A burst wave-induced plasma actuator for controlling separated flow over a backward-facing step at low Reynolds numbers

• Transient behavior of a burst wave-induced plasma actuator (BWPA) was investigated.
• The velocity growth and decay induced by BWPA were expressed by simple functions.
• Backward-facing step flow separation was suppressed well by periodic disturbance.
• The relations among BWPA operating parameters and reattaching behavior were shown.

Recently, dielectric barrier discharge plasma actuators have been extensively studied as flow control devices for controlling separated flow. It is known that a periodic disturbance is an effective way to excite a separated shear layer and control the separation in the low Reynolds number region around Re = 500. In this study, the fundamental transient behavior of a burst wave-induced plasma actuator (BWPA) was investigated to control separated flow over a backward-facing step at low Reynolds numbers. The time-resolved induced velocity in quiescent air was measured using particle image velocimetry, and we found that the induced velocity exponentially grew and decayed independently of the burst frequency and duty ratio. For the flow over a backward-facing step, the reattachment process was drastically improved by BWPA operation when the oscillation frequency of the induced flow matched the acceptance frequency of the separated shear layer. We show the relations among BWPA operating parameters and the reattaching behavior of the separated flow.