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Journal of Drainage and Irrigation Machinery Engin
 
2010 Vol.28 Issue.6
Published 2010-11-30
article
Article
461 Experiment on ejecting performance of automatic air ejecting two phase flow jet pump
Zhang Qiang， Tong Mingwei， Liu Bin
The most important influence factor of ejecting performance for eject pump is  area proportion. Experiment was carried out to research the relationship between area proportion and ejecting performance of jet pumps under different system pressure. The water quantity, ejecting air quantity and ejecting coefficient of the jet pumps with different nozzle sizes and area proportions were tested through experiment under the condition of different access water pressure, and the experimental values of ejecting air of eject pumps with different structure parameters in different conditions were obtained. The experimental results showed that the maximum value of quantity of water and ejecting air were 1 940 L/h and 1 090 L/h of the jet pump with 5.5 mm nozzle and 0.40 MPa system pressure, respectively, and the maximum value of quantity of water and ejecting air were 1 240 L/h and 1 280 L/h of the jet pump with 4.0 mm nozzle and 0.60 MPa system pressure, respectively. The ejecting coefficient increased with the access water pressure increasing. When a certain pressure was reached, the ejecting coefficient was invariable. When the system pressure was 0.40 MPa, the ejecting coefficients of jet pump with 5.5 mm and 4.0 mm nozzle were 0.56 and 1.07, respectively. Quantity of ejecting air and ejecting coefficient needs to be paid attention to in designing and applying automatic airejecting twophase flow jet pumps.
2010 Vol. 28 (6): 461-464 [Abstract] ( 2127 ) [HTML 1KB] [ PDF 324KB] ( 1683 )
465 Optimization algorithm of tetrahedral mesh for centrifugal pumps
Liu Houlin， Lu Mingzhen， Wu Jin， Tan Minggao， Dong Liang， Ren Yun
The type of badly shaped elements in tetrahedral mesh was summarized. The estimating criterion of the types of different badly shaped elements was proposed through the numerical calculation. With the criterion, the types, distributions and causes of the badly shaped elements in centrifugal pumps were analyzed，an error function was put forward and taken as the object function of the optimal algorithmbased smoothing by researching available functions of tetrahedral element quality and considering the edge mass restriction. The minimum of the error function could be obtained by using BFGS(broyden fletcher goldfarb shanno) method to smooth tetrahedral mesh． Finally, the improved optimizationbased smoothing, Laplacian smoothing and swapping technique were integrated to optimize the poorquality mesh elements generated by advancing front technique(AFT) method and Delaunay triangulation method．The practical application of the optimization algorithm for a centrifugal pump shows that the worst mesh elements can be eliminated and the whole mesh quality can be improved obviously．So the algorithm can be used well in tetrahedral mesh optimization of centrifugal pumps.
2010 Vol. 28 (6): 465-469 [Abstract] ( 2194 ) [HTML 1KB] [ PDF 366KB] ( 1609 )
470 Optimal design  of centrifugal pump with large power and high pressure
Wang Leqin, Ping Shiliang, Wu Dazhuan
Aimed at the requirements of centrifugal pumps with large power and high pressure, such as high head, large flow, high rotation speed, high operation reliability, and so on, some key technologies were studied through hydraulic model design, rotor dynamics design and safety design of high pressure devices. The hydraulic model of pumps was designed by applying CFD technology to optimize flow parts, meanwhile the influence of the tip clearance flow on the dynamics of the rotor systems was considered. In the design of rotor dynamics, the twist vibration characteristics of units shafting and critical speed were analyzed in order to ensure rotor rigidity design and unit operation reliability, especially, the “wet” critical speed analysis was introduced when pump practical operation conditions were considered. In the optimization design of highpressure shell based on stress classification, the theory of pressure vessel design was introduced and 3D numerical simulation was carried out. These key technologies have been successfully applied in highpressure pump with 3 800 kW power, which provides a reference  for development of centrifugal pump with large power and high pressure in domestic.
