摘要
丁坝是水利工程中最为常见的水工建筑之一,丁坝区产生的回流将引起复杂的河道流速分布和泥沙输移过程,对于船舶航行和水利工程有着重要的影响。现有丁坝水沙特性研究多集中于数学模型方面,现场实测资料和模型实验等直接观察得到的数据非常有限。本文通过室内大型水槽进行的实体模型实验,模拟水流在连续丁坝区的回流形态。通过粒子跟踪测速技术对全流场的水流流速、分布进行了测量,记录流量和水深过程,并对水流回流特性进行了分析。实验结果表明:(1)采用电磁流量计量测结果准确,水深变化过程稳定;(2)丁坝区的回流存在纵向零流速线,将其沿横向划分为主流区、回流正区和回流负区,沿纵向划分为增流区和减流区,横向障碍物前存在次生回流;(3)回流流量呈现中心稳定两侧迅速增减,最大可达上游来流量的50%。实验成果可为更加深入地研究丁坝区回流和泥沙冲淤特性提供可靠的数据,为数值模拟提供详细的验证资料,进而对航道设计及河岸维护等工程实际提供科学的支撑作用。
Spur dikes, a hydraulic structure frequently used in river engineering, generate flow circulations and bring about complication in flow velocity distribution and sediment transport, significantly impacting navigation and local water environment. Most previous studies focused on mathematical modeling of the flow and sediment transport behaviors, while its field or laboratory measurements are lacking. In this study, we conducted a laboratory experiment on a train of model spur dikes in a wide open channel built in a large-scale flume to simulate the flow circulations and their effects on the channel flow. Full-field velocity was measured using a particle tracking velocimetry (PTV) and time histories of discharge and flow depth were recorded to analyze the characteristics of circulations. The results indicate that: (1) the electromagnetic flowmeter (EMF) gives accurate measurement of discharge and the flow depth varies smoothly as expected; (2) a circulation zone can be divided into three regions: a backflow region, a forward flow region, and a mainstream region; (3) the backflow rate of a recirculation zone can reach up to 50% of the inflow. This study provides a set of reliable data that would help further study of the flows and sediment transport around spur dikes and be useful for verification of numerical models.
作者
韩晗
张曼
林斌良
周建军
HAN Hart ZHANG Man LIN Binliang ZHOU Jianjun(State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084)
出处
《水力发电学报》
EI
CSCD
北大核心
2017年第10期84-92,共9页
Journal of Hydroelectric Engineering
基金
水沙科学与水利水电工程国家重点实验室科研课题项目(2015-KY-2)
关键词
河流动力学
丁坝
模型实验
回流区
river dynamics
spur dikes
physical model experiment
circulation zone