Accuracy evaluation of the gray gas radiation model in CFD simulation

AbstractGaseous combustion product, a mixture of radiating gas CO2, H2O and nonradiating gas N2, O2, absorbs and emits radiation spectrally selectively. Accurate simulation of radiation heat transfer inside a combustion chamber requires the line-by-line radiation model which is impossible for engineering practice because of the prohibitive computation time cost. The simplified gray gas model is the most popular model used in engineering CFD simulation. However, the accuracy of this model has not been systematically evaluated. Several radiation heat transfer cases have been simulated with the gray gas model and the simulation accuracy has been evaluated by the simulation result with the more accurate Statistical Narrow Band model. It is shown that the CFD simulation with the gray gas model can predict the peak heat transfer flux location accurately, but will over predict the heat flux and the heat transfer rate by as much as 23% for the tested cases