Experiment And Numerical Simulation Research On Wing Pillar-shaped Measuring-flume In Common Irrigation Channels

Irrigation district water-measuring is an important measure for rational use of irrigation water resources,achieve planned water use and on-demand water use.The study of large-scale water facilities is a crucial task to promote water-saving agriculture,agricultural water rights allocation and water price reform.This paper summarized the development status,characteristics and applicable conditions of commonly used water measuring equipment in Irrigation area.Aiming at the advantages of simple structure and accurate flow measurement of the Wing Pillar-shaped Measuring-flume.The hydraulic characteristics of the Wing Pillar-shaped Measuring-flume in U-shaped channel and trapezoidal channel were studied by model test and numerical simulation.The test was carried out in two channels through four different tank shrinkage ratios.Through the analysis of upstream water level,flow rate and contraction ratio,the flow calculation formula of each contraction ratio condition is obtained by fitting.The flow measurement formula is simple and easy to use,the average flow error of trapezoidal channel and U-shaped channel flow formulas is 2.47% and 2.43%,respectively.Both meet the accuracy requirements of the "Irrigation Channel System Water Standards"(GB/T 21303-2017).And analyzed the froude number,height of swell,the critical submergence and the loss of head in the upper reaches of measuring-flume,the results show that the water tank upstream froude number are less than 0.4,and the U-shaped channel’s is lower than that of trapezoidal channel,which proves that the upstream flow of the water tank on the U-shaped channel is more likely to form a smooth slow flow;The experimental results show that the critical submergence is higher on both channels,both of which can reach above 0.85,and there is a large free flow range;The height of swelll is generally lower than the super high of the channel,can be used for irrigation district reconstruction;The water head loss caused by the flow through the flume accounts for 7.12%~29.51% of the total head in the upstream.Aiming at the problem of limited test combination and diseconomy,the FLUENT software was used to simulate the three-dimensional flow characteristics of the Wing Pillar-shaped Measuring-flume in trapezoidal channel with two contraction ratios(ε=0.50,ε=0.58)by the coupling of the standard k-ε turbulence model and the VOF method,flow adjustment range is between 10L/s and 60L/s.The numerical calculations show the flow and the variation of water surface line,simulated streamline and velocity field.Compared with the model test,the results show that the simulated flow pattern is basically consistent with the experimental display,the average error between thesimulated surface line and the measured value is 3.80%,and average error between simulated flow and test flow is 3.77%,explain that the established numerical model can simulate the flow phenomenon of the Wing Pillar-shaped Measuring-flume well.Through the modal test and numerical simulation of the Wing Pillar-shaped Measuring-flume on two channels,it is shown that the measuring flume has a good application prospect and can represent the new type of flume applied in the irrigation area.FLUENT software can be used for further research work on the Wing Pillar-shaped Measuring-flume.