Large-Eddy Simulation of the Sydney Swirling NonPremixed Flame and Validation of Several Subgrid-Scale Models

Abstract

A methane–air swirling diffusion flame is studied by large-eddy simulation (LES) using second-order moment (SOM) and simplified PDF subgrid-scale (SGS) combustion models, Smagorinsky-Lilly and dynamic kinetic energy (DKE) subgrid-scale (SGS) stress models. The predictions are validated by the experimental data. For LES statistics, comparison of the predicted axial and tangential time-averaged and root-mean-square (RMS) fluctuation velocities, temperature, RMS fluctuation temperature, CO₂ and H₂O mass fractions with the experimental results shows that all of the SGS models adopted here give results with only slight differences, but the DKE + SOM models are somewhat better than other SGS models. For instantaneous results, the predicted flame shape with a neck region is in agreement with that observed in experiments. The predicted flame shape and length obtained using the DKE + SOM models are better than those obtained using other SGS models. There are both large-scale and small-scale structures in the swirling flame; combustion reduces the large-scale structures and enhances the small-scale structures.

Acknowledgments

This study was supported by the National Natural Science Foundation of China under Grant 50606026 and the Youth Startup Funds of Shanghai Jiaotong University.