AGGLOMERATE PARAMETERS AND FRACTAL DIMENSION OF SOOT USING LIGHT-SCATTERING - EFFECTS ON SURFACE GROWTH

Measured scattering, extinction coefficients, and dissymmetry ratios at 0.488-mu-m from a premixed propane-oxygen flame with a fuel equivalence ratio of phi-0 = 1.8 are combined with the scattering and extinction model for agglomerates to determine each of the following: primary particle diameter, number density of primary particles, and the total number of agglomerates as a function of position in the flame. The inferred primary particle diameters vary in the range from 0.009 to 0.029-mu-m whereas the fractal dimension of the agglomerate was estimated to be 1.7. In addition, both the Mie and agglomerate analysis of scattering and extinction data yield effective diameters that differ only by 1.8% or less for this type of flame system. However, the growth rates determined from the Mie scattering and extinction analysis are found to be higher by 106% or more when compared with the growth rates inferred from the agglomerate analysis.