Radiative transfer and opacity calculations

Abstract

The similarity groups for multicomponent, reacting gas mixtures with radiative energy transport are derived. The resulting relations are used to consider the feasibility of scaling for flow processes with radiative energy transport under highly simplified conditions. Next the scaling parameters are derived for radiant energy emission from isobaric and isothermal gases for arbitrary opacities and various spectral line and molecular band models. The radiative scaling properties for representative temperature profiles for both collision-broadened and Doppler-broadened line profiles have been found for a spectral line belonging to a molecular vibration-rotational spectral band on the basis of exact numerical calculations. Representative calculations are also given for radiant energy transfer through non-isothermal, high-temperature air. Scaling parameters for radiant energy emission from isobaric but non-isothermal systems are discussed for arbitrary opacities and various spectral line and molecular band models under the restrictions imposed on the allowed temperature profiles for dispersion and Doppler lines by the Eddington-Barbier approximation. An examination is made of the failure of the Eddington-Barbier approximation in radiative heat transfer for line radiation. The relative importance of thermal conduction and radiation in heated air is specified through the use of the pertinent similarity group. Finally, a procedure is given that may be used to obtain approximate continuum opacity estimates in polyelectronic plasmas.