Fluid-structure interaction of a fully passive flapping foil for flow energy extraction
Fluid-structure interaction of a fully passive flapping foil for flow energy extraction
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DOI：
10.1016/j.ijmecsci.2020.105587
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发表时间：
2020-07
影响因子：
7.3
通讯作者：
M. N. M. Qadri-M.-N.-M.-Qadri-97858644;F. Zhao;Hui Tang
中科院分区：
文献类型：
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作者：
M. N. M. Qadri-M.-N.-M.-Qadri-97858644;F. Zhao;Hui Tang
实验研究了一种新型扑翼流能收集器的流固耦合和能量提取性能。与大多数现有概念不同的是，该装置可以通过箔片的完全被动拍打运动从流动中提取能量，即箔片的起伏和俯仰运动是由流动引起的，而无需使用任何执行器。在不同的流量和操作条件下，研究了铝箔的动力学和吸能性能。研究发现，当雷诺数接近105时，该装置的切割速度为0.45 m/s，在0.55 m/s的水流中可产生约1 W的平均功率，功率转换效率为32.5%。详细的FSI研究表明，起伏和俯仰运动对能量收集都有积极的贡献。升沉速度在每个纯升沉阶段结束时达到极值，而升沉力在每次冲程反转结束时达到极值，导致相位差接近90°。因此，升沉功率在纯升沉阶段为正，而在冲程反转阶段为负。俯仰速度和俯仰力矩均在冲程逆转结束时达到峰值，从而产生一个显著的俯仰功率峰值。研究还发现，与翼型的有效迎角相比，扑动过程中产生的前缘涡对翼型的动力学影响非常有限。参数化研究表明，随着翼型枢轴向尾缘移动，平均升沉功率和平均俯仰功率均增加。因此，总功率显著增加。当箔片俯仰幅度从30°增加到60°时，也观察到相同的趋势。相反，在0.46 ~ 0.69 m/s之间存在最佳水速，此时的功率转换效率最大。
We experimentally investigated the fluid-structure interaction (FSI) and energy extraction performance of a novel flapping-foil based flow-energy harvester. Different from most of existing concepts, this device can extract energy from flows through a foil's fully passive flapping motion, i.e., the foil's heaving and pitching motions are induced by the flow without using any actuator. The foil's dynamics and energy extraction performance were studied under various flow and operating conditions. It was found that, when operating at the Reynolds number near 105, the device has a cut-in speed of 0.45 m/s and can generate a mean power of about 1 W in a water flow of 0.55 m/s, leading to a power conversion efficiency of 32.5%. Detailed FSI studies revealed that both the heaving and pitching motions can make positive contributions to energy harvesting. The heaving velocity reaches its extremes at the end of each pure heaving phase, whereas the heaving force reaches its extremes at around the end of each stroke reversal, leading a phase difference of nearly 90°. As such, the heaving power is positive in the pure heaving phases but negative in the stroke reversal phases. Both the pitching velocity and pitching moment peak at the end of stroke reversals, hence generating a significant peak in the pitching power. It was also found that, compared to the foil's effective angle of attack, the leading-edge vortices produced during flapping have a very limited impact on the foil's dynamics. A parametric study revealed that, as the foil's pivot axis is moved towards the trailing edge, both the mean heaving power and the mean pitching power increase. As a result, the total power increases significantly. The same trend was also observed when the foil's pitching amplitude increases from 30° to 60°. On the contrary, it seems that there exists an optimal water speed between 0.46 and 0.69 m/s, at which the power conversion efficiency is maximum.