The growth rate of inflectional instability and viscous instability also saturate similarly to the primary and nonlinearly generated disturbances . the main effect of inflectional instability mode in the final breakdown seems to interact with the disturbances having developed and thus widens the frequency spectrum to turbulent state 属于拐点不稳定性的高频二次不稳定模态对最后转捩的影响主要体现在与其它扰动的相互作用,并导致出现紊流状态宽带频谱。