间歇式俯仰转动扑翼的自主推进

Self-propulsion of a flapping foil powered by intermettent pitching motion

很多飞行和游动的生物采用主动驱动和被动滑行交替的运动方式。本研究通过比较间歇式和连续式驱动扑翼的自主推进性能,试图回答间歇式驱动能否节省能耗的问题。研究采用数值方法求解耦合的Navier-Stokes方程和扑翼运动的动力学方程。我们模拟了不同频率的连续式驱动以及给定频率不同占空比的间歇式驱动。结果表明,在达到相同平均推进速度条件下,如果推进速度较高间歇式驱动所需的能耗更低,如果速度较低则连续式驱动的能耗较低。我们还对比了连续式和间歇式驱动产生的不同流场结构。该研究得到的结果可以为高效仿生水下航行器的设计提供帮助。

Many animals adopt intermittent gaits(burst-and-coast or flapping-and-gliding)during flying or swimming.We compare the performances of self-propelled foils driven by intermittent and continuous pitching motions,and attempt to answer the question whether the intermittent gaits are more efficient.Numerical simulations are conducted by solving the NavierStokes equations together with the dynamics equations of the foil.We study cases of continuous pitching at various frequencies and also cases of intermittent pitching at a fixed frequency but different duty cycles.The results indicate that,for a given cruising speed,the continuous gait is more efficient at lower speed,while the intermittent gait is more efficient at higher speed.The different flow structures produced by the continuous and intermittent gaits are presented.The results obtained in this work can benefit the design of efficient bio-inspired underwater vehicles.