氢气引燃的酒精超燃火焰结构分析

Analysis for flame structures of the alcohol supersonic combustion with hydrogen flame as pilot flame

关键词:  液体燃料  点火  超声速燃烧  火焰结构  稳定性分析

Key words:  Liquid fuel  Ignition  Supersonic combustion  Flame structure  Stability analysis

摘要:

为研究与液体酒精燃料超声速燃烧相关的点火和火焰稳定机理,利用氢氧基PLIF浓度分布测量技术,显示和对比了氢气引燃的酒精超燃火焰结构与氢气单独燃烧时的超燃火焰结构。通过对火焰着火位置、火焰主要结构特征的比较,分析了使用酒精和氢气时超燃点火与火焰稳定机理的差异。指出火焰结构的变化是由于燃烧控制机理发生了变化。研究发现,除了酒精化学性质不如氢气活泼带来的差别外,液体燃料的喷注、雾化和蒸发等都对火焰结构带来明显影响,其中蒸发过程对酒精火焰结构的形成起主要作用,组织液体燃料的超声速燃烧需要注意这样的差别;在所研究实验条件下,酒精主要由氢气点燃。

Abstract:

To investigate the mechanism of ignition and flame holding of supersonic combustion of alcohol, the flame structure of alcohol was imaged with OH PLIF. Images of OH distribution of alcohol combustion with hydrogen flame as pilot energy were also compared to the flame structure of hydrogen supersonic combustion flow. After making comparisons between ignition locations and between the main structure of flames, the difference of ignition and flame holding was analyzed. It is found that the change of flame structure is caused by change of control mechanism of combustion. Besides the change brought about by chemical property difference between alcohol and hydrogen, spraying, atomizing and evaporating of alcohol all pose obvious infection on flame structure. It is concluded that the evaporation of alcohol plays an important role in formation of the flame structure. Another conclusion is that the flame structure shows the alcohol is ignited by hydrogen flame.