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Journal of Drainage and Irrigation Machinery Engin
2020 Vol.38 Issue.3
Published 2020-03-25

2020 Vol. 38 (3): 1- [Abstract] ( 3 ) [HTML 1KB] [ PDF 2479KB] ( 41 )
2020 Vol. 38 (3): 2- [Abstract] ( 1 ) [HTML 1KB] [ PDF 1242KB] ( 62 )
217 Effect of slurry flow rate on cavitation characteristics of deep-sea mining pump
XU Hailiang,*,PENG Neng,YANG Fangqiong,
The three-dimensional fluid domain model of a two-stage deep-sea mining pump was established,then the effect of slurry flow rate on cavitation characteristics of the pump was simulated and analyzed by computational fluid dynamic based on the Fluent software, Euler multiphase flow model, Schnerr-Sauer cavitation model and RNG k-ε turbulence model.The particle size in the slurry is d=20 mm, solid volumetric concentration is CV=8%, and the pump rotational speed is n=1 450 r/min.Specially, the cavitation characteristics of the slurry pump were explored at different slurry flow rates in terms of pressure distribution curve, vapor volume fraction contour and hydraulic performance. The performance was compared with the experimental data measured by us.The aim of this study is to provide theoretical basis for the cavitation characteristics of slurry pumps.The results show that there is a notable low-pressure zone near the blade leading edge in the first stage impeller and the size of the zone shrinks with increasing flow rate.The area of vapor volume fraction sharesa similar rule to the low deep-sea pressure zone.Areverse flow phenomenon appears in the cavity, which can intensify the instability of flow field.As the flow rate increases, the net positive suction head rises and the cavitation phenomenon becomes less obvious, and its impact on the pump head is minor.
2020 Vol. 38 (3): 217-223 [Abstract] ( 9 ) [HTML 1KB] [ PDF 2512KB] ( 110 )
224 Effect of blade tip clearance on cavitating flow in mixed-flow pump
LI Yibin*,HE Hui,FAN Zhaojing,LI Jianzhong
Cavitating flows in a mixed-flow pump are numerically simulated using CFD software based on SIMPLEC algorithm and structured-mesh. The standard SST k-ω turbulence model and homogeneous flow cavitation model are adopted to investigate the influence of tip clearance on cavity stability in the impeller and obtain the optimum range of tip clearance. The results show that the blade tip clea-rance has a significant effect on the cavitation characteristics in the mixed-flow impeller; specially, the turbulence scale and intensity of tip leakage vortex increase but the critical cavitation number decreases gradually with increasing tip clearance under part-load flow conditions. When the critical cavitation number is 0.357, a larger tip clearance can suppress the inception of cavitation on blade surfaces. When severe cavitation occurs at 0.123 cavitation number a smaller tip clearance can inhibit large scale bubbles on blade surfaces. At a small tip gap, these bubbles are attached to blade suction side and become stable. With increase of tip clearance, the cavity shedding area is migrated to the primary flow zone and the bubbles are accumulated in the middle of blade suction side, and the vapor vo-lume fraction and cavity thickness are increased gradually.
2020 Vol. 38 (3): 224-229 [Abstract] ( 7 ) [HTML 1KB] [ PDF 2597KB] ( 52 )
230 Numerical analysis and experiment on eddy current loss in amagnetic coupling
WANG Jiaqiong,*,WANG Kai,SUN Jingru,ZHAO Ruijie,TONG Kai,BAI Yuxing
The transient magnetic field of a cylindrical magnetic coupling was numerically simulated to obtain the influencing rules of speed, containment can material andslip angle on eddy current loss in magnetic couplings. It was shown that the eddy current loss increasesin several folds with increasing rotational speed, at 3 000 r/min, for example, it was about 24 times that at 500 r/min. Additionally, the loss depends on the conductivity of containment can material. The conductivity of titanium plate TP340 is 1.65 times that of 304SS, as a result, the eddy current loss of TP340 is 1.61 times that of 304SS.In one magnetic pole period, a 1°slip angle increase leads to an about1% eddy current loss rise. The experimental results showed thatthe ratio of the eddy current loss in the containment canof 304SS at 3 000 r/min to that at 500 r/min is 23.0, while the ratio is 24.6 in the containment canof TP340. The eddy current loss is decreased with decreasing coupling length, especially at high speeds. When the coupling length is decreased by 10 mm, the eddy current loss is decreased by 3.6% at 500 r/min.The eddy current loss is decreased by about 10% at 3 000 r/min. Compared the experimental results, the numerically simulated eddy current lossesare consistent with the former.
