Numerical simulation of soot optical diagnostics in non-optically thin media

The global aim of this paper consists of quantifying the effect of optically thick media on LII measurements. The paper emphasises in a simple, general two-phase case, the potential “signal trapping” due to the multiple scattering of light by soot particles. A statistical Monte Carlo approach has been used in the frame of a parametric study. This method allows testing separately the distinct influences of parameters like soot volume fraction, sphere diameter, optical path length or aggregate shape. As a first result of this numerical study, the theoretical validity range of experimental techniques can be determined when applied to a larger domain than the strictly optically thin one. A numerical tool for a better understanding of mixed and complex phenomena has been realised. Here the approach is validated on the simplest geometrical configuration; it will be applied to a real combustion chamber configuration later. PACS 78.70.-g