In order to solve the blockage effect and energy dissipation phenomenon caused by cavitation in the low-pressure vortex core region, this paper analyzes the spatial evolution of vorticity intensity and turbulent kinetic energy intensity under different cavitation conditions based on the Wray–Agarwal (WA) model. First, the tip leakage flow characteristics are studied, the evolution of vorticity and vorticity intensity is analyzed, then the distribution of turbulent kinetic energy distribution in the blade tip region is studied, and finally, the vorticity transport characteristics of the tip region are analyzed. It is found that the tip leakage rate is less affected by the vortex cavitation of the tip leakage, and there is a strong interaction between the leakage flow at the tip leading edge and the trailing edge, and the separation vortices and low-speed regions formed in the end-wall region cause blockage of the flow passage. Low pressure causes cavitation to cover most regions of the suction surface, inhibiting the formation and development of the tip leakage vortices. The distribution range of high turbulent kinetic energy region is almost the same as that of high-vorticity region, and there is a positive correlation between the two intensities. Severe cavitation causes the high turbulent kinetic energy region at the outlet of the flow passage to develop in the radial and axial directions of the impeller, which increases the turbulent dissipation and energy loss. The change of vorticity transport intensity caused by cavitation is mainly reflected in the expansion contraction term, and the Coriolis force term plays a dominant role in the vorticity transport process. This paper provides a reference for further improving the performance of mixed-flow pumps.

To study the spatiotemporal evolution process of particle wakes behind the impeller in the centrifugal pump, this paper utilized high-speed photography to capture the particle motion characteristics under different solid-phase particle concentrations (1%, 1.5%, and 2%). First, this paper studies the changes in hydraulic performance of the centrifugal pump under solid–liquid two-phase flow conditions. It then introduces the evolution process of the impeller particle wake, comparing the differences in particle wake evolution under varying solid-phase concentrations. Finally, the impact of the solid-phase concentration on the wear of the volute's partitions is investigated. This study found that as the solid-phase particle concentration increases, the hydraulic performance of the pump gradually declines. Under the design conditions, when the solid-phase concentration increases by 0.5%, the efficiency of the centrifugal pump decreases by 0.56% and 0.35%. There is mutual transport of particles between adjacent wakes, and the movement of particle wakes within the volute passage is not equidistant over time. As the solid-phase particle concentration increases, wake cutting occurs at the volute partitions, and there is a significant solid–liquid separation between the particle wakes. The spatial evolution of the particle wakes is significantly influenced by the solid-phase concentration. Wear at the volute partitions intensifies with increasing solid-phase concentration and is also affected by changes in the particle wakes. The research results provide a basis for further exploration of the solid–liquid two-phase flow dynamics within centrifugal pumps.

To accurately investigate the solid–liquid flow mechanisms within the pump, this study employs an improved Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) approach to examine the solid–liquid interactions in a centrifugal pump. First, the improved CFD-DEM is introduced, focusing on turbulence dissipation near the wall and velocity reconstruction. Then, a comparison is made between the CFD-DEM's performance before and after the enhancements. Finally, an analysis is conducted on how the dynamic characteristics of particles within the pump vary under different solid phase concentration conditions. The study revealed that the particle distribution from the corrected CFD-DEM aligns more closely with the experimental results. At a 2% concentration under the design conditions, the head error was reduced by 0.476%, while the efficiency error decreased by 0.076%. Additionally, as the solid phase concentration increased, there was a corresponding rise in the impact power loss of the particles, dissipative power loss, collision frequency, peak values of particle collisions, and the degree of overlap during these collisions. The comparison revealed that the pressure gradient force has the most significant impact on particle motion. As the pressure gradient force increases, the shear power dissipation of the particles also rises. For solid phase concentrations ranging from 1% to 4%, the average shear power variation during the computation period is between 4.28 × 10−6 W and 5.68 × 10−6 W. As the solid phase concentration increases, the volume fraction of the solid phase distribution on the component wall also gradually rises. These findings provide valuable insights for enhancing the accuracy of research on solid–liquid flow in centrifugal pumps.

