Twenty years of complex hydrodynamics research model tests and engineering consultancy 1971 - 1991

ABSTRACT

The paper related to the 20th Jubilee of BSHC gives a brief review of the development of the period discussed till now. During this period the facilities of BSHC were designed, built and put into operation. BSHC was created as an independent institution for investigation and development and considerable research programme has been implemented. The characteristics of the results till 1976 when the basic facilities of BSHC were put into operation, as well for the period respectively, till 1981 and till 1986, is quite generalized because these major results were presented widely and in details at appropriate Jubilee scientific sessions held by BSHC with significant international participation. To make the orientation of the development till now sufficiently full and clear without using the references in this paper, illustrations, block-schemes and tables are used to summarize the main outcomes also for the period till the Jubilee session held in 1986 of the permanent international seminar. After discussion of the etage-by-stage development a generalized information is given for BSHC wide-ranging research programme, the methods and technique developed, BSHC practical programme, the practical results and the other major aspects determining the character of the last 5-6 years of the activities performed. A brief information is also given about the actual problems, changes and trends of the future investigations.

rWIJTV VEE DF cDI1FLEX

DFDDVNSfN1 I c

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FJD E:I1& i I%JEF r

C D'I8*JL -r

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( 1

7 1- 1 ?.c?

i)

P. A. Bogdanov

Bulgarian Ship Hydrodynamics Centre Yama 9000, Bulgaria

1. INTRODUCTION

About 20 years have passed since the establishment of a division on ship hydrodynamics in the Ship Design and Research Institute in

yama

in November 1991, practically independent and headed by th

author of this paper, together with the signing by the Bulgarian government of an agreement for cooperation with the United Nations Development Programme CUNDP) and the selection of a building site for design and building of a relevant laboratory -experimental complex. During this period the design, the building and the putting into operation of the multipurpose experimental complex of BSHC were implemented with rapid rates, also modern methods and techniques of the hydrodynamic investigations and complex ship model tests and other floating structures were adopted and developed, as well as investigations and tests of structures of the coastal marine hydrotechnical construction works were realized.

Systematically information was published and/or presented regarding the activities and the results achieved at the 19 sessions of the Scientific and Methodological Seminar of BSHC practically held annually starting since 1972, at ITTC and other national and international forums.

The results of the design and development of BSHC was especially well presented at ITTC forums in 1972, 1975 and

2, 2

co Deift

1981 tl,2,34IItAth seminar

session

(held

in

S.ptftmber

1975) with considerabit

int.rnetipnal.par1r

and at the VI-th

session

(in connection

with

the

cerimony

for

the

putting

into

operation of the I-st stage of BSHC complex).

At the Jubila, sessions of

the

seminar

held,

respectively

in

1981

(in connection

with the tenth Anniversary) ard in

1906

(in

connection

with the

fifteenth Jubilee) the

activities related both to the development of

the method, and techniques, as well as to the

wide-ranging

h programme developed

(4,5]

were

broadly

reflected.

At

these

sessions the author tried by

plenary

papers

to

present

the

main

results

of principal

character for the relevant

periods

achieved

with the effort, of BSHC as a whole.

General

information

about BSHC

activities

was

reflected

also in the holding of a number of

international

authoritative

forums,

for

ecamp1e, IPIAEM Congresses

in 1978 and 1981

(7,83, PRADO Symposium in 1983 [10] and later

in

1987, CADMO'BÓ Conference (11], STAR'90,

etc.

Since 1981 the active

participation

in

the

ITTC programme has

allowed

that some

easential results of BSHC activities could be

reflected systematically in the papers of the

main ITTC

Technical

Committees and

the

different

aspects

of

the

activity

and

achievements

of

BSHC

could

find

wide

presentation

in

the

form

of

written

contributions and discussions

published

in

the

second volumes

of the ITTC Proceedings

[11, 12, 13 and 14].

Besides at th.

forums mentioned above

and

other events permanently, systematically

and

sufficiently

_{exhaustively the results}

achieved by

the

different

divisions

and

different scientists of the Centre have

been

rfJected

and

given

due credit.

Among the

muLtitude of

such

publications

some major

or,e

will be cited in this papar further on.

From what has been

stated

so

far

it

becomes

clear

that

_{it is difficult for the}

author to reach the aims of this paper, which

can be summarized, as follows:

-

not

to

go

over

_{the information already}

given in the past in details but only more

essential

aspects

to

be reflected using

block-schemes, tables and

other

ways

of

presentation

of

the

approaches

and/or

results;

-

not

to

repeat

the

evaluations

already

given

but

only an attempt to be made for

their generalization from

th.

standpoint

of the present difficult time.

There

are

also

other

difficulties

connected with the effort of

the

author

to

submit

a

_{paper with a possibly small volume}

on the on. hand, and on the other

one

these

difficulties

are

related

to

the

lack

of

state-of-art papers in HADMAR'91 Programm. in

the

different

fields of BSHC investigations

and development in the 20-year

period

under

review,

as was

_{initially envisaged.}

_These

difficu1tir

are valid

in

the

same

extent

both

for

the

review of the period that has

passed, as w.11 as though

in

a most

generalized

form,

for

presentation

of the

trends of the future development.

2. SHORT HISTORICAL REVIEW AND MAIN STAGES

OF BSHC DEVELOPMENT

The

idea

of

establishment

of

a

scientific

and

experimental

centre on ship

hydrodynamics

occurred

in

1957 when

the

specialis!s at the Design Office of the Varna

Shipyard servicing also the

other

shipyards

in

this

country

wer,

entrusted

with

a

significant programme for design of new ships

with

a

different

purpose. The

increased

demands

of

_scientific

_servicing

_of

_the

shipbuilding

and

the

marine

industry

stimulated the study of the idea of

creating

experimental

_{facilities, especially since in}

1962 when a

Ship

Research and Design

Institute

was

et

up on

the basis of the

above Design Office

in

Varna.

Since

this

y.ar

[4,5)

the

I-st

stage of BSHC history

should be considered to

have

started

(i.e.

with

a

fore

background

till

1971 when

practically an independent division

on

ship

hydrodynamics was

created)

and

chronologically 4 stages should be

discussed

in

accordance

with

the

character

of

the

determining activities

and

events

at

each

particular stage.

2.1. THE FIRST

STAGE (1962-1976) covers the

period of study, design and establishment

of

the

laboratory-experimental

complex and

concludes

with the

official

putting

into

operation

in

1976

_{of the deep water towing}

tank,

the

_cavitation

_laboratory,

_the

experimental

workshops,

the

engineering

building, the conference hall, etc.

