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Journal of Drainage and Irrigation Machinery Engin
 
2022 Vol.40 Issue.10
Published 2022-10-25
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2022 Vol. 40 (10): 1- [Abstract] ( 78 ) [HTML 1KB] [ PDF 64978KB] ( 1077 )
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2022 Vol. 40 (10): 2- [Abstract] ( 17 ) [HTML 1KB] [ PDF 1187KB] ( 252 )
973 Effects of blade wrap angle on hydraulic performance and erosion characteristics of centrifugal pump
LIU Dong,HUANG Kai,NI Zijian,YANG Song*,YOU Baojian
Based on the CFD-DEM(computational fluid dynamics-discrete element method)coupling method, the solid-liquid two-phase flow in the centrifugal pump and the erosion of the flow parts were calculated. The average erosion rate of the impeller, the velocity distribution of the liquid phase, the movement of the particles, the number of contacts between the particles and the wall, and the contact force at different blade wrap angles were studied. The study shows that as the wrap angle increases, the head, efficiency and average erosion rate all increase first and then decrease. When the wrap angle is 110°, the contact force and the number of contacts between the particles and the wall surface are the largest, resulting in the most serious erosion. The position of severe erosion located at the junction of the middle of the suction surface and the shroud. When the wrap angle increases from 110° to 160°, the low-velocity area of the suction surface gradually decreases, resulting in a gradual decrease of low-velocity particles gathered in the middle of the suction surface, reducing the area where the suction surface is severely eroded.

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2022 Vol. 40 (10): 973-980 [Abstract] ( 24 ) [HTML 1KB] [ PDF 46612KB] ( 310 )
981 Influence of guide vane opening on water-ring flow characteristics of pump-turbine in synchronous condenser mode
LIU Dianhai,ZHU Baoshan,CHEN Shuai,CHEN Zhenmu*,ZHANG Fei
It is necessary to inject air into the runner passage to reduce the starting power, when pump turbine operates under the starting process in pump mode or under the synchronous condenser mode. In order to prevent the compressed air in the runner passage from leaking into the casing, it is necessary to form a certain thickness of water-ring in the vaneless space for sealing to reduce the air consumption. In order to investigate the water-ring characteristics of pump-turbine in synchronous condenser mode by different guide vane openings, the ANSYS CFX software was employed to conduct the unsteady state analysis with two-phase flow. The pump-turbine model was adopted to investigate the internal flow characteristics on the water-ring with three guide vane openings(full closed, 1% GVO, 2% GVO). The research shows that the thickness of the water-ring increases with decrease in guide vane opening, which results in increasing the resistance of the runner and the consumption of the shaft power. At the same time, the dominate frequency of pressure fluctuation in the vaneless space is the blade pass frequency and harmonics, which represents the phenomenon of rotor-stator interaction obviously. The research results can provide a reference for controlling water-ring of pump-turbine in the process of synchronous condenser mode and sump start-up mode.

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2022 Vol. 40 (10): 981-986 [Abstract] ( 33 ) [HTML 1KB] [ PDF 3600KB] ( 353 )
987 Numerical simulation on influence of helix angle on single screw pump leakage
WANG Yiran,CHEN Nan*,QING Hangxiao,YU Xiaodong
In order to explore the influence on the single screw pump leakage of different structure parameters, a geometric model of 1/2-line all-metal single screw pump was constructed as an example. Based on PumpLinx software for the transient numerical simulation, the reliability of results on CFD model was verified by the external characteristic test. And the flow variation law and flow field distribution of single screw pump with different total helix angles were studied. The results show that under the condition of constant unit helix angle, the time-average flow rate increases with the increase of the total helix angle and the unit pressure difference decreases. The minimum instantaneous flow rate decreases with the increase of the total helix angle. The value is basically consistent and close to the theoretical flow rate of 17.9 m3/h. The pressure on both sides of the oblique leakage gap changes with the engagement position of the stator and rotor, and the pressure difference at a specific position decreases with the increase of total helix angle. The maximum value of the transient leakage velocity at the monitoring point of a specific meshing zone decreases with the increase of total helix angle, and the minimum value is 4.3 m/s. Relevant research results have certain reference significance for leakage analysis and optimization design of single screw pump.

