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Journal of Drainage and Irrigation Machinery Engin
2024 Vol.42 Issue.4
Published 2024-04-25

2024 Vol. 42 (4): 1- [Abstract] ( 4 ) [HTML 1KB] [ PDF 20151KB] ( 88 )
2024 Vol. 42 (4): 2- [Abstract] ( 4 ) [HTML 1KB] [ PDF 1339KB] ( 94 )
325 Optimization design of meridional surface of a centrifugal pump impeller based on high-dimensional hybrid model
ZHANG Jinfeng,YU Xinhou*,GAO Shuyu,CAO Puyu,ZHANG Wenjia
In order to improve the operation efficiency and head of centrifugal pumps under the design conditions, a centrifugal pump impeller optimization design method based on high-dimensional hybrid model was proposed. A single-stage centrifugal pump with specific speed of 157 was selected as the research object for this study. The optimization variables were parameterized in CFturbo software, and then combined with numerical simulation to obtain the training set of the high-dimensional hybrid model. By using MATLAB machine learning on the obtained training set, a high-dimensional support vector regression model between efficiency, head and optimization parameters was obtained, and a genetic algorithm was used for the optimization. Under the design working conditions, the predicted efficiency and head values of the fitted high-dimensional hybrid model are 1.5% and 3.2 m higher than the original model, respectively. The efficiency and head values of the optimized scheme verified by numerical simulation are 0.9% and 2.1 m higher than the original model, respectively. This case study shows that the application of a high-dimensional hybrid model in the optimal design of a centrifugal pump impeller can achieve rapid optimization and improve the hydraulic performance of the centrifugal pump.
2024 Vol. 42 (4): 325-332 [Abstract] ( 8 ) [HTML 1KB] [ PDF 2752KB] ( 134 )
333 Influence of geometric parameters of front wear-ring of a vertical self-priming pump on its self-priming performance
ZHAO Weiguo,*,QIANG Huanhuan,XU Qiang,LIU Mingjian
In order to explore the influence of the geometric parameters of the front wear-ring of a vertical self-priming pump on its self-priming performance, this study takes the 350WFB-1200-50 externally mixed sealless vertical self-priming pump as the research object. With other parameters unchanged, a total of 20 solutions were designed by changing the numerical values of the anterior orifice ring gap δ and the anterior orifical ring length l. Using a research method that combines numerical calculation and experimental verification, the external characteristic curve of each design scheme and the pressure difference between the inlet and outlet of the front wear-ring are obtained through steady numerical calculation, and the gas volume distribution cloud map of the middle section at different times of each design scheme was obtained through unsteady numerical calculations. The change diagram of the gas content rate at the outlet of the self-priming pump of each design scheme and the self-priming completion time curve of each design scheme were used to study the influence of the geometric parameters of the front wear-ring on its self-priming performance. The study found that the front wear-ring clearance δ and the front wear-ring length l have an effect on the self-priming performance of the self-priming pump, appropriately reducing the front wear-ring clearance δ and increasing the front wear-ring length l can improve the self-priming performance of the self-priming pump, and when the front wear-ring clearance δ is too large, the effect of the front wear-ring clearance δ on the self-priming performance of the self-priming pump is larger than the effect of the front wear-ring length l on the self-priming performance of the self-priming pump.
2024 Vol. 42 (4): 333-341 [Abstract] ( 8 ) [HTML 1KB] [ PDF 13189KB] ( 107 )
342 Self-priming performance of liquid-ring aviation fuel centrifugal pump
ZHANG Ling,YANG Xing,LI Yiming,WANG Kai*,GONG Yongxiang,LIU Houlin
The unsteady gas-liquid two-phase flow in the self-priming process of a liquid-ring aviation fuel pump was simulated using the Mixture model, and change of gas-liquid two-phase distribution in the fuel pump during the self-priming process was analyzed. The changes in gas content, gas-liquid two-phase distribution, pressure and velocity streamlines, entropy production rate, and turbulent kinetic energy in the fuel pump at different times during self-priming were studied. The results show that the suction and exhaust of the fuel pump primarily occur during the early and middle stages of the self-priming process. As the self-priming time increases, the gas content of each monitoring surface gradually decreases. When the self-priming time is 3 s, the gas content at the outlet of the volute approaches 0, and the self-priming process ends. The pressure inside the pump increases as the relative distance increases, and the pressure in the same relative distance plane in the pump increases with the increase of self-priming time. The high-velocity area is mainly concentrated near the partition middle flow path of the impeller and the volute wall, while the low-velocity area is concentrated in tongue of the volute and outlet of the guide-vane during gas-liquid mixing. With the development of the self-priming process, the turbulent kinetic energy and entropy yield inside the pump also increase, and the energy loss inside the pump as well increases by mainly occurring in the impeller blades, guide-vane blades, and outlet of the volute.
