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Methanol Droplet Extinction in Carbon-Dioxide-Enriched Environments in MicrogravityDiffusive extinction of methanol droplets with initial diameters between 1.25 mm and 1.72 mm, burning in a quiescent microgravity environment at one atmosphere pressure, was obtained experimentally for varying levels of ambient carbon-dioxide concentrations with a fixed oxygen concentration of 21% and a balance of nitrogen. These experiments serve as precursors to those which are beginning to be performed on the International Space Station and are motivated by the need to understand the effectiveness of carbon-dioxide as a fire suppressant in low-gravity environments. In these experiments, the flame standoff distance, droplet diameter, and flame radiation are measured as functions of time. The results show that the droplet extinction diameter depends on both the initial droplet diameter and the ambient concentration of carbon dioxide. Increasing the initial droplet diameter leads to an increased extinction diameter, while increasing the carbon-dioxide concentration leads to a slight decrease in the extinction diameter. These results are interpreted using a critical Damk hler number for extinction as predicted by an earlier theory, which is extended here to be applicable in the presence of effects of heat conduction along the droplet support fibers and of the volume occupied by the support beads
Document ID
20110020695
Document Type
Reprint (Version printed in journal)
Authors
Hicks, Michael C. (NASA Glenn Research Center Cleveland, OH, United States)
Nayagam, Vedha (National Center for Space Exploration Research on Fluids and Combustion Cleveland, OH, United States)
Williams, Forman A. (California Univ., San Diego La Jolla, CA, United States)
Date Acquired
August 25, 2013
Publication Date
June 4, 2010
Publication Information
Publication: Combustion and Flame
Volume: 157
ISSN: 0010-2180
Subject Category
Chemistry and Materials (General)
Report/Patent Number
E-17975
Funding Number(s)
WBS: WBS 904211.04.02.30.07
Distribution Limits
Public
Copyright
Other