关键词: 转捩模式;流场;激波;涡;边界层;转捩

Abstract: The hypersonic boundary layer transition induced by roughness element in BAM6QT is simulated using γ-Re_θ transition model based on IDDES method. The root-mean-square of wall pressure fluctuations, the dominant frequency of the disturbance and the mean Pitot pressure distribution in the wake boundary layer are compared with the experiment results quantitatively. The flow field structures are compared with DNS results qualitatively. The results show that this new method has the ability to simulate the formation, development and break down process of the roughness element induced stream wise vortex and to capture the vibration between the separation shock and the bow shock in the upstream of the roughness element. The simulating results also show that the stream wise vortex structures begin to break down at around 40 times of the element diameter downstream. The unsteady disturbance energy achieves the maximum value around this point too. Obvious streak vortices are induced by the roughness elements. Among them, the low speed streaks are in the upper region of the boundary layer. They gradually move to the outside of the boundary layer and dissipate at last. While the high speed streaks, in the bottom region of the boundary layer, spread to both sizes while developing downstream. The contact and interaction of several high speed streaks leads the finally break down of the vortex structures and the transition of the boundary layer in the wake region.

Key words: Transition model;Flow field;Shock wave;Vortex;Boundary layer;Transition