Unified second-order moment model for turbulent combustion

A unified second-order moment model of turbulent combustion was proposed. The feature of this model is that all of the correlation terms, including the correlation of reaction-rate coefficient fluctuation with the concentration fluctuation, are closed by the transport equations in a unified form, accounting for the effect of chemical reaction on the dissipation of correlation. This model abandons the series expansion approximation of the exponential term or the approximation of using a product of two single-variable PDF instead of the joint PDF, made in other two versions of the second-order moment model. The proposed model was used to simulate methane-were jet combustion and the prediction results are compared with those using the EBU-Arrhenius model and other two versions of the second-order moment model. Validation of predictions using the experimental data given by the Sandia National Laboratory, USA indicates that the proposed model gives better results. The model is expected to simulate the detailed chemistry, while it is much economical than the complex PDF transport equation model or the conditional moment closure model.