Abstract: 　The effects of water vapor on the adiabatic flame temperature, premixed flame temperature and laminar premixed flame velocity of methane combustion were studied by using Chemkin 17.0, and the effect of water vapor on the chain reaction process of methane combustion was also studied. The results show that with the increase of water vapor content, the temperature of methane flame and premixed laminar flame speed decrease, and the concentration of H,O,OH free radicals is also reduced, while the proportion of OH free radical is raised, leading to the dominance of reactions transmitted by OH free radicals. The addition of water vapor changes the chain reaction of methane combustion, enhances the reaction of CH3 to CH2(s),CH2(s) to CH2,CH2 to CH,CH to CH2O, and enhances the reaction of CH3 to CH3O,CH3O to CH2O at the same time.

Key words: Water vapor, Methane, Flame velocity, Free radical, Chain reaction

摘要： 为了研究水蒸气对于甲烷燃烧微观反应进程的影响，利用Chemkin 17.0研究了水蒸气对甲烷燃烧的绝热火焰温度、预混火焰温度和层流预混火焰燃烧速度的作用规律，研究了水蒸气对甲烷燃烧过程中链式反应进程的影响。结果表明，随着水蒸气摩尔分数的增加，甲烷燃烧火焰温度降低,预混火焰传播速度下降，且火焰中的H、O、OH自由基浓度均下降，但是OH自由基所占的比例增加，导致由OH自由基所传递的反应占主导地位。水蒸气的加入强化了CH3➝CH2（s）➝CH2➝CH➝CH2O过程，同时强化了CH3➝CH3O➝CH2O过程，改变了甲烷燃烧的链式反应。

关键词: 水蒸气, 甲烷, 燃烧速度, 自由基, 链式反应