A stochastic combustion model for fire plumes

Abstract The paper presents a new model for turbulent mixing and combustion of fuel jets and buoyant plumes. It approximates the lateral distributions of velocity, density, and species concentrations with top-hat profiles. It calculates the downstream evolution of the mixture p.d.f. by use of a coalescence-dispersion concept. The model involves only two empirical turbulence coefficients: an entrainment coefficient and a mixing parameter. The relatively simple mixing model leads to integral solutions for the combustion rate, plume width, and flame radius versus downstream position. The model permits both fuel and oxidant to exist at each height with the combustion rate controlled by internal mixing. At this time the model has not been tested against experiment. It is also possible that detailed numerical evaluations of its predictions will lead to further simplification of approximations needed for engineering applications.