Identification of Flapper Fin Oscillations for Active Flow Control Applications in Improved Watercraft Propulsion

摘要

In this study, the data analysis of an oscillating flapping wing is conducted for the development of a describing function model especially for heave force data series obtained using a Boundary Element Method (BEM) for different geometrical kinds of flapping wings. The wing experiences a combination of vertical and angular oscillatory motion, while travelling at constant forward speed. The vertical motion is induced by the random motion of the ship in waves, essentially due to ship heave and pitch, while the wing pitching motion is selected as a proper function of wing vertical motion and it is imposed by an external mechanism. The data series obtained by simulation of the unsteady lifting flow around the system was applied to develop a closed-form lumped phenomenological model for fin motion control synthesis. Using this model a state-space controller for thrust augmentation flappers will be later developed. Our study concerning post-processing data series of thrust-producing flapping foils can in effect be a useful application for feedback control law design.