The mor, characteristic

_activities

_and

events

for

this stage can be reflected most

- the wide study of the f oreign experience of leading countries in this field,

including study tours, long-term fellowships, participation in international conferences and symposia, obtaining of expert consultations, etc. The study of the advanced experience became particularly systematic and purposeful after the signing of the agreement of the Bulgarian government with UNDP and covered the problems of the design, building and investigations;

- the successful design of the laboratory-experimental Complex on the basis of an adequate methodology. (The conceptual project was approved by the government on 31 January, 1973 and after that in the course of the detail design stage-by-stage implementation of the construction works was undertaken);

- establishment of the laboratory -experimental complex in comparatively short terms and adoption of the capacities, as well as adoption of the methods and techniques in the course of the putting into operation of the experimental workshops (1974), the cavitation laboratory (1975) and the deep water towing tank (1976);

- execution of design and consultant services for the industry on the problems of ship hydrodynamics.

- dynamic development of the staff personnel and implementation of a purposeful programme for training of all categories of BSHC staff. If in 1962 there was only the author of the present paper and in 1964 started his activity Mr.Stephan Goranov (directly engaged in the studies for the creation of the experimental facilities), towards the end of 1971 the number of the personnel in ship hydrodynamics was raised to 13, and to the end of the period under review it became about 200 among which there are 12 persons with scientific titles and degrees (7). The long-term fellowships in Japan, Western Europe and the Soviet Union, the international expert assistance, as well as the intensive international contacts by study tours in different countries allowed not only to design, set up and adopt a national multi-purpose complex in a

comparatively quickly but also immediately upon the putting of the facilities into operation to proceed immediately to

performance of model tests for the needs of the induStry and implementation of

relevant h projects.

- organization since th. beginning of 1972 of the international permanently acting scientific and methodological seminar on methods and means in ship hydrodynamics and holding of 6 sessions during the period discussed. The role of this seminar was constantly increasing both for preparation of the personnel, as well as for development of international contacts and cooperation and for publication and discussion of the results achieved in the

activities of BSHC;

- participation of BSHC in ITTC (since 1972 with delegates and since 1975 as a member-organization in general and in Che

hIC Advisory Council in particular).

Perhaps the greatest advantage of the cooperation with UNDP for the first and subsequent stages (till the present Jubilee symposium) is the establishment and development of international personal contacts of BSHC staff with leading scientists and specialists from all over the world. These contacts are a decisive factor for the obtaining of considerable intellectual input by transfer of modern achievements and experience both in the choice of the conceptual and specific solutions of the problems related to the experimental facilities, as well as in the performance of hydrodynamic investigatione and model tests

Some of the major aspects connected with the first stage of BSHC development are clarified further on in the paper, giving relevant more detailed information and/or data.

The creation of BSHC could not be possible without the establishment of cooperation with UNDP by the author's initiative (executing a relevant project), which allowed a set of problems of sciertific, technological, organizational and financial character to be successfully

settled down in a comparatively short time.

2.2. The SECOND STAGE (1976-1981) covers the period of further building till 1979 of the shallow water towing tank and the seakeeping and manoeuvring tank, the equipment and the facilities put into operation towards 10 October, 1976, as well as the adoption of

their full capacity. This period can be characterized most generally, as f ollows

- expansion of the range of the performed perspective investigations, model tests, consultant and other services rendered for Bulgarian customers and after signing of a contract with Krylov Ship Research Centre, at the beginning of 1978, execution of a certain amount of contracts by order of foreign customers

- development and system&tic expansion of the computer application in the engineering activity and the experimental investigations (Fig.1);

- constant consolidation of BSHC and its establishment with an independent status (since 1 July, 1977) as a centre with an international importance;

- further development of the cooperation with IJNDP in the form of two relevant projects aiming BSHC consolidation and adoption of modern methods and techniques of ship handling and manoeuvrability (approved since 1978). These projects as well as the bilateral cooperation constantly increasing during this period, allowed further development of the international contacts, execution of joint

research programmes, etc.;

- further increase of BSHC staff qualification, improvement of BSHC structure and continuation of the execution of the programm. for long- and short-term fellowships;

- activation of BSHC participation in ITTC conferences and progressing participation in other international forums, organization and successful holding of the IV Congress of !MAEM (in May, 1987), etc.;

- increase of the international prestige of BSHC seminar and the number of the foreign participants and publication of the Proceedings of the seminar annual sessions

and expansion of the international information exchange.

This stage of the development of BSHC activity has been _{particularly fully} reflected in the session held in November, 1981 dedicated to the 10th Anniversary of BSHC duri ng which more than BO papers were presented C4]. _{A number of publications were}

produced and/or papers presented at different international forums about which some summarized data are given further on.

2.3. The THIRD STAGE (1981-1990) is the period of BSHC development till its inclusion in the frames of the Bulgarian Academy of Sciences since the beginning of 1990 with a new and more wide subject of activity, with more fundamental character of the investigations performed.

Perhaps this stage is the most fruitful one in the development of BSHC because (after the solution of the major problems related to the development of the experimental technique, the computerization and the completion of the equipment and the facilities) the efforts and the activities were concemtrated towards the execution of primarily a wide-ranging h programme. At this stage the following trends of development and results of BSHC activities could be generalized _{as characteristic and} determining

- execution of serious research projects primarily in cooperation with research organizations from different countries, including by orders of foreign customers;

- _{successful performance of a}

considerable amount of model tests and consultant services for the Bulgarian industry and for foreign companies;

- creation of a hydraulic laboratory and implementation of a number of projects for optimization of the facilities for coastal protection (since 1981);

- _{continuation of th, cooperation with} UNDP and _{active participation in hIC, further} regular holding of seminar sessions with significantly increased international interest towards them;

- expansion of the participation in international conferences, symposia and successful organization of the Fourth International Symposium on Practical Design of Ships and Mobile Unite (PRADS'89) in Varna in October, 1989;

- establishment of cooperation with UNIDO (since 1983) and execution of. several expert missions _{and preparatory projects} for rendering of technical assistance to developing countries from different regions, etc.

During this stage of development considerable experience was gained, the prof essionalism o-f BSHC personnel increased and in all aspects of the ship hydrodynamics complex approaches based on the application of theoretical and experimental development of the computerization were adopted, as is clarified further on the present paper-.

.4. The FOURTH STAGE (1990-1991) appears to be th. last one of the periodization conditionally accepted in the present development. Qn the basis of a decision taken by the Bulgarian government since 1990 BSHC has been incorporated in the system of the Bulgarian Academy of Sciences (BAS) with a changed and more wide-ranging subject of activity than in the previous period.

