Research On The Soot Precursors Growth Disipline In Premixed Laminar Ethylene Flame

Soot is one of the vital resources of atmospheric particle matter pollution produced from fossil fuels combustion. The soot formation mechanism from hydrocarbon fuel combustion becomes the focus in field of combustion research. Although HACA mechanism has been accepted widely, the details of soot nucleation and growth at high temperature has not been worked out clearly. In respect of soot formation mechanism, due to the lost of smaller size particle size distribution functions most mechanisms are not precise, which is the reason why smaller size particle should be studied. Particle size distribution can reflect the formation process of soot. Therefore, it is important for soot formation mechanism research to understand the particle distribution function from basic fuel combustion process.Therefore, this article put emphasis on detecting the PSDFs of soot particle coming from laminar premixed ethylene flame produced by planer burner using SMPS together with water cooling sampler techniques. Further research on factors what influence sampling qualities and PSDFs, such as shielding air flow rate, scanning time, stagnation temperature and dilution ratio, are tested to seek the optimal sampling conditions. Distance between sampler and burner was changed to get PSDFs at different height; change the flame temperature by changing the fuel flow rate without equivalence ratio change to learn about the influence on PSDFs.The main work includes:1. Shielding air flow rate should be greater than 10cm/s to protect flame from outside airflow oxidation. Long scanning time will cause sample loss, scanning time chose 50 second. The higher stagnation temperature, the less loss because of temperature difference. The optimal dilution ratio occurred between 189 and 333.2. According to the research on particle size distribution at different height, at first, soot nucleation dominated; then soot nucleation gradually weakened while the aggregation effects gradually increased, and the particle size distribution turned out to show two peaks; after that, aggregation effects dominated. Particle size distribution trend reflects the mutual competition between nucleation and aggregation effects.3. The higher flame temperature, the earlier appearance of soot nucleation, which refers to lower sampling height. As the flame temperature increasing, the knee point of bimodal distribution came earlier and moved towards small particle size direction.Through the experimental study in this paper on the above several aspects, scientific basis was provided for revealing the soot particle formation process and growth rules.