In this paper, supersonic indicial pressure loads on a finite length planar surface (like those of an airfoil) subject to a strong crossflow, as caused by a gust or a sudden change of angle of attack, are studied. The unsteady pressure and force are obtained by an extension of linear theory, accounting for the nonlinear effects of shock waves on a windward surface and rarefaction waves on a leeward surface. Notably, the pressure in the nonuniform region (secondary wave) caused by interaction of the front and rear parts of the shock or rarefaction wave is assumed to be geometrically similar to that given by linear theory. The indicial force is expressed as an algebraic function of the edges of the secondary wave and pressure coefficients of uniform regions. The flow around a flat plate with a sudden change of angle of attack is used as a test case. By using a numerical simulation for comparison, it is shown that the modified theory increases the accuracy significantly at a large angle of attack, whereas the linear theory only works for very small angle of attack. When the constancy of the initial segment of the force curve, which is a phenomenon observed by numerical simulation, is used to correct the modified theory further, an extended model is obtained that is quantitatively correct, even for very a large angle of attack. The present nonlinear extension provides a clear and understandable description of the flow physics.


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    Title :

    Supersonic Indicial Response with Nonlinear Corrections by Shock and Rarefaction Waves


    Contributors:

    Published in:

    Publication date :

    2017




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English



    Classification :

    BKL:    55.50 Luftfahrzeugtechnik / 55.60 Raumfahrttechnik / 55.60 / 50.93 / 55.50 / 50.93 Weltraumforschung
    Local classification TIB:    770/7040