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Journal of Drainage and Irrigation Machinery Engin
 
2020 Vol.38 Issue.4
Published 2020-04-25
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2020 Vol. 38 (4): 1- [Abstract] ( 17 ) [HTML 1KB] [ PDF 16715KB] ( 337 )
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2020 Vol. 38 (4): 2- [Abstract] ( 20 ) [HTML 1KB] [ PDF 968KB] ( 408 )
325 Comparison of hydraulic performance between submersible tubular pump device with motor front and rear arrangements
LU Weigang*,WANG Dongwei,SHI Wei,LIU Jun,XU Lei
In order to make the submersible tubular pump device get better and more application in the pumping station with low head, a new type of motor front arrangement for submersible tubular pump device was put forward. Based on the design parameters of a large-scale submersible tubular pumping station, two types of submersible tubular pump systems which are submersible tubular pump devices with motor front and rear arrangement were designed respectively. The three-dimensional flow fields in the two types of submersible tubular pump devices were calculated and analyzed respectively with the method of numerical simulation. The head and efficiency of pump devices were predicted, and the hydraulic performances and structural characteristics of the two types of submersible tubular pump devices were compared. The results show that the water flow contracts gently and evenly with distinct flow lines in the inlet conduits of the two types of submersible tubular pump devices. The water flow diffuses gently without vortex or other bad flow pattern in the outlet conduit of the motor front arrangement scheme. The main flow is inclined to the lower right side and vortex exists on the upper left side of the conduit diffusion section in the outlet conduit of the motor rear arrangement scheme. The conduit head loss of the motor front arrangement scheme is small and the pump device efficiency is high; the hydraulic performance of the motor front arrangement scheme is better than that of the motor rear arrangement scheme. The motor seal of the motor front arrangement scheme is more reliable, the motor supporting structure is more reasonable and the hydraulic design of the guide vane of the pump is more mature. Therefore, the scheme of submersible tubular pump device with motor front arrangement should be given priority to the scheme of motor rear arrangement.
2020 Vol. 38 (4): 325-331 [Abstract] ( 26 ) [HTML 1KB] [ PDF 5017KB] ( 475 )
332 Influence of back blade on wear of heavy slurry pump under low flow condition
PENG Guangjie,*,ZHOU Guoxin,HU Ziqiang,ZHOU Hong
Considering the wear caused by the application of heavy slurry pump operating under conditions deviating from design conditions, the Particle model was used to simulate the transport of high-concentration slurry in the heavy slurry pump and the experimental verification was carried out. The influence of the front and back blades of the impeller on the local wear of the heavy slurry pump with throttle design under the low flow condition was analyzed. The results show that the internal flow field of slurry pump with throttle design is more unstable than that of slurry pump under the low flow condition. The head drops by 3%-10%. The front and back blades have little effect on the particle volume fraction distribution inside the jacket, but have significant effects on particle slip velocity. When a heavy slurry pump with the front and back blades operates under low flow conditions, the slip velocity of solid particles at the interface between jacket and rotor near the tongue will increase sharply. It will cause serious local wear and seriously affect its service life. The removal of the front and back blades can effectively reduce the particle slip velocity at the interface to reduce wear. However, the removal of the front blades will also lead to backflow increase in the front cavity, which will increase the vortex intensity in the front cavity. As a result, the wear of the inner side of the front guard plate is aggravated.
