In order to explore the cause of the flow pattern problem in the forebay of the pumping station at the diversion operating condition in Taihuzhuangyuan in Changzhou City, and find the corresponding solution, the three-dimensional turbulent numerical simulation method was used to calculate the inlet flow pattern after the prototype of the lock station and the addition of the diversion pier. By analyzing the flow uniformity and weighted average angle of the inlet section in each case, it can be concluded that the flow pattern of the forepbay is mainly caused by the large diffusion angle. The longer a single diversion pier is added to the forebay, the better the rectification effect will be. Compared with the single pier, the combined pier can weaken the recirculation region more and improve the inlet flow pattern. The research results can provide reference for engineering practice.

Aiming at the problem of sluice flow, based on the smooth particle hydrodynamics method (SPH), the boundary treatment method was improved, and the main parameters of repulsion force were re-calibrated, which can avoid non-physical oscillation with n₁=4 and n₂=2. At the same time, the comparison and selection of water replenishment modes were carried out, and it was clear that the bottom hole water replenishment mode with 3 m elevation difference in the optimal water replenishment mode can reduce the net outflow of particles from the upstream water body. On this basis, the numerical model of the flow through the gate impacting the stilling pool downstream was established, and the process of the flow from the sluice to the stilling pool was simulated. The results show that at the initial time, the maximum pressure at the bottom of the upstream water is 127.4 kPa; At the 7th second, the average velocity at the right end of the stilling pool is 7.07 m/s, at the 19th second, the average velocity at the right end of the stilling pool decreases to 1.4 m/s. Thus, the SPH method can accurately simulate the changes of flow velocity, pressure and flow pattern in the discharge process.

The influence of inlet blade setting angle valued in a large range was studied on the performance of residual energy recovery turbine. Firstly, the theoretical predicted model was established between the inlet setting angle and optimal unit speed, and the numerical simulation model was determined based on the characteristics of residual energy recovery turbine. Then, three runners with different inlet setting angle were gave for the residual energy recovery turbine in water distribution networks, and numerical simulations were carried out with the same conditions of flow rate, head and rotate speed. The flow field and performance of the runner were compared. The results show that the optimal unit speed of residual energy recovery turbine was negatively correlated with the inlet setting angle. The range of best numerical predicted efficiency is between 92.72% and 93.60% while the inlet setting angle is between 30° and 70°. The inlet setting angle and optimal efficiency was hardly correlated. However, the range with high efficiency was corresponded to a larger unit speed with the decrease of inlet setting angle. It is feasible for residual energy recovery turbine to increase working range by changing inlet setting angle. The conclusions could provide a reference for the design of residual energy recovery turbine.

The medium and long-term runoff simulation can provide a scientific basis for the rational allocation of water resources, which is of great significance to the high-quality development of the basin. Based on the improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) and singular spectrum analysis (SSA) two-stage decomposition strategy, the monthly runoff simulation model ICEEMDAN-SSA-WOA-LSTM was constructed by using the long short-term memory network model (LSTM) optimized by the whale optimization algorithm (WOA). It was applied to the simulation of monthly runoff in Stone River Reservoir and compared with the single decomposed ICEEMDAN-WOA-LSTM, SSA-WOA-LSTM and the undecomposed WOA-LSTM models. The results show that the ICEEMDAN-SSA-WOA-LSTM model has the best simulation effect, and the three evaluation indexes in the calibration period and validation period are better than other models, with the root mean square error of 1.278 m³/s, the average absolute error of 0.893 m³/s, and the Nash efficiency coefficient of 0.985 in the validation period. The two-stage decomposition strategy model can significantly improve the accuracy of monthly runoff simulation and can be used for year-round incoming runoff simulation.

In order to accurately grasp the actual operation of the governor of hydropower units, this paper proposed a multi-dimensional verification method of the governor operation data of hydropower units based on correlation analysis. The multi-dimensional correlation verification architecture was constructed to process the multi-dimensional operation data of the unit governor. The correlation analysis method was used to calculate the correlation degree between the multi-dimensional operation data change sequences, and the anomaly identification of the multi-dimensional operation data was completed by judging the range of the correlation degree. Based on the characteristics of the identified abnormal data, abnormal data reconstruction was completed from three dimensions of single point, multi-point and continuous abnormal data respectively to achieve multi-dimensional verification of governor operation data of hydropower units. The experiment shows that the method can effectively identify the abnormal data, reconstruct the missing data, reduce the abnormal rate of data through verification, and improve the availability of the governor operation data of hydropower units.

