中文摘要：

采用实验研究的方法探讨了反应物预热温度与稀释率两个因素对稀释燃烧火焰稳定性的影响．实验以氮气稀释的甲烷-空气对冲扩散火焰为研究对象，确定了不同反应物预热温度与氧化剂稀释率（氧气体积分数）时火焰的熄火极限，结果表明，增大反应物预热温度拓宽了火焰稳定燃烧区域，而增加氧化剂稀释率（降低氧气体积分数）会降低稀释火焰的稳定性，二者对火焰稳定性的影响作用相反．为了进一步分析反应物预热温度与稀释率对火焰稳定性的影响程度，引入了估算的Damkohler数，分析表明，在实验研究范围内，反应物预热温度对火焰稳定性的影响比稀释率的影响显著，是火焰稳定性的主要影响因素．

英文摘要：

The effects of preheat temperature of reactants and dilution rate of oxidizer （ or oxygen concentration） on flame stability of diluted combustion, which was established in a （ CH4 ＋ N2 ）/（ Air ＋ N2 ） counter flow burner, were investigated in this paper. Flame stability was studied by determining extinction limits on various preheat temperature level and dilution rate. It was shown that stable combustion domain of flame was expanded with the increasing of preheat temperature, but high dilution rate of oxidizer decreased flame stability. Preheat temperature and dilution rate had opposite effects on flame stability characteristics. Extinction limit data analysis on the basis of an estimated Damkohler number showed that preheat temperature had a more important effect than dilution rate on flame stability, and therefore, it was the main factor of diluted combustion with flame under the conditions of the experiments examined.