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Journal of Drainage and Irrigation Machinery Engin
 
2015 Vol.33 Issue.6
Published 2015-06-25

article
article
461 Numerical analysis on effects of nuclear main pump radial force under different eccentricities
Wang Peng, Yuan Shouqi, Wang Xiuli, Yin TingYun
In order to study the radial force of nuclear main pump, the prototype pump and the offset of the center of gravity of the nuclear main pumps had been investigated numerically by CFD calculation based on the RNG k-ε model. Results of performance of the nuclear main pumps, distribution of static pressure at the center section and the radial force features acting in the volute and impeller features had been obtained from the simulation, and were compared with the theoretical analysis. The results showed that the test results and numerical calculation were in good agreement in this paper thus the results of numerical calculation of radial force calculation model for nuclear main pump has certain accuracy. There is no great difference in distribution of static pressure within four schemes in the impeller and guide vane, but in the volute varies obviously, the static pressure distribution of different eccentricity were asymmetric, and the change of eccentricity had a certain influence on the internal and external performances of nuclear main pump. The radial force of nuclear main pump was minimum when it operated at the design point, but not equal to zero,the radial force was optimum when the eccentricity were 10 millimeter. By comparing the predicted radial force and the Stepanoff theoretical ones under different eccentricities it could be known that, the curves trend of the radial force under different eccentricities were consistent with the theoretical ones and the method of the numerical simulation verified the accuracy of the radial force calculated by the empirical formula.
2015 Vol. 33 (6): 461-466 [Abstract] ( 1171 ) [HTML 1KB] [ PDF 2133KB] ( 1113 )
467 Effects of particles on pressure fluctuation characteristics in centrifugal pump
Han Wei, Jin Yi, Li Rennian, Yue Ting, Quan Hui
To analyze the pressure fluctuation and the hydraulic force on the impeller between the rotor and stator in a centrifugal pump, the three-dimensional simulation was performed for the solid-liquid two-phase turbulent flow in a centrifugal pump with radial diffuser by the mixture multiphase model, the Large Eddy Simulation turbulence model and sliding mesh technology. The results indicate the pressure coefficients of both the water and solid-liquid flow decrease gradually with the increase of the flow rate; pulse also becomes regular gradually with the increase of the flow rate. On the interface of rotor and stator, the particle enhanced the high-frequency pressure fluctuation at the low flow rate, while at the high flow rate the particle weakened the high-frequency pressure fluctuation. In the rotor, the particle weakened the high-frequency pressure fluctuation at the low flow rate, while at the high flow rate, the particle enhanced the high-frequency pressure fluctuation. In the volute, the particle does not affect the pressure fluctuation, while in the tongue the particle enhanced the high-frequency pressure fluctuation. On the interface of the rotor and stator, the minimum impact of particles on pressure pulsation amplitude is 1.4Q, while the maximum is 0.2Q; in the rotor, the minimum impact of particles on pressure pulsation amplitude is 1.4Q, while the maximum is 0.6Q; in the volute, the minimum impact of particles on pressure pulsation amplitude is 1.0Q, while the maximum is 0.2Q; in the tongue, the minimum impact of particles on pressure pulsation amplitude is 1.0Q, while the maximum is 0.2Q.
2015 Vol. 33 (6): 467-474 [Abstract] ( 1815 ) [HTML 1KB] [ PDF 2432KB] ( 1018 )
475 Pressure fluctuation in residual heat removal pumps
Yuan Jianping, Zhu Yuwen, Zhou Banglun, Xia Shuijing, Shen Chendong
In order to investigate the characteristics of pressure fluctuation in residual heat removal pumps, three-dimensional unsteady numerical simulations were conducted by the SST turbulence model in ANSYS CFX. The performance of the residual heat removal pump was obtained and compared with the experimental results. The pressure fluctuations at various monitoring points were measured and analyzed in time and frequency domains. The results indicate that the pressure fluctuations in impeller and diffuser change periodically. The period of the pressure fluctuation within impeller is 7. The pressure fluctuation is closely related with the blade number in diffuser, while the period within diffuser is 5 and the fluctuation is strongly linked with the blade number in impeller. The amplitudes of pressure fluctuation at inlet, middle area and outlet of the impeller are 0.018 23, 0.106 76, 0.177 51, respectively. The amplitudes at inlet, middle area and outlet of the diffuser are 0.095 56,0.076 02,0.012 44,respectively. The amplitudes within impeller increase gradually from the inlet to outlet but the transformation law within the diffuser is opposite. The main frequency of pressure fluctuation within impeller which is dominated by the rotation speed is 7fp. The fluctuation is increasingly affected by the diffuser from the inlet to outlet. The main frequency at the inlet of diffuser is 15fp, while the others are 5fp. The fluctuation frequency within the diffuser is determined by the blade passing frequency. The fluctuation is decreasingly affected by the impeller from the inlet to outlet of the diffuser. The main frequency within volute is 35fp, which means that the fluctuation within volute is determined by the blade passing frequency and related with the blade number of diffuser.
