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Journal of Drainage and Irrigation Machinery Engin
 
2022 Vol.40 Issue.6
Published 2022-06-25
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2022 Vol. 40 (6): 1- [Abstract] ( 37 ) [HTML 1KB] [ PDF 31606KB] ( 405 )
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2022 Vol. 40 (6): 2- [Abstract] ( 32 ) [HTML 1KB] [ PDF 1064KB] ( 342 )
541 Numerical analysis of hydrodynamic noise characteristics of single-blade centrifugal pump
LANG Tao,JIN Licheng*,LIU Yutao,CHEN Keqiang,XU Enxiang
Based on LIGHTHILL acoustic analogy theory and FW-H equation, computational fluid dynamics and computational acoustics were used to solve the internal noise of a single-blade centrifugal pump, and the sound source characteristics of the internal flow field under different flow conditions were explored. A hybrid numerical simulation method and the SST k-ω turbulence model were adopted to perform unsteady simulation of the centrifugal pump. The sound source information was exported, and acoustic calculations was performed. The internal field noise of single-blade centrifugal pumps at different flow rates was analyzed. The results show that the energy of the pressure pulsation of the single-blade centrifugal pump is mainly concentrated in the blade frequency and its harmonic frequency in the lowfrequency range. The energy of the internal noise is mainly concentrated in the low frequency band, and the energy of the noise component is higher at the blade frequency and its harmonic frequency. With the increase of the flow rate, the flow pattern of the flow channel in the volute and the impeller is gradually improved, and the secondary flow and flow separation phenomenon was reduced. It results in an obvious downward trend in low frequency harmonic noise. According to the frequency spectrum analysis of the sound power level under different flow rates, it can be found that the distribution characteristics of the pressure pulsation have a direct effect on the internal hydrodynamic noise of the single-blade centrifugal pump.

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2022 Vol. 40 (6): 541-548 [Abstract] ( 30 ) [HTML 1KB] [ PDF 7003KB] ( 616 )
549 Internal flow characteristics of submersible sewage pump based on specific area regulation
CHEN Jianhua,ZHOU Ling,ZHANG Fan,FANG Xin,LI Yibin*
In order to improve the hydraulic performance and operating efficiency of the pump, the good matching of geometric parameters between impeller and volute of submersible sewage pump was studied. Taking a submersible sewage pump with specific-speed ns=261 as the research object, three specific area control schemes are designed according to the different placement angles of volute tongue. The internal flow field of three schemes pump was numerically calculated by computational fluid dynamics method. The velocity distribution, static pressure distribution, turbulent kinetic energy distribution, dissipation rate distribution of turbulent kinetic energy and volute hydraulic loss under three specific area control schemes were compared and analyzed, and the correctness of numerical calculation results was verified by experiments. The results show that the change of specific area is the main factor affecting the hydraulic performance of the volute when the placement angle of the tongue changes within 5°. The value of specific area should be given priority to be near 1.0 when volute is designed. When the tongue placement angle is 42°-44° and the specific area varies in the range of 1.0-1.2, the ope-ration efficiency of the submersible sewage pump remains basically constant. The research results can provide some references for the optimal design of submersible sewage pump.

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2022 Vol. 40 (6): 549-555 [Abstract] ( 31 ) [HTML 1KB] [ PDF 5225KB] ( 446 )
556 FTLE evaluation method for mixing ability of jet pump
ZHAO Kai,CHENG Huaiyu,LONG Xinping,JI Bin,LAI Xu
In order to study the spatial distribution characteristics and influencing factors of jet pump mixing capacity, the mixing capacity of jet pump was evaluated and analyzed by using finite time Lyapunov exponent(FTLE). Firstly, the time and space discrete velocity vector field in the computational domain is obtained by numerical simulation. Then, using particle tracking technology and virtual neighbor node FTLE solution method, the ftle solution program is developed; finally, the mixing capacity of a typical jet pump is deeply analyzed based on FTLE field. The results show that the mixing capacity of jet pump in stable operation remains relatively stable and basically does not change with time; the average mixing capacity in the axial direction of the jet pump first increases with the diffusion of the high mixing capacity area of the shear layer, and then decreases with the attenuation of the overall mi-xing capacity; under the operating condition of larger flow ratio, although the jet pump can enter the state with strong mixing capacity in advance, the length of the watershed with continuous high-intensity mixing capacity becomes shorter. Considering the intensity of mixing capacity and the length of high-intensity mixing capacity watershed, the mixing capacity of jet pump can be evaluated more accurately.

