Observations of a Correlation Between Primary Particle and Aggregate Size for Soot Particles
Observations of a Correlation Between Primary Particle and Aggregate Size for Soot Particles
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DOI：
10.1080/02786826.2014.955565
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发表时间：
2014-01-01
影响因子：
5.2
通讯作者：
Rogak, Steven N.
中科院分区：
文献类型：
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作者：
Dastanpour, Ramin;Rogak, Steven N.
几十年来，烟灰一直被建模为近等轴球体的分形聚集体。簇-簇聚集模拟从初级粒子群开始，产生与火焰中产生的固体颗粒的真实气溶胶非常匹配的结构。在此类模拟中，初级颗粒尺寸与聚集体尺寸不相关，因为所有聚集体都包含来自同一群体的初级颗粒。气溶胶测量结果已用该几何模型进行了解释。对各种来源的烟灰样品的透射电子显微照片的检查表明，初级颗粒尺寸在气溶胶群体中没有很好地混合。较大的聚集体往往包含较大的初级颗粒，并且聚集体之间的尺寸变化比聚集体内部的尺寸变化大得多。这里考虑的烟灰源基本上都没有充分混合（飞机喷气发动机、反向扩散火焰、汽油直喷发动机、重型压燃式发动机）。如果在稀释和运输（以最小的凝结）到采样系统之前，在燃烧室的小区域中通过凝结形成并生长烟灰聚集体，则可以解释观察到的初级颗粒尺寸的变化。
For decades, soot has been modeled as fractal-like aggregates of nearly equiaxed spherules. Cluster-cluster aggregation simulations, starting from a population of primary particles, give rise to structures that closely match real aerosols of solid particles produced in flames. In such simulations, primary particle size is un-correlated with aggregate size, as all aggregates contain primary particles drawn from the same population. Aerosol measurements have been interpreted with this geometric model. Examination of transmission electron micrographs of soot samples from various sources shows that primary particle sizes are not well mixed within an aerosol population. Larger aggregates tend to contain larger primary particles and the variation in size is much larger between aggregates than within aggregates. The soot sources considered here are all substantially not well-mixed (aircraft jet engine, inverted diffusion flame, gasoline direct injection engine, heavy-duty compression ignition engine). The observed variations in primary particle size can be explained if soot aggregates are formed and grew by coagulation in small zones of the combustion chamber, prior to dilution and transport (with minimal coagulation) to the sampling system.