화학공학소재연구정보센터
Combustion and Flame, Vol.113, No.3, 454-469, 1998
A study of coupled turbulent mixing, soot chemistry, and radiation effects using the linear eddy model
Transient simulations of strongly radiating, acetylene-air, nonpremixed flames in stationary, homogeneous turbulence are conducted in order to study coupled turbulence, soot chemistry, and radiation interactions. The linear eddy model is used to simulate turbulent advection. A laminar flamelet state relationship combustion model is employed along with two different soot models. The first soot model involves an extension of the laminar flamelet concept to soot using a soot volume fraction state relationship. The second soot model involves transport equations for soot mass fraction and soot number density, which include finite rate source terms to account for soot nucleation, surface growth, agglomeration, and oxidation. Radiation effects are accounted for by including the appropriate source/sink terms in the conservation of energy equation. The effects of a presumed surrounding large scale field which radiates with the spectral properties of soot at an assumed effective temperature are also included. Simulations are conducted for two values of the surrounding temperature and the model large eddy turnover time. The results capture several unique aspects of strongly radiating turbulent flames. In particular, an inflection paint in the temperature versus mixture fraction profile is observed near the soot region which highlights the effects of radiative cooling. The large difference between radiation source terms calculated using mean properties and those calculated using instantaneous properties highlights the important interactions between turbulence and radiation.