Measurements of soot properties by means of laser-induced incandescence (LII) and combined scattering–extinction were performed in well-characterized premixed ethylene–air flames. In particular, the possibility of using LII as a tool for quantitative particle sizing was investigated. Particle sizes were evaluated from the temporal decay of the LII signal combined with heat balance modeling of laser-heated particles, and these sizes were compared with the particle sizes deduced from scattering–extinction measurements based on isotropic sphere theory. The correspondence was good early in the soot-formation process but less good at later stages, possibly because aggregation to clusters began to occur. A critical analysis has been made of how uncertainties in different parameters, both experimental and in the model, affect the evaluated particle sizes for LII. A sensitivity analysis of the LII model identified the ambient-flame temperature as a major source of uncertainty in the evaluated particle size, a conclusion that was supported by an analysis based on temporal LII profiles.
© 2000 Optical Society of America
Original Manuscript: September 24, 1999
Revised Manuscript: April 28, 2000
Published: July 20, 2000
Boman Axelsson, Robert Collin, and Per-Erik Bengtsson, "Laser-induced incandescence for soot particle size measurements in premixed flat flames," Appl. Opt. 39, 3683-3690 (2000)