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Journal of Drainage and Irrigation Machinery Engin
 
2013 Vol.31 Issue.12
Published 2013-12-25

article
Article
1013 Comparisons between numerical calculations and measurements in vaned diffuser of SHF impeller
AnnieClaude BayeulLainé, Patrick Dupont, Giovanna Cavazzini, Patrick Cherdieu, Antoine Dazin, Gérard Bois, Olivier Roussette
2013 Vol. 31 (12): 1013-1020 [Abstract] ( 1246 ) [HTML 1KB] [ PDF 2054KB] ( 1189 )
1021 Experiment study of cavitation induced vibration and noise of guide vane mixed flow pump
Hu Fangfang, Chen Tao, Wu Dazhuan, Wang Leqin
The cavitation of mixed flow pumps can cause the pump performance decline, and accompanies with violent vibration and noise. To analyze the vibration and noise characteristics of a mixed flow pump and detect the cavitation, the vibration and noise signals were obtained by acceleration sensors mounted on different positions and a hydrophone in pump inlet. The experimental data were further a-nalyzed by a third times octave spectrum analysis method, and the characteristics of vibration and noise induced by cavitation were obtained. The results show that the vibration signals on pump inlet flange and on the case near pump inlet are more sensitive to pump cavitation, and it can be used for detecting cavitation; with the increasing of the flow rate, the frequency range of vibration signals for detecting the cavitation becames wider; the noise level induced by cavitation firstly gets higher with the frequency increasing, and the noise level reduces gradually when the frequence reaches the extreme value; the low frequency noise in pump inlet can be used to detect cavitation.
2013 Vol. 31 (12): 1021-1024 [Abstract] ( 1591 ) [HTML 1KB] [ PDF 1194KB] ( 1080 )
1025 Numerical simulations of turbulent flows in bulb tubular pump and performance predictions
Tang Xuelin, Chen Xiongsheng, Wang Fujun, Yang Wei, Wu Yulin
Owing to various characteristics of smooth flow pattern, less hydraulic losses and lower costs, tubular pumps are applied more and more widely in drainage and water diversion projects. Based on the standard k-ε and the Fluent software, the turbulent flows in a bulb tubular pump and the performance curves were investigated numerically. Under off-design operating cases, the streamline distributions inside the diffuser and the discharge passage indicate that there exist some secondary flows, which cause the hydraulic losses and the reduction in the tubular-pump efficiency. At large flow rates, there is a minimum of the static pressure near the inlet of the blade pressure surfaces due to the negative incidence angle. At small flow rates, the minimum of the static pressure happens near the inlet of the suction surfaces due to the positive incidence angle. At the best efficiency point(BEP), the minimum of the static pressure appears in the region behind the inlet of the suction surfaces. The calculated results show that the internal flow pattern is smooth at the BEP. Finally the overall performance curves including the head-discharge, power-discharge and efficiency-discharge curves were further obtained. The newly-designed pump model is validated by the comparisons between its predicted overall performance and the experimental data of the JGM-3 model. This research provides some important references for the design and optimization of a low-head bulb tubular pump.
2013 Vol. 31 (12): 1025-1029 [Abstract] ( 1280 ) [HTML 1KB] [ PDF 1899KB] ( 1026 )
1030 Approximate calculation and experiment of water pump shaft power based on loss analysis
Xi Sanzhong,, Zhang Tonglin,, Xiao Chongren, Hou Yongsheng, Gao Jiangyong
The loss analysis is one of the high precision methods for measurement of pump shaft power, and the procedures of measurement and data processing are very complex. Therefore, a discussion of an approximate calculation method was discussed in this paper. Based on theoretical derivation of loss analysis as well as the author′s many years′ experience in testing technology of water pumps,parts of the loss analysis process were simplified and simple measurement formulas were obtained. 3 submersible electric pumps with different power levels were randomly chosen to conduct a test in the national laboratory, and then the experimental results were compared with the theoretical calculation results. Comparison results show that the pump shaft power calculated by the approximate formula is very close to the result by loss analysis method; the average deviation between two methods for 3 pump shaft po-wer(actual output power of motor)is not more than 0.15%. The loss analysis can be used for the calculation of actual output power and efficiency of the pump motor for electric submersible pump in factory test, and the accuracy of this approximate calculation method is verified.
