An experiment conducted in a pressurized, cryogenic wind tunnel demonstrates that unsteady flow control using oscillatory blowing (with essentially zero mass flux) can effectively delay flow separation and reattach separated flow on an airfoil at chord Reynolds numbers as high as 38 x 106. Oscillatory blowing at frequencies that generate one to three vortices over the controlled region at all times are effective over the entire Reynolds number range, in accordance with previous low-Reynolds-number tests. Stall is delayed and poststall characteristics are improved when oscillatory blowing is applied from the leading-edge region of the airfoil, whereas flap effectiveness is increased when control is applied at the flap shoulder. Similar gains in airfoil performance require steady blowing with a momentum coefficient that is two orders of magnitude greater. A detailed experimental and theoretical investigation was undertaken to characterize the oscillatory blowing disturbance, in the absence of external flow, and to estimate the oscillatory blowing momentum coefficient used in the cryogenic wind tunnel experiment. Possible approaches toward closed-loop active separation control are also presented. Based on the findings of the present investigation, the application of active separation control at incompressible flight Reynolds number is within reach.$


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    Title :

    Oscillatory control of separation at high Reynolds numbers


    Additional title:

    Steuerung der Strömungsablösung an Tragflächen bei hohen Reynoldszahlen durch periodisches Lufteinblasen


    Contributors:
    Seifert, A. (author) / Pack, L.G. (author)

    Published in:

    AIAA Journal ; 37 , 9 ; 1062-1071


    Publication date :

    1999


    Size :

    10 Seiten, 14 Bilder, 2 Tabellen, 21 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English






    Oscillatory Control of Separation at High Reynolds Numbers

    Seifert, A. / Pack, L. G. / AIAA | British Library Conference Proceedings | 1998



    Dynamics of active separation control at high Reynolds numbers

    Pack, LaTunia / Seifert, Avi | AIAA | 2000