least resistance, even less than the resistance of ship model 4770J with the thin "gondola". The moderate "gondola", ship model 4770F, is clearly the worst con-fiurátion in these series, but it is still about 3% better than the basic form, whereas the best of the series is about 11% better than the basic form.

However strange these results may seem, they are completely confirmed by the results of the propulsion and flow visualization tests as-will be seenin section 4.2

and 4.4.

-4.2 Propulsion and propulsion factors

Self-propulsion tests were carried out at a loaded draft of 24.23 m with all model configurations.

The results are given in Fig. 11 over a speed range of 13 to 18 knots.

In the ballast draft of 7.90/11.00 m, self-propulsion tests were carried out with the models 4770, 4770A, 4770B and 4770F, 4770J, 4770K The results are shown in Fig. 12.

To calculate the propulsion factors, the propeller was tested in òpen water. Fig. 13 shows the open water test results of the propeller used for the basic model and the simplified configurations. --- -

-The propulsion factors for the basic model combined with the simplified forms in the loaded condition are presented in Fig. 14 For the ballast condition the pro-pulsion factors are presented in Fig. 15.

Table IX presents the PD values at the loaded

condi-V

in

L Sho Modél

knots 4770 4770A 47703 4770C 47700 4770E 4770 4770G 4770H 4770J 4170K

1-3 100 105.9 105.2 102.5 101.2 109.1 1123 106.1 99.3 110.4 113.3 14 100 105.5 105.1 101.4 100.9 109.7 112.9 106.8 99.3 111.6 114.6 15 100 105.5 105.2 101.2 101.0 109.9 113.9 107.5 100.6 112.5 115.3 16 100 106.4 105.5 101.5 101.6 110.1 114.3 107.6 101.5 112.7 115.5 17 100 106.3 105.6 101.3 101.5 110.2 11-3.8 106.9 101.5 112.0 114.9 V in Ship Model knots 4770 4770A 477DB 4770F 47703 4770K 14 100 91.3 92.9 94.7 87.8 88.1 15 100 91.8 93.9 95.4 88.7 89.6 16 100 92.3 94.4 95.6 89.1 90.4 17 100 91.1 94.2 94.7 89.-3 85.9 18 100 90.2 93.3 92.9 89.2 89.1 V in Ship Model -knots 4770 4770A 4770B 4770F 47703 4170K. 14 100 108.9 105.2 90.6 97.5 95.3 IS lOO 107.6 103.4 88.0 94.4 92.9 16 100 107.4 102.0 86.7 92.6 91.2 17 100 106.3 101.2 86.7 92.1 91.0 18 100 105.7 100.0 86.3 93.0 91.5 12

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4770 H 700 500 300 I-inn 4770 K o n 100 0.7 06 05 0 12 13 14 15 16 17 Speed in knots

Fig. 11 DI-IP diagram loaded condition. 100 50 18 V 20

z

0.6 13

Ship No Line Ship No

770 4770 770 A F 770 B 4770 J 19 20 13 14 .15 16 17 18 Speed in knots 12 18 12 13 14 15 16 17

12 13 14 15 16 17 18

Speed in knots

19 20

Fig. 12 DHP diagram ballast condition.

12 13 -14 15 16 17

Speed n knots

0 01 0.2 03 04 05 0.6 07 0.8 09 10

Speed coefficient J

Fig. 13 Open water characteristics. Propeller No. 4344.

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Yke fraction We (taylor) Advance coefficient - Relative rotative efficiency

Table ¡X. Percentages P0 for the loaded condition.

Table X. Percentages CA for the loaded condition.

tion of the models 4770A to4770L as percentages of the P, values of model 4770, which are assumed to be 100%. To eliminate the effect of differences in displacement, Table X gives a comparison on base of

A213. V3

CA

-From Table X, it can be concluded that model 4770A is about 1% better in required power than the basic model 4770 and model 4770F is only 1'/2%worse than the basic

model.

The thin «gondola" configuration 4770K is shown to have about the same performance as the basic model and is soriiewhat better than the moderate "gondola" configuration 4770F. The thick "gondola" 4770J, how-ever, is shown to be 8% worse than the basic model, thus about the same amount with regard to the thin 'gon-dola" configuration 4770K. As the difference between the thin and thick 'gondola" amounts to some 2.5% in resistance, there must be a considerable difference be-tween the total efficiency n0of these configurations.

Taking into account the favourable performance in re-sistance of the simplified configurations over the

con-16

PD

ventional basic model, the performance in required

power is rather poor.

