Investigation of Multicomponent Diffusion Calculation in Numerical Analysis of Diffusion Flames

In the numerical analysis of diffusion flames, multicomponent diffusion should be correctly evaluated, because various species with different diffusivities are generated in the process of combus-tion. In the evaluation of multicomponent diffusion, effective binary diffusivity is often adopted instead of exact multicomponent diffusion coefficient. For diffusion flames of H2 or H2 diluted with N2, the accuracy of calculation by effective binary diffusivity is investigated by comparison with that of exact multicomponent diffusion. In multicomponent system, diffusion of a species is generally driven not only by its own concentration gradient but also by that of the other species. The accuracy of calculation by effective binary diffusivity tends to be worse, when the influence of the concentration gradient of the other species is larger than that of its own concentration gradient.