马岭水利枢纽工程导流与泄洪建筑物体型研究

发布时间：2018-03-09 02:37

本文选题：导流隧洞　切入点：表孔挑流　出处：《西北农林科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：马岭水利枢纽工程地形狭窄,下游消能空间有限,水力学问题较为复杂。施工导流期,导流洞的安全运行影响工程度汛与建筑物施工,进口体型对过流水流的流态有一定影响,流态变化又直接决定导流洞内水力参数的变化,因此有必要对进口体型进行研究。枢纽运行期,坝身泄水孔大流量泄洪时容易存在向心集中问题,而消能工体型不同,泄水孔水舌的能量分布与下游的冲刷深度就存在差异。为研究消能工体型对流场的影响,优化导流与泄水建筑物布置形式,本文在模型试验的基础上,利用数值模拟分别计算了导流洞与坝身泄水孔在不同体型下的流场分布。首先,利用FLUENT软件对导流洞流场进行数值模拟,计算得到的压力等流场数据与模型试验结果基本吻合。通过其进口体型的研究,发现,如果进口顶板曲线衔接顺畅,就会对减小水流脱壁现象有利,因此,边界连接处的设计应尽量满足相切的原则,以减小拐点的影响;进口截面的形状对水流流态的影响相对更加显著,进口截面采用矩型断面后,相比城门洞型断面,水流脱壁现象减弱,能量损失小,同时能够降低门槽位置空化发生的可能性;综合不同体型的研究,比较后认为,导流洞采用矩型进口更有利于导流泄洪。其次,利用FLOW-3D软件对坝身泄水孔过流流场进行数值模拟,数值计算结果基本能够反映流场信息。研究发现,溢流式泄水孔大单宽泄洪情况下,窄缝消能工水舌扩散能力有限,下泄能量集中,而采用高差动坎消能工后,水舌能够实现纵向拉开和横向扩散,保证下泄水流能量的分散。进一步分析高差动坎消能工的消能机理可得,这一消能工体型下,入水水舌形态多样,下游动水垫的作用较强,下泄水股能量耗散量大;河床受到的时均冲击压力较小而且分散,脉动(压强波动)能量的分布也同样比较分散,频谱分析发现,其能量大部分集中在低频区域。总之,高差动坎消能工在大单宽泄洪条件下,消能效果较为显著,而且联合泄洪时其优势仍能得到较好地发挥。
[Abstract]:Maling water conservancy project has narrow topography, limited downstream energy dissipation space and complex hydraulic problems. During the construction diversion period, the safe operation of diversion tunnel affects the flood and building construction of the project, and the type of inlet has a certain influence on the flow pattern of the overflowing water flow. The change of flow state directly determines the change of hydraulic parameters in the diversion tunnel, so it is necessary to study the inlet shape. During the period of the hub operation, the problem of concentric concentration is easy to exist in the large discharge flood discharge of the discharge hole of the dam body, but the type of energy dissipator is different from that of the energy dissipator. In order to study the influence of energy dissipation on the flow field of energy dissipator and optimize the layout of diversion and drainage structures, this paper is based on the model test. Numerical simulation is used to calculate the flow field distribution of diversion tunnel and dam drainage hole in different shapes. Firstly, the flow field of diversion tunnel is numerically simulated by FLUENT software. The calculated data of pressure equal flow field are in good agreement with the results of the model test. Through the study of the inlet shape, it is found that if the inlet roof curve is connected smoothly, it will be beneficial to reduce the phenomenon of water flow dewalling. The design of boundary junction should satisfy the principle of tangent as far as possible to reduce the influence of inflexion, the shape of inlet section has more significant influence on the flow state of water. The phenomenon of water flow dewalling is weakened, the energy loss is small, and the possibility of cavitation in the gate groove position can be reduced at the same time. According to the study of different shapes, it is concluded that the rectangular inlet of the diversion tunnel is more favorable for the diversion and flood discharge. The numerical simulation of the flow field in the outlet of dam body is carried out by using FLOW-3D software, and the numerical results can basically reflect the information of the flow field. It is found that the diffusion capacity of the narrow gap energy dissipator is limited under the condition of large single width spillway of overflow discharge hole. When the energy is concentrated, the water tongue can be spread vertically and horizontally, and the energy dissipation mechanism can be obtained by further analyzing the energy dissipation mechanism of the energy dissipator of the high differential sill, and the energy dissipation mechanism can be obtained under this type of energy dissipator, and the mechanism of energy dissipation can be obtained by further analyzing the energy dissipation mechanism of the energy dissipator. The shape of the inlet water tongue is diverse, the action of the downstream dynamic water cushion is stronger, the energy dissipation of the outlet is large, the average impact pressure on the riverbed is small and dispersed, and the energy distribution of the pulsation (pressure fluctuation) is also dispersed. The spectrum analysis shows that, Most of its energy is concentrated in the low frequency region. In a word, under the condition of large single width flood discharge, the energy dissipation effect of high differential bar energy dissipator is more remarkable, and its advantages can still be well brought into play when combined flood discharge.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV551.1;TV65

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