Assessment of weighted-sum-of-gray-gases models for gas-soot mixture in jet diffusion flames

Abstract

The global radiative property models are widely used in combustion simulation due to its high computational efficiency. This study assesses the weighted sum of gray gases (WSGG) models for gas-soot mixture in the simulations of turbulent jet diffusion flame at atmospheric pressure with fully coupled combustion and radiation heat transfer. Non-adiabatic tabulated chemistry approach and the method of moments were employed for combustion modeling and soot particle dynamics. The radiative transfer equations are solved by the discrete ordinate model. Two kinds of WSGG model based on mixture modeling (MM) and superposition method (SM), and their combination with the gray and non-gray soot radiative property models are involved in the comparison. First, the radiative property models are evaluated on the one-dimensional parallel plate system using line-by-line model as the benchmark, and then the WSGG models are evaluated on the basis of the FSCK model in the combustion simulation. The results show that MM and SM provide similar prediction accuracy, while MM has much lower computational cost. The MM combined with the non-gray soot radiative property model (MMNS) provides the best accuracy for gas-soot mixture. Moreover, the relative error of MM combined with gray soot radiative property model (MMGS) is less than 10% for radiation source term, which is acceptable in engineering simulation. The gray implementation of WSGG model has low accuracy, which indicates that it is necessary to use the non-gray implementation of WSGG model in CFD simulations.