The impact of thermal diffusion on the structure of non-premixed laminar flames

摘要

It is well understood how the flame structure of laminar non-premixed counterflow flames is influenced by differential diffusion, which is driven by species gradients, and corresponding models are available for physical and flamelet space. Thermal diffusion, driven by temperature gradients, is another process that leads to changes in the flame structure and can cause species separation due to differences in the thermal diffusion coefficients. In the present work, a systematic study quantifying the impact of thermal diffusion on the flame structure is carried out for many fuel-oxidizer mixtures. Exemplary flame structures are examined and compared to results obtained with an extended flamelet model accounting for thermal diffusion and non-unity Lewis number diffusion.