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柱塞式注肥泵内流动瞬态特性数值模拟与试验

农业工程学报 2024年第16期40卷 75-83页

作者：康邵暄黎耀军严海军王晶晶中国农业大学农业水资源高效利用全国重点实验室北京100083 中国农业大学北京市供水管网系统安全与节能工程技术研究中心北京100083

柱塞式注肥泵是水肥一体化系统肥液注入的关键设备,为探明柱塞往复运动过程中柱塞式注肥泵的内部流动特征及外特性,该研究基于RNG k-ε湍流模型和动网格技术,构建注肥泵内流动三维动态数值模拟模型,对不同柱塞行程比和往复频率工况的泵... 详细信息

柱塞式注肥泵是水肥一体化系统肥液注入的关键设备,为探明柱塞往复运动过程中柱塞式注肥泵的内部流动特征及外特性,该研究基于RNG k-ε湍流模型和动网格技术,构建注肥泵内流动三维动态数值模拟模型,对不同柱塞行程比和往复频率工况的泵内瞬态流动进行非定常数值模拟,预测柱塞泵外特性并分析额定工况的泵内流场特征,通过与试验数据及理论计算结果的对比,验证数值模拟模型的可靠性。结果表明:不同行程下模拟所得的时间平均流量与试验结果最大相对误差为3.58%,数值模拟所得瞬时流量大小及变化趋势与理论计算结果吻合良好,最大相对误差为3.17%;泵排出、吸入过程的初始阶段,分别存在进、出口单向阀阀芯闭合滞后现象,伴随形成回流;受阀芯闭合滞后导致的回流影响,注肥泵瞬时流量存在突变,其突变时刻与阀芯闭合时刻一致;注肥泵平均流量与柱塞行程和往复频率均呈线性正相关,泵容积系数随柱塞行程的减小而降低,但随柱塞往复频率的变化不明显,变频调控可更准确调节注肥泵流量,是水肥一体化系统中注肥流量调节的优选方式。研究结果可为柱塞式注肥泵设计与运行调控提供依据。

关键词：泵试验柱塞式注肥泵单向阀动网格数值模拟

Mobile bed thickness in skewed asymmetric oscillatory sheet flows

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Acta Mechanica Sinica 2018年第2期34卷 257-265页

作者： Xin Chen Yong li fujun {2. beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System China Agricultural University Tianjin Centre China Geological Survey

A new instantaneous mobile bed thickness model is presented for sediment transport in skewed asymmetric oscillatory sheet flows. The proposed model includes a basic bed load part and a suspended load part related to the Shields parameter, and takes into account the effects of mass conservation, phase-lag, and asymmetric boundary layer development, which are important in skewed asymmetric flows but usually absent in classical models. The proposed model is validated by erosion depth and sheet flow layer thickness data in both steady and unsteady flows, and applied to a new instantaneous sediment transport rate formula. With higher accuracy than classical empirical models in steady flows, the new formula can also be used for instantaneous sediment transport rate prediction in skewed asymmetric oscillatory sheet flows.

关键词： Mobile bed thickness Phase-lag Sediment transport Sheet flow Skewed asymmetric oscillatory flow

Experimental Investigation of Flow Patterns in a Pump Intake with Different CWL(Critical Water Level)and Back-Wall Clearance

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Journal of Thermal Science 2021年第6期30卷 2150-2163页

作者： GUO Miao TANG Xuelin li Xiaoqin {2. fujun College of Water Resources and Civil Engineering China Agricultural UniversityBeijing 100083China beijing Engineering Research Centre of Safety and Energy Saving Technology for Water Supply Network System China Agricultural UniversityBeijing 100083China

In this study,influence of back-wall clearance,CWL(Critical Water Level)and air content in water on flow patterns in a pump intake has been investigated experimentally and theoretically for different *** statistical data show that CWL for a two-phase flow is lower than that in the case of a single-phase flow at a relatively low flow rate,and as the flow rate increases,this trend turns out to be completely *** experimental data obtained under conditions of subcritical,critical and supercritical flow rates have revealed that the larger the back-wall clearance is,the more vortices exist and the higher the vorticity of free-surface vortices *** the smallest back-wall clearance,the flow coming through the inlet occupies most space under the pipe bell,and both this flow and the inflow coming from the back wall are asymmetric relative to a certain vertical line other than the *** the larger and the largest back-wall clearances,the flows coming from the inlet and from the back wall are almost symmetrical relative to the vertical axis of the pipe *** velocity distributions on two PIV measurement lines for different back-wall clearance magnitudes indicate that the smallest back-wall clearance influences the flow around the pipe bell.

