In order to improve the hydraulic performance of the hot water circulation pump, the hydraulic efficiency and head of the YGB type hot water circulation pump were taken as the optimization objectives. The Plackett-Burman experimental design method was used to screen the variables that significantly affect the optimization objectives, namely the impeller outlet width, blade wrap angle, and blade outlet setting angle. The accuracy of three machine learning prediction models was compared and an approximate model for impeller structural parameters and hydraulic performance indicators were established based on the XGBoost algorithm. Based on this approximate model, second-generation and third-generation genetic algorithms were used for optimization, and a mapping method was used to select a compromise solution as the optimization model. After optimization, the hydraulic efficiency of the model pump is increased by 3.20 percentage points. By comparing the numerical calculation results of the internal flow field of the hot water circulation pump before and after optimization, it is found that the optimized impeller channel becomes longer and the diffusion degree decreases. The high dissipation area of turbulent kinetic energy at the impeller tail and working face is controlled, and the flow loss is reduced. Based on the theory of entropy production, the local entropy production distribution in the spanwise direction of the impeller is explored. After optimization, the high entropy production areas near the blade tail and midspan are significantly reduced. Under design conditions, the entropy production in the impeller and volute is reduced by 7.84% and 5.58%, respectively, compared with the original model.

To ensure the safe operation of vertical mixed-flow pumps in low-head pumping stations, it is necessary to accurately identify the pressure pulsations in the vaneless space. Based on numerical simulation results, time-series data was constructed and a dynamic mode decomposition approach enhanced by the delayed-embedding property of the Hankel matrix was employed to enable the extraction of dominant dynamic features from one-dimensional signals. The frequency components obtained from this method were compared with those derived from Fourier transform analysis to verify identification accuracy. Three typical flow conditions were examined to analyze the dominant frequencies, energy distribution, and modal characteristics of pressure pulsations in the vaneless region. Signal reconstruction using a limited number of low-order modes was conducted to evaluate error levels and the stability of the method. The results show that the proposed approach effectively identifies the primary frequencies induced by rotor-stator interaction and outperforms the Fourier transform in extracting low-energy components. The low-order reconstruction maintains a high degree of consistency with the original signal, demonstrating good error control. The study concludes that this method can accurately characterize pressure pulsation characteristics of the vaneless region of vertical mixed-flow pumps, and provides valuable technical support for analyzing complex time-series data and assessing the operational safety of pumping stations.

To accurately describe the fiber orientation characteristics in centrifugal pumps under the drag reduction effect and thereby improve the pump efficiency, the existence of the drag reduction effect was verified through hydraulic characteristic experiments. Subsequently, a high-speed camera was employed to capture images of fibers in the fluid, and fiber-related data were collected within the monitoring area to analyze the overall and local fiber orientation. Meanwhile, ANSYS and EDEM software were used to simulate the liquid phase and solid phase, respectively, and the coupling solution of the solid-liquid two-phase flow was conducted to calculate the pressure field, velocity field, and turbulent kinetic energy in the flow field. Thereafter, the fiber orientation characteristics obtained from experiments were cross-validated with the flow field states derived from simulations. The research results show that near the base circle, fibers tend to align with the tangent direction of the base circle. There are differences in fiber orientation tendencies at different positions, with a higher proportion of fibers oriented at small angles on the left and right sides compared to the upper and lower positions. The fiber orientation distribution tends to be discrete under the influence of structures such as impellers or volute tongues. Fibers exhibit obvious orientation tendencies under the drag reduction effect, and the prefe-rential orientation of fibers drives the occurrence of the drag reduction effect. Furthermore, the alignment order of fiber orientation is positively correlated with the stability of the flow field.

