Accession Number : ADD017835

Title :   Rudder for Reduced Cavitation.

Descriptive Note : Patent, Filed 21 Apr 95, patented 10 Oct 95,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Shen, Young T

Report Date : 10 Oct 1995

Pagination or Media Count : 22

Abstract : Snip 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. 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 from the rudder's root to the rudder's tip. Moreover, each individual rudder section may be twisted in the chordwise direction to substantially align the individual sections with the incoming flow along the entire chord from the rudder's leading edge to the rudder's trailing edge. (AN)

Descriptors :   *MARINE RUDDERS, *PATENTS, VELOCITY, PRESSURE GRADIENTS, MATHEMATICAL MODELS, VIBRATION, MATRICES(MATHEMATICS), SHIP MOTION, ANGLE OF ATTACK, EROSION, FLOW FIELDS, STALLING, LEADING EDGES, FLOW NOISE, DRAG, ROTATION, HYDRODYNAMICS, PRESSURE DISTRIBUTION, MARINE PROPELLERS, AXIAL FLOW, TWIST(MOTION), TRAILING EDGES, CAVITATION

Subject Categories : Marine Engineering

Distribution Statement : APPROVED FOR PUBLIC RELEASE