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Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Preferential flow during on-farm irrigation management can reduce water and fertilizer use efficiency and exacerbate the risk of groundwater contamination. Based on potassium iodide-starch dye tracing experiment, this paper analyzes the soil water distribution characteristics under surface irrigation DM, micro-sprinkler irrigation WP1 (20 mm/h), irrigation WP2 (40 mm/h) treatments, verifies the validity of dual-permeability model based on principle of water volume balance, and uses four levels of antecedent water content ( 0.20, 0.25, 0.30, 0.35 cm3/cm3) with five levels of irrigation intensity (12.0, 24.0, 36.0, 48.0, 60.0 mm/h) in a rotating combination design for application analysis. The results show that water infiltrated in the form of uniform matrix flow in WP1 and WP2 treatments as a whole; the soil profile staining area under DM treatment can be clearly divided into substrate flow area (0~6.9 cm) and preferential flow area (>6.9 cm) in the vertical direction. In addition, the matrix flow depth and irrigation uniformity under DM treatment are significantly (P<0.05) smaller than those under WP1 and WP2 treatments, while their the fraction of preferential flow and wetting front curvature are highly significantly larger (P< 0.01) than those under WP1 and WP2 treatments, which indicates that surface irrigation can activate more preferential flow paths, increase the degree of preferential flow development and spatial heterogeneity, and reduce irrigation quality. The dual-permeability model based on principle of water volume balance can effectively predict the trends of matrix flow depth and soil profile staining area ratio under different irrigation intensities (R2=0.927 6, NSE=0.884 4, RSR=0.023 0), and the simulation results of the rotational combination design of antecedent volumetric water content and irrigation intensity show that increasing irrigation intensity or decreasing antecedent water content will increase the degree of preferential flow and reduce irrigation quality. Therefore, this paper recommend using "high-frequency, low-flow" irrigation mode in irrigation management to reduce the reduction of water and fertilizer use efficiency due to priority flow. The research results can provide a theoretical basis for irrigation decision, and the experimental data can provide important data support for the optimization and validation of the preferential flow model. [ABSTRACT FROM AUTHOR]

Under the background of global warming, extreme flood disasters occur frequently, with a particularly significant impact on Xinjiang, which is located in arid and semi-arid regions. The risk of flood disasters in this region is significantly increased. In order to improve the flood disaster response capacity of Xinjiang Province, reduce losses caused by flood disasters, and provide an example for rivers in arid areas to respond to flood disasters, this paper selects Kushan River in Xinjiang to carry out flood process simulation research. Kushan River is located at the western edge of Tarim Basin in southern Xinjiang, which is a typical river in arid inland areas. This paper constructs a flood analysis and calculation model for the Kushan River, determines the key parameters and boundary conditions of the model. A typical flood is selected to validate the constructed model, and four indicators, absolute error (AE), relative error (RE), determination coefficient (R2), and Nash coefficient (NSE), are selected for model evaluation. The calculation results show that the average absolute error of water depth is 24.1 cm, the relative error is 24%, and the determination coefficient is 0.66. The Nash coefficient of flow is 0.86, and the determination coefficient reaches 0.97, indicating that the constructed model and parameter settings have high accuracy. Using high-precision river terrain, flood disaster risk survey results, remote sensing information, a basin data base is established to calculate the flood progression, inundation range, water depth distribution, and inundation duration of the Kushan River under five typical frequencies of 10 year, 20 year, 50 year, 100 year, and 200 year, achieving large-scale simulation of flood routing in arid areas of the entire basin. The research results can provide a technical basis for flood risk analysis of rivers in arid inland areas. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As the lined channels in Northwest China are subject to frost heave soil extrusion damage in winter, coupled with the easy sinking of wet-submerged loess in water, the frost damage of lined channels with wet-submerged loess as foundation is complicated. To address this problem, this paper takes the East First Trunk Canal before and after the renovation of Ningxia Guhai Irrigation District as a prototype, and establishes a simplified three-phase coupled mathematical model of the channel by analyzing the deterioration law of the channel before and after the renovation by frost damage and the plastic damage structure of concrete material. Considering the mechanical properties of wet-submerged loess and the contact behavior between canal base soil and liner plate, the numerical model of thermal-force coupling of lined channels before and after renovation is constructed by ABAQUS software based on the measured data, and the specific situation and deformation law of frost swelling are simulated and analyzed in comparison. By comparing the three physical fields simulated by the two coupled models, the results show that the frost damage of the modified rigid-flexible lined channels has been substantially improved and the stress concentration has been avoided to a certain extent: comparing the field data before modification with the research results, the accuracy and feasibility of the numerical coupled model are verified, and the three physical fields of heat-force-displacement simulated can better reflect the frost swelling mechanism of the actual lined channels, which serves as a reference for the management and modification design of the frost damage of the irrigation channels. [ABSTRACT FROM AUTHOR]

