Variation of pilot pressure was observed in a Mach 10 nozzle calibration test of the National Aerospace Laboratory 1.27m hypersonic wind tunnel immediately after a humid combustion gas evacuation system was added to the air heater. The mix of humidity provided by condensed water inside the tunnel structure was evaluation using run-by-run variations of evacuated heater pressure and of measured humidity level in the working air. The calibration data were also examined and a non-isentropic condensing flow through the nozzle was believed to have occurred. Thus modifications to prevent condensing of water were carried out and constant pitot pressure was obtained in a further calibration test. A statistical assessment was made of the data obtained before and after these modifications, and the results were compared to confirm the existence of a repeatable isentropic flow. This allowed efficient humidity management within the operation cycle. The water-effect free flow was assured by monitoring the humidity level and nozzle exit wall pressure.


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    Title :

    Technical Report of National Aerospace Laboratory Management for the NAL 1.27m Hypersonic Wind Tunnel


    Contributors:
    S. Nagai (author) / S. Tsuda (author) / T. Koyama (author) / N. Hirabayashi (author) / H. Sekine (author)

    Publication date :

    2001


    Size :

    18 pages


    Type of media :

    Report


    Type of material :

    No indication


    Language :

    English