Bubble size and system pressure effects on the phase distribution for two-phase turbulent bubbly flows

The coupled Eulerian-Lagrangian approach was used to study the effects of bubble size and high-pressure transport behaviour on the phase distribution mechanisms in vertically upward air water two-phase bubbly flows. The approach solves the conservation equations of liquid phase in Eulerian space and equations of motion in conjunction with the random walk method for dispersed air bubbles in Lagrangian space. Numerical calculations were performed under conditions of three bubble diameters (2.8, 4.0 and 5.0 mm) and two different pressure levels (0.1 and 7.17 MPa) to explore the flow and void fraction development phenomena. Simulation results indicate the tendency of higher slip ratios and the movement of the void fraction peak towards the flow core for larger gas bubbles. In the pressure range 0.1-7.17 MPa, predictions reveal that the effect of high-pressure transport behaviour on the phase distribution is insignificant.