2020 Vol. 38 (4): 332-338 [Abstract] ( 31 ) [HTML 1KB] [ PDF 3111KB] ( 605 )
339 Numerical calculation and experimental verification for axial force on mixed flow pump
DONG Zhiqiang
A volute-type mixed flow pump is taken as an example to construct a leak-free model based on pressure distribution theory. A leakage model based on the true flow of the pump cavity was proposed and constructed. The flow of the two models under the conditions of 0.03Qopt-1.20Qopt was simulated. The curves of the respective axial forces with the flow rate were calculated, and the numerical calculation results, theoretical calculation results and experimental results were compared. Meanwhile, the accuracy of different calculation methods and the influence of leakage flow on axial forces were analyzed in detail. The results show that the back cavity pressure of the impeller cover is the main factor for the generation of axial force, and the leakage flow can effectively reduce its internal pressure; the numerical calculation method based on the leak-free model and the theoretical calculation method are both based on the assumption that there is no leakage in the chamber of the cover, ignoring the influence of leakage flow on axial force, lea-ding to a large deviation between the calculation value and the test value. The maximum errors of the two calculation methods are 25% and 44% respectively; the numerical calculation data of axial force based on the leakage model are close to the test data, and the maximum error is within 10%. The calculation accuracy has been greatly improved, indicating that the numerical calculation method of axial force based on the leakage model has higher accuracy and feasibility.
2020 Vol. 38 (4): 339-345 [Abstract] ( 38 ) [HTML 1KB] [ PDF 2600KB] ( 528 )
346 Influence of splitter blade on pressure pulsation of high-speed well pump
WU Guoqiao,ZHANG Jingchao,JIANG Xiaoping,*,WANG Li,WANG Xinwei
Aiming at the stability problem of high-speed well pump by using splitter blade design, three-dimensional models of key parts such as impeller and guide vane were established by using Creo3.0 software. Based on the good agreement between the CFX numerical simulation data and the hydraulic characteristic experimental data, the ratio of the inlet diameter of the splitter blade d1 to the outer diameter of the impeller D2 was defined as a dimensionless coefficient σ which expressed the comprehensive characteristic parameters of the splitter blade. Three impeller schemes with different lengths of splitter blades were designed and the value σ was selected 0.60, 0.62 and 0.65 respectively. The detailed numerical simulation and analysis of pressure pulsation for the dynamic and static interfe-rence regions of each scheme were carried out. The results show that the amplitude of pressure pulsation is related to the radial distance between the monitoring points and the interface, and the larger the radial distance, the smaller the amplitude of pressure pulsation. The pressure pulsation of each monitoring point decreases with the decrease of the length of splitter blade. When the length of splitter blade is reduced to a critical value, the pressure pulsation is basically unchanged. When σ=0.62, the pressure pulsation amplitude is small, and pulsation cycle is clear. Except for the monitoring point on the middle streamline, the main frequency of pressure pulsation of each monitoring point is greatly influenced by impeller blade frequency. The splitter blade has great influence on the pressure pulsation of monitoring point on the middle streamline.
2020 Vol. 38 (4): 346-352 [Abstract] ( 55 ) [HTML 1KB] [ PDF 3689KB] ( 609 )
353 Comparison and analysis of turbulence models for numerical simulation of cavitation flow in hydrofoil with gap
LU Yuheng,RAN Hongjuan*,SHI Tianjiao,LIU Yong,QIAN Xinru
The CFD method was used to analyze the flow around a hydrofoil with a gap to compare the effects of different turbulence models on the calculation of clearance leakage cavitation and the flow characteristics. Hydrofoils with different angles of attack and clearances were selected and three commonly used turbulence models were chosen to calculate the cavitation caused by clearance leakage vortex. The results show that the density correction method RNG k-ε model is more accurate in predicting the shape of leakage cavitation and the velocity distribution in the main direction near the leakage vortex. Under the influence of wall conditions and airfoil wake, the velocity in the main direction at the location of leakage vortex has a larger value when the gap is 10 mm. For a small clearance, the shear cavitation inside the airfoil clearance is stronger, and the leakage cavitation above the airfoil is farther from the upper surface of the airfoil. When the clearance is increased to 10 mm, the vortex is allowed to develop for a longer distance and collapse more slowly. The fillet of the airfoil tip can guide the clearance flow to a certain extent, which makes the velocity distribution inside and near the clearance more uniform. The fillet can also have an effect on the location where the cavitation occurs.
