Increasing vortex-induced vibration-based energy harvesting using a nature-inspired bluff body: An experimental study

Abstract

The present study investigates the effect of changes on the cross-sectional geometry of a flow-induced vibration-based energy harvester. To do so, a bio-inspired geometry, which is adopted from the ‘Amaryllis’ flower is utilized. The fluid dynamic acting forces are numerically studied for the Reynolds numbers between 100 and 5000. Based on the attack angles of the so-called convex and concave petal cylinders are proposed, and three geometrical configurations with six, eight, and ten petals are considered. Furthermore, the concave and the convex cylinders’ vortex interaction and near wake flow are experimentally studied for two Reynolds numbers, employing Particle Image Velocimetry (PIV). A proportional relation was found between the enhancement of fluid dynamic forces and the shortening of vortex formation length that would improve Vortex-Induced Vibration (VIV). Finally, validated lift coefficients are employed in the analytically derived electromechanical equation of motion for the VIV-based energy harvester. It is shown that the newly proposed nature-inspired system can effectively increase the amount of harvested energy.