Suppression of reflected waves of an aquatic flexible plate to improve efficiency of an aquatic propulsion mechanism

Abstract

This study deals with a generation method of undulatory motion of an aquatic flexible plate, to improve the efficiency of an aquatic propulsion mechanism by suppression of a reflection wave on a trailing edge. Firstly, non-reflection impedance of a flexible plate was derived by using a matrix-based wave approach, and then control forces for trailing edge of a plate was derived by the impedance. Secondly, obtained non-reflection impedance was translated into the relationship of the displacements between leading edge and trailing edge, to generate a pure traveling wave by three linear actuators. By the relationship, appropriate forced displacements of trailing edge are available by referring to driving signals. However, the method uses a wave number of an aquatic planar plate, which is dependent on added mass effect. To overcome this difficulty, an identification method of wave numbers with constant amplitude for various driving frequencies was introduced. Finally the method was applied to an experimental apparatus. Experimental results showed that a quasi-pure traveling wave was generated on an aquatic flexible plate by the method.