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EN
The influence of the curvilinear movement of the ship on the operation of the propeller was studied. It is shown that even at small values of the drift angle and the angular velocity of the vessel, the transverse component of the force on the propeller and the moment are non-zero and cannot be neglected. The existing and proposed new effective mathematical models of the longitudinal and transverse components of force and moment caused by the operation of the ship's propeller are analyzed. Simple expressions for the coefficients of the propeller thrust and the moment on the propeller shaft, the wake fraction, the thrust-deduction factor, and the flow straightening factor on the propeller at any drift angles and angular velocity are obtained. Numerical analysis of the obtained dimensionless components of forces and moments caused by the operation of the propeller is carried out, and their adequacy is shown. It is shown how the specified parameters change for all possible values of the drift angle and angular velocity. For a few commercial vessels of various types, technical characteristics and calculated dynamic parameters are given for the construction of mathematical models of propeller operation during curvilinear movement of the vessel.
PL
W referacie przedstawiono problemy rozdziału wektora sterującego między dostępne pędniki układu napędowego i pozycjonowania przy spełnieniu określonych ograniczeń. Konieczne jest spełnienie warunku minimalnej sumarycznej mocy wymaganej z pędników, co pozwala na uzyskanie minimum zużycia paliwa. Analiza komplikuje się ze zwiększeniem liczby pędników w układzie pozycjonowania, ich rozmieszczeniem oraz dostępnością. Odpowiednie oprogramowanie systemów sterowania umożliwia uzyskanie wymaganej dokładności pozycjonowania lub utrzymania kursu, co jest warunkiem podstawowym na statkach specjalistycznych z systemami dynamicznego pozycjonowania klasy 2 i 3.
EN
Paper discussed the problems of steering vector allocation to thrusters in ship's dynamic positioning systems to the demanded quality of station keeping taking into account the required limitations. The main challenge is minimum of delivered power that allows to get the minimum of total fuel consumption. The analysis is complicated due to increasing the number of thrusters, their allocation and accessibility. The software of dynamic positioning systems ought to allow the keeping of required position or heading what is a basic condition for DPS class 2 and 3.
PL
Przedstawiono wyniki badań mikrostruktury oraz właściwości mechanicznych odlewów piaskowych z brązu BA1055 stosowanego do wyrobu pędników okrętowych. Stwierdzono, że nawet niewielkie zmiany w składzie chemicznym mogą znacząco wpływać na zmiany mikrostruktury oraz właściwości mechanicznych stopu. Wykazano, iż optymalne właściwości mechaniczne uzyskują odlewy, w których stosunek ilości pierwiastków stopowych żelaza do niklu wynosi około 1,0.
EN
The effect of microstructure of BA1055 bronze used for marine propellers sand castings on its mechanical properties has been investigated. It was shown that even small changes in chemical composition can significantly alter microstructure and mechanical properties of BA1055 alloy. The best mechanical properties were obtained for the melts where alloying elements ratio Fe/Ni is about 1.0.
EN
The computer system for the complete design of the tandem co-rotating propellers, presented in this article, has several common blocks and procedures with the computer system for the design of conventional single propellers, presented in detail in Polish Maritime Research No. 1 Vol. 16 (2009). In this article only these blocks and procedures are described, which are different in both systems. The comparative analysis of the designed tandem propeller and a conventional propeller is also included.
EN
The computer system for the complete design of the contra-rotating propellers presented in this article has several common blocks and procedures with the systems for design of single propellers and tandem corotating propellers, presented in detail in the Polish Maritime Research No.1 and No.4 of the Volume 16, 2009. In this article only the blocks and procedures developed specially for the contra-rotating propellers are described. The system is based on the lifting line and lifting surface models and on the Computational Fluid Mechanics methods. The comparative analysis of the contra-rotating propellers and the tandem corotating propellers is included.
PL
W artykule przedstawiono wyniki badań podstawowych właściwości mechanicznych i korozyjnych nowego materiału konstrukcyjnego przeznaczonego na wysokowytrzymałe pędniki okrętowe. Badany materiał wytworzono na bazie niklu z dodatkiem chromu modyfikowanego azotem i pierwiastkami tworzącymi azotki (stop CrNiN). Właściwości nowego stopu CrNiN, który ubiega się o wykorzystanie w budownictwie okrętowym, porównano z właściwościami stopów miedzi obecnie stosowanymi na śruby okrętowe. Najnowszy stop CrNiN wykazał najlepsze właściwości mechaniczne i bardzo dobrą odporność na korozję wśród brązów stosowanych na śruby, co kwalifikuje ten materiał do dalszych badań celem wdrożenia w budownictwie okrętowym w szerokim zakresie, nie tylko na pędniki, ale także na inne wysoko obciążone elementy.
EN
The paper presents the results of fundamental research into mechanical and corrosive properties of new construction material designed for high-resistance maritime propellers. The material investigated was developed on the basis of nickel with addition of chromium modified with nitrogen and elements making nitrides (alloy CrNiN). The properties of the new alloy CrNiN, which is intended to use in shipbuilding, was compared with properties of copper alloys currently used to make ship propellers. The latest alloy CrNiN offered the best mechanical properties and a very good resistance to corrosion among bronzes used to make propellers, which qualifies the material for further investigations in order to implement in a wide extent, not only to make propellers but also other highly-loaded parts.
