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Impact of the competition between aggregation and surface growth on the morphology of soot particles formed in an ethylene laminar premixed flame
Journal of Aerosol Science ( IF 4.5 ) Pub Date : 2021-02-01 , DOI: 10.1016/j.jaerosci.2020.105690
José Morán , Alexandre Poux , Jérôme Yon

Abstract Soot particle surface growth may have a significant impact on aggregation kinetics, particle morphology, and both aggregate and monomer size distributions. Particularly, the morphological effects of surface growth are currently poorly understood. This is complex since surface growth also affects the kinetics of aggregation resulting in a time-dependent competition between both phenomena, producing very different morphological markers. The present study aims at improving our understanding of the morphological impact of surface growth by implementing this effect in a Monte Carlo discrete element code for the simulation of soot formation in an ethylene premixed flame. An asymptotic average primary particle overlapping ∼ 30 % is observed for different flame conditions. The primary particle coordination number is highly sensitive to surface growth rate and particle volume fraction, and maximum values are on average within the 4 - 8 range. The particle local compacity, as quantified by the packing factor, is also considerably increased when aggregates experience surface growth, contrarily to the fractal structure of individual aggregates that seems more dependent on the aggregation regime. Finally, surface growth narrows both the primary particle and aggregate size distributions.

中文翻译:

聚集和表面生长之间的竞争对乙烯层流预混火焰中形成的烟尘颗粒形态的影响

摘要 烟尘颗粒表面生长可能对聚集动力学、颗粒形态以及聚集体和单体尺寸分布产生重大影响。特别是,目前对表面生长的形态影响知之甚少。这是复杂的,因为表面生长也会影响聚集的动力学,导致两种现象之间的时间依赖竞争,产生非常不同的形态标记。本研究旨在通过在 Monte Carlo 离散元代码中实现这种效应来提高我们对表面生长形态影响的理解,以模拟乙烯预混火焰中的烟灰形成。对于不同的火焰条件,观察到渐近平均初级粒子重叠约 30%。初级粒子配位数对表面生长速率和粒子体积分数高度敏感,最大值平均在 4 - 8 范围内。当聚集体经历表面生长时,由堆积因子量化的颗粒局部密度也显着增加,这与似乎更依赖于聚集状态的单个聚集体的分形结构相反。最后,表面生长使初级颗粒和聚集体尺寸分布变窄。与似乎更依赖于聚集机制的单个聚集体的分形结构相反。最后,表面生长使初级颗粒和聚集体尺寸分布变窄。与似乎更依赖于聚集机制的单个聚集体的分形结构相反。最后,表面生长使初级颗粒和聚集体尺寸分布变窄。
更新日期:2021-02-01
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