Separation model for two-dimensional airfoils in transonic flow

Abstract : A calculation method for transonic separated flow about two-dimensional airfoils at incidence is presented in this report. The method is capable of predicting the effects of both leading- and trailing-edge separated flows, although the former is usually associated with a complete collapse of the airfoil flow field, in which case the flow is no longer supercritical. A viscous potential flow iteration procedure provides the connection between potential flow, boundary layer and wake modules. The separated wake is modelled in the potential flow analysis by thin sheets across which exists a jump in velocity potential. These sheets are analogous to vorticity sheets in incompressible flow. The basic potential flow method is a modification of Jameson's full potential method. Calculations for four different airfoils have been compared with experiment for pressure distributions as well as integrated forces. The agreement between theory and experiment is generally good even when shock waves are present. (Author)