2015 Vol. 33 (6): 475-480 [Abstract] ( 1369 ) [HTML 1KB] [ PDF 2067KB] ( 1051 )
481 Analysis of unsteady flow in flow-ejecting self-priming centrifugal pump based on LES
Wang Yang, Cui Yurui, Wang Kai, Wang Weijun, Li Guidong, Yin Gang
In order to study the characteristics of unsteady flow in flow-ejecting self-priming centrifugal pump, a self-priming centrifugal pump equipped with a jet in the front of impeller inlet was selected in the paper. The unsteady flow field was simulated based on LES turbulence model after steady calculation. The fourth cycle is considered as convergent and is used to analyze the pressure fluctuation data of all monitoring points and static pressure distribution in this cycle. Frequency domain characteristics of monitoring points are analyzed by FFT. The results show that the minimum pressure area is located in jet device and the maximum pressure area is in pump cavity. The maximum frequency value of each monitoring point within the impeller is 290.06 Hz. There are a few errors of frequency at monitoring points calculated by numerical simulation and theory. Pressure pulsation is mainly in the low frequency range of fn-3fn.
2015 Vol. 33 (6): 481-487 [Abstract] ( 1027 ) [HTML 1KB] [ PDF 2030KB] ( 1085 )
488 Internal and external characteristics of axial-flow pump based on coupling CFX with Workbench
Dong Xinghua, Guo Yanlei, Bi Zhen, Li Yibin, Cheng Xiaorui
To study the effects of coupling on the internal and external characteristics of the large submersible axial flow pump, the method of coupling CFX with Workbench was adopted to calculate the rotor components of pump in two-way coupling. The external characteristic and pressure fluctuation of large submersible axial flow pump in consideration of coupling effects or not were computed. Then the effects of coupling on macroscopic external characteristic and microscopic pressure fluctuation were ana-lyzed. Compared to those not by the coupling effects, both the efficiency and head by the coupling effects decrease by 1% or so. At the same time, the coupling effects could influence pressure fluctuation in the pump. To this pump, the coupling effects make no difference to the variation trend of pressure fluctuation. However, the amplitude corresponding to different frequencies would increase slightly. The closer the monitoring point is to the tip of impeller inlet, where the maximum deformation exists, the larger the amplitude of pressure fluctuation increase is;on the contrary, it is smaller.
2015 Vol. 33 (6): 488-493 [Abstract] ( 1612 ) [HTML 1KB] [ PDF 2405KB] ( 1252 )
494 Threedimensional CFD simulation of inlet structure flow in pumping station based on Eulerian solid-liquid twophase flow model
Mi Zihao, Zhou Daqing, Mao Yuanting
Sediment deposition in the pumping station has a huge negative impact on unit operation. The threedimensional CFD method has been used to simulate inlet structure flow in pumping station based on the Eulerian solid-liquid twophase flow model. The numerical results of the preliminary scheme show that sediment deposition occurs in the forebay of pumping station because of poor flow pattern therein. In order to improve hydraulic configuration in the forebay, one modified measure reconstructs water diversion weir shape, and another measure sets a water retaining sill in the approach channel. The simulation results of the modified scheme prove that back flow in the forebay has been eliminated and the sediment deposition region has also been reduced.
