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采用CHEMKIN的PREMIX模块对非常压下贫燃侧的一维、层流CH_4/Air预混火焰进行数值模拟,分析了不同的压力下辐射引起的最高火焰温度损失、主要反应的敏感性系数和主要自由基摩尔分数的变化。结果表明,辐射热损失随着当量比的下降而加强,在非单调变化的拐点附近,热辐射损失对最高火焰温度的相对变化作用明显加强。随着压力增大,近极限火焰的主要链终止反应H+O_2+M=HO_2+M的敏感性呈现先增大后减小的非单调变化,并逐渐被HO_2+CH_3=OH+C_3O取代;引起以上变化的原因是,随着压力增大,HO_2对其它主要基团(OH、O、H)的相对浓度明显增大。
CHEMIMIN’s PREMIX module is used to numerically simulate the one-dimensional, laminar CH_4 / Air pre-mixed flames at the lean side under very pressure. The maximum flame temperature loss caused by radiation under different pressures, the sensitivity coefficients of the main reactions, Free radical mole fraction changes. The results show that the radiative heat loss increases with the decrease of equivalence ratio, and the effect of heat radiation loss on the relative change of the maximum flame temperature is obviously strengthened near the inflection point. With the increase of pressure, the sensitivity of H + O 2 + M = HO 2 + M, which is the main chain termination reaction of near-limit flame, first increased and then decreased, then gradually changed into HO 2 + CH 3 = OH + C 3 O. The reason for the above changes is that the relative concentration of HO 2 to other major groups (OH, O, H) obviously increases with the increase of pressure.