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

Abstract

TitleComparison 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 nonpremixed turbulent jet flames are simulated using a comprehensive combustion solver. The combustion solver consists of a finitevolume/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 line-by-line (LBL) accurate Photon Monte Carlo (PMC) methods, with and without consideration of turbulence-radiation interaction (TRI). Various spectral models and RTE solvers are observed to have strong effects on peak flame temperature, total radiant heat source and NO emission. The P-1 method 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 the P-3 and the FVM with advanced k-distribution methods predict radiation more accurately than the P-1 method with any spectral model when compared to the benchmark LBL PMC. The LBL PMC yields exact results with sufficient number of samples and is found to be less expensive than the FVM (for all spectral models) and the P-3 (for some spectral models) in statistically stationary combustion simulations. 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).

Analysis of radiative transfer in a turbulent sooting jet flame using a Monte Carlo method coupled to large eddy simulation

“…Therefore, the soot subgrid models, accounting for the unresolved soot intermittency, could strongly affect the numerical predictions of TRI. Very few studies exist on soot subgrid models [42,25] The difference between profiles for gas-only radiative intensities indicates that turbulence-radiation interactions fairly increase mean radiative intensities in gas phase, as already observed in the literature [8,2,10,43,44]. Looking at the total radiative intensities that additionally account for soot particles, one can observe that the profile estimated from mean fields significantly overestimates the mean LES result in the sooting region.…”

“…In their study, the resolution of the radiative transfer equation (RTE) is based on the spherical harmonics method. Pal et al [10] have compared coupled RANS modeling of a turbulent jet sooting diffusion flame with spherical harmonics method, DOM method and Monte Carlo methods in terms of accuracy and cost. Again, an empirical model for soot particles was used in order to retrieve a good agreement with experimental measurements.…”

Soot and spectral radiation modeling for high-pressure turbulent spray flames

“…A hierarchy of spectral radiation models and radiative transfer equation (RTE) solvers has been implemented. 36 Here the statistical photon Monte Carlo (PMC) method with line-by-line (LBL) spectral resolution has been used. 37,38 in a post-processing mode.…”

A detailed modeling study of radiative heat transfer in a heavy-duty diesel engine

“…While DOM and variants probably have been used more widely than the others in combustion applications, recent work has shown that SHM methods (P1, P3, etc.) provide a more favorable tradeoff between computational effort and accuracy as one goes to higherorder implementations [34] .…”