2010 Vol. 28 (6): 470-473 [Abstract] ( 2104 ) [HTML 1KB] [ PDF 325KB] ( 1753 )
474 Numerical simulation of boss structure and its impact on rotational flow selfpriming pump performance
Wang Chunlin， Ding Jian， Shi Yating， Lü Yayun， Li Changjun
The inner flow field of a rotational flow selfpriming pump was simulated based on large eddy simulation（LES）with threedimensional nonstructural mesh and finite volume method, and proper boundary conditions were determined according to this issue. The commercial CFD software Fluent was applied. The distribution of inner flow field within pump and boss region nearby was obtained. In order to study the influence of boss structure with different parameters, computation of performance prediction was carried out under several different operating conditions, and the performance curves were obtained. According to the numerical results, the relations between the inner flow field within boss region and the overall characteristics were investigated based on the performance curves. The influence of boss structure on performance was revealed by comparing the external characteristics with different boss parameters. It is found that boss structure has greater impact on head and efficiency, but lesser impact on shaft power. The optimal value of boss parameters can be obtained by use of CFD aided design and comparative analysis of performances with different boss structure parameters, which can provide a reference for pump optimal redesign.
2010 Vol. 28 (6): 474-478 [Abstract] ( 1993 ) [HTML 1KB] [ PDF 394KB] ( 1294 )
479 Hydraulic design and quadratic regression orthogonal experiment of deep well centrifugal pumps
Wang Hongliang， Shi Weidong， Lu Weigang， Zhou Ling， Wang Chuan
According to the research and development request of new deep well pump energysaving and materialsaving, test investigation was taken to increase the efficiency of deep well pumps by using hydraulic design of impeller, the modern CFD and the quadratic regression orthogonal test method. The experiment was carried out with two factors of outlet angle and outlet width. Ten impellers were designed through testing schemes of quadratic regression. The whole flow field of the twostage newtype deep well pumps at design condition was simulated by CFD, and the efficiency of each case was obtained. The effects of both outlet angle and outlet width on efficiency were investigated through quadratic regression orthogonal testing method. According to the calculation results, constrained quadratic regression equation of the efficiency was put forward. The result shows that it would be instructive to increase the hydraulic efficiency of newtype deep well pumps by using the impeller diameter maximum approach.
2010 Vol. 28 (6): 479-483 [Abstract] ( 2398 ) [HTML 1KB] [ PDF 299KB] ( 1551 )
484 A new type of Francis turbine applied in cooling towers
Zheng Yuan, Zhang Limin, Yin Yiwu, Li Xi
In order to save energy, a new type of Francis turbine with highspecific speed was developed to replace fan motor in the cooling tower equipped with a suitable reducer by numerical simulation and model test. According to the features of Francis turbine operation environment, metal trapezoidal volute and uniseriate ring guide vanes were applied in the structural design. The forms of vanes, blade stagger angle and the rotational speed were analyzed by numerical simulation. The negative curvature guide leaf form, the optimum rotational speed and blade angle are selected as the optimal plan. The model test results show that the highspecific speed hydraulic turbine developed meets the dimension requirement and has high efficiency and stable performance, which can be popularized and applied in the capable local places.
2010 Vol. 28 (6): 484-487 [Abstract] ( 2329 ) [HTML 1KB] [ PDF 268KB] ( 1616 )
488 Numerical calculation and optimal design of centrifugal pumpwith space guide vanes
Cong Xiaoqing, Wang Guanghui，Yuan Danqing, Jia Ziqiang
Based on Navier-Stokes equations and standard k-ε turbulence model, the threedimensional turbulent flow in a centrifugal pump with space guide vanes was numerically simulated by using a SIMPLEC algorithm. The internal flow field of a centrifugal pump with entire flow, annular space and space guide vanes under design condition was analyzed, and the experiment was carried out to examine the simulation results. The results showed that the pressure of suction surface of impeller blades near the inlet area was lowest and negative pressure appeared. Higher impact loss was found in the annular space between impeller and space guide vanes. The highspeed rotating fluid from impeller outlet flowed into the guide vanes through annular space, the velocity near the inlet of space guide vanes was high, and there existed secondary flow near the leading edge of the space guide vane suction surface. The calculation and experimental results coincided well, and the maximum error was less than 15% between the numerical calculation results and experimental data under the same flow，which was in the acceptable limits and proved the effectiveness of numerical calculation. The research results provide a theoretical reference for geometric parameters optimization of the space guide vanes.