Obviously, the total efficiency n0 has dropped con-siderably.

results in loaded draft of the resistance and self-propul-sion tests, including the propulself-propul-sion factors, of all ship models at a speed of 16 knots are presented in TabliXI. The values show that the thrust deduction fraction z of model 4770A to D is lower than the z-value of the basic model; however, the wake fraction weis considerably

lower. The combined effect results in a drop of the hull efficiency nHfrom 1.83 for thè bisic model to aböût 1.4

for model 4770A to D. Owing to a smaller propeller load of the simplified ship forms (smaller wake) and henàà, lar-ger advance coefficients J, the open water efficiency n0 is somewhat higher than of the basic model, while the rela-tive rotarela-tive efficiency R is somewhat lower, which re: suits in a higher value of the propeller efficiency behind ship n8, viz., 0.37 for the basic model and about 0.45 for the simplified designs.

As the loss in hull efficiency n11 is not compensated by the gain in propeller efficiency behind ship n8 the total

r

I!

il

For further analysis of this phenomenon, a review of the

Ii

I

V

in

Ship Model

knots 4770 4770A 47703 4770C 47700 4:70E 4770F 4770G 4770M 4770.3 4770K

13 100 98.9 103.9 108.5 109.2 103.3 101.2 108.7 117.7 110.0 100.8 14 100 99.3 102.5 107.6 108.6 104.0 101.5 107.8 115.8 109.7 100.7 15 100 99.0 101.9 107.2 107.7 104.6 101.6 107.7 114.1 108.9 100.7 16 100 99.2 103.1 107.4 107.0 104.8 101.7 107.1 113.8 107.9 100.9 17 100 99.5 104.4 107.8 108.1 105.8 101.5 107.5 113.5 107.2 101.2 V in Ship Model

knOts 4770 4770A 4770B 4770C 47700 4770E 4770F 4770G 477011 4770.3 4170K

13 100 101.3 96.3 94.4 91.7 96.8 98.9 92.1 85.1 91.0 99.1 14 100 100.9 97.9 95.1 92.1 96.2 98.5 92.8 86.4 91.3 99.1 15 100 101.3 98.3 95.5 92.9 95.7 98.5 92.9 87.8 92.1 99.1 16 100 100.9 97.2 95.3 93.5 95.5 98.1 93.3 87.9 92.9 98.9 17 100 100.6 96.1 95.0 92.6 94.6 98.3 93.1 88.3 93.5 98.7

11

j

I

Table Xl. Summary of resistance and self propulsion tests at 16 knots, loaded draft.

Tljijst duction fraction t Hull efficiency _i/h Open water efficiency 7J

17

Denomination ship Model

4770 4770k 47708 4770C 47700 4770E 4770F 4770G 4770H 47702 4770K in tons 345.86 325.47 328.39 349.40 340.31 314.48 302.83 321.70 341.35 307.55 299.15 in HP 37958 35720 36040 38346 37349 34513 33236 35306 37462 33754 32832 T in tens 431.14 385.02 392.70 412.56 412.56 395.91 382.45 401.67 424.09 397.32 374.13 in HP 56141 55713 57905 60317 60066 58827 57105 60152 63864 60596 56646 n0 0.676 0.641 0.622 0.636 0.622 0.587 0.582 0.587 0.587 0.557 0.580 018S 0.151 0.153 0.157 0.157 0.146 0.143 0.148 0.150 0.150 0.138 10 K0 0.193 0.168 0.172 0.172 0.172 0.161 0.159 0.163 0.163 0.172 0.155 .7 0.242 _{0.322 0.314 0.309} 0.309 0.338 0.344 0.332 0330 0.318 0.355 t 0.198 0.155 0.164 0.153 0.175 0.206 0.208 0.199 0.195 0.226 0.200 we 0.561 0.390 0.401 0.404 0.405 0.337 0.332 0.349 0.339 0.386 0.306 1.829 1.386 1.396 1.421 1.387 1.198 1.186 1.230 1.218 1.260 1.153 n8 0.370 0.462 0.446 0.447 0.448 0.489 0.491 0.477 0.482 0.442 0.503 n0 0.351 0.443 0.435 0.429 0.429 0.459 0.463 0.453 0.451 0.438 0.474 1.053 1.045 1.024 1.042 1.045 1.067 1.059 1.054 1.068 1.008 1.062 05 o

-

4-05 Gd

i1iiiL:

o e-12V13 14 15 16 17 18 io L e. In

---===

lo C V 13 02 nl

4770-40A '.. 04 03

-r.

