Direct measurements of the longitudinal variation of burning rate and product yield in turbulent diffusion flames

Abstract The paper reports on a new technique for making direct measurements of rates of production/depletion of major chemical species, as a function of height in intermediate-scale (up to 60 kW) jet and pool flames. Concentration measurements for O2, CO, CO2, H2O, and total hydrocarbons in the quenched flame gases are interpreted to yield heat release information. The data show good correlation between CO production and heat release for propane flames, while existence of a similar correlation for the radiant output appears possible, but will need to be confirmed by further work. A possible explanation of the observed trends is that the combustion process is characterized by two stages. Initial production of CO and soot is accompanied by release of energy, mostly in the convective field. During the second stage, more energy is emitted as radiation, while the intermediate products of combustion are being oxidized. A brief discussion is presented on the implications of the results concerning improvements of zone models of fire growth in enclosures.