The unsteadiness of shock wave-boundary layer interactions is investigated in a transitional backward-facing step flow at Ma=1:7 and Red0 =13718 using large eddy simulation. The mean and instantaneous flow shows that the laminar inflow undergoes a laminar-to-turbulence transition in which Kelvin-Helmholtz vortices form, distort and eventually break down into small hairpin-like vortices. The interaction system features broadband frequency oscillations in a range f d0=u¥ = 0:03 _ 0:23 based on the spectral and statistical analysis. The results of dynamic mode decomposition indicate that the medium-frequency motions centered at f d0=u¥ = 0:06 are related to the shock winkling and the shedding of large coherent vortices, while the lower (centered at f d0=u¥ _ 0:01) and higher ( f d0=u¥ _ 0:1) frequency unsteadiness is associated with the periodical dilatation and shrinking of separation system and the convection of upstream K-H vortices respectively.
|Title of host publication||54th 3AF International Conference AERO2019 At: Paris, France|
|Number of pages||10|
|Publication status||Published - 2019|
|Event||54th 3AF International Conference on Applied Aerodynamics - Paris, France|
Duration: 25 Mar 2019 → 27 Mar 2019
Conference number: 54
|Conference||54th 3AF International Conference on Applied Aerodynamics|
|Abbreviated title||AERO 2019|
|Period||25/03/19 → 27/03/19|
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