Unsteady Diffusion Flames: Ignition, Travel, and Burnout (SUBCORE Project: Simplified Unsteady Burning of Contained Reactants)

TITLE AND SUBTITLE:
Unsteady Diffusion Flames: Ignition, Travel, and Burnout (SUBCORE Project: Simplified Unsteady Burning of Contained Reactants)

AUTHOR(S):
Francis Fendell and Harald Rungaldier

REPORT DATE:
February 1999

FUNDING NUMBERS:
WU-963-15-0G-00
NAS3-27264

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
Electro-Optics, Lasers and Research Center
TRW Space and Electronics Group
One Space Park
Redondo Beach, California 90278

PERFORMING ORGANIZATION REPORT NUMBER:
E-11466

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135-3191

REPORT TYPE AND DATES COVERED:
Final Contractor Report

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA CR-1999-208686

SUPPLEMENTARY NOTES:
Project Scientist, Suleyman Gokoglu, NASA Lewis Research Center, organization code 6711, (216) 433-5499.

ABSTRACT:
An experimental apparatus for the examination of a planar, virtually strain-rate-free diffusion flame in microgravity has been designed and fabricated. Such a diffusion flame is characterized by relatively large spatial scale and high symmetry (to facilitate probing), and by relatively long fluid-residence time (to facilitate investigation of rates associated with sooting phenomena). Within the squat rectangular apparatus, with impervious, noncatalytic isothermal walls of stainless steel, a thin metallic splitter plate subdivides the contents into half-volumes. One half-volume initially contains fuel vapor diluted with an inert gas, and the other, oxidizer diluted with another inert gas-so that the two domains have equal pressure, density, and temperature. As the separator is removed, by translation in its own plane, through a tightly fitting slit in one side wall, a line ignitor in the opposite side wall initiates a triple-flame propagation across the narrow layer of combustible mixture formed near midheight in the chamber. The planar diffusion flame so emplaced is quickly disrupted in earth gravity. In microgravity, the planar flame persists, and travels ultimately into the half-volume containing the stoichiometrically deficient reactant; the flame eventually becomes extinguished owing to reactant depletion and heat loss to the walls.

SUBJECT TERMS:
Diffusion flame; Microgravity combustion; Stefan problem

NUMBER OF PAGES:
63

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