This paper focuses on the renovation project of Jianzhong Pumping Station in Hebei Province. The computational fluid dynamics (CFD) technology was used to optimize the rectification measures of the forebay of the side-inlet axial flow pump, as well as the inlet and outlet flow passages, and simultaneously predict the energy performance of the pump unit. Based on the CFD optimization of the inlet and outlet flow passages of the pump unit, a model test study of optimization scheme for pump unit was carried out. The test results show that the efficiency of the pump unit reaches 73.8% under the design lift, which is basically consistent with the prediction conclusion of the CFD method. This study indicates that when optimizing the flow passage design of the axial flow pump unit, giving priority to using the CFD technology to select the optimal schemes for the inlet and outlet flow passages of the pump unit and then verifying through the model test of the pump unit can greatly save the investment cost and accelerate the project progress, providing a reference for similar projects.

In the operation of hydroelectric generating unit, thrust bearings generate a considerable amount of residual heat due to load-bearing, friction, and other factors. Poor heat dissipation performance of lubricating oil can give rise to the tile burning phenomenon, thus causing massive economic losses. Nanoparticles can not only improve the lubrication characteristics of lubricating oil but also enhance the heat transfer process of lubricating oil. Accordingly, through numerical simulation, this study examined the heat dissipation enhancement effect of lubricating oil in thrust bearings when reinforced by nano-copper oxide particles with different concentrations (0.1wt%, 0.3wt%, 0.5wt%). The results demonstrate that the addition of nano-copper oxide can enhance the heat dissipation efficiency of lubricating oil, and the most favorable heat dissipation effect is achieved when the concentration of nano-copper oxide is 0.5wt%.

Under single-nozzle operating conditions, the radial force of the runner for large-scale impulse turbine abnormally increases, severely affecting shafting stability. This study establishes a dynamics model of the bearing-rotor system incorporating the runner, main shaft, and bearing supports. The critical speed and vibration mode characteristics of the shafting system were calculated by using COMSOL Multiphysics software. And then the transient response characteristics under different radial hydraulic thrust forces were analyzed. The results indicate that the first-order critical speed of the unit shafting is 534.49 r/min, meeting the design specification requirements. The radial hydraulic thrust under single-nozzle operation can be considered as a constant radial force. The centroids of shaft orbits in all guide bearings exhibit displacement under radial hydraulic thrust, with the maximum offset observed in the turbine guide bearing. Analysis reveals that during single-nozzle operation, the resultant radial force on the water guide bearing concentrates on the one side, fluctuating within approximately ±1.5° relative to the jet direction. This research can provide reference for structural optimization and operational control of impulse turbine units under special operating conditions.

The joint optimal operation of multi-source gate-dam groups is the key to balance multiple objectives like water level, water quality, water efficiency, and costs in water network scheduling. This study focuses on the cascade scheduling system of the Suqian Yellow River Old Course. Considering water level control, water quality compliance, cost reduction, and efficiency improvement, a multi-source gate-dam joint scheduling optimization model was established by coupling a hydrodynamic-water quality model with the NSGA-Ⅱ algorithm. Using the mechanism of "scheme generation-process simulation-effect evaluation-feedback optimization", the Pareto optimal solution set was iteratively solved. The comprehensive optimal scheduling solution was determined by the entropy weight method. The results show that the significant multi-objective conflicts among water level, water quality, efficiency, and cost in the study area; The cost and efficiency are inversely constrained; The relationship between water quality and water level is non-monotonic; There is a positive synergy interval between efficiency and water level; The cost and water quality mutually restrict each other; The proposed model can effectively balance these four objectives, with the comprehensive optimal solution yielding values of 0, 0.09, 0.24, and 0.12, respectively, achieving integrated optimization compared to single-objective solutions. The proposed method can provide crucial support for solving optimal scheduling problems involving multiple water sources, projects, and objectives.

Small hydropower has the characteristics of small capacity, multi-point distribution and strong basin correlation. The traditional follow-up power generation mode is disorderly, and the flexible and adjustable value of small hydropower groups has not been fully utilized. The evaluation and optimization of adjustable capacity is the key to support the peak regulation of power grid and the accommodation of wind, solar and electricity. Based on the runoff prediction of small hydropower groups in the basin, it is proposed that the output corresponding to the maximum power generation flow of the current water level of small hydropower is the upper limit of adjustable output, and the output corresponding to the ecological installed capacity is the lower limit. The adjustable capacity interval of small hydropower is determined, and then the adjustable capacity optimization model of small hydropower groups in the basin is constructed and an improved particle swarm optimization algorithm is proposed. Taking the five series runoff power stations of Liangqian, Dayan, Kongtou, Fancuo and Gaotang in Jinxi River Basin as an example, the rainfall-runoff process simulation is carried out to analyze the coupling relationship between the storage capacity of small hydropower group and its power generation and inflow flow, and the optimal output and adjustable output interval of small hydropower group in the basin are optimized. The results show that after optimization, the adjustable capacity interval is increased, the upper limit of the adjustment capacity is increased by 12.1 %, and the actual output is increased by 14.6 % compared with that before optimization. The optimized output mode can support the power grid to adjust the output of small hydropower in a larger interval, which can provide decision support for the power grid dispatching department to tap the flexibility value of small hydropower resources and give full play to its peak regulation and consumption capacity.

