液压坝群对变曲率河道水力特性的影响

Influence of Lifting Dam Group on Hydraulic Characteristics of Variable Curvature Channel

通过在变曲率水槽中加入液压坝群,研究了4种工况下水槽轴线上纵向流速沿垂线的分布、紊动能及水面变化特性。结果表明:①无液压坝时,变曲率河道中顺直段的垂线流速最大值出现在距水槽底部0.4倍水深处;在过渡段及弯顶附近近水面流速最大;加入液压坝群后,各液压坝上游断面沿水深方向的流速变化很小,最大值出现在距槽底0.4倍水深处,而各坝下游断面流速分布及大小差异较大。②对于4种不同工况,紊动能沿水深方向均减小。液压坝的存在减小了河道中水流的紊动能,无液压坝与液压坝全部竖起时各水深处紊动能均值沿水深方向的比值分别为1.80(距槽底0.8倍水深处)、3.02(距槽底0.4倍水深处)、5.92(距槽底0.2倍水深处),表明液压坝对近槽底处紊动能的影响更大;当液压坝的中间扇放倒后,河道紊动能沿程分布变化较大,且紊动能值也较其他工况大,呈波浪式分布。③竖起的液压坝越多,最末级液压坝上下游水位差越大,最大为0.245倍静水深。

The characteristics of distribution of velocity,turbulent kinetic energy and water surface variations were studied by adding the lift⁃ing dam group in the variable curvature flume under four cases.The results show that a)the trend of the velocity distribution is related to the curvature of the section when there is no lifting dam in the channel.The maximum velocity is in the 0.4 times depth which measures from the bottom of the flume in the straight section,however the maximum is near the surface in the excessive parts of the direct and curved and near the maximum curvature sections.After adding the dam group,the changes of velocity along the depth direction are very small in the upstream of each dam and the maximum velocity is in the 0.4 times depth,while the velocity distribution and value have large differences in the down⁃stream.b)The turbulent kinetic energy decrease along the water depth under each case.On the other hand,the existence of hydraulic dam reduces the turbulence kinetic energy.When the middle lifting dam is put down,the turbulent kinetic energy of the channel changes greatly along the range and the turbulent kinetic energy is larger than that of other cases,which presents a wave distribution.c)The more dams are built,the differences between the upstream and downstream water level are larger at the last dam,and the maximum is that the difference of upstream and downstream water depth is 0.245 times than that of static depth.