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Journal of Drainage and Irrigation Machinery Engin
2020 Vol.38 Issue.7
Published 2020-07-25

2020 Vol. 38 (7): 1- [Abstract] ( 0 ) [HTML 1KB] [ PDF 1542KB] ( 14 )
2020 Vol. 38 (7): 2- [Abstract] ( 0 ) [HTML 1KB] [ PDF 898KB] ( 15 )
2020 Vol. 38 (7): 649-657 [Abstract] ( 1 ) [HTML 1KB] [ PDF 3625KB] ( 28 )
658 Numerical simulation of submerged impinging water jet at different impact angles
CHEN Xinxin,WANG Chuan*,SHI Weidong,ZHANG Yingchong
Numerical simulations of fully developed submerged impinging water jet were carried out by using the commercial CFD software ANSYS Fluent with the Wray-Agarwal(W-A)turbulence model to investigate the influence of impact angle on the jet flow field.The structure and velocity distribution of the flow field with a constant jet-to-plane distance H/D=3 and different impact angles(15°≤θ≤90°)were studied. A comparison was made between the numerical results and the experimental data obtained with PIV, then the reliability of the W-A turbulence model was validated, furthermore, the influence of impinging angle on the computational results was discussed. The results show that the impinging jet axial velocity V/Vb remains unchanged basically in the potential core region, decreases in the transition region, and drops off at an acceleration in the impact zone. The jet flow changes direction and diffuses along the wall in the near wall region.The jet flow field is largely dependent on the impact angle θ. With increasing θ, the horizontal diffusion of the jet is deteriorated and the thickness is thinned.At θ=90°, the stagnation point and the point of transition in the flow direction coincid with the impact origin. The stagnation point gradually moves away from the impact origin with decreasing θ, and it disappears at θ<30°.
2020 Vol. 38 (7): 658-662 [Abstract] ( 1 ) [HTML 1KB] [ PDF 2012KB] ( 21 )
663 Test on pressure fluctuation in pump end of axial pistonenergy recovery integrated machine under multiple operational condition
LIU Zhuxun,ZHANG Desheng*,CAI Jiaxi
In order to study the pressure fluctuation characteristics in pump end of axial piston energy recovery integrated machine for seawater desalination at different rotational speeds and outlet pressures, the pressure sensors were installed at the inlet and outlet of the pump end, respectively, and the pressure fluctuation tests were performed at rotational speeds of 800 r/min, 1 000 r/min, 1 200 r/min, 1 450 r/min(rated speed),1 600 r/min and outlet pressures of 4.5 MPa, 5.5 MPa, 6.5 MPa, and 7.5 MPa. In time domain, the experimental results show that the fundamental wave in the pressure fluctuation curves is in a triangular shape, and its amplitude is attenuated with increasing rotational speed, but the amplitude of harmonics gradually increases. Even though the inlet pressure fluctuation curves are in a triangular shape at low rotational speeds, the waveform changes irregularly as the rotational speed increases. In frequency domain, the results show that the shaft rotational frequency is the primary frequency influencing the pressure fluctuation at the pump end outlet at low speeds. With increasing rotational speed, however, the piston multiple frequency becomes more dominant at high rotational speeds, especially harmonics appear at 3Z(Z—number of pistons)multiple frequency of the shaft rotational frequency. As the outlet pressure of the pump rises continuously, the amplitude of the outlet pressure fluctuation at the shaft frequency and the piston frequency increases steadily, but the pressure fluctuation rate(dimensionless amplitude)is constant basically. Further the frequency distribution is more concentrated. The inlet pressure fluctuation rate is decreased at the shaft frequency and rises at the piston multiple frequency.
2020 Vol. 38 (7): 663-669 [Abstract] ( 2 ) [HTML 1KB] [ PDF 9160KB] ( 28 )
670 Energy transfer characteristics of fluid in impeller of helical axial-flow multiphase pump
SHI Guangtai,LUO Kun*,LIU Zongku,WANG Zhiwen
Numerical simulations were conducted in a helical axial-flow multiphase pump under water single-phase and air-water two-phase flow conditions to quantitatively analyze energy transfer characteristics of the fluids in the impeller, respectively. By demonstrating the energy transfer characteristics in the impeller, the relationships of flow rate and inlet air volume fraction with the work done in diffe-rent regions of the impeller were revealed. The results show that the impeller mechanical energy is mainly transferred to the fluids in the middle region of the impeller, and the most energy transferred is in static pressure. Further, the impeller capacity of doing work firstly increases and then decreases from the impeller inlet to the outlet. Under water single-phase flow conditions, with increasing flow rate the impeller capacity of doing work is gradually enhanced in forepart of the impeller but weakened in rear part. Under air-water two-phase flow conditions, with increasing inlet air volume fraction, the impeller capacity of doing work is degraded gradually, especially for forepart of the impeller, and the capacity in rear part is less affected. These results can provide a reference for the optimal design of flow components of the helical axial-flow multiphase pump.
