翼型扑动气动特性数值模拟研究

Numerical Simulation of Aerodynamic Characteristics of Airfoil in Flapping State

以NACA0012翼型为研究对象,将扑动简化为俯仰、沉浮和前飞三种运动,通过求解NS方程,数值模拟了翼型扑动非定常流动。分析了减缩频率、平均俯仰角、俯仰振幅和沉浮振幅对翼型扑动气动特性的影响规律以及流场涡分布特性。结果表明:研究范围内,增大平均俯仰角和俯仰振幅或减小减缩频率和沉浮振幅能有效提高升力;减小平均俯仰角或增大缩减频率、俯仰振幅和沉浮振幅能有效增大向前推力;升力主要由下扑阶段产生,俯仰振幅大于等于平均俯仰角时,可获得升力及推力的综合效果;下扑过程中,前缘脱出涡并向后移动,强度逐渐变强,上扑过程中,涡逐渐耗散并继续向后移动。

Taking the NACA0012 airfoil as the research object, the movement was simplified to three kinds of motion: pitching movement floating movement and forward flight.By solving the NS equation, the unsteady flow field of airfoil in flapping state was numerically simulated. The influence of reduction frequency, average pith angle, pitch amplitude, floating amplitude on aerodynamic characteristics and the vortex distribution characteristics of flow field were analyzed. The results showed that: within the rang of research, increasing average pith angle and pitch amplitude or reducing reduction frequency and floating amplitude could effectively improve lift;reducing average pith angle or increasing reduction frequency, pitch amplitude and floating amplitude could effectively improve thrust;the lift was mainly generated by the downward stage,when [α1≥α0],could obtain the comprehensive effect of lift and thrust;during the downward stage, the vortex drawn out from the leading edge moved backward and the strength became strongergradually;during the upward stage, the vortex gradually dissipated and continued to move backward.