Abstract

For the first time, a comprehensive study of the gravitational effects on laminar premixed gas combustion has been undertaken. Flammability limits, burning velocities, and minimum ignition energies for stoichiometric and lean methane-air mixtures at pressures of 50 to 1500 Torr were measured in normal earth gravity (one-g) and zero-gravity (zero-g). This information is of value for the assessment of flammability hazards of materials used in spacecraft construction, evaluating the effectiveness of spacecraft fire suppression systems, and improving our knowledge of some inadequately understood combustion phenomena. The zero-g flammability limit was always between the one-g upward and downward limits at the same pressure. Burning velocities were identical in one-g and zero-g for fast-burning mixtures. For slow-burning mixtures only the zero-g observations could be interpreted to obtain burning velocity information because of the severe flame front distortion in one-g caused by natural