This work seeks to apply the computational fluid dynamics–population balance model (CFD–PBM) to investigate the gas distribution and flow mechanism in the gas–liquid two-phase flow of a centrifugal pump. The findings show that the numerical simulation accurately captures the bubble distribution characteristics in the process of coalescence and breakage evolution. In addition, comparing the CFD–PBM with the Double Euler, the hydraulic head of the pump are similar, but the efficiency using the Double Euler is much higher—even close to single-phase. This is in contrast to previous experimental research. Then, the unsteady flow usually led to the formation of bubbles with larger diameters especially where vortices existed. In addition, the rotor–stator interaction was a main reason for bubble formation. Generally, it was observed that the coalescence rate was greater than the breakage rate; thus, the coalescence rate decreased until it equaled the breakage rate. Thereafter, the average diameter of the bubble in each part tended to be stable during the process of bubble evolution. Finally, the average diameter of bubbles seemed to increase from inlet to outlet. The results of this study may not only enhance the gas–liquid two-phase internal flow theory of centrifugal pumps, but also can serve as a benchmark for optimizations of reliable operation of hydraulic pumps under gas–liquid two-phase flow conditions.
Expected coalescence rate of double neutron stars for ground-based interferometers
