Investigations into fundamental characteristics and operating performances of side thruster

(1)

A

MITSUBISHI TECHNICAL

BULLETIN MIß 010035

MITSUBISHI TECHNICAL BULLETIN No. 35

Investigations into the Fundamental

Characteristics and Operating

Performances of Side

rIlftt

May 1966

(2)

and Operating Performances of Side Thruster

Abstract

Model experiments are made on the configurations of the ducted-impeller-type side-thruster unit and performance tests of the hulls equipped wit/i a model unit are made in order to obtain a

sound basis for side-thruster design.

Manoeuvre trials are made wit/i the free-running models to visualize the possibility of efficient

ship operations by the use of side-thruster and the required capacity of the unit is estimated. Simplified considerations are made on the performance of th.e ship equipped with a

side-thruster and simplified in-ethods are proposed for the evaluation of the effectiveness of the unit.

Introduction

The installation of a lateral-thrusting-unit in a ship

has been considered to be one of the most effective

method for the automatic ship operations. However,

only few data are available at present for the practical design of a side-thruster-unit with a good performance and an appropriate power for the purpose.

In order to obtain the basic data for the design,

Mitsubishi Heavy Industries, Ltd. programmed a new project in 1962 in co-operation with the 59th Research

Committee of the Shipbuilding Research Association of Japan. Along this project, wide variety of experi-ments are conducted at the Nagasaki Experimental

Tank of Mitsubishi Heavy Industries. Ltd. Particular emphasis is laid in the programme on making clear the inter-relation between configurations of the side-thrust-er system and its working charactside-thrust-eristics, togethside-thrust-er with

the capacity of the thruster required for the typical manoeuvring.

As the first step, experiments are conducted on the

duct configurations for a definite impeller and the

systematic series tests are performed for a number of

impeller models of various particulars. Next, the

model thruster-unit is installed in the bow of the ship

models of various forms and the lateral-thrust are

measured under captive conditions, together with the

observation of the manoeuvring motion of ship models

under free-running conditions as effected by the

side-thruster-unit.

Apart from these experiments, theoretical approach

is made to the working characteristics of the unit by the four members of the 59th Rasvarch Committee of

the Shipbuilding Research Association of Japan. For

convenience a brief summary of these theoretical in-vestigations is given in the appendix of the present

report.

Series Tests on Ducts and Impellers

2. 1 Testing method

Six impeller models are made and the tests are

Director of Nagasaki Technical Institute, Technical Headquarters

Chief of Experimental Tank, Nagasaki Technical Institute, Technical Headquarters * Experimental Tank, Nagasaki Technical Institute. Technical Heaclquarters

Kanarne Taniguchi5

Kyoji Watanabe**

Hironao Kasai***

conducted foi' the case of possible combination of the duct and impeller in order to obtain a reliable data for the design of side-thruster unit with good characteristics.

Tests were conducted at the smaller towing tank. The thrust and torque of impellers inside the

simpli-fled duct unit are measured under 100% slip condition by the propeller open dynamometer. together with the measurement of the duct axial force by the swing frame specially made for it.

The principal particulars of the six impeller models are listed in Table 1. and the drawings of three impellers

are given in Figs. l'-3 together with the shape of the

boss of the controllable pitch impeller in Fig. 4. The drawing of the blades of the three-bladed im-peller model P. No. 1308-B is the same as those of the

four-bladed impeller model P. No. 1308.

The boss-length is 1.5 D. which is common to all the impeller models.

The standard duct unit consists of a rectangular box

with the dimensions of 4.25 D in draught (with some

amount of free board); 6 D in breadth and 2 D in thick-ness (D=200mm; the diameter of impeller).

A circular duct hole is bored horizontally in the

middle of duct unit with the immersion of 1.25 D at the

duct center from water surface. The diameter of the Table i P. No. D (mm) 1309 1307 1308 1322 1323 1308-B 200.00 P/D d!D 0.750 adjustable for; 0-1.3 0.300 0.400 Ae/.4d 0.5246 0.450 0.300 0.600 0.3375

Blade contour Elliptic Kaplan-type

Blade section Elliptic Aerofoil (Symmetrical)

Z 4 3

(3)

2

0.007.94... e003(

r '9 = 1 0

0.007

Fig. 1. Fixed pitch impeller (P. 1309)

Fig. 2. Controllable pitch impeller (P. 1307)

Fig. 3. Controllable pitch impeller (P. 1308) Particulars

Diameter (mm) 200.00

Pitch (const.) (mm) 150.00

Pitch ratio (coust.) 0.7500

Disc area (m2) 0.03142

Expanded area (&) 0.01648

Projected area (m3) 0.01526

Expanded area/Disc area 0.5246

Projected area/Disc area 0.4857

Projected area/Expanded area 0.9260

Boss diameter (mm) 60.00

Boss ratio 0.3000

Thick chord ratio at 0.7 R (%) 5.68

Blade section Ellipse

Number of blades 4 0.0126 0.0I8iI' 12o9 0.95 U 0.9

P-

-0,0292 ' II 0.8 04031.. 0.7 4W_______ 0.0514

II______-

0.6 00625

I

0.0736 74 " 06

'.

0.0847

s

0.3

'

03366 0.168

't

00590 0.0590 02387 00070 0,0024# r,. i.00 00l26,9i 0.95 00183 .R01! 01556

oo296Är_

. 0047' 0,2705

117ii.1F»

0.2685 0.2827 72549

j

0.4 00750 03366 0,1346 Particulars Diameter (mm) 200.00 Pitch (mm) O Pitch ratio O

Disc area (on2) 0.03142

Expanded area (m2) 0.01414

Expanded area/Disc aera 0.4500

Projectea area/Disc area 0.4500

Boss ratio 0.4 000

Blade section Aerofoil

Number of blades 4 0,0070 - - 0.0035 r,'R 1.000 501 21, 0.0393 0.95' 0,8425 '-0.9 ,_,R50 0.0297 _leu 0.8

ili36/

I Blade op 0.04101 55 0.7 _________________ 000231 049 0.5 4 S oZ'°° S '2°e 0.02509 0,4

i

0.3366 07046 o06o,/_0.o6oIs Particulars Diameter (mm) 200.00 Pitch (mm) O Pitch ratio O

Disc area (on2) 0.3142

Expanded area (m°) 0.01414

Expanded area/Disc area 0.4500

Projected area/Disc area 0.4500

Boss ratio 0.4000

Blade section NACA 16

(4)

A-A Section

0)

Fig. 4. Controllable pitch impellers

0) Duct block

(8) Swmg frame

® Impeller shaft stay

0) Impeller

0) Thrust & torque dynamometer 0) Duct bfock axial force dynamo.

0) Towing rod

Fig. 6. Fundamental test arrangement

duct hole is 203 mm, i.e.. the blade tip clearance is 1.5mm.

The shape of the duct block is shown in Fig. 5. The

corner of the duct end periphery is rounded by the ra-dius of 10 mm.

In the basic tests, the impeller revolutions are

widely changed from the considerably lower values to the possibly highest ones and their effect is examined.

The result shows there is no substantial differences.

when the results are expressed in the non-dimensional forms, for the range of the number of revolutions larger than lorps.

Thus, the results for n=15.2orps are adopted for

all the impeller tests.

Measured values and their notation are listed below together with their non-dimentional representations.

Impeller thrust Duct axial thrust Impeller torque

Total thrust

Impeller Diameter Impeller revolution

0) P. No. 1307 Blade contour 0) P. No. 1308 Blade contour 0) P. No. t 322 Blade contour 0) P. No. 1323 Blade contour

80 _45lo: 11710 35 12

UI IU

'T

1.5 118.5 lIBO 11297 o

j

non-dimensional notations representations

T (k)

C.= F (kg) CF= Q )kgm T+F (kg) D (m) n (rps

0) Prop. dynamo, shaft

0) Supporting shaft 'i pn°D° (T+F) CTF - _pnoDx Density of water p (kg. s2/m4

The following expression is introduced for the

re-presentation of the efficiency of a side-thruster.

fCTF \

r 1 (1)

2 G0

When the total thrust (T+F) becomes larger, the

3!) 31)

L_A

t Hook to swing frame

2 Duct Detachable

21) 31) AA Section Fig. 5. Duct block (Parallel wall type)

Fig. 7. Duct length series

higher fl-value is obtained under constant diameter of impeller and a definite DHP.

There is no effective work done by the side-thruster

working under 100% slip condition and it will be impossible to define the efficiency in the strict sense.

