Combustion characteristics and liquid-phase visualisation of single isolated diesel droplet with surface contaminated by soot particles
Combustion characteristics and liquid-phase visualisation of single isolated diesel droplet with surface contaminated by soot particles
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DOI：
10.1016/j.proci.2018.08.023
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发表时间：
2019-01-01
影响因子：
3.4
通讯作者：
Zhang, Yang
中科院分区：
文献类型：
--
作者：
Rasid, Ahmad Fuad Abdul;Zhang, Yang
首次通过实验研究了燃烧产生的烟尘污染对单个柴油液滴点火和燃烧的影响。在点燃之前，使用柴油液滴火焰来污染待研究的液滴。在加热、沸腾和破坏阶段，观察到纯液滴样品和污染液滴样品的燃烧寿命和稳定性存在明显差异。对于被烟灰污染的液滴表面，由于传质较慢，蒸发速率变弱，从而收缩了火焰的形成。与其他研究人员观察到的稳定且均匀的颗粒悬浮液液滴燃烧速率提高相反，燃料液滴表面中最轻微的烟灰颗粒污染就会显着降低燃烧速率。更密集的烟灰团聚可以在液滴表面形成壳，该壳阻止气体通过表面逸出，从而使液滴进一步变形。在燃烧后期，观察到气泡在受烟灰污染的液滴表面破裂。观察到挥发性液体和蒸气的强烈喷射，这些液体和蒸气在与液滴分离后不久就会爆炸。喷射混合物的爆炸和燃烧似乎与初级液滴周围的包络火焰几乎没有相互作用。液滴液相的增强可视化清楚地表明了受碳烟污染的柴油液滴的燃烧速率和火焰隔离比下降趋势的原因。这些见解对于理解燃烧产生的烟灰颗粒对燃料滴污染的影响具有重要意义。 (C) 2018 年燃烧研究所。由爱思唯尔公司出版。保留所有权利。
The combustion generated soot contamination effect on a single diesel droplet ignition and burning was investigated experimentally for the first time. Diesel droplet flame was used to contaminate the droplet to be investigated prior to ignition. Distinct differences in lifetime and stability of the burning of the neat and contaminated droplet samples were observed in their heating, boiling and disruptive phases. For a soot-contaminated droplet surface, the evaporation rate became weaker as a result of slower mass transfer thus contracted the flame formation. Contrary to the burning rate enhancement of droplet with stable and uniform suspension of particles observed by other researchers, the slightest contamination of soot particles in a fuel droplet surface can significantly reduce the burning rate. Denser agglomeration of soot can form a shell on the droplet surface which blocks the flow of gas escaping through the surface thus distort the droplet even further. At late combustion stage, bubbles are observed to rapture on the surface of the soot-contaminated droplet. Strong ejections of volatile liquid and vapour that would explode shortly after parting from the droplet are observed. It seems that the explosion and burning of ejected mixture have little interactions with the enveloped flame surrounding the primary droplet. Enhanced visualisation of droplet liquid-phase has clearly indicated the cause of declining trend in the burning rate and flame stand-off ratio of soot-contaminated diesel droplet. These insights are of significance for understanding the effect of fuel droplet contamination by combustion generated soot particles. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.