2024 Vol. 42 (4): 342-349 [Abstract] ( 9 ) [HTML 1KB] [ PDF 24563KB] ( 107 )
350 Influence of blade angles on performance of micro axial flow hydraulic turbine
YANG Sunsheng*,ZHAO Erce,KONG Xiangxu
In order to investigate the influence of blade setting angle on the hydraulic performance of micro axial flow hydraulic turbine, a micro axial flow hydraulic turbine with a specific speed of 548 was chosen as the research object. Without changing other geometric parameters, seven runners with diffe-rent blade setting angles were obtained by offsetting the runner blade. Based on experimental verification, the influence of blade setting angle on the hydraulic performance of micro axial flow hydraulic turbine was analyzed using the computational fluid dynamics technology. The results show that when the blade angle decreases, the head and output of the turbine increase under the same flow rate while the high-efficiency area shifts to the small flow area, and the range of efficient operation of the hydraulic turbine increases to a certain extent. With the increase of the blade setting angle, the head and output of the hydraulic turbine decrease, and the high-efficiency area shifts to the large flow area. The hydraulic turbine with an appropriately reduced blade angle can maintain better performance over a wide range of head(flow rate)variations. The highest efficiency of the hydraulic turbine with a placement angle of -4° reaches 82.13%, with the largest range of high-efficiency regions. This study can provide some reference for the design of micro axial flow hydraulic turbine runners.
2024 Vol. 42 (4): 350-357 [Abstract] ( 8 ) [HTML 1KB] [ PDF 6501KB] ( 126 )
358 Parametric study on improving the stability of axial-flow pumps with self-circulating casing
TONG Zhiting,YUAN Ye,ZHANG Zhimin,ZHANG Chao,*
In order to explore ways to effectively expand the stable operating range of axial-flow pumps, a single-channel steady numerical simulation of the self-circulating casing treatment was carried out on an axial-flow pump to analyze the influence of the circumferential coverage ratio, suction port position and throat height on the expansion and stability performance of water pumps, and to as well reveal the influence law and improvement mechanism of the self-circulating casing on the expansion and stability of axial-flow pumps. The results show that the self-circulating casing can effectively expand the flow range of the axial-flow pump, keeping the position of the suction port unchanged, increasing the circumferential coverage ratio and throat height can increase the flow margin, but the design point efficiency is reduced. The flow margin of the self-circulating casing with a throat height of 1.8 mm first increases and then decreases with the backward movement of the suction port position, and the efficiency first decreases and then increases, indicating that there is an optimal position above the blade tip. Within the scope of the study, the flow margin reaches a maximum of 5.93%, and the efficiency at the design point is reduced by a minimum of 1.12%. Through the self-circulating casing treatment, the area of the blockage area formed by the interaction between the blade tip leakage flow and the main flow above the blade tip is reduced, which is responsible for the extended flow range and increased efficiency of the axial-flow pump for small flow conditions. This study provides a reference for the expansion and stability of axial-flow pump under the end wall treatment of self-circulating casing.
2024 Vol. 42 (4): 358-364 [Abstract] ( 7 ) [HTML 1KB] [ PDF 5881KB] ( 86 )
365 Analysis of aeroelastic deformation of bionic airfoil wind turbine blades
CHEN Kun*,ZHAO Peiyao,FENG Wenhui,GUI Hongliang,HAO Zhenhua
In order to suppress the aeroelastic deformation of wind turbine blades, a modified design of the bionic owl′s airfoil for large wind turbines was proposed. The effect of the bionic airfoil on the aero-elastic deformation of the blade was analyzed by the unidirectional fluid-structure coupling method, and the mechanism of the bionic airfoil suppressing the aeroelastic deformation of the blade was elaborated by modal analysis and resonance response. The results found that there is an 11.05% reduction in the aeroelastic deformation of the bionic airfoil blade compared to the model blade. The bionic airfoil makes the blade pressure surface stress distribution trend change, and makes the maximum stress value of the blade pressure surface transfer from the middle of the blade to the leading edge. The bionic airfoil makes the pressure difference between the upper and lower surface of the blade increase, and the pressure value of the suction surface is about twice the original, so that the blade in the flapping direction to improve the resistance to deformation. At the same time, the aerodynamic performance of the blades has been improved. The bionic airfoil pattern increases the first to sixth order intrinsic frequency of the blade, the bionic airfoil pattern causes an 89.23% reduction in the resonant deformation of the blade in the flapping direction, and also reduces the resonant velocity and acceleration amplitude of the blade. Therefore, the bionic airfoil can effectively suppress the aeroelastic deformation of the blade, and its design method and conclusion can provide a new idea for the research of suppressing aeroelastic deformation of large wind turbine blade.