However, regarding the side-thruster as a water current generator in the duct, the efficiency can be defined by

taking the current as the effective output. The work done by the generation of the water current can be

obtained as the product of the flow-rate and (pressure

xarea), and the flow-rate and (pressurexarea) are ap-proximately equal to ','(T+F)/pA and T, respectively.

where A denotes the cross sectional area of the duct. Thus, the efficiency in the present definition is,

Tx (T+F)/pA 75 SHP

For convenience. T is replaced by T+F, and it is reduced to (1).

This efficiency value can be used as a direct measure for the comparison of the effectiveness of the different

duct system with a definite impeller. However, it must

not be used as the measure, if there are some

restric-tions in choosing the number of revolution in the prac-tical case of side-thruster design.

2. 2 Instrumentations for the tests

The arrangement of the test instruments is shown

in Fig. 6.

The box ® with a duct passing through it is hanged down from the two swing frames ®.

The impeller model is mounted at the end of the

axis of the propeller open dynamometer ® and the axial

thrust and torque of the impeller are measured with it

together with the number of impeller revolutions. The axial component of the force exerted on the duct is measured with the resistance dynamometer ® by way of the swing frame (i) and the towing rod ®.

(2f 3 T pn2Da F pn2D Q

(5)

2. 3 Test results and considerations

2. 3. 1 Series tests of duct configurations

li Effect of Bottom Immersion; 1h

The bottom immersion lb of the duct block are systematically varied as 1D, 2D, 3D while the immer-sion of the impeller is kept constant (250 mm) as shown in Fig. 6.

The test condition is as follows.

Tested impeller P. No. 1307

(The pitch is fixed at p=O.75O

1=250mm (I/D=l.25) ld=400mm (2D)

ih=200, 400, 600mm (1D. 2D, 3D)

ls=600 mm (The horizontal half breadth in the

normal direction to the duct axis) ö= 1.5 mm, R= 10mm

The test results are shown in Figs. 8 & 9.

lt is noted that the effect of the number of the impeller revolution n is almost negligible for the range of n above n=l0 (rpsL And thus, the further

tests are conducted at n=15 and 20.

The effect of bottom immersion on the C. C. C

is shown in Figs. 8 & 9.

Although, no marked change can be observed

with-in the range lb=l-.-3D, abrupt change of

the tendency might be expected for the lower value of lb.

(2) Effect of duct length: Id

The length of the duct ld, was varied as shown in

Fig. 7.

The test condition is;

Impeller model: P. No. 1307 (The pitch is fixed at Po.i=O.750)

4 0.4 0.3 u . 0.90 0.4 -. 03 'J 0.2 Ji. u - n=l5rps PN n= 20 rps 2D 1 0.10 _ID _2D _3D .750) 3D

Fig. 9. Bottom immersion series

Fig. 10. Duct length series 0.09 0.08 0.07 ' C.-0.06 'i 40 0.10 0.07 4D n 0.09 'b b, 0.08 II u 1=250mm )I/D=1.25) lb=600mm (3D) ls=600mm (3D) ld=200. 400, 600 mm. )1D. 2D, 3D) Ô=1.5mm, R=l0mm

The test results are shown in Figs. lo & Il. It is noticed that C is almost independent of the duct length, while, C0 and CF are nearly constant

for the range of ld>2D, whereas the latters increase

for the range of ld<2D.

,j-value is nearly constant for id<2D, but it has

apparent tendency to decrease for still longer length of the duct. This tendency may be explained by the increase of the friction loss at the inner-wall surface of the duct.

)31 Effect of the radius of the roundness of the duct-end

corner; R

In principle, the shape of the duct-end corner

should be determined on the basis of the extensive investigations on the ship resistance and the effici-ency of lateral thrusting.

In the present test, however, only the effect of the roundness of the duct-end corner is investigated by measuring the thrust and torque of the impeller and

the axial force of' the duct for the three different

magnitude of radius of roundness. The test condition is as follows.

Impeller model; P. No. 1307 (The pitch is fixed at po,=O.7SO)

1=250mm (I/D=l.25) ld=400 mm (2D) lh=600mm (3D) ls=600mm (3D)

(3=1.5mm, R=0, 10, 40mm, (0, D/20, D/5) The test results aie shown in Figs. 12 & 13. It is noticed that CF falls down remarkably as the radius approaches to zero. while the same tendency

can be observed in the ri-value. These results may

ID 2D

14

Fig. 11. Duct length benes

0.10

0 10 20 30

R mm

Fig. 12. Duct entrance shape series

40 5

/

----niOrps

CC ¡3/20 D/10 D P,No. 1307 (P= 0.750) -.o-..15rps

-u 13 1.1 P. No. 1307 (P.7R= 0.750) n 0 rps C) 1.0 u 0.9 IL) 20 3D 41)

Fig. 8. Bottom znnersion .6eries

o o X u 0.25 0.20 0.15 3D 0.10 0.09 0.08 0.07 0.06 0.05

(6)

0.25 0.20---ç-) 0l O. ç) PNo. 1307 1' 0 7501 C e 15 rps o - 20 rps 2 3 4 5 6 7 & 9 10 11 '3 mm 0.09 0.08 007 °-ç.. 0.06.2 0.05

he explained by the separation of flow which occurs around the sharp-edged duct-end in the upstream of the impeller.

In the range of R/D= 1/20=-1/5, CF becomes larger

and C9 and C become smaller according to the

in-crease of R, while only little variation is observed in ri-value. This results may be explained by the fact that the separation loss at the duct entrance is

minimized already at the value of R=1/20.

(4) Effect of the tip clearance; 5

The clearance between the inner-wall surface of the duct and the blade tip of the impeller is varied

in four differing values.

The test condition is as follows.

Impeller model; P. No. 1307 (The pitch is fixed at po.7=O.750)

1=250 mm (J/D= 1.25) 1(1=400mm (2D) lb=600mm (3D) ls=600mm (3D) 6=0.5, 1.5, 5.0, 10,0 mm (D/400, P/133.3, D/40, P120) R= 10 mm

The test results are shown in Figs. 14 & 15.

As shown in Fig. 14. both C and C9 are

consi-derably lowered in similar tendency by the increase of 5, while Cris only slightly lowered by the increase of 5.

Within the scope of the present test results. C.

and CQ seem to approach a certain definite value by

increasing ö. They must, however, approach C=0.233 and CQ=0.0342 at the limit of 3= co, which are

obtain-ed from the open water test results.

It is inferred that C1. approaches O at the limit

of 5= 00, and thus C1. will be simply lowered with

increasing xi. Axial distance o (Duct center) -20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 + 0.4 ± 0.8 + 1.3 + 2.1 + 3.6 + 4.8 + 5.0 + 5.8 ± 6.6 + 7.7 ± 9.0 + 10.4 + 12.0 + 14.5 + 18.7 R-R0 0 (mm) o ± 0.1 + 2.9 +40.0 (18.5R) Contracted entrance

_jljChannel cross sectional .

...area const.)

Impeller boss

Fig. 16. Tested duct with concave inner-wall

Expanded entrance / I For stata pressure ne005ery

Impeller boss

Fig. 17. Tested duct with convex inner-wall

Table 2. Deformed duct dimensions

(a) Convex loner-wall (b) Concave inner-wall

type type

(For static pressure

re-covery and widening angk) cross sectional area)(For constant channel

Diameter at duct center

203mm (ZR0) comment

to (a) and (b)

RRadius of duct section ¡?= Radius at duet center

(5) Effect of duct shape

The following two variations of the standard duct shape are tested in order to investigate the effect of

axial distribution of the cross sectional area of the duct.

Concave inner wall type duct; The standard duct is a cylindrical one with constant circular cross

sec-tion. However, a large impeller boss is situated in

the midst of the duct axis, and, therefore, the cross

s',,

Axial distance J? R O O (Duct center) 0 mm -90 0 100 -0.3 110 -1.1 120 -2.5 330 -4.2 140 -6.3 145 -7.0 150 -7.5 160 -8.2 170 -8.2 180 -8.2 190 -8.2 200 +1.0 (lO.0R)

Fig. 14. Tip clearance series

1.1 1.0 0.9

L.

