To study the self-excited oscillation in the isolator

the unsteady characteristics of the two dimensional planar inlet were numerically simulated using the finite volume method program with time and space terms of the two-order implicit and upwind discrete schemes

unstructured grid

and shear stress transport (SST) k -ω turbulence model when the high backpressure was applied

and the self-excited oscillation of the shock train was successfully captured. On this basis

proper orthogonal decomposition (POD) and dynamic modal decomposition (DMD) methods were utilized to analyze the oscillation. The results showed that the self-excited oscillation is a complex oscillation phenomenon dominated by a low frequency and coupled with multiple frequencies. Both the predictive models based on the POD and DMD methods can accurately and quickly predict the evolutions of flow field with the prediction error less than 0.2%. The time consuming of the former and the latter was 0.22 s and 0.05 s

respectively.