To address prevalent issues related to water resource wastage and the limited scope of irrigation and drainage planning and design in contemporary agricultural irrigation regions, and to effectively advance the standardization of the design process for irrigation and drainage planning, a theoretical study on agricultural adaptation was undertaken. This study was grounded in the specific context of the rice irrigation area in Yaoqiao Town, Zhenjiang City, Jiangsu Province, utilizing a bidirectional flow channel pumping station as a case study. The feasibility and effectiveness of bidirectional flow channel pumping stations mainly applied to large and medium-sized water conservancy facilities in agriculture were explored. A water supply and drainage planning and design mode suitable for rice agriculture in this irrigation area were given, and a suitable irrigation and drainage design and planning program was given. Two neighboring paddy fields were selected for actual planting comparison, with ordinary pumps and bidirectional flow channel pumping stations for irrigation and drainage operations, respectively. The results of irrigation and drainage experiments show that the bidirectional flow channel pumping stations planning in paddy fields can increase the yield of rice under each growth cycle by 4.76%. Compared with ordinary pumps, the power energy of the pump station can save 7.2% in electricity, achieving a comprehensive water-saving effect of 12.2%. The average integrated benefits of the paddy fields served per hectare increase by more than 3 420 yuan. Significant emphasis is placed on the critical role of preparatory work prior to the planning and design of irrigation and drainage systems. Utilizing a comprehensive assessment of the project area, a scientifically grounded and rational design analysis is performed for the irrigation and drainage engineering.

In order to improve the cavitation performance of low-specific speed centrifugal pumps, an impeller model featuring a tandem blade structure was designed. The transient numerical analysis of centrifugal pump employed a modified SST k-ω turbulence model in conjunction with Z-G-B cavitation model. The algorithm was verified by hydraulic characteristic test and cavitation test. A comparative analysis was conducted between the original model and the tandem blade impeller model, focusing on hydraulic characteristics, cavitation characteristics, flow field structure, pressure distribution, turbulent energy distribution, cavity volume, and pressure pulsation. The results show that the tandem blade structure exerts minimal influence on the hydraulic characteristics of the centrifugal pump. However, it effectively suppresses air bubble formation during the development and serious stages of cavitation, thereby enhancing the pump′s cavitation performance. Simultaneously, it inhibits the expansion of the high turbulence kinetic energy region during the initial phase of cavitation, diminishes the intensity of turbulence kinetic energy at the impeller outlet throughout the development and advanced stages of cavitation, and mitigates the formation of low-pressure areas surrounding the rotating impeller. Mitigating the primary frequency amplitude of pressure pulsations at the tongue of the snail shell during both the development and advanced stages of cavitation can effectively suppress the noise and surge associated with cavitation, thereby enhancing the operational stability of the pump.

In order to explore the change law of internal pore structure of mixed sand concrete under accelerated sulfate attack under different environmental conditions, the experimental study on sulfate attack mixed sand concrete under initial injury, mix salt, freeze-thaw cycle, dry-wet cycle, multiple concentrations and high temperature environmental conditions shows that the effect of sulfate attack on the change law of internal pore structure of mixed sand concrete under different environmental conditions is different. With the increase of erosion period, the proportion of harmless pores and less harmful pores under other conditions shows a decreasing trend except that the harmless pores under multiple concentration and composite salt conditions show a slight increase. Compared with the control group, the proportion of harmless holes decreases under the conditions of multiple concentration, initial damage and freeze-thaw cycle, while the proportion of harmless holes increases under the conditions of compound salt, high temperature and dry-wet cycle. The proportion of harmful holes increases significantly under the conditions of initial damage and high temperature, while the proportion of harmful holes decreases under the other conditions. Compared with the control group, the porosity increases by 32 % under the condition of dry-wet cycle, the average pore diameter increases by 3 255.4% under the condition of multiple concentration, and the increase of bound fluid saturation damage and free fluid saturation under the condition of initial damage was the largest.

The start-up process of a mixed-flow pump was optimized using ANSYS Workbench in conjunction with OptiSLang optimization design software. Utilizing quasi-steady state theory and full-domain model calculation data, a response surface surrogate model for the hydraulic performance during the quasi-steady start-up process of the mixed-flow pump was established. The internal flow state was optimized and the vortex-induced energy losses was reduced during the start-up process by using the NSGA genetic algorithm, and thus enhancing the hydraulic performance of the mixed-flow pump. The hydraulic characteristics and blade pressure distribution of the original and optimized mixed-flow pumps were compared, and the internal vortex structure was analyzed, and the feasibility of the proposed hydraulic performance optimization scheme for the quasi-steady start-up process was verified. The research results indicate that the blade inlet angles α₁, α₄, α₅, outlet angles β₁, β₂, β₃, β₄, β₅, blade wrap angle φ, and blade thickness coefficient θ have a significant impact on the weighted average head and weighted average efficiency of the mixed-flow pump. The blade pressure distribution at diffe-rent start-up times was compared, it was found that this method can effectively improve the transient head in the middle and late stages of start-up process.

