Comparison of Accuracy and Computational Expense of Radiation Models in Simulation of Non-Premixed Turbulent Jet Flames

The accuracy and computational expense of various radiation models in the simulation of turbulent jet flames are compared. Both nonluminous and luminous methane-air non-premixed turbulent jet flames are simulated using a comprehensive combustion solver. The combustion solver consists of a finite-volume/probability density function-based flow–chemistry solver interfaced with a high-accuracy spectral radiation solver. Flame simulations were performed using various k-distribution-based spectral models and radiative transfer equation (RTE) solvers, such as P-1, P-3, finite volume/discrete ordinates method (FVM/DOM), and Photon Monte Carlo (PMC) methods, with/without the consideration of turbulence-radiation interaction (TRI). TRI is found to drop the peak temperature by close to 150 K for a luminous flame (optically thicker) and 25–100 K for a nonluminous flame (optically thinner). RTE solvers are observed to have stronger effects on peak flame temperature, total radiant heat source and NO emission than the spectral models. P-1 is found to be the computationally least expensive RTE solver and the FVM the most expensive for any spectral model. For optically thinner flames all radiation models yield excellent accuracy. For optically thicker flames P-3 and FVM predict radiation more accurately than the P-1 method when compared to the benchmark line-by-line (LBL) PMC.