The crisis in the national economy due to the disintegration of the Council for Mutual Economic Aid (CPIEA) and other reasons of global character, as well as structural

changes in the industry, would have obstructed very strongly the financing not only o-f the perspective investigations but

also and in general the activity of BSHC if

the problem of BSHC transition to BAS had not been successfully settled down. For this period it is typical, as 4ollcws

- adoption of new themes and topics (in accordance with the changes and broader objectives o-f BSHC) related to the

fundamental and applied investigations in ship- and aerodynamics and solving of problems in the field of ecology and environmental protection;

- continuation of the investigations in ship hydrodynamics with emphasis on expert onboard systems, simulators and other integrated products for possible efficient realization on the home and the international market;

- overcoming of the lagging behind of the personnel with regard to the attainment of scientific titles and degrees in accord with the new requirements;

- enhancement of the participation in the training of engineering specialists;

- keeping of the staff of the experimental workshops and the remaining aid personnel by execution o-f services and tasks not

related to BSHC research activities, etc.

The transition to BAS has allowed the economic and financial problems to b. solved considerably more succe,sful than the research organizations could do this in the system of the national industry. However, it becam. necessary the personnel amounting to a little over 300 persons to be gradually reduced in the last 3-4 years to about 230 persons, among them 73 being research scientists at present.

3. BRIEF DESCRIPTION OF BSHC RESEARCH PROGRAMME IN THE PERIOD 1971-1991.

Th. activities described in the previous section of the paper about the four conditionally determined stages of development are evaluated by their structure and relative share in accordance with their purpose tentatively in terms of cost and/or labour consumed in Table 1.

Table 1. Structure o-f the Main BSHC

Activities in the Period 1971-1991

No. Types of Activities and Direction of

Realization

I. Design and develop-ment of the facili-ties and the technique

Stages of Development

1962 1976 1981 1990 1976 1991 1990 1991

78% 19% 6h SV.

Fundamental and per- 16% 42% 43% 60% spective

investiga-ti one

Applied investiga- 6% 15V. 16% 18% tions and consultant

services for Bulga-rian companies

Research projects for foreign customers

Model tests and ser-vices for foreign customers

14V. 24% 15%

10% 11% 2V.

From Table 1 it can be seen that during the whole period it was possible to ensure a considerable share of the tasks on research and development with perspective and fundamental character. This has allowed the

comparatively quick design, building and adoption of the multi-purpose complex on the one hand, and on the other on., th. inclusion of actual problø.s in the main fields of the ship hydrodynamics within th. scope of the topics covered, thus ensuring development of BSHC ahead of the present time with regard to the national and international demands and orders f or invest i gat ions and model tests.

Th. relatively great amount of orders for foreign customers and the full satisfaction of the national demands are explained by th. high competitive power of the facilities, methods, technique adopted and applied by BSHC, as well as by th. staff professionalism. Descriptions of the facilities, methods, techniques developed by BSHC, as well as considerations for their advantages are presented in a number of publications £103, £113. C1S+21], £26], £273, etc. That is why in this paper these aspects have not been reflected in details but only the results in th. major trends of the development till now have been summarized.

To get a general idea Table 2 can be used showing the composition and the main particulars of BSHC experimental facilities.

3.1. Develooment of Comolex Aooroaches. Comouterization and Aoolication of Comoutat ion Methods

After putting into operation of the facilities according to Table 2 during the last 10-15 years BSHC has rendered complex hydrodynamic theoretical and experimental investigations and model tests for optimization of the technical solutions for ships and other structures and objects of the shipbuilding, the water transport, the fishing fleet, the ocean engineering, the marine hydraulic construction works, etc.C7).

The investigations and the application of the complex approaches for optimization of the project solutions are facilitated besides by the rational laboratory-experimental complex, also by the role of the computerization attributed to the automation

of the engineering activity and the scientific experiment. BSHC experience has confirmed a number of advantages of the computerization, reflected on Fig.l and treated in a number of BSHC publications Cli], (30], [31], (32]. etc. In this regard a hiearchical system has been created using 32-bit mini-computers, micro- and

Table 2. Composition and Main Parameters of BSHC Experimental Facilities

i. Deep Water Tow- 200x16x6,5 No.1 6./s ing Tank (1976)

Shallow Water 200x16x0+1,5 6./s Towing Tank

(1979)

Manoeuvring & 64x40x2,5 free-running Seak.eping Tank tel ecommand

(1979) models

Hydraulic Tank 15x15x0,5 moveable

(1980) wave maker

Open Water Area 170x160x3,0 as per i.3 (1982)

Hydraulic Open- special as per i.4 Air Tank (1984) form 410m'

Open-Air Wave 2,8x0,8x0,8 as per i.4 Channel (1984)

Cavitation Tunnel 0,6x0,6 f low (1976) with Extra 1,45x0,7 velocity

Working Section i Sm/s

(1989) Sm/s

Wind Tunnel elliptical

test section flow 9.1 Mini WT (1991) 0,8x0,45 velocity 9.2 Large WT-1 (under 4,0x2,33 100./s

construction)

Table 3 gives generalized data about the developed computer programs applied in different fields, so that for the major ones more detailed descriptions and data are contained in BSHC Catalogue of Application Software [323.

For geometrical modelling and ship hull design a program package SYSD has been developed [33, 34, 352 in view of solving the

following major problems:

- generation of the basic hull form;

- mathematical description of the ship hull; Max .Spe.d No. Facility and Dimen- of Towing Year of Putting si ons Carri age into Operation (.3 and Other Parameters

- matrix calculations Carca, velum,, determination of the hydrostatic moment, wetted surface), preparation of NC data.

As for the role of the computerization at BSHC beside. from Fig..1 and the above

Table 3 an idea can be obtained from Fig.2, showing the principal scheme of the information flows in the theoretical and experimental investigations in the field of ship hydrodynamics in general, and in BSHC activity in particular C101].

As has been already mentioned above the computerization at BSHC involves both the automation of the engineering activity, as well as the automation of the scientific experiment. ¡n essence there are measuring and computation complexes C4,53 developed for each experimental facility created on a modular principl, with possibilities for further expansion. Fig.3 illustrates the block-diagram of the automation process of the experiments in the deep water towing tank (102].

A high degree of automation has been reached in the manoeuvring and seakeeping tank, as is evident from Figs.4 and 5, illustrating respectively, the automation of the manoeuvrinç and seakeeping tests and investigations (15, 19]. High is also the extent of the automation of the investigations and tests performed in the cavitation tunnel, while as for the automation of the experiments in the shallow water towing tank Cafter unsuccessful efforts of using micro-processor technique) the experience gained in the deep water towing tank has been applied.

