叶栅尾迹涡系变迁数值模拟

【作者】 钟堰辉；

【导师】 张思青；

【作者基本信息】 昆明理工大学 ， 流体机械及工程， 2010， 硕士

【摘要】 混流式水轮机中水流绕流叶片或叶栅时产生水流分离,分离的尾迹形成较复杂的漩涡,通常产生于导叶后部、转轮流道及叶片的出口处。这些涡列会经历产生、向下游迁移的过程中变大至最后消亡的变化过程。导叶出口的尾迹涡系容易引起固定导叶、活动导叶及叶片的共振,甚至可能激发周围局部水流的共振,造成不同程度的破坏,同时,随着涡系的下移,会造成尾水管入口水流条件的恶化,进而加剧尾水管涡带的压力脉动,影响机组运行的稳定性和整机效率。因此有必要对叶栅尾迹涡系的变迁进行研究。本文以HLA351-LJ-170模型机的导水机构和转轮部分为对象建立了三维实体模型,用非结构化网格划分了计算域网格。采用Realizableκ-ε湍流模型和SIMPLEC算法进行了若干工况的三维定常计算,并设置滑移网格面,利用RNGκ-ε湍流模型和PISO算法进行了若干工况的导水机构、转轮一级动静干涉的三维非定常计算,通过定常计算和非定常计算得到了计算域内压强、速度分布及速度矢量图,以图形方式揭示了叶栅尾迹涡系的变化过程。更多还原

【Abstract】 When water flows through the Francis turbine’s blades or vane cascade,it will be separated, and forming many complex swirl. Vortex usually come from the rear of guide vanes, runner and the export part of runner blades. The vortex will go through a process of generation, migration to downstream and demise finally.Vortices exported from guide vane may easily lead the resonance of vanes, guide vanes and blades, and may even stimulate the resonance of local flow around, resulting in varying degrees of damage to water-turbine. At the same time, the vortex going down, will deteriorate flow conditions of entrance of the draft tube,and increase the pressure pulsation of draft tube,also affect the stability and efficiency of water-turbine. Therefore, it is necessary to research the changes of vortex exported from the vane cascade.In this paper, a three-dimensional solid model of the distributor and runner of HLA351-LJ-170 model water-turbine is established and computed field was meshed by nonstructural grid. Realizableκ-εturbulence model and SIMPLEC algorithm are used to do three-dimensional steady calculations under a number of conditions,after setting a moving mesh surface, RNGκ-εturbulence model and the PISO algorithm are used to do distributor-runner interaction three-dimensional unsteady calculations under a number of conditions. The distribution of static pressure, velocity in computed field and velocity vector diagram was obtained, the pictures reveal the change process of the vortices exported from the vane cascade.更多还原