同軸流拡散炎の火炎温度に及ぼすルイス数の影響

概要

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Lewis number and preferential diffusion effects on the flame temperature of coaxial-flow diffusion flames were examined. Flame analysis based on the flame sheet model shows that the flame is strengthened when Le_f>1 or Le_O<1 and weakened when Le_f<1 or Le_O>1, where Le_f and Le_O are the Lewis numbers of fuel and oxygen, respectively. This is caused by the increase or decrease in the total enthalpy in the flame due to the difference in diffusion rates between heat and reactants, and indicates that flame extinction at the flame tip (tip opening) might occur when the flame is weakened. It further shows that for a mixed fuel with two components having different Lewis numbers, Le_<f1> and Le_<f2>, component stratification by preferential diffusion occurs and mixed Lewis number effects become increasingly separated in the downstream direction. Therefore, in the case where Le_<f1>>1 and Le_<f2><1, preferential diffusion might bring about the minimum value in the flame temperature profile and lead to the local blow-off which was observed experimentally.
一般社団法人日本機械学会の論文
1995-06-25