Modeling and validation of a tri-section beam based multi-directional galloping energy harvester
Cuipeng Xia, Lihua Tang, Yi Wu, Guobiao Hu, Peilun Yin, Kean C. Aw, Daniel J. Inman
Abstract
A conventional galloping-based wind energy harvester is typically restricted to capturing energy from a single wind direction, making it inefficient in the unpredictable conditions of natural environments. This research presents comprehensive theoretical modeling of a novel galloping-based piezoelectric energy harvester featuring a tri-section beam structure to harvest wind energy from different flow directions by utilizing various vibrational modes. First, the global mode method (GMM) is employed to derive the natural frequencies and mode shapes, validated by comparison with the finite element method (FEM). Computational fluid dynamics (CFD) simulation is then conducted to analyze the aerodynamic characteristics of the bluff body under different incident wind directions, providing essential transverse aerodynamic force coefficients. With these modal parameters and aerodynamic coefficients, subsequently, the fully coupled aero-electro-mechanical model is established to evaluate the energy harvesting performance with varying wind speed and direction. The results show that the developed tri-section beam based galloping energy harvester can effectively capture wind energy from multiple directions with different vibration modes being triggered. The established theoretical model can successfully predict the triggering of different modes and accurately evaluate the electrical outputs in different wind conditions, which are validated by wind tunnel experiments. In addition, it is found that higher voltage and power outputs are achieved when galloping is triggered in the second order bending mode with a higher cut-in wind speed, as compared to the first order bending mode. The modelling and design of the developed multi-directional galloping energy harvester offers a feasible approach for harnessing flow energy in natural environments with unknown, varying wind conditions.