2015 Vol. 33 (6): 494-498 [Abstract] ( 915 ) [HTML 1KB] [ PDF 2953KB] ( 606 )
499 Effect of ferrite on ammonia nitrogen removal of rural sewage treated by activated sludge
Wan Shuxing, Li Jirong, Du Fuyi, Ma Xinhua, Xie Qingjie
In order to increase the microbial activity and the degradation efficiency of sewage of activated sludge, Ferrite enhanced activated sludge process was taken as a new wastewater biological treatment method based on magnetic effect. An appropriate amount of cheap ferrite magnetic powder were added into the conventional activated sludge process reactors to improve the microbial activity, MLSS, the removal efficiency of NH3-N from wastewater treatment and the deposition rate of activated sludge. The results show that after adding ferrite to the bioreactor, the start-up time for the reactor was cut down by 2 d; when the dosages of ferrite were 375 mg/L and 2 500 mg/L, the removal rates of NH3-N were increased by 26% and 27%,respectively. Meanwhile, the hydraulic retention time was reduced by 1 h after adding ferrite to the bioreactor, and the optimum range of temperature and DO of the reactor were expanded. This method can serve as a new method for the rural sewage treatment.
2015 Vol. 33 (6): 499-503 [Abstract] ( 1122 ) [HTML 1KB] [ PDF 1655KB] ( 1028 )
504 Pressure fluctuation characteristic of mechanical face sealing clearance of spiral groove in upstream pumping
Chen Huilong, Fu Jie, Li Shulin, Zhao Binjuan, Zou Qiang, Liu Jinfeng
To analyze the interaction of the rotating and static parts and the pressure fluctuation of micro clearance flow field in the upstream pumping mechanical seal, unsteady simulation was conducted to calculate the flow field on multiple working conditions based on the sliding mesh technique. The distribution of velocity and pressure inside the model at steady and unsteady states were studied. The time domain and frequency spectrum characteristics of the pressure fluctuation at different rotating speeds were also revealed. The simulation results were compared with the experimental results. Results show that internal flow field was displayed in detail through the simulation method and pressure pulsation at different speeds changes periodically because of the influence of rotating-static coupling. The pressure fluctuation,as a very important characteristic of the unsteady flow, is affected by the groove frequency and the shaft frequency.
2015 Vol. 33 (6): 504-509 [Abstract] ( 1184 ) [HTML 1KB] [ PDF 1965KB] ( 904 )
510 Test and analysis of water-lubricated bearing of seawater desalination pump
Ye Xiaoyan, Feng Yaoning, Wang Jing, Zhang Desheng, Hu Jingning
In order to study the hydrodynamic lubrication performance of the water-lubricated bearing and the stability of the system at different rotating speeds, the water-lubricated bearing test rig was designed based on the structure of desalination high-pressure pump. The fluid-structure interaction analysis of the bearing-rotor system was conducted by the Rigid Body Method. The journal orbit and bearing pressure fluctuations were monitored in the test, and the numerical simulation was conducted to verify the journal whirling orbit. The results show that there is a little lubrication water in the wedge gap,and the water film pressure is not stable and its distribution is discontinuous at a low rotating speed. With the rotating speed increasing, the lubrication water will increase, and the hydrodynamic effect will enhance, while the pressure distribution and curve will tend to be stable, indicating that the bearing-rotor system becomes stable. With the increase of rotating speed, the thickness of water film and the journal whirling amplitudes increase, and the journal whirling center lifts obviously. By comparing the result of numerical calculation with data from the test, the numerical calculation is proved to be a useful way to analyze the dynamic characteristic of the rotor-bearing system.
