Metals combustion at high oxygen pressure in normal gravity and reduced gravity: Model and experiment

The combustion of metals under normal gravity and microgravity conditions was investigated. A model is presented that uses mass and enthalpy balances to describe the combustion occurring in the molten ball that forms during the combustion of iron rods. The effect of gravity in the postulated model was manifested in the time constant ;For the normal gravity combustion of iron rods, it was concluded that (1) there was a large excess of oxygen contained in the molten balls, (2) combustion should occur upon entry of the liquid iron into the molten mass, and (3) oxygen intake into the molten ball was not limiting the combustion or regression rate of the melting surface.;The metals tested in a cylindrical rod configuration in microgravity were flammable under similar conditions that support combustion in normal gravity, but the combustion physics were different. A similar relationship, in normal gravity and microgravity, exists between the ability of cylindrical iron rods to support combustion, and the oxygen pressure and rod diameter. Configurations other than the cylindrical rod can exhibit a change in flammability when the combustion is moved from normal gravity to microgravity. This means some flammability data obtained in normal gravity is valid for microgravity applications and some are not.;Other results from this study include (1) gravity affects the combustion of alloys or the off-gassing that occurs upon cooling of the product oxides, (2) the aluminum combustion zone is different from the combustion zone for iron, (3) the density of the molten ball at detachment, in normal gravity, is approximately 4.61 gm/cm...