Analyzing hydraulic performance of trapezoidal cutthroat flumes

Increasing water head lose to improve the accuracy of flow measurement is a ubiquitous problem in irrigation districts. This research aims to solve the problem. In this context, this research probed into the applicability of the new-type trapezoidal cutthroat flumes in measuring discharge of last trapezoidal channels. Based on Flow-3D, RNG k-ε turbulent model and Tru-VOF technique, numerical simulation was carried out to analyze hydraulic performance of trapezoidal cutthroat flume and rectangular cutthroat flume. Meanwhile, rationality of simulation results was verified by physical prototype test. Results indicated that the distribution of Froude number of trapezoidal cutthroat flume was unimodal; the critical flow appeared near the throat section and the Froude number was less than 0.5 around the upper throat, which could meet the water measurement requirement in irrigation districts; the position of maximum flow rate varied with the change of the flume's boundary. Compared with the rectangular cutthroat flume, both the head loss of trapezoidal cutthroat flume when the flow was large and the measurement accuracy when the flow was small was significantly improved.