Studies have shown that 'ring-wing' or 'ducted' tip devices reduce substantially the inception index of trailing vortices generated by a hydrofoil (Green et al. 1988). It has also been shown that these devices improve the lift/drag ratio of an airfoil at high angles of incidence (Duan et al. 1992). These findings indicate that there may be a marine application for the ducted tip. Experimental equipment has been designed and manufactured in preparation for upcoming tests of a propeller with ducted tips. The tips are tubes aligned with the propeller blade tips that will replace a radial fraction of the original blade tips equal to the diameter of the tubes. The tube dimensions have been chosen according to the span/tip diameter and chord/tip length ratios used by Duan et al. (1992), and the tubes will be given a curvature equal to the propeller tip radius. Field trials will be conducted on a 36 inch diameter propeller that is used to propel a 45 ft. fishing (seine) boat operating in the coastal waters outside Vancouver. The performance of the propeller will be measured in terms of the propeller efficiency as a function of advance ratio. A special force transducer has been designed that is capable of recording both torque and thrust on the propeller shaft even though these are expected to produce shaft strains of different orders of magnitude. As a supplementary means of monitoring the propeller performance, a hydrophone will be located near the propeller wake in order to measure the tip vortex cavitation noise.
Sea trials of a ducted tip propeller designed for improved cavitation performance
Versuche auf See mit einem Propeller mit Rohrkanal am Flügelrand zur Verbesserung von Kavitationseigenschaften
1994
8 Seiten, 7 Bilder, 4 Quellen
Conference paper
English
Sea trials of the ducted tip propeller
Tema Archive | 1998
|Ducted Propeller Assault Transport Study Performance
NTIS | 1956
|Ducted Propeller Assault Transport
NTIS | 1956