4770-4770F 4770.J

4770k

-

---12V13 14 15 16 17 18 ti lo I. F-1.1 I. F --S'

--12V13 14 15 16 17 18 19 to 9*,Lè*

4770-4770A 477o---s

L.

-t0 05 n

4770-477°c 4770k 12V13 14 15 16 17 18 19

ni--.5---p, 04 n3 -) f" 12V13 14 15 16 17 18 8

Wale fraction

(n)

An efficient J

Re4ative rotative efficiency _lJr Fig. 15 Propulsion factors ballast condition.

efficiency fl( of the simplified forms, model 4770A to D, is lower than for the conventional design, viz., flß = 0.641 for model 4770A and 0.676 for model 4770.

The same effect can be seen for model 4770E to H; it must be noted, however, that the thrust deduction frac-tion t is about the same as for the basic model, while the wake value w has dropped more than for model 4770A

to D. This results in a very low hull efficiency ng.

Though the n8 value has risen the total efficiency nD, being the combined effect of nand n8, is very low com-pared with the uD for the conventional model.

The thin "gondola" configuration 4770K shows about the same propulsion factors as the moderate "gondola" configuration 4770F. The thick "gondola" configuration

is shown to have the highest effective wake of the

models 4770E to K. Though the thrust deduction frac-tion t has also risen, the hull efficiency is the highest for the models 4770E tot 4770K. However, as the efficiency behind ship n8 is the lowest of all models investigated, except for the basic model, the total efficiency is also the lowest.

Table XII presents the PDvalues for the ballast condi-tion of the models 4770A, B, F, J, K in percentages of the PD values of model 4770, which are assumed to be 100%. Table XIII gives the same comparison on base of C4.

Contrary to the results at the loaded condition, the re-quired horse power PD of the simplified model 4770A is considerably lower than for the conventional hull. Be-cause of the sharp bilge of model 4770B, the gain in PD is reduced, especially at the higher speeds.

The "gondola" configurations show remarkable re-sults, as was found for the resistance. completely con-trary to the results in the loaded condition. The thick "gondola" 4770J needs aboutle/o more power than the

basic model, whereas thethin "gondola" 4770K needs about 9% more power. The moderate "gondola" 4770F, however, needs about 13.5% more power than the basic model and, consequently, is the worst of the "gondola" configurations.

For a better understanding of the results in the ballast condition, Table XIV presents a summary of the results of all models investigated at a speed of 18 knots. The Table demonstrates the differences in total

effi-Table XII. Percentages P0 for the ballast condition.

Table XIII. CA values in percentages. Ballast condition.

Table XIV. Summary of resistance and propulsion test results at ballast condition - speed 18 knots.

ciency. This is caused mainly by the differences in effec-tive wake W and, to a smaller extent, by the differences in thrust deduction fraction t, resulting in great differen-- ces in hull efficiency ng. Although the efficiency be-hind ship n8 gives higher values for the simplified forms over the basic form, the drop in hull efficiency can not be compensated for, thus resulting in a low total effi-ciency for the simplified forms.

4.3 Wake measurements

Wake measurements were carried out for the models 4770, 4770C, F, J and 4770K in the loaded condition. The speed at which the tests were carried out corre-sponds to 15.80 knots for all models except for model 4770C, which was tested at a speed corresponding to 14.70 knots.

The circumferential distributions of the axial, tangen-tial and radial velocity components are presented in Fig. 16, the lines of equal axiál velocity (dimensionless) and the transverse velocity components are presented in Fig.

17 and 18 respectively. -

-From the circumferential distribution of the axial ve-locity components (Fig. 16), it can be concluded that, at almost all radii, the value V/ V is lower for the basic model 4770. This means that the basic model has the

highest wake. This is also demonstrated in Fig. 19,

i

k

L

k

R

V in Ship Model knots 4770 4770A 477DB 4770F 47703 4770K 14 100 107.6 105.8 104.2 113.0 111.6 15 100 107.1 104.6 103.4 111.7 109.5 16 100 106.5 104.1 103.1 111.3 108.6 17 lOO 107.8 104.3 104.1 111.1 109.3 18 100 108.8 105.4 106.2 111.0 110.2