P.No. 1307 1P-= 0.7501 n 20 rpo 0.0 _L r 0 10 20 30 40 1? mm

Fig. 13. Duct entrance shape series

01 23456789 10

11

4 mm

(7)

sectional area of the flow channel is cnsiderably

widened towards the both ends of the duct. There-fore, the investigation is made on the concave duct

shape. i.e. the duct is contracted towards the both end of the impeller boss in order to keep the

uni-form flow section as shown in Fig. 16 together with the off-sets of its dimensions in Table 2.

Convex inner wall type; The cross sectional area

of the flow channel is made to widen towards the both ends of the duct in order to investigate the effect of the static pressure recovery in the outlet

flow. The duct shape and its dimensions are shown in Fig. 17 and Table 2, respectively.

As is shown in the test results given in Fig. 18,

CT and C0 have largest value at the concave inner

wall type as followed by the cylindrical type and

then the convex inner wall type. In CF values, how-ever, any difference cannot be found between them, although the cylindrical type seems to have the su-periority among them. The cylindrical type has the largest ri-value among the three, while the convex inner wall type has a very small value of i.

16) Effect of guide vanes

The effect of the number of the guide vanes is investigated for the case of two- and three-guide

o Ci Co,vev

o

_i

' JLJ!

iilf'

H-!II

(ij Guide vane (n= 2) ® Duct block

® Guide vane (n= 3) ® Support bearing ® Detachable ring ) Dynamometer shalt

(a) Guide vane & axial thrust escapement

(b) Grids (Case for n4)

Fig. 19. Guide vane & grid

00

vanes for each of the ths'ee- and the four-bladed

impeller. The sectional shape of the guide vanes is shown in Fig. 19.

They are all with elliptic section with 1/3

axis-ratio. where the major axis is 60mm for the case of two guide vanes, and 40mm for the three,

respect-i vely.

The total wetted surface area and the projected area of the guide vanes in the direction of the duct center-line are identical for the two cases of

two-and three-guide vanes.

The distance between the upstream guide vanes

and those in the downstream is 90mm as measured at the innen' edges of these guide vanes. Impeller

is situated at the center of this space. The test

re-sults are shown in Figs. 20 & 21. Within the scope

of the present tests, it is shown that the effect of the number of guide vanes can hardly be found in

the measured quantities.

In comparision with the case of zero guide vanes, r is lowered by the presence of guide vanes.

The reduction of rj mainly comes from the increase of CQ.

7) Effect of grids

The effect of the grid is investigated for different number of grids; 2, 3. 4 and 5.

An example of the mounted grids is shown in Fig.

19. All the grid bars have elliptic cross sections

with 1/4 axis-ratio and their dimensions are chosen

so as to satisfy the condition of the constant total

wetted surface area and the constant total projected

area of the grids in the direction of the duct center line for each case of the grid numbers. The grid bars are fitted horizontally at the both ends of the duct in parallel to each other at an equal interval within the duct inner diameter. The section of the grid bars are chosen to be an ellipse of 60mm x 15mm

for the case of two grid bars as the standard.

Q

0.0

0.8

C

Guide vanes

Fig. 20. Guide vanes

P.Ns. 1307 (Py,e'0.750) n-=20rps

fo 0=4

P0,,0.750 n=20 t

I.z=3

Channel cross sectional area constant at guide narre center Wetted surface of the guide vanes constant

Guide vane cooss section is elliptic with 3 : t aseo

0 0 2

Gutde vanes

Fig. 21. Guide vanes

0.3

Channel cross sectional

2. Wetted surface of the

3. Guide vane cross seCtion

anew co,stanl al guide vane center

gurde vanes constant

is elliptic With 3 1 aves Cr,

Cu

0.2

e

C,

O.

PNv. 1007LPv =0 750 r Convex i,,e, wall tlpe

nc.}

0.9 iO Concave ne, Wall type

L orica ve t ql Pa, 1H nCc - C,, C Cp Conca ve r C,r Parallel q Cony., 03 52 0t-20 5 IO 05 impeller revolution n OS

Fig. 18. Duct inner-wall shape series

'=0.7501 =2O ros

PNo.1307 lPvr

(8)

0.9

0.8

t - Channel cross sectional area constant at grid center

Wtted surface of the grids constant

Grid section is elliptic with 4 t axes

- - _Grid sectiOn i

Numbers Major axis Mirrnr axis

2 6000mm t5.00mm 3 41 40mm t 0,35mm 4 31.80mm 7.95mm 5 25.84mm 646mm 1 2 Cre Ci PNo 13Ò7 lOro 075W o Qr75 Grids Fig. 22. Gridt P.9w. 1307 Pc e 07501 e = 2drps Grids Fig. 23. Grids

The test results are shown in Figs. 22 & 23. The curves of C. and CQ show slightly-decreasing

tendency with the increase of the number of grid

bars, whereas CF apparently decreases and thus

has also decreasing tendency with the increase of

the number of grid bars.

In comparison with the test results without grid bars both CT and CQ increase by the presence of

grid bars and C. decreases, whereas CTF=(CT+CF) shows almost no difference in the both cases.

(8) Effect of duct-end-wall inclination

The tests mentioned in the preceding sections are all conducted for the duct unit with vertical walls.

In the actual ship, however, it is quite probable

that the side-thruster is installed at the part of ship hull with inclined walls.

Therefore the effect of duct-end-wall inclination is investigated for the following cases.

Duct center-line length =21)

Bottom immersion below

the duct center-line = 1.5 D

Duct-end wall inclination=(90°), 750, 600

where the 90' inclination means the vertical walls.

The definition of the magnitude of inclination are

given in Fig. 24.

The test results are shown in Figs. 25 & 26. The curves of CT and C have the similar tendency of change, although they are almost constant,

where-as CF hwhere-as slightly decrewhere-asing tendency and thus r

apparently decreases with decreasing magnitude of

inclination.

2. 3.2 Impeller series tests

(1) Effect of the blade contour

The effect of the blade contour is investigated for the two differing cases; the one is an elliptic (P. No.

1307) and the other is Kaplan type (P. No. 1308). The both impeller models have the blade area ratio of Ae/Ad=0.450 and the boss ratio of dJD=0.400 in com-mon, and the tests are conducted for varied pitch

-ç) 1.0

L':

0.8 0 6r _{O -75'} LA

Fig. 24. Duct block (inclined-wall type)

P.No. 1307(Pe,e= 0.750 n=20rps

ratio at the radius of 0.7R from p=0.2 to 1.3.

The results are shown in Figs. 27 & 28.

The coefficients CT, C and CF are found to be

larger for the Kaplan type blade contour. This im-plies that the diameter of the impeller required for

attaining the equal performance is smaller for the

Kaplan type. Fig. 28 indicates that the attainable

thrust from a definite amount of power becomes

greater according to the increase of pitch within the

test range of p=O.2-.l.3 under the conditions of constant diameter and the free choice of the pitch ratio and the number of revolutions, although the increase of thrust is very small and thrust may be regarded as nearly constant for the range above

Pno'°'

The Kaplan type impeller can develop larger thrust than the other under the same

con-ditions stated above.

It should be noted, however, that in the case where there is no restriction to the diameter of the impel-ler, and the power and the revolutions are given, the comparison of the performance should be made on

the basis of some other kind of expressions. These

basis for the comparison can be obtained from Fig.

27.

(2) Fixed pitch impeller test

The test results for the fixed pitch impeller P. No. 1309 is shown in Fig. 29 (dID =0.30). The boss ratio of a fixed pitch impeller can be made smaller than

-n,

PNo. 1307 (Pern- 0,7501 n Cnr 20 rps e --.cc_____. C, o Cr _c 90 80 70 60

Wall inclination deg

Fig. 25. Duct wall inclination

t. Channel cross sectional area constant at grid center 1.0 2. Wetted surface of the grids constant

3 Grid section is elliptic with 4 :t aces

90 80 70 60

Wall inclination deg

Fig. 26. Duct wall inclination

o 0.3 X 20.2 o ca u 0.1 Q. a. ca

(9)

r

0.0 0 7 0.6 0,5 03 -0.2 0.1 0.2

Fig. 27. Blade contour

1.2 10d 0.7 0.7 ç 0.4' i- . 0.2 0.8 0 0.7 0.6 05 a 0.3 1.) i; 0.2 Li 0.1

P.No. AC/4.i t D Blade contour

P. 1322 0.3000 0.4000 Kaplan P. 1308 0.4500 0.4000 Kaplan P. 1323 0.6000 0.4000 Kapian e = 20 rs aO.1 ç-)

..---0 2 0 3 3 4 0 5 0.6 0.7 0.8 0.9 Pitch ratio at 0.75 P.Ño. P. 1308 B P, 1308 o 2ûrpo Slip 100 ç-Fig. 34

Fig. 31. Are ratio series

J

1

z _{.l. .t.I} il1) Blade contour q,/o <ta,

3 0.3375 0.400 Kaplao

4 0.450 0.400 Captan

i.,'

02 03 04 05 0.6 0.7 0.8 00 1.0 1.1 1.2 1.3

Pitch ratio atO 75

Fig. 32. Comparison of blade numbers

03 04 05 06 07 08 0.9 1.0 11 12 13

Pitch ratio at 0.7R

Fig. 33. Comparison of blade numbers

'4

P.1307 P1300 P.50. .9C hi d 04500 0,0000 04500 04000 10 Blade contour Ei ¡olio Captan

/

/4 4

n=2irpo

P

.__z

-II,

P.No. P. 1307 P. 1308 A/Al d/D 04500 0.4000 0.4500 0.4000 Blade Elliptic Kaplan contour

r'

20 tpo i

-.

