EFFECT OF SIGNAL MODULATION OF DBD PLASMA ACTUATOR ON FLOW CONTROL AROUND NACA 0015

Effects of DBD plasma actuator driven by six different type modulated signals on flow around NACA 0015 airfoil are experimentally investigated for lift augmentation. One actuator attached to the upside of the airfoil at x/c = 0.1 is used. Force measurement and smoke wire flow visualization are performed in a low speed wind tunnel. For Re= 3.6x10(4), the actuator is driven with six different signal modulations among which frequency modulation, amplitude modulation, excitation frequency and duty cycle at alpha = 10 degrees. SM4 including amplitude modulation is indicated to have better performance than the other signal modulations. Signal modulations provide energy savings while generating plasma to increase the lift coefficient. The obtained results indicate that as the dimensionless excitation frequency (r) is 1 at low duty cycle, a better lift coefficient is obtained in comparison with the other F+ values. For Re= 3x10(4), the lift coefficient is proportionally increased with driving voltage and frequency due to increasing induced flow at alpha = 10 degrees. Flow visualization results showed that the separated shear layer at the leading edge gets closer to the (suction) surface of the airfoil by increasing the driving voltage from 6 kV(pp) to 8 kV(pp) which confirms the driving voltage effect.