2020 Vol. 38 (3): 230-235 [Abstract] ( 8 ) [HTML 1KB] [ PDF 2919KB] ( 83 )
236 Influence of balancing drum clearance on axial thrust and pressure in rear chamber of last stage impeller of multistage centrifugal pump
QIAN Chen*,YANG Congxin,HU Xiaojie,ZHANG Yang,HOU Kaiwen
In compressible viscous fluid flows in an axial-split multistage centrifugal pumps were numerically calculated by using the Fluent software based on the SST k-ω turbulence model at six drum radial clearances 0, 0.1, 0.2, 0.3, 0.4, 0.5 mm to study effects of the clearance on pump efficiency, axial thrust and pressure in the rear chamber of the last stage impeller under design condition.The calculated results show that the fluid pressure in the rear chamber increases gradually in the radial direction, and the pressure on the hub nearly impeller outlet is distributed more unevenly along the circumferential direction with increasing drum clearance. The minimum pressure in the mid-span plane of the rear chamber is declined with increase of drum clearance, but the maximum pressure increment along the radius is the lowest at 0.2 mm clearance, then rises rapidly with increasing clearance. The axial thrust is the smallest at 0.3 mm clearance.The pump efficiency decreases with increasing leakage flow rate through the drum gap; particularly, as the leakage flow rate is 0.887 kg/s, the efficiency has been lowered significantly.
2020 Vol. 38 (3): 236-240 [Abstract] ( 5 ) [HTML 1KB] [ PDF 4056KB] ( 54 )
241 Layout position of bionic non-smooth structure on blades of centrifugal pump
DAI Cui,CHEN Yiping,DONG Liang*,WANG Zhaoxue
In order to explore the correlation between drag reduction rate and layout position of bionic non-smooth structure, and the sensitivity of hydraulic efficiency of centrifugal pump to the structure, bionic non-smooth structures were decorated on six different locations on blade two surfaces of a centri-fugal pump, respectively; and six designs were resulted.The hydraulic characteristic parameters and internal flow of the centrifugal pumps with these designs were studied numerically by using ANSYS CFX software at a duty point.An optimal design was decided by comparing hydraulic efficiency and drag reduction rate among six designs. Then, the optimal layout design was compared and analyzed against the existing usual layout position of bionic non-smooth structure in the whole range of flow rate.Finally, the influence of roughness on the performance and flow in the pumps were clarified in terms of the same layout position of bionic non-smooth structure.The results show that the hydraulic efficiency of the pumps with bionic non-smooth structurewas less or equal to the efficiency without the structure, but the average shear stress on the blade surfaces was lowered by about 12.7%. The bionic non-smooth structure unit in any position could produce a drag reduction effect in some degree, however, the drag reduction effect produced by an adjacent bionic non-smooth unit did not show a linear relation of superposition in an intersected position. In the whole range of flow rate, the layout position of bionic non-smooth structure in the middle of blade suction side always leads to both higher hydraulic efficiency and larger drag reduction rate, compared with the layout arranged near the outlet on blade suction side. Additionally, the hydraulic efficiency change and drag reductionrates in two layouts showed a similar trend versus flow rate.Unfortunately, the efficiency change rate was too tiny to be considered as a standard to evaluate the bionic non-smooth structure, while the drag reduction rate was substantial. It is suggested that the bionic non-smooth structure should be arranged in the position suffering from the largest shear stress for a better performance and pit elements in the structure should be apart with large enough spa-cing to increase the average drag reduction rate. The results demonstrated that even though a rough surface could form a low-velocity layer near a wall like a bionic surface, the drag reduction was unachie-vable because only macroscopic bionic units play a positive role in drag reduction. The results revealed that the layout position has limited influence on the hydraulic efficiency of centrifugal pump.For a fixed number of pits applied, the pits should be placed in the position as close as possible where the maximum shear stress is experienced.
