高术仙¹, 徐海珏^1,2, 白玉川^1,2
AuthorsHTML:高术仙¹, 徐海珏^1,2, 白玉川^1,2
AuthorsListE:Gao Shuxian¹, Xu Haijue^1,2, Bai Yuchuan^1,2
AuthorsHTMLE:Gao Shuxian¹, Xu Haijue^1,2, Bai Yuchuan^1,2
Unit:1. 水利工程仿真与安全国家重点试验室(天津大学)，天津 300072；2. 天津大学河流海岸工程泥沙研究所，天津 300072
Unit_EngLish:1．State Key Laboratory of Hydraulic Engineering Simulation and Safety (Tianjin University), Tianjin 300072, China
2．Institute for Sedimentation on River and Coastal Engineering, Tianjin University, Tianjin 300072, China
Abstract_Chinese:床面剪应力诱发了水流垂向上流速分布不稳定性, 压力和向心力不均则促使水流形成了弯道二次流．通过试验, 研究了近临界弯曲比率(R/B＝3)条件下, 小宽深比(B/H＝2)水槽中水流变化及泥沙输移特性．研究结果表明：二次流强度最大值出现在弯顶区域, 床面剪应力最大值出现在弯顶偏凸岸一侧．弯道床面附近, 不同层面上的剪应力最大值, 从上游到下游先增大后减小; 不同平面动力轴线随层面的高度增加而向凹岸偏离．二次流在不同断面形成不同的涡核, 在弯道入口附近产生分离而在弯道下游逐步发展, 涡核合并, 二次流强度在弯顶区达到最大值．最后对二次流和床面剪应力作用下的床面形态结果进行分析．
Abstract_English:Bed shear stress mightily induces the instability of velocity distribution in vertical direction，and non-uniform stress and centripetal force of water flow cause secondary flow in channel bends. In this study，the changes of water flow and sediment transport characteristics in flume under a small wide depth ratio(B/H＝2)and the near-critical curvature ratio(R/B＝3)were investigated. The results show that the maximum secondary ?ow strength is located at the apex of bend，and bed shear stress reaches its maximum at the apex of upstream，which is closer to the convex bank. On the other hand，near the bed，the maximum of shear stress at different levels firstly increases and then decreases from the first half of channel bend to the second half. At different levels，the flow dynamic axis skews to concave with the increase of level height. As for the secondary flow in channel bends，various vortex cores form in different sections，which will firstly be separated near the entrance of channel bend，then gradually evolve toward the downstream，and merge together in the end. Ultimately，the analyses of the bed results were presented，considering the interactions between secondary flow and bed shear stress.
Keyword_Chinese:180° 强弯水槽; 近临界弯曲比率; 二次流; 床面剪应力; 雷诺应力方法; 紊动能方法
Keywords_English:180° sharp bend; near-critical curvature ratio; secondary flow; bed shear stress; Reynolds shear stress method; TKE method

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