Design Method and Application of an Asymmetric Stator Upstream of an Inclined Shaft Propeller

stator upstream of a propeller in an inclined flow. Two contrasting applications of this method are presented. The first application is an asymmetric stator and a matched propeller design for a typical surface ship with an inclined shaft propeller. The primary purpose of this design is simply to validate the design method. A new propeller and a large span asymmetric stator are designed which increase propulsive efficiency relative to an existing propeller. Model test results are provided which show that significant flow smoothing is achieved across the entire span of the propeller. The. model tests show that the predicted increase in propulsive efficiency of 6-7% was achieved. The second application is a backfit to a high speed U.S. Coast Guard patrol boat. The purpose of this design is to eliminate severe cavitation erosion near the root of the existing propeller. A small span asymmetric stator is designed to operate with the existing propeller. Details of the design and cavitation predictions are provided. Cavitation erosion tests in the DTMB water tunnel demonstrate that the severe erosion can be eliminated.