Analysis of radiative transfer in body-fitted axisymmetric geometries with band models and anisotropic scattering

The problem of radiation heat transfer in divergent nozzles and diffusers is of real practical importance. The correct estimation of the radiative heating at the walls of these enclosures requires appropriate treatment of the spectrally dependent properties of the participating medium like absorption and scattering, along with a handle on high temperature gradients. The present study aims to apply the spectral line-based weighted sum of gray gases (SLW) model (Denison and Webb, 1993b) to body-fitted axisymmetric geometries like truncated cone-type enclosures, which resemble gradu-ally expanding diffusers, rocket exhaust nozzles, and typical industrial combustors that find wide engineering use. A modification of the discrete ordinates method (Baek and Kim, 1997b) has been employed to solve the radiative transfer equation. A mixture of three gases (viz. CO2, H2 O, and CO) has been considered and its spectral behavior is modeled using the SLW band model. Different particle loadings are incorporated and anisotropic scattering is modeled using transport approximation (Dombrovsky, 2012). A general purpose code, SLDOM (discrete ordinates method with SLW model), has been developed to handle these complexities of the problem. After a rigorous validation, a detailed analysis of the radiative heat fluxes at the curved wall is made under the influence of variable gas and particle concentrations with high temperature gradients. The results obtained show a strong dependence of radiative heat fluxes on particle concentration. Among gases, H2 O concentration was found more critical than other gases.