Test of flow separation control utilizing pulsed DC plasma actuation

Lift enhancement and drag reduction are critical objectives in aeronautics, focusing particularly on minimizing skin-friction drag at low angles of attack during cruise and suppressing flow separation at high angles of attack. Pulsed Direct Current Dielectric Barrier Discharge (pulsed DC DBD) plasma actuation emerges as a novel flow control technique. It achieves significant turbulent friction drag reduction with limited energy consumption, while offering ad-vantages such as simple system architecture, rapid response, and a wide frequency bandwidth. Targeting the control of airfoil flow separation at high angles of attack, an experimental investigation was conducted using the pulsed DC excitation method. Initially, comprehensive measurements of the discharge waveform, induced body force, and shock wave characteristics of the Pulsed-DC DBD were performed. Building on this, wind tunnel experiments were carried out on a straight wing model based on the NACA 0015 airfoil to investigate the influence of key parameters—including excitation voltage, pulse frequency, actuator placement, and free-stream velocity—on the effectiveness of flow separation control. Results indicate that the pulsed DC DBD simultaneously generates both a body force and a shock wave effect, which effectively suppresses flow separation at high angles of attack. This leads to a 7.17% increase in the maximum lift coefficient, a 2° extension of the stall angle, and a more gradual decline in the lift coefficient post-stall. Higher excitation voltages and lower free-stream velocities enhance the relative strength of the actuation compared to the flow field, resulting in improved control effectiveness. An optimal excitation frequency of 100 Hz was identified, which coincides with the shedding frequency of the separated shear layer and yields the best control performance. The actuator should be positioned at the leading edge to prevent its induced perturbations from being overwhelmed by the separation zone, thereby maximizing flow control effectiveness and achieving robust suppression of flow separation.