Radiative Heat Transfer in a Counterflow Diffusion Flame Containing Reacting Metal Particles

The radiation effects are significant in amplifying the regression rate of a solid-fuel ramjet, especially when reacting metal particles or soot are present, or when the oxidizer mass flux is small. We study a simplified flame structure within the solid-fuel ramjet using a counterflow diffusion flame. The radiation transport equation is numerically solved using the spherical harmonics method. The radiation transport equation is coupled with a 1D axisymmetric counterflow solver within an open-source code, Cantera, using a source term in the energy equation. Validation cases are performed using different fuel types and good agreement with the experimental measurements are obtained. We analyse the effect of radiation from reacting metal particles on the flame profile and perform a parametric study by varying the particle diameters. The rate at which aluminum particles are injected from the fuel inlet depends on the fuel regression and the particle loading density within the fuel. The location and temperature of the particles are tracked using the Lagrangian equations of motion. A simplified model of combustion of aluminum particles is implemented using the D^2 law.