Research On Flow Measurement And Flow Field Of Flat Gate Based On Field Test And CFD

In order to meet the needs of agricultural irrigation,a large number of irrigation areas have been built in China,but due to extensive management and irrigation methods,the utilization rate of irrigation water is low.Compared with the full-basin automatic control of irrigation areas in foreign developed countries,the precise delivery and distribution of irrigation water,China's irrigation area started late for automation research,equipment technology is backward,flow measurement equipment and control gate are independent of each other.Based on the theory of open channel flat gate flow measurement,this paper studies the flow measurement of the integrated control gate.At present,the research on the control of the flat gate is relatively mature,but the research on the flow measurement of the flat gate is relatively weak.This paper mainly studies the flow measurement of open channel flat gate by combining numerical simulation and field test.On the one hand,the empirical calculation formula of the flow measurement of the flat gate is selected through the field test of free flow and submerged flow of the open channel flat gate.On the other hand,through numerical simulation methods and water level boundary conditions,the flow field distribution of the slab gate under free and submerged outflow conditions was studied respectively,and the relative error between the calculated flow rate and the numerical simulation flow rate was verified by empirical formula to prove that The feasibility of using numerical simulation to study the flow field of the slab gate flow measurement;through the numerical simulation of the integrated sluice gate flowmeter equipped with a flow barrel in front of the slab gate,and analyzing the distribution of the flow field in the flow barrel before the sluice gate to determine the ultrasonic wave The installation area of the flowmeter in the flow barrel.The main conclusions are as follows:1.Combine the field test of free flow and submerged flow of the flat gate to select the flow empirical formula for the flow measurement of the flat gate,and verify the selected flow empirical formulas under these two working conditions,and find the empirical formula of the flow The error between the calculated value and the measured value of the weir in the irrigation area is within 3%,which proves that the calculation accuracy of the flow empirical formula under these two working conditions meets the requirements of the irrigation area and can be used as the flow calculation formula for the flow measurement of the flat gate.Within the accuracy range,it can replace the flow measurement weir of irrigation area.2.Compared with the calculated value of the selected flow empirical formula,the numerical simulation value of the free flow and submerged outflow of the flat gate is within 3%,indicating that the free flow and submerged outflow of the open channel flat gate can be numerically simulated The flow field of the gate is studied to provide a theoretical basis for the flow field study of the flow measurement of the flat gate.For the free flow of the flat gate,the stable area of the flow field before the gate is about 1m~3m,and the stable area of the flow field after the gate is about 13m~15m,for the flooded outflow of the flat gate,the stable area of the flow field before the gate is about 1m~6m,and the stable area of the flow field after the gate is about 10m~17m.3.Through the study of the flow field in the flow barrel before the gate of the integrated plate gate flowmeter,the results show that: the ultrasonic flowmeter should be installed in the central area of the flow barrel,where the water flow is relatively stable and uniform,the inlet head and the gate open The degree has little influence on the flow measurement,and at the same time it avoids the influence of the low-speed area of the inlet section of the flow barrel on the flow measurement accuracy.