Denomination Ship Model

4770 4770A 47703 4770F 47703 4770K Rr in tons 295.12 266.20 275.29J274.08 263.36262.84 in HP 36438 32867 33989 j 33839 32Sl6 32452 T in tons 380.53 329.28 346.58 1372.84 352.98 347.86 P0 in HP 48963 45512. 0.744 0.722 48076 55868 0.707: 0.606 52112, 52521 0.624! 0.618 KT 0.181 0.151 0.156 0.142 0.146! 0.131 10 K0 0.196 0.173 0.178 0.161 0.169 0.148 J 0.241 i 0.314 0.301! 0.343 0.326 0.373 t 0.224 0.192 0.206 0.265 0.254 0.244 w 0.631 0.510 0.526 0.414 0.465 0.359 2.100 1.650 1.674 1.254 1.395 1.179 rIB 0.355 0.437 0.422! 0.483 0.447 0.525 0.350 0.435 0.421' 0.463 0.447 0.488 1.012 1.006 1.002 1.049 1.001 1.075 V. in : -. --. Ship Model

--knots 4770 4770A 477DB 4770F 47703 4770E

14 100 90.3 93.4 108.9 101.6 103.1 15 100 91.3 95.0 112.0 105.2 105.7 16 100 91.4 96.3 113.8 107.1 107.7 17 100 92.4 97.1 113.9 107.6 107.9 18 100 93.0 98.2 114.1 106.4 107.3 18

r

I

k

k

i

i

i

I

i

R:1500 R: 2500

where the nominal mean axial wake fractions are presen-ted for all models in the loaded cöndition. This Figure further shows that the version wih the thin "gondola" has the lowest wake fthe simplified configurations.

Fig. 16 also shows that all simlified configurations have deep peaks oflow axial velocities in the 12 o'clock position for the radii between about R=5000 mm to

\\

J-.--,-o 05

05

Fig. 16 Circumferential distribution of Vt/V. V,/V. V,JV. loaded condition.

R = 5500 mm. Ship model 4770K, the thin "gondola" configuration, shOws the narrowest peak, but not as deep as the oiher configurations.

The gradient dV/d9 is at these radii larger for this type of ship than for a ship with cônventional lines.

The wake pattern behind the. conventional model 4770 (Fig. 17), compares reasonably well with those of

19 1.0 05

f

0gree5 45 90 135 10 2 I I... 05 \3 I -_47?O . 4770C -£T?VF 47J

----47K -05 00ejres 45 90 135 1.0 o 51> -05 I I I..

o'

'.

L

1 1. 0Deee 45 90 135 180 1,0 0Derees 45 90 .135 180 19 05, 00ègrs 45 90 135 C R4500 R: 5000 R: 5500 .05 00egee 45 135 R'3500 I I I

20 30 030 030 40 0.50060

'-

020 4.20 b2.

IM

D M.4770 M.4770C M4770F

Fig. 17 Lines of equal V,/V, loaded condition.

50 60 070 80 090

1000 80° 1200 600 M 4770 140o 0160° 170 150 40° o 30 20 o 10 120o 1800

R:0O

Roop R4500 R:2,00 R 1500 o o R350Ò 1O0 800 0

T 200

M.4770J 120 M. 4770 C

/ff4'i

o 0 170 160 150 o o 40 o o 20 o o 3500 25O0 1500 0 leo

Vector Length

i corresponds to

.0.1

Fig. 18 Transverse veJocity components V,,/V. loaded condition.

:5500 :5000 R:4500 o R 3500 R:2500 R: 1500 o 80 o O 0 170 180 160 i60 0

11ì

"I

o 40

ai

o 20 o

l44770F

21 R5500 R5000 -4500 1700 1800 o 0 150 150 140e o 100 R:5500 R50o0 R:4500 R: 3500 R:2500 R: 1500 o

similar ships, what is striking is the pronounced bilge vortex of model 4770, which is much less for the simpli-fied forms.

In the transverse velocity components (Fig. 18) the

existence of the bilge vortex at model 4770 is also

shown. Furthermore, it can be concluded that the

oblique flow is more pronounced in the simplified

forms.

Wake measurements were carried out with the mod-els 4770, 4770F, J and K in the ballast condition at a speed corresponding to 18.20 knots.

The circumferential distributions of the axial, tangential and radial velocity components are presented in Fig. 20, the lines of equal axial velocity (dimensionless) and the transverse velocity components being presented in Fig. 21 and 22 respectively.

lt can be concluded that, for the basic model 4770, the inhomogeneity of the circumferential distribution of the axial velocity components is smaller than in the loaded

condition.

The simplified forms show, analogous to the loaded

condition, a peak in the 12 o'clock position.

