丙烷扩散火焰中多环芳烃的激光诱导荧光测量研究

Detection of Polycyclic Aromatic Hydrocarbons in Diffusion Flame of Propane by Laser Induced Fluorescence

以丙烷-空气扩散火焰为研究对象,联合激光诱导荧光与激光诱导炽光,在不同探测波长下,对火焰中多环芳烃(PAH)的二维分布进行测量,分析火焰中PAH荧光信号的分布特征。结果表明:在丙烷扩散火焰燃烧中,小环PAH逐渐变为大环PAH,随后形成碳烟;通过测量火焰不同位置处的荧光时间分辨信号发现,在相同的条件下,荧光波长越大,其对应的PAH环数越多,相对分子质量越大,荧光衰减时间越长;随着火焰高度位置升高,荧光信号的衰减时间受温度升高的影响呈下降趋势。

This paper presents the spatial distribution characteristics of a polycyclic aromatic hydrocarbon(PAH)fluorescence signal in a propane-air diffusion flame and the variation of time-resolved signal with the flame height position.Results show that the PAH for smaller rings gradually shifts toward larger rings and then toward soot particles with an increase in the flame height position,which demonstrates the formation and growth process of PAH and soot in the combustion.Based on the measurement of time-resolved fluorescence,it is found that in the same environment,the measured fluorescence decay times of larger PAH are longer than those of small PAH for which fluorescence emissions are at shorter wavelengths.As the flame height position increases,the fluorescence decay time is observed to decline owing to the increasing temperature.