Study On The Flow Characteristics3D-Numerical Simulation Of Long Distances Inverted Siphon

Inverted siphon is important conveyance structures which has been master and used for thousands ofyears by humans. With the progress of science and technology, more and more large diameter,long-distance inverted siphon is used in water diversion project. Water supply project in northern Xinjiangcontains two large inverted siphon: Xiao Wacao and San Gequan inverted siphon project put into use, theactual flow and design flow vary greatly, flow capacity of Xiao Wacao inverted siphon is too small, and oftoo large more than36%for San Gequan. As the model test simulates inverted siphon cannot guatantee allhydraulic elements similar with the prototype at same time and the prototype observation cannot study theflow field internal. In recent years, scholars making use of Turbulent Numerical Simulation in waterconservancy project gradually become in-depth, detailed, realized Basic theoretical research andengineering practice Combinaton. The numerical simulation has advantages in solving complex problems,numerical simulate Xiao Wacao and San Gequan inverted siphon flow characteristics using the FLUENTcommercial software, concluded as follows:(1)Numerical simulation to Xiao Wacao inverted siphon under a certain flow (Q=16.35m~3/s) usingdifferent roughness height spreadsheet when simulate head loss along pipe, show the roughness height ofXiao Wacao inverted siphon is about0.00002m. Provide reference for FRP pipe inverted siphon simulation.Projections of the roughness of the glass fiber reinforced plastic and the actual is closer.(2)Since the roughness design of San Gequan is larger, making the flow capacity greater than the designvalue of the actual run-time. Based on the measured data of the flow water level relationship, Projectionscorresponding to the water level to increase the flow of26.25m~3/s, take the water level of grit chamber andthe downstream channel that speculated as the known conditions into the model. Calculated water depth ofthe water chamber and the downstream outlet channels measuring point and curve were fitting contrast, theresults more realistic.(3)Simulate the large flow inverted siphon charging process for two conditions: Q=10m~3/s and Q=14m~3/s.Results: Q=10m~3/s water charging process more stable, pressured section of a small amount of gasdeposition. Since the flow is less than the design flow, resulting in the remaining head and the water has notbeen charged to the normal operation of the upstream height. Q=14m~3/s water backflow during chargewater process, some part of the free flow and some part of the pressure flow in siphon, the flow pattern isvery unstable. Accordingly, the water filling process need to adjust gate, but the actual operation of thefilling process can be appropriate to increase the charge on the basis of the original1m~3/s water flow. Onthe basis, the mathematical model needs to be improved, and other conditions of water filled with water tosimulate the process, to make the results more convincing.