In order to reveal the evolution of the internal vortex structure in a mixed-flow water jet propulsion pump under cavitation conditions, the Ω vortex identification method was used to identify and study the internal vortex structure under a cavitation number of 0.142. Based on this, the influence of cavitation on the characteristics of vortex structure was investigated, and the contributions of various terms in the vorticity transport equation to the evolution of vortex structure during one cycle were analyzed. The results show that under cavitation conditions, the internal flow of the water jet propulsion pump is complex, and it is extremely prone to generating vortices. The main vortex structures include blade tip leakage vortex, secondary leakage vortex, vertical cavitation vortex, and secondary leakage-derived vortex. As the triangular cavitation collapses, the scale of the inlet attached vortex increases, but the vorticity of the tip leakage vortex gradually decreases due to the increasing size of the cavitation bubble. During one cycle, when the scale of the cavitation bubble in the water jet propulsion pump is relatively large, the scale of vortex structure is large, but the intensity is small. When the scale of the cavitation bubble is small, the scale of the vortex structure decreases and the intensity increases. Through the decomposition of the vorticity transport equation, it can be found that the distribution of the stretch-twist term is highly similar to the distribution of vorticity, and the compression-expansion term has the highest magnitude, which is closely related to the scale of the cavitation bubble and is sensitive to the changes of the vertical cavitation vortex and the shedding vortex. The magnitude of the oblique pressure moment term is higher at the location of the vertical cavitation vortex.

Based on the integrated device of peristaltic pump for preparing and injecting fertilizer, the problem of reduced precision in fertilizer dispensing and injection caused by reflux phenomenon during the operation of peristaltic pump was studied. The structure of slipper in peristaltic pump for the problem that the precision of fertilizer distribution and injection was carried out, the hydraulic performance was tested to reveal the influence law of key structural parameters on fertilizer distribution flow, pump pipe temperature, instantaneous flow and reverse flow coefficient. The results show that under the same pump speed conditions, with the increase of slipper radius, the flow rate of fertilizer distribution decreases gradually, while the temperature of pump tube gradually increases. At the radius of 37.5 mm, the maximum value of 51.3 ℃ is reached, and the average reverse flow coefficient decreases first and then increases, reaching a minimum value of 0.56 at a radius of 30.0 mm. Under the same slipper radius conditions, with the increase of the rotation speed, the fertilizer distribution mixing flow rate increases gradually, and the instantaneous flow rate shows a trend of first increasing and then decreasing. The temperature of the pump tube rises sharply at first and then tends to be stabilize, while the reverse flow coefficient shows a trend of first decreasing and then increasing and then decreasing. The optimal radius of slipper is calculated as 30.0 mm by means of comprehensive score method and entropy weight method. In the end, it is suggested that the 30 r/min speed of peristaltic pump should be set in irrigation system. The experimental results can provide ideas for the research on improving the precision of fertilization in the integrated device of water and fertilizer.

Aiming at the difficulty of controlling the surface roughness of thin-walled titanium alloy impeller blade of centrifugal pump and the abrasion of the blade surface by gravel in the process of use, the TC4 titanium alloy surface with high roughness after milling was polished by using a nanosecond pulse laser under argon and air atmospheres, respectively. It is found that a better polishing effect could be obtained under argon atmosphere, which can reduce the surface roughness of the workpiece by 56.12% and the surface hardness increases by 21.94%. In the air atmosphere, high hardness of titanium nitride is obtained on the workpiece surface, and the surface roughness decreases by 51.89% and the hardness increases by 176.79% when compared with the original surface. The frictional wear test results show that both the original surface of the workpiece and the surface of the workpiece po-lished under argon atmosphere are mainly dominated by abrasive wear. Among them, the workpiece po-lished under argon atmosphere has a narrower width of abrasion marks due to the higher hardness α′-Ti martensite is obtained during the polishing process. Under air atmosphere, due to the high hardness titanium nitride obtained from the remelting layer. the average dynamic friction coefficient of the workpiece surface decreases from 0.46 to 0.16. This significantly improves the wear resistance of the workpiece surface and reduces the width of the abrasion marks. During the grinding process with GCr15 ceramic balls, the workpiece surface mainly exhibits adhesive wear.

