Abstract The aim of this paper is to experimentally and numerically study a coupled-pitching hydrofoil under the fully activated mode. In the experimental study, the operating zones for the energy-releasing state and the energy-capturing state were identified. The phase relationship between the hydrodynamic torque and the angular velocity, which is determined by the combination of the primary and secondary pitching amplitudes, plays a key role in the switch of the energy releasing/capturing states. The primary pitching motion dominates the energy conversion of the hydrofoil under the fully-activated mode. The peak values of the averaged power coefficient and energy converting efficiency are achieved at 1.17 and 0.40, respectively. The numerical study found that the effective angle of attack determines the generation of the leading-edge and trailing-edge vortexes, and in turn affects the pressure distribution of the hydrofoil surface and torque generation. Compared to the traditional heaving-pitching mode, the coupled-pitching mode is horizontally affected by the negative torque because of the restriction of the primary pitching system, resulting in a lower energy capturing efficiency.

中文翻译：

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全激活模式下耦合俯仰水翼的实验和数值研究

摘要 本文的目的是对完全激活模式下的耦合俯仰水翼进行实验和数值研究。在实验研究中，确定了能量释放状态和能量捕获状态的操作区。由初级和次级俯仰幅度的组合决定的流体动力扭矩和角速度之间的相位关系在能量释放/捕获状态的转换中起关键作用。在完全激活模式下，主俯仰运动主导着水翼的能量转换。平均功率系数和能量转换效率的峰值分别达到 1.17 和 0.40。数值研究发现，有效攻角决定了前缘和后缘涡的产生，进而影响水翼表面的压力分布和扭矩的产生。与传统的纵摇模式相比，耦合纵摇模式由于主纵摇系统的限制，在水平方向上受到负扭矩的影响，导致能量捕获效率较低。