Soot aggregates, superaggregates and gel-like networks in laminar diffusion flames

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• 作者：Wongyo Kim ; Christopher M. Sorensen ; Danny Fry and Amitabha Chakrabarti
• 关键词：Flames ; Combustion ; Fractal aggregates ; Superaggregates ; Gelation
• 刊名：Journal of Aerosol Science
• 出版年：2006
• 出版时间：March 2006
• 年：2006
• 卷：37
• 期：3
• 页码：386-401
• 全文大小：641 K

文摘

We show that soot formed in laminar diffusion flames of heavily sooting fuels evolves through four distinct growth stages which give rise to four distinct aggregate fractal morphologies. Each successive stage grows upon the previous stage; hence aggregates of one morphology, parameterized by a fractal dimension, form larger superaggregates or gels of a different morphology with a different fractal dimension. These results were inferred from large and small angle static light scattering from the flames, microphotography of the flames, and analysis of soot sampled from the flames. These results and the analysis were substantiated by comparison to computer simulations. The growth stages occur approximately over four successive orders of magnitude in aggregate size. Each growth stage is a fundamental physical process: Stages 1 and 3 are diffusion limited cluster aggregation in three and two dimensions, respectively; Stages 2 and 4 are percolation in three and two dimension, respectively.