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2022 Vol. 40 (6): 556-562 [Abstract] ( 56 ) [HTML 1KB] [ PDF 5324KB] ( 433 )
563 Investigation on wicket gate closure law considering servomotor characteristics
XU Minjie,CHEN Sheng*,YANG Sen,ZHANG Jian,WANG Jing
In order to explore the influence of servomotors characteristics on the extreme value and time history of volute, draft tube pressure and unit speed in the process of wicket gate closure, a diversion hydropower station in China was taken as the research object to establish the calculation simulation model of hydraulic transition process based on the characteristic line method, and the hysteresis and buffer process in the process of wicket gate closure was considered, then the model was verified combined with the real machine load rejection experimental data.The comparative analysis between the wicket gate closure law considering servomotor charateristics and the generalized broken line closing law and the hysteresis time sensitivity analysis was carried out. The results show that the hysteresis process mainly affects the speed rising rate of the unit. The longer the hysteresis time, the greater the speed rising rate, but has little effect on the time history and extreme value of volute pressure and draft tube pressure. The buffering process has no effect on the extreme value of regulation and maintenance parameters due to its late occurrence time, but has a great impact on the time history of volute pressure and draft tube pressure after the last closing of guide vane. The research results can provide reference for the simulation of guide vane closing law of unit in the hydraulic transition process.

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2022 Vol. 40 (6): 563-569 [Abstract] ( 41 ) [HTML 1KB] [ PDF 2868KB] ( 487 )
570 Influence of variable speed pumped-storage unit operating speed on load rejection transient process
ZHANG Wenke,ZHANG Jian,YU Xiaodong*,CHEN Sheng
In order to analyze the influence of the initial running speed of the variable speed pumped-storage unit on the load rejection transient process by adjusting the parameters of the guarantee, aiming at the operation characteristics of variable speed pumped storage unit, based on the theory of one-dimensional transient flow characteristic line method, the initial variable speed pumped-storage power station running speed calculation and transient process simulation model was established, combined with the engineering example, the influence of unit running speed on power generation efficiency under different head operating conditions, and the influence of variable speed pumped storage unit starting running speed on water hammer pressure and speed rising rate under the accident load rejection condition were studied, and the reasons for those were explained. The results show that when the variable speed pumped-storage unit is running at rated output under high water head and rated water head, with the decrease of initial operating speed, the maximum speed rising rate increases after the accident load rejection, and the water hammer pressure increases. The reason is that the change of initial speed of variable speed pumped-storage unit results in the change of torque and flow rate during the load rejection. The research results can provide reference for the selection of running speed and optimization of maintenance parameters in the transition process of load rejection in similar projects.

