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中文核心期刊

基于翅片超表面钝体的流致振动俘能特性研究

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

  • 摘要: 超表面结构对钝体气动力特性有显著影响. 为了增强普通圆柱的流致振动俘能特性, 在圆柱表面装配不同高度和不同数量的翅片超表面并研究其对流致振动俘能特性的影响. 搭建流致振动俘能实验平台并制作压电俘能器, 实验分析了不同俘能器的俘能特性. 基于Tamura和Shimada提出的涡驰耦合模型 (Tamura-Shimada模型), 推导单自由度 (single-degree-of-freedom, SDOF) 压电俘能器流−固−电耦合理论模型, 并研究了俘能器的气动力参数对其俘能特性的影响. 建立计算流体动力学 (computational fluid dynamics, CFD) 模型, 仿真分析了不同钝体的旋涡脱落模式和流场特性. 实验结果表明翅片超表面能够显著改变钝体的动力学响应: 抑制涡激振动从而降低俘能特性或从涡激振动转变为驰振从而显著增强俘能特性. 当风速超过相应驰振起振风速后, 俘能器出现驰振特征并表现为稳定的极限环振荡 (limit cycle oscillation, LCO). 理论模型能够较为准确地预测俘能器的电压响应. 通过仿真分析可知, 翅片超表面能够显著改变钝体后方的旋涡强度, 导致其动态响应发生变化, 最终影响其俘能特性. 此外, 研究了不同接口电路对压电俘能器输出功率的影响, 与标准直流 (direct current, DC) 电路相比, 自供能同步电荷提取 (self-powered synchronous charge extraction, SP-SCE) 电路不仅可以提升压电俘能器的输出功率同时也可以提供更加稳定的功率输出, 消除了阻抗匹配的要求, 保证了高性能压电俘能器在实际应用中的灵活性.

     

    Abstract: 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.

     

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