Oscillating foils in synchronized pitch/heave motions can be used to harvest hydrokinetic energy. By understanding the wake structure and its correlation with the foil kinematics, predictive models for how foils can operate in array configurations can be developed. To establish a relationship between foil kinematics and wake characteristics, a wide range of kinematics is explored in a two-foil tandem configuration with interfoil spacing from four to nine chord lengths separation and multiple interfoil phases. Using data from experiments and simulations, an in-depth wake analysis is performed and the mean velocity and the turbulent kinetic energy are quantified in the wake. With this energy quantification, the trailing foil efficiency is modified to account for the mean flow in addition to the energy transported by the coherent leading edge vortices (LEVs) shed from the leading foil. With the mean wake velocity, a predictive wake model is able to distinguish three regimes through analyzing trailing foil efficiency profiles and the strength of the primary LEV shed from the leading foil. Dividing the wake into regimes is an insightful way to narrow the range of foil kinematics and configurations and improve the energy harvesting in a two-tandem foil array.

中文翻译：

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串联振荡箔中的尾流箔相互作用和能量收集效率

同步俯仰/升沉运动中的振荡水翼可用于收集流体动能。通过了解尾流结构及其与箔运动学的相关性，可以开发箔如何在阵列配置中运行的预测模型。为了建立翼片运动学和尾流特性之间的关系，在具有四到九个弦长分离的翼片间距和多个翼片间相位的两翼串联配置中探索了广泛的运动学。使用来自实验和模拟的数据，进行深入的尾流分析，并量化尾流中的平均速度和湍流动能。通过这种能量量化，除了从前翼脱落的相干前缘涡 (LEV) 传输的能量之外，后翼效率被修改以考虑平均流动。利用平均尾流速度，预测尾流模型能够通过分析尾翼效率曲线和主 LEV 从前翼脱落的强度来区分三种状态。将尾流划分为多个状态是缩小箔运动学和配置范围并改善双串联箔阵列中的能量收集的一种有见地的方法。