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1.
A combination of the rainfall-runoff module of the Xin’anjiang model, the Muskingum routing method, the water stage simulating hydrologic method, the diffusion wave nonlinear water stage method, and the real-time error correction method is applied to the real-time flood forecasting and regulation of the Huai River with flood diversion and retarding areas. The Xin’anjiang model is used to forecast the flood discharge hydrograph of the upstream and tributary. The flood routing of the main channel and flood diversion areas is based on the Muskingum method. The water stage of the downstream boundary condition is calculated with the water stage simulating hydrologic method and the water stages of each cross section are calculated from downstream to upstream with the diffusion wave nonlinear water stage method. The input flood discharge hydrograph from the main channel to the flood diversion area is estimated with the fixed split ratio of the main channel discharge. The flood flow inside the flood retarding area is calculated as a reservoir with the water balance method. The faded-memory forgetting factor least square of error series is used as the real-time error correction method for forecasting discharge and water stage. As an example, the combined models were applied to flood forecasting and regulation of the upper reaches of the Huai River above Lutaizi during the 2007 flood season. The forecast achieves a high accuracy and the results show that the combined models provide a scientific way of flood forecasting and regulation for a complex watershed with flood diversion and retarding areas.  相似文献   

2.
The surge tank plays an important role in ensuring the stability of a water flow standard device. To study the influence of the structure and the working conditions on the regulator performance of a surge tank, a three-dimensional model, including a surge tank, the pipeline and the water tank is built, and the VOF model in the Fluent software is used to simulate the two-phase pulsatile flow in the surge tank. The inlet flow pulsation is defined by the User Defined Functions (UDF), and the outlet flow is set to be a free jet. By calculating the flow fluctuation coefficient of the variation uader different flow conditions, the influences of the pulse frequency, the initial water level height and the baffle plate structure on the flow stability are analyzed. It is shown that the surge tank has a good attenuation effect on high-frequency pulsations, there is an optimal initial water level to suppress the fluctuations, the round holes of the baffle should ensure a certain circulation area with the bore diameter small enough to have the necessary damping effect.  相似文献   

3.
A three dimensional numerical model based on the Reynolds equations is presented that can be used to predictthe surface water flow in open channels.The model uses a computational mesh that conforms to the free water sur-face and the bottom of the channel so that the accuracy of boundary condition application,code complexity,and e-conomy could be enhanced.The k-ε turbulence model is used to estimate the eddy viscosity coefficient.Instead ofusing the“rigid-lid”approximation a 2-D equation derived from integrating the continuity equation over the totaldepth is adopted to determine the elevation of the free water surface.A new algorithm is presented based on theconventional SIMPLE procedure.The block correction technique is employed to enhance rate of convergence.The model presented is applied to a bottom discharge into a rectangular straight channel for three dimensionalphenomena to obtain the free water surface configuration,velocities and pressure.The computed results are ingood agreement with the previous experimental values.  相似文献   

4.
This paper introduces the hydrodynamics theory related to water wave pump. Water wave pump is a new type pump, which uses the particular quality of water wave and re-divides the inflow energy to increase the pressure of one part of the inflow water with the rest water flowing away freely. The research and development of such a pump is of importance and significant value and profitable social interest in that it can fully utilize the residual energy of natural source in industrial and civil water circle systems. Through hydrodynamies research and calculation, a series of valid design parameters were obtained and the predicted results achieved.  相似文献   

5.
A combined method is proposed to determine the water entry acceleration at a low impact velocity through image processing. The procedure includes: (1) a sequence of images for water impact are recorded by a high speed camera, (2) the sub-pixel image processing method is employed to calculate the displacement with an accuracy on the "sub-pixel" level, (3) the acceleration of the object is acquired by differentiating the displacement twice and with results being further filtered by a carefully designed low-pass Butterworth filter. A theoretically based analysis is conducted for designing the parameters of the low-pass filters. It is shown that the water entry can be regarded as a procedure with a slowly changing velocity. The method is validated with the standard sinusoidal motion and the water entry of a sphere. This approach could be considered as an auxiliary method during the early-stage study of the water entry, and it could be further applied to some complicated circumstances, like the water entry of spinning spheres.  相似文献   

