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Journal of Drainage and Irrigation Machinery Engin
 
2014 Vol.32 Issue.4
Published 2014-04-25

article
Article
277 Effects of non-uniform suction flow on performance and pressure fluctuation in axial-flow pumps
Shi Weidong, Zhang Guangjian, Zhang Desheng, Wu Suqing, Xu Yandong
To study the effect of inflow conditions on an axial flow pump, two different types of non-uniform inlet velocity distributions were established. By comparing with uniform inflow conditions, the effects of the non-uniform inflow conditions on pump performance, radial forces and pressure fluctuations were achieved by numerical simulations. Comparison of numerical simulation results and experimental values under uniform inflow verifies the accuracy of the numerical model. A comparative analysis of the effects on pump head, efficiency and radial force curves was performed under 0.7Q-1.2Q conditions. The variation of the axial flow pump performance and radial loads with the non-uniformity of the inlet velocity was obtained. Finally, based on the unsteady simulation, pressure fluctuations at impeller inlet, impeller outlet and guide vane exit at design condition were monitored, and the effects of two non-uniform inflows on pressure pulsations at three typical positions were achieved. The results show that by controlling the inflow situation, the hydrodynamic performance with non-uniform inflow is better than that with uniform inflow distribution.
2014 Vol. 32 (4): 277-282 [Abstract] ( 1787 ) [HTML 1KB] [ PDF 2031KB] ( 1354 )
283 Extraction of internal flow velocity in pump of hydrodynamic torque converter based on Hough transform
Chai Bosen, Liu Chunbao, Wang Weidong
The power transmission characteristics of hydrodynamic torque converter are highly influen-ced by internal flow structure. The external performance of hydrodynamic torque converter is determined by internal flow characteristics. It has important meanings to grasp the complex internal flow in hydrodynamic torque converter based on visualization of internal flow field and quantitative measurement of internal flow velocity. Research on internal flow mechanism of hydrodynamic torque converter can be improved through detailed and accurate experimental results. The internal flow field of the pump was measured based on particle image velocimetry(PIV)technology, and flow images on radial section of the pump were captured by CCD camera with single exposure, when motion information of tracer particles were recorded. Image features of tracer particle trajectory were identified by image processing techniques, and trajectories of tracer particles were extracted automatically based on Hough transform for line detection theory. By using the method above, flow visualization of the pump was achieved, and the efficiency of identification and quantification for flow velocity vector was improved. The results of PIV measurement can reveal the real physical flow phenomena and transient changes of internal flow field in the pump, and the theory and practice basis for performance prediction and ratio-nal design of hydrodynamic torque converter can be provided.
2014 Vol. 32 (4): 283-289 [Abstract] ( 1331 ) [HTML 1KB] [ PDF 2459KB] ( 1023 )
290 Numerical analysis on unstable flow of reactor coolant pump under small flow rate condition
Long Yun, Zhu Rongsheng, Fu Qiang, Yuan Shouqi, Xi Yi
For the study on hump phenomenon of an reactor coolant pump, three-dimensional modeling for the pump internal flow was done by Pro/E, and based on the Reynolds-averaged Navier-Stokes equations with the RNG k-ε turbulence model and SIMPLEC algorithm, the flow was calculated using the computational fluid dynamics software CFX. The results show that: the numerical simulation me-thod used is feasible to explain unsteady hump phenomenon of reactor coolant pump under small flow rate conditions. Pump outlet is located in the center of the pump shell, making the mainstream along the direction of rotation friction crashing with the liquid at the outlet, resulting in energy loss and lea-ding to the uneven distribution of the flow field. The symmetric structure of reactor coolant pumps, the complex vortex near inlet and outlet of impeller blades, secondary flow in guide vanes region and rotating stall are closely related to the formation of the hump. The reactor coolant pump running under small flow conditions will cause unstable flow, which can result in severe vibration. 
2014 Vol. 32 (4): 290-295 [Abstract] ( 1992 ) [HTML 1KB] [ PDF 4352KB] ( 1250 )
296 Numerical simulation of labyrinth screw pump with series combination by Fluent
Li Jiaojiao, Zhang Youchen
Three-dimensional modeling and grid generation was done with Gambit, and 3D single-phase flow field in a pump was calculated by means of multiple reference frame(MRF)method. Renormalization group k-ε two-equation turbulence model(RNG k-ε model)and semi-implicit method for pressure-linked equations(SIMPLEC)algorithm with CFD code-Fluent was adopted. A new structure of labyrinth screw pump was put forward, the effect of ring slots was discussed, and the optimal design parameters were chosen. The results show that pump performance can achieve the best with the ring slot width and depth of 4 mm and 3 mm respectively. Momentum and energy transfer in the pump were studied by analyzing the static pressure, velocity and turbulent kinetic energy distribution, and pump hydraulic performances of the two models were compared. The analytical results indicate that pressurization magnitude and pressurization rate of the new model pump is larger than the original one. The fluid velocity in the rotor is obviously higher than that in the stator, and mass and momentum exchanges coexist on the clearance interface between the rotor and stator. The pressurization rate relates to the turbulent intensity, and the greater turbulent intensity is, the greater pressurization rate can be obtained. Pump performance of the new model is better than the original one, and compared to the original pump, the new model lift head increases by approximately 3.42 m while the hydraulic efficiency increases by 0.85% under the optimum operating condition, and the new model pump efficiency is significantly higher than the original model when the flow rate is greater than that of the optimum operating condition.
