A new correlation between soot sheet width and soot volume fraction in turbulent non-premixed jet flames

Measurements of soot volume fraction (SVF) using planar Laser-Induced Incandescence (LII) were performed in a set of attached turbulent non-premixed jet flames, burning the same mixture of C 2 H 4 /H 2 /N 2 . A novel post processing technique was used to identify and characterize the average width (W s ) and volume fraction of the soot sheets and correlate it with key flame features and parameters. The axial distributions of both W s and SVF, within those sheets, in all flames are shown to grow with flame length up to the region where soot oxidation becomes significant, with only a secondary dependence on the inflow conditions. Probability density functions (pdfs) of W s are seen to exhibit far less variation than those of SVF, also indicating the soot structure morphology insensitivity to inflow conditions. The effects of fuel exit strain (U/D) and bulk exit Reynolds number (Re D ) on soot sheets are also assessed for three flames, of which two share the same U/D and two share the same Re D . The variation in U/D at constant Re D is seen to only affect SVF within the sheets, while a variation in Re D , at constant U/D is shown to have negligible effect on both Ws and SVF, in agreement with previous findings by the authors. Finally, a strong power-law correlation is deduced from joint statistics for W s and SVF through all flame locations and for all the flames investigated.