2010 Vol. 28 (6): 488-491 [Abstract] ( 2896 ) [HTML 1KB] [ PDF 397KB] ( 1475 )
492 Numerical simulation and experiment of gasliquid twophaseflow field in labyrinth screw pump
Zhang Youchen, Yang Chunling, Li Jingzhong
The flow field of gasliquid twophase in a labyrinth screw pump was simulated by CFD software Fluent based on the mixture model of multiphase, RNG k-ε turbulent model and SIMPLEC algorithm. The experiment was carried out to examine the simulation results. The two phase flow field in the pump was studied by analyzing pressure, velocity and gas void distributions. The simulation results showed that the pressure in screw groove grew continueously, velocity of outside regions was bigger than that of inside, the gas void distribution in screw groove was uniformly. But higher gas void regions appeared at inlet and outlet area and blocking phenomenon easily occured. The experimental results prove the validity of the numerical calculation model. To some extent, the simulation results can reveal the evolution of the two phase flow, and provide references for researching the principle of the twophase flow field in pumps. The experimental results also prove that the pump has a good aeration effect. So the labyrinth screw pump can be used to replace traditional aerators.
2010 Vol. 28 (6): 492-496 [Abstract] ( 2256 ) [HTML 1KB] [ PDF 402KB] ( 1715 )
497 Flow resistance characteristics of valveless piezoelectric pump with three way diffuser/nozzle tube
He Xiuhua， Wang Jian， Yang Song， Bi Yushi， Zhuo Hongcai
For the disadvantage of inefficient of the traditional diffuser/nozzlebased valveless piezoelectric pumps, a new type of valveless piezoelectric pump with three way diffuser/nozzle tube was proposed through the advanced design by analyzing the flow characteristics of the traditional diffuser/nozzle tube. Based on the numerical simulation, the threeway diffuser/nozzle tube and traditional diffuser/nozzle tube was compared. The effects of the flow resistance property of the three way tube was analyzed by changing the structural parameters of the shunts, including the length L2, the angle φ, the cone angle θ2 and the width b2 of the shunts. Compared with the traditional tube, the results show that the λ which is the ratio of the reverse flow resistance coefficient to forward flow resistance coefficient as a function of Reynolds number, is higher under high Reynolds number. So the efficiency of the valveless piezoelectric can be increased. The optimum structural parameters of the threeway diffuser/nozzle tube differ greatly under different Reynolds number. The appropriate structural parameters should be chosen according to the actual working condition when designing.
2010 Vol. 28 (6): 497-501 [Abstract] ( 2394 ) [HTML 1KB] [ PDF 402KB] ( 1390 )
502 Large eddy simulation of transient turbulent flow in  Francis turbine
Huang Jianfeng, Zhang Lixiang, Wang Wenquan, Yao Ji
Numerical simulation of threedimensional transient turbulent flow in the whole flow passage of a Francis turbine based upon the Reynolds averaged N-S equations was conducted with the large eddy simulation (LES) technique on Smargorinsky model and sliding mesh technology. The steady flow data simulated with the standard k-ε  model were used as the initial conditions for the unsteady simulation. The large scale structures evolving in spatially and temporally were visualized by the software Fluent 6.3, using unstructured hybridgrid and PISO algorithm. The evolution details of the large scale structures such as eddy from generate to shedding in vane cascades and blade passages were well captured at special case. The results show that LES can well simulate transient turbulent flow in a Francis turbine with  complex geometry. The computational method provides some reference for exploring mechanism of eddy formation in a complex turbulent of hydraulic machinery.