-

,- \_h 20 : A 3 0.3375 4 0.4500 'Ad 'Sl 4 D 0.400 0.400 t Olade Kapan Kapan conto P,No. 1308-1308 P. B P. P.No. 1309I Po to 0.75k) o 20 ros Elliptic blade Standard

cannour & section

dud i, 2D, t i.=30)

R-t0mm.4=t.5nnnr

,i=2OrpO ., B

-P.No.A AI A t) Blade Contour

-

VAU--P. 1322 03000 0.4000 Kaplan 4- P. 1308 04500 0.4000 Kaplan ---- P. 1323 06000 0.4000 Kaplan

/'

I I J I 03 04 05 06 07 0.8 09 10

t'

02 13 POch ratio at 0.78 0.3 0.4 05 06 07 08 09 10 .1 12 13.

Pitch ratio at O.7fl

Fig. 28. Blade contour

03 0.4 0.5 06

Fig. 29. Boss ratio series

02 0.3 04 05 0.6 0.7 0.8 0.9 1.0 I. 1.2 13 Pitch ratio at 0,78

Fig. 30. Area ratio series

to

ti

12 13 1.1 1.0 0.9 06 0.5 0.4 1.4 1.2 1.0 0.8 0.6 0.4 1.1 1.0 0.9 0.8 ç-) 0.7 ta 0.6 0.5 0.4 0.3

(10)

that of the controllable pitch impeller, and thus the

boss ratio of P. No. 1309 is chosen to be 0.30. The direction of rotation should be reversible at the fixed pitch side-thruster, and thus, blade

con-tour and blade section should be symmetrical about the center-line and the blade section has elliptic

di-stribution of thickness over a straight camber.

It

is of particular notice that the fixed pitch impeller has the greatest r;-value in the test in comparison

with other controllable pitch impeller shown in Figs. 28 & 30.

Effect of blade area ratio; Ae/Ad

The impellers P. No. 1322 and P. No. 1323 have identical particulars with those of P. No. 1308 except

for the blade area ratio, thus these three impellers

form the blade area ratio series. The blade area

ratio of P. No. 1308 is Ae/Ad=0.450, whereas those of

P. No. 1322. 1323 are AeIAd=0.300 and 0.600,

respecti-vely. The tests are conducted for differing pitch

ratio P0.7 within the range o.n=O.3O-l.2S. The

com-parisons of the obtained results are made in Figs. 30 & 31.

The results show the similar tendency to that of

ordinary propeller in the fact that the better effici-ency is experienced for the smaller blade area ratio within the range of impeller operation without

cavi-tation. There is almost no difference between the

results for Ae/Ad=0.300 and 0.450, whereas the clear

drop of the efficiency is observed for Ae/Ad=0.600.

Effect of the blade number; Z

Test is conducted in the standard duct unit for differing pitch ratio of three-bladed Kaplan type

impeller P. No. 1308-B. and the effect of the blade number is investigated in comparison with the

four-bladed impeller P. No. 1308.

The results are shown in Figs. 32 & 33. Effect of boss ratio; dID

The boss diameter of the fixed pitch impeller P.

No. 1309, is changed by covering the boss with the

paraffine and the impeller test is conducted in the standard duct unit for the differing boss ratios of

0.40. 0.45 and 0.60. The impeller blades are left the same and the blade area is differing in accordance

with the boss ratio. The test results are shown in

Fig. 29.

3.

Performance Tests of Hull Equipped

with Side-Thruster

3. 1 Testing method

A model side-thruster unit is installed on the ship models and the captive measurements of the attained lateral forces and the free-model test under operation

of the side-thruster, the rudder and the main propeller,

are conducted for differing conditions of the depth of

water and the pier walls.

The straight tow resistance tests of the model with the duct-openings on its submerged part are conducted

to investigate the increased resistance due to those openings.

Three models are tested; a super tanker (M. No. 1379), a high speed liner (M. No. 1463) and a cable layer (M. No.

1512), and they are wooden of the length L70=6m. The

body plans and the principal particulars of the these

three models are shown in Figs. 35-37.

As an actuator for lateral motion of ships. the more effective performance of the side-thruster can be attain-ed, the closer its longitudinal point of attachment is to the fore-end of the ship. However, the breadth of the

M, NO. 1379 Supe, tanker

4' 1000.15kg 3e 42709t

Fig. 36. Ship model (2)

hull at the point of attachment has the minimum limi-tation solely decided by the ducted-impeller system to be installed, and its position of attachment for the tested

models are decided in considerations of the data for

full-sized-units and the requirements of the size of the

model-unit.

Additional tests are conducted to investigate the

difference in the effect of the point of attachment of the units. using the high speed liner model. Additional test is also conducted for the super tanker model to investi-gate the difference of the straight tow resistance for the

duct openings cut out in the stern of the model. The position of these additional duct-openings are

given in Fig. 38. The model side-thruster unit has an

impeller of 90mm diameter and this unit is used to all

of the three ship models. The model impeller is made

similar to P. No. 1307. but the blades and boss are cast

solid with the pitch ratio of p.=O.75O, and the thrust

are controlled by changing the number of revolution of the impeller. Measurements are made at the model unit

for the number of revolution and the impeller thrust. These quantities, however, present sufficient basis to associate them with the quantitative relations among

thrust, torque and the duct axial force previously mea-sured in the series tests on ducts and impellers.

The performance tests of the hull equipped with

FP PP CCL 9 Model Sh,p L,.,' 6 r,, L,',. 19050m B inc.sk,n 81720mm ¡3 inc.sk,n 25946m

d ec.sk,n 33180mm 4 inc. sk,o I 0535m

L,.,. 6m L,.,. 105m ¡d,oc. sk,n 916.00mm Bmold 16m J,nc. sb,n 343 71mm ,!8,L 6m je I 207kg .3e 66501

\B F/(

L,

III

AP PP

M19o. 1463 High speed liner

Model SMp L,., 6 re L 150e, B inc.skin 857.20mm B inc.sk'n 21.428m 1 iec.skun 357.20mm, d ,mc.sk,n 8.930m .3,, 1146.29kg 4e 184041 AP 3

M No. 1512 Cable layer

(11)

AP

side-thruster are divided into three parts; the measure-ment of the side force exerted on the ship model under

captive condition, the measurement of the horizontal

motion of the free-running models, and the straight tow resistance tests of the ducted hulls. Under captive

con-ditions, the model is restrained by hard springs at the

two points in the center-line of the model at the height

of the center of the model thruster impeller, and the lateral forces exerted on these springs are measured.

Under free-running condition, the loci of ship motions are recorded by way of photographs taken from above. Simultaneous measurements are made on the number of impeller revolutions, thrust, the number of revolutions of the main propeller, together with the duration of the operation of the side-thruster or the rudder.

The tests are performed at the smaller towing tank

and the shallow basin at the Nagasaki Experimental Tank. The latter is specially prepared for the present

lo

I.J !

Ill/A I Ji

ri.

_IlL2fl

JL

Il®

w__ii

í;%

lui

i!i

1LL

I'i

______«o I

--.

A

A..

Fig. 38. Duct position on ship models

research program in order to change the depth of water easily and it has the dimensions of 15.9m length, 3.85m breadth and 0.6 m maximum depth of water.

3.2 Instrumentations for the tests

The model side-thruster unit used for the perfor-mance tests of hulls is shown in Figs. 39 & 40 and its

photographs are shown in Fig. 41.

Impeller is attached to the impeller shaft ® b way

of the thrust escapement spring ®.

