天然气成分波动对其预混火焰传播特性的影响

利用定容燃烧弹试验平台和CHEMKIN PRO气相化学动力学软件，研究了常温常压和化学计量比下天然气成分变化对其层流燃烧速度和火焰不稳定性的影响规律。结果表明，天然气的层流燃烧速度随乙烷、丙烷和正丁烷含量的增加而上升，且乙烷的影响效果最为显著。天然气-空气火焰的不稳定性随着乙烷、丙烷和正丁烷含量的增加而降低，正丁烷对火焰综合不稳定性的抑制能力与丙烷相近，且都强于乙烷。火焰结构分析表明，天然气成分波动时H基浓度峰值的变化最为显著，天然气的层流燃烧速度与火焰中OH基和H基浓度之和的最大值之间有较强的相关性。层流燃烧速度敏感性分析和净反应速率分析表明，天然气成分变化会影响其燃烧过程中重要基元反应的进行，通过正影响的基元反应和负影响的基元反应之间的竞争，火焰中H基的浓度峰值发生变化，乙烷含量变化对H基浓度的影响最大。

Effects of component variation of natural gas on its premixed flame propagation characteristics

The constant-volume combustion vessel and CHEMKIN PRO software were employed to investigate the effect of component variation of natural gas on the laminar burning velocity and flame instability at the ambient temperature and pressure and stoichiometric ratio. The results show that the laminar burning velocity of natural gas rises with the increase of ethane content, propane content and n-butane content, and the effect of the variation of ethane content on the laminar burning velocity is the most obvious. The instabilities of natural gas-air flames are decreased with the increase of ethane content, propane content and n-butane content. For inhibiting the overall instabilities of natural gas-air flames, the ability of n-butane is approximately equal to the ability of propane, both of which are greater than that of ethane. The flame structure analysis shows that the variation of the peak value of mole fraction of the radical H is the most significant when the natural gas composition fluctuates. There is a strong correlation between the laminar burning velocity of natural gas and the maximum values of the sum of mole fractions of OH and H. The sensitivity analysis of the laminar burning velocity and the net reaction rate analysis show that the natural gas component variation affects the important elementary reactions. The competition between the elementary reactions with positive impacts and the ones with negative impacts varies the peak of H mole fraction and the variation of ethane content has the greatest effect on the mole fraction of H.