Turbulent Premixed Flame Propagation Revisited Results with a New Model
Numerical simulations of the propagation of a one-dimensional turbulent flame in a premixed medium with constant density and given turbulence properties are presented. The key points of this academic problem are to propose realistic models for the mean reaction rate and for the turbulent flux which are of equal importance in this kind of problem. In the case of very fast chemistry, the mean reaction rate and the surface flame density are directly proportional to the dissipation rate of the progress variable c. The model proposed here for the mean reaction rate is based on the transport equation for the dissipation rate. Concerning the turbulent flux of c, the problem is treated in different ways. The transport equation for the correlation u c (for which a new modelling is proposed) is studied and is compared with the classical closure which consists of using a turbulent diffusion coefficient. The phenomenon of turbulent diffusion is also represented by random walks of fluid particles using a Monte Carlo simulation. The importance of the turbulent flux is principally evident in the transient period of the flame propagation and more on the “flame brush thickness” than on the propagation velocity. Comparisons of our simulation with experimental results concerning the turbulent flame velocity show a satisfying behaviour of the model.
KeywordsDissipation Rate Turbulent Flux Turbulent Flame Integral Length Scale Scalar Dissipation Rate
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