Two-dimensional large eddy simulation of soot formation in the near-field of a strongly radiating nonpremixed acetylene-air turbulent jet flame

A numerical study of soot formation in the near-field of a strongly radiating, nonpremixed, acetylene-air planar jet flame is conducted using Large Eddy Simulation in two dimensions to examine coupled turbulence, soot chemistry, and radiation effects. The two-dimensional, Favre-filtered, compressible Navier-Stokes, total sensible energy and mixture fraction equations are closed using the Smagorinsky subgrid-scale (SGS) turbulence model. Major species of gas-phase combustion are obtained using a laminar flamelet model by employing experimentally obtained laminar flame state relationships for the major species mass fractions as a function of gas-phase mixture fraction. A combination of a presumed Beta filtered density function and a scale-similarity model are used to account for SGS mixture fraction and scalar dissipation fluctuations on the filtered composition and heat release rate. A soot transport and finite-rate kinetics model accounting for soot nucleation, surface growth, agglomeration, and oxidation is used. Radiation is modeled by integrating the filtered radiative transfer equation using the discrete ordinates method. Both instantaneous and time-averaged results are presented in order to highlight physical and numerical modeling issues and to examine turbulence, soot chemistry, and radiation interactions. Qualitative comparisons are made to previous numerical results and experimental data. (C) 1999 by The Combustion Institute.