Internal and surface phenomena in heterogeneous metal combustion

Aluminum particles were formed with initial velocities close to zero, ignited and burned in air in normal and in microgravity environments. Combustion times and temperatures were measured to be similar to those in normal gravity conditions. A nonsymmetric flame developed around a nearly motionless aluminum particle burning in air. This is shown to be an intrinsic feature of aluminum burning rather than the result of forced or natural convection flows. Burning particle brightness oscillations were also observed in microgravity experiments, and they may be associated with particle spinning.