2013 Vol. 31 (12): 1030-1033 [Abstract] ( 1120 ) [HTML 1KB] [ PDF 1095KB] ( 1331 )
1034 Analysis of force acting on hydraulic blade regulating mechanism of axial-flow pump during adjusting process
Chen Hongxun, Zhang Weiyong, Pan Zhijun, Lu Weigang, Li Bin
In order to study the force acting on hydraulic blade regulating mechanism of an axial-flow pump during adjusting process, experiment and simulation had been done. On one hand, a measure experiment was taken with an axial-flow pump in Jiangdu pumping station. To calculate the force acting on the tie rod, it was necessary to measure the pressure of the upper and lower cylinder of servomotor piston during blades adjusting from-6 degree to+2 degree. The result shows that the regulating force gradually decreases with the increasing of the blade angle. On the other hand, a three dimensional simulation of turbulent flow in the axial-flow pump model was performed. Based on the simulation, hydraulic moment, centrifugal moment and friction moment acting on blades adjusting from-6 degree to+2 degree were calculated as 0.2 degree to be an increasing unit. We found that hydraulic moment and centrifugal moment will work together to make the blade to rotate in the closing direction. Then the regulating force was calculated on the basis of the three resistance moments. Comparing numerical solution with experimental values, it can be found that the two results has the same property that the regulating force decreases as blade angle increases, and both the force curves are approximately linear. This work provides a reference for the design of hydraulic blade regulating mechanism of axial-flow pumps.
2013 Vol. 31 (12): 1034-1038 [Abstract] ( 1485 ) [HTML 1KB] [ PDF 1412KB] ( 1233 )
1039 Application on polyhedral mesh in numerical simulation of internal flow in centrifugal pumps
Yuan Jianping, Hong Feng, Heng Yaguang, Zhou Banglun, Mao Shuiping
Aiming at the technical defects of calculation efficiency and discretization accuracy in the numerical simulation of internal flow in centrifugal pumps by using unstructured tetrahedral mesh, the flow field within a XA65/20 single-stage and single-suction centrifugal pump under design and off-design conditions was simulated with the software Ansys Fluent 13.0 using polyhedral mesh generated by agglomeration multi-grid method and unstructured tetrahedral mesh. The static pressure, velocity and turbulent kinetic energy distribution of the interior flow field were obtained and analyzed. In addition, the performance of the model pump was experimentally studied, both the head and efficiency of the pump predicted numerically were compared. The results show that the calculation based on polyhedral mesh has higher convergence speed, smoother residual curves and lower computer memory requirement. The pressure cloud and turbulent kinetic energy distribution are more uniform. The comparison between numerical and experimental results verifies the feasibility and accuracy of polyhedral mesh. In the angles of mesh setup time, computational expense and numerical diffusion, polyhedral mesh can be applied in the numerical simulation of internal flow in centrifugal pumps.
2013 Vol. 31 (12): 1039-1044 [Abstract] ( 1479 ) [HTML 1KB] [ PDF 4876KB] ( 1632 )
1045 PIV orthogonal measurement for internal flow pattern within centrifugal pump impeller
Zhou Zhengfu, Chen Songshan, He Zhongning
According to orthogonal test requirements, nine low specific speed centrifugal impellers with deviated splitter vanes were designed and manufactured. The orthogonal factors are the splitter vane suction diameter(D′), the inlet deviated angle(θ1)and the outlet deviated angle(θ2). Each factor takes 3 levels. Under the design speed(1 250 r/min), the internal dynamic flow patterns inside each impeller have been measured using PIV system under 4 different operating modes. The characteristics and the distribution pattern of the relative velocity vector field in the impeller were revealed. The results show that the flow in the impeller is asymmetric and non-uniform. Specifically, relative flow velocity near the suction surface is higher than that near the pressure surface. The relative velocity near the suction surface is increasing along the forward direction, while that near the pressure surface is decreasing. There is a high-velocity zone at the front suction surface(inlet)and a low-speed one at the front pressure surface(inlet). The deviated splitter vanes shapes and locations have a significant influence on the flow field inside the impeller. There are large differences between different schemes. When D′ is moderate, θ1 is bigger and θ2 is suitable, the flow field inside the impeller is better. The law revealed in the overall characteristic test is also similar with the PIV test.
