山区急弯放宽河段水流分离现象试验研究

文章在分析山区河流形态的基础上,概化出急弯放宽河段的基本平面形态参数,引入了弯道放宽率这个因素,并在前人对弯道水流分离现象研究的基础上,综合考虑了弯道放宽率、弯道中心角、相对弯道中心半径、弗汝德数等因素的影响,通过物理模型试验,对山区急弯放宽河段的水流分离现象的发生和分离区的大小进行了系统的试验研究。研究表明,在文章的试验范围内,总的来说弗汝德数和弯道中心角越大、相对弯道中心半径越小,水流就越容易出现分离,但对弯道凸岸分离区的出现起主要作用的是弯道放宽率,当弯道放宽率大于一定值时,都将发生水流分离现象,而与其他因素没有关系,并且当弯道放宽率较大时分离区也较大。

Experimental study on flow separation of sharp bend with enlarged width in mountainous river

Based on the analysis of river morphology in mountainous areas,the general planar morphology parameters of sharp bend with enlarged width were generalized in this paper.The factor of widening ratio of river bend was introduced.On the basis of previous study on the phenomenon of flow separation at river bend,it comprehensively considered influences on widening ratio of river bend,the angle of channel bend,Froude Number and so on.Through physical model test,systematic experimental researches were carried out on the occurrence of the phenomenon of flow separation at sharp bend with enlarged width and size of separation area.The research indicates that within the testing range of this paper,generally speaking,the bigger the Froude Number and the angle of channel bend are,and the smaller the radius of relative bend,the easier the flow occurs separation.However,widening ratio of river bend plays essential role of occurrence of convex separation area at bend.When the ratio is larger than certain value,flow separation happens and it has no relation to other factors.When the ratio is relatively big,the separation area is relatively big.