In connection with the acoustic investigations performed in the cavitation tunnel the computerization appeared to be also an effective means for data acquisition, processing and analysis (94], etc. For this purpose computer programs have been developed and approaches have been applied as illustrated by the block-diagrams according to Figs.6 and 7 (103].

Further on approaches applied and/or results achieved in the different fields of

*he ship hydrodynamics are summarized.

The main problems of the resistance evaluation of a ship with specific hull lines and their optimization are the exact prediction of the full scale resistance, the improvement of the efficiency and development

7

Table 5. Computer Programs and Products for Automation of the Engineering Research and Experimental Activity

Period of Creation

of calculation methods by the wave theory and the theory of the boundary layer. Fig.8 shows the main methods and means developed and applied at BSHC in this field. Algorithms and computer programs have been developed for the most wide-spread methods for determination of the ship resistance (32]. Due to the difficulties related to th mathematical modelling f the tot resistance, in the theor.tical investigations and in the physical modelling the resistance

components are discussed separately.

A subject of intensive investigations is the theoretical model of the wave resistance because the methods created still do not allow determination of the wave-forming resistance with sufficient accuracy. At BSHC a program has been developed for calculation of Michel's integral for arbitrary ship form (34] and computer implementation of Total 1971-Bl 1982-91 16 21 37 24 35 59 8 28 36 11 26 37 17 22 38 15 54 69 91 195 276 Subject No. Field Flow around bodies and boundary layer Complex scienti-fic and technolo-gical calculations

Programs for pro-peller and hull design

Systems for stan-dard tests and for the scientific experiment

Application of numerical and

sta-tistical methods

Engineering graphics, etc.

Suilloton's _{method with satisfactory fairing} cl the numerical and experimental _results

at large Froude numbers 1:37). _{Applying the}

linear theory of the wave _{reist.nce after} some simplification assumption an approximate formula for the residual

resistance coefficients _{is introduced 1:363,} which is nonlinear far part of the coefficients. The _{coefficients of this} formula are functions of the _{Froude number} and are obtained _{by regression analysis of} the experimental data for more than 400 hull forms. The _{calculations show that even the} local hull form changes _{are well}

accounted for in the range of the _{experimental results.} The effect of the bulbous bow is determined separately, _{also by processing of empirical} data.

To predict the _{characteristics of the} viscous flow around the ship hull calculation methods of integral arid _{differential type}

have been developed at BSHC _{:32, 373.}

In the development of _preliminary recommendations for improvement _{of the}

ship hull form _{different empirical criteria have} been employed for Optimization _{of some}

ship geometrical _{particulars obtained as a result} of the experience gained _{and the experimental} investigations _{carried out by BSHC and other} research organizations abroad.

Due to the limited frames of _{the paper} only a brief _{notice can be made of the} investigations related to the development of the _{methods for numerical optimization}

1:39],

etc. _{for improvement of the}

hull form and minimization of the _{resistance, the} development of numerical methods in the solving uf the _{problems connected with the} ship motion in shallow water conditions 1:40,

41, 42], etc.

For _{propeller model}

design and manufacturing a number of approaches and software products have _{been developed,} including from velocity field predictions up to propeller model production.

The design of conventional _{propellers is} performed by the system PROPSVS on the basis of the lifting line and lifting surface theories by means of correction _{factors 1:47].}

Approaches and systems have been developed, as f ollowet

- for high-skew propellers _1:48];

- for _{realization of the}

unsteady lifting

surface method (49];

- for preliminary _propeller

design on the basis of the polynomial _{multiple regression} analysis of _{systematical model}

tests carried out at BSHC 1:50];

- for design of ducted propellers

1:51, 52); - for design _{of counter-rotating propellers}

(53], etc.

In the last 3-4 _{years at BSHC}

intensive investigations have been going on with regard to the development and expansion of the application of _{approaches to the automated} design of _{conventional and}

noncoriventional propulsors 1:81, _{82, 83, 86, 90, 91, 92, 93]}

for improvement of the developed propeller design methods (70, _{71, 72], including for}

high-speed crafts 1:54], etc.

The block-scheme _{on Fig.9}

illustrates the ship _propulsion

CAD/CAM subsystem developed by BSHC, _{while Fig.10 shows}

the block-diagram _{for optimization of the}

design solution, for cavitating propellers applying the data base and _{the software created at} BSHCC1O4] (105].

The _{computational methods}

have been widely used at _{BSHC also in evaluation}

and optimization of the seakeeping _qualities

of ships or _{other floating structures}

(56, 57, 58, 59] and other later

publications 1:73, 74, 75, 76, 77, 78, 79]. _{The reference functions} of the specialized software for _improvement of the ship _{seakeeping characteristics are} shown on Fig.11, while Fig._{12 illustrates the} complex approach employed in _{the a.ialysis and} optimization of the design _{characteristics of}

hip and _{other floating structures in} wave conditions t 106].

As has been already noted in the beginning of this paper the role of the computerization in the _{manoeuvring model} tests at BSHC is also quite _{significant. A} closed cycle system has _{been developed}

for investigation of the _{mano.uvring qualities} with computer application _{in the analysis and} performance _{of model tests Cf ree-running and} with P1*1) in deep and _{shallow water (12,}

13, 15, _{18, 22, 60, 61, 62, 63,}

64]. .2. Deveooment of Scientific

Instrumentation

The _{achievements and}

results in BSHC development would net have been _possible without the efforts _{and activities of BSHC}

for furthering of the experimental methods and technique. Information for different devices, systems and subsystems is presented in a number of BSHC publications [4, 5, 12, 13). Practically at all sessions of BSHC Scientific and Methodological Seminar the aspects of the Centre activity on the development of the experimental technique have been also constantly reflected [15, 16, 17, lB, 119, 20, 21, 22, 23, 24, 25). Beneralized information, descriptions and data are presented in a number of publications too (6, 7, 10, 26, 27). This paper gives generalized quantitative data about the experimental technique created by

BSHC according to Table 4.