Torque is transmitted to the impeller from the

im-peller shaft ® by way of the thrust escapement spring

®, and the thrust is measured by the thrust gauge spring ® by way of the thrust lever ®.

The number of revolutions (rps) are printed out dur-ing the tests through the revolution counter attached to

one end of the driving motor shaft. The control of the rudder position is made by the model steering gear

within the range of ± 35 degrees. M. No. 1379 Ship form (mt 1 (mm) lf/L (man) lb/d _Remarks (mm) Super tanker 6.000 331.8 0.050 0.500

1379 Super tanker 6.000 331.8 1a0.070 0.600 Stern duct

1463 High speed_liner 6.003 357.2 0.135 0.450 No. duct

1463 High sp.ed_liner 6.000 357.2 0.170 0.410 No. duet

1512 Cable layer 6.000 343.7 0.140 Ù.500 AA Section .=._ßl!!__i::_ t Thrust es ment spri Ii4uui

i

® ® Thrust Ie ® Thrust ga ® Mutar ah ® Impeller s

J!

60

i

I

.J',I

I1

IØu

ri')"

E 120

A

Fig. 39. Model side thruster unit Fig. 40. Model side thruster unit

cape -ng er uge aft haft

(12)

The maximum rudder position, however, are

previ-ously set at the suitable values for the tests, while the

remote controls are made to execute the rudder in either

side of port or starboard. Small lamps are attached at the fore and aft end of the model center-line and they

are made to blink once per each second. The motion of the ship model is recorded by taking photographs of the

blinking lights from above with a space-fixed camera

over the model basin.

3. 3 Considerations on the Test Results

3. 3. 1 Measurement of lateral force under

captive condition

The ship model is restrained at the two points in the

model center-line by the arms projecting out from the

shore and the reaction at these two points are measured to obtain the lateral force exerted on the ship model due to the working side-thruster.

The following notations are used in the

representa-tions of the test results.

Impeller thrust

Tkg)

Impeller revolution n(rps)

Resultant lateral force F (kg)

Point of application of

resultant lateral force x(m) fore of

Reactions at the

restraining points F1, F2(kg

Where resultant lateral force is the normal com-ponent of the total induced-force in reference to the center-line of the ship model. The positions of the

restraining points are different for the ship models and the testing conditions. In the notations, F1 always cor-responds to one of the two restraining forces closer to the fore-end of the model.

In the measurements of the restraining forces near wall, F1 and F2 are the components of the induced force normal to the wall.

Depth of water H (m)

(expressed in ratio to the draft of the ship model; Hid)

Clearance of the pier 1(m)

(the distance of the horizontal center of the

side-Fig. 41. Model side thruster unit

thruster on the ship model from the pier) Angle of intersection of the

model center-line to the pier O (degree

Displacement of the model

J kg

Breadth of the model B (m)

The non-dimensional representations, such as FIT,

Fx/T. L5, F2/J and T/J, are used in the analysis of the test results. The sign of T and n are assumed to be

positive no matter which sign the direction of rotation of the impeller has when confusions are not expected in the analysis. However, in the case of the force measure-ments near wall, the sign of T and n are defined positive

when the impeller causes the water flow out of the thruster duct towards the wall creating lateral thrust to clear the wall, and vice versa. The signs of F, F1

and F2 are defined positive when they are in the same

direction as that of + T. The depth of water and the

distance from the wall are defined to be infinite when the tests are conducted in the smaller towing tank.

(Breadth x Depth = 6.1 mx 3.65 m)

1) Bow thrusting in open water (smaller towing tank) The measurements of the lateral forces are made under stationary condition of the model for differing number of revolutions of side-thruster impeller.

The tested ship models arc as follows;

For example the measured values of T, F1 and F2 for M. No. 1379 are shown in Fig. 42 on the base of the impeller revolutions. It is apparent in the results

that T, F1 and F2 are approximately proportional to n2.

li

Tested models Impeller Rev. Test results

M.No. 1463

(High speed liner) 10, 15, 20,30 ros25, Fig. 44 M.No. 1512

(Cable layer) Fig. 41

M.No. 1379

(Super tanker) Fig. 42. 43

M. No. 1463

(Different position

(13)

12

n rps

Fig. 42. Bow thrusting in open water (v=O)

M.No. 1379)Super tanker)

Imp. thrust) 0.6 0.5 0.4 0.3

iuiila

10 15 20 25 30 35 n rps

Fig. 43. Bow thrusting in open water (v=O) The ratios FIT and F. x/T. L05 are shown in Figs. 43-45 for each ship models. For M. No. 1463 (liner), F/T and F. uIT. L55 appears to be increasing with the revolution n. In general, however, these ratios are considered to be independent of the number of revolution; n. For the rests of the test results, there-fore, the results in open water condition for n=25 rps is used as the standard of comparison.

(2) Bow thrusting near wall and bottom (shallow basin) The lateral forces normal to the wall are measured.

Assumptions are made that the lateral force due to the working side-thruster exerted on the ship

models acts in the normal direction to the ship

center-line, and the normal lateral force is obtained from the measured values of F1 and F2.

The tests are conducted for each of the three ship models for differing depth of water, clearance of the wall and the angle of incidence of the ship

center-line to the wall. Impeller revolutions are widely

covered only for the maximum depth of water,

whereas for the rest the tests are conducted for a

definite value of impeller revolutions.

The following combinations of the test conditions

0.5 0.4 0.3 L,., 0.2 1.0 0.5 10 15

M.No. 1512 (Cable (ayer)

M. No. 1463 (Nigh speed liner)

F FF

30

20 25

I rps

35 40

FT) _{np, thrust)}

o

are programmed for M. No. 1379 (Super tanker

model) and for example the obtained values of T, F1, F2 and n for H/d=l.8 and 0=10° are shown in Fig. 46. 10 15 20 M. No.1 37 (Supertanker

/

(:TT

/0.450m 4/ 1.500m rr' 1ii.. No 2 No. 1 r 0.135L 0.170 L

u..

iuuu

._

BOy .2\

7

°ónnct

9iii4

j

BO'5

ojjjj

Depth of water Angle of incidence to the wall Clearance of

the wall n Results

H/d fi(deg( I (rps) 0.537 B. ±10. B, lOB 20.30 1.8 10 s s Fig. 46 30 1.8-1.1 O 10 i, " 30 'i 25 30 30 35 10 15 20 25 1 rps 2.0 X 1 .0 o X -1.0 X 2.0 1 .0 0.5 0.5 0.2 1.0

(14)

0.5

1 .0

o

M. No.1379 (Super tankerl

v=0 z25rps

o r

S

-t No. 1379 Super -tanker)

Nd 1808

û 10'

For open water

o / 0.537B

1=5

/ = 1.55

30 20 10 0 10 20 30

rps

Fig. 46. Bow thrusting near wall and bottom (v0)

For open water

Fig. 47. Bow thrusting near wall and ..ottom.

From Fig. 46 it is apparent that in case the

side-thruster is working in the direction to push the bow towards the wall the impeller thrust T and the force F exerted on the model are almost the same as those

in the open water, being independent of the clearance

of the wall and the angle of incidence to the wall. Consideration, therefore, is made only for the case

where the impeller makes the water flow towards

the wall (T and n are positive) in the discussion of the effects of the wall and bottom. When n is posi-tive, the values F and F2 decrease with the distance

1

for the tested angles of incidence to the wall.

Whereas the value T has almost the same value as

that for the reverse revolution of the impeller, and it can be concluded that the impeller thrust is free

from the effect of the clearance of the wall. It can

be stated in general that T, F1 and F2 are approxi-mately proportional to n2. Therefore, it is possible to discuss the effect of the clearance of the wall with the values T, F1 and F2 for any value of the number of revolutions.

According to the test results, the impeller thrust

T is almost independent of H.

Therefore, it is possible to discuss the effectiveness

of the side-thruster with the impeller thrust as the standard of the forces. In this way, the resultant

0.5

Rd

Fig. 48. Bow thrustong near wall and bottom 1.0 1.1 12 1.3 14 15 1.6 0.5 1.0 0 17 18 1.1 12 13 14 15 16 17 1.8 H. d

Fig. 49. Bow thrusting near wall and bottom lateral force F and the resultant moment about the midship are expressed in ratio to the impeller thrust T as the standard; FIT and F. x/T.L00. and given in Figs. 47---49.

In this expression in general the resultant lateral force P and the moment decrease with the clearance of the wall, although the measured values are some-what in disorder.

