Vortices induced by a dielectric barrier discharge plasma actuator under burst-mode actuation

The formation and motion of vortices generated by a dielectric barrier discharge (DBD) plasma actuator under periodic burst-mode actuation are investigated. The flowfield is studied using particle image velocimetry and schlieren visualization. The induced flowfield is very different from the single starting vortex generated by turning on a continuous steady-state actuation of the DBD actuator. A train of periodic vortices is formed by the periodic burst-mode actuation, with each burst cycle generating one vortex that travels along and away from the wall. The effects of the burst frequency and duty-cycle ratio on the vortex motion and structure are studied, and similarity laws are discovered. The velocity at which the vortex moves is shown to be independent of the duty-cycle ratio of the actuation. The velocity component along the wall, however, is found to increase with the burst frequency. A time-averaged wall jet velocity based on the actuation time during each burst cycle is identified and found to be independent of the burst frequency but increase with the duty-cycle ratio of the actuation. Self-similar patterns of the vortex flowfield are demonstrated for a short time duration after the vortex is formed within each burst cycle.