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  • Author: Zbigniew Krzemianowski x
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Investigations of influence of screw propeller operation on water flow around stern part of ship hull

Investigations of influence of screw propeller operation on water flow around stern part of ship hull

This paper presents results of measurements of velocity field in before- the - propeller flow in presence of a ship model hull of two configurations, as well as comparative calculations of velocity field on a full-scale ship. Analysis of the research results showed that input data to Biot-Savart formula should be modified in the case of calculations of propeller-induced velocities on ship hull surface.

Open access
A complete design of contra-rotating propellers using the new computer system

A complete design of contra-rotating propellers using the new computer system

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.

Open access
A complete design of tandem co-rotating propellers using the new computer system

A complete design of tandem co-rotating propellers using the new computer system

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.

Open access
A complete design of ship propellers using the new computer system

A complete design of ship propellers using the new computer system

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.

Open access
A complete design of ducted propellers using the new computer system

A complete design of ducted propellers using the new computer system

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.

Open access