2020 Vol. 38 (3): 241-247 [Abstract] ( 1 ) [HTML 1KB] [ PDF 2304KB] ( 48 )
248 Fatigue analysis of hydro-turbine head cover bolts based on prototype vibration measurement
LIAN Jijian,WANG Tingjie,WANG Haijun*,WANG Hongzhen
Taking a high-head hydropower plant in China as an example, vibration of the head cover in a real hydro-turbine was mearued and analyzed under steady variable load, startup and shutdown, load-rejection conditions. A fininte element model was established for the head cover and connecting bolts, the fluctuating presure load on the head cover was detemiend inversely by making using finite element dynamic analysis base on the measured data. Fatigue of the bolts was anlayzed in normal ope-rating and load-rejection conditions by utilizing linear fatigue cumulative damage theory and rainfall counting method and by adopting actual operation modes of the turine in one year. The results indicate that the pressure fluctuating double amplitude is about 19.3 m on the head cover under 100 MW steady operating condition, which is 5.6 times that under 600 MW condition. Fatigue life of the bolts decreases sharply along with increase of survival rate. When the survival rate is increased from 95% to 99% under 100 MW condition, the fatigue life is decreased to 2.415×107 from 6.488×107, and the reduction is 62.8%. Taking 99% as a survival rate criteria, the fatigue life of the bolts is 7.494×105 under load-rejection condition, which accounts for only 3%-5% of that under various steady load conditions.
2020 Vol. 38 (3): 248-253 [Abstract] ( 5 ) [HTML 1KB] [ PDF 1615KB] ( 64 )
254 Water hammer protection characteristic of combined air vessel and pressure relief valve
LI Nan,ZHANG Jian*,SHI Lin,CHEN Xuyun,ZHANG Xiaoying
A water hammer protection scheme, i.e. combined air vessel and pressure relief valve installation, was proposed, then the mathematical model for the whole system including air vessel, hydraulic control butterfly valve and pressure relief valve was established based on the method of characteristics to simulate the transient pressure variation process in the system during pump stopping period. Based on a specific water supply project, three protection measures, such as single air vessel scheme, combined air vessel and hydraulic control butterfly valve scheme and combined air vessel and pressure relief valve scheme, were assessed in terms of water hammer effect during pump stopping period. Specially, a sensitivity analysis was carried out on the opening and closing rules of the pressure relief valve as the shape parameters of the air vessel volume were fixed. The results showed that the combined air vessel and hydraulic control butterfly valve scheme is unfavorable to positive and negative water hammer protection, and the combined air vessel and pressure relief valve scheme has a good effect on both positive and negative water hammer protection. Compared with single air vessel protection scheme, the maximum stress in the high-pressure pipe wall was decreased from 1.343 MPa to 1.087 MPa, and the safety margin was increased by 9.4%. The volume of air vessel was reduced from 200 m3 to 160 m3. The pressure relief valve should be opened fully within 5 seconds, and the duration after opening should be close to one phase length(the time for traveling one wavelength).