2020 Vol. 38 (4): 353-359 [Abstract] ( 41 ) [HTML 1KB] [ PDF 2766KB] ( 612 )
360 Influence of mass imbalance on radial force of single-blade impeller
ZHANG Hua,CHEN Bin*,WANG Yuan,XU Yunfeng,WANG Zhen
To find a way to improve the radial force of single-blade centrifugal impeller, a single-blade impeller with single-end counterweight was studied. The unsteady numerical calculation was carried out on the premise of verifying the accuracy of the steady-state numerical calculation by hydraulic characteristic test. The radial force vector distribution of the single-blade impeller was obtained; and it was found that the direction of the radial force was fixed with the relative position of the blade near the design condition. Based on the vector average of radial force in the whole period, the magnitude and direction of the average radial force were obtained. By using virtual prototype simulation technology, the impeller with balanced mass and eccentric mass were obtained; the centrifugal force generated by the eccentric mass of the impeller under the action of rotation was just closed to the average hydraulic radial force and the direction was opposite. Through the unidirectional fluid-solid coupling simulation, it was found that the radial force of impeller with eccentric mass greatly decreased in the actual operation, which proved that the method of reducing and adjusting the radial force of single-blade impeller through mass eccentricity was feasible.
2020 Vol. 38 (4): 360-364 [Abstract] ( 55 ) [HTML 1KB] [ PDF 1974KB] ( 651 )
365 Influence of different parameters on numerical simulation of vertical-axis marine current turbine based on OpenFOAM
JI Renwei,SHENG Qihu,*,SUN Ke,LI Yan,ZHANG Yuquan,ZHANG Liang,
Using the PimpleDyMFoam solver in open-source computing software OpenFOAM, based on the SST k-ω turbulence model and PIMPLE algorithm, a numerical simulation method of vertical-axis marine current turbines(VMCTs)is proposed, and the calculated results are compared with the experimental results. The results show that the numerical simulation method is feasible. Compared with other commercial softwares, this method has the advantages of higher solution efficiency and greater flexibility. According to the needs of users, the solver can be built on the basis of original code, and the corresponding discrete method can be optimized. This method can achieve optimization algorithms, save time and cost, etc. Secondly, the effects of different parameters(mesh density, time step, the selection of sidewall boundary conditions and inlet turbulence intensity)on numerical simulation of the VMCT are studied in detail. The findings summarize an effective CFD simulation strategy based on OpenFOAM and provide a valuable reference for future CFD simulations of VMCTs.
2020 Vol. 38 (4): 365-371 [Abstract] ( 42 ) [HTML 1KB] [ PDF 2153KB] ( 451 )
372 Analysis of effect of blades angle on hydraulic performance for pumping system of water diversion pumping station
SHI Wei,*,CHENG Li
In order to investigate the effect of blades angle on the hydraulic performance for the pumping system of water diversion pumping station, the pumping system with the whole flow passage was simulated by computational fluid dynamics technology. The effect of changing blade angles on flow pattern and hydraulic performance of inlet passage, outlet passage and impeller was analyzed based on the simulation result. The result indicates that the recirculation is found at the area near hub while the blade angle deviates design values. The flow pattern of flow passage becomes bad and hydraulic loss of flow passage increases while the deviation angle increases.When the blade angle is adjusted to -8°, the relative value of hydraulic loss of the inlet and outlet passages is the largest, which is 1.28 and 2.89 respectively(compared with the blade angle -0° condition). At the same deviation angle, the relative value of hydraulic loss of outlet passage is larger than that of inlet passage. The simulation result of design condition was compared with the test result, which shows that the relative uncertain value of head is 1.2% and the relative uncertain value of effectiveness is 2.1%. It means that the simulation result has good agreement with the test result. The research results can could provide reference for the operation management of water diversion pumping station.
