| Irrigation water measurement is essential for reasonable dispatch of irrigation water, correctly carrying out water using planning, and strengthening economic management. Thus, to research and development new canal flow-measuring devices which is characteried by its simple structure, high precision, small head loss and lower lost is critical task of promoting the development of irrigation.The characteristic of water measure equipment and its research status as well as the suitable condition in domestic and overseas has summarized in this article. According to the analysis of weakness in flume standardization, with the combination of theoretical analysis and experimental study and numerical simulation, this paper studies the standardization of the airfoil-shaped measruing flume.The physical model test adopted rectangular channels combined with U-shaped channels and airfoil-shaped flume built in the rectangular channels, then selected four different contraction ratio to test in Northwest A&U university. The results shows that the formula which established by the dimensional analysis in state of free flow can meet the requirements of dimensional analysis harmonious, besides it's concise, practical and high accuracy flow measurement, the average flow rate of relative error is only 1.89% which consistent with water measurement specification. The experiment also shows that in the range of experiment contraction ratio the critical submergence in airfoil-shaped measuring flume is 0.8~0.9 , it can guarantee the measurement volume running in larger scope under the free outflow. The Froude number is less than 0.5, this report the water flows slowly and stable in previous to measurement flume.By making use of the Flow-3D software, three-dimensional numerical model of the airfoil-shaped flume in different conditions were introduced, and the hydraulic parameters such as flow forms of the volume, simulated water depth and free water surface were simulated and analyzed. Compared the results calculated by software with data measured by model experiment, it is proved that using Flow-3D software can accurate simulation the hydraulic parameters of the airfoil-shaped flume , and the numerical model established in this paper for description hydraulic of the flume are reliable and referable. At different slope of the U-shaped channels, the numerical tests are performed to discuss effects of slope on contraction ratio of the airfoil-shaped measuring flume. Results show that the larger contraction ratio corresponds to steep channel slope.Based on the standardization theory, physical model test and numerical simulation, the standardization structure of airfoil-shaped measuring flume is proposed. On the basis of a comprehensive summarizing of existing results, this paper aslo induces design principle and method of airfoil-shaped measuring flume, as well as construction requirements. |
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