Gas-liquid flow at microgravity conditions: Flow patterns and their transitions

The prediction of flow patterns during gas-liquid flow in conduits is central to the modern approach for modelling two-phase flow and heat transfer. The mechanisms of transition are reasonably well understood for flow pipes on earth where it has been shown that body forces largely control the behavior observed. This work explores the patterns which exist under conditions of microgravity when these body forces are suppressed. Data are presented which were obtained for air-water flow in tubes during drop tower experiments and Learjet trajectories. Preliminary models to explain the observed flow pattern map are evolved.