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|9 (HR-ZaNSK)970417041
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|a (HR-ZaNSK)000187308
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|a 629.5.016.8(043.3)
|2 MRF 1998.
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|a Sambolek, Miroslav
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|a Prilog istraživanju utjecaja nejednolikosti polja brzina na krmi broda na djelotvornost vijka i ukupnu ekonomičnost broda :
|b doktorska disertacija /
|c Miroslav Sambolek.
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|a Zagreb :
|b M. Sambolek,
|c 1995
|e ([s. l. :
|f s. n.])
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| 300 |
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|a 115 listova, 78 prilozi :
|b table, graf. prikazi ;
|c 30 cm.
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| 500 |
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|a Doktor tehničkih znanosti - strojarstvo
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| 500 |
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|a Komisija za ocjenu: Alice Vučinić, Antun Gamulin, Ante Bosnić; Komisija za obranu: Alice Vučinić, Antun Gamulin, Ante Bosnić; datum obrane: 27.12.1995.; datum promocije:
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|a Sveučilište u Zagrebu, Fakultet strojarstva i brodogradnje, Zagreb, 1995
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|a Bibliografija: str. p 57 - p 67
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|a Summary
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|a Sažetak: Cilj rada je stjecanje saznanja o utjecaju sustrujanja trenja i potencijalnog sustrujanja na ukupni stupanj korisnosti propulzije. Ta saznanja omogućuju racionalno smještanje vijka na takvo mjesto na krmi broda, gdje će on najbolje iskoristiti primljenu snagu. U uvodu se govori o svrsi i potrebi optimaliziranja brodskih propulzora, pa se to dovodi u svezu s općenitijim problemom optimaliziranja svih hidrodinamičkih svojstava broda. Naglašeno je da je optimaliziranje hidrodinamičkih elemenata broda samo dio sveobuhvatne zadaće koju valja riješiti pri osnivanju trgovačkog broda - postizanje najveće moguće ekonomičnosti. Nadalje se u općenitom apstraktnom obliku formulira zadaća oblikovanja uzajamno prilagođenog brodskog trupa i propulzora.
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|a Pokazano je koji uvjet mora zadovoljiti geometrija trupa i propulzora i zakon gibanja propulzora, da bi se za gibanje broda konstantnom brzinom utrošila najmanja moguća snaga. Budući da je ovako postavljena opća zadaća presložena za praktično rješavanje, to se istraživanje sužuje na analiziranje samoga propulzora i na traženje njegovog najpovoljnijeg mjesta u odnosu na zadani trup. Budući da se u radu razvijaju neki novi hidrodinamičko-matematički modeli propulzora, to je dan sažeti pregled postojećih modela, u kojemu se pokušalo klasificirati pojedine tipove teorija. Pri tome se razlikuju modeli vijka s konačnim i beskonačnim brojem krila. U slijedećem je poglavlju opisan rad vijka pomoću osnovnih pojmova fizike.
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|a Osobito se željelo naglasiti važnost izgubljene snage, pa je razjašnjeno o kojim parametrima ovisi gubitak snage u slučaju rada vijak u jednolikom polju brzina. Posebna je pozornost posvećena temeljnim fizičkim zakonitostima koje upravljaju pojavama u polju sustrujanja. Postupnim razvijanjem modela rada idealnog propulzora u sve složenijim uvjetima, došlo se do izraza koji opisuju odnose efektivnog i nominalnog sustrujanja , i to posebno potencijalne i viskozne komponente, te upijanja, pri čemu se također odvojeno promatra viskozno i potencijalno upijanje. Uveden je pojam utjecaja blizine trupa na stupanj korisnosti propulzora; time se uzima u račun povećano opterećenje vijka i zbog toga smanjeni stupanj korisnosti u odnosu na izolirani propulzor.
