本文選題：矩形渠道 + 側堰�。� 參考：《西北農(nóng)林科技大學》2017年碩士論文

【摘要】：灌區(qū)量水設施是衡量灌區(qū)用水管理水平的重要標尺,是對灌區(qū)用水量進行監(jiān)控和計量的基本條件。研究經(jīng)濟實用的量水設施對灌區(qū)節(jié)水、緩解水資源短缺有重要的意義。薄壁堰的量水精度一般高于槽類量水設施。側堰作為一種量水設施,安裝在渠道側邊,直接與小型渠道或田間進水口連通,無需改變渠道斷面結構,具有體型簡單、安裝拆卸方便、精度較高等優(yōu)點,具有很好的應用價值。但目前對側堰水力特性影響因素以及優(yōu)化選型等方面的研究還不深入。本文在前人研究的基礎上,對矩形渠道6種不同堰高和4種不同堰寬的矩形側堰在6種不同流量工況下進行144組試驗,對矩形渠道7種不同堰頂角度的梯形側堰在6種流量工況下進行42組試驗,并采用FLOW-3D軟件對渠道側堰進行了數(shù)值模擬計算。結合試驗和模擬數(shù)據(jù),分析了側堰附近水面線、水頭損失、壅水高度、斷面流速分布、水流流態(tài)等水力因素以及流量系數(shù)與其影響因素之間的關系,主要研究內(nèi)容及結論如下:(1)基于無量綱分析原理,對側堰測流原理進行理論分析,并結合試驗數(shù)據(jù)推導了側堰測流流量公式;(2)分析了矩形側堰的試驗結果和模擬結果,得到了主渠道堰前水面線和側堰附近斷面流速分布的變化規(guī)律,以及堰寬和堰高對矩形側堰水頭損失及壅水高度的影響;對比分析了水面線和斷面流速分布的實測值和模擬值,兩者吻合較好,說明基于FLOW-3D軟件的數(shù)值模擬結果比較可靠;擬合得出的流量公式最大相對誤差為9.87%,平均相對誤差為0.46%,滿足灌區(qū)測流精度要求。(3)分析了梯形側堰的試驗結果和模擬結果,得到了主渠道堰前水面線和側堰附近斷面流速分布的變化規(guī)律,以及側堰堰頂角度對梯形側堰水頭損失及壅水高度的影響;對比分析了水面線和斷面流速分布的實測值和模擬值,兩者吻合較好,說明基于FLOW-3D軟件的數(shù)值模擬結果比較可靠;擬合得出的流量公式最大相對誤差為-8.97%,平均相對誤差為-3.83%,滿足灌區(qū)測流精度要求。(4)基于矩形側堰和梯形側堰的試驗結果和模擬結果,綜合分析了側堰水流流態(tài)、水頭損失、壅水高度及測流精度等水力特性,對矩形側堰和梯形側堰進行了優(yōu)化選型,矩形側堰堰寬不宜過小,堰高不宜過高;梯形側堰堰頂角度不宜過大。針對本文所做的試驗,選擇的矩形側堰適宜堰高為10~15cm,適宜堰寬為30~40cm,梯形側堰適宜堰頂角度為-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 擄~ 6 擄~ 6 擄.
【學位授予單位】：西北農(nóng)林科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：S274.4

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