TWO-ELEMENT AIRFOIL GUST ALLEVIATION USING A PLASMA ACTUATOR

Flow control technology using dielectric barrier discharge (DBD) plasma actuators is an active flow control technology based on plasma actuation and has some advantages, such as short response time, simple structure, low consumption power, and no need for additional air source devices. Motivated by the demand of improving the endurance performance and promoting the development of low altitude unmanned aerial vehicles (UAV), the investigations on a two-element airfoil of GAW-1 gust alleviation by using a DBD plasma actuator driven by a sinusoidal alternating current (AC) were carried out with the help of numerical simulation method. The control effect of DBD plasma actuator was evaluated by aerodynamic forces and the gust alleviation mechanism was uncovered by instantaneous flow fields. An asymmetrical DBD plasma actuator was placed at the trailing-edge of airfoil and the direction of the quasi-steady wall jet produced by the plasma actuator was opposite to the incoming flow. The maximum reduction of the fluctuation of lift coefficient was approximately 51.6% after applying the DBD plasma actuation, which indicated that the effect of gust on the airfoil can be weaken effectively by the plasma actuator. In addition, the shape factor of boundary layer was increased, the length and the area of separation zone was prolonged and was extended, respectively, with the help of plasma actuator. Moreover, it is believed that the wall jet and the vortex both created by the plasma actuator play an important role in gust alleviation. The pressure difference between the upper and lower airfoil surfaces was reduced by the induced wall jet which hindered the development of incoming flow, accelerated and deflected the streamline of the lower airfoil surface deflect upwards, leading to reduce the lift coefficient of airfoil. Meanwhile, a virtual hump generated by the induced vortex expanded the area of separation zone. The present results lay a technical foundation for promoting the aerodynamic performance of low altitude UAV.