Separation control of NACA0015 airfoil using plasma actuators with spanwise phase variations

Separation control of NACA0015 airfoil by means of plasma actuators was investigated. Plasma actuators in spanwise array on the suction surface of the airfoil were activated giving temporal periodic disturbances with spanwise phase variations φ = 0 or φ = π in the case of dimensionless burst frequency F⁺ = 6 and F⁺ = 0.5 at Re = 63000. The lift and drag of the airfoil were measured using a two-component force balance. The flow around the airfoil was measured by two-component PIV. In the condition of F⁺ = 6 and φ = π at stall angle, i.e. 10 degrees, the lift-to-drag ratio was higher than that of F⁺ = 6 and φ = 0, and the stall angle has extended by 2 degrees. In the most significant case, which is 12 degrees, lift coefficient in the case of F⁺ = 6 and φ = π improved by approximately 4.9% compared to the case of F⁺ = 6 and φ = 0. Therefore, it was confirmed that aerodynamic characteristics of the airfoil improved by temporal periodic disturbances with spanwise phase variations and it is expected that the improvement is attributed to the vortex structures, previously called “chain-link-fence structures”.