Dynamic Behavior of Galloping Micro Energy Harvester with the Elliptical Bluff Body Using CFD Simulation

Abstract

Energy extraction from flow-induced oscillations based on piezoelectric structures has recently been tackled by several researchers. This paper presents a study of the dynamic behavior analysis and parametric characteristics of a galloping piezoelectric micro energy harvester (GPEH) applied to self-powered micro-electro-mechanical systems (MEMS). The mechanical performance of a piezoelectric micro energy harvester cantilever beam with two layers of elastic silicon and piezoelectric (PZT-5A) attached to a tip elliptical cylinder is numerically simulated. Using size-dependent beam formulation on the basis of the modified couple stress theory and Gauss’ law, the coupled electro-mechanical non-linear governing equations of the energy harvester are obtained. The mode summation and Galerkin methods are used to derive the extracted power from the system. The study also models the flow field effect on the beam oscillations via CFD simulation. The effect of elliptical cylinder mass, damping ratio, beam thickness, and load resistance on the dynamic behavior and harvested power of the system is studied. Findings reveal that increasing the normalized tip mass from 0 to 0.5 and 1 increases the output power density from 0.12 to 0.2 and 0.22, respectively, and the corresponding electrical load resistance of maximum power increases from 175 to 280 kΩ and 375 kΩ, respectively. An approximately linear relation between the elliptical cylinder mass and the load resistance is observed. By increasing/decreasing the cylinder mass, the required electrical load resistance for maximum output power proportionally changes. The damping analysis shows that a higher damping ratio increases the onset velocity of galloping and decreases the extracted power.