This study addresses the response of a swirling annular jet flow and flame to transverse acoustic excitation in order to better describe key velocity-coupled processes during transverse combustion instabilities in lean, premixed flames. In particular, visualization and velocimetry techniques provide information about the effects of acoustic excitation on unsteady vortex development in the shear layers. Without acoustic forcing, the shear layers roll up into small vortices, driven by the Kelvin-Helmholtz instability, that convect downstream and grow. In the presence of high-amplitude acoustic forcing, as would be present during a combustion instability, the acoustic oscillations drive shear layer vortices to undergo a strong rollup event. Smoke visualization provides visual evidence of the rollup, while particle image velocimetry measurements show the development and trajectory of this large structure. Finally, planar laser-induced fluorescence of OH shows how the large coherent structure causes flame wrinkling at the base of the flame. The vortex rollup, responding at the frequency of acoustic forcing, creates large-scale wrinkles on the flame and can be the main driver of flame response during combustion instability. Presented as Paper 2011-0237 at the 49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, Orlando, FL, 4-7 January 2011


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    Title :

    Visualization of Shear Layer Dynamics in a Transversely Forced Flow and Flame


    Contributors:

    Published in:

    Publication date :

    2015




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English



    Classification :

    BKL:    55.50 Luftfahrzeugtechnik / 55.50
    Local classification TIB:    770/7040




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