明渠均匀流Q结构分布及运动特性  

Distribution and motion characteristics of Q-events for open-channel uniform flow

作　　者：杨胜发[1] 张鹏[2] 胡江[1] 李文杰[1] 陈阳[2] 

机构地区：[1]重庆交通大学国家内河航道整治工程技术研究中心,重庆400074 [2]重庆交通大学水利水运工程教育部重点实验室,重庆400074

出　　处：《水科学进展》2016年第3期430-438,共9页Advances in Water Science

基　　金："十二五"国家科技支撑计划资助项目(2011BAB09B01);国家自然科学基金资助项目(51209241)~~

摘　　要：为了解明渠均匀流湍流Q结构(Quadrant events)第一象限事件(Q1)、第二象限事件(Q2)、第三象限事件(Q3)和第四象限事件(Q4)的时均与瞬态运动特性,使用高频粒子成像测速系统对3种明渠湍流二维瞬时流速矢量场进行测量,统计分析明渠湍流脉动流速场中Q结构的雷诺应力、发生频率、占据测量区域面积率以及Q结构与涡结构运动关系。结果表明:Q1与Q3结构时均特性相似,具有发生频率低、面积占据量少、负瞬时脉动动量通量小等特点;而Q2与Q4结构时均特性与之相反,且Q4结构发生频率沿水深增加而逐渐增多至0.8H附近达到最大,Q2结构发生频率在壁面区域为最大,沿水深增加而减小。明渠瞬态运动特性主要表现为水面区造成Q4结构向下运动,挤压、推进、爬升床面区的Q2结构伴随其自身形变的瞬态发展过程。To understand the time-averaged transient motion characteristics of Q-events for open-channel uniform flow （first-quadrant （ Q1 ）, second-quadrant （ Q2 ）, third-quadrant （ Q3 ）, fourth-quadrant （ Q4 ） ）, a high-frequency particle image velocimetry system was used to measure three two-dimensional instantaneous velocity vector fields of tur- bulent open-channel flows. The Reynolds stress, occurrence frequency, and measured area of Q-events in fluctuating velocity fields in open-channel flow and the relationship between Q-events and vortex motions were statistically ana- lyzed. The results indicated that the time-averaged characteristics of Q1 and Q3 were similar, with low occurrence fre- quency, small area, and negative instantaneous fluctuating momentum flux. The time-averaged characteristics of Q2 and Q4 were opposite to those of Q1 and Q3. In addition, the occurrence frequency of Q4 increased with water depth to reach a maximum at about 0.8H, whereas the occurrence frequency of Q2 reached a maximum near the walls and decreased with water depth. The transient motion characteristics of the open channel were evident mainly in the down- stream movement of Q4 resulting from the water surface area and in the extrusion, uplift, and climbing behavior of the Q2 structure in the bed region accompanying the transient development process of its deformation.

关 键 词：明渠 湍流结构 雷诺应力 Q结构 时均特性 瞬态运动 

分 类 号：TV131[水利工程—水力学及河流动力学]