Critical channel widths and flame front dynamics in curved premixed flames: Mach number dependence

This study numerically investigates the Mach number influence on the stability limits of stationary curved premixed flames. The numerical study is conducted over a range of realistic Mach numbers and varying channel widths. The results reveal that the stationary flame velocity increases with Mach number, consistent with prior studies. Notably, the study identifies two critical channel widths: (i) Dc, at which the Darrieus–Landau instability first occurs, and (ii) Dw, beyond which the flame velocity surpasses theoretical predictions based on weakly nonlinear analyses and the stationary curved flame velocity grows monotonically with increasing channel width. The second limit b=Dw/Dc is shown to decrease as the Mach number increases. Moreover, the transitions to the asymmetric flame front are observed for nearly isobaric Mach number in wide channels. It is investigated that with the decrease in the Mach number, the stationary curved flame velocity is closer to the analytical prediction.