Visualization of Flame Front Propagating in a Constant-Volume Chamber

The present study aims to obtain a fundamental understanding of the mechanism of instabilities arising on a flame front propagating in a disk-shaped constant-volume chamber by visualizing the flame front with direct and Schlieren photography. For direct photography, a new operating system was used to get a instantaneous photograph with the shortest shutter speed 1/8000 sec. The ignition was performed at the center or at the point on the periphery of the chamber to see the effects of the wall configuration. The mixtures selected were methane-air and propane-air with various equivalence ratios. As a result, it is found that the photographs with a speed 1/4000 were satisfactory for visualizing flame shapes when the instabilities occurs on the flame front. Comparing with the Schlieren photograph, it is revealed that the flame itself wrinkles where the Schlieren image shows an anomalous shape.