Micro windmill piezoelectric energy harvester based on vortex-induced vibration in tunnel

A micro windmill piezoelectric energy harvester is proposed to explore the wind energy translation based on vortex-induced vibration(VIV). The novel power takeoff is composed of a wind turbine with three blades, an air blast blower, an ancillary wind tunnel, and a circular PVDF piezoelectric converter. The air blower improves the airflow speed in the wind tunnel. A bluff body is fixed in the flow field to induce vortex and excite the circular PVDF piezoelectric film vibration. Theory and experiments are conducted to investigate the energy translation. Based on the blade element momentum method(BEM), the theoretical model of the air blast blower is derived. The calculation results show that the axial fan blasts the air into the wind tunnel, and the airflow speeds range from 1.37 m/s to 18.78 m/s. Furthermore, the theoretical model of the VIV is developed to decorated the airflow aerodynamic characteristics around the bluff body. The vortex-induced high-frequency resonance consequently improves the piezoelectric energy harvesting efficiency and promotes the excitation force amplitudes. Correspondingly, the output electric power on the piezoelectric plate is numerically investigated based on the theoretical model and experiment. The optimal output power matches the load resistance and the wind velocity on the bluff body. The maximal output power arrived at 8.97 μW on the external load resistance of 650 KΩ with a wind velocity of 19 m/s. Furthermore, experimental results validate the theoretical dynamic model and show that a windmill piezoelectric energy harvester based on vortex-induced vibration (VIV-WPEH) can increase the output power over either range of the low natural airflow speed and the optimizing bluff body individually.