Slanted axial-flow pump devices are widely applied in urban water supply, irrigation and drainage engineering fields. The second law of thermodynamics is applied to investigate the flow loss characteristics of the 30° slanted axial-flow pump model according to the flow loss analysis method of entropy production theory, so that the hydraulic loss characteristics can be revealed in internal flow process of the slanted axial-flow pump. The three-dimensional numerical simulation of the whole flow conduit in slanted axial-flow pump was conducted and the entropy production increased in the flow process was calculated. The location and distribution characteristics of the flow loss of the pump were qualitatively analysed. The results show that the entropy production in impeller is the highest among the pump components. With the increase of flow rate, the proportion of the entropy production in impeller in total value of the pump device increases continuously. The wall entropy production of impeller, guide vane and outlet conduit are lower than the mainstream entropy production, and the mainstream entropy production occupies the dominant position. As the flow rate grows, the proportion of turbulent dissipation entropy production decreases, and the proportion of wall dissipation entropy production increases. At 0.8 Q _bep , the proportion of turbulent dissipation entropy production is close to 74%, which is about 2.8 times that of wall entropy production. Under 1.2 Q _bep condition, the proportion of turbulent dissipation entropy production is just 5.5% higher than that of wall dissipation entropy production.

Axial-flow pumps may experience significant pressure pulsation and high hydraulic noise when deviating from design conditions, and this article investigates the cross influence of rotational speed and flow rate on inlet pressure pulsation and hydraulic noise of an axial-flow pump based on coherence theory through physical model experiments. The energy amplitude of pressure pulsation is directly proportional to rotational speed and inversely proportional to flow rate, as rotational speed increases, the energy distribution of the blade passage frequency (fBPF) within different frequency bands of pressure pulsation improves. Pressure pulsation and the overall natural frequency of the pump device work together to define the primary and secondary frequencies of the sound pressure level, as rotational speed increases, these frequencies eventually move toward 2fBPF, and the coherence coefficient at frequencies of fBPF and 2fBPF is above 0.9. To reduce hydraulic noise, both pressure pulsation and natural frequency should be given sufficient attention.

To study the significance of internal pressure pulsation characteristics between prototype and model pump devices, monitoring of computational fluid dynamics and dynamic measurement of a model were carried out under different working conditions and measuring points. The results of computational fluid dynamics calculation and model test are as follows. First, the positions of main frequency and subfrequency are almost the same, whereas the amplitude has a slight deviation. Second, the amplitude of inlet impeller is larger, and the main frequency is three times of rotating frequency. Third, the inlet speaker has mainly low pulsation, which is almost distributed in blade frequency and 1/3 times of rotating frequency. Moreover, the pressure pulsation of symmetrical points in each condition has a good symmetry. As the flow rate decreases, both the mixing and blade frequency amplitudes in the inlet speaker and impeller first decrease and then increase. The minimum mixing amplitude appears in the design condition of 253 L/s, whereas the blade frequencies are 203 and 253 L/s. The numerical calculation results are almost the same as those of prototype and model devices. Therefore, numerical calculations and experimental studies on pressure pulsation can guide the design and stable operation of similar pump stations.

To improve the problem of turbulence in the forebay of the lateral inlet pumping station, a typical lateral inlet pumping station project in Xuzhou, Jiangsu Province, China was taken as the research object. The forebay of the pumping station is a building connecting the river channel and the pumping station into the water tank. Based on the Reynolds-averaged Navier-Stokes (RANS) law and the k-ε turbulence model, the computational fluid dynamics method (CFD) technology compares and analyzes the numerical simulation with or without rectification measures for the forebay of the lateral intake pumping station when multiple units are operating. The three-dimensional model was created by SolidWorks modeling software and the numerical simulation simulated by CFX-ANSYS. To alter the flow pattern in the forebay of the pumping station, various rectification measures were chosen. Internal rectification flow patterns in the forebay under multiple plans, uniformity of flow velocity distribution in the measuring section, and vortex area reduction rates are investigated and compared. Based on the analysis and comparison of numerical simulation results, when the parabolic wall and some rectification piers are set significantly it improves the flow pattern of the forebay of the lateral inlet pumping station. It also makes the flow pattern of the inlet pool better and increases the uniformity of the flow velocity distribution by 8%. Further, it reduced the vortex area by 70%, effectively improving the operating efficiency of the pump. The research results of this paper provide a technical reference for the improvement of the flow pattern in the forebay of the lateral inlet pumping station.

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.