2013 Vol. 31 (12): 1045-1048 [Abstract] ( 1622 ) [HTML 1KB] [ PDF 14577KB] ( 776 )
1049 The minimal trapped-oil pressure of expansion stage in external gear pump
Li Yulong
To overcome the limitations of testing and simulation, an analytic formula on minimal trapped-oil pressure in an external gear pump was tentatively established. For the expansion phase of trapped-oil, both cases of small backlash value and large backlash value, the long hole flow formula was applied to calculate the differential pressure flow through backlash. The leak path was simplified to calculate the axial leak flow from trapped-oil zone. The minimal trapped-oil pressure was calculated in the transient position that the expansion ratio of trapped-oil volume was equal to trapped-oil leak flow, that is to say, the change ratio of trapped-oil pressure with time was zero. The calculated results were then compared with the experimental results of the existing literature. The results show that, the position of minimal trapped-oil pressure was around the opening of relief groove, when in the inside, the negative minimal trapped-oil pressure would occur; while in the outside, the minimal trapped-oil pressure would approach closely the inlet-pressure; the minimal trapped-oil pressure was contributed by the outlet-pressure and rotation speed, among which, the minimum trapped-oil pressure was in a negative linear relationship with speed and a positive linear relationship with outlet-pressure; the overall offset of two relief grooves to inlet side was reasonable, etc. It can be finally concluded that, with the established analytic formula, the minimal trapped-oil pressure and its position can be promptly found without going through a large number of processes. Thus, the accumulated errors from process simulation are reduced and the minimal trapped-oil pressure is more accurate.
2013 Vol. 31 (12): 1049-1055 [Abstract] ( 1583 ) [HTML 1KB] [ PDF 2079KB] ( 1068 )
1056 PIV test on hump phenomenon of low specific speed centrifugal pumps
Ma Haochen, Ding Rong, Yang Dongsheng
The hump in performance curve of low specific speed centrifugal pumps affects the reliability obviously, which is still not solved today. In order to study inner flow mechanism of the hump, two hydraulic models are designed according to the same design requirements, in which scheme 1 has hump phenomenon and scheme 2 has no hump phenomenon. The performance of the two models is tested to validate the design. Then the internal flow of two model pumps are tested and analyzed by particle image velocimetry(PIV)system. The results show when performance curve appears hump, low speed area at the pressure side of the impeller blade increases rapidly, and vortex appeared at blade pressure surface of several channels. In the gap between impeller outlet and volute base circle, the flow rate of recirculation increases. The velocity difference between the impeller outlet and base circle of the volute also increases significantly, which results in increase of the hydraulic loss in the pump and causes hump phenomenon of the performance curve. The research results of the study can provide theoretical references to control the hump phenomenon of low specific speed centrifugal pumps.
2013 Vol. 31 (12): 1056-1060 [Abstract] ( 2065 ) [HTML 1KB] [ PDF 2475KB] ( 1380 )
1061 Improved Suter-transformation for complete characteristic curves of pump-turbine
Zheng Xiaobo, Tong Huanzhen
The complete characteristic curves of pump turbines appear "S" type at both pump and anti-pump working conditions. The multi-value characteristic of unit discharge and unit moment of the curves due to crossover and overlap phenomena can cause inconvenience for transition process analysis. Applying the method of improved Suter-transformation, the complete characteristic curves of the pump turbine can be transformed into two groups of periodic variation curves in the four quadrants, namely the WH(x,y)and WM(x,y)curves. The complete characteristic curves of the pump turbine were carried out for transformation based on the same curve characteristic of existing data, then the transformed fitting WH curve and WM curve were obtained by adopting the mathematical model of least square surface. Therefore, a three-dimensional surface was achieved containing the two curves. The WH curve and WM curve after transformation using improved Suter-transformation are smoothing and approximately parallel to each other, and therefore the multi-numerical values and nonuniform distribution defects of Suter-transformation curves can be avoided. So, it is possible to eliminate the crossover and overlap characteristics under the pump and the reverse-pump conditions, and improve the nonuniform distribution phenomenon at the two ends of the pump-turbine complete characteristic curve, thus it is conveni-ent for the transition process analysis of pump-turbines.
