光滑矩形明渠二次流特性研究  

Study on characteristics of secondary flows in smooth rectangular open channel

作　　者：景思雨 杨文俊[1] 陈越 JING Siyu;YANG Wenjun;CHEN Yue(High speed water flow laboratory,Changjiang River Scientific Research Institute,Wuhan 430014;Department of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210098)

机构地区：[1]长江科学院高速水流实验室,武汉430014 [2]河海大学水利水电学院,南京210098

出　　处：《水力发电学报》2020年第1期12-20,共9页Journal of Hydroelectric Engineering

基　　金：国家重大科研仪器研制项目(51527809).

摘　　要：明渠中二次流的存在影响了流速和能量的分布,本文利用高分辨率粒子图像测速系统(PIV),对光滑明渠中二次流的特性进行研究。考虑到明渠紊流具有对称性,对二分之一水槽内的水流参数进行了测量。由于宽深比的变化对二次流有直接影响,取宽深比从3.75到7.5,研究急流条件下二次流结构和强度的变化,以及雷诺应力沿垂线分布的变化规律。结果表明:横断面内存在多个二次流涡结构,其个数和强度受到宽深比的影响;紊动能分布和二次流之间关系密切;流向速度分布存在最大流速下移现象,下移点位置和宽深比以及测线到壁面的距离有关,符合经验公式计算结果;水槽中心处雷诺应分布不受宽深比的影响,但是受到流速梯度的影响。Occurrence of secondary flows in an open channel greatly affects its distributions of flow velocity and energy,and its aspect ratio has a direct impact on the secondary flows.This study uses a high-resolution particle image velocimetry to investigate the behaviors of secondary flows in a straight channel with different aspect ratios,through measuring flow parameters at the sections of one half of the flume by considering flow symmetry.We focus on the influence of aspect ratio on the structure and strength of secondary flows under supercritical conditions;and conduct experimental tests on a narrow,deep chute,using the channel aspect ratio in the range of 3.75-7.5.The results indicate that(1)several secondary cells exist at the cross sections with their total number increasing with aspect ratio,and aspect ratio exerts a great influence on the number and strength of secondary flow.(2)Turbulence intensity and velocity distribution are closely related to secondary flow behaviors.(3)A dip phenomenon occurs in the distribution of streamwise velocity,and the location of velocity peak depends on aspect ratio and the distance to the sidewall.(4)Reynolds stress distribution around the cross section center shows no significant difference when the aspect ratio is changed,but it is affected by the gradient in streamwise velocity.

关 键 词：明渠紊流 高分辨率PIV 二次流 宽深比 雷诺应力 

分 类 号：TV143[水利工程—水力学及河流动力学]