Novel galloping-based piezoelectric energy harvester adaptable to external wind velocity

Abstract

In this study, a novel galloping-based piezoelectric energy harvester adaptable to external wind velocity (GPEHAW) is proposed. The purpose of developing the GPEHAW is two-fold: (1) improve the power density in a high wind velocity regime and (2) lower the critical wind velocity for galloping in a low wind velocity regime. The bluff body in the GPEHAW is designed to be movable, under an elastic constraint, in axial direction on a flexible beam, and a set of springs is mounted between them. The dynamics of this bluff body are governed by the unbalance between the drag, centrifugal, spring, and friction forces. A nonlinear aero-electro-mechanical model is derived using the extended Hamilton principle, and its analytical solution is obtained using a perturbation technique: the method of multiple scales. The moving mechanism of the bluff body is thoroughly investigated under various force conditions, followed by a numerical analysis and preliminary experimental validation. Subsequently, the mathematically obtained coupled behavior of the GPEHAW system is compared with the experimental results. Furthermore, a comprehensive study is performed to investigate the influence of the distance traveled by the bluff body (equivalent to the effective beam length) on the behavior of the GPEHAW system, with a special focus on the critical wind velocity for galloping, transverse displacement, average power, and power density. The results show that the proposed system exhibits an excellent energy performance, an increase in power density by 70.2%, and a mean power density improvement rate (MPDR) of 23.4%, compared with the conventional system (equipped with a fixed bluff body). We consider that the findings in this study provide a useful guideline for designing efficient galloping-based piezoelectric energy harvesters, which would be particularly effective in an urban environment. © 2020 Elsevier Ltd