掺混甲烷对乙烯层流预混火焰炭烟形貌的影响

摘要

Soot of ethylene laminar premixed flame mixed with methane was researched from the view of morphology.Ethylene laminar premixed flames and ethylene flames mixed with methane which had the same equivalent ratio (2.07),flame temperature and gas velocity were first produced.Three samples were sampled from each flame at different heights by TSPD,and then the distributions of soot diameters,mean diameters and mean equivalent spherical diameters of different soot samples were compared through the TEM and AFM analysis methods.It was noticed that low proportion of methane could make the soot size become large while more methane would led to the disappearance of this phenomenon.Through further calculation and analysis of the circularity,sphericity and fractal dimension,the very small particles were found to be not circular but fractal,which existed widely in different flames and different size of particles.Besides,the phenomenon was immune to the mixing ratio and the larger particles had looser shapes.%针对掺混甲烷的乙烯层流火焰中的炭烟颗粒从形貌角度进行了研究,构建了具有相同当量比(2.07)、火焰温度、气体流速的层流预混乙烯火焰和掺混甲烷的乙烯火焰,并各自选取了3个高度进行热泳探针取样,采用TEM和AFM方法对各个工况的炭烟颗粒粒径分布、平均粒径、平均体积当量球径进行了对比.发现少量的甲烷掺混会令乙烯火焰中炭烟颗粒的尺寸变大,而当甲烷掺混量变多时该现象消失.而通过对颗粒的圆度、球度和分形维数计算和分析,发现即使是很小的颗粒也具有相似的不规则形状,这一现象广泛存在于各种火焰和各种大小的颗粒中,不受掺混比的影响,并且越大的颗粒结构越松散.