Formation Mechanism of Wall Jet Generated by Plasma Actuators in Quiescent Air

Flow control technology using dielectric barrier discharge plasma actuators stimulated by a sinusoidal alternating current (AC) high-voltage power supply has been studied explosively during the last two decades in the aerospace area for promoting the aerodynamics performance of the airplane. For the purposes of uncovering the controlling mechanism and enhancing the control effect of plasma actuators, the formation mechanism of the wall jet produced by plasma actuators in still air is studied by using a high-frequency particle image velocimetry system, a pressure-field microphone, and a high-accuracy phase-lock image freezing Schlieren technique. The discharge of the plasma actuator is mainly involved in the streamer discharge and the glowlike discharge during one sinusoidal AC period. It is found that the acoustic streaming flow generated by the plasma actuator lifts the airflow, and the body force generated by the plasma actuator pushes the airflow, during the streamer discharge stage. In addition, the airflow is drawn by the entrainment and pushed by the induced body force, respectively, during the glowlike discharge stage. Based on the body force and acoustic streaming flow, the influences of the plasma actuator on quiescent air are summarized as lift–push–push behavior.