2020 Vol. 38 (7): 670-676 [Abstract] ( 3 ) [HTML 1KB] [ PDF 2793KB] ( 26 )
677 Effects of number of blades on performance of waterwheel based on volume of fluid model
ZHAO Mengshang,ZHENG Yuan*,YANG Chunxia,ZANG Wei
Unsteady fluid flows around waterwheels in an open channel were simulated numerically in Fluent based on volume of fluid(VOF)model to study the waterwheel-based power generation device by utilizing micro-head in this paper. The SST k-ω two-equation turbulence model and sliding mesh were adopted to carry out unsteady flow simulations when the waterwheels were with different numbers of blades and at different rotational speeds. The results indicate that the 3-bladed waterwheel has the best optimal efficiency and the widest optimal efficiency zone. Since the local turbulent viscosity in the upstream of the 3-bladed waterwheel is larger, the range of influence generated by the waterwheel in the channel is smaller. For the 8-bladed waterwheel, however, the average turbulent viscosity in the upstream is fair, the range of the influence is larger. Under the same working condition, adding more blades can intensify the waterwheel blockage effect to the stream and elevate the average water level difference between upstream and downstream significantly, but suppress the fluctuation of water level difference. An increased average water level difference will reduce the waterwheel power-output, and the fluctuation of water level difference can affect adversely the operational stability of the waterwheel rotator system. Under the same working condition, increasing number of blades can suppress the fluc-tuation of torque but reduce the power-output. Torque fluctuation is due to the action of imbalanced moments experienced by the waterwheel in operation, which may result in severe vibration of the waterwheel structure and fatigue damage to the blades.
2020 Vol. 38 (7): 677-682 [Abstract] ( 1 ) [HTML 1KB] [ PDF 3609KB] ( 30 )
683 Numerical simulation of hydraulic characteristics of plate-column compound flow meter with U-shaped channel
LI Yongye,GAO Yuan,SUN Xihuan*,ZHANG Xuelan,LU Yifan,JIA Xiaomeng,ZHANG Chunjin
In order to develop water-saving agriculture, promote efficient use of water in irrigated areas and allocate rationally water resources, a portable, accurate and movable flow meter with U-shaped channel, i.e. plate-column compound flow meter was innovated. Based on Flow-3D software, the hydraulic characteristics of the plate-column compound flow meter were numerically simulated with the RNG k-ε turbulence model, and the simulated results were validated with the experimental data. The results showed that the transverse, vertical velocity distributions and the relationship between the mea-sured flow rate and the rotational angle of the measuring device were consistent with the experimental observation with the maximum relative error less than 5.4%. The transverse velocity of water in channel free surface was increased first from the center of the channel and then decreased towards the channel wall. The vertical velocity in the symmetrical plane upstream was increased steadily from the bottom of the channel to the free surface, while the velocity downstream was increased first and then decreased from the bottom of the channel to the free surface, i.e. the maximum vertical velocity was located at somewhere underneath the free surface. The maximum influence range of the plate-column compound flow meter in the channel was in the flow field extended from the meter to 0.35 m upstream and 0.94 m downstream.
