倒虹吸进水口过渡段内流速横向分布试验研究

Experimental Study on Transverse Distribution of Flow Velocity in Transition Section of Inverted Siphon Inlet

倒虹吸是常见的输水建筑物,因倒虹吸进水口前端来水流量不同而出现过渡段内水面横向波动现象,从而加剧水流紊动强度,不利于倒虹吸管道运行。选取南水北调中线工程西小屯沟排水倒虹吸作为参照,构建水工模型进行试验研究,通过对照不同来水流量下过渡段内的水面横向变化、水面沿程变化以及垂向流速的横向变化,分析不同来水流量下过渡段内的水流特征,剖析水面波动和水流紊动强度加剧的深层原因。结果表明:倒虹吸进水口前端存在明显水跃现象,导致过渡段内水流沿断面横向呈非对称分布;受过渡段内水深的影响,过渡段内水流紊动强度随来水流量的增大而减弱。

Inverted siphon is a common water delivery structure, due to the different water flows at the front of the inverted siphon inlet, the transverse fluctuation of the water surface in the transition section occurs, thereby aggravating the turbulent intensity of the water flow, which is not conducive to the operation of the inverted siphon pipeline. Selecting the inverted siphon drainage of Xixiaotungou in the Middle Route of the South-to-North Water Diversion Project as a reference, a hydraulic model was built for experimental research. By comparing the transverse changes of the water surface in the transition section under different inflow flows, the changes of the water surface along the course, and the transverse changes of the vertical velocity, the water flow characteristics in the transition section under different inflow discharges were analyzed and the deep-seated causes of water surface fluctuation and the enhancement of water turbulence intensity were analyzed. The results show that the water flow in the transition section is distributed asymmetrically along the cross section due to the obvious hydraulic jump at the front of the inverted siphon water inlet;affected by the water depth in the transition section, the turbulent intensity of the water flow in the transition section decreases with the increase of the incoming water flow.