八字形出口合成射流激励器机翼分离流控制

设计研制了一种适于机翼分离流动控制的八字形出口合成射流激励器,对其出口射流与主流的相互作用特性进行了研究,粒子图像测速仪(PIV)流场测试和边界层速度型测试结果揭示了其控制机制为促进边界层与主流的诱导掺混,提升边界层底层能量。利用该激励器阵列对NACA633-421三维直机翼模型开展了针对射流能量比Cμ和阵列位置两个参数的分离流控制研究,天平测力及翼型表面测压结果显示该激励器可有效抑制翼面流动分离、推迟失速迎角。在设计范围内,射流能量比Cμ值越大,控制效果越好,当Cμ=0.00168时,机翼最大升力系数提升了5.92%,失速迎角推迟了2.5°(激励器阵列位于0.3c处)。激励器阵列的弦向布置位置是一个重要控制参数,阵列位于0.3c处时最大升力系数提升量大于位于0.55c时。

Separation control of an airfoil by splayed-slit-synthetic-j et-actuator

A new type of splayed-slit-synthetic-jet-actuator(SSSJA)which is useful for sepa-ration flow control was designed.The core component of the acoustic excitation type actuator was a powerful loudspeaker(4 W).The j et velocity depends on two parameters of excitation frequency and voltage.Particle image velocimetry(PIV)and boundary layer probe was used to study the in-teraction between the jet flow and the main flow.Results revealed that the promotion of both flow dilution and the power of the boundary layer are responsible for the control effect.Flow con-trol on a three-dimensional NACA633-421 airfoil was then conducted to investigate the effect of two parameters of dimensionless energy ratio Cμand the location of the actuator array.Both pres-sure and force measurements data show the ability of SSSJA to reattach the separation flow and to delay the stall at high angles of attack.The control effect gets better along with the larger val-ue of Cμ.At Cμ= 0.00168,maximum of the lift coefficient and the stall angle were increased by 5.92% and 2.5°,respectively.Chordwise location of the actuator array was proved to be a vital parameter in separation flow control.The behavior of the array located at 0.3c is better than the one located at 0.55c.The difference in the control effect is determined by the relative position of the actuator array and the separation point.Experiments were conducted at the wind speed of v∞= 16m/s and the chord-based Reynolds number of Re= 2.7×105 .