In order to solve the problem of sediment accumulation in the diversion canal, which adversely affects the water supply system, this paper designs a diversion and sand discharge system at the head of the canal to improve the efficiency of water use. According to the measured data of a section of the Yellow River Ningxia, a two-dimensional numerical simulation is used to construct a two-dimensional hydrodynamic model and a sediment model based on MIKE 21 for a section of the Yellow River Ningxia to simulate the water diversion at the head of the canal under two different working conditions. The results of the study show that the diversion channel changes the equilibrium of the hydrodynamic elements of the river, direct diversion canal (case 1) flow dynamics axis has oscillated 46.6m towards the concave bank, the average sand content of the channel is 0.6 kg/m³ and the maximum sand content is 0.89 kg/m³; the axis of flow dynamics in the sand reduction diversion channel (case 2) has oscillated 62.6 m towards the concave bank, the flow velocity at the head of the channel is in the range of 0.2~0.4 m/s, the average sand content of the channel is 0.2 kg/m³ and the maximum sand content is 0.6 kg/m³. Therefore, the design of the head of case 2 can improve the sediment deposition problem of the diversion canal and enhance the durability of the water intake system. [ABSTRACT FROM AUTHOR]

The Tesla valve has a special structural form that can guide the flow entering from the reverse port into two sets of straight/curved channels, and dissipate energy through friction and collision at the end of the guide column, greatly weakening the flow velocity in the pool. This unique flow characteristic is very suitable for designing fishways. However, direct applying the original structure of Tesla valves as a fishway has been proven to have significant limitations. The original structure of the Tesla valve fishway is optimized in this paper. By adjusting the aspect ratio of the straight/curved channel in the fishway pool, hollowing out the guide column, and increasing the length of the opening end, a new Tesla valve fishway with relatively independent energy dissipation channels and fish upstream channels has been obtained. The hydraulic characteristics parameters of the optimized Tesla valve fishway are compared with the original structure using numerical simulation, with a focus on analyzing the flow velocity variation, flow field, and turbulent energy distribution of the new Tesla valve fishway. The results show that the new Tesla valve fishway has significant advantages compared to the original structure. While maintaining the same energy dissipation efficiency, it effectively improves the flow pattern in the pool, and the overall flow velocity and turbulent kinetic energy are smaller than the original structure. The new structure significantly increases the proportion of rest areas. When the pool bottom slope gradient from 1% to 3%, the proportion of rest areas in the original Tesla valve fishway is 8.5% to 1.2%, while the proportion of rest areas in the new Tesla valve fishway is 44.7% to 25.8%, increasing the possibility of successful fish upstream migration. The flow velocity and turbulent kinetic energy of the new structure increase with the increase of the bottom slope gradient, but the flow velocity remains low in the fish upstream channels, while the high flow velocity mainly occurs in the energy dissipation passage. The maximum flow rate increase rate in the energy dissipation channel of the first two stages of the pool is relatively high, while after the third stage of the pool, the increase rate tends to slow down. The overall turbulent kinetic energy in the fish upstream channels is relatively low. When the bottom slope gradient is less than 2.5%, the upstream conditions and economy of the fishway are better. [ABSTRACT FROM AUTHOR]