Two examples of the test results of M. No. 1463

(High speed liner) and M. No. 1512 (Cable layer) are shown in Figs. 50 & 51 in order to make clear the

effect of the ship forms, and similar conclusions can be drawn as before. In these figures the values f01' open water tests are plotted for reference.

(3) Bow thrusting under small speed of advance (smaller towing tank)

The models are restrained with the lateral force transducers attached to the towing carriage and

propelled by the main propeller along the center-line of the towing tank. The side-thruster is then ope

rat-iII2:::-:::

o ¿-0.5373

--:

t - B / 1.513 17 18 11 12 13 14 15 H/d 16 2.0 .0 LO -2.0 3,0

(15)

14 0.5 1.0 0.5 o 0 _._ v=0 n 25rps

M. No. 1512 (Cable layer)

/ 0.53311

u--For open water

o o

-- -s--8 30

.---f

o.

-

₈ ₀

Fig. 50. Bow thrusting near wall and botton,

M.No. 1463 High speed liner)

O- 30 n 25tpo a

For open water

F

- F

o

Fig. 51. Bow thrusting near wall and botto?n

ed and the lateral force exerted on the model is measured. The tested speed of advance and the

impeller revolutions are listed below.

For example in Fig. 52 (M. No. 1379). the measured

values of T. F1 and F2 for differing revolutions nare

given on the basis of the speed of advance v/./gL.

Specific features of these results are that for a

con-stant n, the values of T is almost concon-stant. And

therefore, it is possible to discuss in general the

effect of side-thruster with T as the standard value.

to

Io

.0

001 002 002 004 000 006 0.07 008 009 01G oil 012 013

Fig. 52. Bow thrusting in open water (vO) The values F3 and F2 decrease with increasing ship

speed, but the rate of the decrease vary in accordance

with n and, therefore. it can not be concluded in general that the effect of the side-thruster is

dimi-nished in the speed range larger than a certain cri-tical point.

Under small speed of advance where the

wave-making resistance of the ship model is not large, it

is inferred that the conditions of the dynamical

similarity are reached when the speed of flow of

the out-flowing current from the side-thruster duct

and the ship speed change in proportional to each other. Thus. the measured values of the three ship

models are expressed in the non-dimensional forms on the speed unit niT/pA in Figs. 53-55. The results show that in the expression of v/.JT/pA and FIT. the resultant effect of side-thruster can be expressed by some definite type of function regardless of the ship form. And the effect of the lateral force in relation

to the impeller thrust is greatly diminished with

increasing ship speed and it may be concluded that the effect of the side-thruster is quite small for the

range of the ship speed v/.9ITJpA greater than a definite value.

In the present expression, the duct cross sectional area A is adopted as the standard of the scale. How-ever. in the present series of tests, the length of the

ship models and the duct diameter are assumed to

be constant, and thus, it cannot be decided from the

present test whether v/.//pA is suitable for the

standard of the critical ship speed or not. However.

the previous consideration suggests that it can be regarded to be suitable for the first approximation

of the phenomenon.

3. 3. 2 Initial turning and course changing tests

(1) Course changing tests for the liner form

The series tests on ducts and impellers are per-formed for the condition of 100 % slip of the impeller, and this condition corresponds to that of the

side-thruster working in a ship at rest. In order to

investigate the practical possibilities of the side-thruster, the effectiveness of the unit on the ship

under free running condition should be clarified. As an example high speed liner model is adopted to test the course changing ability by the use of the

side-thruster for the speed range from about i to lOkn. N 33179 i.( -

-0450,, r '

- . .

;:

i

T.._

_{-=4_.__L±}

---I...

I: Tested

model Speed ofadvance ImpellerRev. Results

M.No. 1879 0.7. M. No. 1463 M.No. 1512 ' n i, Fig. 52 o I - 0.53511 I=B I 1.511 or open water 11 12 13 1.4 1/il 15 16 17 1.1 12 13 14 15 16 17 18 !1/d

(16)

E-1.0 0.5 1.0 o e/Ì 'PA 1.0

M. No. 137g Super tanker)

Forward speed: n.- 0.1- 1.0 re, sec Impeller rev. : n -30 rps

Open water lOops +

O j

v/'IT/PA

Fig. 53. Bow thrusting in open water (vO)

M No, 1463 ) High seed liner) Forward speed: e. = 0.1- 1 .O50/sec Impeller rev : a = 30 rps

20rps c

l0rps +

v/IT/pA

Fig. 54. Bow thrusting in open water (vO)

M.No. 1512 Cable lager.

Forward speed: r, 0.1- I 0m sec

0.5 Impeller rev. : , = 30 rps .. Open water

20 rps...

n/i T/PA

Fig. 55. Bow thrusting in open water (vO) For five different values of impeller thrust for

each of the five different speed advance of the ship mode', the loci of the ship model are recorded. Each of Figs. 58--61 shows the results of the tests where

the impeller thrust are constant, and the ship

speed are changed in five different values. The ob-tained resuks are roughly summarized as folIow

Open water

M. No. I ¶40 lIlirb speod liner)

Fig. 56. »itlewayor-tllru.st 'measure7nent near

utah anti bottom

M. No. 1212 (Cable laynt

Fig. 57. Model side thruster unit installed in M. No. 1512

The effeCtiveness of the side-thruster is greatly diminished with the increase of the ship speed.

For the range of ship speed between about

1-3kn, the ship model turns with her stern swinging

out of the path of her center of gravity by the use of the side-thruster, whereas for larger speed than

this the path of the stern always lies within the con-cave side of the path of center of gravity.

)c) In turning by the use of the side-thruster. the after-end of the model traces the same or almost the

same path as that of the fore-end except for the spAed t-ange between l--3 kn.

In regard to (a). the theoretical study is made in

the Reference (4). and it leads to the results

consis-tent with those obtained from the tests. There is a

statement in Reference )fl. "Preliminary indications

are that the steering effect diminishes gradually with forward motion of the vessel until about 6=-7 kn

at which point a rapid decrease occurs."

Generally, the similar phenomenon to this can be

observed in the present series of tests, although there is minor inconsistency in the quantitative aspects. The effect of the side-thruster is mainly governed by the relative positions of the center of

lateral pressure acting on the ship hull and the

side-thruster unit, as stated in Reference (4). and thus,

the minor inconsistency in the present case may be

due to the difference in the ship forms. For larger

speed, the possibility arises, as is stated in Reference

(4), that the ship model turns in the opposite direction to that of the force applied by the side-thruster, in

accordance with the relative positions of the

longi-tudinal points of the center of lateral pressure on the model hull and that of the side-thruster.

How-o

(17)

16 r=O.1 r v=O.5 mzsec 2.0 Lpr 1.5 Lpr 1.0 Ln' 0.5 Lr o Side thruster started 2.0L V _{1.0 rn/sec} r=0.7 m sec l.5Lr 1 .0 Lep Direction uf 0 at every 2 sec O .5 Lee

M. No. 1463 (High speed liner)

Fig. 59. Side thrusting in open water ever, this phenomenon is not observed for the tested hull form, the range of the ship speed and the posi-tion of the side-thruster for the present case.

The fact (c) shows a specific feature of the side-thruster in contrast to the case of the turning by the

use of the ordinary rudder at the stern of the ship, where the fore and aft end points forms the paths of concentric circles. From this fact, it may be

in-ferred that in turning of the ship by the use of

side-thruster smaller drift angle, and therefore smaller increase of resistance due to oblique run-ning, are observed in comparison with the case of

5=0.5 rn/sec

\

\ 1

\'

e1\

i

1.5Lpp

/\ '\

.\

_\ OLpe r 0.3rn/se'c n= 25 rps v=0.l m,sec r l.Omsec Locus of FP& AP Locus of midship V=O,5rnsec r _{Olrn sec} Locus of FP & AP Locus of midship 2. 0 Lep V 1.0 rn/sec 0.7 rn/sec Direction of t at every 2 sec 0.5 L O Side thruster started, v= 1.0 rn/sec V=0.7 rn/sec 2.0 I OLpe Direction of t

¿it every 2 sec

O OLpp

311 2H IB 0 lB 2E

M. No. 1463 (High speed liner)

Fig. 61. Side thrusting in open water

the turning of similar intensity by the use of the ordinary rudder, and thus, the speed reduction in

turning may be smaller for the present case.

Fig. 62 shows an example of the record of the

turning under small speed.

