低雷诺数下层流分离的等离子体控制

为有效控制层流分离特性，消除或减弱低雷诺数时小迎角下的升力非线性现象，改善翼型升力特性，并通过翼型的上表面转捩带与油流显示测量对等离子体激励控制机理进行阐述，对厚度为16%椭圆翼型低雷诺数下的气动特性进行了风洞试验研究。在此基础上，在上表面前缘10%弦长处布置激励器，通过压力分布测量观察等离子体激励对层流分离的影响。试验结果表明：当翼型上表面仅发生层流分离时，等离子体激励和转捩带的作用类似，可以有效延迟或者消除后缘层流分离，从而增加升力；当翼型上表面出现层流分离气泡并发生再附现象时，等离子体可以有效减小或者消除层流分离泡的范围，从而减小升力；通过控制层流分离，占空循环等离子体激励可以实现对低雷诺数小迎角下的升力的线性控制。

Laminar separation control at low Reynolds numbers using plasma actuation

In order to control the laminar separation effectively and eliminate or decrease the nonlinearities of the lift curve, the mechanism is detected using pressure measurements and surface oil visualization measurements on the tripped airfoil. An experimental study of an elliptic airfoil with 16% thickness is performed in wind tunnel. Based on the baseline airfoil aerodynamics, an alternating current single dielectric barrier discharge plasma actuator set at 10% chord is designed, combined with surface pressure distribution measurements. The results show that the plasma actuator would re-energize the boundary layer, thereby delay the trailing-edge laminar boundary layer separation and result in the enhancement of the lift like a trip strip. When the laminar separation bubble occurs at trailing or leading edge region of the airfoil, the plasma actuation can eliminate or decrease the bubble, thus leading to a reduction in the airfoil lift. The linear proportional control is achieved with the enhancement and reduction lift changes by duty-cycled plasma actuation.