A Parametric Study of Piezoelectric Energy Harvesting by Vortex Induced Vibration of a Pair of Cylinders

Abstract

The design of a piezoelectric based device that uses interference bluff body to harvest wind energy is presented. Different prototypes including cantilever beam, cylinder as oscillating body, and cylinder as interference body were used and tested to investigate the effects of interference bluff body’s properties such as the size and distance from fix oscillating body on the performance of energy harvesting system. To compare the frequency of oscillating beam and its natural frequency, a numerical simulation based on Finite Element Method was performed to obtain the natural frequency of cantilever beam. It was found that the energy harvester can be greatly improved by placing a fixed bluff body as interference bluff body in upstream of the oscillating bluff body. Through experimental tests, this study reveals that both diameter of interference cylinder and the distance between oscillating and interference cylinder play a key role in the energy harvester’s performance. Moreover, two different modes of oscillation were observed, depending on diameter of interference cylinder and its distance from bluff body. For all cases, the Fast Fourier Transform (FFT) analysis was used to monitor the frequency of oscillating cylinder and these values were compared with the natural frequencies obtained by Finite Element Method’s analysis. The results showed that the shorter beams oscillate with a frequency of about 5 Hz, close to the natural frequency of 6Hz, while the longer beams oscillate with a frequency of about 2.2 Hz, close to the natural frequency of 2.17Hz.