明渠扩散段急流运动特性及调控方法研究综述

依据文献分析了有限宽度水槽突然扩散、固定扩散角渐变扩散、无边界平板扩散和急流扩散4种典型明渠扩散段水流的共同流动特征.给出了有限宽度水槽突然扩散段水流宽度的沿程发展规律,以及在平底明渠急流扩散段设计时,为防止水流脱离的扩散角计算方法和突然扩展区急流扩散的边界方程;通过不同底坡比降的试验和原型资料分析,论述了陡坡扩散区水深沿程变化特点、沿程各断面横向分布规律,介绍了陡坡上水平扩散角的计算方法与扩散角最大值的存在.通过大扩散角水槽试验,发现在扩散段不同流态的过渡水流现象及稳定性不一样.上游来流为急流时,下游水跃进入扩散段就是水流失稳、主流偏转的开始;采用潜没式三角翼可以防止扩散段回流发生,提高过流均衡性.

The Research Summary of Flowing Characteristics and Control Methods of Supercritical Flow in Diffused Section of Open Channel

The same supercritical flow characteristics of four kinds of diffused section of open channel were analyzed,such as abrupt diffusion section of flume with limited width,transition section with fixed angle,diffusion section of the flat with no border and supercritical flow diffusion section of steep slope. The developing law of the flow width along the stream was given in the abrupt diffusion section of flume with limited width. The calculation method of the spread angle was introduced for preventing flow separation when designing in the supercritical flow diffusion section of open channel with plane bottom,and the boundary equation of supercritical flow diffusion was given in the abrupt diffusion flume. By experiments in different bottom slope gradient and analysis of prototype observation data,the transverse distribution law of cross sections and changing characteristics of depth of water along the steep slope diffusion section were discussed. The calculation method of horizontal spread angle on steep slopes were introduced,as well as the maximum value of spread angle. Through the experiment of the flume with large spread angle,it is found that transitional flow phenomenon and stability of different flowing form are different in diffusion section. When the incoming flow is supercritical flow,the flow begins to become instable and deflecting once the hydraulic jump occurs in the diffusion section. The submerged triangle wing can restrain the occurrence of circle flow and improve the flow balance.