The motion characteristics of large particles in a vertical pipe under different flow rates were investigated on a closed-loop test rig. Meanwhile, the wear characteristics of the impeller when the pump was transporting solid-liquid two-phase flow were analyzed. High-speed photography techno-logy was employed to capture the motion images of particles in the transparent pipe section, and para-meters such as the motion trajectory, axial velocity, and radial velocity of the particles were analyzed. Moreover, the wear mechanism of the impeller was further explored by applying paint to its surface and documenting the paint detachment at various time intervals. The research results indicate that as the flow rate increases, both the average axial velocity and the average absolute radial velocity of the particles within the vertical pipe exhibit an upward trend, while the velocity difference between the particles and the fluid gradually decreases. Impeller wear initially occurs at the leading edge of the blades and progressively extends to the front cover, rear cover, and the blades over time, with the rear cover experiencing the most significant wear. Within the impeller, the Coriolis force plays a dominant role in influencing the motion characteristics of the particles compared to the centrifugal force, causing the particles to preferentially move along the pressure side of the blades, which results in more pronounced wear.

The applicability of high-dimensional hybrid modeling for submersible pump impeller optimization and the influence of weighting coefficients were investigated using a specific-speed-87 submersible pump.Optimization was performed based on a constructed SVR-HDMR model coupled with a genetic algorithm. The impact of varying head and efficiency weighting coefficients on internal flow characteristics and impeller outlet velocity was analyzed through multi-objective optimization. Computational results were experimentally validated, with all errors found to be around 5%. The results show that pump performance is enhanced by all three optimization schemes. The optimal solution, employing equal weighting(0.5)for both head and efficiency,results in reduced internal flow losses, mitigated flow disorder, an incrased circumferential component of the absolute velocity at the impeller outlet, and decreased turbulent kinetic energy. Consequently, the pump′s head and efficiency are effectively improved. At the design operating point, an efficiency increase of 1.80% and a head gain of 1.20 m are achieved by the optimized pump. This study provides a valuable reference for the design of guide vane centrifugal pumps.

To enable timely crack detection in hydraulic turbine runner blades, ensure unit health monitoring, and enhance operational safety, an intelligent fault diagnosis method was proposed based on computational fluid dynamics(CFD), rime optimization algorithm(RIME), variational mode decomposition(VMD), and long short-term memory(LSTM)neural network. First, the flow field was simulated using CFD, and the results were imported into finite element analysis(FEA)software through fluid-structure interaction to obtain time-domain vibration signals for both healthy and cracked runner blades. Subsequently, the modal component number(K)and penalty factor(α)of VMD were optimized by RIME. The optimized VMD was then employed to decompose the vibration signals into multiple intrinsic mode components. Finally, these components were fed into the LSTM neural network for feature extraction and fault identification. The results demonstrate that the proposed method eliminates the economic costs associated with physical crack sample acquisition, significantly reduces the development cycle, and achieves highly accurate blade crack detection. For radial and axial vibration signals, the overall fault recognition accuracy reaches 93.033 0% and 92.893 9%, respectively.

A numeriacal simulation method combining computational fluid dynamics(CFD)and the Ffowcs Williams-Hawkings(FW-H)equation was established to predict the noise mechanism of a multi-blade centrifugal fan in a bathroom heater. The aerodynamic performance, pressure pulsastion characteristics, and aerodynamic noise of the fan were analyzed. The structure of the fan heater was optimized to improve the aerodynamic performance of the fan and reduce noise. In terms of the impeller, the impeller flow channel structure was optimized by improving the inlet angle, outlet angle and total number of impeller blades. In the static domain, the bending sections of the volute and the outlet section were eliminated, the internal baffle′s length of the outer was increased, and the clearance of the volute was enlarged. The research results reveal that the optimized model exhibits better performance in terms of flow field characteristics and impeller work range, concurrently leading to a reduction in the noise pressure level across the entire frequency range. The experiments have confirmed that the average sound pressure level of far-field noise in the optimized model is 3.11 dB lower than that of the original model, which further affirming the reliability of the optimization scheme.

To improve the adverse flow pattern in the forebay of a large pumping station drawing water from a sandy river, a typical pump station of the Jingtai River Diversion Power and Irrigation Project in Gansu Province was selected as research object. A three-dimensional model of the forebay with varying side wall contraction angles was constructed, and numerical simulations were conducted using Fluent software, based on the realizable k-ε model and the mixture multiphase flow model. The simulations yielded the flow field structure and changes in water flow velocity with variations in the side wall contraction angle. The results show that after water enters the forebay from the channel, it rapidly turns due to the suction from the pump units, forming a divided flow field structure in the lateral forebay. A high-velocity mainstream area forms in the center of the forebay, with vortices of varying sizes on either side creating low-velocity recirculation areas. As the side wall contraction angle increases, the linear motion distance of the water increases, the deflection angle decreases, and the flow development and diffusion effects along the flow path are enhanced. The area of the mainstream zone significantly increases, while the recirculation zone area and vortex size are markedly reduced. At a side wall contraction angle of α=5°, the overall uniformity is improved by 5.58% compared to the original project pump station, effectively mitigating sediment accumulation problems in the forebay of a pump station drawing water from a sediment-laden river. These research findings can provide guidance and reference for the design and retrofitting of similar pump stations.

