Experimental and numerical study of underwater piezoelectric generator based on Vortex-induced Vibration

Abstract

Efficient energy use to be transformed into electricity for small power devices has drawn increasing attention. A piezoelectric energy harvester is proposed to convert flow energy underwater to electrical energy. The harvester consists of the connecting device, springs, base, bluff body, piezoelectric cantilever beam and displacement sensor. The output voltage is derived from the flow-solid-electric coupling equations, including a nonlinear van der Pol equation, a linear equation of structural vibration and a piezoelectric equivalent circuit. Vibration response and output performance are obtained based on the finite central difference method. The theoretical results show that the vibration frequency, amplitude and average power increase with the limited water velocity. Furthermore, it is demonstrated that a proper selection of structure mass and load resistance can improve average harvested power for the available water velocity. Finally, the experimental prototype is fabricated to test piezoelectric generator performance at different water speeds, which shows good agreement with the theoretical results. This work provides a significant guide for the underwater use of piezoelectric energy harvesters.