Current research work of the Swedish state shipbuilding experimental tank

Lab.

v.

Scheepsbouwkunde

ARCHIEE

CURRENT RESEARCH WORK OF THE SWEDiSH STATE SHIPBUILDING EXPERIMENTAL TANK .

by

Hans Lindgren

Technische Hogeschool

Delft

STATENS SKEPPSPROVNINGSANSTALT

(THE SWEDISH STATE SHIPBUILDING EXPERIMENTAL TANK)

Nir 8

GOTEBORG 24

₁₉₆₄

ALLMAN RAPPORT

FRAN

Current Research Work of the Swedish State Shipbuilding Experimental Tank

by Hans Lindgren

Summary .

'A review of the research organization at the Swedish State

Shipbuilding Experimental Tank is given in the paper'. Current _work

is discussed and research results are given regarding resistance, propulsion, cavitation, seakeeping, manoeuvrability and ship trial and service analysis.

STATENS SKEPPSPROVNINGSANSTALT

Goteborg 24, Sweden

1. Orsremization

The Swedish. State Shipbuilding Experimental Tank (Statens Skepps-provningsanstalt, SSPA) in Gothenburg, is a state institution under the jurisdiction of the Ministry of Commerce.

Under the supervision of the Director (Dr. Hans Edstrand), the organization consists of three technical departments,

.Vis:-Experiment, equipment, instrumentation and workshop; development and, maintenance (Head R. Rodstrdm)

Routine work, drawing office; design and calculation (Head

I.

Williams)

Hydrodynamic research, development (head H. Lindgren).

In the present paper, mainly the current activities of the research

departMent

will

be discussed. The department is divided into the following

sectiohs and groups (April

1964):-2. Research Activities and .Financincl

The research work at SSPA is sponsored by:

The Swedish Navy (Royal Swedish Naval Administration) Civil Customers (Primarily Ship Yards and Ship Owners)

Grants and Foundations connected to the Tank Own research work (sponsored by the State).

Unfortunately

only

a minor'part.Of the research results obtained ate being published generally.. Most of the results are given in con-fidential reports to the Navy., to civil customers and as unpublished

internal retorts. The research work sponsored by different grants and

foundations is normally .reported either in the series Of "Publications

of the Swedish State Shipbuilding Experimental Tank" (Meddelanden fr6.n SSPA)

or as

a

"General Report" (Allm'e'm rapport).

About

two thirds of the total capacity of the establishment is devoted

to research' work, the rest dealing

with

normal work. A rough survey of the

research work with some examples, methods and results follows.

Section or Group Principal ScientifiC Officers

Propulsion, cavitation Seakeeping, manoeuvrability Navy research

Fundamental hydrodynamic and hydroacoustics

Ship trial and service analysis

C.-A. Johnston, J. Kilborn N.H. Nortbin

B. Huss G. Dyne

B. WadmaLk

3. Propulsion

:Basic propeller theory

The demands, for a stringent propeller theory have increased primarily' due to increased interest

in:-Conventional propellers with special requirements;

e.g.

noiseless propellers, propellers suitable for

_{monhoMogeneoUs}

flow conditions

Non,-conventional propellers;

e.g. ducted

propellers, contra-rotating

PropellersQptimumproblems connected to propeller

efficiency and

_cavitation

'properties.

The requirement for stringent propeller theories. has also increased

with

the

development of fast digital computers.

At

SSPA considerable work has been devoted to the development and

checking of new theories, and computer programmes for use then carrying out propeller calculations, and new work is now in. progress. A schematic diagram for propeller calculations may look like Fig. 1. The most

com-plicated

problems

in the programme are concentrated in the blocks 1

(induced velocities) and 11 (lifting, surface effects).

\

It has been shown (1-2)1 that the

use

off-values for finite number

of blades according to Goldstein is questionable for propellers with

non-optimum circulation distribution. Fig. 2 illustrates the differences obtained for a case investigated. A computer programme based On the induction factor approach, as briefly described in (2) has therefore been .developed at SSPA

and is now in eUrrentuse (block 1).

The Gin2e1 and Ludwieg pioneer work has been the starting _point for

manynowinvestir!'ations

regarding the lifting surface problems (block 11).

JohnssOn has critically analysed and

applied a. number of new theories

_and

shown that great differences exist, see Fig,

3.

It was decided that a

computer programme should be developed based

on his work and dn

the main

following the principles proposed by Piens The programme is now ready and

will he aPplied

for different types of propellers and it is hoped that it

will throw further light on the influence of different parameters _{on the}

streamline curvature induced by propeller blades.

1)

See:IReferences

in

Section 10

STATENS SKEPPSPROVNINGSANSTALT Goteborg 24, Swede

FinallY,

a complete general nrogramme, in princible similar to the block

Scheme; Of Fig.

1, is now beihg

worked out. The programme will be made

flexible to allow different alternatives to be calculated., for instance with regard to blade section. shape, circulation distribution and strength cal-culation.

Propellers in irregular flow'

A basic study of the influence of wake distribution on the momentary

load distributions of a propeller blade is proceeding. It has been found

convenient to Use a quasi-stationary approach to the problem. Using a special computer programme, based on the fundamental propeller and profile theories, it is poSsible to calcUlate, for example, the radial circulatie,, distribution. and the induced flow curvature and thus the pressure distribution

along a profile. Fig. ₄ indicates that the momentary distribution differs

appreciably from the distributions in homogeneous flow.. The work was primarily undertaken to provide. a basis for further studies regarding instatiOnary

forces on a propeller and the development of cavitation in an irregular flow' distribution. Systematic experimental studies of propeller cavitation in wake distributions will be treated below.

Ducted Propellers

A method suitable

for

the design of ducted propellers and pump jets

has

been developed at SSPA (3), With the method, it is possible to

_take

account of the mutual interference between the propeller and the nozzle. The influence of the circulation distribution of the, propeller blades and the nozzle, the thickness distribution of the nozzle and the three components of the induced velocities can also be dealt with.. Tha basic assumption's and procedure are summarized

below:-Starting from the assumption that the number of

blades

is infinite, the propeller is represented by a continuous distribution of vortices. These Vortices consist of ring-vortices, so distributed that the induced radial and axial moan velocities correspond to those induced by the real. vortex system of the propeller, when a lifting line approach is used.

:Furthermore, rectilinear vortices which induce the corresponding tangential

velocities are introduced. For the same purpose, the

skeleton

_{line of the}

nozzle is represented by

a

number of ring vortices and the thickness

dis-tribution by a number of

ring

shaped sources and sinks. When the Velocity

field induced by the nozzle in the propeller field

has been determined,

_the

strength of the vortex systems

of

_{the propeller is adapted to give the total}

vortex and source-sink. systemt of the propeller and the noz2le at the

nozzle boundary are determined by an integration. Thus the shape-of _the

nozzle can be calculated.

