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采用时间模式对来流Mach数为4.5的平板边界层转捩过程做了直接数值模拟,然后对结果进行分析.发现在层流-湍流转捩的breakdown过程中,层流剖面得以快速转变为湍流剖面的机理在于扰动增长后,对平均剖面进行的修正导致了其稳定性特征的显著变化.虽然在层流下第二模态T-S波更不稳定,但在层流突变为湍流的过程中,第一模态不稳定波却占主导作用.
The time mode is used to directly simulate the plate boundary layer transition with a Mach number of 4.5 and the results are analyzed.The results show that during the breakdown of laminar-turbulent transition, the laminar flow profile can be rapidly transformed into turbulent flow The mechanism of the profile is that after the perturbation increases, the correction of the average profile leads to significant changes of its stability characteristics. Although the second mode TS wave is more unstable under laminar flow, in the process of the sudden change of laminar flow to turbulent flow, A mode unstable wave is dominant.