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2022 Vol. 40 (10): 987-992 [Abstract] ( 29 ) [HTML 1KB] [ PDF 2260KB] ( 337 )
993 Fault diagnosis of centrifugal pump anchor bolt loosening based on RBF neural network
SONG Liwei,ZHANG Yixun,CHEN Zeyu,ZHANG Yuhang,FAN Chuanhan,XIAO Xingxin,DONG Liang*
In order to accurately identify the loosening fault of the anchor bolt of horizontal centrifugal pump, a diagnostic platform of horizontal centrifugal pump unit was built, and eddy current sensor was used to monitor the rotor displacement of centrifugal pump. The acquired rotor displacement signals were decomposed into multiple intrinsic mode functions(IMF)by empirical mode decomposition(EMD), and the fault sensitive component was obtained by analyzing the IMF spectrum characteris-tics, correlation coefficient and energy ratio of each layer. Finally, the radial basis function(RBF)neural network was used to identify and predict the loosening fault of the centrifugal pump. The results show that the EMD method can effectively extract the centrifugal pump loosening fault features, and the IMF5—IMF8 layer can be used as the fault feature components. An accuracy of 95% can be reached by inputting the correlation coefficient and energy ratio of IMF5-IMF8 layers into the RBF neural network as fault features for recognition.

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2022 Vol. 40 (10): 993-998 [Abstract] ( 25 ) [HTML 1KB] [ PDF 4034KB] ( 314 )
999 Study on the optimal water distribution model of canal system in Hetao irrigation district
HAN Yu*,SHAO Mengxuan,LI Tongshu,GUO Shanshan,SUN ZhiPeng,ZHANG Mingwu
Optimizing the water distribution process of the canal system is an important measure to alleviate the pressure of water resources in the irrigation area and achieve efficient water saving in agriculture. A canal system optimization model is established by taking the general main canal and main canal system in Hetao irrigation district as the research object and taking the steady flow transition and the minimum water loss as two optimization objectives. The model is solved by backtracking search algorithm(BSA), multi-objective particle swarm optimization(MOPSO)and vector evaluation genetic algorithm(VEGA). The results show that the water distribution time of BSA, MOPSO and VEGA is 30.96, 11.65 and 29.96 d respectively, and the skewness coefficients of the valve opening time points are -0.048, 0.068 and 0.566, which means that BSA and MOPSO can guarantee the stability of irrigation water in the canal transportation. Considering the change of the water level at the head of the canal, BSA and MOPSO are applicable to the situation where the water intake of the canal head is less and sufficient respectively. Considering the concentration of water distribution time and the geographical distribution of main canals, BSA and MOPSO are conducive to the implementation of zoning management measures.

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2022 Vol. 40 (10): 999-1006 [Abstract] ( 27 ) [HTML 1KB] [ PDF 1642KB] ( 333 )
1007 Feature extraction of cavitation acoustic emission signal of hydraulic turbine based on optimized VMD combined noise reduction and LMD
LIU Zhong*,PAN Yihua,ZOU Shuyun,CHEN Xingyu,LI Zhipeng
Aiming at the problem that noise exists in the acoustic emission signal of hydraulic turbine cavitation, which affects the effective extraction of signal features, a feature extraction method of acoustic emission signal of hydraulic turbine cavitation based on the combination of noise reduction and Local Mean Decomposition(LMD)of optimized Variational Modal Decomposition(VMD)and Birge-Massart strategy was proposed. In view of the significant influence of penalty factor and decomposition mode number on the decomposition results in VMD algorithm, the minimum value of dispersion entropy difference correlation coefficient was proposed as the objective function, and Harris Hawk Optimization(HHO)was used to optimize the parameters of VMD. The signal was decomposed with the VMD of the optimal parameters, and a series of Intrinsic Mode Functions(IMF)were obtained. The correlation coefficient of each IMF is calculated, the IMF with correlation coefficient less than 0.1 were eliminated, the IMF greater than 0.5 were retained, which were the IMF between 0.1 and 0.5 were denoised using the wavelet BM criterion, and reconstructed with the retained components. The reconstructed signal was processed by LMD, which were the energy of the decomposed Product Function(PF)component was extracted as the signal feature. The experimental results show that there is a negative correlation between PF component energy and cavitation coefficient after optimized VMD combined noise reduction treatment and LMD treatment, which verifies the feasibility of the proposed method for cavitation state identification of hydraulic turbines.