Looking at the radial distribution of the axial velocity components (Fig. 23) the almost homogeneous distribu lion of the basic model is clearly demonstrated.

4.4 Flow visualization

Flow visualization tests were carried out for a limited number of models, viz.:

- 4770E, F, G, H, J, K in the loaded condition. - 4770F, J, K in the ballast condition.

lathe loaded condition, the speed at which the test were carried outcorresponded to 15.8 knots; the results are presented in Fig. 24 to 27 for the simplified configura-tions.

Fig. 28 and 29 present the results for the ballast condi-tiön of the simplified configurations; the corresponding speed at which these tests were run was 18.20 knots.

The Figures for the simplified forms 4770E to 4770H in the loaded conditionshow that at allmodel configura-tions in the region above and just in front of the

propel-il

j

v

\.

\ \

\\

\

\

\\\

_\\

\

SuD No Lire .

I,.

-- I S 0.9 08 07 06 04 0.3 02 0.1

o.

I-0

47t0_. 4770e 4770F

---4770J 4770 K

\\

_{\ \}

\

u,

Wm403

ed

---.-_--___

-

-

'S-1.1 lO

\

_\

'S

WrnC1t

.'

\

SS.

'N\

N

--S.--

.

-I

.1

I onR 0.1 02 03 04 O. 06 0.7 0.8 09 22

rn

Fig. 19 Radial distribution ofWloaded condition.

Í

I

R 1500 1.0 __,._J_..__ -1 05 o 05 -05 0.5 0 R450O 45 Rr2500 1,0 05 o 05 o -05 05 o 45 90 135 R=5000 R-3500 .0 05 0.5 05 o

-05o0. 45

R-5500

Fig. 20 Circumferential distribution of Y./V, 11,/V. 11,/V. ballast condition.

90 135 23 1.0 o

.

I ----s..

-..

:''

o

N

.0Ders 45 90 135. 10 -. 9.ONa 4770 1w,. 4770v 4770 J 477fl K o

\--45 90 135 10 TO0eqrs 45 90 135 180

24 M.4770 M.4770F PROP AMFTFR 060 0 05 0.60 30 040 50 60 70 080 o 100

Fig. 21 Lines of equal V/ V. ballast condition.

o 120 o 80 o PROPOIAMETFR 0.6 0.90 080 M.4770J 140o 150 300 o 20 M..4770...

00

o 0 170 160 o 180o 40 o 60 70 080 90 R: 55 00 R:5000 R;4500 R: 3500 R:2500 R: 1500

O 120 R O 140 M. 4770F o 170e 1800 160 150 200 10° oo R :5500 :5000 :4500 R: 3500 40 o 30 ₀ 20 M. 4770 J

Wctor Length of ii corresponds to

Fig. 22 Transverse velocity components V,,f V, ballast condition.

o 10 _oO

Fig. 23 Radial distribution of W ballast condition.

1400 160° 170° 180° 40° M.4770K o 30 20 o o :5500 R5000 :1500 R: 3500 R: 2500 :1500 25 ..

'.'\

_....

'N

\

SPÚp NO. Lire s'.... s.. -I _09 _0.6 _0.2 08 04 4770 477Q F 4770 J 4770 K x'.. .

\.

J

mnr0 493

N

\wme93

\

-I I

ifl329

I s

\

\

\

_\

%._

\

J o 01 02 03 04 05 06 0.7 0.8 09 10 tI O o 140

E1l1j3...I

170° 180° 1500 =5500 5000 R =4 5 00 R3500 Rr2500 :1500

o' -.1 I'

i

_iiI I f -.1 -.1

o

C)

\

tfl!

'\t

kk b -4 -'j

o

11

\ \

_i

i f. i J

;'k

ti I

I

i I! P P

ii P

i, V ! P P! V P ! P.,

II ILl i. 1ttD i

ik

vi9 t:

V

t,

-I---r

il

¿I

i

Øtl

4 I ' 1' gJI V'

e

w

i t

M4770J

M 4770 F M 4770 K

M4770J

_-i .,..t

M 4770F

-

L---Fig. 26 Flow visualization. Speed 15.8 knots. Draft 24.23 m. Without propeller.

t

- ..-. ...

-.

.-e---t

I

I

t

p

i

t'

I

M 4770 K

Fig. 27 Flow visualization. Speed 15.8 knots. Draft 24.23 m. Without propeller.

I

R

28

i

I

M 4770J M 4770 F M 4770k M 4770 J M 4770 F

L.----s--

iT-.---M 4770k

Fig. 28 Flow visualization. Speed 18.2 knots. Draft 7.90/11.00 m. Without propeller.