2020 Vol. 38 (7): 683-690 [Abstract] ( 1 ) [HTML 1KB] [ PDF 3932KB] ( 20 )
691 Influence of cold-temperature stagnation phenomenon induced by reservoir impoundment on downstream water temperature in spawning period of four major Chinese carps
MAO Jingqiao*,HUI Erqing
Based on the long-term water body temperature and meteorological data observed at a few key hydrological stations located upstream and downstream of Three Gorges Dam, the monthly average and five-year average water body temperatures were analyzed. The variation characteristics of water body temperature between Three Gorges Dam and Gezhou Dam as well as downstream of Gezhou Dam before and after the impoundment of Three Gorges Reservoir were clarified during the spawning period of four major Chinese carps. By generalizing the factors influencing the water body temperature diffe-rences before and after the impoundment, the temperature differences and the contribution of stagnation effect are quantified. The results show that the water body temperature changs greatly in April and May at Yichang Station after the impoundment. During the spawning period of carps from May and June, the monthly average water temperature is decreased by 1.40 and 0.49 ℃, respectively. The water temperature at Yichang station is decreased by 1.26, 1.71, 0.79, and 0.08 ℃ from March to June caused by the impoundment and a cold-temperature stagnation phenomenon is observed. However, the average monthly water temperature during this period at that station is still within the most suita-ble water temperature range for carps to spawn. The effect of the impoundment of Three Gorges Dam on water body temperature between Three Gorges Dam and Gezhou Dam as well as downstream of Gezhou Dam for the spawning sites of the carps is in a controllable range, which provides a manageable space for performing subsequent continuous ecological operation in reproduction of the carps.
2020 Vol. 38 (7): 691-696 [Abstract] ( 1 ) [HTML 1KB] [ PDF 1704KB] ( 22 )
697 Numerical simulation of flow and heat transfer characteristics in helical pipe
FENG Lulu,XU Rangshu*,FENG Jianyu
Aiming at fluid flow and heat transfer characteristics in helical pipes, an experimental model of helical pipe was selected as the study object. The flow and heat transfer of water in the pipe was numerically simulated by using Fluent, based on the realizable k-ε turbulence model and thin-wall thermal resistance model along with first kind thermal boundary condition. The velocity and temperature fields in the pipe were obtained at different water flow rates. In addition, the correctness of the numerical simulation method was validated by comparison with the experimental results. With increase of Reynolds number, the core of Dean vortex in the secondary flow in the pipe expands to the wall of the pipe. The comprehensive heat transfer properties in the pipe are the best in a small curvature ratio and at Reynolds number ranged in 2 280-6 000. The correlations of convective heat transfer and pressure drop were established by using multilinear regression model based on the simulated data. It can provide a certain reference for design and optimization of helical-coiled heat exchangers.
2020 Vol. 38 (7): 697-701 [Abstract] ( 2 ) [HTML 1KB] [ PDF 3747KB] ( 30 )
702 Analysis on wake deviation and turbulence characteristics of horizontal-axis wind turbine under yawed condition
GUO Maofeng,ZHANG Liru,*,LI Deyin,WANG Xueli,NIU Jiajia
Numerical simulations combined with theoretical analysis were used to analyze the wake of a 300 W horizontal-axis wind turbine with S-shaped airfoil under different wind speeds and yaw angles to explore variation characteristics of the wake. At first, the relationship between yaw angle and wind turbine output power was derived; then the deviation of the wake center and the variation of turbulence intensity in the wake were analyzed at different yaw angles. The results show that the pressure difference across the airfoil surfaces decreases with increasing yaw angle. The positive and negative pressure peak on the blade surfaces occurs once at every 120° azimuth angle. The critical interval of adverse yaw angle, which can cause obvious loss of wind turbine output power, is 10°-15°. The deviation degree of wake velocity center towards the negative direction of the X-axis is intensified with increasing yaw angle when the axial length is less than 1D. As the axial length being longer than 1D, the deviation degree increasing when the yaw angle is smaller than 15°, and decreases when the angle is greater than 15°. As the yaw angle increases, the maximum turbulence intensity in the wake is increased, and the wake turbulence intensity is restored quickly, thus the wake is shortened. The turbulence intensity distribution on both sides of the wake is asymmetrical and shows different variation patterns with yaw angle, resulting in the wind turbine wake having a more complicated turbulence environment.