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2022 Vol. 40 (10): 1007-1013 [Abstract] ( 16 ) [HTML 1KB] [ PDF 2117KB] ( 348 )
1014 Markov grey residual model for predicting strength of cement Pisha sandstone
LIU Xin,SHEN Xiangdong*,JING Yu,REN Jie,LYV Xin,GENG Kaiqiang
In order to study the accuracy and applicability of Markov-grey residual GM(1,1)model in predicting compressive strength of cement pisha sandstone, after a series of processings of compressive strength data, the grey GM(1,1)model and grey residual GM(1,1)model were established. Then the Markov-grey residual GM(1,1)model was constructed based on the Markov process, and the compressive strength of cement-cured pasha sandstone was estimated by this model. The results show that the test accuracy of the grey residual GM(1, 1)model is greatly improved and all the test indexes basically reach level 1, which is obviously better than that of the grey GM(1, 1)model. The Markov process is convenient to determine the positive and negative signs of residual correction, and then the compressive strength of cement solidified Pisha sandstone with different cement contents at 90 days was predicted by the Markov- grey residual GM(1,1)model. The relative error is reduced from 1.77%~4.01% to 0.60%~2.36%, and the average relative error is reduced from 2.63% to 1.25%. The prediction accuracy of the model is improved obviously. This study can provide a simple and reliable new method and way for predicting the compressive strength of cement-cured Pisha sandstone and other cement-based engineering materials.

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2022 Vol. 40 (10): 1014-1019 [Abstract] ( 15 ) [HTML 1KB] [ PDF 1855KB] ( 233 )
1020 Analysis on reasonable opening angle of double-stage flap valve in pumping station
LU Weigang,ZHOU Bingnan,CHEN Hua,XIA Hui,XU Bo*
To explore reasonable opening angles of double-stage flag valve, the double-stage flap valve of Jiangxi Ehu pumping station was taken as the research object, and the operating angle of the double-stage flap valve was calculated by theoretical formula to determine the test scheme. The hydraulic loss of the flap valve and the flow state of the water behind the flap valve under different flow conditions and different opening angles of the flap valve were studied, and an optimal opening angle range of the double-stage flap valve was obtained. The research results show that the hydraulic loss is small and its size hardly changes with the increase of flow rate when the opening of the upper section of the double-stage flap valve reaches 46.00° and the opening of the lower section door reaches 64.00°. The efficiency decrease caused by the hydraulic loss of the flap valve has been reduced to about 3%, and the flow pattern has been able to develop completely in the culvert. Moreover, with the increase of the opening angle, the impact of the flap valve on the pump device performance and the overall project operation is gradually weakening. Through analysis and research, it is concluded that the optimal opening range of the upper flap valve and the lower flap valve in the double-stage flap valve of Ehu pumping station is 46.00° to 53.00° and 64.00° to 70.00°, respectively. It is consistent with the opening angle of the double-stage flap valve under the operating condition, which can provide reference for the application of double-stage flap valve in the pumping station. By analyzing and comparing from multiple angles, it is concluded that the research method of reasonable opening angle of double-stage flap valve is obtained, which is highly feasible and worthy of popularizing and applying in the research of reasonable opening angle of other types of flap valve.

