The forebay of a pumping station is an important building connecting the diversion channel and the intake pool. Based on the physical model test and research method of computational fluid dynamics (CFD) based on the improved fluid volume model, the flow field in a forebay of a multi-unit pumping station is analyzed in combination with the engineering practice of the Exi River flood discharge station in the Anhui Province, China. Aiming at the technical problems of a large-scale swing water area in the forebay internal flow field of a lateral intake pumping station, the technical problems are discussed. Different rectification measures are selected to adjust the flow pattern in the forebay of a pumping station. The internal rectification flow pattern in the forebay under different plans, the uniformity of flow velocity distribution in the measurement section, and the reduction rate of the vortex area are studied and compared, and the optimal plan is given. The results show that the flow pattern of the 7.5 m and 15 m solutions of the lengthened inflow wall is still poor, and the ability to eliminate vortices is not strong or even counterproductive. The combination plan of a rectifier sill and a rectifier pier has a better effect and can eliminate more than 90% of the vortex, but the uniformity of flow speed has not been significantly improved at the inlet of the pumping station; the combination plan of a rectifier sill and a diversion wall opening has the best effect; the reduction rate of the vortex area is more than 85%, and the velocity uniformity of three measuring sections is better than that of the original plan. The uniformity of flow rate near the pumping station is increased by 4% and that far away from the pumping station is increased by 13%. The combination plan of a rectifier sill and diversion wall with openings is recommended.

Fluid-structure interaction (FSI) was used to determine the structural mechanical characteristics of full tubular and axial-flow pumps. The results showed that as the flow rate increases, the total deformation and equivalent stress are significantly reduced. The max total deformation (MTD) and the max equivalent stress (MES) of the full tubular pump impeller occur on the outer edge of the blade. There are two stress concentrations in the full tubular pump impeller, one of which is located in the outlet area of the rim, and the other is located in the outlet area of the hub. However, the MES of the axial-flow pump appears in the center of the blade hub. The performance difference between the full tubular pump and the axial-flow pump is mainly caused by the clearance backflow. The natural frequency of the full tubular pump is lower than that of the axial-flow pump on the basis of the modal results. The MES of the full tubular pump is mainly concentrated at the junction of the blade and the motor rotor, and the max thickness of the rim is 6mm, which can be more prone to cracks and seriously affect the safety and stability of the pump.

The deflection flow of inlet passage seriously affects the performance of axial flow pump devices, and reduces the operation efficiency and stability of pumping station systems. In this paper, the influence of different deflection angles on the internal flow characteristics and outlet pulsation characteristics of the inlet passage of the vertical axial flow pump are studied. Based on the Reynolds time-averaged N-S equation of the three-dimensional incompressible fluid and the standard k-ε turbulence model, the model axial flow pump device was numerically simulated. Under optimal working conditions (Q_bep = 31.04 L/s), the internal flow field of the axial flow pump was analyzed to study the change law of the axial flow pump performance under different deflection angles. Under the flow conditions of 0.6 Q_bep, 1.0 Q_bep and 1.2 Q_bep, the pulsation characteristics of the outlet of inlet passage in axial flow pump at different deflection angles were analyzed. The result shows that with the increase of the deflection angle, the flow pattern of the inlet passage becomes turbulent, forming vortices of different sizes, the hydraulic loss of the inlet passage increases continuously, and the uniformity of the outlet flow velocity of the inlet passage increases first and then decreases. The time-domain waveform of outlet of the inlet passage at the pressure pulsation monitoring point has obvious periodicity, and the dominant frequency of the monitoring point is four times the rotation frequency, which corresponds to the number of impeller blades. It shows that the numerical calculation is in good agreement with the experimental results, which proves the reliability and validity of the numerical simulation calculation.

This paper presents an investigation of external flow characteristics and pressure fluctuation of a submersible tubular pumping system by using a combination of numerical simulation and experimental methods. The steady numerical simulation is used to predicted the hydraulic performance of the pumping system, and the unsteady calculation is adopted to simulate the pressure fluctuation in different components of a submersible tubular pumping system. A test bench for a model test and pressure pulsation measurement is built to validate the numerical simulation. The results show that the performance curves of the calculation and experiment are in agreement with each other, especially in the high efficiency area, and the deviation is minor under small discharge and large discharge conditions. The pressure pulsation distributions of different flow components, such as the impeller outlet, middle of the guide vane, and guide vane outlet and bulb unit, are basically the same as the measurement data. For the monitoring points on the impeller and the wall of the guide vane especially, the main frequency and its amplitude matching degree are higher, while the pressure pulsation values on the wall of the bulb unit are quite different. The blade passing frequency and its multiples are important parameters for analysis of pressure pulsation; the strongest pressure fluctuation intensity appears in the impeller outlet, which is mainly caused by the rotor–stator interaction. The farther the measuring point from the impeller, the less the pressure pulsation is affected by the blade frequency. The frequency amplitudes decrease from the impeller exit to the bulb unit.

Vortex breakdown in a pump sump is a complex and negative factor for the pump. Different from my previous study that focused mainly on the development process of vortex and its damage to the pump, this paper is from a new perspective that studies the energy dissipation and time–frequency characteristics induced by vortex breakdown. The tested data of pressure and velocity in the process of vortex breakdown were obtained by the model. Considering the gas–liquid two-phase flow of the vortices, a new numerical simulation approach is conducted and verified. The results show that the development rules of vortex breakdown reveal that the breakdown is initiated near the blade. The residual disturbance in the flow field continues to propagate after vortex breakdown, inducing unstable flow inside the runner and causing additional energy dissipation. The time–frequency characteristics induced by vortex breakdown indicated that the runner rotation speed has a significant effect on the vortex breakdown. The frequency of vortex breakdown is relatively small under high-speed rotation. Through discussion, it can be concluded that in order to reduce the harm of vortex breakdown, it can take measures such as controlling the impeller rotation speed, stalling anti-vortex measures, and adjusting operating conditions.

Bidirectional axial extended tubular pumps (BAETPs) are used in low-head pumping stations. This work used both experiments and numerical simulation to investigate the energy dissipation of BAETPs with various blade angles (the blade angle significantly impacts energy loss). Results show that the impeller produces the highest entropy compared with the other pump components. At blade angles of 0°, −2°, and −4°, the unit produces an entropy of 262, 197, and 144 W/K. As the blade angle increases, the ratio of entropy production in the impeller to the total entropy production of the pump steadily rises, the same ratio for the guide vane remains constant at 25%, and the ratio for the S-shaped elbow decreases sharply. Turbulent entropy production rate in the impeller is primarily concentrated in the blade inlet and outlet. Wall entropy production rate in the impeller is focused on the inlet edge of the impeller blade and tip clearance. High entropy production rate (HEPR) occurs at the blade tail due to the rotation of impeller and tip clearance leakage at the area between the impeller and guide vane. Inside the guide vane, the highest entropy production occurs at the guide vane outlet. The HEPR zone on the suction surface of the guide vane is curved and shifts gradually toward the center of the guide vane passage.