Flame-flame interactions in lean premixed methane-air flames in a slot-jet configuration

Flame-flame interaction statistics are analysed for a series of lean methane-air flames in a slot jet configuration.  Direct Numerical Simulation (DNS) was used to simulate these flames, for which the turbulence integral length scale was systematically increased across the cases while keeping the Karlovitz number and the Kolmogorov scales constant. The Reynolds number Re, defined using the bulk velocity, slot width and the reactant properties, was ~ 22,000 for the case with the largest turbulence integral length scale. The frequency of flame-flame interactions is evaluated for the different cases, and also for the different regions within each flame. These regions are the flame base region, the fully developed turbulent flame region and the flame-tip region. The corresponding flame-flame interaction topology is also evaluated in these regions using the Morse theory of critical points. The differences in the results for the different regions, as well as across the dataset are compared and discussed. The findings of this analysis are used to explain the factors contributing to flame-flame interactions and their effect on overall flame propagation.