Experimental hydrodynamic investigations on the effectiveness of inverted flag-based piezoelectric energy harvester in the wake of bluff body

Abstract

The flapping motion and energy harvesting performance of an inverted flag in the wake of a bluff body are experimentally studied. The experimental measurements are carried out by changing the bending rigidity, streamwise gap (which represents the distance from the bluff body to the tip of the flag), and Reynolds number to explore their impact on the flapping dynamics and power generated by the piezoelectric flag. The optimal values of the Reynolds number, bending rigidity, and streamwise gap are determined based on the power generated. Variation in the flapping modes ranging from continuous to deflected mode is observed. The results show that the inverted flag having a high peak-to-peak amplitude is preferred for piezoelectric energy harvesting as it produces high strain energy. It is also demonstrated that the vortices shed by the upstream bluff body have a strong effect on the flapping amplitude of the downstream inverted flag. This research would help in determining the most effective streamwise position of the inverted flag behind the bluff body and bending rigidity for generating voltage at low Reynolds numbers.