Numerical Simulation of Swirling Flow in Complex Hydroturbine Draft Tube Using Unsteady Statistical Turbulence Models
Numerical Simulation of Swirling Flow in Complex Hydroturbine Draft Tube Using Unsteady Statistical Turbulence Models
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DOI：
10.1061/(asce)0733-9429(2005)131:6(441
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发表时间：
2005-06
影响因子：
2.4
通讯作者：
J. Paik;F. Sotiropoulos;M. Salé
中科院分区：
文献类型：
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作者：
J. Paik;F. Sotiropoulos;M. Salé
发展了一种在复杂三维几何条件下进行非定常雷诺平均Navier-Stokes（URANS）模拟和分离涡模拟（DES）的数值方法。应用该方法对典型水轮机尾水管内的不可压旋流进行了数值模拟，尾水管由90°强弯曲弯管和两个墩柱组成。控制方程求解二阶精度，有限体积，双时间步进人工压缩性方法的雷诺数为110万与180万个节点的网格。尾水管的几何复杂性处理使用区域分解重叠（嵌合体）网格。数值模拟表明，非定常统计湍流模型可以捕捉由几何诱导的大尺度不稳定性和非定常拟序结构主导的非常复杂的三维流动现象，例如涡破裂的开始和涡轮机转轮下游非定常绳涡的形成。URANS和DES似乎都产生了与测量结果合理一致的平均速度剖面的一般形状和大小。在直下游扩压器中，也观察到DES和URANS预测的湍流统计数据之间存在显著差异。
A numerical method is developed for carrying out unsteady Reynolds-averaged Navier-Stokes (URANS) simulations and detached-eddy simulations (DESs) in complex 3D geometries. The method is applied to simulate incompressible swirling flow in a typical hydroturbine draft tube, which consists of a strongly curved 90° elbow and two piers. The governing equations are solved with a second-order-accurate, finite-volume, dual-time-stepping artificial compressibility approach for a Reynolds number of 1.1 million on a mesh with 1.8 million nodes. The geometrical complexities of the draft tube are handled using domain decomposition with overset (chimera) grids. Numerical simulations show that unsteady statistical turbulence models can capture very complex 3D flow phenomena dominated by geometry-induced, large-scale instabilities and unsteady coherent structures such as the onset of vortex breakdown and the formation of the unsteady rope vortex downstream of the turbine runner. Both URANS and DES appear to yield the general shape and magnitude of mean velocity profiles in reasonable agreement with measurements. Significant discrepancies among the DES and URANS predictions of the turbulence statistics are also observed in the straight downstream diffuser.