:Because of the infinite number of blades assumption, a direct'

calculation of the pitch .of the propeller gives Pitch values which _are

too low. Therefore, a conventional propeller design. method must be _applied.

The calculations are based on the calculated velocity distribution _{and on}

the value of. the propeller thrust, which differs from the _{total thrust}

and which can be obtained as described above. The calculations _follow

the method described under "aasiocpropeller

theory".

_{To check the basic}

assumptions, the two methods have been compared. Calculations

_were

_Carried

out

for

_{a non-optimum propeller (without nozzle) with the thrust coefficient}

K, =

0.23 and the advance ratio J

0.95.

In the enclosed diagram, Fig.5, the induced tangential and axial velocity components are compared. The curves' represent results obtained using:,

the new method assuming the number .of blades z

the new

method

corrected to

z = 5 by use

of the Goldstein

,

'-values (strictl

valid only for

optimum propellers)

the induction factor method,

z = 5

the induction factor method, z =. 20. (20tx).

The diagrams show very good agreement

between the curves obtained according

to a) and d) for x > 0.5. The Maximum difference in pitch

_{is less than -3%.}

Contra-rotating propellers

In

accordance with,

the principles

_{developed by ierbs and Morgan,}

a computer programme has been

_{developed at SSPA in}

_{cooperation with}

F'acit Electronics AB to be

used for the calculation of

_{contra-rotating}

Propeller systems.

Starting from propeller thrust, diameter

of the forward

_propeller,

number of blades, distance between the propellers, wake

distribution and circulation

distribution,

_{the pitch distribution for}

an ecuivalent single propeller is first calculated. This procedure

reauires trial and error calculations _{to Obtain the correct thrust and}

circulation distribution. Thereafter, the influence of _{the interference}

betwee:7 the propellers on the pitch and circulation distribution and the relation between the propeller diametersis determined. Thereby

toroueHbalance is presumed. From these calculations the,

radial distribution

of cireulation,

thrust, torcue and local cavitation numbers

are Obtained

STATENSSICEPPSPROVNINGSANSTALT 5

'Goteborg 24, Sweden.

;Finally,

normal propeller calculations. similar to the single screw calculations mentioned above, have to be carried out for both the Propellers

for

the

detail determination of pitch distribution and profile shape.

Thereby: the influence of viscosity and induced flow curvature

is

intrOduced.

The characteristics of a pair of propellers designed mainly according to the principles outlined above are given in Fig. 6. The main design data there:

z=4

AD/AD _44%

J

1.78 2EK /2 = 0.168

At a

0.75

bubble cavitation starts around

0.75

R, Fig. 7. In

the present case, the desigr thrust was obtained with an error of about _4%,

whilst the difference in torque between the forward and aft propellers

amounted

to

about 6r/Q at the design J. The final method for lifting surface

calculations was not applied when calculating these propellers. It is hoped that the introduction of this method will improve the results.

4. Cavitation

Propeller cavitation in wake. )ealcs.

The problems connected with propeller cavitation in.irregular flow distributions are very complicated and many difficulties remain to be

solved.

As part- of the cavitation research programme in progress at SSPA, tests have been carried out in the cavitation tunnel to give some informa-tion Of the influence of wake peaks of varying shape and amplitude on the inception of propeller cavitation as well as on the extension of cavitation at different propeller loadings.

Starting

from

homogeneous flow, wake peaks have been generated by a

long,

longitudinal plate, mounted in the cavitation tunnel. ProtelIers, have been tested in different pOsitions abaft the trailing edge of the plate.

In

order

to increase the wake peak, nets of different dimensions have been

mounted

on the sides of the plate. The test results have been compared with Similar results obtained in a wake field generated by a dummy after-body model.

;A complete test report is in preparation. Figs. 6-10 illustrate some

of the

resUlts.

Obtained. On the top of the Figs. the relative Velocity

dis-tributions at 0.9 R in the different; wakes are. given. The local velocities

I

Fig. 8. The nominal mean velocity

Fig. 9 The velocity

in

the 900 position (undisturbed flow)

'Fig. 10 The veIOcity in the 00 position (top position)

The corresponding cavitation patterns obtained

on

a propeller

blade in the t.013 position are illustrated in Figs. 8,- 10 with sketches

and photographs. The a and J values have been based

on

the three

alter-native reference velocities mentioned above

and

correspond to the dummy

model case, it is assumed

that

the effective velocity distribution is

similar to the nominal distribution.

All the sketches indicate the great influence of the wake peaks.

Only Fig. 8 corresponds to the same

loading

for all the cases, whilst according.

to the case in Fig.

9,

homogeneous flow corresponds to the lowest thrust

loading and

according to Fig. 10, homogeneous floW corresponds to the highest

thrust loading.

The ieSults shown. in Fig, 10 are especially interesting

and indicate

that the nominal, narrow wake

peak

obtained abaft the plate is not effective,

The homogeneous flow case in mainly similar to the dummy model case, but good

agreement is never abtained.

Full scale propeller cavitation studies

The stUdies of full scale

propeller cavitation

include:-Photographing ship propellers in operation Propeller erosion studies

Acoustic

studies of cavitation

inception.

In Sweden a special flash-light has been developed on behalf

of

SSPA. Its capacity is sufficient for taking full scale photographs of

propeller cavitation On large single-screw merchant ships. It has been

used, in cooperation with Swedish 'shipyards, for studying

the

cavitation

Patterns on a nuMer of large tanker tropellers. The purpose of the tests

and the arrangement have been briefly., described by

Edstrand.(5).

Fig. 11

show a comparison of ship and model caVitation photographs, with a

pro-peller blade tip in the position 30 and 40° tort. A well developed tip

vortex is clearly .visible.

An extensive programme is in progress for studying erosion patterns

on fUll-scale

propellers and Comparing them with cavitation Pictures from

model tests. Some eXample t from this work is given in (6) were also the

. I

STATENS SKEPPSPROVNINGSANSTALT 4;iiteborg 24, Sweden

paper and illustrates a base of back cavitation on the model propeller and the corresponding erosion patterns on the ship propeller.

The acoustic studies of propeller cavitation inception in ship

and Model scale have given interesting results and indicate., _{among other}

'thing, that full scale cavitation noise starts at higher. pressure than expected from model tests and theoretical calculations. The influence

of gas content,

nuclei and free bubbles seems

_{to 'beIdecidive.}

FundaMental. cavitation studies

I Different and more or less fundamental

studies

of cavitation and

cavitation inception are going on

at SSPA. Here may be mentioned

_an

.extensive study of Cavitation On rotationally symmetric head _{forms, of}

different shape (7), a survey of information, available in the literature

around the origin of cavitation (8) and studies concerning _{gas bubble}

resorbtion in cavitation tunnels (9).

5. Seakeeping

General seakeeping studies

The work on seakeeping at SSPA'

covers:-Theoretical studies

_and

investigations

Model testing

Ship. service

analysis.