2020 Vol. 38 (3): 254-260 [Abstract] ( 3 ) [HTML 1KB] [ PDF 1674KB] ( 74 )
261 Management problems and countermeasures of gravity flow ecological filter in sponge campus construction
LIU Shuomin,WU Rongfang,LIU Cancan,WANG Dongmei,XIE Qingjie*
Based on a sponge campus gravity flow ecological filter project, the problems in the project, such as anti-blocking management and plant management and so on, were analyzed and discussed briefly. The results showed that the pretreatment processes such as filter screen filtration, anaerobic precipitation, coagulation and sedimentation were effective in intercepting particulate pollutants in rainwater runoff. Medium local replacement methods, namely mechanical removal, medium solidification and medium covering could better solve blocking problem. The implementation of operating-break and operating-in-shift, regular cleaning and desilting was also conducive to the normal performance of gra-vity flow filter. Since plants were the most important part of purification function and ecological landscape in gravity flow ecological filters, the plant specific selection principle, planting method and reasonable density were investigated. A planting scheme was proposed, in which mosquito repellent plants are planted in the intake unit, algae resistant plants in the middle unit, algae resistant and bactericidal plants in the outlet unit; further, the planting density and daily management method etc were also put forward for some typical plants. Eventually, suspended substances and organic load in the water of ecological filter can be reduced to effectively prevent the ecological filter from blockage and maintain its stability.
2020 Vol. 38 (3): 261-265 [Abstract] ( 4 ) [HTML 1KB] [ PDF 1640KB] ( 68 )
266 Flowmaster-based optimization study of water supply pipe network with different valve openings
FU Qiang,YU Jianen*,YAN Qiang,HAO Guoshuai,SHA Long,ZHU Rongsheng,WANG Xiuli
The influence of valve opening on optimization of a water supply pipe network system was studied by using Flowmaster software to improve the hydraulic performance of the network. The mode-ling process of basic components, such as pipeline, gate valve and valve opening controller, was provided, then several sets of model parameters were simulated and the variation of resistance factor in the system was analyzed and contrasted at different valve openings. A fluid pipeline system was taken as the study object, and the whole system was modeled firstly. Then the resistance factors of the gate valve and pipeline were optimized. Finally, the influence of valve openings on the pipeline resistance was explored according to different water supply conditions, and the optimum valve opening was obtained. The results show that when the water supply network system is under large and small flow operating conditions, respectively, the valve opening should be comprehensively adjusted based on user actual water demand, valve and pipeline resistance factors to appropriately reduce the hydraulic loss in the network and optimize the hydraulic performance of the system.
2020 Vol. 38 (3): 266-270 [Abstract] ( 4 ) [HTML 1KB] [ PDF 1916KB] ( 72 )
272 Influence of wastewater mixer setting angle on flow field in sewage treatment pool
ZHANG Zhi,ZHEN Yuan*,JIANG Jieqing,LI Chengyi
An unreasonable setting angle can result in a wastewater mixer to consume much more po-wer. Bearing this problem in mind, three-dimensional turbulent fluid flows in a sewage water treatment pool with two wastewater mixers at various setting angles were simulated using Fluent software to optimize mixer design and reduce sludge deposition at the pool bottom due to low water velocity. At first, the three-dimensional fluid domain model was established in UG software, then the steady fluid flow field was calculated in unstructured tetrahedron grids based on the N-S equations, standard k-ε turbulence flow model and SIMPLEC algorithm. The average velocity and velocity distribution within the pool were compared across various setting angles. Consequently, flow mixing effect was assessed by employing gray correlation method in terms of low velocity zone occurrence rate at the pool bottom. At the same time, the relationship between vortex structure and mixing energy consumption was studied. The results show that when the angle is 50° the average fluid velocity at the bottom is increased by 17.6%, the volume-averaged velocity is increased by 6%, and the low velocity zone occurrence rate at the bottom is reduced by 12%, suggesting the best transporting and mixing effect. Additionally, the vortex phenomenon has a significant impact on stirring effect. The smaller the number of vortices and the larger the scale of a single vortex, the lower the energy consumption and the more sTab. the fluid flow, the better the mixing effect. Altering the setting angle of a wastewater mixer can improve fluid flow pattern in a sewage water treatment pool, suppress sludge deposition and reduce energy consumption of vortex, eventually to achieve an aim with advanced transporting and mixing effect.
