Following our previous work [Int. J. Mech. Sci. (2020), vol. 177, 105587], we searched the best power extraction performance of a novel flow-energy harvester, which utilizes a fully passive flapping foil to extract energy from air/water flows. A series of water-tunnel experiments were conducted on the same test model at the Reynolds number around ${10}^5$. Through investigating the effects of two unexplored key parameters, a higher overall maximum power conversion efficiency of $42.7\%$ was obtained at water speed 0.71 m/s and foil pitching amplitude ${60}^{\circ },$ corresponding to a larger mean power output of about 1.51 W. A quasi-steady theoretical model was also developed to fast predict the system performance in a larger parameter space. It was found that, in addition to typical dynamics, i.e., a flapping cycle includes two pure-heaving phases and two stroke-reversal phases, the foil system can also continuously operate in a “no-pure-heaving” zone where a flapping cycle only includes two successive stroke-reversal phases. Through these experimental and theoretical studies, a useful guideline was proposed on the design and operation of the foil system.

遵循我们以前的工作[Int。J.机甲 科学 （2020），第一卷。177，105587]，我们研究了新型流动能量收集器的最佳功率提取性能，该收集器利用完全无源的拍打箔片从空气/水流中提取能量。在相同的测试模型上以雷诺数为单位进行了一系列的水隧道实验${10}^5$。通过研究两个未探索的关键参数的影响，获得了更高的整体最大功率转换效率：$42.7％$ 以0.71 m / s的水速和箔片俯仰幅度获得 ${60}^{\circ }，$对应于约1.51 W的较大平均功率输出。还开发了准稳态理论模型来快速预测较大参数空间中的系统性能。已经发现，除了典型的动力学，即拍打周期包括两个纯隆起阶段和两个冲程反转阶段之外，箔系统还可以在“无纯隆起”区域连续运行，在该区域中出现拍打周期仅包括两个连续的行程反转阶段。通过这些实验和理论研究，提出了有关箔系统设计和操作的有用指南。