Flow control for an airfoil with leading-edge rotation: an experimental study

An experimental investigation has been conducted on a two-dimensional NACA 0024 airfoil equipped with a leading-edge rotating cylinder. The airfoil was tested for different values of leading-edge rotations and flap deflection angles. The effects of the angle of attack α, the cylinder surface velocity ratio U_c/U, and the flap deflection angle δ on lift and drag coefficients, the size of the separated flow region, and the stall angle of attack are included. The effect of U_c/U on the boundary-layer growth and turbulence intensity are also shown. Experimental results, for example, showed that the leading-edge rotating cylinder increases the lift coefficient of a NACA 0024 airfoil from 0.85 at U_c/U = 0 to 1.63 at U_c/U = 4 and delays the stall angle of attack by about 160%. Smoke-wire flow visualization results were also used to demonstrate the strong effect of the leading-edge rotating cylinder on the size of the recirculation region.