2020 Vol. 38 (3): 272-276 [Abstract] ( 4 ) [HTML 1KB] [ PDF 3193KB] ( 48 )
277 Transient heat transfer characteristics of air-array-jet impingement with different nozzle arrangements on high-tempera-ture flat plate in small jet-to-plate distance
LI Meixiang,ZHU Keqian,XIE Yu,CAI Tingting,YUAN Ningyi,DING Jianning,*
Numerical studies on transient heat transfer characteristics of air-array-jet impingement are presented, for a small jet-to-plate distance and a large temperature difference between nozzles and plate in the paper. The dimensionless jet-to-plate distance(H/D)is 0.2, and non-dimensional nozzle-to-nozzle spacing(S/D)is 3,4,5 and 6, respectively. It is found that the quenching time is shortened at a constant total mass flow at air jet inlet m·(m·=218.21 kg/h), and the heat transfer uniformity is deteriorated as S/D increases. However, the added reversed-flow nozzles can shorten the quenching time of the glass plate considerably with a modest change in the heat transfer uniformity. The results at variable m· are the same as those at a fixed m·. Furthermore, the arrangement of nozzles is also discussed in this paper. Based on these results, an appropriate proposal for ultra-thin glass tempering process is presented.
2020 Vol. 38 (3): 277-284 [Abstract] ( 2 ) [HTML 1KB] [ PDF 3263KB] ( 29 )
285 System dynamics model-based simulation of agricultural water resources supply and demand balance in changing environments
SU Xiaoling,*,XIE Juan,ZHOU Zhenghong,
A system dynamics model for supply and demand balance of agricultural water resources has been established using system dynamics software Vensim-Dss to simulate variations in agricultural water supply, demand and deficit in a changing environment. The social and economic development and climate changing scenarios were considered in the model and the impacts of changing environment on the supply and demand balance of agricultural water resources were explored. In terms of Shiyang River Basin, the results show that the extent of influence of climate change on the future agricultural water supply differs from that on the water demand. After 2033, however, the variation trends of the agricultural water supply in A2 and B2 climate scenarios are identical. The response of the agricultural water resources system to climate change in one administrative district is different from that in the other district significantly. In Jinchang Administrative District, for example, the water deficit ratio in Scenario A2 is greater that in Scenario B2, and it will arrive at 32.0% and 28.6%, respectively, in 2029 and 2038. In Scenario B2, mild water deficit will start to occur onwards 2021, and moderate water deficit should only appear in 2023 and 2039, with 30.7% and 30.7% water deficit ratios, respectively. Regarding to Wuwei Administrative District, the water deficit ratio in Scenario A2 is smaller that in Scenario B2. Specially, in Scenario A2, moderate water deficit just appears in 2038 with 24.9% water deficit ratio. In Scenario B2, however, more years will suffer from moderate water deficit, especially, the year 2023 can be subject to the most severe water shortage with a deficit ratio as large as 33.2%. These results can provide guidance on regional water utilization planning and agricultural development planning in a changing environment.
2020 Vol. 38 (3): 285-291 [Abstract] ( 7 ) [HTML 1KB] [ PDF 4086KB] ( 37 )
292 Effects of biochar on soil water transport characteristics of Heilu soil
WANG Youqi,BAO Weibin,BAI Yiru,*,LU Xuee,XIA Zishu,YANG Fan,ZHONG Yanxia,
Biochar applied in soil can alter characteristic parameters of soil water migration in Helu soil in the southern Ningxia mountain region. In the paper, a typical Heilu soil in the region was selected to the study object. Then, a soil amendment-biochar was added into one-dimensional vertical and horizontal soil columns in four proportions, such as 0%, 1%, 2% and 3%, to explore the change in soil water transport characteristics, namely, infiltration rate, saturated volumetric water content, saturated hydraulic conductivity, and saturated diffusivity. The results showed that soil water content in the soils with 1%, 2% and 3% biochar was increased by 2.98%, 6.45% and 7.94% compared with the plain soil. The Philip model can reflect soil water transport process in different biochar mixing proportions more exactly than the Kostiakov model. The saturated volumetric water content in the amended soils with 1%, 2% and 3% biochar was increased by 5.05%, 8.33% and 9.85%, respectively, and the sa-turated hydraulic conductivity was decreased by 45.71%, 62.86% and 74.28%, respectively. The parameter a in the Van Gencuhten model for the amended soils with 1%, 2%, and 3% biochar was reduced by 31.90%, 29.25%, and 19.23%, and the parameter n in the model was reduced by 0.28%, 0.16%, and 0.66%, respectively. The saturated diffusivity in the amended soils with 1%, 2%, and 3% biochar was reduced by 58.46%, 77.96% and 89.28% compared with the plain soil, respectively. These facts suggest that biochar can improve soil structure, but also can increase soil volumetric water content and improve soil water holding capacity.