2013 Vol. 31 (12): 1061-1064 [Abstract] ( 3179 ) [HTML 1KB] [ PDF 1508KB] ( 1643 )
1065 Fault diagnosis of hydro turbine regulation system based on PCA-SDG
Liu Minghua,, Nan Haipeng, Yu Xiangyang
The method of fault diagnosis based on signed directed graph(SDG)was presented. The SDG model and inference rules for closed loop control system were established. For hydro turbine regulating process, the model of fault diagnosis and inference rules based on SDG was established by an experience approach. The principal component analysis(PCA)method combined with SDG model was applied to solve the subjectivity problem in the process for determining the node symbols and the "combination explosion" problem of the node threshold. Firstly, PCA model was established based on system operating data, then the residual error statistics were constructed for fault detection. When fault occurs, contribution rate of each detection component on residual error statistics will be compared with the contribution rate of setting thre-shold value to obtain the qualitative symbols value of each detection component. The symbol value can be assigned to the corresponding node in the SDG model. Then, fault inference can be conducted according to the SDG inference rules to find out fault source. This PCA-SDG based fault diagnosis method was applied to analyze sensors diagnosis of hydro turbine regulating process, constant deviation fault of sensor was introduced to simulate, and the results prove that this method is practically feasible. 
2013 Vol. 31 (12): 1065-1071 [Abstract] ( 1521 ) [HTML 1KB] [ PDF 1210KB] ( 1247 )
1072 Depressurization stage number of disc in high pressure drop labyrinth control valve
Li Shuxun,, Hou Yingzhe,, Xu Xiaogang,, Hu Jian, Hao Jiaoshan
How to confirm depressurization stage number on disc is the key design problem for high pressure drop labyrinth control valve. According to the compressible fluid dynamic theory, the calculation formula of depressurization stage number on disc was deduced and analyzed. Numerical simulation of the internal flow in three path models with different stage number were performed by using commercial software CFX, and the distribution of pressure and velocity were obtained, while the changing curve were analyzed. The results show that increasing the stage number is beneficial to reach smooth depressurization and equally distribute pressure, as well as to reduce velocity and outlet energy. In addition, it′s useless to increase the stage number if the path model has been satisfied with the outlet energy criteria. This study could be used as a reference for design of labyrinth control valve.
2013 Vol. 31 (12): 1072-1076 [Abstract] ( 2683 ) [HTML 1KB] [ PDF 1372KB] ( 1600 )
1077 Analytical analysis of stiffness characteristics of aerostatic gas lubricating mechanical seal
Song Pengyun, Xu Hengjie
In order to further understand the stiffness characteristics of the aerostatic gas lubricating mechanical seal, an analytical expression of the gas film stiffness was deduced based on analytical method. The calculated results by the analytical expression are very close to the results obtained by differentiating the opening force curve-fitting equation. The gas film stiffness characteristics influenced by the orifice diameter, supplying gas pressure and process gas pressure had been analyzed by the analy-tical expression, and the 3D surface charts of the gas film stiffness influenced by gas film thickness and the supplying gas pressure or the process gas pressure had been obtained. The results show that the effect of orifice diameter on the stiffness is obvious and larger stiffness can be got when the orifice dia-meter is about 0.2 mm as to the seal investigated. The gas film stiffness increases with increasing of supplying gas pressure or boundary pressure ratio of the supplying gas pressure over the process gas pressure. Raising the supplying gas pressure or boundary pressure ratio can obviously increase the gas film stiffness. The gas film stiffness is increasing firstly and then reducing with the increasing of gas film thickness at the specific pressure or pressure ratio. There is maximum gas film stiffness as the gas film thickness reaches a certain value. The gas film stiffness will be larger when the gas film thickness is 3-6 μm as to the dry gas seal investigated.
2013 Vol. 31 (12): 1077-1082 [Abstract] ( 1929 ) [HTML 1KB] [ PDF 2229KB] ( 1388 )
1083 Hydraulic performance of new pressure-compensating emitter with large flow
Li Lingyuan, Zhu Delan,, Zhang Lin
In order to develop a new kind of large flow pressure compensation emitter for economic fo-rest, taking the advantage of Pro/E, the three-dimensional model of the emitter was completed, and the rapid laser-molding was used to manufacture the emitter. To analyze the effect of important structural parameters on hydraulic performance such as exponent and flow of pressure compensation emitter with large flow, diaphragm thickness, diaphragm hardness and foundation height were studied based on the orthogonal test. The results show that: foundation bed height and pressure compensating range have related correlation; diaphragm thickness has the largest influence on flow exponent, followed by foundation bed height and diaphragm hardness. Diaphragm thickness has the largest impact on flow q, fo-llowed by diaphragm hardness and foundation height. Large flow pressure compensating emitter with the best hydraulic performance is optimized with the structural parameters as follows: a thickness of 1.3 mm, a hardness of 50° and a height of 4 mm. This kind of emitter has pressure compensating ranges from 50 kPa to 400 kPa, while flow exponent is 0.055 1, and flow q is 13.10 L/h.