2014 Vol. 32 (4): 296-301 [Abstract] ( 2268 ) [HTML 1KB] [ PDF 1905KB] ( 1252 )
302 Numerical analysis of pressure fluctuation of internal flow in submersible axial-flow pump
Zhang Yuxin, Wang Xiuye, Ding Peng, Tang Xuelin
The pressure fluctuation in flow field has important influence on the operation stability of axial-flow pumps. In order to precisely analyze the pressure fluctuation in submersible axial-flow pumps, the RNG k-ε turbulence model and SIMPLEC algorithm were adopted to investigate the three dimensional turbulent flow and the pressure fluctuation in an axial-flow pump. The calculated results show that the predicted performance curves of pump were in good agreement with the experiment. The maximum amplitude of the pressure fluctuation occurs at the inlet of the impeller, and the main frequency of the pressure fluctuation inside the pump is the same as the blade passing frequency when the pressure fluctuation behind the guide-vanes is dominated by low-frequency. From hub to tip of the blade surface, the low frequency components of the fluctuation decreases.On the pressure surface of the blade, the pressure fluctuation amplitude decreases from tip to hub and increases from inlet to outlet of the impe-ller. The fluctuation amplitude on the outer tip is 1.22 times higher than that on the hub at the inlet. On the suction surface, the pressure fluctuation amplitude on tip is 1.77 times of the hub at the inlet and is 0.92 times of the hub at the outlet of the impeller. The amplitude on the suction surface is significantly less than that on the pressure surface of the blade. At the inlet of the impeller, the maximum amplitude of the pressure fluctuation happens at 0.8Q flow rate which is about twice the value at the design flow rate. The above-simulated results can provide some references for further analyzing the pressure fluctuation of axial-flow pumps.
2014 Vol. 32 (4): 302-307 [Abstract] ( 1979 ) [HTML 1KB] [ PDF 1870KB] ( 1163 )
308 Pump station noise and governance
Yu Xiaomin, Lü Liang, Hu Deyi, Huang Dishan
Although pumping station noise is clearly defined in Pumping Station Design Standard, in most cases the noise exceeds the standard. In South to North Water Diversion Project, long pumping time makes the issue more serious. Effective methods were discussed and adopted on the basis of noise sources analysis. Firstly, the noise occurrence principle was analyzed, and according to the noise characteristics, optimizing electromagnetic circuit, selecting superior material, improving processing standards and so on were made in the aspects of design and manufacture to reduce noise from the basic level. Secondly, considering the units′ structure and arrangement, damping insulation blankets were used on the motor and runner shells to weaken the noise spread. Finally, sound-absorbing material and building acoustic space was applied at the station. As the prevention methods used together, the motor floor noise of pumping station is less than 85 dB, which is better than the nation′s specification and good for working environment.
2014 Vol. 32 (4): 308-311 [Abstract] ( 1214 ) [HTML 1KB] [ PDF 1484KB] ( 1371 )
312 Optimum design for tide curve in flood protection and drainage project in Jiangsu coast area
Yang Xing, Huang Junyou, He Yong, Wang Wei, Chen Wenmeng
In order to optimize the design of hydrological parameters for flood protection and drainage project in coast area, based on Gumbel-Hougaard Copula function and conditional probability theory, the correlation characteristics between high tidal level and low tidal level in the same tidal process line were analyzed, then a new method for design tide curve was proposed. Based on this method, consi-dering three return period conditions(T=20,50,100,200 a), the design types of tide were given at Lianyungang, Sheyangzha and Tianshenggang tide gauges in Jiangsu province as examples. Comparing with same multiple enlarging method and the improved same multiple enlarging method, the new me-thod considers sufficiently the correlation characteristics between high tidal level and low tidal level, therefore, it is more perfect in theory; the tidal range from the new method is significantly larger than from other methods, and from a security standpoint, other methods have some design risks; the new method can also be extended to other similar design of combination of hydrological variables.