Table 4. Major Non-standard Experimental Facilities, Systems and Devices Designed, Constructed and Adopted

at BSHC in the Period of 1971-86 1. Towing carriages 10 6 wavemakers and other large fac i li t i es 2. Experimental 12 il 6 29 facilities eaurirç sys- 20 9 4 33 tems and devices

Dynamometers, 14 12 4 30 transducers, etc. Electronic 24 16 15 55 devices and elements 6. Stands and 28 8 appliances TOTAL: Number

No. Type of 1971- 1981- 1986- Total Experimental 1981 1986 1991

Facility

7 43

108 62 38 208

BSHC policy for development of experimental technique has proved to be expedient in the future as well, having in mind at least the following four

The complex and rapid development of

18 BSHC in accordance with the achievements of the technological progress and the considerable capacities available, were the basic factors for the execution of contracts for foreign customers.

circumstances:

considerably more economically efficient provision of the activity than the delivery from other companies;

attainment of the necessary adequacy and accuracy of the requirements for the experimental investigations;

relatively rapid expansion of the range of services and the applicability of the available experimental facilities;

possibilities for application in other organizations, including for export.

Additional requirements towards the activity of BSHC in this field are ensuing from the necessity of modernization and maintenance of the facilities, devices, etc. created more than 15 years ago., for which the technological progress determines new conceptual and practical solutions.

3.3. Execution f Research Projects for Export

In Tab1 1 in the previous section of

the paper some major generalized data about the orders executed for 4oregri partners in the period of 1978-1991 we,e reflected. Perhaps the projects implemented by contracts

with Krylov Ship Research Institute (KSRI) are of greatest importance for BSHC. Appendix i to this paper contains a list of

about 25 research products obtained as a result of the execution of the contracts, which can be of interest to other partners in the near or far future as well.

The research projects implemented under contracts with KSRI can be classified in the following five groups:

(i) systematic resistance;

investigations of ship

development of methods and systems for design of nonconventional propulsore;

different navigation condition.;

(iv) systematic investigations of the dynamic characteristics of ocean facilities and other floating structures;

(y) realization of auto.at.d complex projects for the experimental facilities at KSRI.

Since the publications in this field are limited (3 joint seminars in Leningrad) and parti al aspects on the autosatipn of the facilities have been reflected (99, 99, lOO, further on in this section of the paper in view of more complet. reflection of SSHC activity, the major projects implemented under contracts with KSRI in the last 4-Z years are pointed out, flamelyl

- investigation

of

the cavitation and noise characteristics of active controls of ocean technique facilities;

- improvement of the methods and development of the application software

of

propeller

hydrodynamic and strength calculations;

- systematic tests

of

suries cavitating propellers with complex geometry

of

the

blade contour;

- development of a procedure for hydrodynamic calculation and design of eridianal blade cascades for water jet propellers

of

high-sped crafts and prediction of the performance characteristics;

- towing and propulsive teste of systematic series of transport ship models;

- systematic investigations of the hydrodynamic characteristics of ducted controllable-pitch propellers for ships with multi-purpose service regimes;

- systematic model investigations of the shallow water effect on the characteristics of the velocity 4ield nonusiiformity in the proximity of screw propellers;

- investigation of the hydrodynamic characteristics of propellers crossing the free water surface and operating in shallow water;

- investigation of the hull flare effect on the characteristics of the longitudinal ship motions;

- investigation of the shallow water effect on the steerability of large-tonnage ships

by PIP3 model test method;

- investigation of the drift excitation forces of floating drilling rigs in waves;

- systematic experimental investigations of the stabilizing moment

of

passive stabilizing tanks of different types with the ai. of improving the motions' calculations of ships equipped with tanks;

- evaluation of systematized hydrodynamic characteristics

of

connected ships in different regimes of joint motions in waves;

- development and delivery

of

software and a technical complex on the basis of .ini-computers IZOT IOZZC and colour graphic working stations 1201 1040C oriented to the solving of the hydrodynaaiic problems and processi ng of complex geometri cal i nf ormati on.

Considerable preparation work has been realized with KSRI with regard to other investigations in the future after 1991, still more significant in terms of scope and amount than those that have been carried out, but they remained without possibilities for practical development in the conditions of the present economic crisis having seized both countries. In this regard considerable BSHC capacities have been disengaged either for utilization by other customers or for essential change of the topics and activities to be covered.

3.4. Same Data about Imorovement of the Indices of Shia Prolects Investiaated by SSHC

In the creation by BSHC of the infrastructure for investigation, development and design, as well as in the implementation of the h programme the economic considerations have had a determining importance.

From the preconditions described in the previous sections of the paper it becomes clear, that there are great possibilities available for application of complex approaches and for utilization of a salid scientific and technological potential for optimization of the hydrodynamic characteristics of ships and other floating structures by reduction of the power required .nd the fuel consumption in operation.

BSHC practice of not perf arcing code! tests simply according to designers' assignment but of recommending efficient technological solutions has become typical in the execution of a number of orders placed by Bulgarian and foreign companies, examples of which concerning improved design projects by means of total or local optimisation of the ship hull forms and resistance reduction are contained in Table 5.

Jable 5. Resistance Reduction in Percentage for Different Design Projects

Investigated by BSHC

carri er

Resi stance Reduction (%) in Ship Motion

By improving the propeller hull interaction favourable changes have been achieved, related to the increase of the coefficient of efficiency. Concerning ships in service, with consideration of the newly acquired knowledge in the propeller design,

increas, of the ship speed with the sam. hull and nain engine power has been realized. Some examples of improvement of old design projects are contained in Table 6.

Significant techno-economic advantages are obtained in variant investigations for choice of the hull forms and dimensions and the propeller complex. An example of the results of such optimization investigations (applying nonconventionul approaches both for the hull form, as well as for the propeller) is a mid-tonnage bulk carrier for which comparative data for different variants are shown on Fig. 13.

11

Table 6. Improvement of Design Projects on the Basis of Complex Investigations Performed at BSHC

4. DEVELOPMENT 0F INTERNATIONAL COOPERATION

As has been pointed out in the beginning of the present paper the role of the international ccop.ration was decisive at all stages of the establishment and development of BSHC. Here some sum total data and information can be given regarding the consultant expert assistance, the staff training, the participation in ITTC and BSHC scientific and methodological seminar.

4.1. Consultant Assistance and Staf 4 Traini na

Expert consultant and technical international assistance have been used episodically still at the stage of the preliminary studies for the choice of a laboratory-experimental complex. The expert assistance acquired a systematical character after 1970 for which data are given in Table 7 t73, reflecting the fí.lds of the technical assi stance rendered, as well as generalized data for the period till the end of 1986.

