Sliding discharge plasma jet actuators for circular-cylinder wake modification

Abstract

A sliding discharge (SD) plasma actuator designed for the control of a circular cylinder wake is examined experimentally in this paper. This kind of discharge demonstrates a thicker and higher maximum speed wall jet than a Dielectric Barrier Discharge (DBD). The plasma actuator mounted strategically on the rear part of the cylinder model can induce either a downward or upward jet into the flow around the circular cylinder by simply adjusting the electrodes’ electrical circuits. Experiments were performed in a low-speed and low-turbulence wind tunnel at Reynolds numbers between 7000 and 24,000 based on the diameter of the circular cylinder. Wake measurements by particle image velocimetry (PIV) showed that both the mean velocity and the turbulence level in the cylinder wake were modified under the plasma actuation. Reducing or increasing the cylinder drag force estimated from the velocity field could be realized by changing plasma actuation directions. They showed that up to 30% drag reduction and 24% drag increase were obtained with the downstream and upstream actuation respectively at the continuous plasma blowing. The efficiency of flow control was found to be about 1.8% for drag reduction. This study suggests that an appropriate arrangement of an SD actuator can practically suppress flow separation or enhance flow mixing.