小宽深比条件下弯道水流特性的试验研究

发布时间：2018-06-17 03:07

本文选题：弯道水流 + 水面横比降　；参考：《工程科学与技术》2017年06期

【摘要】：在弯道水流中,几何参数宽深比对水流的3维运动特性具有重要影响。由于小宽深比(5)河道广泛存在于山区及人工河道中,采用声速多普勒流速仪(ADV)对固定宽度不同宽深比(B/H分别为1.5,2.0,3.0)的U型弯道内水流流速进行了精细测量,并以水面横比降、横向环流、流速重分布、紊动强度与剪切力为研究内容,讨论与分析了该情况下的弯道水流结构。试验结果表明,在小宽深比条件下增加宽深比时:1)水流动力轴线开始向凹岸偏移的位置提前,因而小流速主流线沿着凸岸流动,直到出弯道才开始向凹岸偏移,大流速则更早地向凹岸偏移;2)横向流速在凹岸开始波动的位置依次靠近上游,3种工况中波动位置分别为120°断面、90°断面及60°断面;3)凹岸表层附近出现次生环流的位置依次提前,其位置分别为120°断面、60°断面及30°断面,并且次生环流强度及范围不断增大;4)床面剪切力不断增大。需要指出的是:3种工况的剪切力在弯道入口断面到弯顶断面之间较大,最大剪切力位置均出现在弯道的前半段,可以推断在动床中弯道泥沙在此段的冲刷比较严重;过弯顶断面后,凸岸床面剪切力大于凹岸。试验结果可以有效地反映不同小宽深比参数对弯道水流结构的影响,并为该条件下的弯道泥沙冲淤研究提供参考。
[Abstract]:In the curved flow, the ratio of geometric parameters to depth has an important effect on the three-dimensional motion characteristics of the flow. Due to the existence of small width-depth ratio (5) channel in mountainous area and artificial channel, the flow velocity in U-shaped bend with fixed width and different aspect ratio (B / H = 1.5 / 2. 0 / 3) was measured by using the sound velocity Doppler velocimeter (ADV), and the flow velocity was dropped by the ratio of water surface to side. Transverse circulation, velocity redistribution, turbulent strength and shear force are the main contents of the study. The flow structure of curved channel is discussed and analyzed in this paper. The experimental results show that when the ratio of width to depth is increased at the ratio of width to depth, the position of the axis of flow power begins to shift to the concave bank ahead of time, so that the main flow line of small velocity flows along the convex bank, and does not begin to move to the concave bank until the bend is out. Large velocity shifts to the concave bank earlier.) the position of lateral velocity fluctuating near the top of the concave bank is 120 掳cross section 90 掳section and 60 掳cross section 3 respectively) the position of secondary circulation around the concave bank is earlier in turn, and the position of lateral velocity fluctuation is close to the upper reaches of the concave bank in turn, and the fluctuation position is 120 掳cross section 90 掳section and 60 掳section Xi 3 respectively. Its position is 120 掳section 60 掳section and 30 掳section respectively, and the secondary circulation intensity and range are increasing continuously. It should be pointed out that the shear force of the three working conditions is larger between the entrance section of the bend and the top section of the bend, and the position of the maximum shear force appears in the first half of the bend, so it can be inferred that the erosion of sediment in the bend in the moving bed is serious in this section. The shear force of the convex bank is greater than that of the concave bank. The experimental results can effectively reflect the influence of the parameters of different ratio of width to depth on the flow structure of bends and provide a reference for the study of sediment scouring and silting in bends under these conditions.
【作者单位】：西安理工大学水利水电学院;西安理工大学西北旱区生态水利工程国家重点实验室培育基地;
【基金】：国家自然科学基金资助项目(51579206) 陕西省自然科学基础研究计划资助项目(2015JM5201)
【分类号】：TV133

【相似文献】