Bio-inspired wing-like bluff body for wind-induced vibration energy harvesting via piezoelectric-electromagnetic hybrid mechanism

Harvesting wind energy using piezoelectric and electromagnetic transduction has attracted increasing attention to implement the autonomous self-sustaining electronics over the past two decades. To offer an alternative solution for the poor robustness of typical galloping-based energy harvesters at unexpectedly high wind speed, a bio-inspired wing-like bluff body for wind-induced vibration energy harvesting via a piezoelectric-electromagnetic hybrid mechanism is proposed in this paper. The most attractive feature of the energy harvester was the adaptive shape-transforming ability of the wing-like bluff body, where the shape of wing-like bluff body could adaptively adjust with various wind speeds. Accordingly, the vibration mode of energy harvester shifted from galloping to vortex-induced vibration. Therefore, the energy harvester could yield a large electric output at low wind speed as well as possess high robustness at high wind speed and considerable power generation capability. A series of simulations and experiments have been conducted to verify the feasibility of the proposed structure and principle. The results demonstrated that width ratio and tip thickness of the wing-like bluff body brought a significant effect on the power generation capability of the energy harvester. The piezoelectric unit and electromagnetic unit achieved a maximum output power of 1.41 and 6.24 mW at a wind speed of 10 m/s with the optimal load resistances of 400 and 1.5 kΩ, respectively. Furthermore, the utilization of piezoelectric unit and electromagnetic unit enables the illumination of 86 and 250 light-emitting diodes, respectively.