Especially decisive was the role of th expert meeting in February/March 1972 for the choice of the conceptual solution of BSHC laboratory-experimental campi ex. This meeting was attended Prof.Van Lammeren (NSMB, Wageningen), Prof .Schuster (West Berlin), Dr.Karl Remmers (Hamburg), Prof.Lap (The Netherlands), Dr.Edstrand (Ioteborg, Sweden),

Dr.M.Rakamaric (Zagreb, Yugoslavia). Prof .G.Firsov, Dr. Yu.Pristemi khin and No. Type of Ship

Full Load Ballast

1. 6000 DUT Tanker 3% 6%

2. 19000 DUT Coal-ore carrier

8% 16%

3. 25000 DUT Bulk carrier 2% 8%

4. 29000 DUT Tanker 8%

-5. 63000 DUT Bulk carrier 11V. 17%

6. 80000 DUT Tanker 13% -7. Centainership for 7% 97. 400 containers 8. 65000 DUT Product carri er 8% 14%

9. 15000 DUT Dry cargo 10% 3%

Types of Ships Old Old

No. and Main Engine Project Project

Power (kn) (kn)

1 100 000 DUT Tanker 16.5 17.3

20,870 h.p.

38 000 DUT Bulk 15.6 16.2

carrier, 19,370 h.p.

800 DUT Dry cargo 8.5 10.1

carrier, 530 h.p.

Hydrofoil ship of 33.0 35.0

Dr.A.Gorshkov (Krylov Ship Research Institute, Leningrad) and Mr.W.Crago (UK>

Table 7. International Expert Assistance during the P.riod 1970-1986

No. Field of Technical Experts Duration Assistance Rendered (number) (man/month)

Desigf n and construc- 28 tion of BSHC

Non-standard experi- 48 38 mental technique

Automation and corn- 54 38 puter application

Adoption of theoreti- 85 47 cal and experiintal

methods and technolo-gies in model manufac-ture

Part of the meetings with the international experts in the period of 1981-1986 was ever more often acquiring business-like character in connection with the implementation of joint research projects or contract investigations.

In the period after 1986 and till now the contacts and the interaction with the foreign scientists and specialists continue to be intensive, having mainly business-like character or are connected with their participation in BSHC scientific and methodological seminar.

Summarized data about the training of BSHC personnel in the period of 1969-1986 are shown in Table 8 C7].

Table 8 makes obvious the favourable

possibilities for the development of BSHC personnel during the whole period discussed. In 1981-86 the trips abroad were prevailing in connection with the jointly executed projects and contract investigations. The same business-like character refers also to the trips in the period of 1986-90 when averagely per annum about 100-200 leading specialists of BSHC were realizing missions abroad (some of them executing two and more missions).

Table 8. Major Forms of Personnel Training

107 the Period of 1969-1986

Long-term fellowships in foreign institutions

Study tours and consul-tations

7. Participation in inter-national symposia and conferences

72/320

While till 1991 it was possible to keep up intensive international contacts (including participation of BSHC representatives in the most significant international conferences abroad, at present the economic conditions are very unfavourable due to the drastic rise of the cost of the air tickets in Bulgaria and other financial Lectures and recommen- 85 47 2. Practical exercises and 28/10

dations connected with - lectures (for workers

the research programme and technicians)

and future development

Post-graduate qualif i- 24/12 cation TOTAL: 267 257 Attainment of doctorial 15/540 degrees abroad Participants

No. Form of Training

or Fellowship Durati on

(man/month)

1. Lectures on theoretical 20/90 and experimental ship

hydrodynamics

320/410

problems. The hopes of continuing in the future of a regular exchange of BSHC specialists with foreign institutions are laid on the execution of joint projects under the EC TEMPUS, PHARP, EURICA Programmes, etc. , for which during the current year some preparatory activities have

been realized.

After 1991 there are no possibilities for cooperation of BSHC with UNDP in the traditional forms (executing projects of the country's national programme) and this fact determines the importance of the new forms of cooperation stated above.

-4.2. ØSHC Participation in the ITTC

Since 1972 three representatives of BSHC started for the first time to participate (as delegates> in the 13th ITTC Conference, after which BSHC participation became regular. Since the 14th ITTC in 1975 BSHC became a member-organization of the ITTC and the Director of BSHC became a member of the Advisory Council since 1981 and till now there are representatives of BSHC in the ITTC Technical Committees. With the exception of the 15th ITTC (as can be seen from Table 9,

reflecting statistical data about BSHC participation in the ITTC) written contributions on the reports of the main Technical Committees and the Panel Discussions have been regularly presented in

BSHC participation has been constantly increasing also in the investigations coordinated by the Technical Committees, so that relevant results have been presented and reflected in the reports of the Committees.

In 1975 during the 14th ITTC in Ottawa

BSHC application to act as an organizer (jointly with Krylov Ship Research Institute> of the 16th ITTC in 1981 was announced and

relevant positive decision was taken. Due to the reduction of the duration of the conference the 16th ITTC was held only in Leningrad. Later BSHC confirmed several times the desire to organize the 21st ITTC in 1996. As is evident from Table 9 the activity of BSHC has increased significantly after 1981. Since then BSHC has hosted one meeting of the [TIC Executive Committee and meetings of three Technical Committees (including the present meeting of the Seakeeping Committee in the frames of HADMAR'91). There are grounds for hopes that BSHC activity in the ITTC will be stimulated by the international society, so that a final decision about the 21st Conference in 1996 BSHC can be taken that BSHC should be the host. In this way a very needed culmination in the celebration of the silver 25th Anniversary of BSHC could be created.

4.3. BSHC Scientific and Methudoloqical Seminar on Ship Hydrodynamics

BSHC international seminar on methods and technique in ship hydrodynamics has been permanently acting during the whole period of BSHC development. Since the organization of the first session in January, 1972 till present 19 sessions have been held practically every year with very few exceptions. Its role for the development of the personnel, for BSHC activity and for the international exchange has been constantly increasing and one can judge about this on the basis of the following data C15v25]:

- The number of the papers from 10-15 for the first 4 sessions (1972-1974) till the 10th session in 1981 was constantly increasing, varying between 30 and 85 in order to stimulate 100-200 for the last 5-6 sessions in the period of 1987-1990.

- The participants being about 40-50 from 3-5 countries in the first 4 sessions, after the 5th session as a rule were more than 100, participants from 12 to 20 countries from among them about 50-70 foreign participants from 12 to 20 countries from the east and the west (for the different sessions) ;

- For the whole period, if the number of the participants from all countries is summed up, it would appear that totally participants from about 50 countries have attended, so that for the sessions after the ITTC Proceedings

Table 9. BSHC Particiption [12, 13, 14]. in the ITTC No. of I TTC Year Venue Number/ parti-cipants Members of Corn-mittees Number f publi-cations XIII 1972 W.Berlin/ 4 3 Hamburg XIV 1975 Ottawa 2 1 1 XV 1978 The Hague 5 1 XVI 1981 Leningrad B 3 3 XVII 1984 Goteborg S 3 11 XVIII 1987 Kobe 2 4 14 XIX 1990 Madrid S 6 le

1986 typical is the participation of specialists also from the developing countr i es;

- After the 5th session publishing of the seminar proceedings was started for international usage (intitially in Russian and English and after the 10th session only in English), so that the volUmes have changed from 2 to 4 in numbers for the different sessions dedicated to one or another general topic varying for each sessi on.