2024 Vol. 42 (4): 365-372 [Abstract] ( 7 ) [HTML 1KB] [ PDF 5052KB] ( 101 )
373 Finite volume method simulation analysis of combined hydraulic transients of pressurized pipe flow and open channel flow
WU Jinyuan,ZHOU Ling,*,HU Yinying,XU Yuyang
The finite volume method(FVM)of the second-order Godunov scheme was used to simulate the long-distance water conveyance system with pressurized and open channel sections. Firstly, the governing equations of pressurized pipe flow and open channel flow were respectively discretized according to FVM, the flux was calculated by the Riemann solver, and the MINMOD slope limiters were introduced to avoid spurious oscillations during data reconstruction. The virtual-boundary approach was presented to achieve a unified computation scheme for all the control volumes at the internal domain and boundaries. In an open channel calculation time interval, several pressure calculations were carried out, to realize the joint calculation of pressurized pipe flow and open channel flow. The model proposed in this paper was compared with the traditional method of characteristics(MOC)to verify the accuracy of the proposed model, and the sensitivity of the calculation time interval was analyzed. The results show that when the Courant number is less than 1, MOC will produce large calculation errors in both pressurized pipe flow and open channel flow, while FVM calculations are more accurate. The results of the combined hydraulic calculation of pressurized pipe flow and open channel flow were compared with that of the independent calculation of the pressurized section. The latter result is more conservative, which makes the economics of the construction design stage poor. Therefore, the joint calculation of pressurized pipe flow and open channel flow proposed in this study is of high necessity.
2024 Vol. 42 (4): 373-379 [Abstract] ( 8 ) [HTML 1KB] [ PDF 7071KB] ( 122 )
380 Progressive erosion of 90°elbow wall based on dynamic boundary
CHEN Yu,LI Rennian,*,HAN Wei,ZHOU Weiwei
The fixed boundary wear prediction method can only obtain the wear characteristics under the initial boundary state of wear, and cannot obtain the dynamic response of the flow field after wall failure. A method for predicting the progressive erosion of the sandy water flow-passage walls with dynamic boundary was proposed based on Computational Fluid Dynamics(CFD). The wall erosion morphology as well as the characteristics of flow field, erosion and particle impact of the 90° elbow at different erosion times were studied. the multiphase flow characteristics and wear evolution mechanism caused by the evolution of the wear morphology of the flow passage wall are revealed. The results show that in a 90° elbow with an inflow velocity of 6.3 m/s and the particle volume fraction of 0.35%, the erosion is mainly concentrated near the end(50°-90°)of the inner wall. And after 20 000 hours, the average erosion rate of the outer inner wall and inner wall is increased to about 2 times. The distribution of particle impact velocity shows a law of increasing first and then decreasing, and the maximum changes is 0.81 m/s. While the particle impact angle increases almost linearly, with an average maximum increase of 1.13°. Moreover, the impact velocity of particles in the erosion pits decreases, while the impact velocity at the edge of the erosion pit increases, indicating that the erosion range will further expand with the increase of erosion time. The research results provide a reference for the erosion protection of elbows.
