Experimental Research Of Airfoil-Shaped Measuring Flume For Rectangular Channel

The text pointed out the problem of current water-measuring device on the base of summarizing measuring water technology in irrigation district, and did research on a new stream-lined flume—airfoil-shaped measuring flume. In order to analyse its adv-antages and disadvantages of water-measuring performance and the applied feasibility,The text selected 3 kinds of different contract ratios airfoil-shaped measuring flume a-nd carried on great trial research in rectangular channel, and obtained the certain rese-arch result.The flow formula of airfoil-shaped measuring flume is established in free flow inrectangular channel by experiment and the dimensional analysis. The dimensionless expression showed perfectly the exponential function relationship about relative critical depth and relative upstream water depth of airfoil-shaped measuring flume in different contract ratios. The discharge formula established by the method of dimensional analysis is harmonious. The formula is simple, clear and practical, and have highly precision of flow measurement, the average relative error is only 0.47%.The average relativeerror is only 1.44% when airfoil-shaped measuring flume have a still.Airfoil-shaped measuring flume has highly critical submergence. the submergence changes with changing contract ratio and discharge. With the range of experimental contract ratio, the submergence is between 0.77 and 0.89. the average critical submergence is 0.84,which ensure measuring flume to work in free flow at a great range. The airfoil-shaped measuring flume water head loss isn't higher, and the water head losing has 14% of the total head of water. The experimental results showed that the Froude number related to discharge and contract ratio, the Froude number rises with increasing discharge and contract ratio. The Froude number of airfoil-shaped measuring flume is below 0.35, according with the request of the flow measurement of open channel. In addition, Resistance to water-flow of airfoil-shaped measuring flume is small, The back water height shall not exceed 10cm.According to experiment in rectangular channel and analysis of water-measuring performance about airfoil-shaped measuring flume, airfoil-shaped measuring flume have several advantages over other form of flume: higher precision of flow measurement, simple,clear and practical discharge formula, less resistance to water-flow, higher critical submergence, smaller water head loss, simple structure. Premilinary syudy showed that airfoil-shaped measuring flume is a new type water-measuring device , which fit to measure flow in rectangular channel, and endowed with a good prospect of application and extension.