中文摘要：

采用高精度直接数值模拟方法和高效的特征无反射边界条件,进行可压缩流转捩边界层中出现的次生流向涡演化的数值研究.精细的数值模拟结果清楚地揭示了转捩边界层的复杂流场中次生流向涡的形成和演化过程,探讨它对转捩至关重要的环状涡生成的影响,发现次生流向涡和主流向涡的共同作用形成环状涡的一种新机理.

英文摘要：

The formation and evolution of secondary streamwise vortices in the compressible transitional boundary layers over a flat-plate were studied by means of direct numerical simulation method with high order accuracy and high effective non-reflecting characteristic boundary conditions.The generation and development processes of the secondary streamwise vortices in the complicated transitional boundary flow are clearly analyzed based on the details of numerical results,and its effects on the formation of the ring-like vortex which is vital to the boundary layer transition are explored.A new mechanism forming the ring-like vortex through the mutual affection of the primary and secondary streamwise vortices is expressed.