Nanosecond-Pulsed Dielectric Barrier Discharge Plasma Actuator for Airflow Control Along an NACA0015 Airfoil at High Reynolds Number

The goal of the present experimental study is to investigate the ability of a surface nanosecond pulsed dielectric barrier discharge plasma actuator, located at the leading edge of the airfoil, to delay flow separation along the suction side of an NACA0015 airfoil inclined at 13.5°, using a particle image velocimetry system. The free-stream velocity is equal to $U_{0}=40$ m/s, giving a chord-based Reynolds number of Re $_{c}=1.33 \times 10^{6}$ . At such conditions, the baseline flow separation occurs at about 50% of chord. On the one hand, the results show that the separation location moves progressively toward the trailing edge when the high-voltage frequency $F_{\mathrm {pulse}}$ is increased, up to 85% of chord at 1630 Hz (reduced frequency $F_{\mathrm {pulse}}^{+} = 10.6$ ), which is due to the increase of the injected electrical power with $F_{\mathrm {pulse}}$ (from 8 mW/cm at 40 Hz to 290 mW/cm at 1630 Hz). On the other hand, the use of a burst-modulated actuation (with a constant electrical power consumption equal to 145 mW/cm) does not produce the same behavior. At the lowest and highest frequencies (16 and 408 Hz, corresponding to the reduced frequencies of 0.1 and 2.65, respectively), the separation is delayed to about 60% of chord, while the most effective actuation is observed at $F_{\mathrm {burst}}= 80$ Hz ( $F_{\mathrm {burst}}^{+}=0.53$ ) with a separation delaying to 83% of chord.