中文摘要：

为探讨反应物预热温度和稀释率对稀释燃烧机理的影响，该文以氮气稀释的甲烷一空气对冲扩散火焰为研究对象，采用氢氧基平面激光诱导荧光法（hydroxy radical planar laser induced fluorescence，OH—PLIF）进行实验研究。以OH基反应区厚度表征火焰厚度，实验结果表明，在反应物预热温度较低情况下，当预热温度一定时火焰厚度随反应物稀释率增大（或者浓度减小）而减小，当反应物稀释率一定时火焰厚度随预热温度升高而增大。但进一步分析表明，在反应物预热温度足够高时，火焰厚度将随反应物稀释率增加而增大。根据预热对化学反应速度的增大与稀释对化学反应速度的减小的共同作用，从火焰厚度随反应物预热温度与稀释率的变化情况可推断，在低预热温度稀释燃烧过程中，预热温度是影响火焰结构的主要因素；在预热温度足够高的稀释燃烧过程中，稀释率是火焰结构的主要影响因素，此时由于稀释引起化学反应速度大大降低，因此火焰厚度或体积显著增大。

英文摘要：

In order to investigate the effects of preheat temperature and dilution rate of reactants on the dilution combustion mechanism, a laboratory-scale nitrogen diluted methane/air counter flow non-premixed flamed was studied using hydroxy radical planar laser induced fluorescence （OH-PLIF） method. Taking the reaction zone thickness of OH radical as flame thickness, it shows that flame thickness decreases with the increase of dilution rate at constant preheat temperature and increases with preheat temperature at fix dilution rate under the conditions examined in this experiment in which preheat temperature is not very high. However, further analysis of experiment results shows that flame thickness increases with the increase of dilution rate when the reactants are highly preheated. Moreover, according to the flame thickness variation condition and the collaboration of increasing effects of preheat temperature and decreasing effects of dilution rate on the chemical reaction rate, preheat temperature is regarded as the dominant factor under low preheated reactants diluted combustion condition but dilution rate is regarded as the dominant factor under highly preheated reactants diluted combustion in which dilution decrease the reaction rate and leads to the increase of flame thickness or flame volume.