关键词： Critical Water Level(CWL) back-wall clearance air content in water pump intake

A general alternate loading technique and its applications in the inverse designs of centrifugal and mixed-flow pump impellers

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Science china(Technological Sciences) 2021年第4期64卷 898-918页

作者： wang ChaoYue wang {2. AN DongSen YAO ZhiFeng XIAO RuoFu LU li HE Chenglian ZOU ZhiChao College of Water Resources and Civil Engineering China Agricultural UniversityBeijing 100083China beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System Beijing 100083China china Institute of Water Resources and Hydropower Research Beijing 100038China china Water Resources Beifang Investigation Design and Research Co.Ltd.Tianjin 300222China

For the inverse designs of centrifugal and mixed-flow pump impellers,clarifying the generation process of secondary flows and putting forward corresponding suppression measures is an important approach to improve the impeller *** this paper,to provide a better qualitative insight into the generation mechanism of secondary flows in the impeller,a simple kinematic equation is derived based on the ideal assumptions,which indicates that the potential rothalpy gradient(PRG)is the most important dynamic source that actively induces secondary vortical *** by the natural adverse PRG on the S1 and S2.stream surfaces,two typical secondary flows,H-S and P-S secondary flows,are clearly *** specially suppress these typical secondary flows,a general alternate loading technique(GALT)is proposed,aiming to adjust the real blade loadingδp to control the PRG *** the blade fore part,theδp on the hub streamline should be slowly increased to avoid breakneck growth of the potential rothalpy to reduce adverse streamwise PRG on the S2.*** the blade middle part,theδp should be moderately decreased to reduce adverse streamwise PRG on the S1 *** the blade aft part,the difference in theδp between the shroud and hub streamlines should be decreased faster to control the exit *** applying the GALT to the impeller designs of three typical pump types in hydraulic engineering,the organizational effect of the PRG on fundamental flow structures is *** GALT can effectively control the PRG distributions and suppress the secondary flows,thereby widening the pump’s high-efficiency zone,improving flow uniformity and suppressing pressure *** with the current Z-G method and the ALT,the GALT can meet the requirements of"de-experience"better,thereby enabling the designers to obtain good products explicitly and quickly.

关键词： alternate loading technique inverse design centrifugal pump mixed-flow pump impeller potential rothalpy gradient

Applications of Three-Dimensional LBM-LES Combined Model for Pump Intakes

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Communications in Computational Physics 2018年第6期24卷 104-122页

作者： Miao Guo Xuelin Tang Yanwen Su Xiaoqin li {2. wang College of Water Resources and Civil Engineering China Agricultural UniversityBeijing 100083China beijing Engineering Research Centre of Safety and Energy Saving Technology for Water SupplyNetwork System China AgriculturalUniversityBeijing 100083China

Lattice Boltzmannmodel(LBM)in conjunction with an accurate Large Eddy Simulation(LES)technology was proposed to simulate various vortical structures and their evolutions in open pump *** strain rate tensor in the LES model is locally calculated by means of non-equilibrium moments based on Chapman-Enskog expansion,and bounce-back scheme was used for non-slip condition on solid walls and reflection scheme for free *** presentedmodel was applied to investigate free-surface and wall-attached vortices for different water levels and flow *** vortex position,shapes and vorticities were predicted successfully under three flowing cases(*** water level(CWL),lower water level,lower flow rate),and the numerical velocity and streamline distribution were analyzed *** CWL based on Froude number considering open channel flows,the shape and the location of various dynamic vortices were *** to the experimental results of CWL,more vortices were predicted for lower water level,and less vortices were observed for lower flow *** predicted velocities and vortex locations are in good agreement with the experimental of a small physical *** comparisons demonstrated the feasibility and stability of above-mentioned model and numerical method in predicting vortex flows inside open pump intakes.