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2022 Vol. 40 (6): 570-575 [Abstract] ( 38 ) [HTML 1KB] [ PDF 1810KB] ( 435 )
576 Experimental study on effect of geotextile filter layer on flow of perforated pipe
XIE Shuhua,LIU Huanfang*,HUANG Haitao,YE Fang
In order to explore the influence of the geotextile filter layer on the flow rate of the perforated pipe, indoor experiments were combined with theoretical analysis. 5 kinds of staple fiber needle-punched nonwoven geotextiles with 4 kinds of areal density and 4 kinds of layers were set up for a total of 20 sets of tests. The flow of porous manifolds under different working conditions were observed and recorded. Through the dimensional analysis of the relational function formula of the geotextile filter layer to the flow of the porous manifold, regression analysis was performed to obtain the relationship expression between the parameters of the geotextile filter layer and the flow of the porous manifold, and the calculated sink flow was compared with the test value has a small error and high accuracy, which can be used to guide the actual project; when the parameters of the porous pipe were fixed, the confluence of the porous pipe under the geotextile filter layer was related to the surface density and the number of layers of the geotextile. The analysis of the test data shows that: when the geotextile filter layer density is constant, the water volume of the porous manifold decreases with the increase of the number of geotextile layers, and the rate decreases; when the number of geotextile layers is constant, the water vo-lume of the porous manifold increases with the surface As the density increases and decreases, a reasonable selection of the surface density and number of layers of geotextiles in actual engineering can achieve better technical and economic effects.

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2022 Vol. 40 (6): 576-581 [Abstract] ( 39 ) [HTML 1KB] [ PDF 1914KB] ( 400 )
582 Experimental study on floating objects being intercepted by and passing trash racks in pumping station
QIU Baoyun*,LIU Di,YUAN Lianchong,ZHAO Tong
Trash racks shall be set in the pump station before water inflow to intercept large volume floating objects, so as to avoid flow, efficiency reduction and motor overload caused by water pump entanglement. However, in order to reduce the head loss of sewage interception and the amount of sewage removal, small floating objects are allowed to pass through the pump through the grid. If a single floa-ting object in front of the trash rack is intercepted by the trash rack, the interception probability of subsequent small-size floating objects being intercepted will increase. In order to master the characteristics of floats being intercepted by and passing the trash rack, the movement of typical floats in water flow was observed by experimental methods, and the conditions and general laws of floats passing and being intercepted by trash racks were explored. The investigation results show that the probability of floats passing through the trash racks is related to the grid spacing, the size and character of the floats and flow velocity. The probability of floating objects passing through the racks of floats decreases with the increase of object-spacing ratio δ(the ratio of the float length to the space between the rack bars). When the distance ratio δ increases to the critical value δc, the probability curve of floating objects passing through the racks tends to be horizontal. For the floats objects with certain type and size, the probability of passing through the racks can be reduced by reducing the spacing between trash rack bars under the condition that the floats which pass through the racks could pass through the pump impeller. However, when δ reaches the critical value δ =δc, increasing the object-spacing ratio δ by increasing the rack bar density has little effect on improving the probability of float interception, on the contrary, it will increase the cost and hydraulic loss of the trash racks. The research results of this paper are of great significance for improving the design and operation management of trash racks and trash cleaning machine.

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2022 Vol. 40 (6): 582-587 [Abstract] ( 43 ) [HTML 1KB] [ PDF 4100KB] ( 413 )
588 Effect of nozzle shape on water-jet propeller propulsion performance
KONG Dongmei,PAN Zhongyong*,ZONG Ping
To explore different water-jet propulsion performance of nozzle shape, take an axial hydraulic propeller as the research object, the computational fluid dynamics method for three different shapes(planar, convex and concave)nozzle jet propeller is used for unsteady numerical simulation of the contrast analysis of the different internal flow characteristics and hydraulic propeller thrust nozzle shape performance at the rated speed and high speed, so as to find the of nozzle shape of optimal thrust performance. The calculation results show that when the impeller speed is constantly changing, the thrust performance of the planar nozzle is always greater than that of the water spray thruster of the other two shape nozzles. Among them, at high speeds, the cavitation will affect the functional force of the impeller, thereby reducing the thrust performance of the water-jet thruster. At the rated speed, the thrust performance of the planar and concave nozzles is better, but the maximum axial velocity distribution of the planar nozzle is more; at the high speed, the planar nozzle is minimally affected by the cavitation and can continuously provide stable power. The applicability of different nozzle shapes to the water spray thruster at different speeds and the water jet propulsion efficiency are revealed, which provides a certain theoretical basis for the performance optimization and design of the water jet thruster.