To investigate the axial displacement balance and axial force characteristics of the rotor system in a turbine-type energy recovery integrated machine, the Reynolds-Averaged Navier-Stokes(RANS)method was employed, utilizing the SST k-ω turbulence model to perform a numerical simulation of the entire flow field within the integrated machine. The impact of varying axial clearance sizes on the hydraulic performance of the machine was analyzed. Additionally, the internal flow characteristics and axial force variations were examined across five different axial clearance configurations. The findings indicate that the magnitude of axial clearance exerts a substantial influence on the leakage flow at the turbine end. An augmentation in axial clearance results in a maximum reduction of 8% in turbine end efficiency. Conversely, the hydraulic performance at the pump end is minimally impacted and remains largely stable. Under rated design conditions, an increase in axial clearance leads to a reduction in the average pressure within the front chamber of the turbine end by 0.37 MPa. The axial force of the integrated rotor system is directed towards the turbine end, and the magnitude of this axial force increases by about 5 kN. The research results can provide theoretical guidance for the design and operation of turbine energy recovery integrated machine.

Based on Lighthill′s acoustic analogy theory, a hybrid numerical simulation method was used to analyze the influence of flow variation on the frequency domain characteristics of sound pressure level(SPL)and overall sound pressure level(OSPL)of flow-induced noise in shaftless pump-jet propulsor and its relationship with the internal flow field. The results indicate that the axial passing frequency(APF)is the main frequency, with a high peak at 2 APF. At small and design flow rate, the SPL at APF exhibits an initial decrease, followed by an increase, and then another decrease along the flow direction. While it shows an initial increase followed by a subsequent decrease radially, and there are blade passing frequency(BPF)and its harmonic frequencies in the frequency spectrum. However, the SPF decreases along the flow direction, and decreases first and then increases along the radial direction at large flow rates without BPF and its harmonic frequencies in the frequency spectrum. Meanwhile, as the flow rate increases, the SPL at APF near the impeller gradually increases. While for the case of distant regions, it exhibits an initial increase followed by a subsequent decrease. The OSPL is found to increase as the flow rate increases. Along the flow direction, the OSPL decreases gradually, with a lower rate of noise attenuation rate at large flow rates. The highest OSPL approaches the axis radially with the increase of the axial distance of the radial region. The velocity gradient and the variation of the two vortices in the outlet section near the impeller are the main factors affecting the noise distribution of the shaftless pump-jet propulsor at different flow rates.

In order to improve the uniformity of the combination sprinkler irrigation with the vertical impact sprinkler, the PY₂20 vertical impact sprinkler was added deflectors in the inner space of the nozzle. The shape parameters of deflector including the length, the transverse curvature and the longitudinal curvature were taken as experimental factors to carry out the hydraulic performance test. The nonlinear mapping model analyses of the optimal shape parameters of the deflector was constructed. The BP neural network algorithm was used to solve, and the hydraulic performance, and the optimal structural parameters of the sprinkler deflector were obtained. The results show that the length of the deflector has a very significant effect on the wetted radius, while the transverse curvature and longitudinal curvature have little effect. The distribution of the point sprinkling irrigation intensity of sprinkler nozzle with deflector in the radial direction is more uniform than that of sprinkler nozzle without deflector,which shows a trend of gradual decrease at first,and then gradual increase. Under the condition of square combination for sprinkler with deflector, when the length of the deflector is greater than 2 mm, the uniformity of sprinkler irrigation system is significantly higher than that of the original sprinkler. The length of the deflector has a significant impact on the uniformity of sprinkler irrigation system, but the effect of the transverse curvature and longitudinal curvature are not significant. Considering both the maximum uniformity of sprinkler irrigation system and the farthest wetted radius, the most optimal deflector parameters are that length is 3 mm, transverse curvature is 1.5 mm and longitudinal curvature is A/3. The final wetted radius is 19.09 m and the uniformity of sprinkle irrigation system is 89.38%. The research results are of great significance for improving the utilization efficiency of water resources in sprinkler irrigation.