In order to evaluate the impact of the hump characteristics in the pumping area on the hydraulic transients during the pumping trip condition in pumped storage power stations and guide the selection of pumped-storage units, a hump deflection index was proposed to intuitively and quantitatively evaluate the strength of the hump characteristics of a pump-turbine. The complete characteristic curves of the pump-turbine were adjusted by changing the hump angle, and the effect of different hump angles on the maximum pressure at the spiral case end and the minimum pressure at the draft tube inlet were analyzed using the method of characteristics. The results show that the smaller the hump angle, the smaller the maximum pressure at the spiral case end and the greater the minimum pressure at the draft tube inlet when the pumping trip occurs, and the more favorable the extreme value indexes of the regulation guarantee parameters. As the hump angle increases, the slope of the hump area becomes steeper. A small change in the unit speed can also cause rapid changes in the flow rate and torque of the unit, leading to strong pressure pulsation. Therefore, it is advisable to choose a pump-turbine with a small hump deflection angle to reduce the amplitude of pressure pulsation and ensure the safe operation of pumped storage power stations under pumping conditions. The research results can provide a refe-rence basis for the selection of units and the optimization design of pump-turbines in pumped storage power stations.

In order to investigate the splitting tensile properties of steel basalt fiber reinforced concrete(BFRC)and its deterioration rule under salt freezing conditions, three types of steel fiber BFRC(hook type, wave type, and copper-coated type)were prepared with the steel fiber volume contents of 0.8%, 1.0%, and 1.2%, respectively. By comparing the splitting tensile strength of the test blocks, the optimal group was selected for freeze-thaw cycle tests under salt freezing conditions. Combined with mass loss rate, relative dynamic elastic modulus, and nuclear magnetic resonance(NMR)test, the deterioration mechanism of concrete was analyzed. The freeze-thaw damage model of steel-basalt fiber reinforced concrete was established by a multiple regression analysis equation. The results show that the incorporation of steel fibers increases the concrete splitting tensile strength and frost resistance life. Among them, the end-hooked steel fiber BFRC with 1% by volume admixture has the highest split tensile strength and frost resistance, which are 66% and 40% higher than the baseline group. The fitting equations for splitting tensile strength, proportion of harmful pores, saturation of bound fluid, and number of freeze-thaw cycles are established by multiple linear regression, the prediction accuracy is high with an average relative error of only 2.88%.

To achieve water-saving irrigation and effective evaluation of water stress in greenhouse tea seedlings, one-year-old ″Suchazao″ tea plants were selected as experimental material. Non-stressed control(NS), mild(LS), moderate(MS)and severe(SS)water stress treatments were established. The changes in gas exchange parameters, chlorophyll fluorescence parameters, water potential(ψ_w), and leaf relative water content(RWC)are systematically investigated under different water conditions. The results show that as water stress intensifies, significant decreases were observed in net photosynthetic rate(Pn), stomatal conductance(Gs), and transpiration rate(Tr), while intercellular CO₂ concentration(Ci)remains stable. Water potential(ψ_w)decreases significantly with increasing stress levels. No significant difference is detected in the actual quantum yield of PSⅡ(YII)between NS and LS treatments. However, significant reductions are observed under MS and SS treatments. The maximum photochemical efficiency of PSⅡ(F_v/F_m)gradually decreases with stress severity, with no significant difference between LS and MS treatments.The photochemical quenching coefficient(qP)and quantum yield of non-regulated energy dissipation Y(NO)initially increase and then decrease with stress progression. In contrast, the non-photochemical quenching coefficient(qN)and quantum yield of regulated energy dissipation Y(NPQ)first decrease and then increase. All parameters except Y(NO)and Ci show significant positive correlations with water availability. Among different stress le-vels, water potential(ψ_w)is identified as the most sensitive indicator. Other parameters exhibit varying sensitivity: Pn, Y(NPQ)and qN are most responsive to mild stress, Tr, Pn and Gs show higher sensitivity to moderate stress, while Tr and Gs demonstrate the strongest response to severe stress. These indicators can serve as diagnostic criteria for different water stress levels.

