中文摘要：

利用数值模拟的方法，研究了再人条件下，钝头体边界层中一种新的失稳机制．这种失稳机制无法用线性稳定性理论解释．最近的研究工作表明，流动中存在着一种与局部有限幅值扰动相关的失稳机制．它与常规的T-S波或二次失稳的过程不同．数值模拟了受空间模式的局部扰动影响的钝体头部超声速边界层的失稳过程．在模拟中，明确了不同扰动模型非线性相互作用的物理机制．

英文摘要：

A new instability mechanism in the boundary layer of blunt bodies was studied under reentry conditions by using numerical simulation method. The instability mechanism cannot be addressed by linear instability theory. The recent research shows that, there is a nonlinear instability mechanism associated with local finite amplitude disturbance, which differs from the ordinary instability with respect to the T-S wave and secondly instability. The instability process under the influence of the local disturbance in the boundary layer of blunt bodies was simulated numerically. The physical mechanisms for nonlinear interaction of various disturbance modes were identified in the simulation.