A radiative model for the measurement of submicronic and micronic particles in flames by LII

The quantitative characterization of spray flames in terms of soot and larger particle emissions continues to be a major challenge in both fundamental investigations and practical applications. More particularly, a major interest can be found to discriminate inside the flame the two classes of particulate, namely soot and cenosphere, present in power generation plants fuelled with heavy fuel oils. The Time-Resolved Laser-Induced Incandescence (TIRE-LII) technique, widely employed for the determination of soot volume fraction and size in gaseous flames, can also be used in practical flames to discriminate the different particles, profiting from the size-dependent cooling behavior of these laser-heated particles. The TIRE-LII signals obtained in a heavy fuel oil spray flame were successfully fitted by a mathematical model including cenosphere and a new category of full particle called here "Pleosphere". It has been then possible to estimate the sizes of the different classes of carbonaceous particles and their relative contribution.