深水明渠附着水下空间体的水动力特性与体型优化

Hydrodynamic characteristics and shape optimization of underwater space body attached to deep-water open channels

大型长距离输水明渠边坡衬砌破坏后,受供水保证率制约通常只能不停水修复,而现有施工技术在深水渠道中难以使用,寻找快速环保地进行明渠不停水修复已成为亟待解决的重大技术难题。突破传统施工围堰概念,提出使用“水下无底拱穹结构”作为大型明渠不停水修复的施工平台。以南水北调中线干渠某渠段为例,采用数值模拟与物理模型验证相结合的方法,开展了空间体的水动力特性及体型优化研究。首先基于水下空间体的构造与选定的约束条件,利用Rhion和Flow 3D软件搭建了研究渠段的三维水动力学模型;分别对设计的三种体型水下空间体进行了水动力数模计算,分析了渠道流态与流场、断面流速分布、回流强度、壅水及阻力损失等水力要素的特征,计算了空间体的绕流阻力,对比总结了三种体型空间体的水动力学特征。结果表明,半椭圆形水下空间体绕流阻力较小,对渠道过流能力影响最小,可考虑作为水下空间体的应用选型。本文的研究为渠道内快速开展不停水维修提供了新思路与技术参考。

After the slope lining of large-scale and long-distance open channel is damaged,it can only be repaired without stopping water flow due to the restriction of water supply guarantee rate.However,the existing construction technology is difficult to use in deep water channel.How to quickly and environmentally repair open channel without stopping water flow has become a major technical problem to be solved.This paper breaks through the traditional concept of construction cofferdam,and puts forward the use of"underwater bottomless arch dome structure"as the construction platform for large open channel repair without stopping water flow.Taking a section of main canal in the middle line of the South to North Water Diversion Project as an example,the hydrodynamic characteristics and shape optimization of space body are studied by combining numerical simulation with physical model validation.Firstly,based on the structure of underwater space body and the selected constraints,this paper establishes a three-dimensional hydrodynamic model of the channel section by using the softwares of Rhino and Flow 3D.Next,the hydrodynamic numerical analysis of three types of underwater space body schemes is carried out and the flow characteristics of different schemes,such as channel flow pattern,velocity,recirculation zone,backwater and resistance loss,are analyzed.Then the circle resistance around the underwater space body is calculated and the hydrodynamic characteristics of the three types are evaluated.The analysis results show that the circle resistance of the underwater space body with a semi-oval section is small,and the influence on the channel flow capacity is minimal,which can be considered as the application and selection of the underwater space body.The research in this paper provides innovative ideas and technical reference for the rapid development of non-stop water maintenance in the channel.