基于Transition SST模型的高雷诺数圆柱绕流数值研究

为了研究高雷诺数下圆柱绕流边界层的转捩现象和圆柱尾迹近壁区的流动特征,首先通过在典型雷诺数下采用Transition SST四方程转捩模型模拟圆柱绕流得到的结果与实验结果及采用SST k-ω两方程湍流模型模拟结果的对比分析,验证了Transition SST模型在模拟高雷诺数下圆柱绕流的优越性,并较为准确地预测出了圆柱绕流边界层的转捩现象及尾迹近壁区的流动特征。然后分别对亚临界区、临界区、超临界区和过临界区的圆柱绕流问题进行了数值模拟,分析了不同雷诺数下圆柱绕流的流场结构及圆柱表面压力系数、摩擦力系数的变化规律,研究了圆柱绕流近壁区的流动特征、边界层转捩的流动机理、转捩位置及其随雷诺数的变化规律。结果表明,亚临界区二维圆柱绕流边界层发生层流分离,无分离泡和转捩现象;临界区和超临界区二维圆柱绕流边界层先产生了分离泡现象,之后流动发生了转捩并在转捩后发生湍流分离;过临界区二维圆柱绕流边界层流动在转捩之后发生湍流分离,无分离泡现象;在临界区、超临界区和过临界区,二维圆柱绕流边界层转捩位置随雷诺数增大向前驻点移动。

Numerical simulation for flow around circular cylinder at high Reynolds number based on Transition SST model

In order to study the boundary layer transition phenomenon and the flow characteristics of flow around circular cylinder at high Reynolds number, the experimental results and the results that are obtained by using the Transition SST model and the SST k-ω model were firstly analyzed at typical Reynolds number, and the advantages of the Transition SST model was verified at high Reynolds number. Meanwhile, the boundary layer transition phenomenon and the flow characteristics were more accurately predicted. Then, the numerical simulations were performed in subcritical, critical, supercritical and over critical regions. The variation of flow field structure and the friction coefficient curve was analyzed under the different Reynolds number. The flow characteristics, flow mechanism of boundary layer transition, and variation of transition positions were studied. Results show that the boundary layer separates laminarly, and the flow does not form a separation bubble and transition phenomenon in subcritical region; in critical and supercritical region, the flow forms a separation bubble, and ultimately turbulent separation happens after transition occurs with the flow; in over critical region, the boundary layer separates turbulently after transition occurs with the flow, and the flow does not form a separation bubble; the more the Reynolds number is, the closer the transition position is to the front stagnation point of cylinder in critical, supercritical and over critical region.