Fuel Lewis number effects in unsteady Burke-Schumann hydrogen flames

    Authors

    M. Chaos; R. H. Chen; E. J. Welle;W. L. Roberts

    Comments

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    Abbreviated Journal Title

    Combust. Sci. Technol.

    Keywords

    unsteadiness; Lewis number; stretch; curvature; pulsation; diffusion; flame; NITRIC-OXIDE EMISSION; FINITE-RATE CHEMISTRY; PREFERENTIAL DIFFUSION; DYNAMICS; Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical

    Abstract

    Flame response (as determined by temperature and flame thickness) to unsteady hydrodynamics has been measured in acoustically pulsed Burke-Schumann hydrogen flames at two different oscillation frequencies and amplitudes. The effect of fuel Lewis number (Le(F)) on flame dynamics is isolated by investigating steady and unsteady 40% H-2/60% He (Le(F) > 1) and 40% H-2/60% Ar (Le(F) < 1) flames. For a given flame with Le(F) < 1, local temperature was found to increase with stretch imparted on the reaction zone by the unsteady flow, whereas the opposite trend was observed for the LeF > 1 flame. Unsteadiness might qualitatively alter the effect of the fuel Lewis number. Notably, for Le(F) < 1 flames under oscillations Of SUfficiently high frequency and amplitude, the temperature at the flame tip is higher than that in the shoulder regions, and is different from the temperature field of both steady and low-frequency oscillation flames. This suggests that the effect of unsteady flame stretch may overwhelm that of the flame curvature for sufficiently high unsteadiness.

    Journal Title

    Combustion Science and Technology

    Volume

    177

    Issue/Number

    1

    Publication Date

    1-1-2005

    Document Type

    Article

    Language

    English

    First Page

    75

    Last Page

    +

    WOS Identifier

    WOS:000226416300004

    ISSN

    0010-2202

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