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Fractal and Projected Structure Properties of Soot Aggregates.


pdf icon Fractal and Projected Structure Properties of Soot Aggregates. (1326 K)
Koylu, U. O.; Faeth, G. M.; Farias, T. L.; Carvalho, M. G.

Combustion and Flame, Vol. 100, No. 4, 621-633, March 1995.

Sponsor:

Naval Research Laboratory, Washington, DC

Keywords:

soot; aggregates; fractal properties; fractals; fractal properties; simulation; turbulent flames; laminar flames; equations; soot aggregates

Abstract:

The structure of soot aggregates was investigated, emphasizing the fractal properties as well as the relationships between the properties of actual and projected soot images. This information was developed by considering numerically simulated soot aggregates based on cluster-cluster aggregation as well as measured soot aggregates based on thermophoretic sampling and analysis by transmission electron microscopy (TEM) of soot for a variety of fuels (acetylene, propylene, ethylene, and propane) and both laminar and turbulent diffusion flame conditions. It was found that soot aggregate fractal properties are relatively independent of fuel type and flame condition, yielding a fractal dimension of 1.82 and a fractal prefactor of 8.5, with experimental uncertainities (95% confidence) of 0.08 and 0.5, respectively. Relationships between the actual and projected structure properties of soot, e.g., between the number of primary particles and the projected area and between the radius of gyration of an aggregate and its projected image, also are relatively independent of fuel type and flame condition.