The first item includes fundamental studies with regard to test

methods and scale effects, analysis methods and ship _{prediction procedures}

(10).

_The

_{second two items will be further treated below and in Section 8.}

Model seakee ino testing

The model testing programme'

includes

_commercial

tests

_{with actual}

ship projects, systematic studies of the influence of different form parameters and other special tests.

In (11) a description of the test facilities, _{instrumentation and}

test procedure at SSPA'is given. Some results _{illustrating the influence}

of fore body sections on motions and propulsion in _{full load and}

_ballast

conditions are summarized in (11) and (12). The _{load draught tests include}

cargo Ships with

6

0.675

and tankers with

_dr

= 0.794;

_{Only the first}

Pp

Pp

mentioned ships are tested at ballast draught.

Pig.

13 from (11) indicates that in _{waves longer than the ship,} 7-shaped fore body sections _{are preferable rnom the}

of viest. In shorter

WaVes.

the U-shaped and'bulbows bow versions appear

to be advantageous. The general trend. found by Bengtsson in these studies

was that with regard to. Motions V-shaped fore bodies were advantageous in

waves equal to or longer than the model. For shorter waves the U-shaped fore

bOdieS seem to give the best results. With regard to resistance, U-shaped

fore bodies are in all cases.superior in still water and in

waves shorter

than the models. At load draught condition the V-shaped models appeared to be

superior in long waves', whilst in the ballast draught tests no clear trend

could-be detected.

:A. study concerning the possibilities

of

calculating speed 10as in

waves,from resistance tests is illustrated in Fig. 14. The speeds in

'different waves obtained from self propulsion tests, keeping constant

torque and rate of revs. respectivily, have been compared with the

.corre8pending speeds calculated from, resistance experiments. Methods

proposed by Abkowitz and Bengtsson have .been applied.

The model results:may be used to compare ship forms, of any length.

In order to extend the presentation to motions in irregular seas, still

aPpliCable to

all ship lengths, Bengtsson introduced a simple energy

spectrum in the form of a bandlimited white noise. The reader is referred to the original publication for further details.

An interesting comparison Of the behaviour of high speed craft

of different design has been carried out and

is reported in (13). In

Fig. 15 the increase of Model resistance

in

waves of different length but

constant height are given.for a shorter hard chine and a longer round

bilge type boat. In still water the two boats are similar, but with

increasing wave length the longer round bilge boat is superior. Special tests

Special tests of varying type may be carried out. in -waves. An

example is illustrated with a photograph, Fig. 16, taken from (15).

Complete mooring tests of a salvage ship in different waves and different

angles to the waves were carried out and model motions and forces in the

mooring cables were measured. Models of different shame were compared.

6. Manoeuvrability

.Problems

connected to ship

steering

and

manoeuvrability have been

the'

objects of intense investigations at SSPA for some years. The work covers' merchant ships as well as naval surface ships and under-water bodies

21 it the reference area. (M;(4 0 is the condition for "static"stability.)

STATENS SKEPPSPROVNINGSANSTALT ₉

Goteborg 24, Sweden

and has resulted in a great number of reports, publications and articles. The investigations

include:-Basic theoretical studies

Model tests with radio-controlled and captive models Sip trial analysis.

Basic investigations

A review of the problems and progress primarily connected to the steering and control of surface ships is given by Norrbin (15) together

with

an

introduction- to the modern treatment of the characteristics and

' stability of ship motion. The general equations for the motions of a ship are formulated and the stationary and non-stationary forces on hull and

rudder are treated. Finally the common criteria

for

the dynamic stability

on straight course and the directional stability with an automatic contrdlare

derived by rigorous methods.

The general criterion for dynamic stability with fixed controls may be written as an inequality of two distances,

Nr

_>

Yr-m Y

where

NR and YR indicate moment and force dirivatives in

pure rotation Whereas

N and Y Iindicate moment and force derivatives in

oblique towingl.all in non-dimensional form and referred to the

centre of buoyancy; in is the Mast.

This. means that the resulting lateral force in pure rotation must be located in front of the centre of pressure in oblique towing.

Dyne (16) has made a systematic study of the forces on a certain

class of underwater bodies and developed a simplified theory for estimating

all first-order total force and moment derivatives. He has, among other

things, found that as a thumb-rule for preliminary investigations the criterion above reduces to

M'<

0.33

°C

. The frequency response analysis has been applied by Norrbin (17)

to evaluate the rudder transfer functions from torpedo and submarine full scale tests, and he found that a graphical analysis in the log-decibel diagram is usually superior to the more elaborate digital techniques.

! The use

of

a similar method for the studies of surface ship zig zag

test results has also been discussed by Norrbin (18). The effects of "large-value" nonlinearities in the hydrodynamic constants are found to

-be quite Small even in the 200 manoeuvre, also the response to the

higher harmonics of the rudder motion. An extended series of zig zag tests. a.-L different frequencies is recommended to allow an. evalution of the full

transfer function from helm angle to change of heading. The standard

zig Zag test, however, is suitable for finding the two constants K'and

of the first-order steering equation,

as

first suggested by Nomoto in Japan.

In its non-dimensional form this equation is '-y.

+ 7//

=

The definitions are understood from Fig. 17. The two upper diagrams

illustrate the analogy between the building

_up

rate .of change of heading

(IP)

of a ship and the potential V across :a capacitor, which is being

charged from a constant, selectable voltage supply. The K'is a measure of

the turning ability of the ship, the time lag

Viz

a measure of its inertial sluggishness. It is shown in ref. (18) that neither of these characteristics are evident from a mere knowledge of the number of ship lengths in the

period of the standard manoeuvre.

Nortbin.has given a simple method for a.rapid determination of K'

and T'from the zig zag test. By the aid of the help diagram, Fig. 19, T'

can be obtained as function of the frequencyt4' ( _{2111/period in ship}

lengths sailed) and the phase lag of heading behind rudder angle,

_{f. The}

spot representing (WR), Where R the amplitude ratio of course angle/

/rudder angle, is plotted in Fig. 19. A transparency of Fig. 18 is placed on

Fig..,19 so that the

(WR) -

spot corresponds to the correct T'-value in

Fig. ;18. The correct K'-value may than be obtained by reading off the scale

of K'against the 0 db

line.

Tests with free running mOdels

' At the 9th ITTC in Paris 1960, a contribution by Norrbin was

pre-sented (19), including a short describtion of the methods and equipment used at SSPA for tracking models in steering tests. The position and orietation of the model at each instant are defined by two angles and by the heading deviations _{from a suitable target}

at Moderate helm angles. The discrepancies are primarily due to differences

in Machinery characteristics,

STATENS SKEPPSPROVNINGSANSTALT 11

Goteborg 24, Sweden

recorded. The plotting procedure is illUstrated in Fig. 20, showing a

spetial plotting board with pivoted rulers.

or

triangulation On Which

the original paper records are placed.

