Characteristic Scales for Density Fluctuations in a Turbulent Premixed Flame

Light scattering from particles introduced into premixed flames, both open and confined, is used to distinguish between the predominant scalar states of unburnt mixture and fully burnt gas. Single-point time histories have been analysed to yield information on “packet” size distribution in the turbulent flame zone. Time duration for the respective scalar states is shown to be log normally distributed with substantial differences apparent between the most probable and average values. Characteristic features of open and confined burning emerge which suggest significant differences in turbulent flame structure.