Vortex-Flame Interaction of Spark-Ignited Flame with Coherent Structure in a Plane Shear Flow. Simultaneous Schlieren Observations of Front-and Side Views of a Propagating Flame.

Abstract

In order to elucidate the enhancement mechanisms of turbulent flame propagation, it is indispensable to examine and clarify the detailed process of vortex-flame interaction. This is because that it constitutes one of the key processes to promote flame propagation velocity. In this investigation a series of large scale organized eddies formed in the plane propane-air premixed shear flow are selected as an objective eddy-field. Two ingenious techniques are introduced and combined with each other ; one is the acoustic excitation of the shear layer, the other is the divided-double-beam high-speed schlieren photography. The former makes the organized eddy formation extremely regular and enables synchronized spark ignition with a single high-speed video camera, while the latter gives the chance to analyze two different directional views of a same propagating flame. In this paper a spark-ignited flame, which is initiated at the center of an organized eddy and propagates in the vortex tube, is optically observed and analyzed by using the proposed technique. According to the results, it is found that two kinds of effects of neighboring eddies on the enhancement processes of flame propagation.