- Author
- Illinois Univ., Department of Aeronautical and Astronautical Engineering
- Title
- Behavior of Lean Methane-Air Flames at Zero-Gravity. Final Report. November 1983-December 1984.
- Coporate
- Illinois Univ., Urbana
- Sponsor
- National Aeronautics and Space Administration, Lewis Research Center, Cleveland, OH
- Report
- Final Report, February 1985, 42 p.
- Contract
- NASA-NCC3-35 AAE-85-2
- Keywords
- combustion | flammability limits | methane | weightlessness
- Identifiers
- zero gravity
- Abstract
- A special rig has been designed and constructed to be used with the NASA Lewis Research Center Airborne Research Laboratory to study the effect of gravity on the behavior of lean fuel-air flames in a standard (one end closed) 50.4 mm. (2") internal diameter tube when the mixtures are ignited at the open end. Design constraints are discussed and the procedure for using the rig is described. The propagation of lean methane-air flames over the range of 5.05 to 6.1 volume percent methane was studied. The lean limit at zero gravity was gound to be 5.10% methane and the flame was found to extinguish as previously observed for downward propagating flames at one g. It was observed that g-jitter could be maintained at less than ± 0.04 g for most zero g trajectories. The flames were found to be sporadically cellularly unstable at zero g. The effects of g-jitter were studied. Upward propagation at two g yielded the expected stable flame cap propagation. When the g level was increased from zero g at ignition to one g downward during propagation of the flame, the flame extinguished at rather low g levels when the methane concentration was less than 5.86% CH4 (the downward lean limit at one g) and did not extinguish at higher methane concentrations.