Study on Ignition-Like Behavior Induced by Interaction of Curved Non-Premixed (Diffusion) Flames

Abstract

An abrupt temperature increase induced by the interaction of “curved” diffusion flames is studied experimentally. The main purpose is to reproduce and measure the numerically predicted unsteady behavior of interacting flames experimentally. A pair of curved non-premixed (i.e., diffusion) flames, which was made by four slot burners (two combined counter flow burners), is utilized. Curved flames are either formed over the fuel stream (normal diffusion flame) or oxidizer stream (inverse diffusion flame) depending on the condition, and their interaction is demonstrated. The characteristics of the ignition-like behavior, namely, a time-sequential change in sound and luminescence from the image generated by the flame fluctuation, are acquired by a microphone and a high-speed camera, respectively. From the periodic unsteady behavior of interacting flames, the ignition-like behavior is successfully confirmed in the experiment. The observed change of frequency of the ignition-like behavior against the bulk velocity gradient agrees with that predicted previously in the numerical analysis.

Keywords:

• Diffusion flame
• Flame–flame interaction
• Ignition-like behavior
• Inverse diffusion flame

ACKNOWLEDGMENTS

This work is partially supported by a grant-in-aid for challenging exploratory research (NEXT, Japan, 2009–2010), the Tanikawa-Netsugijyutsu Foundation, and the Mazda Foundation. The authors express their sincere thanks for the support and contributions.

Notes

Published as part of the 23rd International Colloquium on the Dynamics of Explosions and Reactive Systems (ICDERS) Special Issue with Guest Editor Derek Dunn-Rankin.