Oscillating flame in laminar helium-diluted coflow jets

Abstract

The unreported oscillation flame was discovered in helium-diluted coflow jet. It had a premixed-like structure when propagating toward upstream, and then again came back to be tribrachial flame in downstream. By the previous work [9], it was identified that it is under the augmented negative buoyancy, (ρf - ρco) by heavier fuel density than ambient coflow. But it was unable to be explained by buoyancy in that the generally known oscillating flame with a tribrachial structure also is influenced by the negative buoyancy. Thus, we focused on the characteristics of propagation as well as buoyancy to investigate the mechanism of the unreported oscillation flame.