The spatial-temporal evolution process of flow field generated by a pulsed-DC plasma actuator in quiescent air

Flow control technology using the pulsed-DC plasma actuators has been demonstrated as an effective way of reducing the turbulent boundary-layer drag, which has attracted great interest from the aeronautical industry. However, the detail of the flow field induced by the pulsed-DC plasma actuator in quiescent air has rarely been addressed. In order to further reveal the controlling mechanism of the pulsed-DC plasma actuator, the experimental investigation on the flow field created by a pulsed-DC plasma actuator has been carried in quiescent air by using Schlieren visualization technique and Particle Image Velocimetry (PIV) measurement. In addition to the pressure wave induced by the pulsed-DC plasma actuator at the initiation stage, it is of great interest that two bi-direction vortices (vortex A and vortex B) and one corner vortex (vortex C) created by the pulsed-DC plasma actuator are observed and the tangential and vertical positions of the vortex core of the vortex A which is moving along the lower electrode are observed to scale with t^1/5 as it develops at 24.5 degrees to the wall. Meanwhile, the formation mechanisms of the three vortices are discussed. Based on the aforementioned results, the whole spatial-temporal evolution process of the induced flow field is summarized for affording a comprehensive detail of the pulsed-DC plasma actuator. The results lay a foundation for understanding the controlling mechanism and advancing the numerical simulation model of the pulsed-DC plasma actuator.