Abstract: In order to study the spectrum properties of the inverse methane/air diffusion flame，luminescent emissions from excited state radicals OH*(314nm) and CH*(430nm) have been measured in methane/air inverse diffusion flame emission spectrum by the fiber optical spectrometer. The effects of Reynolds number based on the cold-flow conditions of the air at the burner exit on the radiant intensity of OH* and CH*，and the distribution of radiant intensity along the flame axial and radial direction were analyzed. The results show that methane/air inverse diffusion flame has internal and external double-layer structure，the distribution of OH* and CH* radiant intensity along the flame axial and radial direction shows a trend of decrease after the first increase. With increasing rate of air flow，OH* and CH* extended to the flame downstream gradually，which made their distribution become larger. However，the peak intensity of the OH* and CH* appears at a distance of 5mm away from the burner exit，and the axial peak position does not change as the air flow increases.

Key words: Inverse diffusion flame；Spectrometer character；Emission；Experimental investigation

摘要： 为了研究层流甲烷反扩散火焰的光谱特性，采用光纤光谱仪对层流甲烷/空气反扩散火焰中发射谱线分别为314nm和430nm的激发态自由基OH*和CH*进行了光谱特性实验研究，分析了OH*，CH*辐射强度随空气喷嘴出口Re数的变化规律，及其沿反扩散火焰轴向与径向的分布特征。研究表明:甲烷反扩散火焰具有明显的内外双层结构，OH*和CH*辐射强度沿火焰轴向与径向均呈现先增后减的趋势。随着空气流量增大，OH*，CH*分布范围变大，并逐渐向火焰下游扩展。在距喷嘴出口5mm处出现OH*和CH*辐射强度峰值，且峰值的轴向位置不随空气流量增大而改变。

关键词: 反扩散火焰；光谱特性；辐射；实验研究