Numerical Study on the Effect of Gas Void Fraction on the Performance of Deep-Sea Multiphase Pump

In this paper, the CFD numerical simulation method is used to carry out the numerical simulation of the fire new self-designed deep-sea mixed-flow multiphase pump under the single-phase pure water and air-water two-phase conditions respectively. Under the single phase condition, the pressurization characteristic and hydraulic efficiency of the multiphase pump at three speeds of 3000rpm, 3500rpm and 4000rpm are studied with the change of liquid flow Q_l. Under the two-phase condition, the two-phase pressurization performance of the multiphase pump with constant liquid flowQ_l changing the inlet volume gas void fraction GVF and constant GVF changing Q_l is predicted. The range of GVF is 0∼10%, and the range of Q_l is between 5 m³/h and 90 m³/h. The results show that the mixed-flow multiphase pump has a good pressurization performance and can maintain safe, efficient and stable operation when the GVF is less than 10% in the air-water two-phase conditions. It is found that the gas accumulation near the local area of suction surface of guide vane at the inlet of diffuser is the main reason that the pressurization performance of the mixed-flow multiphase pump decreases slightly with the increase of GVF.