A series

of

turning tests with ajibre glass model of a 9000 tons

d.w, cargo liner has been reported in (20). The tests were carried out

in a monoeuvring lake and the manoeuvring equipment

and

instrumentation

Wascontrolled by radio. The tests were carried out to give information

on:

The validity of linear, theory

The influence of hull, draught, trim. and.'heei The influence of bilge keels

The Merits of different types of rudder

The correlation of model. test results With full-scale trials. The presentation method used to obtain the steering index. ICis illustrated. in Fig. 17. The.determination Of effective time lag T'from turning circle tests is often made difficult due to initial disturbances, and it is necessary to extend the first-order-theory to handle a more general case as described in the publication. An alternative: Method makes use of "advance" measurements of a series of turning tests at different

helm angles, 17) and it is recommended for finding the important

value of the time lag in normal steering manoeuvres.

Further results of interest are illustrated in Pigs. 21 and 22.

Fig. 21 indicates a clear sternward trend of the pivoting point P.with

higher turning rates.. For "normal tight" 'manoeuvres, P is closely aft of the bow. The effect of bilge keels is small in this Case. In general the free turning tests with merchant ship forms have shown the pivoting point to be more close to the bow than indicated in the classical literature.

In Fig. 22 (a) and (b) the turning characteristics of the model with and without bilge keels are compared in full load and ballast

ten-!

ditions. The effects of the keels are quite different in the two cases. On full load the Model with keels has a much larger turning radius at large helms than the parent model. In ballast condition the presence of

thekeels.on the heavily trimmed model mainly increases the static

in-stability moment. A given helm will produce a tighter turn.

Test with captive models

A series of stationary oblique towing tests

with

a 'surface model

and a submerged double-body geosim are reported and analysed in (21). The tests were carried out

primarily:-To supply information on the influence of the free surface, in relatiOn to the application of slender body theory for Pre-dicting the lateral forces on the hull

To supply first and higher order stiffness and control deriva-tives for the models

To show the influence of draught, screw loading and bilge keels. In Fig. 23 a comparison between the yawing moments Ei; for the surface model at different speeds and for the double model is made. The linear moment derivatives show a steady rise with increasing model speed above

the zero speed or unbounded-fluid value Obtained for thedouble model.

The

double .model

was

divided at sections near the forward and after shoulders thus allowing the determination of the lateral force distribution.

7.

Systematic ExPeriments

For many years systematic series of Model tests covering different purposes and fields have been carried out: Many of the older publications

of SSPA deal with systematic model tests. Here may be mentioned the

Nordstrom Propeller. family (SSPA Publ. No.9)

with

general propeller

characteristics from 1946, the Lindblad bulbows bow studies (Publ. llos.

3

and 8) published in

1944

and

1948,

the Nordstrom systematic tests with

fast cargo vessels from 1948-1950 (Publ. .flos. 10, 14 and 16) and the

Warho).m coaster series from

1953

and

1955

(Publ. uos 24 and

55).

Below

will be given a .general survey of current extensive model series at SSPA, primarily within the fields of resistance and propulsion.

Merchant shin models...4c = 0.525 - 0:750

LF

A very extensive series of merchant ship models has been

running for

many years

and is still

in progress at SSPA. Fig. 24'gives an impression of

the volume of the work. It also includes references to publications.covering

different parts of

the, field. A total of

more than 100 ship models have

alread:-been tested in this family.

A careful reanalysis of the

material and

cross-plotting of the test

STATENS skEPPSPROW.dINGSANSTALT 13 Gateborg 24, Sweden

basic material for the 47

= 0.675

models. The residual resistance

pp

coefficients have been obtain from the model tests by Use of the ITTC

1957

ship-Model correlation line.,

' Tanker Model series

Edstrand (22) has given a review of-the older ,systematic series of

tests with tanker mOdels.carried.put during the years

1953-1956,

Complement-ary tests including different forms and dimensions have been carried out later.

Tests with a new family of tanker model's is in progress at present. ,The work is being .undertaken in cooperation with Swedish shipyards and

covers in the first stage a number of models within the ranges:-0.80< o;p< 0.84

5.0 < L/V

1/3<

5.6

.Series of high speed craft

A systematic series of tests with high speed craft is in progress. In the first stage a series of round bilge models is being tested within the

ranges:-3.0< B/T < 4.0

6.0< L/V1/3< 8.0

Special studies of the influence of draught, trim and spray'strips are undertaken.

Series of bodies of revolution

The mathematical representation of bodies of revolution-has,been treated by Wi1liams.(23). Based on his method a series of bodies of

re-volution

with

varying fullness has been deVeloped. Resistance tests, wake

Measurements, and self propulsion tests are being carried out with the models, The propeller diameters and positions are varied.

Fig. 26

from (24)

illustrates the great influence of the propeller

position on the propeller efficiency for bodies with prismatic, coefficients

o.70 and '0.80.

It has been found that for preliminary investigations the residual resistance of a-body of revolution may be determined from the formula

BtandardlEaRiLaE.-atreat.

A large series of propeller models with simple geometric shape,

has been manufactured primarily to

allow all the self-propulsion tests with the above mentioned

cargo ship and tanker model families to be carried out with propeller models of similar shape

allow systematic studies of optimum propeller diameter, number of blades and bladearea ratios in connection with commercial tests

be used for preliminary self-propulsion test for customers.

At present the propeller family consists of about 80

propeller models. Open water tests are carried out with all the propellers and

many of the propellers are being tested in the cavitation tunnel in

homogeneous flow as well as in different wake distributions. The

pro-duction of propeller design charts and cavitation diagrams based

on

the

test results is in progress. Special propeller .series

A number of new propeller families for. different purpose

(contra-rotating propellers, ducted propellers, low-noise propellers) have been

prepared and some preliminary tests have been carried out.

8. Shi

Trial and Service Analysis

The analysis of ship

trial and service results and the corresponding

study of ship-model correlation is of interest in all the different fields

discueSed in Section 3-6 above. This may be exemplified

the model and

and full scale investigations on a 9000 tens Swedish cargo vessel, described

in /25/.

The model tests

with this ship design

included:-Resistance and self-propulsion tests at different draught and

trim conditions (still water)

Self-propulsion teats among waves (head and following

seas)

Measurements of. wake distribution in the propeller field

Open water tests and cavitation tests in irregular flow

distri-butions with different propeller designs

Turning and stopping experiments with a self-propelled

model at

different draught and trim

Different methods for .analysing the results of 'measurements on ship

trials and comparing with the corresponding model

test.

results were

dis-cussed in /26/. This paper was prepared for the 9th ITTC in Paris, 1960.

Preliminary hypotheses with regard

to the

scale effects on the wake fractions

and the thrust deduction factors were empirically deduced.

