Abstract Three optical configurations of the LII technique: time-resolved, planar, and spectral, were used for a comparative analysis of soot topology, evolution and propensity in turbulent flames of Jet A-1 and Isopar-M. Selected configurations provide insights into particle size evolution, soot filaments topology, their probability of appearance, and soot volume fractions. Jet A-1 flame exhibits higher soot loads with longer decay times, indicating larger and more developed particles. In contrast, the Isopar flame shows weak soot signals with nearly constant decay times, suggesting limited particle growth. According to temporally averaged planar LII, significant differences are observed between both flames, in terms of intensity and spatial distribution. In the Isopar flame, apart from the lower observed signal, the spatial distribution is more homogeneous without a clear maximum, making it impossible to distinguish locations where soot formation or oxidation dominate. 2D LII soot filament intermittency is characterized using statistical image-to-image metrics to evaluate soot filaments topology between the two flames. Spectral measurements revealed the presence of interfering fluorescence and provided a means to infer the soot volume fraction in the Jet A-1 flame. These findings underscore the complexity of soot formation in spray flames and the need for multi-scale, time-resolved measurements to characterize these environments.
Gachot et al. (Mon,) studied this question.