A comb-like beam based piezoelectric system for galloping energy harvesting

Abstract

This paper proposes a comb-like beam (CombBeam) based piezoelectric energy harvester (PEH) for harvesting wind energy by exploiting the galloping mechanism. The CombBeam-based PEH consists of a series of parasitic beams being mounted to a conventional cantilever beam with a piezoelectric transducer. A theoretical modelling method is established to simplify the proposed CombBeam-based PEH as a multiple-degree-of-freedom (MDOF) system. The conventional beam PEH is first represented as a single-degree-of-freedom (SDOF) system and the parasitic beam is then also converted into an equivalent SDOF system. A factor is derived to correct the reaction force of the SDOF model of the parasitic beam to address the force interaction between the host beam and the parasitic beam and a scaling factor is introduced to reflect the effect of the parasitic beam when being mounted onto the host beam at different positions. The complete mathematical formulations of the MDOF model for the CombBeam-based PEH under the base excitation and the aerodynamic force excitation are developed. Under the base excitation, a finite element model is built to first verify the MDOF model of the proposed CombBeam-based PEH in terms of derived equivalent lumped parameters, correction factors and scaling factor. A physical prototype of the proposed CombBeam PEH is then fabricated and the wind tunnel experiment is conducted to validate the MDOF model for predicting the energy harvesting performance under aerodynamic force excitation. The PEH undergoing galloping is referred as CombBeam-based GPEH to distinguish it with that under the base excitation. The results show that the CombBeam-based GPEH has the advantages over a conventional beam GPEH in reducing the cut-in wind speed from 2.24 m/s to 1.96 m/s and enhancing the power output around the optimal resistance for about 171.2% under a specific wind speed of 3 m/s.