平板/锯齿型Gurney襟翼对NACA0012翼型增升实验研究

 在Re 为211@10⁶ 情况下进行的NACA0012 翼型Gurney 襟翼增升效应风洞实验研究表明, Gurney襟翼可使升力有很大提高, 0.5%平均气动弦长襟翼在C_L> 11 0 后即可提供较高的升阻比, 当C_L = 11 35 时,2%平均气动弦长襟翼获得了35%的最大升阻比增量; 翼型表面压力分布结果显示, Gur ney 襟翼增加了上翼面的吸力, 同时下翼面压力增强, 因而升力提高; 尾流速度型显示Gur ney 襟翼导致流经上翼面的流体在其后有明显下偏转, 这表明翼型有效弯度增大了; 襟翼上开出锯齿会同时导致升力和阻力下降, 但升阻比是否会提高则应视其是否更接近最佳高度的有效迎风面积。Gur ney 襟翼的最佳应用场合为中高升力系数情况( 如起飞、降落等), 在中小升力系数情况下不宜使用。

Experimental Investigation of Lift Enhancement on a NACA0012 Airfoil Using Plate/Serrated Gurney Flaps

An experimental wind-tunnel investigation was undertaken to determine the effects of Gur ney flaps on aNACA0012 air foil at a chord Reynolds number of 21 1@10⁶ . In comparison with the clean configuration r esults, theGurney flap increased the lift significantly. A higher lift-to-drag ratio was obtained by t he 0.5% C flap when thelift-coefficient exceeds 11 0, and a maximum increment of lift-to-drag ratio was obtained by the 2% C flap at a liftcoefficient of 1135. The pressure distribution r esults showed that the Gurney flap increased the suction of t he uppersurface and the pressure of the lower surface, and thus the total lift. The wake velocity profile indicated a significantdown-turning of the stream over the upper surface of t he airfoil, and this revealed t hat the camber of the airfoil wasincreased by t he Gur ney flap. When serrated, Gurney flaps produced less lift and drag than not serr ated ones, butt he variation of the lift-to-dr ag r at io depends on the effective ar ea of t he flaps1 T he Gurney flap should be employedat moderate2to2high lift-coefficient conditions such as takeoff and landing, while not advisable at low-to-moderatelift-coefficient conditions.