2020 Vol. 38 (4): 372-377 [Abstract] ( 38 ) [HTML 1KB] [ PDF 2415KB] ( 561 )
378 Analysis of outlet flow state of firefighting monitor rotary main structure
XUE Lin,YUAN Shouqi,XIANG Qingjiang*,XU Jie
The main structure of firefighting monitor has rotary forms that cause the water swirl in the pipe and has great influence on thefirefighting monitor performance. The rotary structure is the combinations of straight pipes and different angle elbows. Numerical simulations were done with standard k-ε turbulence model for inner flow of three kinds of rotary structure, which diameter was 180 mm. Three rotary structures were named traditional rotary, half rotary and large rotary respectively. The outlet flow state and hydraulic losses were compared and analyzed. The outlet parameters include the average turbulence kinetic energy, velocity distribution curves and Dean vortex. The results show that the hydraulic loss of three types rotary structure are reduced with the curvature R/d increasing. As the R/d is 1.4, the traditional rotary has the smallest hydraulic loss and the half rotary is the largest. The outlet velocity curves show that the largest velocity occurs near the wall not near the center of pipes, this means that the flow has swirl characteristic at the outlet. When the R/d is 1.4, the large rotary structure has smallest average turbulence kinetic energy at the outlet, and streamline has one clockwise basic vortex which is consistent with traditional rotary structure, but the vortex intensity which is obtained after integral the outlet vorticity is smaller. The format of large rotary structure is better for subsequent flow in tube and nozzle of firefighting monitor.
2020 Vol. 38 (4): 378-383 [Abstract] ( 34 ) [HTML 1KB] [ PDF 3180KB] ( 630 )
384 Three-dimensional simulations on dynamic characteristics of flow impacting entrapped air pocket in undulating pipeline
LU Kunming,ZHOU Ling*,CAO Bo,LIU Deyou,WANG Huan
Transient flows in a filling undulating pipeline with entrapped air pocket are complicated, and may cause abnormal pressure surge. Three-dimensional CFD method was introduced to simulate the water-air interaction, and to investigate the three-dimensional(3D)dynamic characteristics of the compression-expansion-deformation entrapped air pocket. On the basis of including the compressibility of air phase, the 3D method considered the elasticity of water phase. Three kinds of turbulence models(Standard k-ε, RNG k-ε, and Realizable k-ε)were used in the simulations, and the comparisons of the results calculated by the proposed 3D CFD model and existing one-dimensional(1D)model, and the experimental results were conducted here. Results show that compared with 1D model, 3D CFD mo-del can better simulates the transient pressures and air-water profiles in the filling undulating pipeline. Moreover, standard k-ε turbulence model more accurately simulates the pressure peaks and fluctuation periods, than RNG k-ε and Realizable k-ε turbulence models. During the filling process, the water-gas two-phases are mixed with each other, and the water-air interface changes freely, which is not perpendicular to the center line of the pipeline, and has a certain angle with the center line of the pipeline; the three-dimensional CFD calculation results can well simulate the dynamic characteristics of short length air pockets.
2020 Vol. 38 (4): 384-389 [Abstract] ( 32 ) [HTML 1KB] [ PDF 3133KB] ( 501 )
390 Characteristics of wind turbine flow field after blade vibration
FANG Yucai,*,GAO Zhiying,YAN Mengmeng,CHEN Yongyan,
In order to study the changes in the characteristics of the flow field of the wind turbine wake after the blades of a horizontal axis wind turbine are shaken, a NACA airfoil wind turbine is used as the research object, and the blade mode is successfully controlled by using a custom UDF code and using dynamic mesh technology, So that the wind wheel performs a waving motion perpendicular to the rotation surface while rotating in three dimensions. In the numerical simulation, In the numerical simulation, the Fluent calculation platform is used to study the velocity field, vorticity field and pressure pulsation characteristics of the wind turbine wake.The research results show that after a vibration is applied, the wind wheel will generate a relative speed gain region near the middle of the leaf and a speed loss region at the tip of the leaf, which will make the blade force more uneven and a larger pressure difference. Accelerate the damage and fracture of the blades; the intensity of vorticity at the blade tip increases after the application of waving vibration, and the shedding of the blade tip vortex is delayed; secondly, the pressure pulsations show periodic fluctuations before and after the vibration is applied, and the radial 0.5 m.The pressure fluctuation is most obvious. By introducing new unsteady factors, this paper reveals the influence of waving vibration on the characteristics of the wind turbine wake flow field, which makes the numerical simulation results closer to the actual operating state of the wind turbine, and provides guidance for wind turbine blade design.
