Numerical study on soot formation in outwardly propagating, iso-octane, rich, cellular flames

Soot formation in outwardly propagating iso-octane rich unstable cellular flames were investigated by means of a two-dimensional numerical simulation at mixture equivalence ratios of 1.4, 1.6, and 1.8. The formation of a cellular flame structure was observed as an indicator of flame instability. In addition, soot formation was found to be enhanced. The cusp area had a negative flame stretch rate; in contrast, the convex area had a positive flame stretch rate. This difference in stretch rate caused a lower flame front temperature and lower temperature gradient. It was also revealed that a difference in temperature in these areas might affect the soot surface growth, which was dependent on the C₂H₂ concentration in these areas.