2013 Vol. 31 (12): 1083-1088 [Abstract] ( 1761 ) [HTML 1KB] [ PDF 1313KB] ( 1189 )
1089 Effects of straw mulching and plant density on water utilization of summer maize
Liu Quanru, Lang Kun, Zhao Dandan, Shen Jiayin, Li Quanqi, Han Huifang
To understand the mechanization of the efficient water utilization on summer maize, field experiments involving straw mulching with 0, 0.6 kg/m2(N and M, respectively)and plant density with 10.0, 7.5, 5.5(1, 2 and 3, respectively)plants per m2 were conducted. The effect of straw mul-ching and plant density on soil moisture content under different layer, grain yield and yield components was investigated, to discuss the potential of grain yield and WUE improvement by the optimized combination of straw mulching and plant density. The results show that the yield and WUE of M2 treatment are 1 255.44 g/m2 and 3.93 kg/m3, respectively, which are higher than other treatments. Evapotranspiration has no significant difference among different straw mulching treatments in the whole summer maize growing season. Straw mulching improves the 0-30 cm soil moisture content in medium growing stage under low density treatment, ear number, 1 000-kernel weight, grain,WUE by 8.67%, 3.73%, 8.04%, 16.88%,21.94%, respectively. The yield difference is the dominant factor to influence the WUE among different straw mulching treatments. The experiment indicates that the combination of straw mulching and suitable planting density can make summer maize water saving and high yield.
2013 Vol. 31 (12): 1089-1094 [Abstract] ( 1768 ) [HTML 1KB] [ PDF 1165KB] ( 1011 )
1095 Ground distribution of light and temperature under furrow irrigation methods and ridging directions
Li Caixia, Zhou Xinguo, Sun Jingsheng, Qiu Xinqiang, Li Xinqiang
An experiment was conducted to present distributions of the ground temperature and light under various furrow irrigation methods and ridging directions. Light-temperature within maize field in south-north and east-west ridging directions under alternate furrow irrigation and conventional fu-rrow irrigation methods were respectively studied by measurements of solar radiation and temperature in different positions of the field. The results show that ground solar radiation quantity within maize field in east-west ridging direction is of 23.05-122.48 W/m2 more than that in south-north direction. Compared with the same condition of ridging direction but under conventional furrow irrigation method, the average ground solar radiation quantity is of 80.23 W/m2 more than under alternate furrow irrigation method. The variations of ground surface temperature are in accordance with solar radiation. Daily mean ground temperature is of 0.60-3.46 ℃ higher in east-west ridging direction. And ground temperature is of 2.23 ℃ higher under alternate furrow irrigation method in the same ridging direction. Ground light and heat resources are fully exploited by taking advantages of east-west ridging direction and alternate furrow irrigation method. As a result, field temperature and light will be regulated by altering cultivation methods or irrigation methods to meet different crops requirements.
2013 Vol. 31 (12): 1095-1099 [Abstract] ( 1430 ) [HTML 1KB] [ PDF 1378KB] ( 1200 )
1100 Analysis on core authors of Journal of Drainage and Irrigation Machinery Engineering in recent 8 years
Xu Yunfeng, Zhang Wentao, Chen Jianhua, Tan Guopeng, Zhu Yiyun, Sheng Jie
Based on the CNKI, the statistic datum of article quantities, cited frequencies and download frequencies of the authors of Drainage and Irrigation Machinery Engineering from 2006 to June in 2013 were analyzed. 118 core-author candidates were selected by Price′s Theorem. 36 core authors and 18 core authors expanded were determined with the comprehensive index method, and the authors′ affiliations, geographical distribution, professional title, age and gender were statistically analyzed. The results show that: during the survey period, a total of 828 papers were published by 1 686 authors, and the average author number of each paper is 3.88. 572 authors, accounting for 32.38%, have published two or more paper. 118 core-author candidates, 7.00% of all authors, have published 61.71% of articles. The maximum of articles published by core authors and expanded is 42, while the minimum is 5. There are 31 core authors from Jiangsu University, representing 57.41% of all core authors, and 39 come from Jiangsu Province, accounting for 72.22%. 66.67% of core authors and expanded are professors, while 64.81% are from 28 to 50 years old, and male female ratio is 5.75∶1.
2013 Vol. 31 (12): 1100-1104 [Abstract] ( 1441 ) [HTML 1KB] [ PDF 1008KB] ( 1179 )
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