- The number of the papers of BSHC authors from 4-5 far th. first sessions after the 6th session has always been over 20 and the papers of the foreign authors during the last 7-8 sessions hay, varied between 25 and 60 without taking consideration of the Joint papers of 8814C authors and foreign colleagues (on the basis of the investigations performed in cooperation -such Joint papers are between S and 10 for

tI* last sessions), etc.

In parallel with the quantitative changes there is a determining trend related to the improve.ent of the contents and quality both of BSHC papers, as well as the papers of the foreign authors, which explains the interest shown to the Seminar Proceedings, their application, citation and purchase. It should b. wished that a specific international forum, such as BSHC seminar has proved to be till now, should continue to function in future as well in spite of the economic difficulties, which Bulgaria (BSHC, respectively) and the other East-European countries are suffering now. 5. TRENDS OF FUTURE INVESTIGATIONS AND

DEVELOPPIENT

The investigations of 881-IC in the last 4-5 years have prepared the present and future investigations and activities, which most generally can be united in three main

directions, as fallowsi

(i) improvement and f uther development of the methods and approaches for optimization of the hydrodynamic characteristics of

ships

and other floating structures, meeting the increasing requirements for reduction of the energy and material expenses and for increase of the safety and reliability of navigation of ships and other floating structures;

further development of expert systems, simulators and onbo.rd systems and other integrated products for possible market realization in Bulgaria and other countries.

expansion of the scope o-f the

hydrodynamic investigations (in view of the application of the results obtained besides in the marine industry, also in other sectors of the economy) and priority development of the topics related to the problems o-f ecology and environmental protect ion.

In connection with the first direction the f uther development and application, for instance, of laser technique in view of which during the last 3-4 years some positive results have been reached from the viewpoint of the increased possibilities for analysis of the phenomena, as is evident from Figs.l4 and 15C1081.

Besides the further development of the laser technique, as is envisaged in BSHC research programme at present, a number of other problems are also included for intellectualization of the experimental investigations in accord with th. development

o-f the technological progress in this field.

It is planned that the activities related to the improvement of the numerical methods and the further development of the data base should be continued. The multi-year investigations o-f BSHC have allowed the creation of a system (principally illustrated on Fig.16) of a system for multi-factor optimization of the hydrodynamic characteristics, which is applicable both at the initial design stages, as well in the analysis and evaluation o-f model test results for different types of ships, including nonconventional (109].

Th. second direction reflects the trend during the last 4-5 years of creating expert systems integrating th. research products obtained by BSHC in different fields. There are encouraging results in the development o-f a CAD/CAll system illustrated on Fig.17 applicable besides for screw propellers, also for hydraulic machines (109].

Also encouraging are the results of BSHC development during the last 5-6 years of simulators for above water ships (Figs.18 and

19) and for submarines (Fig.20). The necessary conditions are available and

further development of simulator systems is envisaged for delivery to different customers in this country and abroad.

The block-diagrams according to Figs.21 and 23 are given in order to illustrate conceptually the new possibilities for delivery of onboard systems proposed by BSHC in the last 2-3 years on the basis of the own experience and in accordance with the determining modern trends of improving the economy and safety of the ships in service.

Concerning the third direction related to the problems of the ecology and the environmental protection certain preparation work has been carried out during the last 10 years. Complex approaches and a procedure for optimization of the parameters of the coastal facilities for protection against the abrasive action of the coastal wave have been developed (Fig.23).

The further programme in this field envisages expansion of the topics,

investigation of the possibilities for using of ecologically non-polluting sources of energy and technologies, development of regional monitoring, etc. The ceasing of the construction works of the wind tunnel recently due to economic difficulties could be continued if possibilities are provided for its utilization for solving of ecological problems, so that the necessary financing should be ensured.

It is considered that in the implementation of BSHC research programme the international cooperation should continue in the form of joint european projects, etc.

6. ACKNOWLEDGEMENTS

The author would like to remind with appreciations making this 20-year retrospection, about the role of a number of foreign scientists and specialists having assisted generously with their experience, encouraging and stimulating the efforts for the successful creation and development of BSHC. Appreciations should be addressed also te the colleagues from BSHC, having participated with enthusiasm and understanding in the attacking and solving o-f different complex and difficult problems in each o-f the stages of BSHC activity.

Regretfully, it should be noted that the appreciations and the gratitude cannot be specified more particularly due to the practical impossibilities to cover and

7. CONCLUSION

As a result of the 20-year development of BSHC in the period of 1971-1991 a rational multi-purpose laboratory-experimental complex has been established with a wide range o-f the

possible investigations and tests. Complex approaches have been developed on the basis

of the application of theoretical and experimental methods for optimization of the technological solutions in accordance with the increasing requirements. Considerable achievements are typical in the development

of the application of the engineering activity and the scientific experiment, as well as in the creation o-f scientific

instrumentation and experimental technique.

Wide international contacts have been established thanks to the projects for BSHC cooperation with UNDP and some ether forme of bilateral and multi-lateral cooperation, having covered the whole 20-year period, starting from 1971. Among the multitude of forms of cooperation, particularly important was the role of BSHC participation in the ITTC and of the Joint projects executed with leading centres in the field of ship hydrodynamics. All this has allowed the attainment of high professionalism by BSHC personnel.

In practical aspect it is necessary to note the systematically increased amount of investigations, model tests and consultant services realized for execution of contracts with Bulgarian and foreign customers.

The economic problems o-f the national economy during the last 2-3 years reflect on the future development. It is necessary that ways of expanding the scope of the hydrodynamic investigations should be found in view o-f their application in the different sectors (besides the marine industry) and a priority role should be attributed to the ecological investigations and problems.

The confirmation of the ITTC community that BSHC could be the host of the 21st ITTC in 1996, would be one of the most important factors for maintaining the international Cooperation and a culmination point in the celebration of the 25th silver Anniversary of the Centre.

enumarate so many persons from abroad and Bulgaria with real and significant contributions in BSHC present development.

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Kovachev Sv., Yovev Y., Computer-Aided Synthesis of Ship Form, PRADS'83, Tokyo and Seoul.

