Numerical predictions of a turbulent diffusion flame in a cylindrical combustor using eddy dissipation and flamelet combustion models

A mathematical model has been applied to simulate a confined, turbulent nat ural gas diffusion flame for which measurements were reported in the litera ture [7]. The combustion is modelled using both eddy dissipation [2] and no n-equilibrium, mixedness-reactedness flamelet [6, 20] models. The latter mo del is based on a laminar flamelet approach originally developed for premix ed combustion. The turbulence is represented by a Reynolds stress model bas ed on the differential transport equations for stresses. The computational results are compared with experimental data for gas temperature and species concentrations. The predictions obtained using the flamelet model are foun d to be in good agreement with measurements, whereas the eddy dissipation c ombustion model fails to capture the measured trends in the near-burner reg ion. Efforts have been made to improve the quality of the predictions of th e latter model by incorporating an extinction criterion [25] and by adjusti ng the value of the model parameter. Both actions generate predictions simi lar to that of the flamelet model.