The effect of exit Reynolds number on soot volume fraction in turbulent non-premixed jet flames

Soot volume fraction (SVF) was measured in five attached turbulent non-premixed jet flames of a C2H4-H-2-N-2 fuel mixture using the Laser-Induced Incandescence (LII) technique. The five flames comprise two sets with exit strain rates of 4100 and 7500 s(-1), respectively. Within each set, the exit Reynolds number was changed both by varying the jet diameter and the fuel exit velocity of the flames. Measurements of the mean, instantaneous and integrated SVF reveal a weak inverse dependence on the exit Reynolds number. A minor dependence of the axial and radial profiles of soot intermittency on the exit Reynolds number is also observed. The total soot yield is found to scale linearly with both the jet exit diameter and the fuel flow rate for the two flame sets of different exit strain. The total soot yield is also found to be a strong function of both the exit strain and the flame volume, but to be almost independent of the exit Reynolds number. A non-negligible effect of buoyancy on SVF is also deduced from the global correlations. (C) 2017 The Combustion Institute. Published by Elsevier Inc. All rights reserved.