ANALYSIS OF IN-SCATTERING EFFECTS ON LASER INDUCED INCANDESCENCE MEASUREMENTS THROUGH BACKWARDS MONTE CARLO

摘要

Laser-induced incandescence (LII) measurements carried out on aerosols having a large particle volume fraction must be corrected for extinction between the energized aerosol particles and the detector, called signal trapping. While standard correction techniques have been developed for signal trapping by absorption, signal trapping due to scattering requires further investigation, particularly the case of highly anisotropic scattering. This paper examines this effect in an aerosol containing highly-aggregated soot particles by simulating LII signals using a backwards Monte Carlo analysis; the signals are then used to recover a pyrometric beam temperature and soot volume fraction. The results show that in-scattered radiation is a substantial component of the LII signal under high soot loading conditions, which can strongly influence the properties derived from these measurements. Correction techniques based on Bourguer's law are shown to be effective in mitigating the effect of scatter on the LII signals.