To enhance the hydraulic performance of the turbine, an optimization method for turbine splitter blades was established based on the response surface methodology. The value ranges of five parameters including circumferential position, outlet deflection angle, outlet diameter, inlet flow angle, and outlet flow angle of the splitter blade were selected through single-factor tests using numerical si-mulation. Significance analysis of each parameter was conducted using the Plackett-Burman test, and three parameters with significant effects on turbine efficiency were identified: outlet deflection angle, outlet diameter, and outlet flow angle. A regression equation between the structural parameters of the splitter blade and both efficiency and output power was established based on the response surface methodology, and the optimal combination of structural parameters for the splitter blade was obtained. The results indicate that the outlet deflection angle, outlet flow angle, and outlet diameter of the splitter blade have significant effects on turbine performance. When the outlet deflection angle is 4.8°, the outlet flow angle is 23.1°, and the outlet diameter is 80.2 mm, the comprehensive performance of the turbine is optimal. Compared with the original model under design conditions, the optimized turbine shows a 2.9% increase in efficiency and a 5.6% increase in output power. The study demonstrates that the response surface optimization method is beneficial for improving the hydraulic performance of hydraulic turbines with splitter blades.

To improve the hydraulic performance of an axial flow pump station, optimization was carried out on an axial flow pump model with a design specific speed of 900 based on a three-dimensional inverse(3D)design method. The impeller outlet circulation distribution was first divided into three forms: constant, linear, and nonlinear. Through orthogonal experimental design, 32 sets of design schemes were determined respectively within the sample space. Computational fluid dynamics(CFD)technology was employed to perform numerical simulations on the original scheme and three circulation distribution schemes. By controlling eight impeller outlet circulation distribution parameters, parametric design of the impeller was achieved under constant, linear, and nonlinear circulation distribution conditions, and the pump section performance before and after optimization was compared and analyzed. The results show that the variation trend of the impeller outlet circulation under different distribution forms remains basically consistent. Among them, the constant circulation distribution demonstrates the most significant optimization effect, with more stable internal flow and more uniform velocity distribution. Under the design operating conditions(flow rate: 360 L/s, head: 5.4 m), the efficiency reaches 79.24%, indicating a notable improvement through optimization.

To address the issue of low wind energy utilization in small wind turbines, a negative pressure wind turbine model was designed based on the principles of energy concentration and negative pressure power enhancement. Wind tunnel experiments were conducted to investigate the aerodynamic characteristics and power output properties of the negative pressure wind turbine. The experimental results show that the power output growth rate of the negative pressure wind turbine is 133.51% at a wind speed of 7.5 m/s, and decreases to 20.39% at a wind speed of 12.5 m/s, demonstrating an overall trend of decreasing growth rate with increasing wind speed. At a constant wind speed, the closer the negative pressure hole is to the wall surface, the lower the power output. The average output power of the closed upper part of the negative pressure holes is 92.67% of that of the closed lower part. Moreover, the larger the area of the negative pressure holes, the greater the power output of the wind turbine. The average power output when the negative pressure hole opening is 1/3 of the full opening is 30.27% of the full-open condition, and the average output power when the negative pressure hole opening is 1/2 of the full opening is 57.09% of the full-open condition. These conclusions can provide a valuable reference for research on improving wind turbine performance using the principle of negative pressure power enhancement.

To address the problem associated with diagnosing pipe bursts in a long-distance parallel water delivery system, 1 815 pipe burst scenarios were designed, and the pressure variation data at the system pressure gauge installation points were obtained using the characteristic line method. A normal distribution was introduced to generalize the typical pipe burst data into 18 150 sets of pipe burst data with similar characteristics. These were then combined with 370 sets of steady-state data to form a typical state sample set comprising five categories and 19 dimensions. Subsequently, the principal component analysis(PCA)method was employed to conduct pressure feature analysis and dimensionality reduction analysis. Based on the inclusion of pressure drop analysis, two types of sample sets were formed as follows: one with 9-dimensional inputs and another with 18-dimensional inputs. By using methods such as the PSO-optimized BP neural network, three diagnostic models were trained: a 9-input BPNN model, a 9-input PSO-BPNN model, and an 18-input PSO-BPNN model. Finally, the diagnostic accuracy of the model was evaluated. The results from the study demonstrate that the diagnostic accuracy of the PSO-optimized BPNN model is 36.27% higher than that of the conventional BPNN model. The 18-input PSO-BPNN diagnostic model, which considers pressure drop, achieves higher accuracy than the other two models and exhibits excellent stability, with a diagnostic error of only 1.32% after three training sessions. When applied to actual operational engineering datasets, the 18-input PSO-BPNN diagnostic model effectively adapts to various scenarios, achieving a diagnostic accuracy of 100.00%. This study provides a novel approach for pipe burst fault diagnosis in long-distance water conveyance systems.

