丁坝群作用尺度理论及累积效应机理研究

发布时间：2018-07-08 17:27

本文选题：丁坝 + 作用尺度　；参考：《浙江大学》2014年博士论文

【摘要】：丁坝是一种常见的涉河建筑物,广泛应用于治河工程、防洪工程、航道整治工程以及河滩围垦工程中。丁坝作为人类施加于河流系统的影响,在一定程度上会对河流系统产生干扰,为了更好地发挥丁坝的各项功能,工程实际中丁坝往往以“群”的形式出现。然而,目前针对丁坝所开展的研究无论是水流特性还是冲刷机理更多地着眼于单体丁坝上下游局部河段范围内对河床或水流的局部影响,而对由一系列丁坝所组成的丁坝群对河床及水流的综合影响和累积影响涉及较少。然而,不同间距下丁坝之间的关联性不同,从而产生的累积影响不同,因此,有必要开展丁坝作用尺度划分的研究。目前,一些涉河工程(如水库、电站、堤坝、人工运河等)的累积影响研究已经开展并取得了一定的研究成果,而丁坝作为其中的一种,关于其累积影响的研究却鲜有涉及。因此,在丁坝作用尺度划分的基础上,开展不同作用尺度之下丁坝群累积效应机理的研究具有一定的学术价值,对认识和评价涉河工程群对河流健康的影响亦有重要的意义。本文首先在浙江大学建工试验大厅开展水槽试验,获得数组丁坝群流场的试验资料,随后,选取三种不同方法求解N-S方程的紊流模型和两种自由表面处理方法对丁坝群流场进行数值模拟,在综合考虑模拟精度和模拟时间的前提下,分别获得适合非淹没丁坝和淹没丁坝流场模拟的数学模型。在前人研究的基础上,采用数值水槽定性研究非淹没丁坝和淹没丁坝作用尺度的划分准则,并对每种划分准则的优缺点进行定性分析比较,以此建立丁坝群作用尺度概念体系。进一步地,对非淹没双体丁坝和淹没双体丁坝作用尺度进行定量化研究,并在此基础上探讨不同作用尺度之下非淹没丁坝群和淹没丁坝群累积效应机理。论文完成的主要工作和取得的成果如下： (1)在水槽试验获得实测数据资料的基础上,选取三种紊流模型——标准k-ε模型、雷诺应力模型(RSM)和大涡模拟(LES),并且每种紊流模型之下自由表面边界分别采用刚盖假定和VOF模型两种处理方法,将6种数学模型分别应用于非淹没丁坝群和淹没丁坝群流场模拟中,综合考虑模型计算结果与水槽试验实测数据之间的吻合程度以及模型的计算时间,得出不同研究目的之下非淹没丁坝和淹没丁坝流场数值模拟所适合的紊流模型及自由表面边界条件。 (2)根据丁坝流场数值模拟模型优选的结论并结合实际计算条件,确定非淹没丁坝流场数值模拟选用标准k-ε模型和刚盖假定所组成的数学模型,淹没丁坝流场数值模拟选用标准k-ε模型和VOF模型所组成的数学模型,以此作为工具,对不同间距之下非淹没双体丁坝和淹没双体丁坝的流场进行比较分析,提出三种非淹没丁坝群作用尺度划分准则——基于大尺度涡不相重叠、基于双丁坝断面流速分布相似和基于下游丁坝断面流速分布恢复,通过对三种划分准则的定性分析比较,分别得出三种划分准则的优缺点及适用范围；同时,提出一种淹没丁坝群作用尺度划分准则——基于下游丁坝断面流速分布恢复,通过定性分析,得出该划分准则的优缺点及适用范围。 (3)通过量纲分析分别获得非淹没双体丁坝和淹没双体丁坝间距阈值的影响因素,并据此拟定数值试验工况；采用数值模拟的手段分别开展非淹没双体丁坝和淹没双体丁坝作用尺度量化研究,得出三种非淹没丁坝划分准则之下丁坝间距阈值的经验公式,定量比较三个公式的计算结果发现,基于大尺度涡不相重叠划分准则的计算结果偏小,后两者计算结果相当,机理分析表明,后两者本质相同但适用范围差异较大,前者是非淹没丁坝作用尺度判断的必要非充分条件；同时,获得淹没双体丁坝划分准则之下间距阈值的经验公式,并进一步对非淹没双体丁坝和淹没双体丁坝间距阈值进行横向定量比较。 (4)最后,以非淹没双体丁坝三个间距阈值经验公式为基础,分别对三种作用尺度之下非淹没丁坝群水流结构、水流时均流速以及紊流强度等要素的累积效应机理进行探讨,通过对比分析发现,不同作用尺度之下非淹没丁坝群水流要素的累积效应有所不同,随着相邻丁坝间距增大作用尺度增大,累积影响最先消失的是水流结构,其次是水流时均流速,最后是紊流强度；以淹没双体丁坝间距阈值经验公式为基础,分别对两种作用尺度之下淹没丁坝群水面高度、水流时均流速以及紊流强度等要素的累积效应机理进行探讨,研究发现随着丁坝个数的累加,淹没丁坝群水面高度和水流时均流速的累积变化规律相反并且累积影响同时消失,而紊流强度仍然是其中最难恢复的水流要素。
[Abstract]:The dam is a kind of common river - involved building , which is widely used in river engineering , flood control project , waterway regulation project and river beach reclamation project .

