Comparison of predictions with measurements for a quiet supersonic tunnel

Navier-Stokes and boundary layer calculations were made to study the mean flow through the Montana State University Mach 3 supersonic wind tunnel. Two-dimensional results along the nozzle surface are found to be in good agreement with experiment. For the sidewalls a 3D solution was necessary because of a skew-induced secondary flow that produced significant crossflows in the sidewall boundary layer and thickening of the boundary layer near the sidewall centerline. Boundary layer stability calculations revealed Goertler instabilities in the nozzle producing N factors up to 6. Preliminary results for the crossflow instability on the tunnel sidewall show a maximum N factor of about 2.5 under test conditions for which laminar flow was observed experimentally.