Two-phase flow behavior observed in a transparent inverted U-bend pipe

The bubble velocities, bubble trajectories, bubble aspect ratios for two-phase flow in an inverted U-bend channel were measured as function of bubble sizes. In addition, average void fractions were measured at two stations approaching the bend. Large bubbles tend to move straight upward while smaller stay closer to the inner curvature and tend to flow thru flow stream. Bubble aspect ratio varies with bubble size and show several anomalies. The slope C/sub O/ and the drift velocity used in drift-flux model tend to change when flow approach the bend