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2022 Vol. 40 (10): 1020-1026 [Abstract] ( 12 ) [HTML 1KB] [ PDF 4317KB] ( 385 )
1027 Numerical simulation for the windproof effect of herringbone photovoltaic array
ZHAO Wenju*,LIU Guiyuan,HU Junhong,HU Jiazhen
Drawing on the ideas of goose array theory, a herringbone photovoltaic array was designed. In order to reveal its windproof effect, the wind load resistance and wind reduction of the case that the installation inclination, height, array angle and spacing were 30°, 0.20 m, 30° and 2 m respectively, were investigated by using the SST k-ω turbulence model and unsteady Reynolds-Average Navier-Stokes(RANS)approach. The results show that at wind speeds of 10 m/s and 15 m/s, the first row of photovoltaic array is subject to the maximum wind pressure in the windward direction, the 2nd—5th exhaust pressure is significantly less than the first row and decreases row by row, and the array has a goose array effect. The monitoring point |P| is divided into different wind pressure areas at intervals of 20 Pa, and it is found that a local reinforcement method can be adopted to improve the overall wind resistance of the photovoltaic array. In the vertical direction, the incoming flow forms a near-pyramid-shaped wind speed attenuation area behind the array, and the wind speed distribution shows medium variability. In the process of increasing the height above ground from 0.20 m to 0.70 m, due to the diversion effect of the array, the residual coefficient of the average wind speed in the calculation domain gradually increases, and the coefficient of variation gradually decreases, so that the wind protection effect of the photovoltaic array in the calculation domain weakens as the elevation increases. It provides theoretical guidance for the layout of Gobi herringbone photovoltaic arrays and agricultural development.

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2022 Vol. 40 (10): 1027-1032 [Abstract] ( 20 ) [HTML 1KB] [ PDF 3082KB] ( 288 )
1033 Flow field characteristics of wet curtain and fan in multi-span greenhouse
GAO Zhenjun,LI Wengyang,DING Xiaoming*,LI Wei,Nyam-Osor Batkhuu
In order to understand the changes in the temperature field and velocity field of the large-scale multi-span solar greenhouse in southern China under the conditions of curtain-fan ventilation, and to explore the ventilation and cooling performance in the greenhouse under this ventilation method, taking the large-scale multi-span solar greenhouse in the Demonstration Base of Guangzhou Agricultural Technology Extension Station as the research object, the steady-state and transient calculations were carried out. The multi-span solar greenhouse established a three-dimensional steady-state and transient calculation model for the research object. The calculation results of the steady-state model are compared with the data obtained from the monitoring points in the greenhouse to verify the reliability of the calculation model, and the transient calculation of the wet curtain-fan ventilation conditions is carried out, and the intuitive temperature and speed distribution and change rules in the greenhouse are obtained. The results show that after the wet curtain-fan system is started, the wind speed on the side of the wet curtain can reach 1.6 m/s in the ventilation process, it gradually develops into a high-speed airflow field from the entrance of the wet curtain to the outlet of the ventilator, and the airflow speed is finally stable at 0.8 m/s. The temperature field in the greenhouse shows the characteristics of gradient cooling from the side of the wet curtain to the side of the fan, and it is accompanied by a slight global cooling of the greenhouse. After doubling the flow rate, the turbulence during the development of the velocity field increases, and the cooling speed increases significantly. The results will provide a reference for the normal operation of the multi-span solar greenhouse in South China and the precise control of the microclimate environment in the greenhouse.