In this paper , a flume experiment is carried out in the construction experiment hall of Zhejiang University to obtain the experimental data of the flow field of an array of tees . Then , three different methods are selected to solve the numerical simulation of the flow field of the dike swarm . On the basis of the previous study , a numerical flume is adopted to study the numerical simulation of the flow field of the non - submerged spur and submerged spur dike .

( 1 ) Based on the measured data of flume test , three turbulence models _ standard k - 蔚 model , Reynolds stress model ( RSM ) and large eddy simulation ( LES ) are selected , and six mathematical models are applied to the flow field simulation of non - submerged spur dike and submerged spur dike respectively .

( 2 ) According to the preferred conclusion of the numerical simulation model of the flow field of the dike and combining with the actual calculation conditions , the numerical simulation of the flow field of the non - submerged spur dike is determined by using a mathematical model consisting of a standard k - 蔚 model and a VOF model . The numerical simulation of the submerged spur dike is based on a standard k - 蔚 model and a VOF model .
At the same time , this paper presents a criterion for the scale division of submerged spur dike swarm , which is based on the distribution of the flow velocity distribution of the downstream dam section . Through qualitative analysis , the advantages and disadvantages and application range of this criterion are obtained .

( 3 ) the influence factors of the distance threshold of the non - submerged double dam and the submerged double dam are obtained through dimensional analysis , and the numerical test working condition is developed accordingly ;
The numerical simulation method is used to quantify the effect of non - submerged double - body dike and submerged double - body dike , and the empirical formula of three formulas is obtained . The results show that the calculation results of three formulas are small and the results are quite different . The results show that the former is the same but the application range is different . The former is the necessary and non - sufficient condition for judging the function scale of the non - submerged spur dike .
At the same time , the empirical formula of spacing threshold under the criterion of submerged double - body dike is obtained , and the horizontal quantitative comparison between the non - submerged double - body dike and submerged double - dam spacing threshold is further carried out .

( 4 ) Finally , based on the empirical formula of the three space threshold values of the non - submerged double - body tee dam , the cumulative effect mechanism of the flow structure , the flow velocity and the turbulence intensity of the non - submerged spur dike under the three action scales are discussed . Through the comparative analysis , the cumulative effect of the flow elements of the non - submerged spur dike under different action scales is different .
Based on the empirical formula of the distance threshold of the submerged double - body dike , the cumulative effect mechanism of the factors such as the height of the surface of the submerged spur dike , the velocity of the flow and the intensity of the turbulent flow under the two action scales are discussed . The results show that the cumulative effect of the flow velocity and the cumulative effect of the velocity of the water at the surface of the submerged spur dike are opposite and the cumulative effect disappears along with the accumulation of the number of the dike , and the turbulence intensity is still the most difficult to recover the water flow element .
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV863

【参考文献】