2020 Vol. 38 (7): 702-707 [Abstract] ( 1 ) [HTML 1KB] [ PDF 2097KB] ( 21 )
708 Experimental study on suitable irrigation quota for emergence of maize under subsurface drip irrigation
WANG Ronglian,MO Yan,WANG Jiandong*,REN Zhihong,YU Jian,SHI Jigang
The effects of capillary operational parameters(dripper flow, buried depth)and irrigation quota on the wetting radius of subsurface drip irrigation for three typical soils in the Inner Mongolia autonomous region were experimented by using soil box to explore solutions to the problem of difficult emergence of maize under subsurface drip irrigation. Combined with the sowing depth of maize seeds and the distances of water moving upward and downward as well as the soil water content around the seeds, a proper irrigation quota for the maize was studied to improve the emergence rate and guide actual production. The results show that the irrigation quota and soil type have statistics significance on the wetting radius(P<0.05), but the dripper flow and buried depth have not. In the clay soil, the irrigation quota of 37.5-52.5 mm can basically meet the requirement of maize emergence when the capillary is buried at a depth in 25-35 cm. In the loam soil, the irrigation quota of about 37.5 mm can basically meet the requirement of 25-30 cm capillary depth, while the irrigation quota of about 52.5 mm can essentially meet the requirement of 30-35 cm capillary depth. In the sandy loam soil, the irrigation quota of about 22.5-37.5 mm can basically meet the requirement of 25 cm capillary depth, and the irrigation quota of about 52.5 mm can basically meet the requirement of 25-35 cm depth.
2020 Vol. 38 (7): 708-712 [Abstract] ( 1 ) [HTML 1KB] [ PDF 1502KB] ( 22 )
713 Effects of arrangement of surge-root irrigation emitters on growth, yield and water use efficiency of apple trees
LI Zhongjie,FEI Liangjun*,HAO Kun,LIU Teng,CHEN Nanshu,ZHANG Quanju,HUANG Deliang
Six-year old apple trees were selected for field experiment. The objective of this study is to obtain the reasonable arrangement of surge-root irrigation emitters in apple orchards. There are three factors: the buried depth H(25, 40, 55 cm), the horizontal distance L(30, 40, 60 cm)between the emitters and the trunk of the experimental tree, and the number of the irrigation emitters N(1, 2, 4). The effect of the arrangement of surge-root irrigation emitters on the growth, yield and water use efficiency(IWUE)of apple trees were studied in Northern Shaanxi where the irrigation quota takes 60%-75% of the field water capacity. The results showed that the arrangement of emitters for surge-root irrigation had a significant effect on apple tree yield and IWUE, especially, the yield and IWUE reached 28,388.17 kg/hm2 and 16.83 kg/m3 in treatment T3, respectively. At the same L and N levels(T1, T2, and T3), the yield and IWUE in treatment T3 were the highest, and the yields in treatments T1 and T2 were decreased by 26.22% and 31.48%, while IWUE is reduced by 14.02% and 18.12% compared with T3, respectively. At the same H and N levels(T3, T4, and T5), the yield and IWUE of apple trees were decreased with increasing L level. Especially, when L was 30 cm(T3), the yield and IWUE were the highest. The same L and H levels(T3, T6, and T7)could promote the growth of apple trees when N was 2(T3). Compared with treatment T3, it was found that the increment of new shoots was decreased by 8.07%-18.71%, and the fruit diameter was decreased by 5.41%-9.11%. Therefore, two emitters should be arranged symmetrically on both sides of an apple tree, each was buried at a 40 cm depth and 30 cm away from the trunk of the tree to effectively improve the yield and IWUE of the apple tree in mountainous areas in Northern Shaanxi.
2020 Vol. 38 (7): 713-719 [Abstract] ( 1 ) [HTML 1KB] [ PDF 1750KB] ( 26 )
720 Entropy weight TOPSIS model-based evaluation of rice irrigation and drainage modes at different nitrogen application levels
WANG Yu,YU Shuang′en*,DING Jihui,LI Qianqian,ZHANG Mengting,LIU Zixin,CHEN Kaiwen
Different rice irrigation and drainage modes were set up at three nitrogen application levels by taking farmland water level as control index. The yield and yield components of rice under these modes were studied. TOPSIS model based on entropy weight method was used to evaluate these irrigation and drainage modes to screen a rice irrigation and drainage mode that can achieve three goals such as high efficiency, water saving and pollution control. The results showed the alternate stress of drought and waterlogging at tillering stage had the most obviously inhibitory effect on the yield and pollution control index of rice but affected a little on water saving index. Under the alternate stress of drought and waterlogging, a low nitrogen fertilizer application level had an obviously inhibitory effect on rice growth and development. There was no significant increase in rice yield at a high nitrogen fertilizer application level. The leaching capacity of nitrogen at a high nitrogen fertilizer application level was larger than that at a low nitrogen fertilizer application level. The good-fitness of the controlled irrigation and drainage mode at a 300 kg/hm2 nitrogen fertilizer application level was 0.694 5 based on TOPSIS model. The alternation stress of drought and flood at tillering stage not only has the greatest adverse effect on rice growth and development of, but also has the worst effect on pollution control and emission reduction. Through model evaluation the optimal irrigation and drainage scheme is the controlled irrigation and drainage mode with the nitrogen application level of 300 kg/hm2.