2014 Vol. 32 (4): 312-318 [Abstract] ( 1707 ) [HTML 1KB] [ PDF 1724KB] ( 1156 )
319 Distribution of marine mineral resource and advances of deep-sea lifting pump technology
Xiao Yexiang, Yang Lingbo, Cao Lei, Wang Zhengwei
Ocean is a huge treasure rich in biotic and minerals resources as well as energy. Exploitation of marine resources is a new national strategic objective, and the pace of deep-sea mining needs to be accelerated. Due to poor working conditions, the requirements for mining equipment are so high that the research of mining system, especially for the lifting pump system is very important. The classification and global distribution of subsea mineral resources were described. The situation of deep-sea mining in China in detail was summarized. The lifting technology is an important part of deep-sea mining system, and the pipe lifting method is considered to be one of the most promising lifting me-thods, which includes hydraulic lifting, air lifting, light medium and heavy media lifting, et al. Slurry pump lifting and air lift pump lifting technology have been carried out in deep sea trials, proving that they have the best development prospects. Finally, the development of hydraulic lifting technology, highlighting the development prospect of slurry pump and its commercial applications were elaborated, when the trend of deep-sea mining was discussed.
2014 Vol. 32 (4): 319-326 [Abstract] ( 1504 ) [HTML 1KB] [ PDF 1902KB] ( 2218 )
327 Influence of different lower edge shapes on surrounding flow field in shut-down process of ring gate
Li Luhui, Xiao Juliang, Mo Zhenwei, Wang Gang, Wang Guodong
To study the influence of lower edge shapes on the surrounding flow field of the ring gate in the shut-down process, the ring gate of Nansha Hydropower Station has been discussed for an example. There were two common lower edge shape models of the ring gate. Numerical simulation of three dimensional unsteady flow was conducted by using the fluent software with the RNG k-ε turbulence model. The simulation exerted the dynamic mesh and moving mesh focusing on studying the velocity field and the pressure field around the ring gate as well as the bottom pressure distribution under diffe-rent ring gate. By the contrastive analysis, the consequence that the ring gate with a small inclination lower edge has a better performance than with arc-shaped lower edge was got, in the aspects of cavita-tion corrosion, upsetting moment and hydraulic loss et al. However, the ring gate with arc-shaped lo-wer edge has a smaller fluctuation for overturning force and pull force. During the closing process, the bottom pressure distribution has a smaller variation which can prevent hairpin phenomenon effectively. The study will provide theoretical reference for designing and optimizing the shape of the ring gate edge and can be conducive to the stability of the ring gate operation. 
2014 Vol. 32 (4): 327-332 [Abstract] ( 1569 ) [HTML 1KB] [ PDF 3790KB] ( 1237 )
333 New method of investigation on 3D hydrodynamic model in curvilinear coordinates
Wu Weiguo, Shen Luyu, Xue Shifeng
A numerical method for solving three-dimensional hydrodynamic model in curvilinear coordinates was presented. High-order and high-resolution compact finite difference scheme and upwind compact finite difference scheme for nonlinear terms were used as spatial discretization,and the time integration was accomplished by 4th-order modified Runge-Kutta scheme. To verify the numerical me-thod, the same physical parameters of De Vriend's 180° curved channel test were used in the simulation. The results show that, the new numerical results are closer to the experimental data than the results calculated by using SIMPLEC. The maximum relative error between numerical and experimental average velocity results is less than 3%. It is proved that the numerical method presented is feasible and rational. To sum up, it is an efficient, feasible and rational way to numerically solve hydrodynamic problems, and can be used in many engineering computations of territorial waters as natural rivers, open channels and lakes with arbitrary complex boundaries. 
2014 Vol. 32 (4): 333-337 [Abstract] ( 1356 ) [HTML 1KB] [ PDF 1567KB] ( 1326 )
338 Effects of trace quantity irrigation on yield,dry matter portioning and water use efficiency of spherical fennel grown in greenhouse
Zhu Jun,, Jin Jishi, Yang Chunxiang
Trace quantity irrigation is a new irrigation technology based on soil capillary force principle and membrane filtering technology. A study was carried out to investigate the effects of trace quantity irrigation on crop yield, dry matter partitioning and water use efficiency of spherical fennel under greenhouse conditions. Drip irrigation was selected as control treatment. The results showed that yield and dry weight of edible part (bulb) and aboveground part (stem and leaf) were significantly higher under trace quantity irrigation than those under drip irrigation, while the total water consumption was significantly lower than that under the latter. Water use efficiency under trace quantity irrigation was 23 times as much as that under drip irrigation.