关键词： Lattice Boltzmannmodel Large Eddy Simulation free-surface vortices wall-attached vortices open pump intakes

滇东典型煤矿区土壤重金属生态风险及来源解析

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中国地质 2024年第1期51卷 327-340页

作者：姜昕马一奇涂春霖黄安胡要君叶雷和成忠李世玉中国地质调查局昆明自然资源综合调查中心自然资源部自然生态系统碳汇工程技术创新中心云南昆明650100 中国地质大学(北京)水资源与环境学院北京100083 云南大学生态与环境学院云南昆明650504

【研究目的】研究区地处滇东重要煤炭和农业产区,弄清煤矿区土壤重金属空间分布特征、潜在生态风险和污染来源,对煤矿区生态环境保护治理和确保农业安全具有重要现实意义。【研究方法】基于网格布点法于2.2.年6月在典型煤矿区采集土壤样... 详细信息

【研究目的】研究区地处滇东重要煤炭和农业产区,弄清煤矿区土壤重金属空间分布特征、潜在生态风险和污染来源,对煤矿区生态环境保护治理和确保农业安全具有重要现实意义。【研究方法】基于网格布点法于2.2.年6月在典型煤矿区采集土壤样品497件,分析了土壤pH、SOM、As、Cd、Cr、Cu、Hg、Ni、Pb和Zn,运用污染负荷指数法和潜在生态风险指数法对重金属污染状况和潜在生态风险进行评价,通过主成分分析和正定矩阵因子分析(PMF)模型分析了重金属潜在来源。【研究结果】土壤pH平均值为5.39,以酸性为主,SOM含量平均值是云南省土壤背景值的1.2.倍,Cr、Cu、Cd、Ni、Zn和Hg含量平均值和中位数均超过云南省土壤背景值,绝大部分采样点Cd、Cu、Cr、Ni含量超过风险筛选值,分别占94.97%、93.96%、91.35%、79.2.%,少部分采样点As、Cd含量超过管制值,分别占0.2.%、1.41%。污染负荷指数法评价结果显示,研究区整体呈现轻微污染。潜在生态风险指数法评价结果显示,研究区整体呈现中等风险。主成分分析和PMF模型解析结果显示,研究区土壤重金属主要来源于地质背景,其次为农业活动和大气沉降。【结论】煤矿区土壤中Cd、Hg潜在生态风险较高,土壤重金属主要来源于地质背景,其次是农业活动和大气沉降,建议加强相关污染土地的监测和管理,减少农家肥不合理施用,强化煤炭工业污染排放监管。

关键词：煤矿区地质调查工程土壤重金属污染生态风险评价污染来源

中国绿色证券与传统金融市场风险传染机制研究

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管理工程学报 2023年第6期37卷 77-93页

作者：高扬李杨洋王耀君北京工业大学经济与管理学院北京100124 中国农业大学信息与电气工程学院北京100083

随着我国绿色证券市场规模的不断扩大、金融衍生品种类的不断增多及其资金来源的复杂化,绿色证券市场的风险可控性逐渐降低,其与传统金融市场的融合过程中很可能会积聚风险并引发风险传染。本文重构了金融系统研究框架,探究了绿色债券... 详细信息

随着我国绿色证券市场规模的不断扩大、金融衍生品种类的不断增多及其资金来源的复杂化,绿色证券市场的风险可控性逐渐降低,其与传统金融市场的融合过程中很可能会积聚风险并引发风险传染。本文重构了金融系统研究框架,探究了绿色债券、绿色股票与依行业划分的完整金融市场间的风险传染机制。通过分别构建R-藤Copula模型和混频有向加权复杂网络,探究了我国绿色证券市场与传统金融市场在系统层面的风险传染路径,进一步完善了在中国的特定市场条件下风险传递机制的理论框架。此外,通过对原油价格暴涨、中美贸易战/定向降准以及新冠疫情三阶段金融事件进行对比研究,发现金融事件会通过提升跨市场风险传染水平,经过“风险产生→交叉传染→再交叉传染”的过程使金融系统风险联通性整体上升。此外金融事件的发生会引起使得高频溢出水平显著上升,中频溢出和低频溢出会向高频溢出转化。研究结果不仅有助于监管者维护绿色证券市场的稳定与健康发展,完善绿色证券的风险控制体系,同时可以促进绿色证券投资者规避投资风险和优化资产配置。

