Soot and nanoparticle formation in laminar and turbulent flames

Fluorescence and incandescence measurements induced by the fifth harmonic of a Nd-YAG laser at 213nm are used for the determination of the volume fractions of particulate in a laminar premixed flame and in a turbulent non-premixed flame of ethylene/air. The light source selected enhances the fluorescence of Nanoparticle of Organic Carbon (NOC), which exhibit a large absorption band between 200 and 250nm, and also allows soot particles heating-up and incandescence emission. UV emission signals are correlated to NOC extinction coefficients, while LII signals are correlated to extinction coefficients in the visible region. Laser light scattering measurements are performed to estimate the mean sizes of both classes of particles. A new optical diagnostic method based on the interaction of a pulsed UV laser source with combustion-generated aerosols has been developed. It is able to characterize NOC and soot by point measurements.