Investigating the Effect of an Elliptical Bluff Body on the Behavior of a Galloping Piezoelectric Energy Harvester

The extraction of energy from naturally oscillating objects has recently garnered considerable attention from researchers as a robust and efficient method. This study specifically focuses on investigating the performance of a galloping piezoelectric micro energy harvester (GPEH) designed for self-powered microelectromechanical systems (MEMS). The proposed micro energy harvester comprises a cantilever beam composed of two layers, one being silicon and the other being a piezoelectric material (PZT-5A). The harvester is equipped with an elliptical tip cylinder, and the entire system is modeled using lumped parameters. To simulate the response of the system, the size-dependent coupled governing equations are numerically solved, enabling the extraction of the dynamic behavior of the energy harvester. Furthermore, computational fluid dynamics (CFD) simulations are employed to model the effect of the flow field on the oscillations of the beam. Different aspect ratios (AR) of the elliptical cylinder are taken into account in the simulations. The study examines the impact of the aspect ratio and mass of the elliptical tip cylinder on the harvested power of the system. The results demonstrate a notable decrease in the extracted power density for AR = 1 and 2 compared to higher aspect ratios. In the case of AR = 5, the device exhibits an onset wind speed of 7 m/s. However, for AR = 10, the onset wind speed occurs at a lower wind velocity of 5.5 m/s, resulting in a 66% increase in extracted power compared to AR = 5. Additionally, the results reveal that increasing the normalized mass from 10 to 60 results in a 60% and 70% increase in the output power for AR = 5 and AR = 10, respectively. This study offers valuable insights into the design and optimization of galloping piezoelectric micro energy harvesters, aiming to enhance their performance for MEMS applications