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Earth, partial, and reduced gravity experiments and numerical work on propane-oxygen cool flames at sub-atmospheric pressures
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Earth, partial, and reduced gravity experiments and numerical work on propane-oxygen cool flames at sub-atmospheric pressures

Michael Robert Foster
Master of Science (M.S.), Drexel University
Sep 2006
DOI:
https://doi.org/10.17918/etd-1111
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Abstract

Cool flame Combustion
Natural convection plays an important role in nearly all terrestrial (1g), unstirred, static reactor cool flame and low-temperature auto-ignition studies. At near-zero gravity, however, Rayleigh numbers (Ra) less than the critical Ra for onset of buoyant convection can be achieved and the effects of convection can be suppressed. In this case, transport occurs strictly through diffusive fluxes of heat and species. To systematically vary the relative importance of natural convection versus diffusive transport without varying the mixture stoichiometry, reactor pressure, or vessel size, low-temperature reactions and cool flames are studied experimentally in a closed, unstirred, static reactor at 1g and aboard NASA's KC-135A subject to different gravitational accelerations (Martian-0.38g, Lunar-0.16g, and reduced-gravity-10⁻²g). Representative results will be presented on the visible light emission, the temperaturehistories, and the pressure histories at temperatures ranging from 593-623 K (320-350°C) in sub-atmospheric propane:oxygen premixtures. The results are compared qualitatively to numerical predictions derived from solutions to the coupled species, energy, and incompressible Navier-Stokes equations using a Gray-Yang skeletal kinetic mechanism.

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