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2022 Vol. 40 (6): 588-595 [Abstract] ( 41 ) [HTML 1KB] [ PDF 3450KB] ( 447 )
596 Water hammer of gas-liquid two-phase flow shutoff valve in pipe network
YANG Ruihu,WANG Tong,SHANG Yujun,JIN Zhaogui,ZHANG Miao,WANG Wei,JU Cai,HAN Dapeng,
For simulation study on pipeline gas-liquid two-phase flow valve water hammer, after simplifying the internal gas-liquid two-phase flow pattern of the water supply network, by the C++ language water hammer analysis software, taking water supply engineering tree pipe network in Lu′an, Anhui province as an example, the end valve closing water hammer calculation model was first established, then the end of valve water hammers of different combinations were simulated and calculated.The calculation results show that if the water hammer produces the end valve closing hammer in the water supply pipe, the water hammer wave will spread to the adjacent main pipe and other connected trunk pipes.When the valve of the pipe network is closed, the pressure of the valve water hammer is more than 4.5 times, so the valve water hammer is extremely harmful to the water supply works. At the end, the water hammer protection measure of ″frequency-frequency hammer control flow control valve + box two-way pressure regulating valve + ordinary exhaust valve + constant speed buffer exhaust valve″ is proposed, and its prevention effect on the end valve closing water hammer is excellent.

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2022 Vol. 40 (6): 596-602 [Abstract] ( 40 ) [HTML 1KB] [ PDF 3426KB] ( 465 )
603 Vertical stratified simulation of chlorophyll content of summer maize based on PROSAIL model
WANG Shengfeng,XU Yaze,PENG Zhigong*,WEI Zheng,ZHANG Baozhong,CAI Jiabing,WANG Feiyu,MOU Yanwen
Simulation research on crop vertical layered chlorophyll monitoring was made to provide ba-sic data support for precision fertilization, irrigation and pest control. Summer maize chlorophyll and spectral reflection monitoring tests were carried out at different nitrogen application levels from 2019 to 2020, and the vertical stratified law of summer maize chlorophyll content was simulated. The results show that the chlorophyll content of summer maize shows a lateral bell shape as the canopy depth increases;the reflectance that the most sensitive band of chlorophyll is 699-722 nm was used to construct the summer maize chlorophyll simulation cost function, realizing the vertical stratification simulation of chlorophyll content in summer maize based on PROSAIL. Based on the comprehensive analysis of the estimation accuracy of chlorophyll in each layer at different growth stages, the simulation effect of vertical stratification of chlorophyll in summer maize was further clarified on the basis of controlling the re-lative error RE of average chlorophyll simulation within 45%, that is, the determinant coefficient R2 of the first layer of leaves during the tasseling and filling stage and the other layers in the whole fertility simulation is in the range of 0.114 5-0.799 3, the root mean square error RMSE is in the range of 2.41-12.13 μg/cm2 and the relative error RE is in the range of 9.67%-98.22%. The relevant research results can provide theoretical and technical support for the vertical stratified simulation application of crop chlorophyll.

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2022 Vol. 40 (6): 603-610 [Abstract] ( 38 ) [HTML 1KB] [ PDF 1991KB] ( 612 )
611 Optimization and experimental study on structural parameters of biological cells
LI Pengcheng,SU Yongjun,JIA Yue,HAO Fang*
The structural configuration and parameter selection of biological cells were studied to reveal its effect on rainwater storage and purification in central Shandong. Four representative factors of plant species, soil configuration, filter layer and particle size of filter layer were selected, three levels were set for the selected factors, 9 groups of test schemes were set through outdoor orthogonal test, and the corresponding test index parameters of storage and purification effects were analyzed by range analysis method, Using the TOPSIS multi-objective analysis and decision-making method, the comprehensive indexes were obtained, the significant factors were determined, and the scheme was provi-ded for the structural configuration. In terms of rainwater storage and detention, the average rainwater storage rate was 56.08%, the average runoff production start time and average peak time were 103.94 min and 146.50 min respectively, which were positively correlated. In terms of water purification effect, the overall effect on the reduction of suspended solids(SS)and total phosphorus was obvious, the average reduction rates were 62.89% and 70.86% respectively, and the effect on the reduction of COD was obvious, with an average reduction rate of 48.03%, The effect of total nitrogen reduction was relatively weak, and the average reduction rate was 42.56%. Construct the classification method of biological cells. For the selected biological detention tank with weak storage and strong filtration, the selection of filter layer had the most significant influence, the particle size of filter layer took the second place, and the plant species and soil configuration had no significant influence. The best structural configuration was that the plant species was Pennisetum. The soil configuration was 40% cultivated soil, 30% peat soil and 30% sandy soil. The filler was 30cm thick quartz sand in the upper layer and 20cm thick zeolite in the lower layer. The particle size of the filter layer should be small.

