| 引用本文: | 刘明潇,王泽众,朱勇杰,等.大型输水隧洞出口扩散段非稳流态研究[J].灌溉排水学报,2023,42(12):107-116. |
| LIU Mingxiao,WANG Zezhong,ZHU Yongjie,et al.大型输水隧洞出口扩散段非稳流态研究[J].灌溉排水学报,2023,42(12):107-116. |
|
| 摘要: |
| 【目的】研究水流从有压隧洞到无压明渠扩散段过渡时非稳流态产生机理与改善措施。【方法】本文依据流动相似原理与边界层控制理论，以某大型输水倒虹吸出口过渡段为例，通过水力模型试验分析了扩散段边界层分离及衍生的回流干扰、主流不稳、水流波动特性，研究了不良流态引发的三类附加紊动效应。【结果】①扩散段边界层分离使大量漩涡被主流卷吸，产生附加能耗、衍生波叠加，干扰扩散段平稳过流。②在扩散段增设导流墩抑制了边界层分离，消除合流区涡旋脱落与旁侧回流，消波率达45%~70%，扩散段末端波动强度由1.11 m降为0.20 m；理顺了扩散段流路。【结论】在扩散段设置导流墩的消涡降波作用明显，B型导流墩具有更好的流态改善与能耗降低效果，流速分布沿程调整均衡。 |
| 关键词: 扩散段；边界层分离；脱落涡；衍生波；流线型；导流墩 |
| DOI：10.13522/j.cnki.ggps.2023284 |
| 分类号: |
| 基金项目: |
|
| Unsteady Flow in Diffusion Section at the Outlet of Large Water Conveyance Tunnel |
|
LIU Mingxiao, WANG Zezhong, ZHU Yongjie, HU Hao, WANG Pengtao, SUN Dongpo
|
|
1. Research Center for Port, Channel and Ocean Development, North China University of Water Resources and Electric Power, Zhengzhou 450046, China; 2. Yellow River Conservancy Technical Institute, Kaifeng 475004, China
|
| Abstract: |
| 【Objective】The inverted siphon tunnel in big long-distance open channel spanning across a river is a critical hydraulic infrastructure. Investigating the mechanisms and strategies for addressing the unsteady flow during transition from the pressurized tunnel to the non-pressurized diffusion section of the open channel is essential to safeguarding water delivery and optimizing flow capacity.【Method】Using the principles of flow similarity and boundary layer control theory, this study focuses on the transition section at a large water transfer siphon outlet. Through hydraulic model testing, it examines the boundary layer separation, derived backflow interference, mainstream instability, and flow fluctuations in the diffusion section. We also investigate three additional turbulent effects resulting from unfavorable flow patterns.【Result】① The boundary layer separation in the diffusion section leads to the entrainment of a significant number of vortices by the main flow, resulting in an increased energy consumption and the superposition of derived waves. These phenomena disrupt the smooth flow in the diffusion section. ② Introducing diversion piers in the diffusion section effectively suppresses boundary layer separation, eliminates vortex shedding, and mitigates side backflow in the confluence area. This leads to a substantial improvement in wave dissipation, reducing wave intensity at the end of the diffusion section from 1.11 meters to 0.2 meters. Furthermore, it straightens the flow path within the diffusion section.【Conclusion】Installing diversion piers in the diffusion section is highly effective in eliminating vorticity and reducing wave interference. Specifically, B-type diversion piers prove to be superior in optimizing flow patterns and reducing energy consumption while ensuring a well-balanced flow velocity distribution. These research findings hold significant practical value for design and renovation of large-scale water transfer projects. |
| Key words: diffusion region; boundary layer separation; shedding vortex; derived wave; streamliner; diversion pier |