2024 Vol. 42 (4): 380-387 [Abstract] ( 5 ) [HTML 1KB] [ PDF 63049KB] ( 112 )
388 Combined seal lubrication analysis under the influence of surface roughness and cavitation effect
ZHANG Yi*,XIONG Zijie,LI Dajian,XIONG Siyang,ZHONG Sipeng
The surface roughness and cavitation effect have a great influence on the sealing performance of the piston seal pair of fracturing pump. Based on the steady Reynolds equation, the elastohydrodynamic lubrication numerical model of the combined seal under the influence of asperity and cavitation effect is established. On the basis of numerical simulation, the finite volume method is adopted to solve the steady-state Reynolds equation to study the distribution of film thickness, film pressure and film velocity under the influence of surface roughness, and the influence of different reciprocating velocity and slip-ring surface roughness on the sealing performance. The results show that the dynamic pressure effect in outstroke is weak, and the cavitation phenomenon occurs near the air side of the contact area. Higher reciprocating speed is beneficial to reduce the leakage and friction resistance. When the slip-ring surface roughness increases from 0.8 μm to 1.8 μm, the net leakage and friction of outstroke increase by 180.4% and 11.17%, respectively. Therefore, higher reciprocating speed and lower roughness slip ring should be set in the working process to improve the sealing performance.
2024 Vol. 42 (4): 388-394 [Abstract] ( 5 ) [HTML 1KB] [ PDF 3683KB] ( 79 )
395 Characterization of vortex rope in draft tube of water turbine based on Omega vortex identification method
JIANG Yuhao,TANG Lingdi*
In order to study the vortex rope characteristics of the water turbine draft tube and the effectiveness of the Omega vortex identification method on the vortex rope of the draft tube, this paper compared the Q and λ2 criterion and the Omega vortex identification method on the vortex rope of the draft tube, and analyzed the vortex rope characteristics of the draft tube under different operating conditions based on the Omega method and the reduced dimensional Omgea method. The results show that: for radial water turbines, the Q and λ2 criterion, as well as the Omega vortex identification method can identify a clear and reasonable draft tube vortex by adjusting the threshold value reasonably, while the threshold selection interval of the Omega method is small and insensitive. The draft tube of the water turbine will have a long vortex rope in the flow condition, which is not conducive to the stability of the machinery. At the same time, using the reduced-dimensional Omega vortex identification method and the proposed vortex energy index, quantitative analysis of the monitoring surface of the tailpipe under different operating conditions was conducted to determine the area of high vortex concentration, as well as studying the energy dissipation patterns in draft tube. The results show that the area between the inlet and the bend of the draft tube has the highest vortex concentration, the highest energy dissipation and the most unstable flow pattern, which can provide a basis for optimizing the structure of this type of water turbine.
2024 Vol. 42 (4): 395-402 [Abstract] ( 7 ) [HTML 1KB] [ PDF 6258KB] ( 93 )
403 Study on shape optimization of energy dissipation structure in flood discharge bottom hole of hydropower station
ZHANG Yao,YIN Jinbu*,WU Xijie,WU Wei,GONG Gang
As one of the important components of the flood discharge of the dam body, the energy dissipation design of the bottom orifice has an important influence on the safety and efficienty of the project. In view of the problem that the energy dissipation area of a hydropower station is narrow and the tailrace comal of the left bank power station is easily affected, according to the idea of guiding the water tongue to the center of the stilling basin, the shape of the flip-flow guidance scheme and the surface flow diffusion scheme was modified. Finally, the recommended shape was the surface flow diffusion energy dissipater. The flow pattern, time-averaged pressure, pulsating pressure, velocity distribution, scouring characteristics and energy dissipation rate of the original design shape and the recommended shape were compared and studied by means of model test and numerical simulation.The results show that the energy dissipation effect of the original narrow slit scheme is good, but the mainstream of the water tongue is concentrated on both sides of the left and right banks, resulting in local scour on both sides. The surface flow diffusion scheme allows the discharge of water to form a free surface flow pattern, and rapidly diffuses to the whole river channel. The energy dissipation area is expanded, which effectively reduces the time-averaged pressure, pulsating pressure and bottom velocity of the bottom plate, with the velocity and pressure distribution becoming more uniform. The scour pit depth of the downstream river channel is reduced by 34%, and the scour range is reduced by 35%, which ensures the safe operation of the left bank power station. The recommended scheme can provide reference for similar projects.