2010 Vol. 28 (6): 502-505 [Abstract] ( 2556 ) [HTML 1KB] [ PDF 435KB] ( 2218 )
506 Probabilistic analyse of shaft based on APDL parametric modeling
Gong Enxiang1， Huang Mingke1， Wu Jianbo2， Ding Yana1， Pan Binghui1
Using probability design system(PDS) provided by ANSYS software, taking pump geometric dimensions， load， stress，elastic modulus and strength limit etc as random variables, and according to stressstrength interference theory, the limit state function was created. The 3D solid model was established by APDL parametric design. Considering the real load to the shaft， static stress calculation was conducted, and probability analysis file was created. The method of Monte Carlo simulation technique and Latin hypercube sampling method was used to calculate the shaft reliability. The result shows that the method can obtain higher precision of failure probability of the shaft and more convenient than the traditional design. A reliability assessment for HS1K alkali pump shaft was demonstrated as an example， and the probability distribution of the shaft stress was obtained. The reliability of the pump shaft is 99.75% in the confidence level of 95%. It shows that the ANSYS/PDS can provide a theoretical help for Manufacturers to improve product， and has some engineering application values.
2010 Vol. 28 (6): 506-509 [Abstract] ( 2226 ) [HTML 1KB] [ PDF 315KB] ( 1533 )
510 Flow field analysis of non Newtonian fluid in mixing tumbling box
Xie Jun1, Guo Hongliu2, Chen Wei1, Yin Xiaoqin1, Kuang Lihui1
According to the characteristic of concrete，which is of typical non Newtonian Bingham fluid, the constitutive equations and fluid mechanical model were set up. Based on finite element method and  k-ε model, the three dimensional flow field of readymixed concrete in mixing tumblingbox was calculated using Fluent software. The numerical simulation for streamline and axial output speed of flow field were obtained at the condition of mixing blade spiral angle of 73°. The actual concrete mixing situation in tumbling box was relatively truly reflected. Contrasted with other mixing blades with different spiral angles of 66° and 80°, the mixing performance and output speed with spiral angle of 73° was superior to other mixing blades, and it satisfied the requirements of  homogeneous materials, continuous feeding and low power consumption of mixing tumblingbox for mixing carriers. In the meantime, some comparison testing was done and the correctness of simulation was proved. The numerical simulation for the concrete of nonNewtonian Bingham fluid in mixing tumbling box shows that k-ε model based CFD method can be used for analyzing the mixing process of concrete in mixing tumblingbox.
2010 Vol. 28 (6): 510-514 [Abstract] ( 2430 ) [HTML 1KB] [ PDF 391KB] ( 1835 )
515 Hamiltonian model of nonlinear hydraulic turbine with elastic water column
Zeng Yun1, Zhang Lixiang1, Xu Tianmao2, Guo Yakun3
To bring the hydraulic turbine and hydraulic system into the theory frame of the generalized Hamiltonian and study the dynamic mechanism of its operation and control, the model of its Hamiltonian system was studied. The hydraulic dynamics with elastic water column in increment described by transfer function were improved into first order differential equations in relative value, and it connects with the differential equation of the guide vane opening to compose the affine nonlinear system of extended hydraulic turbine. By constructing the Hamiltonian function of hydraulic turbine, the affine nonlinear model of hydraulic turbine was converted to Hamiltonian system by adopting orthogonal decomposition realization, and it was realized into Hamiltonian dissipative forms by decomposing the structure matrix and designing the dissipative feedback. The variation of dissipative structure, feedback equivalence and energy flow in built Hamiltonian model were studied, the energy flow of Hamiltonian were consistent with actual system in description of generalized energy. Simulation indicates that the Hamiltonian function contains detailed main information of energy change of hydraulic turbine in transient, and is feasible. 
