Experimental Study on Flow Control Using Non-Thermal Plasma (Pulsed Modulation Control Effect on Separation Flow)

Unsteady control effect of non-thermal plasma on leading edge separation flow was investigated experimentally. Wind tunnel experiment was done using a NACA0015 airfoil of 9 cm chord length of c under Reynolds number condition of Re=U∞c/ν=1.2×105, where U∞ : flow velocity, ν : kinematic viscosity. A pulse modulated mode with a fundamental frequency of 5 kHz was adapted to apply voltage to dielectric-barrier discharge electrodes which were mounted on the leading edge of the airfoil. First, effect of pulse modulation frequency on separation control was investigated. Second, effect of duty cycle was studied. Finally, FFT characteristic of wake flow under the separation control flow was discussed. An optimum frequency of f corresponds to fc/U∞=0.47 and 10% duty (discharge power of 0.18 W) was found to exist for unsteady excitation of the leading edge separation. FFT analysis result indicates that this optimum unsteady control of the dielectric-barrier discharge has a role to organize coherent structure of the separation flow.