ON THE INFLUENCE OF A FUEL SIDE HEAT-LOSS (SOOT) LAYER ON A PLANAR DIFFUSION FLAME

A model of the response of a diffusion flame (DF) to an adjacent heat loss or ''soot'' layer on the fuel side is investigated. The thermal i nfluence of the ''soot'' or heat-loss layer on the DF occurs through t he enthalpy sink it creates. A sink distribution in mixture-fraction s pace is employed to examine possible DF extinction. It is found that ( i) the enthalpy sink (or ''soot'' layer) must touch the DF for radiati on-induced quenching to occur, and (ii) for fuel-rich conditions extin ction is possible only for a progressively narrower range of values of the characteristic heat-loss parameter, N(R)DELTAZ(R). Various interp retations of the model are discussed. An attempt is made to place this work into the context created by previous experimental and computatio nal studies.