2010 Vol. 28 (6): 515-520 [Abstract] ( 2206 ) [HTML 1KB] [ PDF 441KB] ( 1639 )
521 Geometric optimization of mechanical sealswith porous sector sealing face
Peng Xudong, Wu Zhaohui, Meng Xiangkai, Lu Suibang
A two dimensional steady state Reynolds equation was solved by finite element method, which controls the fluid film pressure distributions between the faces of a mechanical seal with a porous sector sealing face. The expressions for the major sealing performance parameters such as fluid film stiffness, opening force, leakage rate and stiffness to leakage rate ratio were presented. The effects of the textured geometric parameters on the sealing performance were analyzed under the given operation conditions and for a given sealed media, which mainly referred to porous sector number, the textured length ratios both in the circumferential direction and in the radial direction, the micropore radius and the micropore depth to diameter ratio. The geometricoptimization principle was presented for getting excellent sealing performance. The results show that the most important geometric parameter is the micropore depth to diameter ratio, and the textured length ratios both in the circumferential direction and in the radial direction are the next important ones when the textured geometric parameters and the micropore diameter are given. When the depth to diameter ratio is  0.003～0.007，and the textured length ratios both in the circumferential direction and in the radial direction are  0.3～0.5 and  0.45～0.85, respectively, such mechanical seals will offer excellent performance.
2010 Vol. 28 (6): 521-525 [Abstract] ( 1988 ) [HTML 1KB] [ PDF 381KB] ( 1467 )
526 Thermal calculation and analysis of bearings lubricating and cooling system of molten salt pump
Shan Chunxian，Yang Minguan，Wang Xin
The factors affecting the temperature rise of molten salt pump bearing lubrication and cooling system mainly come from bearing friction heat and heat transfer from high temperature molten salt. With the method of thermal nodes network the thermal balance equations were established for bearing lubrication and cooling system of molten salt pumps. Through the calculation of the bearing friction heat and the cooling system thermal resistance and heat transfer, the influence of shaft rotating speed, molten salt temperature, lubricating oil temperature and flow on bearing temperature was obtained. Higher pump rotating speed, the more bearing friction heat. When the shaft rotating speed increased from 500 r/min to 1 500 r/min, the bearing temperature was raised about 20 ℃. When the molten salt temperature was less than 400 ℃, its influence on lubrication system was lesser. When the molten salt temperature was higher than 550 ℃, the bearing temperature was raised rapidly. By keeping the lubricating oil temperature  below  40  ℃, and flow rate within 1.5~2.5 L/min, the best effect of the lubrication cooling could be  achieved.
2010 Vol. 28 (6): 526-530 [Abstract] ( 2355 ) [HTML 1KB] [ PDF 387KB] ( 1492 )
531 3D numerical simulation on unsteady turbulence flow in axial flow pump system
Feng Weimin, Song Li, Zuo Lei, Yuan Bo
In order to analyze inner flow transient performance of an axial flow pump, based on the  unsteady  incompressible flow governing equations and the RNG  k-ε turbulence model, the SIMPLEC method and sliding mesh technique were used to numerically simulate the 3D turbulent flow of the full passage in a vertical axial flow pump within a complete rotating cycle. The interaction between pass flow parts was taken into consideration. The type of pump was 4000ZLQ53.5-6.6JS. The pressure, velocity and vortices distributions on the interaction surface were given under the conditions that blade angle was zero and the discharge was 53.5 m 3/s. The results show respectively the variation of flow field  characteristics  in the impeller, and full flow passage in one rotating cycle. Numerical simulation results were obtained through comparative analysis on the distribution on the interaction surface. By introducing dynamic performance prediction, doing time average and comparing the results of dynamic performance prediction with test data from a pumping station, the method proves to be credible. It is indicated that the 3D unsteady turbulent simulation is effective for understanding the axial flow pump flow field, as well as the interaction mechanism.
