Separation control on an airfoil under post-stall conditions by mechanical excitation

Abstract

The influence of mechanically generated perturbations upon the separated flow field on the suction side of an FX 61-184 airfoil under post-stall conditions (angle of attack α > 20°) has been investigated. As the flow separated immediately at the leading edge, an oscillating fence located just downstream of the separation line was used to introduce spanwise vorticity into the flow field. Resulting from the induced downwash motion of the vortices, a portion of the initially separated flow reattached, and the separation line moved downstream to a relative streamwise location of up to 15%. Thus, the suction peak in the pressure distribution was partly restored leading to a lift augmentation by as much as 40%.