Separation control on a NACA 0015 airfoil with plasma‑actuator-generated disturbance

This paper presents the experimental investigation on the flow control of a stalled airfoil at Re = 7.7×10⁴ based on the induced disturbance by the new dielectric barrier discharge DBD plasma actuator configuration. Unlike the traditional DBD plasma actuator with a uniform gap between the electrodes, the electrode gap of the new DBD plasma actuator (hereafter called sawtooth plasma actuator) changes periodically along the spanwise direction, and it is realized by arranging the two sawtooth electrodes with the opposite sawtooths pointing at each other. The sawtooth plasma actuator is found to induce streamwise flow and counter-rotating vortex pair at the tip and adjacent to the tip, respectively, in the absence of free air-stream. The application of the sawtooth plasma actuator on the NACA 0015 airfoil led to a delay in the stall angle-of-attack α by 51 and an increase in the maximum lift coefficient C_Lmax by about 9%. Under the same input power, the traditional straight-edged DBD plasma actuator managed a delay in stall α by 31 only and an increase in C_Lmax by about 3%. The mechanism responsible for the flow reattachment was examined and proved associated with the disturbance induced by the sawtooth plasma actuator.