【作者】 褚克坚；

【导师】 王惠民； 华祖林；

【作者基本信息】 河海大学 ， 环境工程， 2006， 博士

【摘要】 通过物理模型试验,本文分别对直道、45°、90°和180°弯段温差剪切分层流运动特性进行研究,并建立直道和弯段分层流数学模型,通过数值试验的方式,进一步细化地分析分层流交界面的紊动特性。主要内容有: (1) 对分层流运动特性的研究方法和前人主要研究成果进行了较为全面的总结,指出借助现代试验量测手段与数学模型研究直道与弯段分层流的必要性与可行性。 (2) 建立直道水槽温差剪切分层流物理模型试验系统,进行冷热水多种不同流量的组合试验,应用ADV、数字温度计等量测技术,研究直道分层流时均特性和紊动特性,揭示分层流紊动掺混机理,并作分层流稳定性分析。 (3) 分别建立45°、90°和180°不同弯段水槽温差剪切分层流物理模型试验系统,进行冷热水多种不同流量的组合试验,应用ADV、数字温度计等量测技术,研究不同弯段分层流时均特性和紊动特性,探寻不同弯段对分层流的掺混与稳定性的影响。 (4) 建立基于矩形网格的浮力修正κ-ε各向异性立面二维有限体积计算模式,模拟直道水槽温差剪切分层流。计算结果表明,现有模型的浮力修正只是针对特定流型建立的经验关系,仅适合于模拟完全分层水体。 (5) 建立基于矩形网格的二阶矩Reynolds应力三维有限体积计算模式,成功模拟直道水槽温差剪切分层流,并采用数值试验的方法对直道水槽分层流交界面紊动特性做进一步细化研究。 (6) 建立基于无结构网格的二阶矩Reynolds应力三维有限体积计算模式,成功模拟180°弯段水槽温差剪切分层流,并采用数值试验的方法对180°弯段水槽分层流交界面紊动特性做进一步细化研究。更多还原

【Abstract】 The dynamic characteristics of thermally stratified shear flow in straight and curved flumes with 3 bending angles of 45° , 90° and 180° have been experimentally studied respectively. The mathematical models applying in straight and curved flumes were established. The turbulent characteristics at the interface of stratified shear flow have been analyzed ulteriorly by numerical experimental investigation. The main conclusions include as follows:1. The advances in the research of the characteristics of stratified flow are reviewed overall. The necessary and feasibility of the application of precise instruments and mathematical models in the research of stratified flow in straight and curved flume are pointed out.2. The straight laboratory flume of thermally stratified shear flow has been established. Several experimental test runs with different discharge ratio of warm water to cold water were conducted. With precise instruments such as MicroADV and digital thermometer, the time-averaged and turbulent characteristics of stratified shear flow in the straight flume are researched, and the mechanism of turbulent mixing between warm and cold water layers is discovered. The analysis of stability for stratified shear flow in the straight flume is conducted.3. Three curved flumes with bending angles of 45°, 90° and 180° of thermally stratified shear flow have been established respectively. Several experimental test runs with different discharge ratio of warm water to cold water were conducted. With precise instruments such as MicroADV and digital thermometer, the time-averaged and turbulent characteristics of stratified shear flow in the curved flumes are researched. The bend effect on mixing and stability for stratified shear flow is explored.4. A rectangular grid finite volume algorithm for lateral 2-Dimension anisotropic k-ε model with buoyancy-correction is established. By the calculation for some laboratory stratified shear flow cases in straight flume, it is shown that the buoyancy-correction of the k-ε model is the establishment of experimental relationship between the model and special stratified flow pattern. The anisotropic k-ε model only adapts to simulate the strong stratification, so it’s applicability is poor.5. A rectangular grid finite volume algorithm for 3-dimension second-moment Reynolds stress model is established, and used to simulate the laboratory stratified shear flow cases in straight flume successfully. By numerical experimental investigation, the turbulent characteristics at the interface of thermally stratified shear flow in straight flume are discussed ulteriorly.6. An unstructured grid finite volume algorithm for 3-dimension second-moment Reynolds stress model is established, and used to simulate the laboratory stratified shear flow cases in strong curved flume with bending angle of 180° successfully. By numerical experimental investigation, the turbulent characteristics at the interface of thermally stratified shear flow in strong curved flume with a bending angle of 180° are discussed ulteriorly.更多还原