酒精燃烧火焰的发射光谱研究

Study on Emission Spectrum of Alcohol Combustion Flame

利用光谱测量技术探测了酒精灯燃烧火焰(火焰高度20 mm)的发射光谱,并分析讨论了光谱强度的空间分布规律。发现酒精燃烧火焰光谱谱线对应三类粒子辐射:第一类为燃烧中间产物OH、CH和C_(2)自由基,其主要分布在火焰下部高度小于5 mm的范围内;第二类为C原子和C颗粒,其主要分布在火焰中部较小区域(10 mm~15 mm);第三类为H_(2)O和CO_(2)分子,其分布范围较广,在整个火焰高度范围内均有比较明显的光辐射,辐射强度峰值位于高度10mm处,在焰心附近和火焰中下部的外层辐射强度更大。结果表明,内焰(高度<5mm)主要发生酒精氧化链式基元反应的初期反应,生成中间产物自由基;焰心(高度10 mm~15 mm)及火焰外层主要发生链式基元反应的中末期反应,生成C原子和最终产物H_(2)O和CO_(2);外焰(高度>15mm及火焰外层)主要发生链式基元反应的末期反应,生成H_(2)O和CO_(2)。

The emission spectrum of alcohol lamp combustion flame(flame height 20 mm)was detected by spectral measurement technology,and the spatial distribution law of spectral intensity was analyzed and discussed.It is found that the spectral lines of alcohol combustion flame correspond to three types of particle radiation:the first type is the combustion intermediate OH,CH and C_(2) radicals,which are mainly distributed in the range of less than 5 mm high below the flame.The second type is C atoms and C particles,which are mainly distributed in the small area in the middle of the flame(10 mm~15 mm).The third category is H_(2)O and CO_(2) molecules,which are widely distributed.There is obvious light radiation in the whole flame height range.The peak radiation intensity is located at the height of 10 mm,and the outer radiation intensity near the center of the flame and in the middle and lower part of the flame is greater.The results showed that the inner flame(height<5 mm)mainly took place in the initial reaction of alcohol oxidation chain reaction,generating intermediate free radicals.The flame center(height 10 mm~15 mm)and the outer layer of the flame mainly take place in the middle and late stage of chain elementary reaction,generating C atoms and the final products H_(2)O and CO_(2).The outer flame(height>15 mm and the outer layer of the flame)mainly produces the final reaction of chain elementary reaction,generating H_(2)O and CO_(2).