An optimization method was proposed in this study for centrifugal pump impeller blade loa-ding using the 3D inverse design. A medium-specific speed centrifugal pump was selected as the research object, and the impeller blades with front-loading shroud and after-loading hub were redesigned using the 3D inverse problem design method without changing its axial projection, blade thickness distribution, and other conditions. The Latin hypercube sampling method was used to establish a sample space of 80 centrifugal pump impeller models, and the centrifugal pump performance was obtained by numerical simulation using Fluent software. By taking the blade loading parameters as the optimization object and the hydraulic efficiency of the centrifugal pump design operating point as the optimization target, the relationship between the blade loading parameters and hydraulic efficiency was established using the Kriging surrogate model. Under the condition that the head met the design requirements, the MIGA algorithm was used to obtain the load parameters of the centrifugal pump with the highest hydraulic efficiency. The results show that in the loading curve, the parameters that have a greater influence on the efficiency are the two intersection points ND_h and NC_h of the straight line and the parabola in the hub, and the intersection point NC_s of the straight line and parabola in the shroud. The parameters with less influence are the leading edge loading LE_h in the hub and the intersection point ND_s of the straight line and the parabola in the shroud. The hydraulic efficiency of the optimized centrifugal pump is increased by 1.35% at the design working point and the efficiency zone is wider. The minimum pressure on the surface of the blades is increased by 38.41% and the cavitation performance is improved. In addition, the power is reduced by 2.46% and the head is slightly improved. The study results provide a useful reference for the efficient design of impeller blades of centrifugal pumps.

According to the theory of unidirectional fluid structure coupling, the fluid pressure data, derived from simulations of the fluid pressure experienced by the blade at different rotation angles, were utilized as the boundary condition for structural analysis and subsequently incorporated into the finite element analysis model for further examination. The structural design of waterwheel blades was conducted using epoxy S-glass fiber and epoxy E-glass fiber materials. The influence of different layer laying angles in the composite materials on the mechanical properties of waterwheels was explored, aiming to determine the optimal layering scheme. Furthermore, the structural analysis results of the composite blades were compared with those of blades with a solid structure. The results indicate that the application of epoxy E-glass fiber material, combined with a layer stacking scheme with a layer layup angle θ=15°, has the most significant improvement in the structural performance of micro head waterwheel blades. In comparison to solid steel blades under the same operating conditions, the maximum deformation of composite blades is reduced by 53.4%, thereby effectively alleviating the phenomenon of stress concentration. Additionally, the mass of composite blades is greatly reduced, achieving a weight reduction effect of 80.7%. These results provide a theoretical basis for the safe and efficient design of micro head waterwheel blades.

The structure configuration and parameters of the fertilizer absorber have a significant influence on the working performance of the intelligent water-fertilizer integrated machine system. Aiming at the problems of low fertilizer absorption capacity and high pressure loss of common fertilizer absorbers, three SSQ jet fertilizer absorber devices, two combined jet fertilizer absorber and one venturi fertilizer absorber were selected for analysis. The absorption performance of six kinds of fertilizer absorbers was evaluated under different inlet pressures and inlet-outlet pressure differences by means of experiments and numerical simulation, and the structure of fertilizer absorber with better performance was optimized and studied through orthogonal and range analysis. The results show that under the same working conditions, the comprehensive performance of the SSQ jet-type fertilizer injectors is superior to that of the combined jet-type and Venturi injectors, and the maximum fertilizer absorption flow, working range(p₁=0.30 MPa)and maximum fertilizer absorption efficiency of jet fertilizer absorber are increased by 71.75%-102.66%, 38.40%-48.29% and 42.57%-93.24%, respectively, and the critical pressure difference is reduced by 9.09%-35.43%. The fertilizer absorption efficiency of SSQ-3 jet fertilizer absorber first increases and then decreases with the increase of throat nozzle area ratio and throat nozzle distance, and gradually decreases with the increase of tapering section angle and widening section angle. The optimal structural parameters of SSQ-3 jet fertilizer absorber are throat nozzle area ratio of 2, widening section angle of 5°, tapering section angle of 9° and throat nozzle distance of 5.94 mm. After structural optimization, the fertilizer absorption flow and efficiency of jet ferti-lizer absorber are increased by 9.09%-22.86% and 4.78%-27.43%, respectively.

To address the issue of gas outflow from the outlet of a vacuum tank and to explore the underlying mechanism of gas-liquid two-phase flow within vacuum tank, the RNG k-ε turbulence model and Volume of Fluid(VOF)model were employed. Analyses were conducted on the gas-liquid interface morphology, gas discharge percentage at the outlet pipe, and flow conditions under different initial conditions. The influence of initial conditions on the internal flow field was investigated, and the relationship between water level and internal flow field/outlet pipe characteristics was examined. Results indicate that when the initial water level is significantly higher than the inlet pipe, the internal flow field of the vacuum tank is substantially optimized. Compared with the original initial water level, the interaction at the gas-liquid interface is reduced. The peak gas discharge percentage decreases from 6.916% to 0.106%, with the average value decreased from 3.442% to 0.027%. The flow pattern in the outlet pipe has been significantly improved, and the low-pressure regions at the top has decreased. Research findings demonstrate that variations in initial water level can affecte the flow field characteristics, gas discharge volume, and outlet pipe flow patterns within the vacuum tank, providing data support for a deeper understanding of internal flow dynamics and vacuum water tank design.