To systematically investigate the impacts of wind and solar power integration on medium-to-long-term optimal scheduling of the Qingjiang cascade hydropower stations, a multi-objective optimization model for coordinated hydro-wind-solar operation was established. The objective function was reconstructed through objective transformation integrated with penalty mechanisms and solved using the progressive optimization algorithm (POA). Case studies demonstrate that the model simultaneously ensures system power generation while achieving complementary coordination between cascade station operations and renewable power output. Through analysis of complementary coordination effects and reservoir level variations, operational pattern modifications for the Qingjiang cascade reservoirs were extracted: following renewable integration, storage/discharge strategies should be prioritized for adjustment during wet/normal years based on inflow characteristics. This adaptation reserves additional storage capacity to flexibly accommodate complementary coordination requirements with renewables while fulfilling power generation demands.

After the operation of Wudongde, Baihetan, Xiluodu and Xiangjiaba hydropower stations (XJB), the channel conditions in the lower reaches of the Jinshajiang River have been greatly improved, which prompts the ships in this section of the river to increasingly develop towards larger sizes. When encountering the dry inflow from the Jinshajiang River, the water depth of the channel from Xiangjiaba to Yibin River is shallow, and the passage of large cargo ships is difficult, which affects the shipping efficiency of the river section. By analyzing the relationship between the loading capacity of the main ship types and the discharge from XJB, the optimal seaworthy discharge of the river section is obtained. Combined with the actual operation of the ships at the wharf, a tidal shipping scheduling model was established by intermittently releasing the seaworthy flow of XJB, and a variety of schemes were proposed to simulate the calculation. The results show that the XJB can increase the navigation time of large ships, increase the average cargo volume of a single ship by 16%, and increase the power generation head by 0.31 m, and has a positive impact on promoting the exchange of water bodies in the reservoir area. The research results can provide references for regional shipping scheduling management.

The spur dikes are widely applied in marine and estuarine engineering projects, and its surrounding local sediment scouring and silting characteristics directly affects the safety and stability of the project. Existing studies primarily rely on physical experiments or empirical prediction formulas, lacking a deep understanding of the flow structure and sediment transport patterns. Based on the software Delft3D, this paper presents a numerical simulation of the local sediment scouring and silting characteristics of spur dikes under clear water conditions and performs reliability verification. The sediment scouring and siltation characteristics of single dam and spur dike are compared. The diversion characteristics, local bed shear stress and local sediment scouring and siltation patterns of the spur dikes are analyzed, and the impact of dam length and flow velocity is discussed. The results show that the when the spur dike spacing decreases by 40 m, the maximum dimensionless shear stress increases from 2.56 to 7.48. An increase of flow velocity further expands the flow diversion range and the density of streamlines, with the maximum dimensionless shear stress rising from 3.17 to 5.60; The increase is approximately 76.7%, and the area percentage of high shear stress zones increases from 20.27% to 34.44%. Additionally, when the spur dike spacing is reduced by 20 m, the maximum scour value at the dam head increases by approximately 45.89% to 59.92%; When the flow velocity increases, the maximum scour value increases by about 13.41%, while the scour pit area expands and the sediment deposition area spreads. This study can provide theoretical support for optimizzation design of spur dikes.

As a "last resort" for flood control, the effectiveness of flood control projects in flood detention area is crucial for accurately assessing the overall flood control capacity of the area. Based on a one- and two-dimensional coupled hydrodynamic model and scenario analysis method, the effectiveness of flood control projects was evaluated by simulating the flood evolution process in the Xiaoqing River flood-diversion area. The results show that by simulating floods for different recurrence periods before and after the construction of flood control projects and comparing the different evolution results of floods in watercourse and on the surface, the effectiveness of flood control projects can be analyzed in detail, and the overall flood control capacity of the flood diversion area can be effectively evaluated; Three of the flood control projects currently being implemented in the Xiaoqing River flood diversion area in Beijing can achieve the expected flood control effects. Specifically, Project A can effectively protect the flood control safety of the left bank of the Dashijiang River; Project B can facilitate the rapid passage of released flood from the Danning Reservoir through the railway culvert in the flood diversion area; Project C ensures that the discharge of the Xiaoqing River during flood diversion does not exceed 500 m³/s, meeting the requirements of flood control. The proposed method can quantitatively analyze the effect of flood control projects and is of great significance for guiding the planning and construction of flood control projects in flood detention areas and the safety assessment of these areas.

The environmental characteristics of ultra-high altitude areas will affect the air flow and heat exchange process of the ventilation and cooling system of the generator motor, which will lead to the reduction of the cooling effect of the generator motor. In this paper, the key influencing factors of ventilation and cooling system of generator motor in ultra-high altitude environment are analyzed by mathematical model. Based on the finite element simulation, the ventilation and cooling system model of the generator motor is established and quantitatively designed considering the flow field, temperature field and conjugate heat transfer conditions. Finally, the optimal design measures of the ventilation and cooling system of the generator motor under the condition of ultra-high altitude are put forward. The research results provide a theoretical basis for the efficient and stable operation of generator motor in ultra-high altitude environment, which can effectively promotes the technological progress and development of the related industries.