In a Second paper /27/, primarily prepared for the 10th ITTC in

.

London, 1965,..-different

method's of correlating ship

trial

results with

mode/ test results presented in many countries were compared. The results of

a number of Swedish trial trips were analysed and the correlation factors

obtained were compared with the corresponding material from foreign

publica-tions.

With the most promising method the scale .effects are assumed to be

Concentrated

on.

the resistance and the wake fractions (until further

in-formation

is

available

with

regard to possible scale effects on the other

propulsive factors). The

method

is deSCribedih:dettail. in /27/ and similar:,

methods are applied with minor modifications by Danish, French and Japanese institutions. The method has been applied

to "Lubumbashi", Fig. 27.

Pre-dictions from the model tests have been.made'for a

number.

of resistance

correlation

factors,ACT and

wake Correlation factors (1-wi)/(1-ws).

The Ship trial spots for 15.1 and

16.5

knots have been plotted in the diagram,

from which the combinations, of

_JicT

and

J'P'Satisfying

the

trial

results

can be obtained. For the present case the correct values seem to be

ACT = 0935 - 040

J;',/ .3:= 0.97

- 1.00

STATENS SKEPPSPROVNINGSANSTALT 15

Gateborg 24, Sweden

Comparisons between geometridally similar ship and propeller models.

For the same type.of ship, full-scale- results are available from a

number

of

sister ships. These results- cover:-Speeds

trials-11(essureMents-Under service conditions

Propeller inspections (cavitation erosion studies) Turning and stopping trials.

Similar work Within the subjects propulsion, cavitation,.

sea-going

and manoeuvring is in progress

for

different types of ships and the material

obtained, is consecutively statisticallyanalysed.

slightly dependent on the speed.

Manoeuvring, ship turning circles

A simple semi-empirical relation for minimum turning diameters of single-screw motor ships based on theoretical consideration and experimental

results from ship manoeuvring trials was proposed in/25tand is illustrated

in Fig. 28. The diagram is useful for preliminary investigations.

9.

Final Remarks

The summary above is far from complete but it is the hope of the

author

that it

will give an outline Of

all

the different problems and

hypotheses that are being discussed and treated by the. research department of SSPA to.-day. Many Other projects and investigations could have been mentioned, for instance in the important fields of basic hydrodynamics and

hydrodynamic noise. Out of those current investigations some have been

chosen for a final

enumeration:-Basic theoretical studies on pressure distribUtiOn.in a thick boundary layer

Scale effect problems connected to model acoustic experiments Theoretical and experimental studies of singing propellers

Theoretical and experimental studies of partially supported

hydrofoil boats

10. References

/1/

JOhtsson,

/2/

Johns son.,

Dyne

G:

Lindgren,

Edstrand,

0.-A.: "An Examination of Some Theoretical Propeller

Design Methods", PUbl. No. 50 of the Swedish State

Shipbuilding Experimental Tank (SSPA), GOteborg, 1962.

C.-A.: "Comparison of Propeller Design Techniques", SSPA

Publication No. 52, Gbteborg, 1962.

"Berakning Ay dyspropellrar", SSPA Report No. 1325-1,

GOteborg, 1964. (Confidential).

H.: "ModelTestswith a Family of Three and Five Bladed

Propellers", SSPA Publication No. 47, Goteborg, 1961.

H.t "Photographing Propeller Cavitation on a 50.000-ton

d.w. Tanker", Shipb.. and Shipping Record, February 15,

London, 1962.

H.: "Cavitation Tunnel Tests with Merchant Ship Propellers",

Trans. I.E.S.S., Glasgow, 1961.

och akustisk observation avitavitationpa Olika nosformer",

SSPA Report No. K 53-1, Goteborg, 1963. (Confidential).

C.-A.: "Underlag for bedomning av ftirutsiittningarna for

uppkomsten av kavitation. LitteratursaMmanstallningi"

SSPA Report NO, K 54-19 GOteborg, 1963. (Confidential).

C.-A.: "Orienterande berdkningar betraffande

resorber-verkan hos en kavitationstank", SSPA PM No. K 64-2,

Giiteborg, 1964. (Internal).

N.H.; niotstAndsdkning och fartforlust i regelbUnden och

oregelbunden sjd", SSPA PM No. B 130-1, GOteborg, 1

964.

(Internal).

/11/ Bengtsson, B.G.: "Influence of.V and U Shaped Fore Body Sections

on Motions and Propulsion of Ship in Waves", SSPA

Publica-tion No. 49, Giiteborg, 1962.

/12/

Bengtsson, B.G.: "Influence of V and U Shaped Fore Body Sections on

Motions and Propulsion of Ship in Waves at Ballast Draught",

(To be published).

/13/

"Fidorsdk med torpedbatar.i Nave, SSPA Report

NO. 1076-1, Giiteborg,

1960, (Confidential).

/14/

"FOrsok i vagor med. fOrankrade modeller av "Belos" och projekterat

dykeri-och barjningsfartyg", SSPA Report No, 1018-1,

Goteborg, 1960, (Confidential).

STATENS SKEPPSPROVNINGSANSTALT 17 Goteborg 24, Sweden

/6/

Lindgren,

/7/

"Visuell

/8/

Johnsson,

/9/

Johnsson,

/10/ Norrbin,

'/15/ Norrbin, N.H.: "A Study of course Keeping and Manoeuvring

Perfortance",-SSPA Publication No.

_45,.

GOteborg, 1960.

/16/ Dyne, G.: "Olika faktorers inverkan p. undervattenskroppars dynamiska

stabilitetsegenskeper", SSPA Repbrt No. 1283-1, GOteborg,

1963. (Confidential).

-117/ Norrbin, N.H.: "Styrning ev torpeder" SSPA Report No. 1098-1-4,

GOteborg, 1960-1962. (Confidential).

/18/ Norrbin, N.H.: "On the Design and Analysis of the Zig Zag Test on

Base of quasi-Linear Frequency Response", Contribution

to the 10th ITTO, London,

1963.

/19/ Norrbin, N.H.: "The Methods used for the Tracking of Radio Controlled Models in the SSPA Manoeuvring Lake", Proceedings of the..

9th ITTC, Paris, 1960.

/20/ Nortbin, N.H.: "Circle Tests with a Radio-Controlled Model of a

Cargo Liner", SSPA Publication No. 53, GOteborg, 1963.

./21/ Nortbin, N.H.: "Forces in Oblique Towing of a Cargo Liner and a

. Divided Double-Body Geosit", (To be .published).

/22/ Edstrand, H.: "Experiments with Tanker Models". Trans. N.E.C.I.,

Newcastle Upon Tyne, 1956.

/23/ Williams,

A.:

"Mathematical Representation of Bodies of Revolution by Use of a Digital Computer," SSPA Publication No. 51, GOteborg, 1962.

