摘要
针对弯肘形尾水管内部流场广泛存在流动分离的特点,采用基于k-ω模型的SST(Shear Stress Transport)切应力输运模型进行湍流求解,克服了标准k-ε模型对逆压力梯度造成的流动分离预测精度低的缺点。同时为了避免结构化网格离散复杂形体需人工分区的缺点,采用了非结构混合网格方法。流场大部分区域为四面体网格,在边界附近采用加密的五面体棱柱型网格,满足了SST模型对边界层网格的要求;为了减少网格过粗引起的计算误差,还通过计算不同网格数下尾水管的压力恢复系数来优选出合适的网格数目。计算获得了分离流、二次流和多尺度旋涡结构,表明SST模型能很好地预测尾水管内的湍流流动。
In view of the broad existence of flow separation in the flow field of an elbow araft tube, SST （Shear Stress Transport） model based on κ-ω model is adopted to solve the turbulence, which overcomes κ-ω model＇s shortcoming of the low prediction precision of flow separation under adverse pressure gradients. In order to avoid the inconvenience of meshing separately in different area, the unstructured hybrid mesh method is adopted. As the tetrahedral grids exist in the majority area, the pentahedral prism grids are adopted near the boundary, which meets the SST model＇s requirement of mesh in the boundary layer. Pressure recovery factors under different number of grids are calculated so as to decrease the error from coarse mesh, then the suitable number of grids is obtained. Finally, separation flow, secondary flow and multi-scale eddy structure are simulated, it indicates that SST model can give a good prediction of turbulence in the draft tube.
出处
《水力发电学报》
EI
CSCD
北大核心
2006年第1期76-80,共5页
Journal of Hydroelectric Engineering
关键词
计算流体力学
流动预测
切应力输运模型
尾水管
流动分离
非结构混合网格
computational fluid dynamics
flow prediction
Shear Stress Transport （SST） model
draft tube
flow separation
unstructured hybrid mesh