2024 Vol. 42 (4): 403-409 [Abstract] ( 6 ) [HTML 1KB] [ PDF 15287KB] ( 97 )
410 Effect of fly ash on mechanical properties and pore structure of high-strength concrete
HAN Changjun,ZHOU Hailong*,CHEN Yan,ZHANG Xuepeng
To investigate the impact of fly ash replacement cement ratios on the strength and internal pore structure changes of manufactured sand high-strength concrete(MSC)and natural sand high-strength concrete(NSC), C80 high-strength concrete was designed with fly ash replacement cement ratios of 0, 10%, 15%, 20%, and 25%, respectively. Nuclear magnetic resonance(NMR)technology was used to analyze the evolution of concrete pores, and X-ray diffraction(XRD), diffe-rential thermal gravimetric analysis(DTA), as well as field emission scanning electron microscopy(SEM)technology were used to analyze the morphology and microstructure of hydration products in cementitious materials. The results show that the strength of MSC is higher than that of NSC at all ages, and the initial strength decreases with the increase of fly ash content. In the later stage, the strength of 10% fly ash concrete is the highest; 10% fly ash promotes the hydration process of cement and fills gel pores to reduce the generation of cracks, thus optimizing the internal structural pores of concrete and improves the overall compactness of concrete. Considering the influence of fine aggregate morphology parameters and fly ash substitution rate on concrete strength, a 28-day compressive strength prediction model for fly ash concrete was established based on the compressible stacking theory with good accuracy. The research can provide some reference for the high-quality application of fly ash high-strength concrete.
2024 Vol. 42 (4): 410-417 [Abstract] ( 5 ) [HTML 1KB] [ PDF 6630KB] ( 108 )
418 Analysis of hydraulic control pipeline characteristics of intelligent completion system
HE Dongsheng*,HE Qianlong,ZHANG Linfeng,ZHOU Guangheng
The continuously changing formation temperature in the well will have a great influence on the fluid flow in the hydraulic control pipeline of the intelligent completion system, but the existing continuous equation and motion equations cannot solve the fluid flow in the hydraulic pipeline under the variable temperature environment. Aiming to resolve this problem, according to the definition of the energy equation, this paper analyzed the fluid infinitesimal and the characteristics of No.32 hydraulic oil used, deduced a specific form of the energy equation, and then established the existing continuous equation and motion equation. A new set of equations was obtained, and the new set of equations was solved by using the method of characteristics(MOC)combined with MATLAB software. The simulation results under some constant temperature conditions and two continuous variable temperature conditions show that the new set of equations is more accurate than the old set of equations, which verifies the rationality and accuracy of the energy equation deduced in this paper. It shows that it can be used to calculate and solve fluid flow problems in hydraulic pipelines under constant temperature and variable temperature environments. And it can be extended to calculate and solve the hydraulic control pipeline of intelligent completion system, and judge the open state of downhole flow control valve of intelligent completion. The research results in this paper can provide a reference for hydraulic control of intelligent completion systems.
2024 Vol. 42 (4): 418-425 [Abstract] ( 8 ) [HTML 1KB] [ PDF 2272KB] ( 76 )
426 Influence of different structural parameters on droplet size of atomizing nozzle
FENG Jingzhi,ZHU Xingye,*,HUA Shan,QIAN Zhao,LIU Junping
Aiming at solving the problems of high atomization pressure and small atomization range in the development of current atomization nozzles, a new atomization nozzle was designed, and its atomization characteristics were analyzed. A laser particle size tester was used to investigate the effects of pressure(0.15~0.30 MPa)and different apertures(0.3~0.9 mm)on the nozzle atomization cone angle, velocity field, and droplet size, to obtain the changed rules of flow characteristics of the flow field under different test conditions. It was found that under low pressure, the atomization cone angle is greatly affected by the nozzle outlet diameter, and the larger the outlet shrinkage angle, the better the atomization characteristics. The nozzle with a diameter of 0.9 mm can achieve a relatively wide range of operation when the ratio of nozzle cavity length to the hole is 1 and the outlet contraction angle is 75°. With the increase of working pressure, the maximum value of droplet velocity also increases significantly, but the pressure has little influence on the overall velocity distribution of the atomization flow field. The droplet diameter also increases with the increase of pressure, and the nozzle outlet diameter has a significant impact on the droplet diameter, but the larger the outlet diameter, the smaller the droplet velocity, and the smaller the atomization cone angle.
2024 Vol. 42 (4): 426-432 [Abstract] ( 10 ) [HTML 1KB] [ PDF 7936KB] ( 87 )

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徐云峰  张文涛 陈建华
谈国鹏  朱漪云 盛    杰


· National Research Center of Pumps

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