(2) Initial turning tests for the tanker model

Observations are made on the

initial turning

transients of the super tanker model by the use of

the rudder only, side-thruster only and the combina-tion of the two devices, for a speed around 5-.6kn.

The state of turning is shown in Fig. 63. The test results are summarized as follows:

2B lB 0 lB 2B 311 2B lB

M. No. 1463 (High speed liner) M. No. 1463 (High speed liner)

Fig. 58. Side thrusting in open water Fig. 60. Side thrusting in open water

/

v=o.ii.om sec n - 1 8 rps O Side thruster started Locus of FP & AP - Locus of midship 3B 211 lB 0 lB 2E

(18)

M. No. 1463 (High speed liner) Fig. 62. Side thrusting in open water

n=O ,5::. 10' n= 10. 4=10' n=20, 4=10' n - 30,4=10' n 0, 5= n 10,6- 3 n=3O, 4= 0

Speed of approach - 05m sec Revolution of main propeIIer kept constant

M. No. 1379 Super tanker

2.0 Lm

1.5Lni.

1.0

0.5

O (Side thruster & helm start)

3B 211 lB O IB 211

Fig. 63. Turning in upen water

In the turning by the use of the rudder, the

model swings out the stern, whereas in the turning

by the use of the side-thruster the fore and aft end points of the model passes the same or almost the

sanie path each other.

Estimation of the capacity of side-thruster is

made on the basis of the observed performance, and

the ratio of the lateral thrust to the submerged

lateral area; (Lateral thrust)1L7,5. d=6=-'7kg/m2, as corrected into ship size, approximately corresponds

to the turning force exerted by the 10 degrees of the position of the ordinary rudder under speed of advance about 4=-6 kn.

3. 3. 3 Manoeuvring tests

One of the most important action of the side-thruster will be the manouevrability in the harbour or in narrow channels. Therefore, typical manouevres are performed

in the model basin in order to testify the merit of the device.

Scene of test is shown in Fig. 64.

(1) Tests for going alongside a pier

Three methods are adopted for going alongside

and two methods for clearing the pier to testify the

manoeuvres as the typical operation of ships near

the pier.

Figs. 65 and 66 show examples of the record.

M. No. 1463 (High speed liner) Fig. 6-t. An example of manoeuvre tests

M. No. 1075 (Supes' tanker)

Fig. 65. An example of manoeuvre tests Going alongside a pier (A)

The bow of a ship staying in parallel to the pier

at a distance of 2=-3 R front the pier is first turned towards the pier until the mooring headline can be

taken from the shore and then is made to stop by

the use of the side-thruster. (After this position, the parallel mooring is easily performed by the help of the main propeller and the rudder.)

For example the change of model positions at each

IO seconds are shown in Fig. 67 for M. No. 1379.

Going alongside a pier (B)

The ship is first made to draw near the pier with an angle of incidence of about 25 degrees to the pier

under small speed of 4'-=5kn. And then, the ship

turns towards off-shore by the help of the

side-thruster until she becomes parallel to the pier before she arrives at the pier and stops at the final position. An example of the transients is shown in Fig. 68.

Going alongside a pier (C)

The ship staying in parallel to the pier at a

dis-tance of 2=-3 B from the pier is first made to move obliquely forward towards the pier with the direc-tion of ship center-line kept unchanged by the use

of the main propeller, the rudder and the

side-17

(19)

18

thruster at the same time. And back with the

re-versing main propeller until the longitudinal travel during the first step is recovered and stop. Similar

M. No. 1912 (Cusblr layer)

Fig. (6. An example of manoeuvre te to

M. No. 1379 Super tanker

Rev,of thruster impeller: n 25rps Rev. of main propeller In O

Rudder angle t O

Fig. 67. Test for going alongside a pier (A)

M No 1379 Super tanker) Rev of thruster impeller :o ' 2 Stpo

Speed of approach :r 05m sec

Rudder angle Ie-. o

Fig. 68. Test for going alongside a pier (B)

M. No. 1379 Super tanker)

Rev, of thruster impeller: ns - 25rps Forward speed v= O-- O.5m.'oec

Rudder angle 0= 35p

Fig. 69. Test for going alongside a pier (C)

operations are repeated until the ship reaches the pier.

Figs. 69, 70 show the examples of the paths of the

manoeuvres.

Clearing a pier (A)

This is the reverse of the manoeuvre stated in (c),

and the ship lying alongside a pier leaves the pier

in oblique direction to the pier with the direction of

the center line of the ship unchanged. In this case also, the manoeuvre is performed for the Z-letter shape only.

Fig. 71 shows an example of the paths of the

ma-noeuvres.

Clearing a pier (B)

The manoeuvre for clearing the pier stated in (d(

is now divided into two steps. That is. the bow of the ship lying alongside a pier is first restrained

with the headline and the spring and then the stern

is made to swing out towards off-shore by the use of the main propeller and the rudder until the ship

center line makes an angle of 20-30 degrees to the

MIo. 1512 (Cable layen

Rev of thruster impeller: e - ± 25rps

Speed ot advance : r O-- O.5m./sec

Rudder angle :5:, 35P

Fig. 70. Test for going alongside a pier (C)

ti. No. 1379 Super tanker) Rev, of thruster impeller: - 25rps

Speed of advance : r= O 05m sec

Rudder angle :it 35

Fig. 71. Test for clearing a pier (A)

M. No. 1379 (Saper tanker)

Rev. vi thruster impel)er etas - ± 25rps Rev, of mu)n propefler tne O

Rudder angle 5=35' P

Spring

\\\\\

Fig. 72. Test for clearing a pier (B)

(20)

M. No, 1379 Super tanker

Channel width : I, 21f Speed of advance: r 05m sec Angle of turn :0.- 20 Rev, of repeller :n - . 25rps

r0

Fig. 73. Manoeuvre in narrow channel

M, No. 1379 Super tanker)

Channel width :h 2B Speed of advance v= 0.5 rn/sec

Angle of turn : 0= 30' Rev, of impeller : - ± 25 rps

Rudder angle : ô=20'P

Fig. 74. Manoeuvre in narrow channel

piel. And then, the headline and the spring are

untied and the bow is pushed towards off-shore by the side-thruster until the ship center-line becomes in parallel to the pier.

This conditions is shown iii Fig. 72.

The results of the tests are summarized as follows.

i )

For th ship at rest the turning is quite

easily performed. In the turning of the ship

model from the state of stationary condition

by the only use of the side-thruster the center of turn lies at the point 1/3--1/2 L00 from A. P.

for the three ship models, and therefore, it is

quite easy to perform 360 degrees turn within

the circle of the diameter of l.2-1.5

ship-length.

It is possible to go alongside a pier by the use of the side-thruster for the ship drawing

near the pier with an angle of incidence.

The ship staying in parallel to the pier or

the ship under small speed of advance can be brought to the alongside condition by the sui-table use of the rudder, the main propeller and the side-thruster within the longitudinal space

of water of about 2 ship-lengths. Clearing manoeuvre by the reverse manner to this can be easily performed.

By using the headline the ship can be

brought from the alongside condition to the

state of cleared position in parallel to the

pier at a distance of l.5-2.0 B from the pier within, the longitudinal space of water of at

least 1.5 ship-lengths.

(y) The .high speed liner form, which is fine, yields more effective operations and shows more .rapid response to the executes of the

side-thruster than the full super tanker form. (vi) Under calm condition, the capacity of the

side-thruster is quite sufficient for the ratio; (Lateral thrust)/L00. d= 12 kg/m2. as converted

into thé ship'.size, to perform above-mentioned ship operations. For lower capacity than this.

-

i,,. ,4

-:'__

M. No. t37ll Supper tanker> Fig. 75. Manoeuvre in narrow channel

the turning motions are somewhat delayed,

although it may be serviceable to the ordinary ship operations.

(2) Manoeuvres in narrow channels

As an example of narrow channel manoeuvres, tri-als are made to pass a super tanker model through a narrow bent channel of the breadth 2B and 3B and

the angles of channel intersection 150 and 160 degrees, by the use of the side-thruster, and the path of the

model are recorded.

Test results are shown in Figs. 73-=75.

As the results, the following facts are clarified. In the case of the breadth of 3B, the model can be safely manoeuvred to pass through the channel

of the both cases of angle of intersection at the

bent corner 150 and 160 degrees under 5-=6 kn speed of advance, by the use of either of the rudder or

the side-thruster.

