Comparison between numerical and experimental data of the radiative heat transfer in a natural gas/CO2/H2 turbulent flame

Abstract

Accurate computation of the radiative heat flux emitted by turbulent flames involves the challenging modeling of turbulence-radiation interactions (TRI). This study considers a non-premixed turbulent flame, in which the fuel is natural gas with CO2/H2 dilution and ambient air as the oxidant. The radiative exchange is numerically solved using the weighted-sum-of-gray-gases (WSGG) gas model, and the discrete ordinates method for directional integration of the radiative transfer equation (RTE). The steady laminar diffusion flamelet (SLDF) model is used to solve the chemical kinetics. To account for the turbulence-chemistry interaction, the mean scalars are calculated by a presumed probability density function (PDF) approach. Turbulence is treated with the k-ε standard model. The impact of TRI modeling is performed employing two methodologies. The first one is based on the correlation between the absorption coefficient and the temperature self-correlation, considering that the absorption coefficient is only dependent on the mean local temperature. The second one considers the dependence of the absorption coefficient with both the mean temperature and the species mole concentrations. The temperature variance is obtained in two ways, using a transport equation and directly from the PDF approach. Five sets of numerical results are compared with measured experimental data for the radiative heat flux. The solution is obtained using ANSYS/Fluent code coupled with user-defined functions (UDFs) to compute RTE/WSGG/TRI formulations.