2020 Vol. 38 (4): 390-395 [Abstract] ( 46 ) [HTML 1KB] [ PDF 3534KB] ( 565 )
396 Simulation of deficit irrigation with saline water for spring maize based on SWAP model
YUAN Chengfu,FENG Shaoyuan,*,HUO Zailin,WANG Qingming
In order to explore the appropriate deficit irrigation with saline water management mode for spring maize growth in the Shiyang River Basin of Gansu province, the SWAP model was used to simulate soil water and salinity balance, relative spring maize yield and relative water use efficiency under different irrigation modes, and also the long-term effects of soil water-salt dynamics were also predicted. The simulated results indicate that the optimal irrigation management mode of spring maize is to irrigate four times with total amount of 408 mm for irrigation water with 0.71 g/L and 3.00 g/L during the growing season of spring maize. The two irrigation modes can achieve the aim of saving irrigation water, improving crop yield and water use efficiency, and reducing the soil salt accumulation. The long-term simulation of soil water-salt dynamics indicates that the soil water content and soil salt content can remain relatively stable for the simulation period of time in the optimal irrigation mode of spring maize under winter irrigation. The soil water content increases with the increase of soil depth at the same soil layer in different years. The soil salt content mainly accumulates at the 40-80 cm soil layer under fresh water irrigation of 0.71 g/L and accumulates at the 10-40 cm soil layer under brackish water irrigation of 3.00 g/L. Five-year simulation shows that the irrigation water with 0.71 g/L and 3.00 g/L will not result in soil secondary salinization.
2020 Vol. 38 (4): 396-402 [Abstract] ( 38 ) [HTML 1KB] [ PDF 2147KB] ( 457 )
403 Comparison of saturated hydraulic conductivity of different land use types in Taian brown loam
ZHANG Peng,HU Xinyu,CHEN Guanyun,ZENG Jian,YIN Kai,QIAN Jianjun,ZHANG Qian*
In order to analyze the influence of land use types on soil saturated hydraulic conductivity, the saturated hydraulic conductivity of Taian brown loam in grassland, wheat field and bare land of fruit trees was studied by single-ring infiltration and generalized solution method. The results show that the saturated hydraulic conductivity, infiltration rate and cumulative infiltration, which are measured separately in bare land of fruit trees, grassland and wheat field, decreased in turn. With the increase of time, the cumulative infiltration amount increases continuously. Within 120 min of test time, the cumulative infiltration amount of grassland is the largest, with a value of 78.564 cm.Wheat field infiltration comes second, with a value of 67.609 cm. The bare land infiltration between the fruit trees is the minimum, with a value of 30.082 cm. Using the measured cumulative infiltration and observation time of three land use types of the fitting relation expression of cumulative infiltration rate to estimate the cumulative infiltration, grass and wheat field, bare land of fruit trees cumulative infiltration calculated values and measured values relative errors in 6, 8, 7 minutes fluctuate within 5%, and in 15, 52, 56 minutes fluctuate within 1%, at the same time, the derived soil saturated hydraulic conductivity, Ks of the grassland, wheat field and bare land of fruit trees under the three different land use types is 0.073 1, 0.032 9, 0.015 8, respectively, so as to provide reference for the study on the influence of different land use types on the saturated hydraulic conductivity of undisturbed soil.
