Local fine flame structure and its influence on mixing processes in turbulent premixed flames

Abstract Confined turbulent premixed flames stabilized by a pilot flame were investigated to elucidate the local fine structure of flames and its influence on mixing processes. The fine flame structure was classified on the basis of the measured turbulence characteristics, and the probability density functions (Pdfs) of local fluctuating velocity and temperature were examined in detail. A plateaulike distribution in temperature pdf, which may correspond to a “distributed reaction zone”, was observed in a limited portion of the flame in addition to a typical bimodal distribution corresponding to the structure of a “wrinkled laminar flame” or “laminar flamelets.” Using an inert gas tracer, we examine the influence of the fine flame structure on the mixing processes and discuss the retardation of mixing by the flame.