Importance

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Abstract

An asymmetric set of pre-swirl vanes (stators) and a specially matched propeller for use on an inclined shaft. The propulsor is designed by considering the mutual interaction of the propeller on the vanes and the vanes on the propeller. The propulsor unit provides the following: 1. increased propulsive efficiency due to the reduced rotational (swirl) and axial kinetic energy losses in the propulsor's slipstream; 2. reduction or elimination of propeller cavitation; 3. reduction or elimination of unsteady propulsor forces as well as propulsor-induced hull vibrations. A unique feature of the present invention is that a prior art flat faced commercially available propeller can be modified to match the vane flow field for optimum propulsor performance. The use of commercially available propellers reduces the installation or hardware cost significantly and allows the propeller to be repaired easily if damaged. Another unique feature is that the vanes operate well with an unmodified commercially available prior art flat faced, optimum constant pitch propeller, and that the propeller as modified for use with the vanes also performs exceptionally well without the vanes. The modified propeller without vanes in fact outperformed the prior art flat faced optimum constant pitch propeller used on the 41 foot test craft.

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First Claim