The effect of fuel composition and Reynolds number on soot formation processes in turbulent non-premixed toluene jet flames

The soot formation processes in three different turbulent prevaporized non-premixed toluene jet flames stabilized on a jet-in-hot-coflow (JHC) burner were investigated in this study. The jet Reynolds number and the stoichiometric mixture fraction were varied in order to manipulate the flow time scales and the chemistry, respectively. Time-resolved laser-induced incandescence (TiRe-LII), non-linear two-line atomic fluorescence of indium (nTLAF), and OH planar laser induced fluorescence (PLIF) were simultaneously applied to yield spatially resolved and instantaneous fields of soot volume fraction, primary particle size, temperature, and OH. The mean distributions of the detected quantities are used to identify major differences among the flames. The highest soot loading is observed for the low Reynolds number and low stoichiometric mixture fraction flame. However, this flame features also the lowest temperature and primary particle size. Based on these observations, the simultaneously detected data sets and flamelet computations are employed to elucidate differences in the soot formation pathways in the flames. The analyses reveal that the high soot loading causes greater heat losses in the low Reynolds number and low stoichiometric mixture fraction flame. This has a significant impact on the soot formation pathways and causes a reduction in the particle size. (c) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

The formation of soot in different turbulent jet flames is influenced by factors such as Reynolds number and stoichiometric mixture fraction. High soot loading leads to greater heat losses in flames with low Reynolds number and low stoichiometric mixture fraction, resulting in a reduction in particle size.