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2022 Vol. 40 (10): 1033-1039 [Abstract] ( 18 ) [HTML 1KB] [ PDF 23610KB] ( 230 )
1040 Effects of irrigation timing and water temperature on cotton growth and yield under mulched drip irrigation
WANG Zhenhua*,WU Xiaodi,WANG Tianyu,ZONG Rui,WANG Dongwang,CHEN Rui,
In order to explore the effects of different irrigation timing and water temperature on the physiological characteristics and yield of cotton under mulched drip irrigation, four irrigation water temperature levels were set as 15(normal irrigation water temperature), 20, 25, and 30 ℃, and two irrigation timing levels were daytime and nighttime(denoted as DW and NW, respectively)for a complete combined design, with a total of eight treatments. The results showed that warming irrigation advanced the growth process of cotton, promoted the growth of plant height, stem diameter and leaf area of cotton, and was conducive to the photosynthesis of cotton, and the effect of warming irrigation at night was more significant. Warming irrigation significantly increased seed cotton yield by 2.95%Symbolm@@14.13%, and nighttime irrigation increased cotton yield by 3.34% compared with daytime irrigation. Based on regression analysis, it was determined that the best irrigation time to increase cotton yield was at night, the best irrigation water temperature was 26.38 ℃, and the corresponding yield was 7 482.96 kg/hm2. The results could provide theoretical basis and technical reference for the implementation of warming irrigation technology for drip irrigation cotton under film in northern Xinjiang.

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2022 Vol. 40 (10): 1040-1047 [Abstract] ( 22 ) [HTML 1KB] [ PDF 2199KB] ( 292 )
1048 Process of soil moisture infiltration and model analysis of gravel-mulched land with different planting years
WANG Youqi*,RUAN Xiaohan,BAI Yiru,GAO Xiaolong,
In order to explore the influence of gravel-mulched land with different planting years on soil water infiltration, the indoor vertical one-dimensional soil column infiltration test was used to analyze the gravel-mulched land with different planting years(2, 5, 10, 20, 30 and 40 a). Soil infiltration rate, cumulative infiltration volume and wetting front migration law were transformed into 4 infiltration models to fit the soil moisture infiltration process of gravel-mulched soil and evaluate its applicability, through a one-dimensional algebraic model and related parameters. The prediction results showed that with the increase in sowing years, the cumulative soil infiltration amount, infiltration amount and the distance of the wet front movement were all significantly reduced. When the infiltration time was 300 min, compared with 2 years, the cumulative infiltration of 5, 10, 20, 30 and 40 a decreased by 27.01%, 43.32%, 53.22%, 54.79% and 54.68%, respectively and the distance of wet front migration decreased by 24.84%, 38.38%, 48.56%, 52.67% and 54.00%. The R2 sequence of the four infiltration models was: Horton model> common experienced model> Kostiakov model> Philip model. The MAE between the soil profile scale values of different planting years fitted by the dimensional algebra model and the measured values were all between 0.48% and 2.09%, the RMSE were between 0.52% and 2.13%, D were all greater than 0.782, and t, test P values were greater than 0.05 which showed that it can better fit the water distribution of gravel-mulched land with different planting years. The longer the planting period of gravel-mulched land, the worse the water infiltration capacity and the lower the soil profile moisture content. It was recommended that the sustainable development of gravel-mulched land should be realized through measures such as strengthening management and fallow.

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2022 Vol. 40 (10): 1048-1055 [Abstract] ( 28 ) [HTML 1KB] [ PDF 1635KB] ( 355 )
1056 Practical path of promoting agricultural modernization by modernization of agricultural science and technology
JIN Lifu,WU Zhendong*
In order to accelerate the process of China′s agricultural modernization, based on the practical path of agricultural science and technology modernization, the connotation of agricultural modernization and agricultural science and technology modernization was firstly explained. On the basis of a profound analysis of the internal logic of agricultural modernization and agricultural science and technology modernization, the practical significance of agricultural science and technology modernization to promote agricultural modernization was then discussed. Further more, the practical problems existing in the modernization of agricultural science and technology in the process of agricultural modernization was summarized. It was found that the backwardness of science and technology policies, the low effectiveness of science and technology promotion, and the insufficient construction of science and technology talents seriously restrict the development of agricultural modernization in the new stage. The results show that the realization of agricultural science and technology modernization needs continuous efforts in science and technology policies, promotion systems, scientific and technological talents, and smart agriculture. This study will provide theoretical support and practical guidance for building a complete agricultural science and technology modernization system and promoting the steady realization of agricultural modernization.

