Pump station engineering is extensively utilized in water supply and drainage, as well as agricultural irrigation. Due to its geographical advantages and significant comprehensive benefits, the construction of pumping stations in coastal areas has gained substantial attention in recent years. Adverse flow conditions caused by various factors negatively affect the inlet flow regime of pumps, becoming a key factor that restricts the operating life and further development of pump station systems. Optimizing the flow regime in the forebay is crucial for enhancing overall engineering quality, minimizing pump performance degradation, and reducing the risks of cavitation and vibration. This study investigates the flow characteristics of the forebay by combining the Navier–Stokes equations and the $k-\epsilon$ RNG turbulence model. The analysis focuses on the internal flow field, transverse flow before the inlet channel, and the uniformity of flow velocity distribution after the inlet channel. Numerical simulations are validated through physical model tests. We examine the flow characteristics in the forebay, analyze the causes of internal flow disorder, and propose a reasonable and practical rectification scheme for the forebay. Additionally, we elucidate the mechanism of flow state optimization through partition walls. The findings indicate that with the optimal partition wall length, the average elimination rate of transverse flow velocity before the pump station inlet channel reached 48.3%, and the uniformity of flow velocity distribution after the inlet increased by 3.24%. These research findings contribute to mitigating cavitation and vibration in water pump units, providing theoretical support for the safe operation of coastal pumping stations.

A slanted axial-flow pump is extensively applied in coastal pumping stations; however, severe bias flow within the outlet passage will result in unstable operation and low efficiency of the slanted axial flow pump system. In order to mitigate bias flow in a slanted axial-flow pump outlet passage, seven exit setting angle schemes of the guide vanes were designed. The influence mechanisms of the guide vane exit setting angle on internal flow characteristics, hydraulic loss, flow deviation coefficient, vortex evolution patterns, and pump system efficiency were systematically investigated. The results demonstrate that under design flow conditions, as the exit setting angle of the guide vane ranges from 90° to 105°, the flow field in the first half of the guide vane remains essentially the same. The low-velocity region at the guide vane outlet demonstrates initial contraction followed by gradual expansion with increasing stagger angles. Looking downstream within the flow passage from the left to the right, the hydraulic loss in the outlet passage goes up after an initial descending trend as the exit setting angle increases. When the exit setting angle is 97.5°, the bias coefficient of the outlet passage is 1.031. At this point, the vortex core distribution intensity within the outlet passage reaches a minimum, corresponding to the lowest recorded hydraulic loss of 0.230 m. Compared with the original guide vane scheme, the scheme with an angle set at 97.5° can improve the pump system efficiency of the slanted axial flow pump system, whether the flow is set at a design point or at a large point, and the pump system efficiency is increased by 2.3% under design flow conditions.

To improve shutdown safety for agricultural irrigation pumping stations, this study investigates the synchronous and asynchronous shutdown processes of a pump device using numerical simulations validated by model tests. The results show that during the synchronous shutdown process, vortices appear on the inside of gate as its opening decreases, and their ranges expand accordingly. When the gate is 90% closed, negative pressure zones emerge in the outlet passage. As the gate continues to close, the strength and range of negative pressure zones keep expanding, and air is drawn into the outlet passage. After the gate is fully closed, the water flow starts reciprocating motion with strength attenuation due to inertia and water pressure. Compared with the synchronous shutdown method, the asynchronous shutdown-F1 to F4 achieved significant reductions results: the maximum reverse rotation rate decreased by 17.74%, 39.59%, 59.18%, and 83.35%, respectively, while the maximum reverse volumetric flow rate decreased by 17.32%, 38.45%, 59.20%, and 79.19%, respectively. Furthermore, in asynchronous shutdown-F4, no negative pressure occurs in the outlet passage, even if the gate closes suddenly. Therefore, the asynchronous shutdown method is a safer alternative for irrigation pumping stations. This study proposes more appropriate shutdown methods for pumping stations, which has significant practical value.