关键词：绿色证券市场风险传染 R-藤Copula 溢出指数混频复杂网络

基于双流体模型的尊村泵站双吸离心泵泥沙磨损

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科学通报 2019年第36期64卷 3856-3866页

作者：李嘉兴王福军陈鑫中国农业大学水利与土木工程学院北京100083 中国农业大学北京市供水管网系统安全与节能工程技术研究中心北京100083

黄河尊村二级泵站的高效稳定运行一直都受水泵的泥沙磨损问题制约,其影响因素包括过泵水流的泥沙体积分数和泥沙粒径.采用双流体模型对尊村二级泵站的双吸离心泵内水沙两相流进行数值模拟,在模型中考虑了颗粒动态尺度对颗粒湍动扩散系... 详细信息

黄河尊村二级泵站的高效稳定运行一直都受水泵的泥沙磨损问题制约,其影响因素包括过泵水流的泥沙体积分数和泥沙粒径.采用双流体模型对尊村二级泵站的双吸离心泵内水沙两相流进行数值模拟,在模型中考虑了颗粒动态尺度对颗粒湍动扩散系数的影响,以及颗粒的惯性和湍动对相间阻力的影响;采用Oka磨损模型计算了泵内泥沙磨损.模拟了由4种典型泥沙体积分数和4种典型泥沙粒径组合成的16种入口泥沙工况,在此基础上研究了入口泥沙体积分数和泥沙粒径对泵内磨损的影响规律.结果表明,不同泥沙条件下该泵发生严重磨损的区域主要位于叶片和蜗壳,其中叶片中后部和蜗壳隔舌的磨损最为严重.随着入口泥沙体积分数增加,叶片和蜗壳的磨损速率呈线性趋势上升;随着泥沙粒径的增加,叶片和蜗壳的磨损速率呈现小幅度增加,且磨损速率增长斜率随粒径增加逐渐放缓.根据该结果,可采取措施降低过泵水流中的泥沙体积分数和泥沙粒径以缓解双吸离心泵内的泥沙磨损.

关键词：双吸离心泵泥沙磨损双流体模型泥沙粒径泥沙体积分数

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摇臂式喷头喷嘴结构改进及水力性能试验研究

水利学报 2019年第4期50卷 488-496页

作者：王子君惠鑫黎耀军严海军中国农业大学水利与土木工程学院北京100083 势加透博(北京)科技有限公司北京100012

为了降低摇臂式喷头在工程应用中的运行成本、提高喷灌质量,本文针对8034D摇臂式喷头主、副喷嘴结构进行了优化改进,并研究了喷嘴结构改进后对喷头流量、径向水量分布和组合喷灌均匀度的影响。结果表明,主喷嘴内腔锥度角对喷头流量的影... 详细信息

为了降低摇臂式喷头在工程应用中的运行成本、提高喷灌质量,本文针对8034D摇臂式喷头主、副喷嘴结构进行了优化改进,并研究了喷嘴结构改进后对喷头流量、径向水量分布和组合喷灌均匀度的影响。结果表明,主喷嘴内腔锥度角对喷头流量的影响呈显著水平,内腔锥度角越大,喷头流量越小;当工作压力相同时,改进副喷嘴结构对喷头流量的影响不大。随着测点与喷头水平距离的逐渐增加,不同内腔锥度角和圆柱段长度下的径向喷灌强度均呈递减趋势。组合2.1 mm#54°主喷嘴与改进后副喷嘴组合)在4种组合方式中的喷灌均匀性较好,其在喷头正方形布置下7种组合间距(12.m×12.m～18 m×18 m)时的平均喷灌均匀系数为87.8%,其中17 m×17 m时的喷灌均匀系数峰值达到89.3%。综合考虑喷灌质量和经济性两方面,在实际工程设计时,建议8034D摇臂式喷头主、副喷嘴的组合方式优先选用组合2.喷头工作压力设置为2.0 kPa,且组合间距以17 m×17 m为宜。

关键词：摇臂式喷头喷嘴结构改进喷头流量径向水量分布组合喷灌均匀度