The aim of this work is to reveal the effect of the geometric distribution and structural parameters of xylem perforation plates on vessel hydraulic characteristics. By the computational fluid dynamics(CFD)method, the micro-flow mechanism in the vessels with three perforation plates was si-mulated by a k-ε turbulent physical field with a low Reynolds number combined with the Bernoulli equation. The impacts of the inner diameter, the type of perforation plates, as well as their inclination angle, hole number, and equivalent diameter ratio on water transport in the vessel were examined in terms of the pressure difference, the flow resistance coefficient, and the hydraulic conductivity. By comparing with a simple perforation plate, the pressure drop of the vessel with a reticulate perforation plate increases by 44.2%, and the flow resistance coefficient increases by 53.3%. The pressure drop of the vessel with a scalariform perforation plate increases by 76.5%, and the flow resistance coefficient increases by 92.3%. As other parameters are consistent, the pressure difference and the vessel flow resistance are inversely proportional to the vessel inner diameter, the inclination angle of perforation plates, and the equivalent diameter ratio. Meanwhile, the two parameters are proportional to the hole number. Furthermore, the effect of water transfer on the inclination angle of a simple perforation plate is negligible. The hydraulic conductivity of the three vessels is ordered from high to low as follows: simple perforation plate, reticulate perforation plate, and scalariform perforation plate. The larger the inner diameter of a vessel, the higher the hydraulic conductivity.

With the trapezoidal pier-suspended grid combined energy dissipator situated in the stilling basin as the research object, the RNG k-ε turbulence model and VOF method were used for numerical simulation to study the hydraulic characteristics and energy dissipation effect of the trapezoidal pier-suspended grid stilling basin. This was done in order to address the issue of hydraulic jump energy dissipation with low Froude number. The results show that the trapezoidal pier can effectively reduce the floor pressure and the velocity near the bottom of the stilling basin. The pressure behind the pier is lower than 100 Pa, and the velocity decreases to 0.20 m/s. As Fr increases,the effect of improving pressure and velocity distribution becomes more significant. The maximum vorticity magnitude in the stilling basin is located in the hydraulic jump and rolling area on the steep slope, where there is an obvious vortex core, which is the main area of energy dissipation. The vortex structure in the trapezoidal pier and suspended grid area is discontinuous, which belongs to the weak vortex structure and the energy is partially dissipated. The energy dissipation in the trapezoidal pier-suspended grid stilling basin is mainly composed of three parts: hydraulic jump energy dissipation, trapezoidal pier shear dissipation and suspension grid dissipation, and the energy dissipation rate of the three working conditions is increased by 4.49%, 9.74% and 9.79% respectively compared with the traditional stilling basin, which gives full play to the effect of superimposed energy dissipation of joint energy dissipators. The results can provide reference for the design and research of energy dissipators in similar projects.

In response to the current lack of suitable irrigation machinery in hilly slopes, a self-propelled spraying device suitable for hilly slopes was designed based on the characteristics of tea plantation planting and the terrain features of hilly slopes.Mechanical theoretical analysis on common spraying driving conditions such as straight-line driving, longitudinal climbing, and lateral slope walking of the spraying device were performed. The RecurDyn multibody dynamics software was used to model the device and simulate the driving state of the device under common spraying driving conditions. The simulation results show that the device has good straight-line driving and climbing performance, and can smoothly pass through a maximum 15° transverse slope and a maximum 15° longitudinal slope. A prototype was developed and tested on a real machine. The average driving speed of the prototype was measured to be 1.94 km/h, with good straight-line performance, and a driving deviation rate of 2.88%. It smoothly passes through a longitudinal slope with a slope angle of 13°, and safely and stably travels on a transverse slope with a slope range of 8°-13°, which is consistent with the simulation results and meets the requirements for slope operation of self-propelled spraying devices. This provides a reference for the design and research of subsequent hilly irrigation equipment.

Traditional soil modifiers(such as lime, cement, gypsum, fly ash, etc.)have improved the hydraulic-mechanical properties of soils to some extent, but they have as well damaged the environment to some extent. Taking calcium lignosulfonate(hereinafter referred to as lignin)as modifier, pinhole test, fragment test, sodium ion exchange ratio test, boundary water content test, unconfined compressive strength test, direct shear test, permeability test, and nuclear magnetic resonance porosity test were carried out to study the effects of lignin content, dry density, and water content on the disper-sibility and hydraulic-mechanical properties of natural dispersive soil. The results show that when the lignin content is 3% and 4%, the modified soil sample is non-dispersive, and the higher the dry density, the worse the dispersibility. With the addition of lignin, the liquid limit, plastic limit and plastic index of soil samples decrease. When the content of lignin is 2%, the unconfined compressive strength, shear strength, and permeability of soil samples experiences best improvement, but when the content of lignin is too large, the hydraulic-mechanical characteristics of soil samples become worse. T₂ spectrum presents a bimodal structure. With the increase of lignin content, the main peak gradually moves to the right, the small pore size of soil samples becomes larger, and the number of large pore sizes increases.