6.
A NOVEL 3-D MODEL FOR THE WATER CRESTING IN HORIZONTAL WELLS   总被引:1,自引:1,他引:0  
In the presence of bottom water, a drop in the reservoir pressure due to fluid production causes the aquifer water to expand and to flow into the reservoir. Therefore, hydrocarbon production from a well is limited by the critical flow rate. The main purpose of this study is to investigate the breakthrough time and the critical rate by using a novel 3-D horizontal well model. Based on the hypothesis that the horizontal well is located in any position of a circular reservoir with no-flow boundary on the top of the reservoir and constant pressure boundary at the bottom, the horizontal well has been regarded as an infinite conductivity line sink and then a 3-D steady-state flow model of the horizontal well is set up. A point sink pressure solution can be obtained with the Fourier transform. The result of the pressure distribution of the uniform flux horizontal well can be presented by means of the principle of superposition. According to the stable water cresting theory, this study confirms the stable height of water cresting and the critical rate. Meanwhile, it can re-confirm the breakthrough time at a specific rate. The output of a comparison between this 3-D model and the reservoir numerical simulator (Eclipse) shows the method presented here can be applied to investigate the behavior of a water cresting and to predict the breakthrough time at the bottom water driver reservoir.  相似文献   

7.
8.
Imbalance arises when the Roe’s method is directly applied in the shallow water simulation.The reasons are different for the continuity equation and the momentum equations.Based on the Roe’s method,a partial surface method is proposed for a perfect balance for the continuity equation.In order to generate a mathematically hyperbolic formulation,the momentum equations are split,which causes incompatibility in the calculation of the momentum equations.In this article a numerical approach named the Slop Flux Method(SFM)is proposed to balance the source terms and the flux gradient based on the finite volume method.The method is first applied to shallow water equations.The model is verified by analytical results of classical test cases with good agreement.Finally the method is applied to a steady flow simulation over a practical complicated topography and the result shows good balance and conservation.  相似文献   

9.
The Middle Route Project for South-to-North Water Transfer, which consists of a long artificial open channel and various hydraulic constructions, is a big water conveyance system. A numerical modeling of water conveyance in the ice period for such large-scale and long distance water transfer project is developed based on the integration of a river ice model and an unsteady flow model with complex inner boundaries. A simplified method to obtain the same flow discharge in the upstream and downstream of the structure by neglecting the storage effect is proposed for dealing with the inner boundaries. According to the measured and design data in winter-spring period, the whole ice process, which includes the formation of the ice cover, its development, the melting and the breaking up as well as the ice-water dynamic response during the gate operation for the middle route, is simulated. The ice characteristics and the water conveyance capacity are both analyzed and thus the hydraulic control conditions for a safety regulation are obtained. At last, the uncertainties of some parameters related to the ice model are discussed.  相似文献   

10.
Based on the established evaluation indicator system of urban water system, evaluation indicator data collected from six typical pilot sponge cities were analyzed using a coupling coordination model to empirically examine the development status of coupling coordination of the water system of different cities. The key indicators were identified through grey correlation analysis, and a vector auto regression model was established to investigate the mechanism, through which these key indicators impact the development of coupling coordination of the water system. The findings indicate that the water system of the six cities has progressed from serious or moderate incoordination to coordination after the construction of sponge cities, and “sponging” reconstruction had better short-term effectiveness in southern pilot cities, including Wuhan, Shenzhen, and Shanghai, compared to northern pilot cities, including Jinan and Beijing. Furthermore, the coupling coordination degree between the water ecology and water security subsystems is found to be the highest, while river regulation rate and drinking water compliance rate exert fluctuating effects, alternatively impeding or promoting the interrelation between the two sub-systems. By contrast, the coupling coordination degree between the water resources and water culture subsystems is the weakest, while the number of official platform publicity exerts a significant and sustained positive effect on the relationship between the two sub-systems. Additionally, there is a need for further enhancement of the coupling coordination degree between the water resources and water environment subsystems, and the increases of water consumption per 10 000 yuan of GDP and sewage treatment rate have significant promoting but short-lived effects on the coordination between the two sub-systems. © 2023, Editorial Board of Water Resources Protection. All rights reserved.  相似文献   

11.
滴灌灌水器迷宫式流道内部流体流动特性分析与试验研究   总被引:15,自引:0,他引:15  
李云开  杨培岭  任树梅  杨玲 《水利学报》2005,36(7):0886-0890
选取目前中国农业灌溉领域中最为典型的六种迷宫式流道滴灌管,利用精密读数显微镜与AutoCAD技术相结合的测量方式测定了流道几何参数,利用自行研制的灌水器水力性能测试平台测量了六种滴灌灌水器在不同压力条件下的自由出流流量,并研究了灌水器流道内部的流动特性。结果表明:低压运行对灌水器的水力性能有一定影响,但不显著;流道断面统计平均流速在0.08—0.90m/s之间;迷宫式流道内部流体流动的雷诺数R,为105—930,层流和紊流的流态转捩的临界雷诺数比常规尺度流道的值要小,低于255。  相似文献   