In order to address the cavitation phenomenon and resonance problem caused by unsteady flow in V-type regulating ball valves in the coal chemical industry, the cavitation characteristics of its typical opening were investigated based on computational fluid dynamics, revealing the time-frequency domain characteristics of its pressure pulsation response, and its vibration characteristics were studied using thermal-fluid-structure interaction modal analysis. The results show that the severe cavitation area of the V-type regulating ball valve is located at the throttling part of the ball′s V-port and the diffuser hole of the rear valve seat. When the pressure difference between the inlet and outlet of the valve increase, and the cavitation distribution range as well as the gas phase volume fraction inside the valve also increase. The main frequency and amplitude of the pressure pulsation within the valve are concentrated in the low-frequency region(0-100.00 Hz), and the smaller the opening, the wider the frequency domain of the pulsating pressure energy distribution. There are two main frequency peaks at the 30% opening. The main frequency in the low-frequency region corresponds to the frequency of large-scale cavitation clusters falling off, while the main frequency peak near 287.00 Hz corresponds to the frequency of small-scale cavitation clusters and collapsing. When resonance occurs, the maximum modal deformation of the ball valve is located at the pneumatic device, and the amplitude is greater than 7 mm. The ball shows two sets of amplitude peaks between 45.00-120.00 Hz and 266.25 Hz. The frequency of its amplitude mutation point corresponds to the intrinsic frequency of the valve, and is located in the pressure pulsation main frequency region, which can easily cause large-amplitude vibrations in the pipeline system. In addition, when the ball resonates, its oscillation amplitude is large, which easily causes frequent impacts and collisions with the valve seat sealing surface. This exacerbates the fretting wear between the sealing surface and the ball and easily leads to sealing leakage problems.

Taking into account the impact of tangential freezing/frictional resistance at the contact interface between frozen soil and lining plate, which is induced by the pushing force at the toe-end of the slope plate, the effect of tangential freezing force was introduced into the governing differential equation for frost-heaving deformation of lining plate. A calculation method for analyzing the frost heave mechanism of trapezoidal canals was proposed, based on the elastic frozen soil foundation beam theory, which considers the combined action of frost-heaving force and tangential freezing force. A criterion for judging frost-heaving failure was also proposed. The method can be seamlessly integrated with the natural frost-heaving deformation of the channel foundation soil calculated according to current code of practice. A simplified approach for calculating the pushing force exerted on the toe-end of slope lining plate was proposed based on fundamental principles of engineering mechanics. Based on engineering examples, the frost-heaving deformation of the channel linings was calculated using the proposed me-thod in this paper, as well as traditional and finite difference methods. A comparative analysis was conducted between the calculated values and observed values through an engineering example. The results indicate that the calculated results obtained through the presented method in this paper are generally consistent with those derived from traditional and finite difference methods in terms of trend changes, while also being closer to observed values in terms of magnitude compared with the traditional method. Eventually, the influence of the pushing force on the bending moments of each section of the channel lining was investigated. The findings indicate that the distribution of sectional moment can be influenced by the pushing force applied to the toe-end of the slope plate, as it determines the distribution of tangential freezing force. When the pushing force is greater, the maximum sectional moment also increases to some extent. Neglecting the tangential freezing/frictional resistance would result in a smaller and less secure calculated section moment. The location of the maximum bending moment section is approximately 20% of the slope plate length from the toe of the slope, which is in good accor-dance with the findings derived from on-site investigation. The study can provide reference for the anti-frost design of trapezoidal channels in cold regions.

