Effect of gravity on laminar premixed gas combustion. II. Ignition and extinction phenomena
At the initial pressure of 50-1500 torr, the minimum ignition energies and flame radii for near-limit, limit, and sublimit fuel-lean methane-air mixtures burning at one-g and zero-g measured as a function of time, are examined. The same minimum ignition energy values are obtained at one-g and zero-g except for mixtures near zero-g flammability limit and leaner, where the zero-g values are much higher than the one-g values. The unstable flame propagation of sublimit mixtures at zero-g is observed to have a flame radius increasing in proportion to the square root of the time lapse from ignition and sudden extinction. This type of behavior is more pronounced at higher pressures. It is found that a flame-front instability is responsible for the flame extinguishment at zero-g. It is also found that gravitational forces stabilize upward flame propagation. 19 references.
- Research Organization:
- NASA, Lewis Research Center, Cleveland, OH; MIT, Cambridge, MA
- OSTI ID:
- 5538539
- Journal Information:
- Combust. Flame; (United States), Journal Name: Combust. Flame; (United States) Vol. 62; ISSN CBFMA
- Country of Publication:
- United States
- Language:
- English
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