2020 Vol. 38 (7): 720-725 [Abstract] ( 2 ) [HTML 1KB] [ PDF 1833KB] ( 27 )
726 Experiments on drainage rule and soil desalination effect under mulched subsurface pipe drainage
SHI Peijun,LIU Hongguang,*,HE Xinlin,LI Hong,LI Kaiming,
To investigate soil desalination effect and rules of subsurface pipe drainage in a saline-alkali field under drip irrigation mulched during irrigation process, a well-controlled experimental system was designed to simulate the soil desalination process and identify the effect of soil desalination under surface drip irrigation and subsurface pipe drainage conditions. Drainage and soil salinity distribution characteristics were analyzed by controlling irrigation time and quota and recording the water outflow time, drainage duration, drainage flow rate, drainage water mineralization level and soil salinity profile. The results show that the drainage velocity ultimately tends to be in the range of 1.5-3.5 L/h and the salinity of drainage varies in the ranges of 20-40 g/L after three irrigation leaching experiments. The desalination rates are as high as 85 % and 80.5 % in the 0-40 cm and 0-80 cm soil layers, respectively. The minimum salt rejection rates in the middle of two concealed pipes are 57.96%, 56.73%, and 69.29%, respectively, but the maximum salt rejection rates above the pipes are 71.73%, 73.34%, and 84.26%. The amount of salt discharged from the concealed pipes accounts for 28.9% of the total salt content in the 0-80 cm soil layer, and the rest of the salt is rinsed below the 80 cm soil layer.
2020 Vol. 38 (7): 726-730 [Abstract] ( 1 ) [HTML 1KB] [ PDF 1564KB] ( 24 )
731 Effect of mulched drip irrigation on water and heat transfer and crop water consumption in maize field
QI Mingdi,ZHANG Yanqun,WANG Weijie,WANG Chuanjuan,WU Zhongdong*,WANG Jiandong
Based on sufficient drip irrigation conditions, a quantitative analysis of differences of solar net radiation, soil heat flux, soil temperature and crop water consumption with film mulching and without film mulching was carried out in maize farmland in a northeastern typical region. Results show that film mulching makes the net radiation peak time lagged by about 1 hour on sunny days, and the soil heat flux can provide more energy for maize growth in film mulching on cloudy days. Throughout the whole growth period, the average net radiation flux received by the canopy is 133.25 W/m2 with film mulching compared to 135.42 W/m2 without film mulching. The available energy received by crops with film mulching is lower than that without film mulching. But in the middle and late growth stages, the net radiation flux in the former is increased by 2%. During the whole growth period, the average soil temperature and soil accumulated temperature in 0-80 cm soil layer with film mulching are increased by 1.13 ℃ and 149.68 ℃, respectively. In addition, the crop water consumption with film mulching is significantly lower than that without film mulching in the early and late growth stages, and the seasonal crop water consumption and crop coefficient(Kc)with film mulching are considerably reduced by 10.21% and 7.42%, respectively.
2020 Vol. 38 (7): 731-737 [Abstract] ( 1 ) [HTML 1KB] [ PDF 1581KB] ( 25 )
738 Prospects for development of water saving irrigation equipment and technology in China
LI Yangbin*,LIU Junping
The achievements in irrigation and drainage in China in the past 70 years are reviewed in terms of irrigation and drainage facilities, irrigation and drainage management systems and investment policies, respectively. With the increase in irrigation area, irrigation and drainage facilities have greatly improved grain yield and agricultural production capacity of China. The irrigation and drainage management system has experienced huge changes, i.e. from the collective management of farmers to the management of state-owned back-bone institutions, which promoted the rapid development and healthy operation of irrigation and drainage projects. Investment policies served water conservancy infrastructure effectively. However, presently in China, there are still problems such as poor utilization efficiency of irrigation water, small proportion of water and fertilizer integrated irrigation farmland and low extent of informatization of irrigation system, which are far behind the development of high-quality agricultural production. Combined with the strategic needs of national food and ecological security, the future opportunities and challenges in water-saving irrigation equipment and technology to China are proposed in a few aspects, namely, water-saving transformation of large and medium-sized irrigation districts, water and fertilizer integrated water-saving irrigation equipment and technology, spray and drip irrigation, pipeline water delivery irrigation and pump station upgradation. In order to promote the development of water-saving irrigation industry in China, taking the measures, such as strengthening the theoretical research and independent innovation of irrigation and drainage equipment, developing efficient, energy-saving and environmental protection technologies and products, and improving industrial informatization, intelligence and networking, is the inevitable trend to achieve agricultural mo-dernization.