To accurately study the effect of particle density on the wear characteristics of centrifugal pumps, improvements have been made to the four-way coupling method. This paper first introduces the enhancement strategy for the four-way coupling method, focusing on the turbulence dissipation near the wall and the reconstruction of the velocity field. It then investigates the wear characteristics of the centrifugal pump wall and finally explores the interactions between particles. This study found that as particle density increases, the wear on the centrifugal pump wall also increases accordingly. Wear primarily occurs on the pressure side of the blades, the rear cover plate of the impeller, and the walls of the volute. The collision intensity between particles and the blade wall is significantly affected by particle density with the collision intensity on the pressure side of the blade being higher than on the suction side. As the particle density increases, the sliding distance of particles on the blade wall gradually decreases. The collision intensity on both the rear cover plate of the impeller and the walls of the volute increases with the particle density with the impact on the volute wall being particularly significant. As the particle density rises, the pressure gradient force acting on the particles also increases, and there is a positive correlation between the force on the particles and wall wear. The energy loss resulting from particle collisions increases with particle density, but the rate of increase in energy loss slows down as the density continues to rise. The results provide a reference for further study of solid–liquid flow in the pump.

To investigate the energy dissipation mechanisms within the pump and improve the computational accuracy of the solid–liquid flow numerical simulations, in this study, an improved CFD-DEM (Computational Fluid Dynamics - Discrete Element Method) method has been presented. First, the improved method of CFD-DEM is introduced, which mainly considers the turbulent dissipation of particles in the near-wall region and velocity field reconstruction. Then, the simulation results before and after the method's enhancement are compared. Finally, the analysis of the energy characteristics of the liquid phase flow field in the solid–liquid flow is conducted. Research shows that the modified CFD-DEM method significantly improves the accuracy of the particle distribution predictions, with the numerical results for head and efficiency being much closer to experimental values. In the high-speed regions of the impeller flow field, primarily located behind the pressure side of the blades, the liquid phase flow velocity and pressure fluctuations are less affected by changes in solid phase concentration. In the fluid region of the centrifugal pump, the energy loss caused by entropy production is significantly concentrated in the volute and impeller regions. Specifically, the entropy production dissipation in the volute region accounts for the substantial portion of the total entropy production, approximately 67%–68%, while the entropy production dissipation in the impeller region accounts for about 19.7%–20.4%. As the solid phase concentration increases, the energy dissipation within the pump gradually rises, and the total vorticity at the impeller inlet also increases correspondingly, with the vorticity distribution being related to the number of blades. The findings provide a reference for further exploring solid–liquid flow within centrifugal pumps.

This study presents a comprehensive investigation of the internal noise characteristics of a mixed-flow pump by combining computational fluid dynamics (CFD) and computational acoustics. The turbulent flow field of the pump is simulated using the unsteady SST k-ω turbulence model in CFD. The contributions of the volute, guide vanes, and impeller to the internal noise are analyzed and compared using the Lighthill theory, FW-H formula, and LMS Virtual Lab software for acoustic simulation. The research findings indicate that the energy of pressure fluctuations in the mixed-flow pump is predominantly concentrated at the blade passing frequency and its low-frequency harmonics. This suggests that the internal noise is mainly in the low-frequency range, with higher energy at the blade passing frequency and its harmonics. Under the 0.6Q_des flow condition, the flow inside the pump becomes more complex, resulting in higher sound pressure levels and sound power levels compared to higher flow conditions. However, for flow conditions ranging from 0.8Q_des to 1.2Q_des, the sound pressure levels gradually increase with increasing flow rate, with the sound pressure level at 1.0Q_des being nearly identical to that at 1.2Q_des. The analysis of sound power level spectra at different flow rates reveals that the distribution characteristics of internal vortex structures directly impact the hydrodynamic noise inside the mixed-flow pump. These research findings provide a significant theoretical basis for noise control in mixed-flow pumps.