Browsing by Author "Weiss, Julien"

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    Experimental determination of the free stream disturbance field in the short duration supersonic wind tunnel of Stuttgart University
    (2002) Weiss, Julien; Wagner, Siegfried (Prof. Dr.-Ing)
    The present work investigates the free stream disturbance field in the Shock Wind Tunnel (SWK), a short duration supersonic facility of the “Institut für Aerodynamik und Gasdynamik” at Stuttgart University. It takes place in the framework of the Partial Project TPC5 from the Special Research Group 259 (SFB259), established at Stuttgart University and financed by the German Research Foundation (DFG). Measurements are performed at a nominal Mach number Ma=2.5 using a specially designed constant-temperature hot-wire anemometer (CTA) which enables an automatic scanning of the wire temperature in order to perform a complete modal analysis within one wind tunnel run (measurement time: 120ms). A new experimental procedure is developed to operate this anemometer in the SWK and, more generally, to extend the usual CTA operation in facilities with limited testing time. It is based on the post-processing of hot-wire results that are obtained with a non-optimized anemometer. In particular, a method enabling a very fast determination of the anemometer transfer function is developed. It is shown that the disturbance field is largely dominated by acoustic waves like in conventional supersonic facilities. The acoustic level is therefore repeatable from run to run, but depends on the position in the test section. Besides eddy Mach waves radiated by the turbulent boundary layer on the nozzle and the sidewalls, the disturbance field is characterized by highly localized shivering Mach waves caused by mean flow non-uniformities. Nevertheless, it is shown that due to its large size, its relative low disturbance character, and its economic mode of operation, the SWK should be remarkably advantageous for laminar-turbulent transition experiments.