Abstract
A complete design of tandem co-rotating propellers using the new computer systemThe 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.
Highlights
The tandem co-rotating propeller consists of two propellers, usually of the same diameter and the same number of blades, mounted on the same shaft with certain angular shift between them
With respect to the design system for conventional single propellers, the system for tandem propellers differs by the following elements: a) the procedures for the graphical presentation of the geometry of both propellers independently, b) the procedures for determination of the design velocity field for both propellers, taking into account their mutual interaction, c) the procedure for modification of the non-uniform velocity field used in the analysis of the propeller operation by the program UNCA, d) the procedures for determination of the pressure pulses induced by both propellers separately and by the entire tandem propeller set, e) the procedures for determination of the shaft bearing forces for both propellers separately and for the entire tandem set
This induced velocity field is superimposed on the non-uniform velocity field generated by the ship hull. Such a modified velocity field enables the analysis of the forward and aft propeller of the tandem set. Both newly designed propellers of the tandem set are analyzed by the program UNCA from the point of view of: a) detection of the different forms of cavitation in a number of selected angular positions of the propeller blades in the non-uniform velocity field, b) calculation of the pressure pulsations induced by each of the propellers separately and by the entire tandem set on the hull surface or in the surrounding space, c) calculation of the fluctuating bearing forces and moments on each of the propellers separately and by the entire tandem set
Summary
The tandem co-rotating propeller consists of two propellers, usually of the same diameter and the same number of blades, mounted on the same shaft with certain angular shift between them (cf. Fig. 1). With respect to the design system for conventional single propellers, the system for tandem propellers differs by the following elements: a) the procedures for the graphical presentation of the geometry of both propellers independently, b) the procedures for determination of the design velocity field for both propellers, taking into account their mutual interaction, c) the procedure for modification of the non-uniform velocity field used in the analysis of the propeller operation by the program UNCA, d) the procedures for determination of the pressure pulses induced by both propellers separately and by the entire tandem propeller set, e) the procedures for determination of the shaft bearing forces for both propellers separately and for the entire tandem set. The basic block diagram (cf. Fig. 2) is supplemented with the block diagram of the program for design of the tandem propellers (cf. Fig. 3) and with the block diagram of the program for analysis of the tandem propeller operation (cf. Fig. 4)
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