Numerical analysis of radiative heat transfer in an aluminum distributed combustion region

The discrete-ordinate method was used to model the radiative heat transfer in an aluminum distributed combustion region resulting from the bunting of aluminized solid propellant. The participating medium in the aluminum distributed combustion region, which consisted of gas and particle phases, had nonhomogeneous, emitting, absorbing, and anisotropic scattering radiative properties. In this study, the contribution from soot and gas radiation was neglected, and a one-dimensional gray analysis was used to study the radiant heat transfer from burning aluminum droplets and condensed aluminum oxide particles. The coupling effect of the energy and radiative transfer equations was studied by the iteration method through the divergence of the radiative heat flux vector term in the energy equation. Results showed that the coupling effect between the energy and radiative transfer equations was not significant. The decoupled equations predicted the radiative heat feedback about 5% higher than that predicted by the coupled equations. Several factors, such as aluminum loading of the propellant, pressure, agglomerate size of aluminum droplets, emissive properties of burning aluminum droplets, and albedo of aluminum oxide, which affected the magnitude of the radiative heat feedback, were also examined.