涡致振动型风力压电俘能器流场数值模拟与试验

基于涡致振动原理设计了一种风力型压电俘能器,通过串列配置的双绕流圆柱增加进气道内流场的压强波动,以Helmholtz共振腔作为尾流区域的风压谐振放大装置,利用PVDF压电薄膜直接将湍流引起的持续性压强波动转换为电能。采用计算流体力学数值方法,分析了在不同风速下压电俘能器内部流场的流体动力学行为。数值分析及试验结果表明:在相同风速下,当耦合因子L/D=2.2时,双绕流圆柱引起的压强波动最大,可达到单绕流圆柱的2倍;Helmholtz共振腔内气体在振荡流的作用下产生谐振后,腔内气体压强的幅值随风速的增加而增大,但振动频率均相同且为共振腔的固有频率。

Numerical Simulation and Experiment of a Wind Piezoelectric Energy Harvester Based on Vortex-induced Vibrations

A wind piezoelectric energy harvester based on vortex-induced vibrations was studied. The tandem arrangement of two circular cylinders was designed to enhance the amplitude of the pressure fluctuation. The Helmholtz resonator was used for magnifying the wind pressure in the wake region. The flow energy was converted into electrical energy by piezoelectric conversion with oscillation of a PVDF film. The fluid dynamics behaviors of the internal flow field subjected to different wind speeds were analyzed using computational fluid dynamics(CFD) numerical method. Numerical analysis and experimental results showed that the pressure fluctuation in the case of two circular cylinders could reach up to nearly 2 times as that of a single circular cylinder, when the coupling factor L/D=2.2 and subjected to the same wind speed. As the gas in the cavity induced by the oscillatory flow, the gas pressure increased with the wind speed while the vibration frequency kept the same with the natural frequency of the resonator.