MEASUREMENT OF THE FRACTAL DIMENSIONS OF SMOKE AGGREGATES

A relationship relating aerodynamic diameter to volume equivalent diameter has been developed, which enables the fractal dimension of aerosol aggregates to be determined. The fractal dimension for carbonaceous smoke, under different formation conditions, ranged from 1.40 to 1.96, whilst for magnesium oxide smoke a figure of 1.08 was found. This is in agreement with observations based on scanning electron microscope examination, in which carbonaceous smoke clusters varied in degree of compaction and magnesium oxide smoke clusters were found to be chain-like. The results suggest that the fractal dimension is dependent on cluster material but independent of cluster size and show that smoke clusters forming under similar conditions have the same fractal dimension.