| The water-diversion is a common building for the irrigation canal system in the irrigation area.The water level in the main channel and the water-diversion channel can be controlled by adjusting the gate and the opening of the diversion gate,so that the water flow from the outlet enters the side channel according to the water volume plan.In order to meet the requirements of gravity flow irrigation,the bottom elevation at the side channel inlet is higher than the field elevation.After the completion of the diversion port,there is a good correspondence between the diversion flow rate and the channel,which can be used as a flow measurement facility to avoid the head loss of the special water measurement facility.In addition,the integration of measurement and control of the channel water volume can be achieved to improve the modern management level of the irrigation area.The research of the channel hydraulic characteristics is aimed at the same height at the bottom of the main channel,but the irrigation canal system is decorated in mostly at the bottom of the side channel entrance elevation is higher than the main channel,so the research on hydraulic performance of side channel bottom elevation above the main channel was studied,and three height of side channel bottom,five channel width ratio,5 discharge and 5 diversion ratio under the same discharge(different diversion ratio is obtained by controlling the end of the main canal’s fluid level),a total of 375 pairs of experiment,combining with the FLOW-3D software numerical simulation,The hydraulic performance of the rectangular diversion is studied,and the hydraulic characteristics of the main channel at the water-diversion,such as the fluid surface profile,flow angle,velocity of cross section,recirculation zone,and the relationship between the flow coefficient at the water-diversin and its influencing factors,are analyzed.The main research contents and conclusions are as follows:(1)Based on the principle of energy conservation and dimensional analysis,the discharge formula and flow coefficient of the side channel were theoretically analyzed,and the calculation formula of the discharge of the side channel inlet and the relevant factors affecting the flow rate coefficient were obtained.(2)By analyzing the experiment and simulation results of the rectangular channel waterdiversion,the relationship between the surface profile of the main channel at the waterdiversion,the diversion ratio and the head above the relative weir,the Froude number on the upper and lower of the main channel,and the relationship between the flow angle and the head above the relative weir are obtained.According to the influence factors of flow coefficient obtained by dimensional analysis,the relation between the ratio of bottom height of side channel and weir head and the flow coefficient of side channel water-diversion was fitted.(3)The experimental data and simulated data of the rectangular channel water-diversion were compared and analyzed.The measured values of water depth and section velocity were in good agreement with the simulated values,and the relative errors were all less than 10%,indicating that the simulation results of the rectangular channel water diversion outlet using flow-3d were credible and reliable.The fluid depth of the main channel rises gradually at the water-diversion,which is similar to a straight line backwater,and the fluid depth at the downstream of the water-diversion reaches the maximum.The distribution regular of flow velocity in all sections of the main channel is roughly the same under different water depths.The flow of the main channel higher than the bottom of the side channel causes disturbance to the flow lower than the bottom of the side channel,so that the flow in front of the bottom of the side channel has an upward velocity.(4)Combined with rectangular channels in the literature angle 45 °water experimental data,using FIOW-3D for the same condition is simulated,and the results of velocity are compared,simulated values and measured values relative error less than 10%,using FLOW-3D simulation results of different angles is credible;The relation between the discharge coefficient of the channel at the lower side of each branch angle and the head of the relative weir is fitted,and the maximum relative error is less than 11%. |
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