Pitch Reduction of Ships by Means of Actuated Flaps Operating in the Wake of a Ducted Propeller

摘要

The feasibility of reducing the pitching motions of a ship by actuating flaps mounted in the wake of a ducted propeller was investigated by means of model tests. The results of the study are presented and the pitch reduction attainable in State 5 and 6 seas is discussed. It is indicated that with a flap system of acceptable size installed, the pitch reduction achieved does not justify the added design complexities. Evaluations are made of the effect of the flaps on heave, of the force required to drive the flaps, and of the lift produced. Data obtained from sinusoidal excitation of the model (either by waves or flap oscillation) are presented in graphs, and records containing random signals (from irregular wave tests) were analyzed statistically and the results presented in tabular form. (Author)