Appearance of cool flame in flame spread over fuel droplets in microgravity

Appearance of cool flame in flame spread over fuel droplets in microgravity

This research conducted microgravity experiments to investigate phenomena appearing around a droplet existing outside the flame-spread limit. n-Decane droplets are tethered at intersections of SiC fibers. The flame spreads to two- or three-interactive droplets to heat a droplet placed outside the fl...

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Bibliographic Details
Published in:Proceedings of the Combustion Institute Vol. 39; no. 2; pp. 2449 - 2459
Main Authors: Mikami, Masato, Matsumoto, Kodai, Chikami, Yuto, Kikuchi, Masao, Dietrich, Daniel L.
Format: Journal Article
Language:English
Published: Elsevier Inc 2023
Subjects:
Cool flame
Droplet array
Flame spread
Microgravity
Flame spread
Droplet array
Microgravity
Cool flame
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Summary:This research conducted microgravity experiments to investigate phenomena appearing around a droplet existing outside the flame-spread limit. n-Decane droplets are tethered at intersections of SiC fibers. The flame spreads to two- or three-interactive droplets to heat a droplet placed outside the flame-spread limit of the interactive droplets. The cool-flame appearance during the flame spread over droplets was detected using different methods. The droplet diameter was measured with a back illumination to evaluate the vaporization-rate constant and to judge whether the cool flame appears or not. The temperature around the droplet was measured by the thin-filament pyrometry using a near-infrared camera to detect the temperature rise due to cool-flame appearance. The infrared radiation distribution from the combustion products was measured using a mid-wave infrared camera to judge the cool-flame appearance. The results show that a cool flame appears around the droplet existing outside the hot-flame-spread limit and the vaporization completes with the cool flame if the heat input from the hot flame is sufficiently large. This type of flame spread is called hot-to-cool flame spread. The definition of flame spread should be extended considering the cool flame.
ISSN:1540-7489
1873-2704
DOI:10.1016/j.proci.2022.07.053