2008 Volume 50 Issue 151 Pages 81-86
This paper theoretically discusses the stability of laminar jet diffusion microflame, defined as a flame established on a submillimeter-diameter burner. In addition to the ordinary liftoff/blowoff limits, insights into the lower extinction limit are of great practical importance for microflames; thus, this paper primarily focuses on the extinction limit of microflames. The applicability of the following two diffusion-flame models to microflames is first discussed: the Burke-Schumann (BS) theory and a self-similarity analysis. The BS theory is found to be suitable to study the stability of microflames. The extinction limit is then predicted using activation-energy asymptotics in the framework of the BS theory. The present theory qualitatively reproduces experimental observations, i.e., uL ∼ d-2, where uL is the jet velocity at the extinction limit (lower limit) and d the burner diameter.