To understand the influence of wind speed profile distribution determined by atmospheric stability on the operational characteristics of wind farms, a numerical weather prediction model incorporating a coupled wind farm parameterization scheme was developed to investigate the wake effect and the power generation characteristics of large wind turbines within large wind farms under varying atmospheric stability conditions. The results show that wind farm exhibits pronounced wake effects under stable atmospheric boundary conditions. Furthermore, as the atmosphere turns from instability to strong stability, there is a discernible trend of increasing wake intensity. In addition, the mutual interference between upstream and downstream wind farms is significantly more pronounced within a stable atmospheric boundary layer. Under stable boundary conditions, the power output of the wind farm exceeds the average power output by approximately 4%.Conversely, under unstable boundary layer conditions, the power output is reduced by approximately 9% relative to the average power output. Furthermore, surface shear stress and atmospheric stability significantly influence the power output of wind turbines. Under unstable atmospheric boundary conditions, atmospheric stability serves as a critical evaluation parameter for wind power. Consequently, the traditional approach of considering only the impact of wind shear on power output is insufficiently comprehensive.

Axial-flow(tubular)pumps are widely used in the construction of pumping stations such as China′s South-to-North Water Diversion Project and “the Belt and Road Initiative”. In order to study the influence of fluid exciting forces on system vibration of large-scale axial-flow pump under several ope-rating conditions, CFX and Mechanical were combined to conduct the numerical simulation of the fluid-structure coupling, as well as the flow-induced unsteady stresses on the blades of the pump impeller. The fluid domain was resolved based on the N-S equation with the RANS method, and the solid domain was calculated by adopting the dynamic equation of elastic structure. The deformation, stress distribution and modal characteristics of the pump rotor were obtained using the arbitrary Lagrange-Euler(ALE)method. The results show that the blade-passing frequency is consistent with the frequency of pressure fluctuations, and the impeller rotation is the main reason for the pressure fluctuation. The maximum deformation on the blade appears at the blade tip, and the maximum stress on the blade occurs at the juncture between the blade and the hub. Within the range of 0.6-1.4 times of the rated speed of the impeller, it is difficult to find a reasonable speed that maintains a certain difference between the natural frequency of each order of the rotor and the blade-passing frequency(or its multiple frequency). However, after ignoring the possibility of secondary resonance, there is an optimum speed to achieve a reasonable difference between the natural frequency and the main frequency of each order.

In order to improve the throttling performance of the throttle valve under high sulfur conditions, a sleeve choke valve was taken as the research object, and the 3D Euler-Euler multiphase model combined with the standard k-ε turbulence model was applied to investigate the gas-solid twophase flow within a sleeve choke valve. The velocity field distribution, turbulent viscosity field distribution, flow characteristics and flow resistance characteristics under different valve openings, throttling hole structures and sizes, and inlet particle solid content were analyzed and afterward 〖JP2〗compared with the experimental results. The results show that the flow velocity within the equilateral nozzles decreases with the increase of the valve opening, which can alleviate the erosion wear on the nozzle wall and facilitate the flow of fluid inside the throttle valve. The velocity and pressure within the equilateral triangular nozzles change significantly in comparison with other nozzle structures. The core area of the opposing jet near the nozzle outlet is much longer, resulting in the severe erosion wear area close to the outlet of the throttle valve. In addition, 〖JP2〗the interaction frequency between sand particles increases with the increase of the solid concentration. The intensity of the vortex flow existing near the inlet of nozzles is slightly weakened, which significantly affects the overall flow performance and erosion wear of the throttle valve.

