Large Eddy Simulation of Methane Diffusion Flame: Comparison of Chemical Kinetics Mechanisms (original) (raw)

2010

Abstract

Large Eddy Simulations (LES) of the Sandia Flame D methane diffusion flame are carried out. An extended LES version of the Eddy Dissipation Concept (EDC) model is used as a turbulence combustion closure model. In LES the computational cost is high due to the fine grid resolution and unsteady nature of the governing equations. Using a detailed chemical mechanism in LES with EDC is too expensive, and hence, to reduce computational cost reduced mechanisms are preferred. In this study a number of PSR calculations for methane-air combustion using two reduced methane mechanisms and one detailed methane mechanism are carried out. The reduced mechanisms tend to strongly overpredict the temperature and major species mass fraction in either the lean or the rich mixture zone. Both mechanisms overpredict temperature for lean mixtures. The two reduced methane mechanisms are also studied with LES for the Sandia Flame D. The results of the two reduced mechanisms are compared with the fast chemistry approach and it is observed that in the lean mixture zone of the jet the reduced mechanisms overpredict the temperature and H2O mass fraction. Prediction with fast chemistry approach compared well with the experimental data. The present study emphasize the need of using fast chemistry approach instead of reduced mechanism when using the EDC combustion model.

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