2015 Vol. 33 (6): 510-515 [Abstract] ( 1842 ) [HTML 1KB] [ PDF 4810KB] ( 1046 )
516 Effect of exterior cylinder slit wall on wavy vortex flow in gap of concentric cylinders
Zhu Fangneng, Liu Dong, Chao Changqing,Zhang Peng, Yan Jianhua
Numerical simulations were implemented by using CFD to investigate the wavy vortex flow inside concentric cylindrical annulus. The reliability of numerical method was verified by the experimental results of PIV. The research focused on the distribution of flow field and the fluctuation characteristics of wavy vortex flow in the plain and slit wall models. By studying the velocity field of the circumferential plane for two different models, the size of Taylor vortex and the fluctuation amplitude in axial direction of wavy vortex were analyzed. By comparing the radial velocity distribution in R-Z plane in two different models, the influence of slit wall on jet outflow effect was discussed. Meanwhile, the flow characteristic and the secondary flow phenomena in the slit regions were discussed. The results show that: the existence of slit wall changed the distribution of flow field inside the annulus and the fluctuation characteristics in axial direction of wavy vortex. An obvious secondary flow phenomena in the slit regions promoted the fluid mixing and diffusion between the slit region and the annulus, intensified the instability of wavy vortex flow inside the annulus.
2015 Vol. 33 (6): 516-520 [Abstract] ( 1011 ) [HTML 1KB] [ PDF 4002KB] ( 951 )
521 Numerical simulation for downwash flow field of small-size unmanned helicopter hedgehopping
Shi Qiang
In order to explore the downwash flow field characteristic of small-size unmanned helicopter hedgehopping, numerical simulations were conducted.The full-size physical model of the small-size helicopter was established by SolidWorks software. The outer flow field and meshing were established by Ansys Workbench software and ICEM software.Three-dimensional flow field of small-size unmanned helicopter hedgehopping was simulated by Fluent software.The results show that in the downwash flow field,the main movement form is vertical,accompanied by circumferential rotation and radial shrinkage.The maximum velocity appeared at the bottom of the location of 0.8R(R is the radius of the rotor)far from the axis of rotor rotation.With the vertical height declining,the maximum velocity and velocity gradient decrease.The acquired flow field can serve as a design referernce for a small-size unmanned helicopter.
2015 Vol. 33 (6): 521-525 [Abstract] ( 2239 ) [HTML 1KB] [ PDF 1747KB] ( 1646 )
526 Development and application of irrigation and drainage equipment system
Jin Qiu, Xu Shanshan, Xia Meiling
The research status of the field of agricultural irrigation and drainage at home and abroad, and the features of current common irrigation and drainage device were analyzed. To meet with the urgent needs of water-saving irrigation and controlled drainage equipment in China, the integration of irrigation and drainage equipment system was proposed. This system, which depended on the demand for water table of crops in different periods, made good use of rainfall and irrigation, accurately controlled water table of irrigation and drainage for paddy fields, and solved the problem that current irrigation and drainage equipment could not simultaneously achieve automatic control of irrigation and drainage. The results show that test area for paddy field integration of irrigation and drainage system increased 150 mm use of rainfall, rainfall utilization ratio increased by 21%, irrigation rate decreased by 21% and rice yield increased by 4.3% per mu compared to the control area. The system could improve the fertilizer utilization ratio and decrease agricultural non-point source pollution. So it is convihcible that the system can bring considerable economic, ecological benefits and wide applications.
2015 Vol. 33 (6): 526-530 [Abstract] ( 1219 ) [HTML 1KB] [ PDF 1425KB] ( 1054 )
531 Farmland irrigation of city sewage treated by aerobic granular sludge
Yan Ailan, Qi Yiting, Zheng Zhijin
The irrigation possibility of city sewage treated by aerobic granular sludge was explored. Results show that after the sewage was treated by aerobic granular sludge, the removal rates of CODcr and BOD5 in its effluents were 60% and 55% respectively; the removal rates of nitrogen and phosphorus were 50% and 53% separately;the removal rate of heavy metal was very high. The content of cadmium in the effluents was less than 1.0?10-5 mg/L. The Farmland Irrigation Water Quality Standard, whose value is less than 0.006 mg/L. Pb content in the effluents is 0.02 mg/L, less than the standard value of 0.1 mg/L. And the contents of other heavy metals, such as zinc, copper, mercury, chromium in the effluents were also much lower than the content values in the standard. So, the effluents of city sewage treated by aerobic granular sludge could be applied to farmland irrigation, and the indexes of CODCr,BOD5 nitregen,phosphorus,and other heavy metals in the effluents fully meet the requirements of the standard of the Farmland Irrigation Water Quality.
