Experimental study on underwater fin-shaped piezoelectric energy harvester based on wake galloping

Abstract

This paper presents a novel piezoelectric energy harvester based on wake galloping in water. This harvester consists of a bluff cylinder and a fin connected with a macro fiber composite (MFC) piezoelectric plate. The fluid flows through the upstream bluff cylinder and produces alternating shedding vortices behind it. Vortex shedding produces periodic crosswise vortex-induced force to drive the fin and piezoelectric plate vibrating to generate electricity. An experimental platform was established and several prototypes of energy harvesters were fabricated. The experimental results show that, under different flow velocity domains, the harvesting effect of the bluff cylinder with a diameter of 30 mm is the most ideal for the energy harvester with a fin length of 20, 30 and 40 mm. When the fin length is 20 mm, the output voltage changes most smoothly. To obtain stable open circuit output voltage, the spacing distance between the bluff cylinder with a diameter of 25 mm and the fin should be controlled within 3D, while, the spacing distance between the bluff cylinder with a diameter of 30 mm and the fin should be controlled within 2D. When the bluff cylinder with a diameter of 30 mm, a spacing distance of 100 mm, and a flow velocity of 0.427 m/s, the maximum open circuit output voltage of 7.289 V can be obtained. The present work provides an effective experimental foundation for the research of underwater fin-shaped vehicle’s dynamic endurance.