-- r

Fig. 29 Flow visualization. Speed 18.2 knots. Draft 7.90/11.00 ni. Without propeller.

1er, flow separation occurs in the condition without pro-peller. This phenomenon is markedly affected by the running propeller. There was no significant difference between the models 4770E to H.

The results of the "gondola" configurations 4770F, J and 4770K in the loaded condition show that the most voluminous "gondola" has the heaviest flow separation, whereas the less voluminous "gondola" showed the

smallest flow separation.

In the ballast condition the most voluminous "gon-dola" 4770J showed to have the least flow separation,

whereas the less voluminous "gondola" 4770K was

slightly worse. The moderate "gondola" 4770F, how-ever, clearly shows the heaviest flow separation. These results fully confirm the results of the resistance and propulsion tests with these models.

5 Comment on the results

The discussion of the results, as presented in section 4, is based upon the normal analysis of the results. It might be argued, however, whether this will lead to a better understanding of the phenomena. From table XI, it can be concluded that for the loaded condition, the thrust deduction fraction us about the same (0.200-0.2 10) for the basic form 4770 and the models 4770E to K, whereas z is significantly lower (0.160) for the models 4770A to D. The effective mean wake fraction w, is highest (0.560) for model 4770 - the basic form -, lowest (0.310-0340) for the models 4770E to 4770H and model 47701( A mean value of 0.400 is found for the models 4770A to 4770D. The thick "gondola" version 4770J tends to the mean values with a w, of 0.390.

The tandW,values result ma low hull efficiency nHfor

the model 4770E to K (1.130-1.260), a mean value for the models 4770A to D (1.400) and a high value for the basic form (1.800).

For the ballast condition the following conclusions can be drawn from Table XIV. Here the models 4700A and B have also the lowest t value (0.200), the basic model 4770 shows a mean value (0.220), whereas the models 4770F, J and K have the highest value (0.250). The effective mean wake fraction is highest (0.63) for the basic model 4770, lowest (0.35-0.4 1) for the models 4770F, J, and K, whereas the models 4770A and B show a mean value of about 0.51. The tandW,values result in a low hull efficiency nH(l.lS-l.4O) for the models 4770F, J and K, a mean value for the models 4770A and B (1.60)

and a high value for the basic form (2.10).

As stated above, the loss in hull efficiency can not be compensated for, neither by the gain in open water effi-ciency, nor by the relative rotative efficiency. So, the simplified models show to have a rather poor total effi-ciency compared with the basic model.

The above mentioned analysis is based, in fact, on the

total efficiency D, the thrust deduction fraction r and

the effective mean wake fraction w,.

The main problem, however, for the "pram" type mo-dels 4770E to K, in the loaded condition, is that the resis-tance is much lower than for the basic form 4770, but the interaction between propeller and ship's hull turned out to be very unfavourable. The same can be seen for the models 4770A to D, but to a smaller extent.

In the ballast condition too, the models 4770F, J, K and L show a very unfavourable interaction. Based on the results ofthe versions 4770A and B, they show an in-teraction of the same magnitude as the basic model.

Some idea of the interaction can be obtained by com-paring the nominal mean wake fractions wand the effec-tive mean wake fractions w,.

Table XV shows the nominal and effective wake frac-tions, as well as the thrust deduction fractions for the loaded and for the ballast condition.

It appears that, in loaded condition, nominal and

effective mean wake fractions are about equal for the basic model 4770. This indicates that flow separation will occur owing to the propeller action, otherwise the

effective mean wake fraction would be smaller than the nominal mean wake fraction.

In ballast, the propeller may cause a significant separa-tion, as a result of which the effective mean wake frac-tion is higher than the nominal fracfrac-tion. Since, in the ballast condition, the stern profile above the propeller is ot Of the water, the separation zone must be in front of the propeller. Furthermore, it can be concluded that the interaction is larger in ballast than in loaded condition, which is confirmed by the thrust deduction fraction.

Ship model 4770C shows an effective wake fraction, which is smaller than the nominal wake fraction. It may be expected that separation in 12 o'clock position in front of the propeller is already present during the resis-tance test, and is significantly improved by the propeller action. This may also lead to a low thrust deduction frac-tion.

In the loaded condition, the effective mean wake frac-tion is significantly higher than the nominal mean wake fraction for model 4770K and higher for model 4770F.