In order to realize the prediction of industrial water consumption and improve the prediction accuracy, a mixed strategy was introduced to optimize the sparrow search algorithm (SSA) for improving the global search ability. The improved sparrow search algorithm (ISSA) was used to optimize the parameters of support vector machine (SVM). A support vector machine model (ISSA-SVM) based on hybrid strategy and ISSA was established, and the prediction of industrial water consumption in Ningxia was taken as an example. The results show that the ISSA-SVM model has the characteristics of fast optimization speed and high precision, and it has good applicability and feasibility in industrial water consumption prediction.

In order to improve the accuracy of runoff prediction, based on the control variable method and the daily runoff data of Lanzhou hydrometric station from August 2001 to December 2019, the models of the LSTM, ARIMA, SVR and XGBoost were used to establish 12 model schemes, including single model, EMD decomposition and reconstruction, EMD decomposition and reconstruction after removing noise components, and evaluation indicators of the 12 schemes were compared. The results show that the EMD sequence decomposition and reconstruction technology and noise component elimination based on Hurst exponent are helpful to improve the prediction accuracy. Compared with the single model, the R_RMSE of the model constructed by the former decreased by 15.16% on average, and that of the latter decreased by 28.49% on average. Among the 12 schemes, EMD-SVR-ARIMA with noise components removed is the best model.

The shear performance of heterogeneous concrete is very important. In this paper, the parallel bonding model of particle discrete element was used to simulate the direct shear test process of concrete to reveal the shear characteristic and failure mechanism of concrete. The impacts of meso parameters, such as contact modulus, contact stiffness ratio, particle friction coefficient, tensile strength, ratio of cohesive strength to tensile strength, and contact friction angle, on the results of concrete direct shear test results were studied by controlling the variable parameters. The shear deformation resistance of specimen has a significant linear relationship with the contact elastic modulus. The contact stiffness ratio has little impact on the shear test results. Particle friction coefficient, contact tensile strength, ratio between cohesion strength and tensile strength, and contact friction angle have a significant effect on the shear strength parameters. Contact tensile strength, ratio between cohesion strength and tensile strength, and contact friction angle could affact the curve form after peak of shear stress vs. horizontal displacement. This paper provided a reference for particle discrete element simulation of direct shear test of concrete specimens.

To decrease the costs associated with wave energy conversion and improve the performance of wave energy converters (WECs), a multi-float WEC that also serves as a breakwater is proposed, and its hydrodynamic performance is explored through physical model tests. The control variable method was used to investigate the free water surface, the dynamic response of the floats, and the energy conversion of the device under different PTO damping loads and wave conditions. These tests allowed for an analysis of the wave energy capture, as well as the device’s ability to prevent and dissipate waves. The test results show that the device functions well as a breakwater, with an average transmittance of 0.48 under typical test conditions, meaning that less than a quarter of the wave energy is transmitted to the rear of the device. Moreover, the device can effectively convert wave energy, with K_e exceeding 20% within the range of 0.64≤kh≤1.39 under suitable PTO loads.

In order to study the impact of the dam break of the Huiling tailings pond in Guangxi on the downstream region, a three-dimensional model of the tailings pond region conforming to the actual terrain was established with the help of GOCAD and Rhino software. In addition, PFC3D discrete element simulation software was used to simulate the state of dam break when the tailings pond runs to the final accumulation elevation +490 m, and the possible submerged range of tailings discharge and the area affected by tailings debris flow were analyzed. The results show that the evolution rate of tailings debris flow increases rapidly to the maximum value in a short time after dam break, and then decreases gradually. The farther away from the dam site, the faster the reduction of tailings debris flow evolution rate is. When the evolution time of dam break is 1 100 s, the furthest evolution distance of tailings is 1 215 m at the foot of tailings dam, the maximum width of the drainage body is 853 m, and the maximum depth is about 30 m. In the process, many sensitive points are submerged. The research provides decision-making information for early warning, personnel evacuation and flood relief of tailings pond accident.