Abstract: A rudder operating behind a propeller can experience large onset flow angles along the rudder span. At a given speed, the maximum rudder angle before cavitation is substantially higher in turning to one direction than to the opposite side. At high speeds, rudders can experience severe surface cavitation, even at zero degree rudder deflection angle. Observation from full-scale trials and dry dock inspection of a surface ship combatant show that rudder cavitation is a real problem in terms of ship operation and maintenance. It is shown in this paper that cavitation inception and erosion problems associated with the existing fleet rudders can be avoided or reduced by using the concept of a twisted rudder. A fleet rudder can be twisted along its span to align the incoming flow. The twisted rudder model has been designed, fabricated, and tested in the Navy's Large Cavitation Channel (LCC). Two-component Laser Doppler Velocimetry (LDV) was used to measure the field velocity and inflow angles in the propeller slipstream. A dynamometer and a series of pressure taps were used to measure rudder lift, drag and pressure distributions on the rudder surface. To evaluate the effect of twist angles on rudder performances, a full-scale rudder, designated the non-twisted rudder, has also been fabricated and tested back-to-back in the LCC with the twisted rudder for direct comparison. The advantages of using a twisted rudder to improve cavitation performance are presented in this paper.
Publication Year: 1997
Publication Date: 1997-12-01
Language: en
Type: article
Indexed In: ['crossref']
Access and Citation
Cited By Count: 44
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