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2022 Vol. 40 (6): 611-617 [Abstract] ( 27 ) [HTML 1KB] [ PDF 2208KB] ( 498 )
618 Research and application on advance of soil conditioners of primary degraded soils in China
ZHAO Peng,HUANG Zhanbin*,REN Zhongxiu,YU Jiayi
Based on the main types and distribution of degraded soil in China, different amelioration techniques of degraded soil were compared and analyzed. Combined with the research situation at home and abroad and the raw materials and classification of soil amendments, the main functional effects of soil amendments on soil and crops were summarized. The research results of soil amendments in acidified soil, saline-alkali soil and heavy metal contaminated soil were expounded, and the problems existed in the application of soil amendments in different types of degraded soil were put forward. Finally, the main problems in soil conditioner research and development and application process were further explored. Combined with the green and sustainable development orientation, pointed out that strengthening the application basic research, the research and development of new and environmental protection and low-cost, the application evaluation, the application standard establishment, the certification ma-nagement of soil amendments and the comprehensive management of degraded soil is the develop-ment tendency of soil amendments research and application.

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2022 Vol. 40 (6): 618-625 [Abstract] ( 38 ) [HTML 1KB] [ PDF 1370KB] ( 652 )
626 Effects of water and fertilizer control on soil phosphorus content of Panax notoginseng under micro-sprinkler irrigation
ZHENG Yang,TUO Yunfei*,YANG Cuiping,WANG Qian,WANG Zhaoyi,XIANG Ping,YANG Qiliang
Through three orthogonal tests at water control levels and four at fertilizer control levels, an experimental study was carried out on the migration distribution and reserve characteristics of total phosphorus and available phosphorus under micro-sprinkler irrigation in Panicum under water control and fertilizer control in the typical planting area of Panicum in Dalishu Village, Luxi County, Yunnan province from 2017 to 2019. The results showed that the total phosphorus content with Panax notoginseng as the center of different irrigation amount decreased gradually in the horizontal direction and the increase of soil depth. The maximum value in the horizontal direction ranged from 0 to 10cm, and the maximum value in the soil depth ranged from 0 to 20 cm.The available phosphorus decreased first and then increased in the horizontal direction and soil depth, and the maximum appeared in the range of 0-20 cm in the horizontal direction and soil depth. With Panax notoginseng plants as the center, total phosphorus and available phosphorus at different fertilization rates decreased first and then increased in the horizontal direction and soil depth. The maximum value of total phosphorus and available phospho-rus in the horizontal direction and soil depth ranged from 0 to 10 cm. The distribution uniformity coefficients of total phosphorus and available phosphorus at different irrigation volumes decreased first and then increased with the increase of irrigation volume. The distribution uniformity coefficients of total phosphorus and available phosphorus at W3F2 treatment were the lowest, 46.77% and 62.70%, respectively; the skewness coefficients of total phosphorus at CK treatment were negative; the skewness coefficients of total phosphorus and available phosphorus at other treatments were positive.The distribution uniformity coefficients of total phosphorus and available phosphorus at different fertilizer rates decreased first and then increased with the increase of fertilizer rates. The distribution uniformity coefficient of total phosphorus at W2F3 treatment was the lowest, which was 46.83%, and that at W2F4 treatment was the lowest, which was 68.68%. The skewness coefficient of available phosphorus at W2F1 treatment was negative, and the skewness coefficients of total phosphorus and available phosphorus at other treatments were both positive.The reserves of total phosphorus and available phosphorus at different irrigation volumes were the largest at 0-20 cm on the surface of soil. The reserves of total phosphorus and available phosphorus decreased with the increase of soil depth and increased with the increase of irrigation volume. Total phosphorus and available phosphorus reserves at different fertilizer rates increased first and then decreased with the increase of fertilizer rates, and the average value of total phosphorus and available phosphorus reserves at W2F3 treatment was the highest.This study provided technical support for the efficient utilization and regulation of soil water and fertilizer in Panax notoginseng and had important guiding significance for the high-yield and high-quality cultivation of Panax notoginseng.