With increasing global attention on the development of wind energy resources, ensuring the safe and stable operation of wind turbines has become crucial for the efficient utilization. However, extracting information from complex vibration signals units for fault feature characterization faces many challenges. For this reason, a feature extraction method based on the fractional order idea was proposed to improve the feature extraction capability of wind turbine unit signals under different states. Conside-ring the fractional-order characteristics of signals, the extraction effect of complex signal features was improved by introducing the fractional-order cosine similarity entropy(FCSE)method. Meanwhile, the multi-strategy improved grey wolf optimization algorithm(BGWO)was combined to find the optimal parameter combinations of least squares support vector machine(LSSVM)for efficient feature classification. Noise with a signal-to-noise ratio of 3 dB was added to the original signal, and FCSE was compared and analyzed with two traditional feature entropy to evaluate its anti-noise performance. The si-mulation results show that the feature extraction ability of FCSE on a given dataset is significantly better than that of the other two methods, while the classification accuracy of the proposed fault diagnosis system on the laboratory dataset and actual vibration signals reaches 100.0% and 97.50%, respectively, proving its validity and reliability in practical applications.

To reveal the spatiotemporal evolution patterns and driving factors of precipitation and refe-rence evapotranspiration in Xinjiang, the spatiotemporal differentiation characteristics and driving effects of precipitation and reference evapotranspiration based on observational data from 66 meteorological stations in Xinjiang from 1951 to 2020 were systematically analyzed. The results show that spatially, precipitation exhibits a pattern of ″rainy mountains, dry basins, wet west, and dry east″, with terrain uplift creating high-value precipitation areas(around 500 mm)on windward slopes, while enclosed basins receive less than 150 mm. The reference evapotranspiration shows a pattern of ″high in the south, low in the north, strong in the east, and weak in the west″, with the southern and eastern regions exceeding 1 650 mm, while the northern region mostly ranges between 600 mm and 900 mm. The overall spatial differences are primarily driven by the contrast between dry and wet climates, the Tianshan mountain range′s terrain obstruction, and the combined effect of wind power interactions. Temporally, the multi-year average annual precipitation is 177 mm, with a significant increase of 0.52 mm/a after 1982. Reference evapotranspiration decreases by 1.72 mm/a before 1990 and then shifts to an increasing trend of 3.56 mm/a after 1991. The water-heat synchronization exhibits clear seasonal patterns, peaking simultaneously in summer. Significant spatial heterogeneity exists in the water-heat coupling. The strong negative correlation in northern Xinjiang reflects the inhibitory effect of precipita-tion on evapotranspiration, while the weak correlation in southern Xinjiang suggests that this extremely arid region has approached an ecological regulation threshold. This study reveals the multifaceted dri-ving effects of terrain, circulation, and radiation on precipitation and reference evapotranspiration in Xinjiang, providing a scientific basis for optimizing regional water resource management.

To achieve precise control of electrical conductivity in integrated water-fertilizer systems, a fuzzy neural network PID(FNN-PID)control method based on an improved Grey Wolf Optimizer(GWO)was proposed. This method combines the strong fault tolerance of fuzzy control, the adaptive learning capability of neural networks, and the global optimization advantage of the GWO algorithm to enhance system control performance and adaptability. To verify the control effectiveness, a simulation model of the water-fertilizer mixing system was established in the MATLAB/Simulink platform, and four controllers were designed for comparative analysis: the GWO-improved FNN-PID(GWO-FNN-PID), a FNN-PID, a fuzzy PID(FUZZY-PID), and a conventional PID. Comparative analysis was conducted through step response and anti-disturbance tests. The results show that the GWO-improved controller achieves a step response overshoot of only 1% and a settling time of 14.2 s. Under a 20% disturbance condition, its overshoot is controlled within 6% and the settling time is controlled within 6.0 seconds, demonstrating excellent dynamic response and anti-disturbance capability. This research provides an effective control strategy for precise water-fertilizer management and is of positive significance for improving fertilizer utilization efficiency, as well as promoting sustainable agricultural deve-lopment.〓