Spatial growth of the spanwise disturbance induced by a synthetic jet on separation control over an airfoil

The spatial growth of the spanwise disturbance induced by a synthetic jet is investigated on separated-flow control around NACA0015 (Re=63; 000 and AOA = 12: 0°) using a large-eddy simulation. The synthetic jet is installed at a leading edge which is numerically modeled by a three-dimensional deforming cavity: “Cavity model”; and an artificial jet profile for a boundary condition: “Bc model”. The jet profile of the Bc model is assumed to be sinusoidally oscillated in a spanwise direction with a wave number from k_yin=2π = 0 to 95. In the Cavity model case, the modes around k_y=2π= 20 to 30 are selectively amplified near the synthetic jet, which remains also in the turbulent boundary layer. In the Bc model cases, the most quick turbulent transition occurs in the case with kyin=2π = 30, where the coherent spanwise mode strongly remains in the turbulent boundary layer although its aerodynamic performance is not best. This result indicates that in the present condition, the spanwise disturbance of the jet profile does not always contribute to the higher aerodynamic performance even if it provides smooth and quick turbulent transition.