In the case of the breadth of 2B. however, it is difficult to pass with the use of either of the rudder or the side-thruster, while it is much easier to pass

with the combined use of the rudder and the

side-thruster for the both cases of the channel intersec-tions under 56 kn speed of advance.

c The capacity of the side-thruster is quite

suffi-cient for the ratio; (Lateral thrustVL00. d= 12-13

kg/rn°. as converted into ship size, to pass the

above-mentioned narrow channels. For lower capacity

than this, the manoeuvring motions are somewhat

delayed, although the manoeuvre will be performed all the same in sufficient safety when the speed of advance is fairly small.

(The position of the side-thruster on the tested model is 0.05 L00 aft of F. P.)

(21)

r

3. 3.4 Resistance tests of ducted hulls

To answer the question raised concerning the in-creased hull resistance due to the side-thruster duct, straight tow resistance tests are conducted for three

different ship forms.

The conditions of the duct openings are listed below. Model No. M. No. 1379 M.No. 1463 M.No. 1112 A-1 20 A -.-B-B Section Bow

Bow and stern Bow (Fore ones only) Bow (Aft ones only) Bow (Larger roundness

at the corner) Bow (Conical £airings(

Bow Duct openings

" "

II.'

B- B Section

T'

ETT Figure Fig. 38

The results of the resistance tests are shown in Figs.

77-79. According to the test results, the increased re-sistance due to the duct openings is negligible at the

liner forni (M. No. 1463> regardless of the shape of the duct opening, within the possible range of the type.

For the cable layer form )M. No. 1512) increased hull

resistance is quite small, and the increment of the

residual resistance co-efficient is about 4 % for the total range of the speed of advance.

For the super tanker form (M. No. 1379), the effect of the duct openings is comparatively large and the test results for the bow openings and that for the stern ones

show that the increment of the resistance is 10% for

lower speed and 5 % for higher speed of advance in the scale of residual resistance co-efficient.

It may be concluded. therefore, that the effect of the

duct openings on the hull resistance is small for fine

ships, whereas for full ships considerable amount of in-creased resistance is observed.

A- A Section

Fig. 76. Tested shape of hull opening

0015

0.0 10

0.10 0.11 0.12 9.13 0.14 0.15 0. 6 0,17 0.18 0.19 0.20 0.21

r /&LWL

Fig. 77. Residual resistance coefficients

MHo. 1463 (High speed liner)

Full toad even keel

60'4Load 1°,Trim A

T

/

Ap" -f'p 80.200cl- -'I No. I Duct .15016 0)70.08 5,19 0.20 0.21 0220.230.24 0,25 0,26 027 0280290,300.31 0,32 0.33

Fig. 78. Residual resistance coefficoents

M No.1379(Super tanker

f;

Foes duct.

Marks Toot No. Date of capt.Temp. 4 g dnocr LoeL m

A O T00 943 Feb 27. 0963 11.3

B S T00942 Feb 26. 1963 11.4 1300.05 332.80 6.008

C ® T0 046 Feb 28, 1983 11.3

Marks 5

WI. WI. c Bld p /V 06o s Remarks Duet

A O

0.7843 0.7923 0.9905 2.463 6.3635 Full toad

Naked

B S Fore

C B Fore &

Marks Tmt No. Date of expt.Ts.mp. _kg dauer

_{tc m}

A O T08938 Feb 23, 1960 21.3 B S 935 22 11.2 C 6 940 25 11.3 1146.29 357.2 6.167 D 944 27 11.3 E Q 941 26 10.4 F 0 936 22 11.2 698.14 230.3 9.774 G 945 28 11.3

M.No. Duct S)upe R

M.1463 Bow No.1)Sharp 0.01!) M.1463 90w No.l(ROUfld) 0.10!) M.1463 82w Plo. 1(Fairing) 0.10!) M.1463 80w No.2(Sharp) 0.01!) M.1379 Bow Sharp) 0.01)) M.1379 Otero (Sharp) 0.01!) M 2512 Ros (Sharp 0.01))

Marks C,, Bld _Sw/Va Remarks Duet

A O 0.6066 0.6200 0.9700 2.400 6.318 Full Naked S No.1 C 6 No.2 D No.1 E Q (covkwl) FO 6.6029 0.6280 0.6285 3.722

6.810 1r°t

No.1 G

Nl

kit

M.1379 4, No_2 No,) M.1463

4j/

4_J l.M.0512

I'

AP EF 0)5 'f 020- u. 0.00 0019 lo 000 .010 0005-Fig. 76 Fig. 38

(22)

Fig. 79. Residual resistance coefficients Thus, the resistance seems to increase in accordance with the amount of the projected area of the duct open-ings as they occupy in the body-plan of the ship. 4.

Simplified Evaluations of the Performance

4. 1 Equations of motions

Referring to the moving system of co-ordinates as illustrated in Fig. 80 the horizontal motion of a ship can be described by the following equations of motion under some simplifying assumptions:

MriiMyrr=XX(ß,r,ô)

Myi'+M.ratr=EY(ß,r.Th (3)

I*=XZ (J3,r,ô) J

where the notations are all referred to the list ta the

end of this report.

An extra terni is now introduced in each one of the equations in Eq. (3) in order to make them describe the effect due to the application of the lateral thrust of the side-thruster, and the following equations are obtained in the form of non-dimensional expressions.

_M11'.g'_Y2'.S'+(M'__ Y' r'= - Ys'Ö'+Th

- Z2t. ß'+l' r' +Z,.' r'= Z4'.ö' + T5'. l,' (4)

where the prime denotes non-dimensional quantities.

and they are defined as follows:

L95d

= Y2

L. dW

=z4, dU2 Yr'=Y1J Lpp2dU Zr'=Z1./- L55dU

ß'= 9

t=Lppr/U=Lpp4/U

i"=L5i'JU

Ö"zzÒ, I5'reax!=5o'

T5t= Ts/ L5dU2, ¡Ty'mat = za'

= l5/L5, t' = Ut/L05

The first equation of Eq. (3) is neglected because it is less important for the present purpose.

In order to find the solution of Eq. (4) for the

sim-plest case, it is assumed that some definite amount of the lateral thrust is applied suddenly at the time t'=O,

and kept constant ever afterwards. The solution takes the following form:

i t. t, 1+ 1 1 \{Ae T1' - B'e T2' T2' - T1') (5) where F (r',', ö,')= (Y4'15'Z4')+ô,' (Y2'Z4'+Z4''Y4'fl 1l1'9' _{[_}

,f 1

i - F'(r01. ô01) L'° - 1W' + ôo"Zo' (i,,

-

_T3')]

_(2')

M0' _r

7f 1

1 - F'(r0', ô0') [:0 T2, - .1W' - i 1 1 \ i i ¡,T2' - T3')J X)-j--T9'

= 2iVIy'j::' [(My'Zr'+i:z' Y2')

T2'

J(My,Z,t+IJYß')24M9l.I1.A

_J

Y2Z5

_{A=Y2'Zr'Z2 ([Wx'Yr')}

1 Y,0'.Z2'+Y2'.Z8'

T3' ]14'u' Zt'

An approximate solution can be obtained by the use of the method after Prof. Nomoto. as it is proposed for the general problems of the horizontal ship motions, and

it is. for the same initial condition:

r'(t')= ('. 50')11_ {F(ro',

o) e'''

+ F (o, O')

e'4i}]

(6)

where

T' T' T'

_-

M91.15' 1 2 '

T"(T'+T'

_-

i M11'.Z4' 1 2 i Y4'Z4'+ Y4'Z4'

However, the above expressions are not valid when the advance speed of the ship is zero ox' fairly close to it, and the following equations, for instance, should be used in stead of Eq. (4).

Y2 S - M5. ¿g,. r + Yr r + T5 = 0

(7)

Z2 S - I-- )'Zr .3' + T, ¿5=0

where l, is the distance between the center of gravity

and the pivoting point of the ship in turning motion at

r'(t')=-F(:', ô0')

o

Yo

Fig. 80. Axes of coordinates

Mrko Teot No. Date of expt. Temp.

C 4 6 dprrmm LW.,. m A O TRS 937 Feb 23, 1563 11.3

1297.0 343.71 6.238

B S 939 25 11.3

Marku C,, B/d _{50/V,"5 Remarko} Duct

A O 0.6138 0.6318 0.9715 2.665 6.465 U b'' Without duct B S With duct la-1, 00! 5

M. No, 1512 Cable layer)

5 0.010 z

¿ L'

0005