Spatial–temporal evolution of the pressure field generated by a plasma actuator in quiescent air

Abstract

Dielectric barrier discharge plasma actuators, capable of generating quasi-steady wall jets, are well suited for flow control on various problems. Compared with the detail related to the induced velocity field, there are limited results available for the pressure field created by the plasma actuator. However, the profound merits of understanding the evolution of the pressure field are to reveal the controlling mechanism. Here, the time-averaged and the phase-averaged pressure field distributions are obtained by using a pressure reconstruction method based on the velocity field from particle image velocimetry experiments. According to the discharge regimes, the formation mechanism of the pressure field is discussed. During the streamer discharge stage, the pressure close to the upper electrode is decreased under the influence of the induced heating caused by the high-frequency and high-amplitude pulsed current, leading to the air above the plasma actuator being drawn toward the wall surface. During the glow discharge stage, under the effect of suction generated by the streamer discharge, the pressure near the wall is increased and the plasma actuator generates a favorable pressure gradient, which provides advantageous conditions for the airflow acceleration. During the discharge quenching stage, the effect of the plasma actuator vanishes and the influence of viscous force is strengthened. Therefore, the adverse pressure gradient is gradually formed and the velocity of the wall jet is decreased compared to that of the glow discharge stage. The change of pressure field in a period can be summarized into three processes: pressurization, pressure release, and pressure recovery.