In order to study the effect of flow conditions on the hydraulic performance of bulb pump systems, computational fluid dynamics methods were used to numerically calculate the unsteady flow characteristics inside bulb pumps under uniform and non-uniform flow conditions. The velocity distribution data were extracted from the outlet section of the inlet passage in the pump station as the non-uniform inflow conditions of the model pump, and the uniform inflow was compared. Based on the N-S equation and SST turbulence model, the unsteady flow behavior under multiple working conditions in the bulb tubular pump was simulated. The hydraulic losses and flow fields characteristics of the model pump system under different inflow conditions were analyzed by using the method of entropy generation and pressure fluctuation. The results show that the given non-uniform inflow conditions will cause non-uniformity flow in the impeller and diffuser domains, reducing the hydraulic performance of the pump systems. Based on the comparative analysis of total pressure loss and entropy production loss, it is found that the entropy production analysis method can evaluate the hydraulic performance of flow components. The energy loss mainly cover turbulent entropy production and wall entropy production. The effect of single grid volume on the local power loss area were visualized and quantified with entropy production theory. Through the pressure pulsation characteristics analysis, it is found that the non-uniform inflow conditions does not change the original amplitude frequency characteristics of the cross flow pump systems, but it will increase the fluctuation amplitude, which is not conducive to the stable operation of the pump device systems.

Focusing on the Fengle River Irrigation District in Jiuquan City, Gansu Province, a refined spatiotemporal canal water distribution optimization model based on the WEAP model was developed, which was achieved by selecting a representative hydrological year, conceptualizing the irrigation district′s water distribution infrastructure, accurately identifying the irrigation district′s cropping patterns, and determining crop water requirements for different irrigation control areas. The model′s objective function minimized irrigation water deficits. Considering crop spatial distribution and water requirements during each growth stage, six different canal water distribution priority schemes were selected and compared to analyze the resulting water allocation process and irrigation benefits. The results indicate that, in an extremely dry representative hydrological year, the mismatch between the irrigation district′s traditional water distribution practices and actual crop water needs is significant, leading to yield reductions in areas with lower water distribution priority. Prioritizing water allocation to crops with higher water demand, while ensuring adequate ecological flow in the river, results in a higher degree of coupling between water distribution priority and crop water needs, leading to more rational water allocation. A water distribution scheme prioritizing the irrigation of maize-growing areas within the district achieves both equitable irrigation benefits and higher crop yields and economic returns, exceeding the average yield of other schemes by 6.9% and the average economic benefits by 10.5%. The water deficit rate deviation among canals with the same priority order is only 0.067, which is superior to the 0.163 and 0.164 deviations observed under the irrigation district′s traditional single-year and two-year priority schemes, respectively. The findings provide important technical guidance for improving water resource utilization efficiency and benefits in irrigation districts.

To address the discrepancy between the spatial arrangement of pump unit equipment and the optimization of pump device performance, a novel design approach utilizing a wide-body vertical shaft was proposed. Utilizing the three-dimensional turbulence numerical calculation method in conjunction with entropy production theory, the hydraulic characteristics between a wide-body vertical shaft inlet channel and two conventional conical vertical shaft inlet channels were compared. A prototype of a wide-body vertical shaft inlet water pump was developed and fabricated, and its energy performance, cavitation behavior, and runaway characteristics across five different blade angles were evaluated. The findings indicate that the internal flow field of the wide-body vertical shaft configuration closely resembles that of the other two configurations, exhibiting a flow velocity uniformity of approximately 95% and a weighted average angle exceeding 89° under the design flow conditions. The hydraulic losses remain consistent across different flow conditions, with entropy production in the front section of the vertical shaft constituting merely 7.470% of that observed in the rear section. Moreover, the broad profile of the front section of the vertical shaft does not influence the energy dissipation within the flow channel. At a blade angle of 0°, the water pump device achieves an efficiency of up to 79.19%. The critical cavita-tion margin for the pump device with five different blade angles is below 6.0 m. At a blade angle of -6°, the maximum runaway speed, with a head of 2.36 m, is 278.6 r/min. The hydraulic characteristics of wide-body vertical shafts closely resemble those of traditional vertical shafts, while also posses-sing the capability to concurrently satisfy the demands of equipment configuration and pump device performance.

According to the relevant requirements of the national standard ″Submersible Plug-Flow Mixer″(GB/T 33566—2017), the inspection of submersible mixers must be carried out in an annular inspection water tank. However, the annular inspection tank is expensive and it is difficult to measure the water velocity. As a result, the current research on the flow field characteristics of submersible mixers lacks strong experimental support. Therefore, by taking QJB7.5/12-620/3-480/S submersible mixer as the research object, flow velocity experiments based on an existing annular detection pool of Shaoxing Quality Inspection Institute were conducted, and compared the full flow field comprehensive numerical simulations performed by CFD software. It is concluded from the study that within the stan-dard pool flow field range of the submersible mixer, the flow characteristics of the test and calculation are highly similar. In the effective push flow section of the submersible mixer, the velocity in the central area increases first and then decreases with the increase of the advancing distance, and the flow velocity reaches a maximum value of about 0.600 m/s near the propulsion distance of 5.0 m. Due to uneven flows causing some deviation in axial push flow for the submersible mixer, both sides of the channel exhibit relatively gentle water velocities. However, water velocity on the outer wall side is lower than that on the inner baffle side. In this experiment, when the advancing distance reaches 15.0 m, the velocity at all measuring points is lower than 0.300 m/s. Combined with numerical calculation results, the equi-valent effective push flow length of this model of submersible mixer is 13.64 m, with an equi-valent effective volume of 218.24 m³. It exhibits a specific power consumption rate(SPCR)of 32 units. Furthermore, the average flow velocity within the annular pool is approximately 0.153 m/s. The research fills the gap in the flow experiment of submersible mixers, promotes the implementation and continuous improvement of relevant standards, and has great significance for the performance cognition and future development of submersible mixers.

