Experimental Investigation of Oscillating Foil Propellers

Abstract

A flexible fin propeller model with a rectangular oscillating foil of aspect ratio 4.0 has been tested in the Hydrodynamics Laboratory of the University of Glasgow. The performance of the model was tested in both forward speed zero speed conditions. Experimental results are compared with theoretical results from a linearised mathematical model. High propulsive efficiencies around 0.7 were obtained with this model propeller. In the zero speed condition, the propulsive thrust coefficient (CTb) decreases as the oscillating frequency increases. Investigations were made into the speed of advance variation over span of the foil, and frictional losses in the driving mechanism. The test apparatus was checked to make sure that it functioned as intended in all aspects. The application of a flexible fin propeller to a small ship is found to be feasible from a hydrodynamic viewpoint.