Optical properties in the visible of soot emitted from turbulent pool fires

The optical properties of soot at visible wavelengths (350-800 nm) were measured for soot emitted from liquid-fueled (benzene, toluene, cyclohexane and n-heptane) buoyant turbulent pool fires burning in air in the long residence time regime where soot properties are independent of position in the overfire region and residence time. The measurements were analyzed to find soot fractal dimensions, refractive index functions, refractive indices and dimensionless extinction coefficients, assuming Rayleigh-Debye-Gans scattering for populations of polydisperse mass fractal aggregates (RDG-PFA theory). The measurements yielded results that support recent findings for soot emitted from similar gas-fueled flames (acetylene, propylene, ethylene and propane): RDG-PFA theory is effective for estimating the optical properties of soot for the present range of conditions, soot fractal dimensions are independent of the fuel type and have a mean value of 1.79, soot refractive index properties are independent of the fuel type and are in reasonably good agreement with the often criticized measurements of Dalzell and Sarofim (1969), and dimensionless extinction coefficients are relatively independent of wavelength and fuel type over the present range of conditions and yield a mean value of 5.7, averaged over findings for both gaseous and liquid fuels.