宽浅陡槽急流动量分布特征及稳定性研究

Research on the Momentum Distribution and Stability of Shallow Flow in the Wide-steep Channel

采取改变陡槽底坡的系列模型试验,对宽浅急流特性及其对下游消能流态的影响进行分析研究,探讨影响宽浅陡槽泄水消能流态稳定的主要原因。研究表明,宽浅急流能量损耗远大于一般明渠急流,且动量横向分布存在两种不同形态:"椭圆型"与"马鞍型",前者水流稳定性差,有可能产生立轴漩涡,降低消能率;后者水流稳定性好,消能比较充分。同时研究发现,相同流量下,随着弗劳德数Fr的增大,水流的抗扰动能力相应增强。提出宽浅急流是否稳定主要取决于跃前断面宽深比B/h和弗劳德数Fr两个要素,并拟合出用于流态判别的临界曲线,该曲线可为实际工程设计提供帮助。

We analyze the characteristics of wide-shallow rapids and the influence on the energy dissipation of the downstream flow by making a series of model tests with the method of changing the trough＇s slope,in order to explore the main reason which affect the drain of wide-shallow and the stability of the energy dissipation flow.The results show that the energy loss of wide-shallow rapids is much more than the general channel rapids.And there are two different forms of the transverse momentum distribution,which are the ＂Elliptic＂ and the ＂Saddle＂.The first form has poor flow stability and may bring vertical vortex with reducing the rate of energy dissipation,while the second has well flow stability and relatively full of energy dissipation.At the same time,we find that the anti-disturbance of the flow increases corresponding to the increase of Froude number（Fr）.We put forward that if the shallow rapid is steady depends on the breadth depth ratio（B/h）and the Froude number（Fr）.Then we fit the critical curve which can judge the stability,and this cure can provide reference for the designing of the engineering practice.