Modeling soot processes in a methane-fueled turbulent diffusion flame operating under atmospheric pressure

Soot processes in a turbulent methane diffusion flame for which experimental data are available in the literature, are simulated numerically. The soot generation model employed is the one of Syed et al. which was developed based on laminar methane flames under atmospheric pressure conditions, similar to the conditions of the experimental flame considered in this study. Different modeling conditions and case studies are considered. The effect of turbulence on soot processes is accounted for by means of source/sink terms added to the soot volume fraction and soot particle number density conservation equations; the two soot quantities solved for in the model of Syed et al. Turbulence closure of these source/sink terms is accomplished based on a simple presumed probability density function (PDF) for the temperature composed of two delta functions located at . The adopted combustion modeling is based on the eddy dissipation concept. Soot oxidation is represented by a combination of the Nagle and Strickland-Constable (NSC) formula and the eddy breakup model. Both of the standard version and the modified version of the k-ɛ turbulence model of Chen and Kim are used in the different cases studied. In addition, the effect of accounting for turbulence effects on soot processes is investigated. The comparison with the experimental soot results revealed that the case with best agreement with experiments is the one which accounts for turbulence effects on soot processes, and which uses a combination of the NSC and the eddy breakup model. Moreover, it is also found that the turbulence model employed strongly affects simulation results, where the modified version of the k-ɛ model proposed by Chen and Kim is found to enhance the quality of the obtained numerical results under the conditions of the present flame, significantly.