Turbulent jet diffusion flames: consolidation of flame height data

Literature data on flame heights of turbulent jet diffusion flames are examined in ratios to flame heights of purely buoyant turbulent diffusion flames. The flame height ratio is found to be a function of the gas release momentum in ratio to the momentum generated by a purely buoyant flame. It is constant near unity at low momentum ratios, begins to decay at momentum ratios exceeding 0.1, and attains a decay rate at higher momentum ratios consistent with constant flame height. The higher momentum-ratio range is the momentum regime, where flame-height to source-diameter ratios are found to depend on the source gas density, mass stoichiometric ratio, and heat of combustion of the source gas per unit mass of the ambient oxidizing atmosphere. Some large-scale literature data from outdoor experiments do not show good consistency with the other data. Comparisons of the present results with previous investigations reveal significant differences in modeling transitions to the momentum regime and flame heights within this regime.