CHARACTERIZATION OF CARBON PARTICULATES IN-DIFFUSION FLAMES

A constrained multispectral transmittance method, where the optical pr operties of soot are assumed to be known, is used to determine in situ soot size distributions and volume fractions in six solid-, liquid- a nd gas-fueled diffusion flames. The resulting soot volume fractions ra nge from 0.97 x 10(-6) for propane to 1.1x10(-7) for acetone, and all soot size distributions indicate that the most probable radius is less than 0.1 mu m. In addition, it is found that in the visible region, t he relationship between the spectral extinction coefficient k(lambda) (cm(-1)) and the soot volume fraction f(upsilon) can be well represent ed by k(lambda)=(7.33x10(4) lambda(-0.989))f(upsilon), irrespective of the kind of soot. Here, lambda denotes the wavelength of radiation in units of mu m.