/24/ "Systemetiska modellfdrsok med rttationskroppar. Undesdkning av en

rotationskropp med

0

0.8 och L/B # 7", SSPA Report No.

1261-2, GOtebOrg, 1964, (Confidential).

/25/ Lindgren, Hey Norrbin, N.H.: "Model Test and Ship Correlation for a

Cargo Liner, PropulsJ.oh, 0Avitation4 Sea-goingand Manoeuvring", Trans. R.I.N.A., London, 1962.

/26/ Lindgren, H.., Johnsson, C.-A.: "The Correlation of Ship Power and

Revolutions with Model Test Results", SSPA Publication

No. 46, GOteborg, 1960.

/27/ Lindgren, H.: "Ship Trial Analysis and Model COI-relation Factors",,

P. H. _(J/Q

0

FS ci- CD 0 II 0 ti ₁₁ 0

ti

_{CD CD ii} 0

:13 c+ H.

Input data for Part I

V ',IDTz

8.

P

ter density

Prop.4.bolow water surt.h Noon wake factor, wo Like distribution, wi Drag/Lift ratio for blade sections, estimated volt::: Circulation distrib.: Gmk(a04-alx+...) Calc.of Lad. velocities u., u,,First loops u =u,w0A $method or ind.fL-..ctor _{.method uA ..f(k014011,}

6

:Chooze a stalt value for max. profile thickness e or profile lenoth 1

?oether;ith

Ofrom 5 this ;ives 2/i and thus 1. Vox eff.camber

f

is also

off _obtained

Paint

I

Calculation of thruSt 7 8

A ppl leaf ion of'opllrox. curvature corr.-lives camber f

geom

Change e or,/

T froo agree.s, with Tinput' _{Print Cr}

Check ofiri

10

VI from 9 alrees with

r.

Dinput

Ctren;th Cal gives Ola It should be pot:Able to choriebot4eel

diff.calc.

procedures class, rules, theoretic

cab.

.Cas

Tea

Calcv/ation of' pitoh

lift C, L

cav.number

for all

coot Lone 11

More accurate curvature corr. gives final value of fgeom

To Part II

Calculate and nrint: Drag/Lift ratio for

blade sections

Thrust Power fficiency Profile t-bles _{7:eight of blade} Lzoment of inertia

lend

so on

Pori

;ID

,harF777in Gr.--1c(3----7721-73T17

Input data

for Part II

Data from 5 of Part I to,-;ether with allowable

strelv,s ,specifie

grwrity of propeller material,profile

Wetness distr. profile

spas lime

0.6"

0.4

0.2-4:0.0 ad kL. a6 0.4

/-0 0.1

02

0.3 0.4

05.

06

0.7 0.6

09

1.0

BLADE SECTION AarIR

Pig. 2.

Pitch ratio curves in ideal flows calculated according to

different lifting line theories. From /2/.

INOTATIONI

LIFTING SURFACE METHOD

APPROXIMATE GINZEL METHOD, k-VALUES FROM WA

lf if el 0 ECKH-MORGAN

GUILLOTON'S METHOD. SWIM BLADE EN'S METHOD II a

11

"

BLADE WITH SKEW

Fig. 3.

Camber correction factors calculated according to different

lifting surface methods. From/2/.

0!..

0.2

0.3

04

0.5

06

0.7

08

0.9 1.0

BLADE SECTION x. rIR

NOTATIONS LIFTING LINE METHOD

X-METHOD, HUB CONSIDERED

AIDUCTIOAI FACTOR METHOD. PROCEDURE ACC: TO LERBS. /AIDE F(A)

DIRECT INTEGRATION REF:

121 "

is

5

0

Resulting flow curvature in

the woke

Effective flow curvature in homog. flow

Flow curvature due to woke variation

7 \In the wake

In homogeneous flow

02

4.3

004 CUS

04

07

_0.8

_0.0

)(

Pig.4.

Momentary radial circulation

_{distribution and profile flow}

curvature in a wake. Blade position 150 starboard of the top..

1.0

5.

0

0.2

,

' ° '

V

\

. . . .

/

\

il

#

1

New method z

=

li

II1

z:5

₅

Induct, fact-method z=5

0.2

o.4

_0.6

_0.8

0.4

0.6

r 1 R

Propeller induCedaxial .and tangential velocity components.

From /5/.

IOKT

, 100K

_Q

?

₀

10

0.8

0.7

0.6

Q5

0.4

a3

02

0.1

Mean values, atm.

_pressure

Forward propeller

Mean values

_Cr:075

Aft propeller

-Design spot

I I I

'NJ

12

1,4

1.6

1.8

2.0

2.2

n

Fig. 6.

Contra-rotating 'propellers. Propeller characteristics.

9

1.0

Q5

0°

15° 30° 45° 50° 750 90e

Back cavitation

Dummy model -1;/-6-77ets

Smooth plate

\ Homogeneous Dummy mode/ f Jo9.637, C741

Fig. O.

_{Cavitation in a wake peak. J and}

_{g based on the mean velocit;!,}

1.0

(Homogeneous flow

--.Amoopb plat

Homogeneous flaw

0.5

Flu. 9.

-Plat

with nets

Dummy model

15° 300 450 600 750 90'

Plate with nets

Dummy model (Ja0.637, 0141

e41' 4 'ACst

A

Cavitation in a ,.7:fke.. De.k. J and a based

_{on the velocity in the}

90°

position,

o

VA

(0.9 R, 90).

vA /vA ta9R, 0°)

7

6

4

Homogeneous flow Dummy model

3

Plate with

nets

270°

.

_ .

2

z

'

Smooth plate

Homogeneous_

0*

15° 300 45° 600 75° 9d

Smooth plate

Bock cavitation

Plote with

nets-so,

0°

/

//

//

1

Dummy model

(J-a637,

.Pig. 10.

_{Cavitation in a wake peak. j and}

_{o based on the velocity in}

0,

Ship

propeller

_photographs

270°

.0511

tee

Fig: 11.

Model and ship propeller photographs for a tinker ship.

Ott 0 I.J . 0

0

Eg 0 11, Fi 0 Co (D 0

0.9

0.7

0.5

4 3 f'''i71.;'

*SP

'1,Y I 7,7111114:54)

Reg/ors for

bock cc vi tali

1 I I_ ,I I

360°

270°

180°

90°

I I. I I I I

o°

Top

o°

270°

Blade No. I

after

2 years

Eros/on

rqi4

O. /0

2

110

15

15

Fig. 14.

/

/

,

.L

050 0.75 ICK) 125

1.50

225

Wove length 'fraction,

_

Fig. 13.

_{Comparison of ship speeds in regular head waves with h=0.025 L}

fore. 0.794 models: Still water torque of

model with bulb at

16.6 knots maintained. Froth /12/.

