Solid Fuel Combustion

Theoretical analyses were performed on several different types of diffusion flames to study the flame radiation effect. In the first problem, a soot formation and oxidation scheme was incorporated into a turbulent diffusion flame model adjacent to a solid fuel. The computed results for the natural convective fire showed good agreement with experimentally measured solid fuel burning rate. Soot radiation increased its importance with flame height. With flames greater than 1 meter, the radiative heat flux exceeded that by convection. In the second problem, matched asymptotic expansions were employed to study the spherical diffusion flame around a droplet or solid particle with flame radiation. It was found that the importance of radiation increased with droplet radius. The theory predicted that there was a maximum droplet or particle size above which a spherical flame could not be supported due to radiative loss. In the third problem, the thermophoretic motion of small particles e.g., soot were studied in a stagnation-point laminar flow next to a heated plate with and without combustion. It was found that both the thermophoretic motion and this Brownian particle diffusion can have a profound effect on the particle concentration distributions. js