2015 Vol. 33 (6): 531-535 [Abstract] ( 865 ) [HTML 1KB] [ PDF 1465KB] ( 1008 )
536 Effects of mulch drip irrigation on the form of rice root and physiological characteristics
Li Li, Chen Lin, Zhang Tingting, Yin Yong′an, Zhu Jiangyan, Zhao ShuangLing
In order to explore the change in the growth of rice roots by mulch drip irrigation, japonica type rice “T-04”and “T-43” were adopted to study the form of rice root,roots, activity and nitrate reductase activity in mulch drip irrigation. The results indicate that at the depth of 20 cm,the length, surface area, volume and diameter of roots in mulch drip irrigation are all higher than those in the tradition basin irrigation. There is no significant difference at the depth of 40 cm;the activity of root on rice shows the trend of raising first and depressing later,and the highest stage and the tillering stage of rice are different in different cultivars of rice.The roots′ activity in mulch drip irrigation is higher than that in the tradition basin irrigation in the jointing-booting stage,full heading stage and milk-ripe stage. The anti-aging ability of roots is higher than that in mulch drip irrigation.Nitrate reductase(NR)activity in mulch drip irrigation is higher than that in the tradition basin irrigation. There is no significant difference in the tillering stage and milk-ripe stage. There is significant difference in the jointing-booting stage and full heading stage.
2015 Vol. 33 (6): 536-540 [Abstract] ( 1076 ) [HTML 1KB] [ PDF 1275KB] ( 1042 )
541 Direct torque control and direct suspension force control of bearingless permanent magnetic slice motor
Zhu Huangqiu, Gu Yingyue
Solving the complicated problem of precise decoupling, the vector control strategy also brings a large amount of calculations to the control system. Therefore a novel direct torque and direct suspension force control strategy of a bearingless permanent magnetic slice motor were proposed. On the basis of mathematic model, the theory and method of direct torque control of traditional PMSM motor were applied to the torque control of BPMSM. The direct torque control subsystem was constructed. According to similarities between torque windings and suspension force windings, the thought of DTC was applied to the suspension force control subsystem, then the direct suspension force control subsystem was constructed. With the integration of the space vector pulse width modulation, a novelty double SVPWM direct control system of the torque and suspension force for the BPMSM was realized. The relevant control algorithm was presented. The control system was simulated with Matalab/Simulink, and the results showed that the application of direct control strategy simplified the control algorithm, restrained the torque ripples,achieved better static and dynamic performance.
2015 Vol. 33 (6): 541-546 [Abstract] ( 1954 ) [HTML 1KB] [ PDF 2309KB] ( 1096 )
547 Review for sensorless detection technology applied in centrifugal pumps
Luo Yin, Sun Hui, Lu Jiaxing, Yuan Shouqi
In order to further research the application of sensorless detection technology in operation detection of centrifugal pumps, the background and research status of such a technology have been reviewed first. The sensorless detection technology is a kind of method of monitoring pumps through testing the stator current and voltage and analyzing motor torque signal by using induction motors as torque transducers. This could decrease the cost and make it convenient to use. The problems in traditional condition detection technology could be resolved, because most of centrifugal pumps are driven by induction motors. Currently,the research into the centrifugal pump detection technology focuses mainly on the diagnosis of the motor and its mechanical components, identification of centrifugal pump operation condition and extraction and analysis methods of motor output signals. Most of the researches focus on the theory and simulation. Then deficiency in the research of sensorless detection technology applied in centrifugal pump operation detection has been proposed, such as limited research of internal flow state of centrifugal pumps in literatures, less research of identification of specific flow state, little research on the extraction of various internal flow states characteristics in centrifugal pumps. Finally, the future tendency of such a technology has been proposed. The breakthraghof this technology lies in the research of unsteady characteristics of hydraulic load torque, response characteristics of transient hydraulic load torque in centrifugal pump shaft transmission and motor system, as well as extraction of various flow states characteristics in centrifugal pumps.
2015 Vol. 33 (6): 547-552 [Abstract] ( 1401 ) [HTML 1KB] [ PDF 1640KB] ( 1065 )
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