Effects of Mainstream Velocity on Control of Backward Step Flow Using Plasma Actuators

Abstract

This study is concerned with the flow control of backward-facing step flow by a dielectric barrier discharge （DBD） plasma actuator. The DBD plasma actuator is mounted on the step edge, and the DBD plasma actuator is driven by burst modulation. Flow visualization behind the step and pressure measurement on the wall were carried out. As a result, when the mainstream velocity is changed, the burst modulation frequency that moves the reattachment point position most upstream or downstream changes, but the effect of the duty ratio on the reattachment point position does not change. In the case that the reattachment point moves upstream, the position where the vortex generated due to the instability of the shear layer changes depending on the off-time length of the plasma actuator which calculated from duty ratio and burst modulation frequency. When the duty ratio becomes larger than a certain value, the effect of control is reduced. And the effect of the length of this OFF time on the reattachment point position does not change even under conditions where the mainstream velocity is different.