合成射流控制大攻角下翼型流动分离的频率特性研究

he frequency is one of important factors that influence the effects of a synthetic jet on controlling an airfoil's separation flow. With respect to the frequency characteristic of synthetic jets, NACA0015 is chosen as the research object in the paper, and the unsteady 2-D flow fields under synthetic jet actuation of different frequencies are simulated for a large attack angle(20 degree) and a Reynolds Number of 896000 based on the chord length. The impact of the actuation frequency on the effects of control by synthetic jets is investigated through analysis of the resulted flow fields. The results indicate that synthetic jets can effectively suppress flow separation of the airfoil, and enhance its aerodynamic performance. The influences of frequency on the lift and drag of an airfoil are different. The actuation of lower frequency is more preferable in increasing the airfoil's lift than the actuation of higher frequency with the maximum of lift coefficient reached when the dimensionless frequency is 1. The actuation of higher frequency performs better in reducing the drag compared with that of lower frequency with minimum drag coefficient achieved when the dimensionless frequency is 15. In addition, the optimal actuation frequency is not equivalent to the critical frequency of the separation zone of the uncontrolled airfoil.