Ships – Steering mechanism – Rudders
Patent
1993-10-13
1995-05-16
Swinehart, Edwin L.
Ships
Steering mechanism
Rudders
B63H 2506
Patent
active
054151228
ABSTRACT:
Ship rudders are subjected to propeller induced velocities and induced flow angles that vary along the rudder span and chord. Because of non-zero onset flow angles, a suction pressure peak is formed at or near the leading edge of the rudder where early cavitation occurs. The present invention is directed to a rudder and method for minimizing early cavitation and related ship vibration and for thus improving acoustic and hydrodynamic performance thereof. The rudder of the present invention is twisted so as to have profiles along its entire span that are aligned with propeller induced non-zero onset flow angles into the rudder plane. The twist of the rudder sections vary in the spanwise direction, that is, the twist angle of one rudder sections may vary relative to the twist angle of adjacent or remaining rudder sections, such that the rudder experiences substantially zero angles of attack along the span.
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Bailer, J. W., S. D. Jessup and Y. T. Shen, "Improvement of Surface Ship Propeller Cavitation Performance Using Advanced Blade Sections," Proceedings of the Twenty-Third American Towing Tank Conference (1993), pp. 185-193.
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Hsin, Ching-Yeh, "Development and Analysis of Panel Methods for Propeller Unsteady Flow," Doctoral disertation, Massachusetts Institute of Technology (1990).
Borda Gary G.
Swinehart Edwin L.
The United States of America as represented by the Secretary of
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