EN
The computer system presented in this article is composed of several program blocks for the complete design of ship propellers. The design calculations are based on a combination of the modified lifting line theory and on the vortex lifting surface theory. The system enables solution of the following design problems: - calculation of the scale effect on the ship wake velocity field, including the influence of the propeller and rudder on this field at the propeller location - maximization of the propulsive efficiency - optimization of the propeller blade geometry on the basis of the compromise between the cavitation and blade strength requirements - optimization of the number of propeller blades and blade geometry on the basis of the acceptable level of induced pressure pulses and unsteady shaft bearing forces - calculation of the blade spindle torque for the controllable pitch propellers. The computer system is equipped with many numerical options for graphical visualization of the input data, including an easy possibility of their correction and control of the intermediate and final results of calculations.
EN
The computer system for the completed design of the ducted ship propellers has some common blocks and procedures with the analogical system for open propellers that has already been presented in detail in the Polish Maritime Research [1]. This article describes only these blocks and procedures which are specific for the design of ducted propellers. These new blocks concern first of all the procedures for the design calculation of ducted propellers and for the analysis of the ducted propeller operation in the non-uniform velocity field behind the ship hull. The comparative analysis of computation results for different types of ducts is also presented.
9
Content available remote A computer system for the complete design of ship propellers
EN
The integrated computer system presented in this paper is capable of conducting the complete design calculations of ship propellers, including their ana1ysis in the conditions of a real inflow velocity field behind the ship hull.The system enables solution of the following tasks: - calculation of the scale effect on the velocity field in the area of propeller operation, - correction of this velocity field due to the presence of the rudder, - maximization of the propeller efficiency, - optimization of the propeller blade geometry on the basis of the cavitation and strength requirements, ź optimization of the propeller number of blades and of the blade geometry on the basis of the level or induced pressure pulses and unsteady bearing forces. The computer system contains numerous options for visualization or the input data and the results of calculations.
PL
Zintegrowany system komputerowy przedstawiony w referacie pozwala na przeprowadzenie kompleksowych obliczeń projektowych śrub okrętowych połączonych z analizą ich pracy w rzeczywistym polu prędkości za kadłubem statku. System umożliwia rozwiązanie następujących zadań: . określenie wpływu efektu skali na pole prędkości w miejscu pracy śruby, . skorygowanie tego pola ze względu na wpływ steru, . maksymalizację sprawności śruby, . optymalizację geometrii skrzydła śruby na podstawie wymagań kawitacyjnych i wytrzymałościowych, . optymalizację liczby skrzydeł śruby i ich geometrii na podstawie poziomu indukowanych pulsacji ciśnienia i zmiennych sił łożyskowych. Opisany system komputerowy posiada wiele możliwości wizualizacji danych wejściowych i wyników obliczeń.
EN
This paper concerns an algorithmic method for preliminary selection of parameters of ship propulsion system fitted with fixed screw propeller in the case when the ship’s operation is associated with significant changes of waterway depth and width, hull resistance of the ship and its service speed. Mathematical model arguments of the considered design problem are main ship design parameters identified in the preliminary design stage. Structure of the formulated model complies with formal requirements for continuous- discrete mathematical optimization problems. The presented examples of application of the method concern an inland waterways ship fitted with compromise screw propeller optimized in the sense of minimization of fuel consumption for passing a given route distance within a given time. The elaborated method may be especially useful in designing such ships as : coasters, inland waterways ships, tugs, pushers, trawlers, mine sweepers, icebreakers etc.
11
Content available remote Hydroacoustic activity of the ship propeller operation
EN
The paper presents ship propellers as the source of a variable pressure field in water. The frequency spectrum of this field covers the entire audible range and beyond this range. This pressure field is generated by several physical mechanisms: the rotating hydrodynamic loading of the blades, the displacement effect of the rotating blades, the boundary layer effect, and, first of all, various forms of cavitation. The relative importance of these mechanisms is analysed and the methods of the theoretical prediction of the propeller generated variable pressure field are briefly presented. The results of the prediction are compared with experimental data.
PL
Przedstawiono problem wyznaczania właściwości mechanicznych w sekcji odlewu śruby napędowej, która ma być naprawiana (prostowanie lub spawanie skrzydła śruby). Kilkadziesiąt wyników badań zależności grubości śruby W i właściwości mechanicznych odlewu WM, podanych w literaturze (1,2) opracowano statystycznie i wykazano, że najlepiej tę zależność oddaje krzywa regresji opisana równaniem logarytmicznym o postaci WM=a+blgW.
EN
The paper presents the problem of determining mechanical properties in the part of propeller which is to be repaired (levelling or welding a blade of propeller). A few tens of results of studies on dependence of propeller thickness Wand mechanical properties of cast WM, presented in literature [1,2] were analysed ,statistically ant it was shown that this dependence is best illustrated by a regression curve described with logarithmic equation as follows WM = a + blgW.
EN
This paper concerns a new strength calculation method of ship propellers. Within its scope a propeller modelling technique with the use of a CAD pre-processor (PATRAN), calculation procedure based on Finite Element Method software (NASTRAN)), as well as a way of performing numerical calculations, was developed. Results of example propeller calculations for a tanker are also attached.
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