A multi-directional and multi-modal galloping piezoelectric energy harvester with tri-section beam

Abstract

A traditional wind energy harvester based on galloping can only scavenge wind energy from one specific direction, which fails to work efficiently in a natural erratic environment. In this study, we propose a galloping-based piezoelectric energy harvester that can collect energy from wind flow in a wide range of incident directions with multiple vibrational modes being excited. The proposed harvester is composed of a tri-section beam with bonded piezoelectric transducers and a square bluff body with splitters. Finite element analysis of the tri-section beam structure is first performed and confirms the clustered natural frequencies that ease the excitation of different modes. Then, the aerodynamic characteristics of various bluff bodies is conducted through CFD to compare the capability of galloping. Finally, the wind tunnel experiment is carried out to test the wind energy harvesting performance by utilizing the harvester's multi-modal characteristics. The results demonstrate that the proposed harvester can scavenge wind energy in multiple directions with the capability of galloping in multiple vibrational modes, and superior performance is achieved when the second bending mode is triggered. The novel design of the harvester from this work provides a viable solution for harvesting wind energy in a natural environment with varying wind conditions.