2020 Vol. 38 (4): 403-408 [Abstract] ( 54 ) [HTML 1KB] [ PDF 1435KB] ( 772 )
409 Cognition of modernization degree of irrigation district and its influencing factors analysis
ZENG Zhongyi,SHAO Guangcheng*,DING Mingming,YAO Junqi
To determine the content and key points of irrigation modernization,taking the sample data of 35 irrigation districts in Jiangsu Province as examples, the cognition of modernization degree of irrigation district and its influencing factors were studied by structural equation model. The data analysis shows that the standard factor loading coefficient is about 0.75, the Kaiser-Meyer-Olkin value is 0.973 and the Bartlett′s spherical test statistic is 1 682, indicating that the sample data are highly effective and relevant. The results indicate that irrigation and drainage system, water resources measurement and informatization, management system, service assurance, ecological environment, living environment, disaster prevention and mitigation, water resources security, economic efficiency and water efficiency all affect the cognitive degree of irrigation district modernization in various degrees. Among them, irrigation and drainage system has the greatest impact on the cognitive degree of irrigation district modernization, while service guarantee has the least impact on it. The modernization of irrigation district should be comprehensive and integral. It is necessary to make an overall plan for the comprehensive development of irrigation district infrastructure system, management and service system, ecological health system, security system, and efficiency and benefit system.
2020 Vol. 38 (4): 409-414 [Abstract] ( 43 ) [HTML 1KB] [ PDF 1302KB] ( 486 )
415 Analysis of infiltration characteristics of muddy water film hole irrigation under multiple factors
JIANG Ruirui,FEI Liangjun*,FU Yuliang,KANG Shouxuan,LIU Teng
In order to study the single point source infiltration characteristics of muddy water film hole irrigation under multiple factors, the sensitivity of each factor was analyzed. This multifactor study mainly selected four factors such as soil bulk density, soil initial moisture content, membrane pore dia-meter and sediment concentration of muddy water as the influencing factors for indoor experiments. The orthogonal design was applied and the multiple regression analysis method of SPSS software was applied to regression analysis on the cumulative infiltration amount of the unit membrane pore area under the influence of four factors, and the fitting decision coefficient R=0.98 was fitted, which showed that all the influence factors affected the infiltration of the single point source of the muddy water film hole irrigation. The relative value method was used to analyze the influence degree of the infiltration parameters of each factor on the cumulative infiltration of the unit membrane pore, and the significant degree from large to small was the diameter of the membrane hole, the soil bulk density, the soil initial water content and the sediment concentration of the muddy water. The infiltration rate of irrigation point source was weaker.
2020 Vol. 38 (4): 415-420 [Abstract] ( 47 ) [HTML 1KB] [ PDF 1910KB] ( 593 )
421 Speed robust control of permanent magnet synchronous motor in non-ideal network environment
WANG Shichuan,ZHU Xiaoyuan*,LI Doudou,ZHANG Guichen
Aiming at the problem of speed robust control of permanent magnet synchronous motors under the condition of communication time delay in networked control, firstly a time delay dynamic model of permanent magnet synchronous motors was established in a network environment, and then a system speed-control robust controller design was developed based on the model. The Lyapunov-Krasovskii function was used to obtain the stability condition of the system speed control, and the corresponding robust controller gain was further calculated using the LMI toolbox. Finally, in order to verify the controller performance, a controller area network(CAN)communication module was built based on SimEvents, interference signals were introduced to truly reflect the uncertainty delay induced by network communication, and a CAN bus-based speed control system model of permanent magnet synchronous motor was established through MATLAB / Simulink. The motor speed control system model monitored the motor speed, phase current and torque, and conducted simulation and comparative analysis. The results show that in a non-ideal network environment, using the designed speed-regulating robust controller, the system stability is significantly improved compared with the traditional PI controller vector control method, which is sufficient to meet the stability requirements of the permanent magnet synchronous motor speed control.
2020 Vol. 38 (4): 421-426 [Abstract] ( 36 ) [HTML 1KB] [ PDF 6779KB] ( 658 )
427 Experimental study on head loss of a new type of rotatable plate screen filter
SHI Kai,LIU Zhenji*,LI Man
2020 Vol. 38 (4): 427-432 [Abstract] ( 41 ) [HTML 1KB] [ PDF 2256KB] ( 477 )
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