U sections

\U

sections with bulb

Still water torque

maintained

Measured

Abkowitz

Wave lenght froction,

A IL

ComrCarison of self propelled ship Speeds in

_{waves as measured}

and as .determined from towing tests according to Abkotitz and

Bengtsson. From /12/.

Still water rate of revs. maintained

Increase of resistance due to waves,

RC

(d)

Fig. 17.

Definition of steering indices obtained from turning tests.

.1111ilax.,advance.11=radius of steady turning circle.

From /20/.

(a)

(b)

0

lpp

0.2,

_0.3

_0.4

_{0.5 0.6}

_0.8

_1.0

_1.2

_1.5

gs

27r/period

in ship lengths

sailed

Fig. 16.

_{Copy of transparency to he used with Fig..}

_{19 for rapid}

evaluation of first order system gains from frequency

_response

data. From /13/.

3

1

I

I I

Rat the amplitude ratio of

course angle' rudder angle

19.

_{Diagram for plotting frequency response or modified zig}

_zag

test data. From /18/.

0.3

0.2

WV

0.8

0.4

0.5 0.6

=

2771

period in ship length sailed

rig. 20. _{Plotting of triangulation records. From /19/.}

op_

%MM. 611.1MPta.

Without bilge keels

With bilge keels

0 0,1 0,2 0,3 _{OA 0,5}

0,6 Lpp Rc 0,7

1_111

1

00 8,J 40 20 10 8 7 6 5 ₄

2RcApp

3

Fig. 21. _{Pivoting point position forward of}

aft perpendicular OP in steady turning. From /20/.

0,7

Load draught

PORT HELM 0,4 4e 3e 2e Bellow? drchight 0,7 0,6 0,5 0,4 0,3 0,2 1 1

I1

1 40° 300 200 100 PORT HELM 0.2 0,1 1 W 0,2 0,5 0,4 0,3 0,2 0,1 0,1

a)

-0,5 -0,6 0,2 0,3 OD Lpp AD STARBOARD HELM -10° -2 -300 - 40° LPP _Without

if

With

blip keels

bilge keels

STARBOARD HELM

d

-1cP - 200 - 2)° - 430 .0,1 I 1 i I 1

- 0,1 - 0,2 - 0,3 - 0.4 - 0,5 - 0,t,

Without

_WWI,

_{ft With}

bilge

bilge bilge

- 0,4 _{keels keels keels}

L p p

--C) 0,5 ' ) (

Fig. 22. _{Turning circle characteristics for}

model on full load and in ballast as affected by bilge keels. From /20/.

1 ₁

-0.4 - 2,5, -0,7

-0,1 I

-Di -0,2

0.03

44.

t4,

0.02

1.1)

z

0.01

Surface model

4

6

8

10

12

Yaw angle, /3

Fig. 23.

Comparison of yawing moments for surface and double models.

0.75

P.

0.70

,J1

0.

0

CI%

r-r4. ta

0

0

0

0

-SSPA Publ.

No..42(19581\

No. 41 (1957)

No. 39(19

40-0.0

0

5.0

en. Ct)

Sign

No. 0 (1948)

\

0

-0

No.16 09501

No. 38 (19561

0 One

model tested

-- Older families with

different

bOsic form

-No 14( 491

5.5

6.0

6.5

,

.3

Length displacement ratio, Li

1711

CR

I I I I 1

Of 9

0.20

0.21

022

0.23

024

0.25

026

0.27

028

FnL

Fig. 25. Residual resistLnce coefficients for the basic d-pv= 0.675 series.

L

k

as

0./L

0.2L

:31 (,)

0.9

.0

(.12

0.8

0.7

(I)

0.6

0

0.025 0.05 0.075

L

L

_

Fig. 26.. Bodies of revolution. Influence of after body fullness and

propeller position- on the propulsive efficiency. From /24/.

\O =0.80

0=0.70

I I

P

_'

HP 7000 3000 12 10 09 1.Ik 0.8 x a7 8 ft. 0.6 41k as

411

0.4 7.; 0 66-02 0.1 03

90

Trial

15.1 knots

0

0.4 100 05 THot R5.5 knots

-3

,.0.14

4GT d3

_{0.z 17.}

,

0,-4GT

3

0 a. 3

i°

Asq0.2 V = 15.1 knots V= 16.5 knots 110

n, rIMin.

Fig. 27.

_{"Lubumbashi". Predictions and ship trial. From /27/.}

Li

,o Full drought

0 Ballast drought 06 07 0.8 Scale of parameter, 4.- 12' r-r- 67

Fig. 28.

_{Semi-empirical relation for minimum}

_{turning diameters of}

single screw motor ship with one rudder. From /25/.

Statens Skeppsprovningsanstalt (Historik, atltnhn planering, kostriader: Principer,

mñn beskrivninge Nagra sy-npunktor pa byggnadapmblemet: Rifumanis konstruktiort

oCh utfOrande.; Den instrumentella utrust-ningen; Den clektriska utrustutrust-ningen; tipp-gifter, organisation) [Summary in English),

av 11 uno HA M1? M11 A it, _{H. P. NORDSTROM,}

M. WERNSTEDT, S V EN' 14 ITLTIN, R. ROD

-sTni5m, KARL TISELIVS, 1942. Kr. 5: -.

Forsiik mad fiskehatarnodeller [Tests with Fishing Boat Models, Summary in English]

av H. F. NORDSTROM. 1943% Kr. 2: -.

Experiments with Bulbous Bows, av

AN-DERS LINDBLA D, 1944. Kr. 2: -.

Propellers with Adjustable Blades, av

H. F. NORDSTROM, 1945. Kr. 3: -.

Nogle Praktiske og Teoretiske

Underscigel-ser om Modelpropellere [Some Practical and

Theoretical Invastigations of Model

Pro-pellers, Summary in English], av JORGEN

MARSTRAND, 1945. Kr. 3: -.

The Effect of the Air Content of Water on the Cavitation Point and upon the Charac-teristics of Ships' Propellers, ay. Harts ED-,

smarm, 1946. Kr. 4: -.

Modellforsok med en farja [Model Tests with a small Ferry, Summary in English], aV

H. F. NORDSTROM och E. FREIMANIS, 1947.

Kr. 1: 50.

Further Experiments with Bulbous Bows,

av ANDES LINDBLAD, 1948. Kr. 2: -. Screw Propeller Characteristics, av H. F.

Noxnernbaa, 1948. Kr. 2: -.

Some Systematic Tests with Models of Fast

Cargo .Vessels, av H. F. NORDSTROM, 1948.

Kr. 3: -.

The Electrical Equipment of the Swedish

State Shipbuilding Experimental Tank, av

KARL TiszLrus, 1949. Kr. 4:

-.

The Resistance of a Barge with the Bottom Air Lubricated, av 1-1Ave Ens-maim' och

RAGNAR RODSTROM, 1049. Kr. 2:

-.

