A Piezoelectric Wind Energy Harvester with Interaction Between Vortex-Induced Vibration and Galloping

It is of significance to lower the cut-in speed of piezoelectric wind energy harvesters (PWEHs) to expand the applications. Previous experiments have verified that the cut-in speed may be effectively lowered by the interaction between vortex-induced vibration (VIV) and galloping. This work derives a mathematical model of the VIV-galloping interactive PWEHs by considering the effect of the piezoelectric layer on the equation of motion and adding an electrical equation to relate the electrical output with the deformation. Numerical simulations show that, with the increase of the side length of the square cross-section of the bluff body, the harvesters demonstrate a behavior transition from separated to interacted VIV and galloping. For a VIV-galloping interactive PWEH, the electrical responses predicted by the interactive model are greatly different from those predicted by VIV and galloping models. Experimental results show that the interactive model successfully predicts the interaction between VIV and galloping. Moreover, the simulated electrical outputs agree well with the experiments. Therefore, the proposed interactive model provides a useable tool to design a VIV-galloping interactive PWEH.