前缘附近微小板对S809翼型气动性能的影响

翼型在较大攻角下会发生失速，产生流动分离，这将直接影响翼型气动性能。对此，采取在雷诺数Re=1×106的条件下，在S809翼型前缘点附近不同位置处设置微小板，改变微小板的板长、振动振幅和频率，探究其对S809翼型气动性能的影响。结果表明：静止时，微小板的板长尺寸对控制效果影响显著，当位置和尺寸选取最优时，S809翼型在22°攻角下升阻比提升2倍左右；对抑制流动分离效果不佳的尺寸较小的静止板施加以合适振幅和频率的振动后，可以有效地抑制翼型的流动分离，得到增加升力、减小阻力的效果。

Effect of a tiny sheet in front of its leading edge on aerodynamic performance of S809 airfoil

The stalling and flow separation of airfoils at large attack angle directly affect the aerodynamic performance of the airfoils. The measure of setting a tiny sheet around the suction surface of a S809 airfoil at Re=1×106 was discussed by numerical simulation. The length, oscillating amplitude and frequency of the tiny sheet were three main parameters to be considered. A physical analysis of the ?ow ?elds was performed to illustrate the mechanism of ?ow control for the improvement of airfoil aerodynamic performance. The results suggest that: when the tiny sheet is stationary, the size of the tiny sheet has a significant influence on the control effect. When the optimal position and size of the tiny sheet have been properly selected, the lift-drag ratio of the S809 airfoil is increased by about 2 times at the angle of attack of 22°. The control effect for flow separation is not good when the smaller size tiny sheet is stationary, but the control effect will be good when it is oscillating: the size of flow separation bubble is significantly reduced, the lift coefficient is increased, and the drag coefficient is effectively reduced, so the aerodynamic performance of the airfoil is further significantly improved.