Comparative Analysis of the Use of LES and RANS Approaches in 3D Numerical Simulation of Methane Combustion

Abstract

The paper presents the results of numerical simulation of methane combustion for LES and RANS approaches in CFD. CFD modeling was performed using the ANSYS Fluent software. Reynolds-averaged Navier-Stokes equations have been solved using the standard $\mathrm{k}-\varepsilon$ turbulence model. For the three-dimensional model of large vortices (LES, large eddy simulation), HPC calculations (high performance computing) are used. Simulation of the kinetics of methane-air premixed combustion was performed using the eddy dissipation model (EDC model) for the RANS approach and using the PDF model for the LES approach. To account for radiant heat transfer, the R-1 radiation model was used. An assessment of the possibility of using the vortex dissipation model according to the Damkohler number was made. The scientific substantiation and verification of the physical and mathematical approaches in ANSYS Fluent for the simulation of methane combustion was carried out. A numerical experiment was performed for a turbulent flow. It has been established that in the case of a turbulent flow, the nature of the temperature and velocity contours obtained using the LES and RANS approaches differ significantly. On the basis of a numerical experiment, it was found that the difference between the average temperatures of the combustion products is minimal in the area adjacent to the methane output. The maximum discrepancy of the average temperature is observed for the area of developed turbulence.