2020 Vol. 38 (3): 292-297 [Abstract] ( 2 ) [HTML 1KB] [ PDF 1737KB] ( 56 )
298 Response of water-salt migration to salty and fresh water alternate irrigations in silty loam
ZHU Jinjin,SUN Junna,ZHANG Zhenhua*,YANG Mao
In this paper, effects of irrigation intervals and salinity on water infiltration dynamics and salt distribution in the silty loam from the Yellow River Delta were investigated. Laboratory simulation experiments were conducted on soil columns and the cumulative infiltration, infiltration duration and water-salt distribution in the soil were monitored in twelve irrigation treatments in terms of four irrigation intervals(0, 30, 60 and 90 min)and three salinity levels(3, 6 and 9 g/L). The results showed that the duration of water infiltration became longer significantly with increasing irrigation interval in the same amount of infiltration. There was no statistically significant difference in the mean soil water content between the alternate irrigations with salty water in 3, 6 and 9 g/L salinity respectively. However, the mean soil salt content in the irrigation treatment with 3 g/L salinity was lower than that in the irrigation treatments with 6 and 9 g/L salinity; further, the mean soil salt content in the treatments with 90min irrigation interval was much lower than the treatments with the other irrigation intervals. Overall, the alternate irrigation with salty water in 3 g/L salinity and a longer interval is beneficial to reducing soil salt content in the studied region.
2020 Vol. 38 (3): 298-303 [Abstract] ( 2 ) [HTML 1KB] [ PDF 1704KB] ( 36 )
304 Experiment on variation characteristics of hydrogen and oxygen stable isotopes of Lycium barbarum in Ningxia under different irrigation conditions
TANG Ying,XU Ligang*,WANG Huaibo,BAO Ziyun
Considering the Lycium barbarum in Ningxia as research object, the rainfall data, root system and stem sample of the Lycium barbarum under different irrigation quotas and precipitations in the experiment filed were collected, then the δ18O and δD values were measured to analyze the variation characteristics of stable isotope in the Lycium barbarum. The IsoSource model was used to calculate soil water utilization efficiency of each potential water sources to the Lycium barbarum. The results show that there is a good linear relationship between δD and δ18O in precipitation and a line regression equation was built for the meteoric water line in the experimental field. The soil moisture content has a ne-gative correlation with the corresponding δD of the Lycium barbarum under different irrigation quotas(20-60 cm), and the δD value decreased with deepening soil layer. The variation pattern of δD in different soil layers was similar to that in 20 cm below 5 mm precipitation, where the maximum δD value was -64.39 ‰. The Lycium barbarum mainly utilizes the water in the surface soil layer(0-20 cm)and middle soil layer(20-40 cm)respectively with utilization efficiencies of 35.2% and 25.1%. The value of δD in 20-60 cm was richer(>-65.20 ‰)when the precipitation was 13.9 mm. The Lycium barbarum can make use of soil water content in 0-60 cm deep soil layer, especially the water utilization efficiencies in 1-20, 20-40 and 40-60 cm layers are 22.4%, 25.3% and 23.2%, respectively. The conclusion can provide a reference for reasonable irrigation of Lycium barbarum in arid regions.
