FLOW-INDUCED VIBRATION ENERGY HARVESTING BASED ON FINNED METASURFACE BLUFF BODY

The metasurface has a significant effect on the aerodynamic characteristics of bluff bodies. To promote the flow-induced vibration energy harvesting (FIVEH) performance of ordinary cylinder, several heights and numbers of finned metasurfaces are assembled on the ordinary cylinder and their effects on the FIVEH characteristics are investigated. The FIVEH experimental platform is set up and the piezoelectric energy harvesters are fabricated, the energy harvesting performance of different energy harvesters is analyzed experimentally. Based on the coupling model of vortex-induced vibration and galloping proposed by Tamura and Shimada (Tamura-Shimada model), the fluid-structure-electric coupling theoretical model for single-degree-of-freedom (SDOF) piezoelectric energy harvester is derived and the influence of aerodynamic parameters on the energy harvesting performance is elaborated. The computational fluid dynamics (CFD) model is conducted to simulate the vortex shedding patterns and flow field characteristics of different bluff bodies. The experimental results show that the finned metasurface has a remarkable impact on the dynamic characteristics of the bluff body: suppressing vortex-induced vibration (VIV) contributes to the high-level performance degradation of the energy harvesting, or transforming VIV to galloping, thus significantly improving the energy harvesting performance. When the wind speed exceeds the corresponding galloping cut-in speed, the piezoelectric energy harvester shows the galloping characteristics and occurs the stable limit cycle oscillation (LCO). The theoretical model can accurately predict the voltage characteristics. The CFD simulation results show that the finned metasurface can influence the wake vortex strength of bluff bodies then lead to a different dynamic response, thus affecting the energy harvesting performance. In addition, the influence of different interface circuits on the output power of piezoelectric energy harvesters is investigated, compared with the standard direct current (DC) circuit, the self-powered synchronous charge extraction (SP-SCE) circuit not only enhances the output power of the piezoelectric energy harvester but also provides more stable power output, the requirement of impedance matching is resolved and the flexibility of adjusting the high-performance piezoelectric energy harvester for practical applications is guaranteed.