Pendulum—driven flapping wind energy harvester for environmental monitoring

Abstract This study investigates a novel pendulum-driven flapping wind energy harvester utilizing a pendulum-based mechanism integrated with a piezoelectric cantilever beam, aiming to harness and convert wind energy into electrical power. The energy harvester comprises a square flat plate functioning as a pendulum, which is pivoted to the free end of a cantilever beam. When subjected to wind flow, the pendulum oscillates in the wind direction, inducing coupled motion between the beam and the pendulum. This interaction produces a nonlinear dynamic response, due to the combined effects of structural coupling and fluid-structure interaction. An electromechanical theoretical model has been developed to explore the dynamic response of the harvester. Experimental results demonstrate that the harvester’s performance at a cut-in speed of 5.2 m s −1 and above aligns well with the model predictions. Unlike traditional bluff body-based wind harvesters, this novel design aligns the pendulum motion with the wind direction to enhance vibration intensity and energy transfer through stronger beam coupling. As the wind speed increases, the flapping motion of the pendulum amplifies, triggering large deflections of the piezoelectric beam and resulting in high voltage output. This simple and cost-effective energy harvester generates a maximum peak-to-peak voltage of 45.1 Vpp and peak power of 1.23 mW at a maximum speed of 12.5 m s −1 with optimum load resistance of 220 KΩ.