12.
圆柱型灌水器迷宫式流道内部流体流动分析与数值模拟   总被引:13,自引:1,他引:12  
要想设计出高性能的滴灌灌水器必须对其内部流动机理有一个全面的了解,迷宫式流道狭窄且边界极为复杂,原型试验在技术和经济上都比较困难,常规手段难以满足流场测试要求,基于计算流体动力学理论的数值仿真研究流道内部流体流动问题是一种行之有效的方法。通过对迷宫式流道内部流体流动特性的分析,构建了表征迷宫式流道内部流动的数学物理模型;对所选取的目前中国农业灌溉领域最为典型的三种圆柱型灌水器,借助FLUENT6.1CFD流场软件分析平台实现了流道内部流速分布、涡量分布、紊流强度分布等流动特性的可视化,为新型灌水器流道研制提供一定理论基础。  相似文献   

13.
侯鹏  肖洋  吴乃阳  王海军  马永久  李云开 《水利学报》2020,51(11):1372-1382
传统的黄河水沉淀-过滤系统存在沉沙池建设成本高、过滤器频繁反冲洗能耗高等问题,让更多的细颗粒泥沙随水流排出灌水器体外是解决黄河水滴灌系统灌水器堵塞的新思路,而摸清泥沙在黄河水滴灌系统内部的淤积特性以及灌水器结构-淤积泥沙特性-堵塞特性参数间的相关关系是探索其排沙能力的前提和基础。为此,本文在河套灌区开展了黄河水滴灌系统灌水器堵塞原位试验,系统分析了6种内镶贴片式灌水器内部细颗粒泥沙含量及粒径分布动态变化特征,探索了三者间的级联关系。结果表明:进入灌水器内部的泥沙99%以上可以排出体外,淤积在灌水器内部的泥沙以粉粒为主、砂粒次之、黏粒最少。随着灌水器堵塞加剧,内部淤积泥沙的黏粒、粉粒比例相对降低,而砂粒比例相对增加,泥沙进入灌水器后存在聚集等行为,使得灌水器内部淤积泥沙粒径明显高于毛管入口。泥沙比表面积淤积量、粉粒比例、砂粒比例、D50D95对黄河水滴灌系统Dra、克里斯琴森均匀系数CU影响显著(p<0.05),不同灌水器淤积泥沙粒径明显不同,D50与灌水器结构无量纲参数(流道宽深比W/D、面积长度比A1/2/L)及断面平均流速v显著(p<0.05)相关。本研究对引黄滴灌灌水器设计及灌溉系统过滤配置具有指导意义。  相似文献   

14.
滴头选型对玉米生长发育及产量的影响   总被引:2,自引:0,他引:2  
以分析滴头流量对玉米生长发育及其产量的影响为目标,在石河子科学观测实验站选择郑单958开展玉米膜下滴灌试验,选择四种内镶式滴头和一种迷宫式滴头,从出苗率、株高、叶面积指数、叶绿素含量、干物质、产量等方面分析滴头流量对玉米生长的影响。结果表明:一周后新疆大田作物普遍采用的迷宫式2.4 L/h出流量滴灌带(L5)和内镶式1.38 L/h出流量滴灌带(L4)出苗率较高,但内镶式3.0 L/h出流量滴灌带(L1)总出苗率最高;内镶式2.4 L/h出流量滴灌带(L2)株高最高,内镶式2.0 L/h出流量滴灌带(L3)叶面积指数最高,内镶式滴灌带处理的产量均高于迷宫式滴灌带。滴灌玉米拔节期、吐丝期和成熟期整株生物量均随着滴头流量减小而呈现单峰增长趋势;L2处理产量最高,较L1增产幅度为27.29%。本试验条件下,滴头流量2.038 L/h时滴灌玉米理论产量最高为15 377.66 kg/hm~2,建议玉米膜下滴灌滴头流量选择内镶式2.0~2.4 L/h之间的滴灌带。该试验结果对干旱区发展高效农业节水灌溉具有参考价值。  相似文献   

