Structure Optimization And Discharge Calculation Method Of New Type Flume For Flow Measurement In Irrigation District

The cylinder measuring flume is a miniature discharge measuring equipment, which is formed by setting a removable post or canister for engendering critical state of flow here on the axes in the original prism channel. It isn't necessary to change the original channel profile and it is used for symmetrical rectangular, trapezoidal, U-shaped etc channels. The cylinder measuring flume can expediently fix the water sensing device in the post for forming a removable or immovable measuring equipment.The article firstly does the research on universal flow measurement theory in the cylinder measuring flume, and educes the common discharge calculation formula for different figures of cylinder measuring flume in trapezoidal and U-shaped channel. Secondly, in the trapezoidal channel which profile is that the base width is 20cm, the depth of channel is 20cm, the slope coefficient 1.0, and U-shaped channel which profile is that the depth of channel is 40cm, the radius of bottom circular arc, the external dip angle α of abutment wall is 8°, the article does a series of experiment researches on many of cylinder measuring flumes, such as circular, pier shaped, elliptic and diamond cylinder flumes, and discusses the variance of discharge coefficient, submergence factor, backwater height, head loss and critical submergence degree for each of cylinder measuring flume. On this basis, the article optimizes the structure shape of the cylinder measuring flume further. Furthermore, using standard k-ε double equation turbulence model, it simulates the three-dimensional water movement of the circular and pier shaped cylinder measuring flumes, and makes researches on the discharge coefficient of the cylinder measuring flumes in the larger range. Finally, according to the researches of flume experiment and numerical simulation, the article puts forward a new method of flow rate calculation for the circular and pier shaped cylinder measuring flumes, which is much more application, and can meet the need of the free outflow and submerged discharge, meanwhile it analyses the precision of the new method, and provides the theory for the broad application of the circular and pier shaped cylinder measuring flumes.