Premixed edge-flame oscillations in a rectangular channel with side-wall mass injection

Abstract

The steady structures and the dynamics of oscillatory motions of strained, premixed edge-flames are studied in a planar rectangular channel, closed at one end, with side-wall mass injection. The injection velocities are either constant or temperature-flux dependent. The motivation for this study is recent experiments conducted by Berghout et al (2000 Proc. Combust. Inst. 28 911–7) in a rectangular crack of a homogeneous propellant. The strained edge-flame dynamics are obtained by numerical solution of the zero-Mach-number, variable density Navier–Stokes equations, assuming a one-step reaction. Important parameters are found to be the Reynolds number Re based on the injection velocity and surface separation, the Lewis number Le, and the strain-dependent Damköhler number. We show the first theoretical illustration of edge-flame oscillations in a premixed environment, which are found to occur in near-limit conditions, induced, for example, by decreasing the mass injection surface separation distance leading to an increase in the characteristic strain rate, and for sufficiently large Lewis numbers. A marked difference between oscillatory edge-flame structures with constant and temperature-flux dependent injection conditions is also found.

M This article features multimedia enhancements available from the supplemental page in the online journal.