Electrical characteristics and flow topology of ring-type dielectric barrier discharge plasma actuator

This study is an experimental investigation on the electromechanical characteristics of a particular geometry arrangement of surface AC dielectric barrier discharge. Here, the geometry is composed of a central circular region bordered by the air-exposed electrode. This geometry referred as ring-type DBD has shown promising results regarding reduction in skin friction drag but the physics behind are of particular interest. Indeed, when the geometry is centimetric in size, the electromechanical conversion phenomena are identical to those observed for linear DBDs. The geometry favors the production of jets tangent to the dielectric surface which finally meet at a central point and end up forming a wall-normal jet. The original, and not expected, aspect is that when reducing the size of the system, the produced ionic jet is reversed and is now oriented towards the wall. Using a parametric study and experimental techniques to access the mean and unsteady quantities of the flow, the present study proposes to shed light on some aspects of this discharge caused by the reduction of its size.