Full-spectrum k-distribution look-up table for nonhomogeneous gas–soot mixtures

Abstract

Full-spectrum k-distribution (FSK) look-up tables provide great accuracy combined with outstanding numerical efficiency for the evaluation of radiative transfer in nonhomogeneous gaseous media. However, previously published tables cannot be used for gas–soot mixtures that are found in most combustion scenarios since it is impossible to assemble k-distributions for a gas mixed with nongray absorbing particles from gas-only full-spectrum k-distributions. Consequently, a new FSK look-up table has been constructed by optimizing the previous table recently published by the authors and then adding one soot volume fraction to this optimized table. Two steps comprise the optimization scheme: (1) direct calculation of the nongray stretching factors (a-values) using the k-distributions (k-values) rather than tabulating them; (2) deletion of unnecessary mole fractions at many thermodynamic states. Results show that after optimization, the size of the new table is reduced from 5GB (including the k-values and the a-values for gases only) to 3.2GB (including the k-values for both gases and soot) while both accuracy and efficiency remain the same. Two scaled flames are used to validate the new table. It is shown that the new table gives results of excellent accuracy for those benchmark results together with cheap computational cost for both gas mixtures and gas–soot mixtures.