Sizing Soot and Micronic Carbonaceous Particle in Spray Flames Based on Time Resolved LII

A strategy for a comprehensive discrimination between soot and larger carbonaceous particles through numerical calculation was investigated in this paper, developing a particle diagnostic based on Time Resolved Laser-Induced Incandescence (TIRE-LII). TIRE-LII technique came out as a powerful tool profiting from the size-dependent cooling behavior of the laser-heated particles. Temporally theoretical LII signals were computed for different classes of particles considered in our investigations: soot, cenosphere and full carbonaceous sphere called by analogy “pleosphere”, pleo- from the Greek pleos, solid. These calculations were compared to the temporally resolved LII emissions obtained in a heavy fuel oil and in a diesel oil spray flames. Theoretical and experimental results showed a good agreement. It was evidenced that it was possible to fit the experimental LII profiles with the three kind of particles produced during heavy fuel and diesel oil combustion and their relative amount in terms of volume fraction. The particle sizes, successively estimated by mean of the developed theoretical model, were reasonable and consistent with the particle size distribution measured by sampling.