Large Eddy Simulation of the Sandia Flame E and F Using Dynamic Second-Order Moment Closure (DSMC) Model

Turbulent piloted methane/air diffusion flames (Sandia Flame E and F) are evaluated using dynamic second-order moment closure (DSMC) model. The DSMC model is a combustion model for large eddy simulation, which is assumed that the model could be applied to both premixed flames and non-premixed flames. And the density fluctuation is taken into account. In the model, the averaged reaction rate is directly closed in the form of Arrhenius law. The third-order fluctuation correlations are neglected, and the second-order fluctuation correlations are closed using the algebraic form. All the coefficients in the model are evaluated dynamically. The results from simulation have been compared with the available measurement data. In general, there is good agreement between present simulations and measurements both for Sandia flame E and F, which gives a reasonable indication on the accuracy and adequacy of the DSMC model. And the further application is considerable for the model. The sub-grid effects in this combustion model have been studied. The reaction rate of methane for flame E is higher than the value of flame F and the sub-gird reaction rate is in the reverse value of its filtered reaction rate with 25 %. The sub-gird effects play an important role in this combustion model and should be treated carefully.