煤粉射流火焰中碳烟浓度分布的LII测量

Laser Induced Incandescence Measurement of Soot Distribution in a Coal Jet Flame

基于Hencken型平面携带流反应器,使用激光诱导白炽光法(LII)测量煤粉火焰的碳烟浓度,并研究了激光能量密度F对测量的影响及火焰中碳烟的分布.研究发现,在F≤0.15,J/cm2时,煤颗粒信号相对较弱,碳烟信号占主导;在F>0.15,J/cm2时,煤颗粒信号干扰较强.F=0.05~0.08,J/cm2是最优能量密度范围.对本携带流实验系统,碳烟颗粒在距离出口80,mm处出现,且集中于中心中线4,mm范围内,碳烟浓度随着高度的增加先增加后降低,并在120,mm达到峰值.

The soot distribution in a coal jet flame was measured using laser induced incandescence （LII）technique based on a Hencken burner,and the effects of laser fluence（F）on soot measurement in coal flames were investigated. The results show that when F≤0.15 J/cm^2,the interference signal from coal particles is minor and the measured LII signal comes from soot particles. When F〉0.15,J/cm^2,the LII measurement of soot parti-cles is interfered by the LII signal of coal particles. The optimal laser fluence is found to be F=0.05-0.08,J/cm^2 in the present study. Soot particles start to appear at around 80,mm above the exit of the coal jet,and they are mainly formed within 4,mm near the centerline. The soot concentration along the centerline increases with h in the up-stream and then decreases in the downstream. The maximum soot concentration is found at h=120,mm.