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2022 Vol. 40 (10): 1056-1064 [Abstract] ( 14 ) [HTML 1KB] [ PDF 1453KB] ( 290 )
1065 Analysis of influencing factors on atomization characteristics of fan nozzle
JIANG Xiaoping*,WANG Shuai,CHEN Jianhua,JI Jing,ZHU Chaojia,ZHU Xingye
In order to solve the problem of atomization characteristics of fan nozzles, the coupling algorithm of Eulerian-Lagrangian continuous phase and discrete phase was adopted based on Taylor Analogy Breakup(TAB)model in Ansys Fluent. The fan-shaped nozzle droplet crushing, atomization formation and unsteady numerical simulation of gas-liquid two-phase flow field were realized. The research on the influence of the injection pressure and the two parameters on the fan nozzle spray height droplet velocity and droplet diameter, the discrete phase model(DPM)mass concentration, droplet flux(N)of atomization characteristic parameters were completed. Through the test bench to test the laser granulometer droplet sauter mean diameter(DSM), the simulation results were compared. The results show that with the increase of injection pressure and droplet velocity, the average residence time of droplet in the computational domain is shorter, and the number of droplet in the computational domain is less. Droplet sauter mean diameter(DSM), droplet size median diameter(DVM), number of median diameter(DNM)with the increase of injection pressure are more and more small. After the injection pressure is 0.3 MPa, droplet DSM decreases to larger diameter, which is beneficial to improve the quality in the actual operation of atomization. Under windy conditions, risk of escaping droplets will also increases. Spray height has little effect on droplet DSM. The DPM mass concentration and spray coverage area under different injection pressures are not affected by the injection pressure. Since the change of N is in inverse proportion to the cubic DSM of droplet and the coverage area A, the quantity flux of droplet gradually increases with the increase of injection pressure. The mass concentration of DPM decreases gradually with the increase of spray height, and the spray coverage area increases gra-dually with the increase of spray height. As the DSM of droplet changes with the spray height, the droplet number flux decreases with the increase of spray height. The variation trend of DSM obtained by test and simulation calculation under different spray pressures and different spray heights is consistent, and the error of the whole process is less than 10%.

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2022 Vol. 40 (10): 1065-1071 [Abstract] ( 23 ) [HTML 1KB] [ PDF 4583KB] ( 391 )
1072 Challenges and opportunities for development of sprinkler irrigation machine in China
TANG Lingdi,YUAN Shouqi*,LIU Junping,QIU Zhipeng,MA Jun,SUN Xiangyang,ZHOU Chuanguo,GAO Zhijun
Based on the water conservancy statistics, the application distribution of water-saving irrigation in China in the past 10 years was analyzed, it′s obvious regional characteristics was found, sprinkler irrigation is mainly used in the northeast, micro irrigation is mainly used in the northwest, low-pressure pipe irrigation is mainly used in North China, and canal irrigation are mainly used in East China. Water-saving irrigation still has 50% development space, and the proportion of sprinkler irrigation technology is still low compared with European and American countries. The development history, research progress and development trend of sprinkler irrigation in China were reviewed. The development opportunities of sprinkler irrigation machines in China under the challenge of resource and environment constraints was analyzed from the four aspects of national policy guidance, intelligent agriculture development, agricultural planting structure change and saline-alkali land transformation. The advantages and irreplaceable role of sprinkler irrigation are clarified. In addition, with the steady progress of high standard farmland construction and large-scale agricultural management in China, the perfor-mance and function of sprinkler irrigation machines are continuously enhanced, which gradually turns the limitations of previous sprinkler irrigation into development advantages. Finally, the future development prospects of sprinkler irrigation machines in China are prospected from the aspects of making up for the shortcomings of the whole process mechanization of agriculture, the new mode of integrated operation of water, fertilizer and medicine, and unmanned intelligence.

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2022 Vol. 40 (10): 1072-1080 [Abstract] ( 23 ) [HTML 1KB] [ PDF 10613KB] ( 328 )
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