2020 Vol. 38 (3): 304-309 [Abstract] ( 3 ) [HTML 1KB] [ PDF 1659KB] ( 115 )
310 Effects ofoxygation techniques on growth and physiology of vegetable under subsurface drip irrigation
ZANG Ming,LEI Hongjun*,BHATTARAI Surya,BALSYS Ron,XU Jianxin
Perched water often leads to a decrease in soil aeration in subsurface drip irrigated crop roots, whereas aerated subsurface drip irrigation(ASDI)provides a source of oxygen in a root environment that suffers from temporal hypoxia and unlocks yield potentials of crops. With Chinese cabbage as test crop, five irrigation treatments were used including Mazzei air injector(MAI)cyclic aeration, 15 mg/L of hydrogen peroxides(H2O2), fluidic oscillator(FO), oxygen concentrator(OC)and a control treatment(CK). The experiment was carried out during September 23, 2015 to October 31, 2015 at the Central Queensland University, Australia(23°22′0.345″S latitude, 150°31′0.53″ E Longitude), and subsurface drip irrigation was implemented to systematically monitor soil respiration, crop growth and physiological indexes to clarify the effect of different oxygation techniques on growth and development of potted Chinese cabbage. Compared with the control treatment, the soil respirations in treatments MAI, H2O2, OC and FO increase by 65.87%, 42.07%, 66.79% and 111.62% respectively compared with CK. ASDI improves the leaf chlorophyll content in treatments MAI, OC and FO. The photosynthetic rate, stomatal conductance and transpiration rate are enhanced by SADI. The photosynthetic rates in MAI, H2O2, OC and FO increase by 868.62%, 794.14%, 778.67% and 650.19% compared with CK. The stomatal conductance in MAI, H2O2 and OC increases by 157.14%, 128.57% and 85.71%, the transpiration rates in MAI, H2O2 and OC increase by 55.61%, 32.38% and 19.58%, and there is not statistically significant difference between other treatments. The yield is significantly increased, and the water utilization efficiency(WUE)is improved, too. The yield increases by 56.36% and 38.72% respectively in treatments MAI and H2O2, and the WUE in MAI and H2O2 increases by 48.96% and 36.46% compared with CK. The beneficial effects of ASDI are mediated through greater root activity, especially the root-shoot ratio increases by 49.61% in MAI. In conclusion, ASDI improves the hypoxic environment in crop roots, promotes the growth of Chinese cabbage, enhances the soil respiration and increases the yield as well as water utilization efficiency. Among four treatments, MAI is ranked in the first place.
2020 Vol. 38 (3): 310-317 [Abstract] ( 5 ) [HTML 1KB] [ PDF 1419KB] ( 56 )
318 Design and experiment of variable liquid fertilizer applicator for deep-fertilization based on ZigBee technology
XUE Xiuyun,ZHANG Bin,ZHANG Zelong,LIN Dongting,SONG Shuran,*,LI Zhen,HONG Tiansheng,
To improve the efficiency of liquid fertilizer application, a variable liquid fertilizer applicator for deep-fertilization based on ZigBee technology is elaborated. A host computer with remote control software and a STM32F103RET6 microcontroller were combined to measure and control the li-quid fertilizer output: through the ZigBee wireless communication network, this system realized the collection of liquid flow information in real time using flow meter while monitoring the liquid level; and an incremental PID control algorithm was used to dynamically adjust the converter frequency for reaching the set liquid fertilizer flow accurately. In the meanwhile, the performance experiment in the field analyzed and compared how parameters like the fertilizer application depth, the converter frequency, the fertilization pressure and the opening degree of back-water valve influenced the accuracy and the stabi-lity of the liquid variable deep-fertilization control. On the basis of the test data, a precise flow control mathematical model is also established. As the result, the orchard experiments indicated: the applicator accuracy is able to reach 99.52% and the maximum liquid fertilizer consumption in each fertilization process is 0.22 L〓 /min; with the fertilizer application depth changing, the maximum flow output difference is 0.15 L〓 /min and the converter frequency difference is 0.79 Hz. When adjusting the opening degree of back-water valve to confirm the optimum working parameters, which means the valve opening degree is 40%, the system works the most stably while owns the minor flow output difference and the low liquid fertilizer consumption.
2020 Vol. 38 (3): 318-324 [Abstract] ( 2 ) [HTML 1KB] [ PDF 2370KB] ( 45 )


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