刚性植被群对连续弯道水力特性的影响研究

Research on the Influence of Rigid Vegetation Groups on Hydraulic Characteristics of Continuous Bend

为了探究植被对天然弯曲河流水力特性的影响,通过连续弯曲水槽试验,设计均匀、簇状两种布设形式分别模拟人工规律种植以及自然丛生的植被群,对比分析不同的布设形式对弯道水流流场、水动力轴线、紊动能分布的影响。结果表明:①连续弯槽中水流流场出现明显的流速分区:高流速区靠近凸岸,低流速区则分布在凹岸附近;底层水流与表层水流相比,高流速区分布范围扩大,低流速区减小;布设植被后高流速区分布范围增加,低流速区则剧减,且簇状布设的影响幅度明显大于均匀布设。②连续弯槽水流的水动力轴线偏离正常位置,其沿程表现出先贴近凸岸后脱离凸岸的动态变化过程;植被布设大大延缓了该进程,且簇状布设的延缓程度大于均匀布设。③连续弯槽水流的紊动能沿程分布呈现出不均匀性,最大值出现在弯顶附近区域;从紊动能数值变化可知,植被布设使得水流的紊动能普遍增加,且簇状布设的影响程度大于均匀布设。

In order to explore the effect of vegetation on the hydraulic characteristics of naturally curved rivers,this paper designs two layout forms of uniform and cluster to simulate artificial regular planting and natural cluster vegetation groups respectively.Through continuous bending flume experiment,the paper comparatively analyzes the influence of different layouts on flow field,hydrodynamic axis and turbulent kinetic energy distribution.The results show that:①There are obvious velocity zones in the flow field of the continuous curved channel:the high velocity zone is close to the convex bank,and the low velocity zone is distributed near the concave bank.Compared with the surface flow,the distribution range of the high velocity zone of the bottom flow is expanded,and the low velocity zone is reduced.The distribution range of high velocity area increases and that of low velocity area decreases greatly after vegetation distribution,and the influence of cluster layout is obviously greater than that of uniform layout.②The hydrodynamic axis of the continuous curved channel flow deviates from the normal position,which shows the dynamic change process of closing to the convex bank firstly and then leaving the convex bank.Vegetation layout greatly delays the process,and the delay degree of cluster layout is greater than that of uniform layout.③The turbulent kinetic energy distribution along the continuous curved channel flow is uneven,and the maximum value appears near the top of the bend.From the numerical changes of turbulent kinetic energy,it can be seen that the vegetation layout makes the turbulent kinetic energy of the water flow generally increase,and the influence of cluster layout is greater than that of uniform layout.