Investigation of flow separation on a supercritical airfoil

Transonic shock/boundary-layer interaction on the upper surface of a supercritical airfoil was investigated in the National Aeronautical Establishment High Reynolds Number Two-Dimensional Test Facility. Skin-friction coefficient measurements on the airfoil surface were carried out using a Preston tube. At the lower Mach number range of the experiments, shock-induced and trailing-edge separation regions were found to exist simultaneously. Detailed experimental measurements were carried out at M = 0.688 and various values of a to investigate the merging of the two separated-flow regions. Steady and unsteady pressure measurements were made for various types of shock/boundary-layer interaction. Pressure power spectra were computed to study the characteristics of pressure fluctuations in the separated-flow regions. Fluctuating normal forces were measured for different types of flow separation, and the behavior of the unsteady load experienced by the airfoil was presented. Broadband cross-correlations of the pressure field were carried out to determine the convection velocities for attached and separated flows.