Kinetic Modeling of Soot Formation in Turbulent Nonpremixed Flames

A coupled radiation/flamelet combustion model was applied to the simulation of two jet diffusion flames fed with ethylene and methane. The scope of this work was to demonstrate the application of several strategies for the solution of a two-equation model for describing formation of soot in turbulent non-premixed flames using simple semi-empirical models of soot nucleation, growth, oxidation, and coagulation. Three methods for closing soot production terms in turbulent flames are presented and compared. It is shown that turbulent fluctuations must be carefully taken into account to obtain a reliable prediction of soot volume fraction. Moreover, the coupling between the soot production rate and the radiative heat loss cannot be neglected. The predicted soot amount in the two turbulent flames investigated was relatively insensitive to the semi-empirical model adopted for nucleation. On the contrary, growth and oxidation models significantly influenced soot formation.