Conditionally sampled, ensemble-averaged velocity measurements, made with a laser velocimeter, were taken in the flowfield over the rear half of an 18 % thick circular arc airfoil at zero incidence tested at M = 0.76 and at a Reynolds number based on chord of 11 millions. Data for one cycle of periodic unsteady flow having a reduced frequency f of 0.49 are analyzed. A series of compression waves, which develop in the early stages of the cycle, strengthen and coalesce into a strong shock wave that moves toward the airfoil leading edge. A thick shear layer forms downstream of the shock wave. The kinetic energy and shear stresses increase dramatically, reach a maximum when dissipation and diffusion of the turbulence exceed production, and then decrease substantially. The response time of the turbulence to the changes brought about by the shock-wave passage upstream depends on the shock-wave strength and position in the boundary layer. The cycle completes itself when the shock wave passes the midchord, weakens, and the shear layer collapses. Remarkably good comparisons are found with computations that employ the time-dependent Reynolds averaged form of the Navier-Stokes equations using an algebraic eddy viscosity model, developed for steady flows. (DePo)


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    Title :

    Turbulence modeling for unsteady transonic flows


    Additional title:

    Modellierung der Turbulenz in einer instabilen transsonischen Stroemung


    Contributors:

    Published in:

    AIAA Journal ; 18 , 5 ; 489-496


    Publication date :

    1980


    Size :

    8 Seiten, 8 Bilder, 19 Quellen



    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English




    Turbulence Modeling for Unsteady Transonic Flows

    J. G. Marvin / L. L. Levy H. L. Seegmiller | AIAA | 1980


    On turbulence modeling for unsteady transonic flows

    MARVIN, J. / LEVY, JR., L. / SEEGMILLER, H. | AIAA | 1979



    Analysis of nonlinear transonic blockage in unsteady transonic flows

    Ferrand, P. / Smati, L. / Aubert, S. et al. | AIAA | 1997