通過對不同堰板的流量係數進行比較會發現，不同堰板流量係數不同，但正反方向的流量大致相同，后得知因爲本試驗儀器較小所以正反沒有產生較大差異，若如果在實際大型設備上，會有顯著的一個差異。同時我們將數據進行回歸分析會發現，梯形堰口的流量係數會介於矩形與三角形之間。In a water conservancy project, a weir can measure the flow on the control section of an open channel.Weirs are also commonly used in water purification companies and sewage treatment plants of water companies to estimate the amount of water treated.This test is a reduced version of the artificial channel weir.By measuring the upstream water level,the height difference of the weir mouth,the theoretical flow can be obtained through calculation formulas.By comparing the theoretical flow and actual flow under different shapes, the approximate range of the flow coefficient can be known.
This test must be matched with a hydraulic test bench. Water flows from the test bench's water outlet and flows under the instrument.The upstream part of the weir is divided into two parts by a flat plate.The left of the weir is a static water tank and the right of the flat is an inlet tank. After the water flows from the water outlet,it flows up into the water tank along the pipe.At the center of the flat plate, there is an orifice, which is connected to the orifice of the bottom of the transparent measuring bucket outside the tank by a transparent soft plastic pipe. Due to the principle of the connecting pipe, the static water tank and the measuring bucket are kept at the same height.The water measuring weir plate is fixed to the support plate with screws. A weird water tank with a slightly inclined bottom plate is located downstream of the weir opening. After the water overflows from the weir opening, it flows from the opening under the tank through a transparent plastic hose to measure the water opening. Flow test to the weir mouth constitutes a cycle.
By comparing the flow coefficients of different weir plates,it will be found that the flow coefficients of different weir plates are different, but the flow in the forward and reverse directions is approximately the same.It was learned that because the test instrument is small,there is no large difference between the positive and negative.There is a significant difference in actual large equipment.At the same time,we perform regression analysis on the data to find that the flow coefficient of the trapezoidal weir will be between the rectangle and the triangle.