Table XV. Nominal and effective mean wake fractions, thrust deduction fractions.

w

slttp

Model

Condiion

Loaded 16 knots - Ballast 18.0 knots

t__ w w t w w e e 4770 0.198 0.568 0.561 0.224 0.515 0.631 4770C 0.153 0.432 0.404 - - -4770F 0.208 0.306 0.332 0.265 0.393 0.414 4770J 0.226 0.403 0.386 0.254 0.493 0.465 4770K 0.200 0.213 0.306 0.244 0.329 0.359 30

P1

w

p

I

p

I

I

ii

p

p

'z

p

I

'I

I

p

This means that flow separation must be generated or increased by the propeller actioñ. From the tuft tests withoutand with propeller, ¡t appeared that some separa-tion in the zone above the propeller was present and by the propeller operation it became significantly worse. lt is plausible that, for modél 4770J, the effect of the con-traction of the incoming flow at the propeller due to tlie propeller action is larger than th stimulation of flow-breakdown.

The ballast condition also shovs an effective mean wake fraction higher than the nominal mean wake frac-tions, except for model 4770J, sO interactión is caused by the propeller action. This is clearly demonstrated by the tuft tests.

To improve the propulsive performance of the 'pram" type afterbody further research irto the resistance and the interaction between the propeller and ship's hull is necessary.

6 COnclusions

- The investigations

have shown that

simplified "pram" type afterbodies can be designed with an im-provement in resistance ofabout 10% with regard to ä conventional form, the resistance of whiëh was con-sidered to be satisfactory.

The best simplified designsare about equal iñ propul-sive performance with regard to the conventional hull in the loaded condition. In the ballast condition, how-ever, a gain in required power of some 7% is obtained with the "pram" type hull 4770Ä with regard to the conventional hull 4770. Compared with the conven-tional hull the simplified versions all show the need for more required power in the Ibällast condition.

- The simplified hull forms shOw an interaction between the ship and the propeller which is completely differ-ent from that of the convdiffer-entional form: ship models 4770A to D have lower wake fractions, resulting in a lower hull efficiency than the conventional form, whereas ship models 4770E to K show thrust deduc-tion fractións equal to that of the convendeduc-tional hull form and much lower wake fractions, resulting in very low hull efficiencies.

As a result of the low hull efficiency, the total effi-ciency Dof the simplified "pram" type is very low, re

suiting in a relatively poor propulsive performance. - The simplified "pram" type hull forms lead to a peri-pherally more homogeneous nominal wake field with a prOnounced wake peak at 12 o'clock position.

- Thrust deduction fractions, nominal and effective

mean wake fractions, in loaded and ballast drafts, in-dicate the interaction between propeller and ship's hull and can give insight into suppression of flow separation in front of the propeller by the propeller and propeller generated flOw separation above the propeller.

- More systematic research is necessary to study the possibilities for improving the propeller-hull interac-tion.

- The design of a "gondola" for simplified hull forms needs special attention in order to avoid a poor perfor-mance, especially in the ballast condition.

Referencés

-1. KiSs, R. K., Aspect of simplified hull forms. Past, present and fùture. SNAME, San Diego, section February. 1972.

PUBLICATIONS OF THE NEtHERLANDS MARITIME INSTITUTE

Monographs

M I

fltsiniulation with cônventional ships and seagoing tug/

barge combinations, Robert W. Bas, 1976.

M 2 Ship vibration analysis by finite element technique Part

III: Dampiñg in ship hull vibrati5ns, S. Hylarides, 1976.

M 3 The impact of Comecon mailtime po1iy on teñi shipping, Jac. de Jong, i 976.

M 4 Influence of hull iñclination and hull-duct clearan on performance, cavitation and hull excitation of a dúcted

propeller, Part I, W. van Gent and J. van der Koóij, 1976.

M 5 Damped hull vibrations oía cargo vessel, calculations and

measurements, S Hylarides, 1976.

M 6 VLCC deckhouse vibration, Calculations compared with

measurements, S. Hylarides and R. van de Graaf, 1976.

M 7

Finite element ship hull vibratiòn analysis compared

with full.scale measurements, T. H. Oei, 1976.

M 8 Investigations about noise abatement measures in way of

ship's accommodation by means of two laboratory facili-ties, J. Buiten and H. Aartsen, 1976.

M 9 The Rhine-Main-Danube connection and its economiçal

implications for Europe. Jac. de Jong, I 976.

M IO The optimum routeing of ptpes in a ship s engine room C. van der Tak and J. J. G. Koopmans, l977

M 11 Full-scale hull pressure measurements on the afterbody of the third-generation containership s.s. "Nediloyd Delft", R. A. P. J. Schulze, 1977.

