Characteristics of bubbly flows in a rotating radial duct

This paper concerns experimental investigations on the behavior of air-water two-phase mixtures in a rotating duct with a square section. Hydraulic loss, as well as distributions of pressure and void fraction, were measured for a bubbly flow regime and the loss was discussed in relation to the change in flow patterns and Rossby number. As the rotating speed is increased or the flow rate of water is decreased, i.e., the Rossby number is decreased, a high-void fraction region appears on the downward negative side and tends to expand toward the upstream. Pressure rise in a radial direction is hardly gained in this high-void fraction region, causing substantial increase in the hydraulic loss.