In order to explore the water movement characteristics of ball valve and DN63 tee combined deformation variant, this paper uses Fluent software to numerically calculate the combined deformation variant based on the Realizable k-ε turbulence model, and analyzes the effect of valve opening, Reynolds number and splitting ratio on the comprehensive resistance coefficient of combined deformation variant. The results show that when the flow velocity and splitting ratio are certain, the opening degree of the ball valve has a significant effect on the comprehensive loss of the combined deformation parts, with the increase in the opening degree, the flow velocity gradient in the spool decreases, and the vortex area is formed before and after the valve decreases. After the Reynolds number is more than 1.8 x 105, it tends to be stable. The most important factor causing the integrated local loss of the combined deformation is the size of the valve opening, followed by the variation of the shunt ratio and Reynolds number. [ABSTRACT FROM AUTHOR]

During the large-flow water transmission of the middle line of the South-to-North Water Diversion Project, some aqueducts experienced varying degrees of water level fluctuations, which had a certain impact on safety scheduling, especially the shorter the aqueduct body, the more obvious the phenomenon. In this paper, the RNG k-ε model and Tru-VOF method are used to establish several sets of full three-dimensional numerical models with different tank lengths for typical aqueducts, and explore the influence of tank length parameters on water level fluctuations. The results show that the Carmen vortex street formed at the exit of the tail pier downstream of the aqueduct is the source of fluctuations, and the vortex causes local water blockage, which in turn generates fluctuations to be transmitted upstream. With the increase in the length of the tank, the fluctuation transfer energy is gradually dissipated, the maximum flow velocity and the amplitude of water level fluctuation continue to decrease, and when the length exceeds 800 m, the water level fluctuation energy is basically dissipated. The results can provide a reference for the smooth scheduling and safe operation of the project. [ABSTRACT FROM AUTHOR]

The large-scale vortex formed in the Savonius hydro turbine wake field tends to act on the back of the blade, increasing the negative torque of the rotor, resulting in a decrease in its power coefficient. In this paper, three rectifier grids of different structures are arranged at 0.8D (D is the diameter of the wheel), 1.2D and 1.6D from the rotation center of the S wheel, and the influence of the rectifier grid on the power characteristics and inflow field of the wheel is studied by using CFX for numerical simulation calculation and analysis. The results show that when the leaf tip speed ratio r is 0.91, the torque coefficient and power coefficient of the four blade rectifier grids are set at 1.2D from the rotation center of the S wheel. The values 0.273 and 0.192 for the largest torque and power coefficient, which are 2.5% and 2.3% more than the torque coefficient and power coefficient without rectifier grid, respectively, it is also found that after the fairing grid is set behind the rotor, the vortex scale in the wake field is significantly reduced compared with that without the rectifier grid. The fluid velocity distribution after the rotor becomes uniform, which reduces the flow loss caused by the secondary flow on the one hand, and effectively reduces the pressure pulsation in the wake field on the other hand. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The sediment-carrying capacity is reduced due to the rise of water level and the reduction of velocity, which leads to sedimentation in the reservoir, especially in front of the dam. Therefore, the storage capacity, flood control ability, and power generation are reduced, which affects reservoir functions and economic efficiency owing to reservoir sedimentation. The main measures to solve the problem of reservoir sedimentation include dredging in reservoir, reducing inflow sediment realized by soil protection and vegetation, as well as reservoir operation management such as "storing clear water and discharging muddy flow", and sediment discharging by heterogeneous flow, etc. In this paper, a normal funnel device with the smooth surface that has arbitrary order derivative is designed for discharging sediment in reservoir. The Euler two-phase flow near the normal funnel is numerically simulated with the Realizable k-e turbulence model on rectangle and O-type grids. Numerical model is tested by data on experiment flow that carried out in flume. The flow velocities, vorticities and sediment phase concentrations are analyzed under different boundary conditions. Research shows that velocity gradient is large in normal funnel, and phase concentration contours display the V-shaped asymmetrical distribution. Three large vorticity areas appear in the front edge, the left and right rear sides of the normal funnel. The large flow velocities and small resistance appear near the wall of the normal funnel. The average sediment concentrations at the output of the normal funnel are 0.462, 0.521 and 0.558 under three boundary conditions. The average vorticity is reduced by 25.8%-27.2%, the efficiency of discharging sediment remarkably increases with 15.2%-16.5% in contrast to the cone funnel. It demonstrates that the normal funnel is more favorable than the cone to smoothing flow, reducing energy dissipation, enhancing the capacity of sediment transport and discharging sediment outwards reservoir. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to study the effects of water level drop and rainfall on the coastal wading slope in the Three Gorges Reservoir area, this paper takes the Chicken Brain Shell Landslide as an example, and uses the numerical simulation method to analyze the deformation and failure of the Chicken Brain Shell Landslide under the conditions of reservoir water level fall, rainfall and coupling between the two. Firstly, the stability of landslides under different working conditions is calculated by Morgenstern-Prince method in the two-dimensional model, and the three-dimensional landslide model is used to monitor the changes of pore water pressure, stress and displacement of the landslide, so as to analyze the failure mechanism of the waterslide landslide. On this basis, the influence of single indicators of reservoir water level decline rate and rainfall intensity on the stability of landslide is analyzed. The results show that in the two-dimensional calculation, the reservoir water level slowly drops from 175 m to 145 m, and the landslide is the most dangerous when the chicken brain shell is the most dangerous in the event of heavy rainfall in 50 years, and the stability coefficient of the landslide is 1.032, and the landslide is in an unstable state. In the 3D model, the permeability and displacement of the slope body change greatly, in which the reservoir water level slowly decreases from 175 m to 145 m and encountered heavy rainfall in 50 years, the landslide had the maximum displacement, of which the horizontal displacement reached 31.38mm and the vertical displacement is 31.13 mm. The numerical prediction model shows that the displacement of the landslide mainly occurs in the middle and rear part, so when the reservoir water level drops and is accompanied by heavy rainfall, the deformation of the trailing edge of the landslide should be observed. The analysis of single factor shows that when the landslide only adjusts the reservoir water level decline rate, the stability of the landslide decreases as the reservoir water level decline rate increases, and when the water level drop rate is 4.2 m/d, the landslide becomes unstable. The influence of rainfall factors indicates that the greater the rainfall intensity and the longer the rainfall duration, the more likely the landslide becomes unstable, and the landslide stability coefficient reaches 0.968 for 4 days once in 50 years, entering an unstable state, so it is necessary to monitor and warn the landslide during the period of rapid decline of reservoir water level and continuous heavy rainfall. [ABSTRACT FROM AUTHOR]

