Experimental Investigations of Separation and Reattachment Transient Flows Controlled by a Plasma Actuator*

This study presents experimental findings on the separation and reattachment transient flow phenomena over a NACA0015 airfoil wing utilizing a plasma actuator for flow control. The investigation examines flow behavior during the activation and deactivation of the control device, offering valuable insights for future feedback-based active flow control strategies, with the potential to enhance aerodynamic capabilities. The experiments were performed at a Reynolds number of 66,000 and an angle of attack of 13 degrees, representing leading-edge separation without control. The plasma actuator, operated at 8 kV voltage, 30 kHz base frequency, and burst frequencies ranging from 100 Hz to 600 Hz, was mounted on the wing's leading edge. The study employed particle image velocimetry to measure flow field velocities and eight piezoelectric pressure sensors to capture surface pressure data. The primary focus of this paper is on the first proper orthogonal decomposition mode of the transient flow velocity field, which is extensively analyzed and discussed. The results provide detailed insights into the flow separation and reattachment transient processes, including their flow structures and temporal evolution. One significant finding is the observed time asymmetry between the separation and reattachment transient processes, indicating potential opportunities to enhance actuator efficiency.