2014 Vol. 32 (4): 338-342 [Abstract] ( 1558 ) [HTML 1KB] [ PDF 1595KB] ( 1033 )
343 Review on research of farmland drainage technology
Wang Shaoli,, Xu Di,, Chen Haorui,, Han Songjun,, Jiao Pingjin,
The research achievements domestic and abroad in recent years were reviewed from three aspects: risk assessment of waterlogging disaster, technology as well as management of farmland drai-nage, and the prospects of future development of farmland drainage technology were described. The key research directions in the future was pointed out: the evolution laws of farmland waterlogging disaster under the changing environment should be studied, and the forecast and evaluation technique under artificial-natural complex conditions should be established; the integrated control standard of waterlogging disaster for satisfying the crop production and basic environmental protection demand should be investigated to promote the technical level and management model of conventional farmland drainage control, and the combined system of modern and conventional drainage technology should be discussed; the efficient utilization of farmland drainage resources should be paid attention, and the farmland drainage management model should be studied combining water-saving irrigation with controlled drainage, irrigation and drainage with pond purification, drainage water reuse for irrigation with waterlogging and drought control.
2014 Vol. 32 (4): 343-349 [Abstract] ( 1380 ) [HTML 1KB] [ PDF 1374KB] ( 1363 )
350 Effect of straw mulching on growth and yield of cotton under drip irrigation in arid area
Zhang Jinzhu,, Wang Zhenhua,, Hudan·Tumarebi
In order to explore the effect of straw mulching on growth characteristics and yield of drip irrigation of cotton in North Xinjiang, comparative trial in test-pit has been done from 2009 to 2012. Considering wheat straw as materials in the experiment, three treatments, surface coverage(LSM), 30 cm under the surface coverage(LM30)and no pit experiments(LUM), were carried out respectively. The results show that straw mulching has certain influence on the growth and yield of cotton under drip irrigation, especially in saline-alkali soil. Straw mulching has insignificant effect on drip irrigation cotton plant height, leaf area index and yield relatively in non-saline soil condition. The comprehensive regulation effect of surface coverage as well as the aspect of salt inhibition is better than that of LM30 especially in cotton growth period(flowering and boll-setting period). LM30 can create better conditions in seedling and cotton bud stage, but this effect is less pronounced after the blooming period. When the LSM is used, the highest yield of cotton can be obtained, which is 3.2%-17.9% higher than LUM and 3.1%-16.3% higher than LM30.
2014 Vol. 32 (4): 350-355 [Abstract] ( 1619 ) [HTML 1KB] [ PDF 1626KB] ( 1366 )
356 Comprehensive evaluation on farmland leveling methods based on TOPSIS model
Wei Zhanmin, Li Zeming, Li Jiabao
A comprehensive evaluation of the two common leveling methods(laser leveling and traditional leveling method), based on the TOPSIS model was conducted on various specifications of sample plots in Hetao Irrigation District of Inner Mongolia. Firstly, the selection of samples from 2011 to 2013 and the collection of data was done, and the assessment parameters were confirmed. Then, an evaluation index system was built on the basis of estimation and test of each parameter. Thus, the TOPSIS model was utilized to evaluate the assessment index system comprehensively. Finally, the optimal cases for each sample was reached, and the practical analysis in Hetao Irrigation District of Inner Mongolia was finished. Results indicate that the appropriate leveling method is the traditional one when the area of fields are below 1 100 m2. The laser leveling methodology is superior to the traditional method if the field area is bigger than 2 000 m2. Only small differences can be observed once the field area is between 1 100 and 2 000 m2. By the comprehensive consideration, the laser leveling method can be ge-nerally better than the traditional one. Currently, the border irrigation is main method for Hetao Irrigation District in Inner Mongolia, and the acreage of those borders are small and ranges from 1 000 to 1 330 m2, and in some local area the acreage is less than 670 m2. This will limit not only the largely popularization of laser land leveling technology, but also the development of local agricultural economy. 
2014 Vol. 32 (4): 356-362 [Abstract] ( 1549 ) [HTML 1KB] [ PDF 1467KB] ( 1215 )
363 Crop image recognition based on ComVI and double threshold OTSU algorithm
Gong Lixiong
A new recognition method of crop image with soil and other noise was proposed, which was used by combined vegetative indices(ComVI)and double threshold OTSU algorithm. The method has three stages of image processing according to unmasked and masked crops image characters. Firstly, the gray-scale image was adopted with combined vegetative indices, then the binaryzation and image segmentation were processed by way of double threshold OTSU adaptive method, and finally, post-treatment to the segmented binary images by morphology operation was also implemented. Therefore, crops and coil were recognized by superimposing the segmentation image in the three stages. Experimental results shows that it is a high performance algorithm which can overcome drawbacks of traditio-nal gray-scale image and threshold iterative method, and can effectively extract and recognize transitional edge image. The image recognition accuracy is more than 92.7%. Finally, crop image recognition system was designed to achieve the image recognition of the visualization and automation by Visual Basic 2010 and Matlab 2012 software.
2014 Vol. 32 (4): 363-368 [Abstract] ( 2141 ) [HTML 1KB] [ PDF 1794KB] ( 1173 )
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