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|a Radi usporedbe s dobivenim rezultatima prikazan je i dotjerani oblik ranijeg rada autora, u kojem se na jednostavan način pokušalo dobiti odgovor na pitanje o utjecaju prirode sustrujanja na stupanj korisnosti propulzije, i koji se temelji na relacijama navedenim u literaturi. Analizirana je energija koja je sadržana u polju sustrujanja i zorno su predočeni karakteristični slučajevi pretvorbe energije iz jednog oblika u drugi. Razvijen je novi model idealnog vijka, koji radi u konstantnom polju sustrujanja sastavljenom od viskozne i potencijalne komponente. Model radi s veličinama u tri karakteristična presijeka unutarnje struje vijka, uzima u obzir promjenu tlaka uslijed vrtnje mlaza, a pomoću jednadžbe kontinuiteta napisane u diferencijalnom obliku povezuje polumjere iste strujnice u raznim presijecima.
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|a Analiza ovoga modela je pokazala da se strujanje u ravnini diska može dobiti ne uzimajući u obzir uvjete u beskonačno dalekom presijeku mlaza. U prilozima su razmotrena pitanja koja su općenito važna za hidrodinamiku brodskog vijka i međudjelovanje trupa i propulzora. Razjašnjen je pojam efektivnog poriva propulzora, pojam koji može biti koristan u izgradnji matematičkih modela. Također se govori općenito o modelima nekih pojava, o podjeli modela, uvjetima koje moraju zadovoljiti i njihovoj zadaći, a spomenuta je i jedna alternativna podjela modela. Posebno se spominju modeli sustava i važan model potencijalnog strujanja nestlačive tekućine. Pokušalo se sistematizirati pojmove i razviti cjeloviti sustav označavanja veličina koje se susreću kod sustrujanja, pri čemu se posebno pazi na razliku proračunskog i efektivnog sustrujanja.
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|a U prilogu se govori i o vrtlozima i naglašava njihova kinematička priroda,koja se u hidrodinamici često zaboravlja,pa im se pridaje svojstvo uzroka strujanja,iako su oni samo posebni oblik strujanja kojega su izazvale sile djelujući na tekućinu.U cilju ilustracije načina strogog dokazivanja u hidrodinamici vijka prikazan je izvod teorije Žukovskoga.Također je opisan model međudjelovanja brodskog vijka i trupa koji se temelji na radovima ruske škole brodskih hidrodinamičara.U ovom su radu prikazani neki novi modeli djelovanja brodskih propulzora i njihovog međudjelovanja s brodskim trupom. Na temelju tih modela proračunati su dijagrami prema kojima se može procijeniti utjecaj pojedinih komponenata polja sustrujanja na ukupni stupanj korisnosti propulzije. To predstavlja znanstveni doprinos praktičnom problemu optimalizacije propulzije broda.
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|a (193 stranice, 16 slika, 16 dijagrama, 1 tablica, 95 bibliografskih podataka, original na hrvatskom jeziku). Ključne riječi: brodski vijak, optimalizacija propulzije, međudjelovanje broda i propulzora.
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|a Summary: The aim of this work was to gain knowledge about the influence of friction wake and potential wake on overall propulsion efficiency. This knowledge would enable rational fitting of the propeller at a particular place of the ship stern where it would utilise delivered power in the best possible way. Tn the introduction, the purpose and the need for the optimisation of ship propellers is considered, and it is related to a more general problem of the optimisation of all hydrodynamic properties of a ship. It is pointed out that the optimisation of ship's hydrodynamic parts is only a part of the comprehensive task which is to be done while designing a merchant ship - the obtaining of the highest possible efficiency.Further on, the task of designing a well-matched ship hull and propeller is formulated in a general abstract form.
