| 引用本文: | 刘 明,张升堂,张景洲,等.植被茎秆倾伏角变化对明渠水流结构的影响[J].灌溉排水学报,2021,(8):88-92. |
| LIU Ming,ZHANG Shengtang,ZHANG Jingzhou,et al.植被茎秆倾伏角变化对明渠水流结构的影响[J].灌溉排水学报,2021,(8):88-92. |
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| 摘要: |
| 【目的】分析植被茎秆倾伏角变化对明渠水流结构流态的影响，充分发挥河道水生植被功能以减缓河堤的侵蚀和水土流失的速率。【方法】建立明渠植被水流结构模型将水流液层在空间高度上分为植被层和自由层，在茎秆不同的变形状态下及流量范围内开展试验。【结果】①在同一茎秆倾伏角下，植被层Vv随水深h增加呈增加减少再增加最终趋于稳定的变化规律，自由层平均速度Vs、雷诺数Res、弗劳德数Frs随水深h的增大迅速减小后趋于稳定。②不同茎秆倾伏角下，植被层水力参数Vv、Rev、Frv在空间上表现出各向异性，自由层Vs、Res、Frs随植被倾伏角θ增大而减小，植被淹没临界水深h 存在“滞后”现象。【结论】自由层的水流流速Vs、雷诺数Res、弗劳德数Frs均大于植被层；植被层水流流态为缓紊流，自由层水流流态从急紊流迅速过渡到缓紊流。 |
| 关键词: 倾伏角；植被层；自由层；流态 |
| DOI：10.13522/j.cnki.ggps.2020523 |
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| The Effects of Plant Stem Inclination on Water Flow in Open Channel |
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LIU Ming, ZHANG Shengtang, ZHANG Jingzhou, ZHAO Qingxing, SUN Qiwen, WANG Lei
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College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China
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| Abstract: |
| 【Objective】Most open channels are planted with vegetation to avoid erosion of channel beds and slopes while in the meantime facilitating decontamination of organic and inorganic pollutants in the water. However, the vegetation could detrimentally affect water flow. How the depth and growing direction of the vegetation affect water flow across the channel is an issue not well understood. The objective of this paper is to plug this gap.【Method】A physical model was established to simulate water flow in open channel with the vegetation taken into account. Water in the channel was divided into two layers: A vegetation layer and an overlaid free layer. The impact of the growing direction of the vegetation, characterized by their stem inclination angle, was studied experimentally.【Result】①When the inclination angle of the stems was the same, the water velocity in the vegetation layer, Vv, tended to level off as the water depth in the channel, h, increased. In the free layer, the average velocity, Vs, the Reynolds number Res, Froude number Frs increased asymptotically as h increased. ②We found that Vv, Rev and Frv in the vegetation layer were spatially anisotropic varying with the stem inclination angle, while in the free layer Vs, Res and Frs decreased as the stem inclination angle increased. There was a delay in the critical water depth above which the vegetation was submerged. 【Conclusion】Water velocity Vs, Res and Frs in the free layer were higher than that in the vegetation layer. Water flow in the vegetation layer was slow and turbulent, while in the free layer the water flow was rapid, in a transition from fast turbulence to slow turbulence. Our results can help open channel design on how to reduce erosion of its bed and slope by growing vegetation without risking flooding. |
| Key words: pitching angle; vegetation layer; free water flowing layer; water flow regime |
