Large-eddy simulation of correlation moments in turbulent combustion and validation of the RANS-SOM combustion model

The three-dimensional large-eddy simulation (LES) is carried out for a piloted methane-air jet flame (Flame C), measured in Sandia National Laboratory, and its statistical results are validated by experimental data. The LES statistically-averaged time-averaged temperature, the root mean square (RMS) value of temperature, and time-averaged methane and oxygen concentration are compared with those obtained using the Reynolds-averaged Navier-Stokes (RANS) equations with second-order moment (SOM) combustion model. Also, the cross-correlations in the time-averaged reaction rate expression of SOM model are given by the LES statistics. It is found that there is a similarity between the distribution of the correlation moments and the distribution of the products of corresponding averaged variable's gradients, the closure assumptions made in the algebraic second-order moment (ASOM) combustion model for RANS model is approximately valid.