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2022 Vol. 40 (6): 626-634 [Abstract] ( 60 ) [HTML 1KB] [ PDF 2419KB] ( 482 )
635 Detection of Malathion by nanochannel aptamer sensor
DONG Xiaoya*,WANG Xvrui,HUANG Huajie,WANG Xuean
Accurate and rapid detection of pesticide residues in water is crucial to water safety. Based on the current rectification phenomenon of nanochannels, and combined with the characteristics of aptamers that specifically binding to the target, an electrochemical aptamer sensor was constructed to realize the detection of malathion(Mal). The Mal aptamer 1(Apt-1)was modified into the gold-coated nanopipette lumen through gold-sulfur bonds, and the specific binding of Mal to Apt-1 and apta-mer 2(Apt-2)was used to change the interior of the nanochannel. The characteristics of charge density enable the quantitative detection of Mal. Scanning electron microscopy(SEM)and circular dichroism(CD)were used to characterize the nanopipettes and the inside of the nanochannel. The experimental parameters such as the modification concentration of Apt-1, the concentration of Apt-2, and the pH of the incubation solution and the incubation time were optimized. Under the optimum experimental conditions, the logarithm of Mal concentration is linear with the response current signal of the sensor, and linear range of Mal detection range of the sensor is 1.0×10-8-1.0×10-6 mol/L, and the limit of detection(LOD)was 3.33×10-9 mol/L. The stability of the aptamer sensor and the selectivity of Mal detection were investigated. The sensor can be used for the analysis of Mal in water samples, and the results obtained are basically consistent with those obtained by gas chromatography(GC).

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2022 Vol. 40 (6): 635-641 [Abstract] ( 37 ) [HTML 1KB] [ PDF 2579KB] ( 472 )
642 Optimized layout of pressure monitoring points in water supply network based on FCM clustering and leakage events simulation
XU Zhiqiang,LIU QifengSymbolj@@,LIU Jiafeng,SHAN Liming,PEI Wensi
In order to improve the reliability of pressure monitoring points in the water supply network, a layout method of pressure monitoring points combining fuzzy C-means(FCM)clustering with the maximum perceived number of leakage events is proposed based on a District Metered Area(DMA)in a town in northern China. Firstly, the FCM algorithm was used to cluster all nodes based on the nodes pressure sensitivity coefficient matrix of water quantity change in the pipe network, and the alternative pressure monitoring points in each subclass were preselected. Then, the possible leakage events were simulated randomly to test the perception of the alternative monitoring points with different optimized combinations for the pressure changes caused by the leakage events, and the optimal monitoring points′ layout scheme was determined. The simulation results of this case show that more than 96.36% of the leakages were detected with at least three monitoring points on the premise of ensuring that at least two monitoring points can perceive the same leakage event. This method can improve the monitoring reliability and at the same time save the cost.

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2022 Vol. 40 (6): 642-648 [Abstract] ( 34 ) [HTML 1KB] [ PDF 1463KB] ( 405 )
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