To explore the effects of rotation irrigation mode with saline-freshwater on tomato growth and development, soil nutrients and salt ions characteristics in arid and semiarid agricultural areas, ″fresh-fresh-saline-saline″(T1), ″saline-saline-fresh-fresh″(T2), ″fresh-saline-saline-fresh″(T3), ″fresh-fresh-saline-saline″(T4), ″fresh-saline-fresh-saline″(T5), ″saline-fresh-saline-fresh″(T6)six irrigation methods were set up during the key growth period of tomato, and a two-year field experiment was carried out. The results indicate that the saline-freshwater rotation irrigation me-thod can save 30.0%-66.7% of freshwater compared with traditional freshwater continuous irrigation during the tomato growth period. The ″fresh-fresh-saline-saline″ rotation irrigation method is more conducive to reducing soil nitrogen loss in the taproot layer of tomatoes.The soil salt cation and anion contents increase with the increase of saline water irrigation amount. Under the lower limit of soil matrix potential control of -25 kPa, the rotation irrigation of saline-freshwater during the tomato growth period results in salt accumulation in the surface 40 cm inside and outside the film as well as(40,100］ cm inside the film, and the salt content of the surface 40 cm inside the film for the rotation irrigation modes increases by 7.8%-67.2% compared with the traditional freshwater irrigation. Compared with traditional freshwater irrigation, saline-freshwater rotation irrigation significantly reduces the weight of single tomato fruit, with the tomato yields decreasing by 1.9%-18.3%, while the fruit lycopene content and total sugar content increase by 6.2%-18.5% and 4.8%-15.2%, respectively. Dramatically, the ″fresh-fresh-saline-saline″ mode achieves the maximum tomato yield, highest lycopene content and maximum total sugar content. Therefore, it is suggested that in the Hetao Irrigation District of Inner Mongolia, the best rotation irrigation method of saline-freshwater for tomatoes under film drip irrigation is ″irrigation with Yellow River water from the seedling stage to flowering stage″ and ″irrigation with shallow groundwater from fruit setting stage to fruit expansion stage″.

In order to solve the key technical problems of efficient water-saving irrigation and water-fertilizer integration equipment promotion in Ningxia Yanghuang Irrigation District, the effects of different irrigation equipment on the growth of daylily and the physicochemical properties of the soil to obtain the optimal selection of irrigation equipment were analysed. Four treatments with different irrigation equipment and one control were set up in the experiment to comprehensively analyze the effects of different irrigation equipment on the growth indexes of daylily and soil physicochemical properties using the entropy weight TOPSIS model. The results show that different irrigation equipments have a significant effect on nutrients, as well as the yield and its constitutive factors before and after planting in the daylily planting site. The optimal treatment reduces soil pH by 0.45 and salinity by 14% relative to the CK treatment, increases nutrient uptake of nitrogen, phosphorus and potassium in daylily by 18%, 17%, and 15%, and increases the thickness of daylily flower shoots by 11%, the length of buds by 11%, and the thickness of buds by 6%, respectively. Meanwhile, the daylily weight TOPSIS method is used to establish a comprehensive evaluation system for daylily, and the intelligent portable rechargeable fertilizer applicator is obtained as the optimum with a comprehensive response score of 0.952 9. Therefore, the use of a smart portable rechargeable fertilizer applicator can promote the absorption of water nutrients, as well as the growth and development of daylily.

To enhance the accuracy of safety diagnostics and pressure monitoring in large-scale micro-irrigation networks while reducing the number of monitoring points, an adaptive algorithm for optimizing the placement of pressure monitoring points in large-scale micro-irrigation networks was proposed. Firstly, range standardization was applied to the initial node pressure data of the water supply network, and the optimal number of monitoring points was then adaptively determined using the sum of squared errors(SSE)method. Finally, different clustering algorithms were employed to identify the optimal monitoring point placement scheme. The results indicate that as the number of monitoring points increases, the SSE value decreases rapidly at first and then gradually slows down. The inflection point on the curve is identified as the target number of monitoring points. The average silhouette coefficients for the three main pipelines under the target algorithm are 0.400 89, 0.518 18, and 0.410 21, representing improvements of 15.3%, 2.5%, and 2.4%, respectively, compared to the baseline algorithm. This method ensures the economic efficiency and reliability of the number of monitoring points, as well as the accuracy of their placement, providing a theoretical foundation and methodological guidance for the optimization of pressure monitoring points in large-scale micro-irrigation network systems.

In order to study the influence of the key spray plate structure of low-pressure fixed-refractive sprinkler on the distribution characteristics of spray water droplets, the number of grooves, inclination angle of groove and cone angle of spray plate were designed, and the spray droplet distribution characteristics of low-pressure fixed-refractive sprinklers with different spray plate structure parameters were tested by video droplet spectrometer through orthogonal tests. The effects of the spray plate structure parameters on the spray droplet distribution characteristics of low-pressure fixed-refractive sprinkler were revealed. The results show that increasing the deflector cone angle effectively reduces the droplet diameter and improves the uniformity of the distribution. Meanwhile, the larger groove inclination angle and the number of grooves shift the peak droplet diameter backward, which affects the distribution range of droplet size. In addition, the deflector cone angle significantly affects the droplet velocity and individual droplet kinetic energy in the mid-range, while the number of grooves and groove inclination mainly affect the droplet velocity at the front and end of the range, and lead to the formation of larger individual droplet kinetic energy. Therefore, the size, velocity and kinetic energy distribution of water droplets can be improved by adjusting the spray plate structure parameters, which provides a theoretical basis for the design of high-efficiency irrigation sprinklers.