Comparative analysis of flag based energy harvester undergoing extraneous induced excitation

Abstract

This study presents a detailed comparative analysis of the piezoelectric flexible plate under the influence of oscillating wakes of different bluff bodies. The piezoelectric plate is tested to determine the optimal configuration for energy harvesting from the wake flow of bluff bodies with different cross-sections in a low-speed closed-circuit wind tunnel. The Reynolds number is varied from 10000 to 75000 and the distance between the bluff body and plate is changed from 1D to 7D (where D is the diameter of the bluff body). The flutter of the plate without a bluff body is considered as a benchmark case and then subsequently the bluff bodies are introduced to see energy generation behavior. The results show that the bluff body caused a significant reduction of 50% in the flow speed as compared to the flutter case along with an improvement of 847% in energy harvesting output. Furthermore, selecting an appropriate bluff body ensures higher peak-to-peak flapping amplitude, which in turn produces a higher amount of electrical energy due to higher bending curvature and resultant strain produced in the piezoelectric plate. An increase of 125% in flapping amplitude is obtained using a bluff body compared to the flutter case. Furthermore, comparison within the various bluff bodies shows that change in cross-section has an enormous impact on output, and an increase of 515% in output power is obtained compared to the typical circular bluff body, which is more often quoted in the literature. Additionally, bending modes are identified and the variation in output power is linked with the flapping behavior of the piezoelectric plate, which is helpful in understanding the energy generation behavior of the piezo plate.