Medstremskoefficientens AfhEengighed af

Rorforrn, Trim og HEekbelge [The

Depen-. (fence of Wake on Shape of Rudder, Trim and

Stern Wave, Summary in English], av SPEND

AAGE Has.vaLn, 1949. Kr. 5: -.

Further Tests with Models of Fast .Cargo

Vessels, av H. F. Nonnsxntim, 1949. Kr.

2: -.

13. Cavitation Tests with Model Propellers in Natural Sea Water with Regard to the Gas

Content of the Water and its Effect upon Cavitation Point and Propeller Charac-teristics, AV HANS EDSTRAND, 1950. Kr.

Systematic Tests with Models of Cargo Vessels with ô=0.575, av H. F.

NORD-STROM, 1950. Kr. 2: 50.

Propulsion Problems Connected with Ferries,

av H. F. NORDSTROM oak HANS EDSTRAND,

1951. Kr. 6:-.

Model Tests with Turbulence Producing Devices, Etv H. F. NownsTnOm °eh HANS EDSTRAND, 1951. Kr. 10: -.

Seine Tests with Models of Small Vessels,

nv 1-1. F. NcutosTROm, 1931. Kr. 5: --. Model Tests with Icebreakers, av H. F.

NORDSTROM, HANS EDSTRAND OCh HANS

LINDGREN, 1952. Kr. 8: -.

Om djupgaendete inflytande p propulsions-egenskaperna [The Influence of Draught on Propulsive Qualities, Summary in English],

ay HA/PS EDSTRAND, 1952. Kr. 4: -.

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Propellers; AV HANS EDSTRAND, 1953.

Kr. 5: -.

23.. Experiments with Tanker Models I, av

HANS EDSTRA.ND, E FRErMANIS 00h HANS LINDGREN. 1953. Kr. 4: --.

Nagra systematiska foralik mod modeller av mintire kustfartyg [Tests with Models of

Coaeiterti, Summary in English], ETV AXEL 0.

WARITOLM, 1953. Kr. 12: -.

The Transverse Stability and Resistance of

Single-Step Boats when Planing, av R. ROD-STROM, HANS EDSTRAND oak H. Baarr, 1053. Kr. 6: -.

Experiments with Tanker Models II, ax

HANS EDSTRAND, E. 1'11E111/ANIS OCh HANS

LINDGREN, 1953. Kr. 4: -.

Full Scale Tests with the *Wrangel* and Comparative Model Tests, av H. F. NORD-STROM, 1953. Kr. 12: -.

On Propeller Scale Effects, av H. F.

Noma-STROM, HANS EDSTRAND OCh HANS

LIND-GREN, 1954. Kr. 4: -.

Experiments with Tanker Models III, av

IIANS EDSTRAND, E. FREIMA.NIS OCh HANS

LrtmoR.x.x, 1954. Kr. 6: -.

Resistance Experiments with Divided Ship Models, av R. RtiosTai3m, 1954. Kr. 2: -. On the Influence of Form upon Skin

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HANS EDSTRAND OCh HANS LINDGREN,

1954. Kr. 4: -.

Sta.tens Skeppsprovningsanstalt (The

Swe-dish State Shipbuilding Experimental Tank) in Goteborg. A Short Account of the

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Organisation, av H. F. Norton-10m, 1954.

Kr. 5: -.

The Influence of Propeller clearance and Rudder upon the Propulsive Characteristics, av H. LINDOREN, 1955. Kr. 4: -.

Seventh International Conference on Ship Hydrodynamics; Reports, Discussions and Conclusions, av H. F. NORDSTRoM ooh

I-1ANS EDSTRAND, 1955. Kr. 25: -.

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HANS LINDGREN ooh AXEL 0. WARTIOLM,

1955. Kr. 8: --.

Experiments with Tanker Models IV, air HANS LINDGREN, 1956. Kr. 6: -.

Experiments with Tanker Models V. av

HANS EDSTRAND, E. FREIMANIS och HANS

LINDGREN, 1956. Kr. 4: -.

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op7,=0.675, Part I, av E. FREIMANIS och

HANS LINDGREN, 1957. Kr. 8: --.

Tests with Geometrically Similar Models of the Victory Ship, av HANS LINDGREN °CIL E. 13.);utNE, 1957. Kr. 6: -.

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opp=--0.675, Part II, air E. RanimArtis och Harm LINDGREN, 1957. Kr. 4: -.

Systematic Tests with Ship Models with opp=0.675, Part III, av E. FnEndarns och HANS LINDGREN. 1958. KT. 5: -.

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A Study of Course Keeping and Manoeuv-ring Performance, air Nits. H. NORRBIN,

1960. Kr. 12: --,

The Correlation of Ship Power and

Revolu-tions with Model Test Results, air Harts

Limp (MEN och C.-A. joartssort, 1960. Kr.

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Cavitation Tunnel Tests with Merchant Ship Propellers, av HANS LINDGREN, 1961. Kr.

8: -.

Influence of V and U Shaped Fore Body Sections on Motions and Propulsion of Ships in Waves, air BENGT BEHGTSSON,

1962. Kr. 10: -.

An Examination of Some Theoretical

Pro-peller Design Methods, av C.-A. JORNSSON,

1962. Kr. 12: -.

Mathematical Representation of Bodies of Revolution by Use of a Digital Computer,

av AXE WILLIAMS, 1962. Kr. 8: -.. Comparison of Propeller Design Techniques,

av C.-A. JOHNSSON, 1963. Kr. 10: -.

-+53. Circle Tests with a Radio-Controlled Model

of a Cargo Liner, air Nina H. NORRBIN, 1963.

Kr. 17: -.

54. Ship Trial Analysis and Model Correlation

ALLMINNA RAPPORTER

FRAN

STATENS SKEPPSPROVNINGSANSTALT

Nr

Virvelteorien och:dess tilldmpning yid berakning av moderna

fartygspropellrar, 6.Y HANS LINDGREN,

1955.

Propellerberdkning enligt virvelteorien.. Rdkneexempel

och hjdlpdiagrat.1 av HANS LINDGREN och C.A...JOHNSSON

1956.

Problems Associated with the Obtainment of Two-Dimensional

Turbulent Skin Friction Data, av R.L. GAMLIN,

1957.

-Statens Skeppsprovningsanstalt. Med historik och kortmentarer till skeppsprovningsteknikens principer,

Ay HANS EDSTRAND,

1958.

FOrslag till program fOr gir- och ztyttingsprey med handels,

fartyg. Med ett tillägg cm fartygets tOrelseekvationeti

ay

NILS.H. NORRBIN,

1959.

Nomogram for prelimindr effektberdkning for kustfartyg, ay

- HANS LINDGREN och E. BJARNE, 1959.

Styrning yid

14g

fart. Problem och hjdlpmedel av NILS H.

NORRBIN, 1964.

8. Current Research Work of the Swedish State Shipbuilding