The deformation of panel rockfill dams is influenced by external loads and internal material creep. The presence of an excessive number of influencing factors can lead to feature redundancy and result in overfitting, thereby compromising prediction accuracy. Conversely, a lack of sufficient factors may lead to incomplete information representation, causing poor predictive performance and limited model generalization ability. Hence, it is crucial to build a comprehensive and interpretable set of factors to optimize them accordingly. To address these challenges, a predictive model for the deformation of panel rockfill dams utilizing an integrated factor optimization algorithm was introduced. ReliefF and Shapley additive explanations(SHAP)algorithms were employed to rank the importance of factors through weighted integration. Subsequently, non-essential factors were eliminated based on an analysis of the threshold of cumulative contribution rate differences, leading to the identification of key factors. By taking a concrete panel rockfill dam in Xinjiang as the research object, the feature shrin-kage rate(FRR), normalized mean absolute percentage error(nMAPE), mean absolute error(MAE), mean square error(MSE), and coefficient of determination R² were used as the evaluation indexes. The experimental results show that the algorithms proposed in the paper can accurately obtain the best factors in the face of different prediction models, which can effectively improve the prediction accuracy. Compared to conventional factor optimization techniques, the proposed approach exhibits greater adaptability and delivers more significant predictive enhancements, effectively addressing issues related to inadequate prediction capability caused by either redundant or insufficient influential factors. Furthermore, it enhances the generalization capacity of the model and offers an efficient method for optimizing factors in research pertaining to dam safety monitoring.

This study systematically investigated the force characteristics of a large two-stage double-suction horizontal condensate pump under different operating conditions by integrating the operational requirements of a specific power plant with a method that encompasses optimized design, three-dimensional flow field simulation, and experimental validation. Firstly, the reliability of the numerical analysis method and the accuracy of the optimization design parameters were verified through comparative assessment of numerical calculations and experimental tests. Secondly, unsteady numerical simulations were conducted to analyze the flow field variations and force characteristics of the two-stage double-suction horizontal condensate pump under normal, transient, and startup operating conditions. The findings indicate that the point of minimum pressure within the flow passage of the first-stage impeller is situated at the rear side of the blade inlet, and the region of low pressure is notably confined. This indicates that the impeller exhibits strong cavitation resistance. The axial and radial forces of the primary and secondary impellers were calculated and analyzed under transient and startup conditions. It is found that the maximum axial and radial forces of the primary impeller are 3 148.546 N and 4 642.354 N, respectively. In comparison, the maximum axial forces and maximum radial force of the secondary impeller are 2 132.887 N and 5 906.412 N, respectively. All recorded force values meet the design requirements, indicating that the condensate pump is capable of maintaining safe and stable operation requirements under various working conditions, thereby achieve the expected design objectives.

Prevailing Bayesian parameter inversion techniques have often been marred by extended computational durations, diminished computational precision, and sub-optimal accuracy. Hence, a hybrid surrogate model underpinned by the multiple attempts of differential evolution adaptive Metropolis(MT-DREAM _(ZS))algorithm was introduced, which offered a more scientifically grounded approach for determining the weight coefficients of individual models, and was modified through Pareto optimization-based dynamic weight coefficient multi-objective optimization. Three distinct machine learning methodologies including multivariate adaptive regression splines, artificial neural network random forest, and random forest were integrated into the Bayesian framework to establish a composite model. Additionally, the posterior distribution of seepage parameters was deduced, while thoroughly accounting for uncertainties present in the inversion procedure. Combined with the monitoring data of the actual project, the gap between this combinatorial agent model and other models was compared and analyzed by calculating the prediction performance index R² and RMSE. Research findings substantiate that the hybrid surrogate model, coupled with the novel technique for weight determination of individual models, boasts superior fitting precision and predictive efficacy. Compared with the traditional method, the improvement rate is 15%-20% on average. By applying the inverted seepage parameters to simulation experiments, a new approach is provided for the development of dam seepage detection research.