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.