Effects of suction on shock/boundary-layer interaction and shock-induced separation

Abstract

An experimental investigation of the effects of local boundary-layer suction on shock/boundar y-layer interaction and shock-induced separation has been conducted in the DFVLR 1 m x 1 m transonic wind tunnel utilizing an advanced transonic airfoil. Three different methods of suction were applied in the shock region. Their effectiveness in comparison to the basic closed-surface airfoil will be evaluated from surface pressure distribution, wake, and boundary-layer measurements. It will be shown that local boundary-layer suction in the shock region delays the development of shock-induced separation and considerably improves the overall aerodynamic characteristics. Moreover, two of the configurations investigated, viz., a double slot and a perforated strip with a cavity underneath showed, even without suction, a most favorable passive effect on shock/boundary-layer interaction and the overall flow development, thus offering a very promising means for extending the range of applicability of transonic airfoils.