Measurement of Particulates in Flames by Laser Homodyne Technique

抄録

Local soot particle size in a flame is often measured by light scattering methods, which are hampered not only by low signal-to-noise ratio but also by a limited knowledge on refractive index. In the present study, a laser homodyne method was applied to determine the size and number density by detecting Brownian motions of particles. For processing the signal, a photoelectron correlation method was employed using a fast digital correlator. The particle size and the number density could be successfully determined by the correlation time and the count ratio of signal photocurrent pulse to total one, respectively. This method was applied to laminar diffusion flames on a Bunsen burner, and the spatial distributions of particle sizes and number densities were measured. A discussion is made of the possibility of detecting the polydispersity from the obtained correlogram.