Flow Gauging Analysis And Numerical Simulation Of Measurement And Control Integrated Gate In Silt Content Water Channel

With the rapid development of computer and information technology,irrigation district information management and flow gauging automation technology have been widely used in all over the world.To realize the sharing of water resources is the development tendency through information exchange between water resources allocation systems and management information systems by scientific and technological approaches.It is also an inevitable requirement of modern irrigation district information management at same time.Although the automatic technical equipment of measurement and control integrated gates from Australia Rubicon Company have been introduced in some districts of our country,the research about its application effect to the high silt content water has a little of results due to the irrigation flow from Yellow Rive in mostly agricultural irrigation areas of Ningxia.The research object comes from Nanshantaizi pumping irrigation district that has been constructed by the measurement and control integrated gate of Rubicon and with the equipment of flume without throat still keeping well at same time,where located at Yellow-rive irrigation areas of Zhongwei,Ningxia.The branches flow gauging performance with the measurement and control integrated gate have been conducted comparing to the flume without throat by using to analysis the site test data,checking the results with velocity-meter,theoretical and numerical simulating based on the field investigation,visiting the engineer and staff employee from the irrigation district,consulting and collecting real-time flow measurement data,and so on in this thesis.According to the theory of hydraulics,the mathematical models of high silt content flow for the measurement and control integrated gate and the non-throat measuring flume have been established,respectively.The influence on hydraulic characteristic of silt content water from these branches flow gauging performances with the measurement and control integrated gate and the non-throat measuring flume have been respective simulated and analyzed by using ANSYS Fluent finite element software under various operating conditions.The influence mechanism on accuracy of flow gauging for high silt content water with the measurement and control integrated gate has been discussed combining with its measurement principle.The main research contents and results are as follows.(1)The data of flow gauging respective from the measurement and control integrated gate and the non-throat measuring flume have been compared and analyzed on the 18 branch canals in the irrigation area during irrigation period(flood season and non-flood season),and results show that the flow gauging value of the measurement and control integrated gate is larger than that of the non-throat measuring flume,and the silt contents affect the accuracy of flow gauging due to the result is well at non-flood season.The checked data with velocity-meter meter are also show that the flow gauging error value from the measurement and control integrated gate is larger than that of the non-throat measuring flume.(2)The numerical simulation results from the measurement and control integrated gate show that the fine particle sediment has little influence on the flow structure in the measuring box,and its velocity and turbulent kinetic energy have no obvious change;the velocity and turbulent kinetic energy of a part of flow near the gate hole are relatively large,and the turbulent kinetic energy of pure water is larger than that of silt content water;the velocity of the contraction section increases first and then decreases with the increase of water depth,and the turbulent kinetic energy decreases with the increase of silt content.(3)The numerical simulation results show that the silt content has a certain influence on the flow coefficient and flow rate index to the non-throat measuring flume,and the silt content has a certain influence on the accuracy of flow gauging with a non-throat measuring flume.(4)The influence of silt content on the flow gauging accuracy of the integrated board gate is mainly due to the different distribution of silt particles with various particle sizes in the fluid,the different concentrations of silts make the ultrasonic wave attenuation in propagation process,and leads the deviation of the signal trigger point,so that to affect the accuracy of the time lag measurement;secondly,the silt content affects the turbulent kinetic energy distribution of water flow in the metering box,so as to lead the measuring error of ultrasonic flow meter.The research on the silt content flow gauging of the measurement and control integrated gate can provide theoretical support for the popularization and application of the automatic technical equipment of flow gauging in high silt content water channel.