Predicting radiative heat fluxes from two buoyant turbulent diffusion flames from burning propane under cross wind

Abstract

Experimental investigations were carried out to estimate the radiative heating that occurs downstream of wind-driven buoyant turbulent diffusion flames produced by twin square propane burners aligned parallel to the cross wind. During the experiments, the heat release rate, cross wind velocity, and burner edge spacing were changed. Considering the effect of wind on flame shapes, a new triangular prism flame model was established to predict the radiant heat flux received by downstream objects from two buoyant turbulent diffusion flames under cross wind. The flame radiations to downstream ground were measured by five radiometers, and the relevant parameters of the flame model were analyzed. The results show that the radiative heat flux decays with increasing flame spacing and intensifies with increasing wind velocity. A piecewise function for the flame drag length in various flame merging stages is established. The effect of wind velocity and flame spacing on flame emissivity is relatively limited, and flame emissivity is formulated as a function of the heat release rate. The view factor between the triangular prism flame model and external targets is calculated based on the contour integral method. Finally, prediction results between the proposed triangular prism flame model and conventional models are compared against experimental data. The results confirm that the new triangular prism flame model can better predict the thermal radiation from two interacting flames in the wind.