FLOW QUALITY OF HYPERSONIC WIND-TUNNEL NOZZLES DESIGNED USING COMPUTATIONAL FLUID-DYNAMICS

A new methodology has been demonstrated for designing the aerodynamic contour of hypersonic wind-tunnel nozzles using a computational fluid dynamics based design and optimization procedure, The new design metho d was based on a least-squares parabolized Navier-Stokes design and op timization procedure developed by the first author, An optimization pr oblem was solved using the new design method to determine the aerodyna mic contour that minimized the flowfield Mach-number variation, Two ex isting wind-tunnel nozzles were remachined with the new aerodynamic co ntours designed with this procedure. The flow quality of the nozzles w as examined using detailed pitot-pressure profiles measured in the tes t section, The flow quality of the remachined nozzles showed an improv ement over a recently designed and constructed wind-tunnel nozzle base d on the classical method-of-characteristics boundary-layer correction technique, However, the how quality was not as uniform as predicted, because of disturbances emanating from mechanical joints. The pitot-pr essure profile away from the disturbance was extremely uniform, signif icantly better than for previous wind-tunnel nozzles at similar Mach n umbers, demonstrating the importance of using a computational-based de sign procedure for wind-tunnel nozzles that have to operate with thick boundary layers.