Thermal Cracking and Variable Properties Effects on Free Boundary Layer Diffusion Flames

摘要

The paper presents an analytical model for a free convective boundary layer diffusion flame, and compares results from this model to experiment. The analytical model will add two new features to the solution presented by Pagni in order to improve agreement with experimental data. It is proposed that the fuel undergoes endothermic decomposition before reaching the flame. The endothermic decomposition of the fuel will be referred to as cracking. The effect of cracking on the free convective diffusion flame is explored by the use of modified Shvab Zeldovich variables which model both the flame reaction and the cracking reaction. The second addition to the solution given by Pagni is the use of a temperature dependent density-viscosity function which allows the ambient viscosity to be determined by ambient conditions. By using the temperature dependent density-viscosity function, the analytical model accurately predicts the location of the flame using the ambient value of viscosity.