2010 Vol. 28 (6): 531-536 [Abstract] ( 2023 ) [HTML 1KB] [ PDF 572KB] ( 1666 )
537 Study on hydraulic characteristics of vertical pipe inlet/outlet of pumped storage plants
Cheng Weiping, Hu Yunjin, Zhang Junjun, Mao Genhai
The 2D slip physical hydraulic model and axisymmetric numerical models were applied to investigate the wake flow direction of the vertical pipe inlet/outlet outflow. The results of the 2D model experiment and the axisymmetric numerical simulations showed that the outflow of vertical pipe with the cover plate performed as jet flow, and the direction of wake flow changed with the water level. The wake flow would shift to the surface layer when the water depth was small and it would turn to the bed when the water depth was high.The 3D model experiment showed that the outflow head loss coefficient was 0.61 with an antiswirl plate mounted above vertical inlet/outlet,and the factors were about 0.44～0.48 for other types of structures of statewide antiswirl beam,flat antiswirl beam or non antiswirl beam.The inflow head loss factors were about 0.4 for all types of intakes.The model experiment results also suggested that it was able to provide uniformity flow with pipe diffuse angle of less than 9°. An individual big spiral vortex appeared above the inlet structure during the inflow model experiment under the conditions of high water level. As the water level went down, the big spiral vortex would collapse into several small ones, and the number of spiral vortexes was same as the number of the guide walls.When two intakes were working at the same time,spiral vortexes would interact,one was dextrorotatory and another was levorotatory.
2010 Vol. 28 (6): 537-542 [Abstract] ( 2014 ) [HTML 1KB] [ PDF 500KB] ( 1485 )
543 Impact of oxygation on soil respiration and crop physiological characteristics in pineapple
Chen Xinming, Jay Dhungel, Surya Bhattarai, Manouchehr Torabi, David J Midmore
Oxygation refers to irrigation of the crops with aerated water, air injection using the venture principle or the supply hydrogen peroxide in the root zone, by using subsurface drip irrigation(SDI) system. This research investigated the potential of oxygation to enhance soil respiration, plant growth, yield, and water use efficiency(WUE) of pineapple in field experiments. The field experiment， compared Mazzei air injectors and control and treatments(oxygation or not)，were randomized and  replicated seven times in pineapple. In the experiments, soil water content and CO2 concentration in root zone of pineapple did not differ significantly between oxygation and not. But soil respiration increased by 100%, for oxygation compared to control at the same depth. There were significant effects of oxygation on pineapple fresh biomass, dry matter and industry production, and the harvest index. The irrigation water use efficiency(WUE) was not significantly improved, the WUE values in oxygation treatments were somewhat greater 4.3% compared with the control. However, the yield  and some quality parameters were significantly improved, the total fruit yield and marketable yield increased by 17.3% and 4.3%. Our data suggest that the benefits of oxygation are application for field crop.
2010 Vol. 28 (6): 543-547 [Abstract] ( 2587 ) [HTML 1KB] [ PDF 431KB] ( 1529 )
548 Performance test and force analysis of pressure regulator used in irrigation system
Yan Haijun, Yao Peipei, Wang Min
In order to study the relationship between the pressure regulating properties and the structural parameters of pressure regulator used in irrigation system, tests on the pressure regulating properties of seven low flow types of pressure regulators integrated with springs were conducted. The relationship between the spring parameters and the preset outlet pressure, and the forces acting on the builtin moving parts were also analyzed. The results showed that pressure regulator with lower preset outlet pressure has higher performance of regulating. The difference between measured critical working pressure and preset outlet pressure increases with the preset outlet pressure and is not equal to a constant of 0.034 MPa. As the preset outlet pressure increases, the spring stiffness constant increases with a larger spring diameter and a shorter spring natural length. Both the initial and maximum spring forces are in positive linear relationship with the preset outlet pressure. As well, when the regulating part moves toward the inlet of the pressure regulator, the ratio of spring force to hydrostatic pressure exerting on the outlet crosssection of the regulating part increases with an average from 57.9% to 66.5%, and the sum of friction force of the sealing part and the deformation force of rubber diaphragm decreases with an average from 39.9% to 31.3%.
2010 Vol. 28 (6): 548-552 [Abstract] ( 2455 ) [HTML 1KB] [ PDF 374KB] ( 1398 )
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