Suppression of Tonal Trailing-Edge Noise From an Airfoil Using a Plasma Actuator

Suppression control of tonal noise generation at an airfoil trailing edge was conducted using a plasma actuator for a NACA0012 airfoil at a 2-deg angle of attack and at a Reynolds number 2.2 x 10(5) where the acoustic feedback responsible for the trailing-edge noise generation occurs in the pressure-side boundary layer. To minimize the possible interference of electrode installation in the boundary-layer stability a specially designed actuator with flush-mounted electrode configuration was employed. It was found that when the plasma actuator was installed at 55-60% chord location on the pressure surface a surface flow induced by the actuator stabilizes the downstream boundary-layer most significantly to suppress the strong growth of instability waves, which is responsible for the occurrence of the acoustic feedback. Consequently, suppression of the tonal trailing-edge noise was successfully achieved.