Hydrogen diffusion flames under microgravity

Hydrogen diffusion flames with different flow rates have been investigated under gravity and microgravity. The aim of this work is to clear up the separated influences of diffusion and buoyancy on combustion processes. The first results of drop tower investigations are described and compared to ground level data. It will be shown that the well known flame flickering is caused by buoyancy forces. Furthermore, the growth of flame shape under microgravity is analyzed and the disagreement between theory and experimental data for hydrogen flames is explained. The oxygen concentration profile for an earth-bound flame and the corresponding minimum and maximum contours are presented.