15.
通过多滴头小管径滴管系统灌水试验研究,评价流量与水头压力关系,进而进行灌水器的综合性能指标分析与评价。结果表明:在额定压力工作条件下,灌水器的制造偏差小于5%,等级为优等;灌水器的灌水均匀度大于95%,灌水均匀性良好;灌水器的水头损失比例为3%,损失比例较小,适宜于温室灌溉。  相似文献   

16.
杜泽金  潘少华  李蘅 《人民长江》2016,46(13):93-96
云南晓街河水库工程泄水建筑物采用堰式进口溢洪洞,进口布置开敞式溢流堰,泄槽段采用隧洞型式。由于泄水建筑物结构较为特殊,且上、下游水头差高达79 m,水力特性较为复杂。通过泄流能力、流态、沿程水面线等水力计算分析,并结合模型试验,分析了堰式进口溢洪洞的布置、结构、尺寸等设计要求及水力特性。验证结果表明,设计方案中的溢洪洞泄流能力满足工程要求且流态较好。可为类似工程设计提供一定参考。  相似文献   

17.
为了明确输水隧洞内的明满流水力瞬变过程以及优化泄水闸的泄水流量,介绍了圆形输水隧洞中明满交替水流水力瞬变计算原理和方法。以某大型灌区干渠工程为例,根据窄缝法计算原理,采用显式差分中的扩散法,对圆形输水隧洞中的明满交替水流进行了水力瞬变计算研究。给出了圆形隧洞瞬变流计算的水力要素计算公式,得到了输水流量变化时隧洞不同断面的水深或压力随时间的变化曲线。结果表明:当圆形隧洞水位封顶时,隧洞中的水压力越靠近下游断面,压力突升越剧烈;明流状态下节制闸关闭时间对隧洞内最大水深影响较小,隧洞内的最大水深随着泄水闸泄水流量的增加呈线性减小的趋势,根据数值模拟计算给出了泄水闸合理的设计泄水流量。研究成果可为输水隧洞工程的设计提供借鉴和参考。  相似文献   

18.
滴灌系统灌水器堵塞机理与控制方法研究进展   总被引:11,自引:0,他引:11  
李云开  周博  杨培岭 《水利学报》2018,49(1):103-114
滴灌系统灌水器堵塞问题直接影响灌水均匀度、系统运行效益和使用寿命,是滴灌领域的国际难题之一,而地下滴灌系统中负压吸泥作用与根系入侵效应使得灌水器堵塞机理更为复杂。尤其是水资源短缺与水污染并重的现状迫使滴灌水源多元化、滴灌系统由单一灌溉功能逐步向灌溉施肥等多功能转变以及滴灌技术在高附加值的多年生作物上的应用等因素,对灌水器抗堵塞能力提出了更高的要求。本文通过回顾滴灌系统灌水器堵塞问题研究历程,系统总结了灌水器堵塞类型、测试与评价方法以及发生特征与预报方法,通过建立堵塞物质提取与精细测试方法,分别从堵塞物质形成与生长过程、水源中多物质运移过程两个角度,揭示了灌水器堵塞耦合诱发机制与持续增长机理,通过综合控制堵塞物质来源(前控)、提升自身抗堵塞能力(中排)和有效清除堵塞物质(后清)等多角度建立了灌水器堵塞控制方法,最终提出该领域急需进一步研究的问题和方向。本文旨在为解决滴灌系统灌水器堵塞问题及推动滴灌技术规模化应用与推广提供理论支撑。  相似文献   

19.
在试验室内对发丝滴头进行了自由出流的水力性能试验,试验结果表明:发丝滴头出流流量与工作压力、发丝管长度、发丝管直径和发丝管缠绕直径有关,并根据试验结果,分析拟合出了发丝滴头新出流公式,同时计算了发丝滴头流量偏差率和制造偏差系数,表明试验用发丝滴头制造质量较好。并对发丝滴头进行了升降压试验,结果表明,在升降压过程中,发丝滴头出流量稍有变化,升压过程均匀度好于降压过程。  相似文献   

20.
Hydraulic performances of skimming flow over stepped spillway was studied by means of hydraulic model experiment. The stepped spillway is a modification of the WES (Waterways Experiment Station) standard spillway. The main objective of the experiment was to study the performances of skimming flow over stepped spillway, which include the skimming flow regime, the flow depth on the spillway , the effect of air en-trainment and the energy dissipation. Presented in this paper, the experimental results indicated that the stepped spillway is more effective at dissipating energy, the dissipation ratio decreases with increasing discharge, and the free surface air entrainment on stepped spillway occurs much more upstream than on smooth spillway.  相似文献   

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