Application of full-spectrum k-distribution method to combined non-gray radiation and forced convection flow in a duct with an expansion

Abstract

This paper presents a numerical analysis of interaction between non-gray radiation and laminar forced convection flow in a duct with an expansion. Distributions of absorption coefficients across the spectrum (50 cm −1 < η < 20000 cm −1) are obtained from the HITRAN2008 database. The full spectrum k-distribution method (FSK) is used to deal with the non-gray part of the problem, while the gray radiation calculations are carried out using the Planck mean absorption coefficient. In addition, the results of non-gray medium are compared with the gray results in order to judge if the differences between these two approaches are significant enough to justify the usage of non-gray models. Results show that for air mixtures with different mole fractions of CO2 and H2O, use of gray model for the radiative properties may leads to considerable errors and should be eschewed.