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Lazarov G., Sruseva M., Potential Flow About Ship Hull in Shallow Water, SMSSH'BI, BSHC, Varna, Vol.11.

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Chikolov P., Influence of the Wave Profile Position on the Wave-Pattern Resistance Determined by the Longitudinal Cut Method in Shallow Water, SMSSH'BS, Varna, 1985.

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Varsamov K.. Haimov A., Hadjimikhalev V.. Ship Propeller Design Procedure Based on effective Velocity Field Prediction Method, 3rd Int.Congress on Marine Technology, Athens, 1984, Vol.1. p.69.

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Haimov A., Gerchev S., Calculation of Periodic Loading on a Propeller in Non-Uniform Flow, Jubile. Scientific Session of BSHC, Vol.3, Varna, November 1981.

Yossifov K., Ziatev Z., Stan.'a A..,

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Varsamov K., Haimov A., Minchev D., The Use of Variable Load Actuator Disk in the Design of Ducted Propellers, HYDROTURBO'85, Olomouc 1985.

Haimov A., Minchev D., An Improvement of the Numerical Duct.d Propeller Design, Proc. IVth IMAEM Congress, Vol.5, BSHC,

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Hadjimikhalv V., Kovach.v R., Design Approach and Experimental Investigation of Contra-Rotating Propellers, Proc. of the 6th LIPS Prop.11r Symposium, Veidhoven, 1986.

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SB. Spassov S., On the Mathematical Modelling of Marine Structures' Dynamics and Some Aspects of Its Application, IVth IMAEM Congress, BSHC, Yama, 1987.

Radev D., A Solution to the 2-D Problem of a Body Penetrating into Compressible Fluid, Proc.IVth INAEM Congress, BSHC, Varna, 1987.

Milanov E., Radev D., Experimental Automated Investigation of Ship Manosuvring Qualities by Means of a Free-Running Model, SMSSH'Bl, Vol.11, yama, 1981.

Mil&nov E., Transverse Loading on a Vertical Thin Plate Harmonically Oscillating in the Free Surface Plane of the Fluid, IV National Congress on Theoretical and Applied Mechanics, yama, 1981 (in Russian).

Milìnov E., Haimov A., Numerical Method of Ship Curvilinear Motion Parameter Calculation, Theoretical and Applied Mechanics, Year XI, No.34, Sofia, 1980.

Ililanov E., Lefterova M., Stanev Tz., Preliminary Estimation of Sam. Ship Manoeuvring Characteristics on the Basis of Systematic Model Tests, SMSSH'83, Vol.111, yama, 1983.

Milanov E., Stanev Tz., Model Nano.uvring Investigations with Sinusoidal

Ruddr

Steering, Int.Symposium on Ship Techniques, Rostock, Germany, 1984.

Bogdanov P., Yovev Y., Lazarov S., Ziatev P., Chikolov P., BSHC Computer-Aided System for Ship Form Design Flow Analysis Modules, PRADS'89, Varna, Vol.3.

Aridonov K., Dimitrov A., Ivanov N., Stoeva M., Automated Processing of Screw Propeller Models by a Machining Centre MCO32, SMSSH'84, Varna, 1984.

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Optimization Using Systematic Test Results, Proce.dings of the 10th BMSSH, Vol.1, BSHC, Yarns, NOvember 1981.

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1979 (in Russian).

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Kishev R., Ivanov N., Pomeranetz L., On the Practical Evaluation of Hydrodynamic Coefficients of Semisubmersible Platforms Based on Systematic Model Tests, 4th BOSS Conf srencer Deif t, 1985.

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Radev

_D.,

Kishev R., Stephanov A., Stanev Tz., Experimental Investigation of the Ship Seakeeping Qualities by an Automated System, S.!., yama, 1982.

Radev

D.,

Milanov E., Stephanov A., Spassov S., On the Software Development of Planar Motion Mechanism Tests at BBHC, SMSSH' 82.

Radev

D.,

Stephanov A., Software for Automated Experimental Investigation of the Seakeeping and Manosuvring Qualities of Ships and Offshore Structure Models, SMSSH' 83.

Radev D., Stephanov A., Development and Realization of a Method for Real Time Data Acquisition of Slamming Pressure Signals, SMSSH' 86.

Ziatev Z., An Algorithm and a Computer Program for Multiple Linear regression Analysis, SMSSH'Bl.

Ivìnov N., Kalchev R., Automated System for Data Acquisition and processing from Screw Propeller Model Tests in a Cavitation Tunnel, 3rd National Conference on Organization and Automation of Experimental Investigations, Rousse,

1981 (in Bulgarian).

Kalchev R., Ivanov N., Dimitrov V., Software Package for Processing of Results from Systematic Cavitation Tests on Screw Propellers, SPISSH'Bl, yama, Bulgaria.

YossifDv K., Lyutov N., Ziatev Z., Ivanov N., Automated System for data Acquisition, On-Line Processing and Presentation of Results from Systematic Model Tests of Ship Screw Series in Upen Water, SMSSH'81, Varna, Bulgaria (in Russian).

Ivanov N., Automated System for Propeller Unsteady Thrust an Torque Measurements in Towing Tanks, SMSSH'Bl, yama, Bulgaria.

Brusseva M., Bonev R., Stoyanov S., Mileva I., Two Methods for Spectrum Density EstimatiDn by Means of Weight Functions, Proceedings of BSHC Jubilee Scientific Session, Vol.3, BSI-4C, Yama, 1981.

Bonev R., Application of

Spline-Regression Analysis and D-Optimum Experiment Planning in a Cavitation

Tunnel, SMSSH'84, yama, Bulgaria.

Bonev R., Stoyanov S., Application Program Package for Statistical Analysis of Random Values and Processes, SMSSH'84, Varna, Bulgaria.

Ivanov N., Automation of the Experiments in BSHC Cavitation Tunnel - Present State and Perspectives, SMSSH'84, Yama,

Bulgaria.

Lyutov N., Program Packages for Automated Performance of Calm Water Tests in the Deep Water Towing Tank of ESHC - Present State and Perspectives, SMSSH'84, Varna,

Bulgaria.

Mueva

I., Stoyanov S., Application Program Package for Development and Manipulation of the Data Base for the Results of Screw Propeller Model Tests in BSHC Cavitation Tunnel, SMSSH'84, Varna,

Bulgaria.

Mueva I.., Stoyanov S., On the Approach to Organizing an Information Data Base for the Results of Ship Model Experimental Investigation in a Deep Water Tank, SMSSH'84, Yama, Bulgaria.