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.