M 12 Cavitation phenomena and propeller-induced hull pressure fluctuations of a third-generation containership, A. Jonk and J. van der Kootj, 1977.

M 13 Hull vibration measurements carried out on board the third-generation containership s.s. "Nedlloyd Delft",

R. A. P. J. Schulze, 1977.

M 14 Hull vibrations third-generation contaiñership, S. Hylari-des, 1977.

M 15 Influence of hull inclination and hull-duct clérance n

performance, cavitation ànd hull excitation of a dücód

propeller, Part 11, J. van der Koàij and W. van den Berg, 1977.

M 16 The determination of the acoustical source strength of propellers of two merchant vessels. A. de Bruijn, 1977. M 17 Experiments on acoustic modelling of machinery

excita-tion, J. W. Verheij, 1977.

M 18 The effect of a pram-type aftbody shape on performance,

cavitation and vibration characteristics of twin-screw dredgers. W. van den Berg and J. van der Kooij, 1977.

M 19 Investigations into the effect of model scale on the perfor-mance of two geosim ship models, Part I: Flow behaviour

and performance in calm water,, A. Jonk and J. van de

Beek, 1977.

M 20 Investigations into the effect of model scale on the

perfor-- man of two geosim ship models, Part H: Behaviour and performance in waves, M. F. van Sluijs and R. J.

Domrnershuijzen, 1977.

M 21 A Tale of Eight Seaports. Jac. de Jong, 1977.

M 22 Aniiivtigation iñio the difference betwe.en nominal and.

effective wakes for twO twin-screw ships, M. Hoekstra, 1977.

M 23 Residue calculation method forchemical tañkers, H. J. A. SchiiUrrnanS and J.. G. M. Schilder, 1978.

M 24 Acoustic source strength measuremênts of a ship propeller cavitation for twO cargo mOtor vessels, A. DE BRUUN, 1978. M 25 - MOdel experiments for the determinatiOn of the acoustic

source strength of ship propeller cavitation of s.s. "Abel

Tasman", A. de Bruijn and A. G. P. Versmissen, 1978. M 26 Sound transmission into a ship's cabin built of steel plate

sand wich panels, J. Buiten, M. J. A. M. de Regt and J. W. Verheij, 1979.

M 27 Investigation into noise exposure of engine room per-sonnel aboard m.s. "Trident Amsterdam", J. Buiten and

H. Aartsen, 1979.

M 28 Thê vibratory behaviour of a rotating propeller shaft

Part I, Theoretical analysis, A. W. van Beek.

M 29 Thè vibratory behaviour of a rotating propeller shaft,

Pan II, Experimental analysis, L. J. Wevers, 1979. M 30 Thê effect of a floatingfloor as an acoustical measure on

board-a ship, J. Buiten and M. J. A. M. de Regt. 1979. M 31 Emulsification of chemical tanker slops and dimensioning

of slop's discharge ports, H. J. A. Schuurmans, C. A. M. Oudshoorn, A. P. Mahieu, F. H. J. Bukkems and H. van der Poel, 1979.

M 32 Sound transmission to a ship's cabin constructed with

flbre-reiriforcêd calcium silicate panels, J. Buiten and

M. J. A. M. de Regt. 1979.

M 33 Homogenization of chemical tanker slops, H. J. A. Schuùr-mans, F. H. J. Bukkems and J. G. M. Schilder, 1979 M 34 Chemical tanker cleaning by ventilation, H. J. A.

Schuur-mans and J. G. M. Schilder, 1979.

M35 Prewash procedures for chemical tankers, H. J. A. Schuur-mans and J. G. M. Schilder, 1979.

M 36 Physical and chemical properties of chemicals shipped in bulk, D. M. Brouwer, H. J. A. Schuurmans, J. G. M.

Schilder and W. Dannenberg, 1979.

M 37 Investigation into the effect of different afterbody lines of high-powered single screw ships on propeller-gene-rated hull-pressure fluctuations, A. Jonk and J. van der

Kooij, 1979.

M 38 Ship vibration state ofthe art 1979. R. Wereldsma. 1979.

Reports

R Flame cutting and one-sided mechariised MAG weld-iñg, in the vertical position, M. P. Sipkes, 1978 (in Dutch).

R 175 Vibration analysis of different propeller-duct structures,

incorporating the addedmass of the surrounding water,

A. dê Kraker, 1980.

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