【作者】 刘文；

【导师】 贺昌海；

【作者基本信息】 武汉大学 ， 水工结构工程， 2019， 硕士

【摘要】 施工导流是贯穿水电工程施工全过程中所特有的一项十分重要的工程措施,合理的施工导流方案对于加快施工进度、保证施工安全、降低工程投资有着重要的意义。施工导流过程中流场复杂,几乎每个大型工程制定施工导流规划时,都需采用模型试验以获得影响导流施工的水力学指标。施工导流工程水力学模型试验较为真实可信,但仍然存在一些问题,如试验结果会受到仪器测量精度影响,难以准确获得细部数据,消耗较多的人力和物力,试验周期较长等。相比物理模型试验,数值模拟可以弥补以上缺点。本文综合应用不同数学模型方法进行数值模拟,研究导流工程中不同流量下的整体流场及局部流场的水流变化。利用CATIA软件建立河道实际地形和建筑物三维几何模型,将几何模型导入FLOW-3D中,采用RNG k-ε紊流模型、卷气模型、漂移通量模型和Tru VOF水流自由表面追踪方法,计算了考虑溢洪道水流局部掺气条件下的导流工程整体流场,得到了流态、水位、流速、紊动能、压强、水流掺气浓度等水力参数的分布规律,并与物理模型试验成果进行了对比分析,结果表明数值模拟得到了较好的计算结果。计算得到了围堰堰前流速和堰前水位,得知堰脚不需要防护,上游围堰设计高程合理。为研究不同数学模型模拟局部导流流场水流掺气的情况,通过ICEM对整体导流模型修改得到溢洪道三维几何模型,运用六面体核心网格技术完成网格划分及网格质量优化,基于VOF模型和欧拉双流体模型,分别对溢洪道内掺气水流进行了模拟,得到了局部计算区域流场的水力参数,其中流速、紊动能、压强分布两种模型的计算结果基本一致。通过对比卷气模型、VOF模型、欧拉双流体模型模拟掺气水流的结果,可以确定初始掺气点可能的位置及掺气浓度分布规律,可以更好的为消除空蚀破坏提供参考。更多还原

【Abstract】 Construction diversion is a very important engineering measure that is unique throughout the construction of hydropower projects.Reasonable construction diversion schemes are of great significance for speeding up construction progress,ensuring construction safety and reducing engineering investment.The flow field is complex in the construction diversion process.When drawing up the construction diversion plan for almost every large-scale project,it is necessary to adopt model tests to obtain the hydraulic indicators affecting the diversion construction.The model test of construction diversion is more authentic,but there are still some problems such as the model test results will be affected by the accuracy of instrument measurement,it is difficult to obtain accurate detailed data,more manpower and material resources is consumed,and a long period is taken.Compared with physical model test,numerical simulation can make up for the above shortcomings.In the paper,model tests and different mathematical models are used to simulate the whole flow field and local flow field at different flow rates in diversion.The CATIA software is used to establish three-dimensional geometric model with complex terrain,and it is introduced into FLOW-3D.The RNG k-ε turbulence model,air entrainment model,drift-flux model and Tru VOF method tracing free surface are used to simulate the whole flow field of diversion engineering considering partial aeration in discharge flow of spillway.The flow regime,water level,velocity,turbulent kinetic energy,pressure on the bottom,aeration concentration in the spillway are obtained.Compared with the results of physical model test.the results show that the numerical simulation are better.The velocity and water level in front of the cofferdam are obtained by numerical simulation,and it was known that the foot of the cofferdam does not need to be protected and the design elevation of the upstream cofferdam is reasonable.In order to study the aeration with different mathematical models in the local diversion flow field,the three-dimensional geometric model of spillway is obtained by modifying the whole model through ICEM.The hexahedral core grid technology is used to complete the mesh generation and mesh quality optimization.The aerated flow in the spillway is simulated based on VOF model and Eulerian two-fluid model,and the hydraulic parameters of the local flow field are obtained.The results of velocity,pressure and turbulent kinetic energy are basically the same.The possible location of initial aeration point and the distribution law of aeration concentration can be obtained by comparing the simulation results of entrainment model,VOF model and Eulerian two-fluid model,which can provide better guidance for eliminating cavitation damage.更多还原