Flow separation on a supercritical airfoil

Flow separation on the upper surface of the Bauer-Garabedian-Korn No. 1 supercritical airfoil was investigated in the National Aeronautical Establishment High Reynolds Number Two-Dimensional Test Facility. Detailed skin friction and pressures were measured to study the characteristics of separated flows. Fluctuating normal forces were determined for different types of transonic shock/boundary-layer interaction, and the behavior of the unsteady loads experienced by the airfoil was examined. For flow conditions where discrete frequency shock wave motions were detected, ensemble-averaging of the unsteady pressures was carried out to give the amplitudes and phases of the pressure waves generated by the shock. A model of the self-sustained periodic shock motion as a result of shock/boundary-layer interaction was proposed. Broad-band cross-correlations of the pressure field were carried out to determine the convection velocities of the turbulent eddies for attached and separated flows.