Effects of buoyancy on steady hydrogen gas-jet diffusion flames

Laminar gas-jet diffusion flames of a nonsooting, fast reacting fuel were investigated at atmospheric pressure in microgravity and at different pressures in normal gravity. These weakly luminous flames were visualized and quantified using the rainbow schlieren deflectometry. The results show that the overall features of the microgravity flame are replicated in normal gravity experiments at sub-atmospheric pressures. The flame width in microgravity correlated with that in normal gravity, when the normalized Froude number at the burner exit was used as a parameter. Normal gravity experiments at low pressures produced nonbuoyant flames that remained parallel to the burner tube regardless of the tube's orientation with respect to the gravitational vector.