矩形渠道侧堰水力性能研究

发布时间：2018-04-25 10:33

本文选题：矩形渠道 + 侧堰　；参考：《西北农林科技大学》2017年硕士论文

【摘要】：灌区量水设施是衡量灌区用水管理水平的重要标尺,是对灌区用水量进行监控和计量的基本条件。研究经济实用的量水设施对灌区节水、缓解水资源短缺有重要的意义。薄壁堰的量水精度一般高于槽类量水设施。侧堰作为一种量水设施,安装在渠道侧边,直接与小型渠道或田间进水口连通,无需改变渠道断面结构,具有体型简单、安装拆卸方便、精度较高等优点,具有很好的应用价值。但目前对侧堰水力特性影响因素以及优化选型等方面的研究还不深入。本文在前人研究的基础上,对矩形渠道6种不同堰高和4种不同堰宽的矩形侧堰在6种不同流量工况下进行144组试验,对矩形渠道7种不同堰顶角度的梯形侧堰在6种流量工况下进行42组试验,并采用FLOW-3D软件对渠道侧堰进行了数值模拟计算。结合试验和模拟数据,分析了侧堰附近水面线、水头损失、壅水高度、断面流速分布、水流流态等水力因素以及流量系数与其影响因素之间的关系,主要研究内容及结论如下:(1)基于无量纲分析原理,对侧堰测流原理进行理论分析,并结合试验数据推导了侧堰测流流量公式;(2)分析了矩形侧堰的试验结果和模拟结果,得到了主渠道堰前水面线和侧堰附近断面流速分布的变化规律,以及堰宽和堰高对矩形侧堰水头损失及壅水高度的影响;对比分析了水面线和断面流速分布的实测值和模拟值,两者吻合较好,说明基于FLOW-3D软件的数值模拟结果比较可靠;拟合得出的流量公式最大相对误差为9.87%,平均相对误差为0.46%,满足灌区测流精度要求。(3)分析了梯形侧堰的试验结果和模拟结果,得到了主渠道堰前水面线和侧堰附近断面流速分布的变化规律,以及侧堰堰顶角度对梯形侧堰水头损失及壅水高度的影响;对比分析了水面线和断面流速分布的实测值和模拟值,两者吻合较好,说明基于FLOW-3D软件的数值模拟结果比较可靠;拟合得出的流量公式最大相对误差为-8.97%,平均相对误差为-3.83%,满足灌区测流精度要求。(4)基于矩形侧堰和梯形侧堰的试验结果和模拟结果,综合分析了侧堰水流流态、水头损失、壅水高度及测流精度等水力特性,对矩形侧堰和梯形侧堰进行了优化选型,矩形侧堰堰宽不宜过小,堰高不宜过高;梯形侧堰堰顶角度不宜过大。针对本文所做的试验,选择的矩形侧堰适宜堰高为10~15cm,适宜堰宽为30~40cm,梯形侧堰适宜堰顶角度为-6°~6°。
[Abstract]:The water measuring facilities of irrigation district is an important scale to measure the level of water use management in irrigation area and is the basic condition for monitoring and measuring water consumption in irrigation area. It is of great significance to study the economical and practical water measuring facilities for saving water and alleviating the shortage of water resources in irrigation area. The measuring accuracy of thin wall Weir is generally higher than that of trough type water measuring facilities. As a water measuring facility, the side Weir is installed on the side of the channel and directly connected with the small channel or field water inlet. It does not need to change the cross-section structure of the channel. It has the advantages of simple shape, convenient installation and disassembly, high precision, etc. It has good application value. However, the research on hydraulic characteristics and optimal selection of contralateral Weir has not been further studied at present. On the basis of previous studies, 144 groups of experiments were carried out on 6 rectangular side Weir with different Weir height and 4 different Weir widths under 6 different flow conditions. 42 groups of experiments were carried out on 7 trapezoidal side Weir with different top angles of rectangular channel under six flow conditions, and the numerical simulation of channel side Weir was carried out with FLOW-3D software. Based on the experimental and simulated data, the relationship between hydraulic factors, such as water surface line, head loss, backwater height, cross-section velocity distribution, water flow state and flow coefficient, is analyzed. The main research contents and conclusions are as follows: (1) based on the dimensionless analysis principle, the flow measurement principle of the lateral Weir is theoretically analyzed, and the formula of flow measurement flow of the side Weir is derived by combining the experimental data.) the experimental results and the simulation results of the rectangular side Weir are analyzed. The variation law of velocity distribution in front of main channel Weir and section near side Weir, and the influence of Weir width and Weir height on head loss and backwater height of rectangular side Weir are obtained, and the measured and simulated values of water surface profile and section velocity distribution are compared and analyzed. The good agreement between the two shows that the numerical simulation results based on FLOW-3D software are reliable. The maximum relative error and average relative error are 9.87 and 0.46 respectively, which meet the requirement of flow measurement accuracy in irrigation area.) the experimental results and simulation results of trapezoidal side Weir are analyzed. The variation law of the velocity distribution of the front water surface line and the cross section near the side Weir of the main channel and the influence of the top angle of the side Weir on the head loss and backwater height of the trapezoidal side Weir are obtained. The measured and simulated values of velocity distribution of water surface line and section are compared and analyzed, which shows that the numerical simulation results based on FLOW-3D software are more reliable. The maximum relative error of flow formula is -8.97 and the average relative error is -3.83, which meets the requirement of flow measurement accuracy in irrigation area.) based on the experimental results and simulation results of rectangular and trapezoidal side Weir, the flow state and head loss of the lateral water flow are comprehensively analyzed. The hydraulic characteristics such as backwater height and flow measurement accuracy are optimized for rectangular and trapezoidal side Weir. The width of rectangular side Weir should not be too small, Weir height should not be too high, and the top angle of trapezoidal Weir should not be too large. According to the experiment done in this paper, the optimum Weir height of rectangular side Weir is 10 ~ 15 cm, the suitable Weir width is 30 ~ 40 cm, and the angle of top of trapezoidal side Weir is 6 掳~ 6 掳~ 6 掳.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S274.4

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