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|a It is shown which requirement is to be met by the hull and propeller geometry and the law of propeller motion in order to consume the lowest possible power to provide ship motion at constant speed. Since the so formulated general task is too complex for practical solving, the research was narrowed down to the analysing of propeller and searching for its best position with respect to the given hull. Because some new hydrodynamic-mathematical models of propellers were developed in this work, a short review of the existing models is given and an attempt is made to classify individual types of theory. While doing this, the distinction is made between the propeller models with finite and infinite number of blades.In the next chapter the propeller operation is described by means of basic physical concepts.
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|a The intention was to emphasise in particular the importance of lost power, and it is therefore specified which parameters influence the power loss in the case of propeller operation in a uniform wake field. Special attention was paid to basic physical laws which govern the wake field phenomena. By gradual developing of the model of ideal propeller operation in more and more complex conditions, the expressions describing the relationships between effective and nominal wake were obtained. These expressions primarily concern potential and viscous component, and also thrust deduction, where again viscous and potential thrust deduction were separately considered.
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|a The term "influence of hull proximity on propeller efficiency" is introduced, and thus the increased propeller loading is taken into account, and therefore also its decreased efficiency in relation to an isolated propeller is explained. For the purpose of comparison with the obtained results, an earlier work of the author is presented in an improved form. In that work an attempt is made to obtain in a simple manner the answer to the question about the influence of the wake character on overall propulsive efficiency, and it is based on relations from literature. Also, the energy contained in the wake field is analysed, and the characteristic cases of energy transformation from one form into another are illustratively presented. A new model of an ideal propeller was developed.
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|a It operates in the constant wake field composed of viscous and potential component. The model operates with the values in three characteristic sections of the propeller internal flow, takes into account pressure increase due to the rotation in the race, and by means of the equation of continuity written in a differential form connects the radii of the same streamline at different sections. The analysis of this model shows that it is possible to obtain the flow in the propeller plane without taking into consideration the conditions infinitely far in the race. In the supplements, the questions generally important for propeller hydrodynamics and hull-propeller interaction are considered. The explanation is given for the term "effective thrust" which is the term that might prove useful in developing mathematical models.
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|a Also, the models of some phenomena, classification of models, requirements they have to meet, and their functions are generally considered, and one alternative classification of models is mentioned. The models of systems and the model of potential wake of incompressible fluid are mentioned in particular. An attempt was made to systemise the terms and to develop an integral system of denotation of values encountered in wake field, paying attention to the difference between model wake fraction and effective wake field. In the supplement, vortexes are also discussed, and their kinematic nature, often forgotten in hydrodynamics, is pointed out, and thus they are given the attribute of being the cause of wake field, although they are only a special form of flow induced by the forces acting on the fluid.
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|a In order to illustrate the strict way of proving in propeller hydrodynamics,the derivation of the theory of Zhukovsky is given.Furthermore,a description of the hull-propeller interaction model based on the works of ship hydrodynamicists from the Russian school is given too.In this work some new models of ship propeller action are presented,and its interaction with ship hull is described.On the basis of these models diagrams were calculated.By means of these diagrams it is possible to estimate the influence of individual wake field components on overall propulsive efficiency,which represents a scientific contribution to the practical problem of ship propulsion optimisation. Key words:ship propeller,propulsion optimisation, ship-propeller interaction.
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| 650 |
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7 |
|a Brodski propulzori
|v Disertacije
|2 nskps
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| 650 |
|
7 |
|a Brodovi
|x Hidrodinamika
|v Disertacije
|2 nskps
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| 700 |
1 |
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|a Vučinić, Alice
|4 oth
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| 700 |
1 |
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|a Gamulin, Antun
|4 oth
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| 700 |
1 |
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|a Bosnić, Ante,
|c inženjer brodogradnje
|4 oth
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| 981 |
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|p CRO
|r HRB1995
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| 998 |
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|n DCD
|c lbao9802
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| 852 |
4 |
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|j DCD-ZG-109/97
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| 876 |
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|e DCD
|a 109/1997
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| 886 |
0 |
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|2 unimarc
|b 12038iam0 2200481 450
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