Onset behavior of autoignited low-temperature flames caused by piston compression

Abstract

Compression-ignition processes of hydrocarbon/oxidizer mixtures are visualized using a combination of an image intensifier and a high-speed camera in wide range of temperatures. Onset images of cool-, blue- and final hot-flames are identified. Three typical regions of low-temperature ignition are classified and characterized. The cool flame onset followed by its degeneration is relatively homogeneous. Spatially nonuniform ignition is emphasized, though it does not always appear first in the vicinity of the cylinder wall as hitherto mentioned. Ignition in the blue flame dominant region, the highest temperature region of the low-temperature ignition, does not come under the category of the high-temperature thermal ignition usually obtained in shock tubes. © 1993, The Japan Society of Mechanical Engineers. All rights reserved.