Assessment of engineering gas radiative property models in high pressure turbulent jet diffusion flames

Abstract

This article aims to determine the most relevant engineering global method for gas radiative property modeling to be applied in the simulations of combustion problems. Two versions of the full-spectrum correlated k (FSCK) model, the Rank-Correlated full-spectrum k-distribution/ Spectral-Line-Weighted-sum-of-gray-gases (RC-FSK/RC-SLW) and a new version of the Weighted-Sum-of-Grey-Gases (WSGG) model are compared with the Narrow-Band CK (NBCK) model in four turbulent axisymmetric jet diffusion flames fueled either by hydrogen or methane at atmospheric and higher pressures. These comparisons are performed in decoupled radiative heat transfer calculations with the thermal fields being prescribed. The databases and coefficients associated to these different models are determined from a unique Line-By-Line database in order to allow a relevant comparison. Model results suggest that the SLW/FSCK methods coupled to the so-called improved scheme proposed by Cai and Modest or the Rank-Correlated SLW/FSK model, along with k-g distributions generated from accurate high-resolution high-temperature databases are the most mature gas radiative property models to be implemented in CFD codes dealing with combustion problems involving gassoot mixtures.

Modeling Thermal Radiation in Combustion Environments: Progress and Challenges

“…Summary of spectral models. A review of the recent literature reveals that the FSK and SLW models are two of the most popular models for modeling nongray radiation in combustion environments [3,152]. In a recent article [149], it has been shown that the SLW and FSK models share many commonalities.…”

“…Although these two models are frontrunners, the WSGG model continues to be quite popular with its many recent improvements and updates, especially for coal combustion and other applications involving soot and/or high pressure [116,118,119]. Another model that has found some use is the narrow-bandbased k-distribution model or NBCK [152][153][154]. NBCK is computationally far more (>20×) expensive than either FSK or SLW, but has the best accuracy among all methods.…”

“…NBCK is computationally far more (>20×) expensive than either FSK or SLW, but has the best accuracy among all methods. Consequently, in recent studies of actual flames and fires, for which LBL calculations are all but impossible, NBCK results were used as benchmark results for assessing other models when two-way coupling with radiation is included [152]. Figure 8 shows a comparison of the accuracy of the latest versions of the FSCK, the rank-correlated SLW, and the WSGG models for the computation of the radiation source in a turbulent diffusion flame at two different pressures [152].…”

“…Consequently, in recent studies of actual flames and fires, for which LBL calculations are all but impossible, NBCK results were used as benchmark results for assessing other models when two-way coupling with radiation is included [152]. Figure 8 shows a comparison of the accuracy of the latest versions of the FSCK, the rank-correlated SLW, and the WSGG models for the computation of the radiation source in a turbulent diffusion flame at two different pressures [152]. The reference solution was computed using the NBCK model with 128 Gaussian quadrature points, and the errors are with respect to this reference solution.…”

Numerical solutions of radiative heat transfer in combustion systems using a parallel modified discrete ordinates method and several recent formulations of WSGG model

“…In past years, new developments of the model have relaxed some of its limitations, such as application to gas mixtures with varying molar concentration ratios and non-atmospheric pressures [17] and non-gray boundaries [18]. As shown in a recent study on coupled combustion calculations [19], in comparison with more advanced global gas model, such as SLW/FSCK, the model can provide comparable accuracy, even if not being the most accurate, with less computation time.…”