Flame dynamics in sub-millimetre combustors

Abstract

This paper describes experimental observations of flame dynamics within an alumina non-premixed combustor with a sub-millimetre (0.75 mm) minimum size. These flame dynamics occur within a total combustor volume of 130 mm 3 and are imaged through a sapphire window. The confined flames are surveyed using visual still-frames, high-speed flame imaging, measurement of external wall temperatures, and recordings of acoustic emissions from the combustor. The observed flame dynamics are characterised by an oscillating edge-flame that is anchored at the combustor inlet and is accompanied by ignition/extinction events leading to the eventual formation of a stable edgeflame and distinct cellular structures along the reaction channel. This paper investigates the unstable and unsteady flame dynamics within the nonpremixed sub-millimetre combustors from ignition to the formation of stable flame structures.

Operational regimes of rich methane and propane/oxygen flames in mesoscale non-adiabatic ducts

“…Jackson et al [16] developed a theoretical model capable of capturing flame oscillations of the type seen experimentally using a solely thermal model. Prakash et al [17] studied the dynamics and auditory emission of oscillatory phenomena of non-premixed methane-oxygen flames in rectangular alumina channels, and found that flame cells formed between the exhaust and an anchored edge flame. These flame cells were areas of rapid extinction and ignition events, rather than conventional oscillations.…”