The equipment supercooling problems have been observed in the operating condition of the air supply system in some pumped storage power stations. It is a critical safety risk for the air supply system when it is working with the compressed air. Especially for the different valves in the pipelines, which feature short-length and complex internal structure, usually cause air velocity increasing rapidly and temperature decreasing sharply, challenging the system sealing performance and connection strength. Since the numerical simulation researches about air supply system are still rarely reported, it puts forward the urgent need of some related researches. In this paper, the SA turbulence model is adopted for the transient full-channel numerical simulation research on the air supply system of pumped storage power stations. Present work puts emphasis on the extreme temperature decreasing phenomenon of the valves, occurring when the air supply system releases highly compressed air to drain the water out of the runner chamber. And some critical aspects of the above valve temperature-drop problem, including the occurrence location, drop level and mechanism are focused on and analyzed. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to study the influence of the linear shaped pier on the inflow into the curved forked river, this paper uses the Tongcheng Sluice as the research model. Firstly, the most complex flow pattern is selected from different working conditions, and then based on the worst flow pattern, a linear shaped pier is set at different positions in front of the gate and the bend. The flow field parameters are respectively measured in Tongcheng Sluice's curved model, and the angle index between the inlet velocity vector and the direction of the gate pier is established to analyze the state of the curved forked river. At the same time, the FLUENT software is used for numerical simulation verification. Tecplot software is used for post-processing analysis. Finally, the optimal rectification scheme is selected based on the physical model. The results show that the angle deflection coefficient between the gate inlet velocity vector and the gate pier direction can directly evaluate the pros and cons of the inlet flow state. A linear shaped pier is placed in front of the gate. As the linear shaped pier is closer to the gate, the flow pattern in front of the gate will be more chaotic. In addition, the vortex in the bend can be significantly improved by setting a linear shaped pier in the bend, and the linear shaped pier is arranged 20 m from the convex bank on the center line of the bend, and the flow state in front of the bend and gate are significantly improved. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)