Airfoil gust alleviation using a plasma actuator in low-speed wind tunnel test

Motivated by the demand of alleviating the impact of gusts during aircraft takeoff and landing, experimental investigations on an airfoil of GAW-1 gust alleviation using a symmetrically arranged dielectric barrier discharge plasma actuator were carried out in a low-speed wind tunnel with the help of force measurement, pressure measurement, and high-speed particle image velocimetry. The effect of gust alleviation using the plasma actuator was quantitatively evaluated, and the flow control mechanism of was revealed. The symmetrical plasma actuator which can be capable of producing a bi-direction quasi-wall jet with approximately equal velocities was mounted at the leading-edge of airfoil. The results indicated that the separation flow around the airfoil can be suppressed, and the stall angle of attack can be delayed by the plasma actuator under the gust environment. The stall angle of attack was delayed by 2° and the maximum lift coefficient was increased by 12% after plasma actuation. Meanwhile, the pressure oscillations caused by gusts can be suppressed by the plasma actuator, leading to the gust alleviation. Two typical flow structures, namely spanwise vortices and coherent structures are generated by the plasma actuator. The induced spanwise vortices near the leading-edge of airfoil and the induced coherent structures in the vicinity of the wall surface play an important role in the gust alleviation. The process of gust alleviation based on plasma actuation can be divided into three stages. Initially, the induced vortices can promote the mixing between low-energy airflow near the wall and the mainstream, thereby injecting momentum into the boundary layer during the first stage. In the second stage, a relatively enclosed region produced by the interaction between the induced vortices and the incoming flow was established and was able to create virtual aero-shaping, thereby changing the shape of the leading edge of the airfoil. Finally, a series of coherent structures transported induced momentum from the leading edge of the airfoil to the trailing edge in the third stage. The present results provide methodological support for establishing the gust alleviation technology for unmanned aerial vehicles based on plasma actuation.