Buoyant Turbulent Jets and Flames. 2. Refractive Index, Extinction and ScatteringProperties of Soot

摘要

Extinction and scattering properties at wavelengths of 250-5200 nm were studiedfor soot emitted from large buoyant turbulent diffusion flames where soot properties are independent of position in the overfire regionand characteristic flame residence time. Flames burning in still air andfueled with both gas (acetylene, ethylene, propane and propylene) and liquid (benzene, toluene, cyclohexane and n-heptane) hydrocarbon fuels were considered. Extinction and scattering measurements were interpretedto find soot optical properties using Rayleigh-Debye-Gans/ polydisperse-fractal aggregate (RDG/PFA) theory after establishing that this theory provided good predictions of scattering patterns and ratios of total scattering/absorption cross sections. Effects of fuel type on soot optical properties were comparable to experimental uncertainties. Measured depolarization ratioswere correlated with the primary particle size parameter, completing RDG/PFA methodology needed to make soot extinction and scattering predictions.