基于转捩SST模型凸起圆柱绕流数值研究

为了研究局部凸起对边界层转捩的影响，采用转捩SST模型分别对亚临界、临界和超临界状态下带突起的圆柱绕流问题进行了数值模拟，分析了不同Reynolds数下带突起的圆柱绕流问题的近壁面流动特征以及表面时均压力与摩擦力系数的分布和凸起对圆柱表面流动分离以及转捩的影响，对比了有无凸起两侧圆柱表面时均压力、摩擦力系数的不同. 结果表明:当来流Reynolds数处于临界区时，气流在圆柱上表面凸起处形成了3个反向旋转的漩涡，之后随着θ的增大，发生了流动分离和流动转捩现象；对于不同Reynolds数下的来流，圆柱上表面的凸起可以使气流发生转捩的位置提前；圆柱上表面的凸起使流速增大、压强降低，从而导致圆柱产生升力，随着来流Reynolds数的增大，其升力逐渐变大. 

Numerical Study of Flow Around a Raised Cylinder Based on Transition SST Model

In order to study the influence of local bulge on boundary layer transition,the transition SST model was used to simulate the flow around the convex cylinder at high Reynolds numbers.The flow around convex cylinder in subcritical,critical and supercritical conditions was simulated respectively.The flow characteristics of the cylinder with bulge at different Reynolds numbers and the distribution of the mean pressure and friction coefficient were analyzed.The influence of bulge on the flow separation and transition of cylinder surface was analyzed.The differences of pressure and friction coefficient between two sides of cylinder with and without bulge were compared.The results show that when the Reynolds number of the incoming flow is in the critical region,three counter rotating vortices are formed on the convex surface of the cylinder,and then with the increase ofθ,flow separation and flow transition occur.For different Reynolds numbers,the convexity on the surface of cylinder can advance the transition position.With the increase of Reynolds number,the lift force increases gradually.