Asymptotic analysis of radiation extinction of stretched premixed flames

The flammability limit, radiation extinction of stretched premixed flame an d effect of non-unity Lewis numbers are analyzed by the large-activation-en ergy asymptotic method. Particular attention is paid to the effect of Lewis number, the upstream and downstream radiation heat losses as well as the n on-linearity of radiation. Explicit expressions for the flame temperature, extinction limit and flammability limit are obtained. The C-shaped extincti on curve is reproduced. The dependence of radiation heat loss and the Lewis number effect on the stretch rate and flame separation distance is investi gated. The effects of fuel Lewis number, oxidizer Lewis number, upstream ra diation heat loss and the non-linearity of radiation on the C-shaped extinc tion curve are also examined. The results demonstrate a significant influen ce of these parameters on the radiation extinction and flammability limit a nd provide a good explanation to the experimental results and numerical sim ulations. (C) 1999 Elsevier Science Ltd. All rights reserved.