针对单级环量控制气动效率低、能耗高的不足，设计了一种多级环量增升机翼。通过测力实验，对比研究了多级环量控制在增升方面的控制效果，并且在多级环量控制基础上研究了吹气系数对机翼气动力性能的影响。通过PIV (Particle Image Velocimetry)实验，研究了临界吹气系数前后的流动控制机理。测力结果表明，相比于无环量控制，在输入流量Q=9.84 m3/h时，三喷口吹气（多级环量控制）的最大升阻比提高了95.3%；随着吹气系数的增加，环量控制先后经历分离控制和超环量控制两种阶段，在分离控制阶段，升力系数随吹气系数的增加显著提升，阻力系数先减小后增大；在超环量控制阶段，随吹气系数的增加，升力系数提升效果减弱，阻力系数逐渐增大最后趋于平缓。PIV研究结果表明，在分离控制阶段，随吹气系数的增加，射流分离点沿圆弧后缘下移，增大了速度环量使升力提高，并且尾迹区范围减小、速度提升，使阻力减小；在超环量控制阶段，高速射流使后缘流线产生了大的偏转曲率，起到了气动襟翼的作用，并且在大迎角下兼具控制流动分离的效果。此外，引入了有效升阻比的概念对多级环量增升机翼的气动效率进行评估，发现在分离控制阶段多级环量控制机翼的功率系数较小、有效升阻比最大，气动效率最高。
Aiming at the shortage of low aerodynamic efficiency and high energy consumption of single-stage circulation control, a multistage circulation lift wing was designed. Through the force measurement experiment, the control effect of the multistage circulation control in the aspect of lift increase are compared, and the influence of the blow coefficient on the aerodynamic performance of the wing is studied based on the multistage circulation control. The flow control mechanism before and after critical blowing coefficient was studied by PIV (Particle Image Velocimetry) experiment. The force measurement results show that the maximum lift-to-drag ratio of three slot blowing (multistage circulation control) is improved by 95.3% compared with that of non-circulation control when the input flow Q=9.84 m3/h. With the increase of blowing coefficient, the circulation control goes through two stages: separation control and super circulation control. In the separation control stage, the lift coefficient increases significantly with the increase of blowing coefficient, and the drag coefficient decreases first and then increases. In the super circulation control stage, with the increase of blowing coefficient, the lifting effect of lift coefficient is weakened, while the drag coefficient increases gradually and finally flattens out. The PIV results show that, in the separation control stage, with the increase of blowing coefficient, the jet separation point moves down along the back edge of the arc, increasing the velocity circulation to improve the lift, and the wake area decreases and the velocity increases to reduce the drag. In the super circulation control stage, the high-speed jet makes the trailing edge streamlines produce large deflection curvature, which plays the role of pneumatic flap, and has the effect of controlling flow separation at high Angle of attack. In addition, the concept of effective lift-to-drag ratio is introduced to evaluate the aerodynamic efficiency of the mul-tistage circulation control wing. It is found that the power coefficient of the multistage circulation control wing is small, the effective lift-to-drag ratio is the largest, and the aerodynamic efficiency is the highest in the separation control stage.
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