The Transition to Instability in a Steady Hydrogen-Oxygen Diffusion Flame

Abstract

—Blow-off of a streamwise diffusion flame does not usually show features intermediate between those characteristic of the burner-attached flame and a quasi-stable lifted flame. The present work has, however, characterised an unusual intermediate stage in the blow-off of a lean hydrogen-oxygen diffusion flame, where the flame base takes on a stable cellular structure. From previous work, it is known that, near extinction, there is transfer of fuel through the base of the flame into the oxidant stream. The partial premixing resulting from such inter-stream transfer gives rise in the particular case of this lean flame to a composite premixed/diffusion flame structure at the flame base which is most probably responsible for the cellularity.