The objective of the present paper is to investigate the flow characteristic in the vicinity of a plasma actuator and to obtain the separation control over a backward facing step by the plasma actuator experimentally. The plasma actuator is an electric device designed for flow control using electro hydrodynamic effect. By applying the pulse voltage signal at E=-5〜7kV and f_p=5kHz, the surface plasma is formed in the vicinity of the actuator. The Reynolds number based on tunnel height is set at 1600. The velocity near the actuator is greatly increased in one direction by the surface plasma, and the large-scale downward flow exists in the upstream region of the actuator. It was proven that the flow separation is greatly suppressed by applying the plasma actuator in the backward facing step flow.
