The turbulence dissipation will cause the increment of energy loss in the multiphase pump and deteriorate the pump performance. In order to research the turbulence dissipation rate distribution characteristics in the pressurized unit of the multiphase pump, the spiral axial flow type multiphase pump is researched numerically in the present study. This research is focused on the turbulence dissipation rate distribution characteristics in the directions of inlet to outlet, hub to rim, and in the circumferential direction of the rotating impeller blades. Numerical simulation based on the RANS (Reynolds averaged Navier–Stokes equations) and the k-ω SST (Shear Stress Transport) turbulence model has been carried out. The numerical method is verified by comparing the numerical results with the experimental data. Results show that the regions of the large turbulence dissipation rate are mainly at the inlet and outlet of the rotating impeller and static impeller, while it is almost zero from the inlet to the middle of outlet in the suction surface and pressure surface of the first-stage rotating impeller blades. The turbulence dissipation rate is increased gradually from the hub to the rim of the inlet section of the first-stage rotating impeller, while it is decreased firstly and then increased on the middle and outlet sections. The turbulence dissipation rate distributes unevenly in the circumferential direction on the outlet section. The maximum value of the turbulence dissipation rate occurs at 0.9 times of the rated flow rate, while the minimum value at 1.5 times of the rated flow rate. Four turning points in the turbulence dissipation rate distribution that are the same as the number of impeller blades occur at 0.5 times the blade height at 0.9 times the rated flow rate condition. The turbulence dissipation rate distribution characteristics in the pressurized unit of the multiphase pump have been studied carefully in this paper, and the research results have an important significance for improving the performance of the multiphase pump theoretically.

The pressure pulsation characteristics of the blade’s surface have an impact on the lifespan of the multiphase pump impeller. To explore the influence of the gap matching relation on the pressure pulsation characteristics at blade’s surface of the pump, the axial clearance coefficient (ACC) between the impeller and diffuser and the relative tip clearance of the impeller were defined. By combining of numerical simulation and experiment, the pressure pulsation characteristics at blade’s surface of the single pressurization unit of the pump were studied under different gap matching relations. The results show that the size of tip leakage flow and the strength of rotor-stator interaction caused by different relative tip clearances have a decisive influence on the pressure pulsation characteristics in the impeller. With the increase of tip clearance, the internal flow field distribution law was greatly changed, which had a great impact on the pressure pulsation peak-to-peak value and dominant frequency amplitude of the suction surface. In addition, the pressure pulsation characteristics of the diffuser were mainly affected by the strength of rotor-stator interaction. When the strength of rotor-stator interaction weakened, the amplitude of the dominant frequency pulsation was decreased by degrees. As the ACC increased, the variation of the pressure pulsation peak-to-peak value and the dominant frequency amplitude coefficient were gradually slowed down in the diffuser, and the dominant frequency amplitude of the monitoring points were most sensitive to change in the ACC. The research results can provide a theoretical reference for the optimal design of the multiphase pump blades.

The axial flow screw-type oil-gas multiphase pump is mainly applied to oil and gas transport in the deep sea. In the process of transporting the multiphase medium, the gas volume fraction (GVF) on the gas phase changes from time-to-time, resulting in the performance of the oil-gas multiphase pump being greatly influenced by the gas phase. This paper presents a detailed analysis of the gas-phase distribution law and the vortex distribution in the flow passages within the oil-gas multiphase pump by means of numerical calculations, supplemented by experimental verification. The results show that the gas phase is mainly concentrated in the diffuser at different GVFs, and the gas phase gathering in the diffuser becomes more significant with the increase in the GVF. The gas-phase volume fraction increases gradually from rim to hub, that is, the gas-phase gathering degree increases. The maximum gas-phase volume distribution area is mainly concentrated in the area near the hub of the diffuser inlet and the middle blade height area at the outlet of the diffuser. The flow in the impeller is relatively stable under the different GVFs, while there is a large vortex near the inlet of the diffuser near the hub, and there is a backflow phenomenon between the outlet of the diffuser and the tip clearance of the impeller. The volume fraction of the gas phase near the rim fluctuates more than that near the hub because the gas phase is squeezed by the liquid phase more violently. The research results can provide theoretical guidance for the optimal design of oil-gas multiphase pump blades.

In this paper, the k-ω SST (Shear Stress Transport) turbulence model is employed to study the effect of flow rate on regular patterns of pressure load distribution characteristics on the helico-axial pump impeller blade surface. The results show that all the curves of pressure load distribution of helico-axial pump impeller blade surface at different blade heights under different flow rates show a similar trend of increasing first and decreasing then. At the impeller blade inlet area, with the increase of flow rate, the range of negative blade pressure load in this area gradually increases. When the pump runs under small flow rate conditions, within the range of relative position from 0 to 0.2 of the hub, the work capacity of the hub is obviously stronger than that of other areas of the impeller, while within the range of relative position from 0.2 to 1, the work capacity from hub to rim gradually enhances. With the increase in flow rate, the area with a strong work capacity of the hub gradually expands while the area with a strong work capacity of the rim gradually narrows. The research results can provide a theoretical reference for the optimization design of pump supercharging performance.