Structure and dynamics of kink and cellular flames stabilized on a rotating burner

Abstract

We describe the formation and evolution of spatiotemporal patterns in cylindrical premixed flames stabilized on a rotating cylindrical burner. We consider flames in the cellular regime, Le < 1, where the Lewis number Le is the ratio of thermal to mass diffusivity of a deficient component of the combustible mixture. For the parameter regime considered burner rotation tends to be stabilizing in that increasing the rotation rate generally promotes the development of traveling waves (TWs) from modulated traveling waves (MTWs). However, more complex dynamics occurs at the terminus of each of the TW branches. We find a number of unsteady, nonaxisymmetric modes of combustion, including (i) kink modes, where one or more kinks (characterized by a jump or discontinuity in the distance from the flame to the burner) rotate around the burner, (ii) cellular flames in which one or more cells rotate around the burner, (iii) Pacman modes, in which a rapidly rotating kink periodically overtakes and destroys more slowly rotating cells, with new cells created elsewhere, (iv) two front modes in which the flame, though governed by a 1-step reaction mechanism, exhibits two distinct regions of burning in a localized region of space, and (v) double fire rotating cellular flames (DF modes) which are MTWs where the modulation of each cell exhibits two maxima over each period such that one cell attains its first maximum simultaneously with the second maximum of its neighbor. Certain of the modes that we describe have not been previously observed for nonrotating burners either in experiment or in prior computation.