2020 Vol. 38 (7): 738-742 [Abstract] ( 0 ) [HTML 1KB] [ PDF 1063KB] ( 38 )
743 Influence of elastic diaphragm on hydraulic performance of pipe-type pressure compensating emitter and simulation of internal fluid structure interaction
XU Yao,SU Yanping,YANG Peiling*,REN Shumei
In order to study the influence of elastic diaphragm parameters on the hydraulic performance of pipe-type pressure compensating emitter and the internal compensating principle of compensation pressure chamber, the pressure compensating emitter of type supertif-03120-0003 is used as the prototype and a pipe-type emitter experimental model is fabricated with 3D printing. The pressure-flow curve of the model was measured at inlet pressures ranged in 0-350 kPa. The effects of thickness and hardness of the natural rubber elastic diaphragm on the hydraulic performance of the emitter were analyzed. A fluid-structure interaction(FSI)analysis on the compensating principle and hydraulic performance in the emitter was launched in ADINA software. The results showed that when the thickness of the elastic diaphragm was constant, the discharge flow and compensating threshold pressure of the emitter all increased with increase of the elastic diaphragm hardness. When the hardness was fixed, the discharge flow and compensating threshold pressure both showed an increasing trend with increase of the thickness. The growth rate of the emitter discharge flow was decreased beyond a threshold pressure, and finally the pressure-flow relationship curve tended to be flat. For this internal structure of the emitter, the elastic diaphragm was subject to an optimal combination of hardness and thickness, namely thickness 1.4 mm, hardness 50HA. The predicted pressure-flow curve was in good agreement with the measured value, and the maximum deviation between them was less than 5%, indicating that ADINA software was proper in FSI analysis of compensating principle and hydraulic performance for the emitter. This method has provided a visualization way for research and development of emitters with pressure compensation.
2020 Vol. 38 (7): 743-750 [Abstract] ( 1 ) [HTML 1KB] [ PDF 2553KB] ( 25 )
751 Structure optimization and test of three-way pulse jet tee
XUE Zilong,WANG Xinkun*,FAN Erdong,XU Shengrong,WANG Xuan,ZHANG Chenxi
In order to improve the hydraulic performance of three-way pulse jet tee and the uniformity of drip irrigation, the structure of a three-way pulse jet tee with 15 mm inlet width is optimized based on CFX numerical simulation technology. The half difference in width between nozzle and tee inlet s, distance between tee inlet and daughter branch inlet H, daughter branch wall curvature radius r and tee inlet wall inclination angle β were selected as influencing factors, then nine cases were generated by using four-factor and three-level orthogonal design table. A 100 kPa inlet pressure was used as the boundary condition and the flow rate through the daughter branches was served as the evaluation criterion. The optimum structural dimensions of the three-way jet tee are s=5.5 mm, H=113 mm, r=13 mm and β=10°. A hydraulic performance test was conducted on this optimized three-way jet tee. When the inlet water pressure is 100 kPa, the pulse frequency of the jet in the tee is 148 min-1, the hydraulic head amplitude is 37.9 kPa, the hydraulic head loss is 16.7 kPa, and the outlet flow rate is 0.698 L/s. When the tee is connected with a 60 m long drip irrigation tape, the uniformity coefficient of irrigation is improved by 2.78% and the flow rate deviation is lowered by 4.72% in comparison with the ordinary three-way tee. This study can provide a theoretical basis for research, development and application of the pulse jet drip irrigation system.
2020 Vol. 38 (7): 751-756 [Abstract] ( 1 ) [HTML 1KB] [ PDF 1159KB] ( 33 )


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