溢洪道泄槽不同弯道条件与导流墙布置方案水流特性试验研究

发布时间：2018-06-18 10:13

本文选题：弯道水流 + 导流墙　；参考：《山东农业大学》2014年硕士论文

【摘要】：溢洪道是水库枢纽工程的重要组成部分,泄槽段是控制段(过堰或闸)与消能防冲设施段的连接部分。在实际工程中,由于受地形、地质等方面的限制,往往需要在泄槽段设置弯道。由于弯道的环流特性,急流通过弯道时,水流流态恶化。为消除弯道水流的不利影响,设置导流墙是工程措施之一。本文以模型试验为基础,对多种组合的弯道水流特性进行研究,研究的内容和结论如下： (1)弯道设置导流墙后水流特性分析溢洪道弯道设置导流墙情况下弯道水流特性与不设导流墙基本一致。溢洪道弯道水流(纵横向)仍然不均匀,凹岸和凸岸波峰和波谷交替出现,存在明显的菱形波,一直向下游传播。弯道底坡和轴线半径对凹岸水深沿纵向变化有明显的影响：底坡越陡,凹岸最大水深就越小；弯道轴线半径越大,凹岸最大水深就越小。弯道各横断面凹凸岸水深均有明显变化,凹岸水深大于凸岸水深,形成明显的水面横比降。水流沿横向有局部的壅高和降低,水流沿横向不均匀。弯道底坡和弯道轴线半径对横断面水面差存在影响：弯道底坡越陡,各横断面最大水面差越大；轴线半径越小,各横断面最大水面差越大。减小弯道底坡、增大弯道半径可以减小弯道出口断面水位差,使弯道下游水流更加均匀。设置导流墙后,导流墙对弯道水流进行了分割,分割为左右两个水槽。在小流量时(即水位在导流墙以下时)横比降较小,导流墙两侧水位有较大水位差,导流墙右侧水深明显高于导流墙左侧水深；大流量时(即水位在导流墙以上时)横比降较大,导流墙两侧水位大致相平。 (2)弯道设置导流墙后对水流的改善效果分析不同流量、泄槽底坡、弯道轴线半径、导流墙条数等对弯道水流改善效果有明显的影响。引入了横断面水面差降低率和横断面水流均匀度评价水流改善效果。试验结果表明流量越小,导流墙对弯道水流的改善效果越好,即当导流墙将弯道水流完全分开时,导流墙对弯道水流横断面水面差的改善效果最好；弯道底坡越缓,导流墙对弯道水流的改善效果越好；弯道轴线半径越大,导流墙对弯道水流的改善效果越好；导流墙条数越多,导流墙对弯道水流的改善效果越好。设置导流墙后流速沿纵向变化更加稳定,并且导流墙条数越多流速沿程越稳定。
[Abstract]:Spillway is an important part of reservoir hub project, and the sluice section is the connecting part between control section (through Weir or sluice) and energy dissipation and scour prevention facility. In practical engineering, due to the limitation of topography, geology and so on, it is often necessary to set up bends in the channel section. Because of the circulation characteristics of the bend, the water flow state deteriorates when the jet flows through the bend. In order to eliminate the adverse effect of bend flow, the installation of diversion wall is one of the engineering measures. Based on the model test, this paper studies the flow characteristics of various combinations of bends. The contents and conclusions of the study are as follows: 1) the flow characteristics of spillway with diversion wall are basically consistent with those without diversion wall. The flow of spillway bend (longitudinal and horizontal) is still uneven, the peak and trough of the concave and convex banks appear alternately, and there are obvious rhombic waves which propagate downstream. The bottom slope and axis radius of the bend have obvious influence on the variation of water depth along the longitudinal direction: the steeper the bottom slope, the smaller the maximum water depth of the concave bank, and the smaller the radius of the axis of the bend, the smaller the maximum water depth of the concave bank. The depth of the concave bank is larger than that of the convex bank, which results in obvious water surface ratio drop. The water flow along the lateral side has local blockage and decrease, and the flow along the transverse uneven. The influence of bottom slope and axis radius of bend on the water surface difference of cross section is as follows: the steeper the bottom slope of the bend, the greater the maximum water surface difference of each cross section; the smaller the radius of axis, the greater the maximum water surface difference of each cross section. Reducing the bottom slope of the bend and increasing the radius of the bend can reduce the water level difference at the outlet of the bend and make the downstream flow of the bend more uniform. After setting the diversion wall, the bend flow is divided into two flumes. When the water level is below the diversion wall, the transverse ratio is smaller, the water level on both sides of the diversion wall is larger, and the water depth on the right side of the diversion wall is obviously higher than that on the left side of the diversion wall. At large discharge (that is, when the water level is above the diversion wall), the transverse ratio decreases greatly, and the water level on both sides of the diversion wall is approximately equal. The radius of the axis of the bend and the number of the diversion wall have obvious influence on the improvement effect of the bend flow. The reduction rate of cross section water surface difference and the uniformity of cross section flow are introduced to evaluate the effect of water flow improvement. The test results show that the smaller the flow rate, the better the improvement effect of the diversion wall on the bend flow, that is, when the diversion wall completely separates the bend flow, the better the effect of the diversion wall on the cross-section water surface difference of the bend flow is, and the slower the bottom slope of the bend is, The better the effect of the diversion wall on the bend flow is, the bigger the radius of the axis of the bend is, the better the improvement effect of the diversion wall is on the bend flow; the more the number of the diversion wall is, the better the improvement effect of the diversion wall is on the bend flow. The velocity variation along the longitudinal direction is more stable after setting the diversion wall, and the more the strip number of the diversion wall, the more steady the velocity along the course.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV135.2

【参考文献】