Study on Formation Mechanisms and Control of NO_x in High Prssure Combustion

通过对一维层流火焰传播方程的数值求解，考虑了37种144种基本反应，利用理论计算的输运性质，研究了甲烷-空气预混火焰中NO的形成和提示。(1)通过对比有NO生成反应和无NO生成反应计算的NO浓度曲线，发现NO的生成主要受CH+N_2*HCN+N反应控制。(2)在0.6 ~ 1.4的任何等值比下，除等值比为1.4外，提示NO在可见火焰区域迅速形成，在下游区域不增加。在当量比为1.4的火焰中，仍在下游区域形成提示NO。(3)提示NO与总NO的浓度比在可见火焰区域较大，下游区域除当量比为1.4外，均迅速下降。(4)贫焰中未燃气体温度从298K增加到398K，提示NO的形成略有增加，富焰中没有变化。(5)在富焰中，随着压力从0.1MPa增加到0.2MPa，提示NO的形成增多。

The equations of one-dimensional laminar flame propagation were numerically resolved to study the formation of NO and prompt NO in the premixed methane-air flame by considering 37 species with 144 elementary reactions and by using theoretically calculated transport properties.(1) By comparing the concentration profiles of NO calculated with and without prompt NO formation reactions, the formation of prompt NO is found to be predominantly governed by the reaction CH+N_2*HCN+N.(2) At any equivalence ratio from 0.6 to 1.4, the prompt NO is rapidly formed in the visible flame region and does not increase in the downstream rgion except for the equivalence ratio of 1.4. In the flame of equivalence ratio of 1.4, the prompt NO is formed still in the downstream region.(3) The concentration ratio of the prompt NO to the total NO is large in the visible flame region and it deacreases rapidly in the downstream region except for the equivalence ratio of 1.4.(4) The formation of prompt NO increases slightly with the unburned gas temperature from 298K to 398K in the lean flame, but does not change in the rich flame.(5) The formation of prompt NO increases with the pressure from 0.1MPa to 0.2MPa in the rich flame.