Mode transition in fluid–structure interaction of piezoelectric membrane wings

Flow-induced vibrations can be utilized to harvest energy for micro-air vehicles (MAVs). A flexible membrane wing with an embedded piezoelectric energy harvester at an angle of attack of 12° and the Reynolds number (Re) of 8000 is studied by numerical simulations. An aero-electro-mechanical model is established to investigate the effect of the leading-edge (LE) and trailing-edge (TE) geometries on the fluid–structure interaction (FSI) modes, aerodynamic performance, and energy harvesting performance. A new correction method of structural frequency is proposed that it considers both the aerodynamic stiffness effect and the added mass effect corresponding to a specific FSI mode of interest. The results suggest that the mode transition accompanied by the performance changes is essentially caused by the FSI state transition, which is distinguished by the corrected structural frequency and the vortex shedding one. With the Fourier mode decomposition (FMD) method, the modes of membrane vibration and pressure fluctuation become clear. The LE geometry is found to affect the FSI state by influencing the leading-edge vortices, which further triggers the mode transition.