泄洪洞突扩突跌掺气设施水流特性研究

发布时间：2018-09-14 11:09

【摘要】：水利工程中的泄水建筑物,包括溢流坝、溢洪道、泄洪洞等,当下泄水流速度达到一定程度,即所谓的高速水流时,由于水流速度高,压强降低,当水流压强降低到一定程度后,水流中将产生空泡形成水流空化。空化水流由低压区流到高压区,伴随着空泡的生产、发展和溃灭,如果空泡的溃灭发生在流道固壁附近时,其产生的微射流和辐射冲击波作用在固壁上有可能造成空蚀破坏。掺气减蚀措施可以减免高速泄水建筑物的空蚀破坏。有压洞出口采用突扩突跌掺气设施,会同时形成底空腔及侧空腔,获得较好的掺气减蚀效果,对建筑物底板及侧墙均起到良好的保护作用。在有压洞出口变为名流条件下,通过对突扩突跌掺气设施水工模型进行不同突扩宽度、跌坎高度、下游坡度、来流条件下的模型试验,可以初步确定跌坎高度、突扩宽度、下游坡度等参数对底、侧空腔特性及水流掺气的影响作用。本文采用模型试验的方法对突扩、突跌掺气设施的水力特性进行对比分析,通过试验研究,改变不同突扩、突跌体型尺寸,形成不同突扩比与突跌比的组合,以及改变不同的流量,来对比分析各方案、各工况下掺气设施后的水流流态、压力、水流空化数、掺气浓度的沿程分布情况及掺气空腔特性等水力要素的特征；利用多元函数拟合方法对试验测量数据进行分析,得到与本次试验体型类似的计算侧空腔与底空腔的经验公式,可为水力条件和边界条件相似的工程或进一步的试验或理论研究提供参考。本文采用数值模拟方法,利用Fluent等计算软件、Eulerian双流体模型计算方法,计算得出与模型试验相同边界及水力条件下相应方案、工况的水力特性参数。并将这些特性参数与模型试验实测所得的水力特性参数进行对比,以检验数值模拟方法的正确性及计算精度。本论文揭示了突扩突跌侧掺气和底掺气两种掺气形式的机理的差异、相互影响和共同作用规律,研究成果对提高突扩突跌掺气设施全断面掺气减蚀效果,为该种掺气减蚀设施的更好地应用提供了有益的理论依据。
[Abstract]:In water conservancy projects, the drainage structures, including spillway, flood discharge tunnel, etc., when the downflow velocity reaches a certain level, that is, when the so-called high speed water flow, the pressure is reduced because of the high flow velocity. When the flow pressure is reduced to a certain extent, cavitation will occur in the flow. Cavitation flow flows from the low pressure region to the high pressure area, with the production, development and collapse of the cavitation bubble. If the cavitation collapse occurs near the wall of the channel, the micro jet and radiation shock wave may cause cavitation damage on the solid wall. Aeration erosion reduction measures can reduce cavitation erosion damage of high speed drainage structures. With the sudden expansion and falling aeration at the outlet of the pressure hole, both the bottom cavity and the side cavity will be formed, and the effect of aeration on corrosion reduction will be better, which will play a good protective role on both the floor and the side wall of the building. Under the condition that the outlet of the pressure tunnel becomes a celebrity, through the model tests on hydraulic models of sudden expansion, sudden fall in aeration facilities, different width of sudden expansion, height of fall ridge, downstream slope, and condition of incoming flow, the height of falling ridge and the width of sudden expansion can be preliminarily determined. The influence of the downstream slope and other parameters on the bottom, side cavity characteristics and flow aeration. In this paper, the hydraulic characteristics of sudden expansion and sudden fall aeration facilities are compared and analyzed by using the method of model test. Through the experimental study, the size of different sudden expansion and sudden fall type is changed, and the combination of different sudden expansion ratio and sudden drop ratio is formed. And changing different flow rate to compare and analyze the characteristics of hydraulic factors such as flow state, pressure, cavitation number of water flow, distribution of aeration concentration along the path and characteristics of aeration cavity, etc. By means of multivariate function fitting method, the experimental data are analyzed, and the empirical formulas for calculating the lateral cavity and the bottom cavity are obtained, which are similar to the shape of the experiment. It can be used as a reference for engineering with similar hydraulic and boundary conditions or for further experiments or theoretical studies. In this paper, the numerical simulation method is used to calculate the hydraulic characteristic parameters of the corresponding scheme under the same boundary and hydraulic conditions as the model test by using the calculation method of the Eulerian two-fluid model with Fluent et al. In order to verify the correctness and accuracy of the numerical simulation method, these characteristic parameters are compared with the hydraulic characteristic parameters measured in the model test. In this paper, the mechanism difference, mutual influence and common action law of two kinds of aeration forms of sudden expansion, falling side aeration and bottom aeration are revealed. The research results can improve the effect of whole section aeration to reduce corrosion of sudden expansion sudden fall aeration facilities. It provides a useful theoretical basis for the better application of the aerated corrosion abatement facility.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV135.2;TV131.3

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