Numerical Investigation of Sweep Effect on Turbulent Shock-Wave Boundary-Layer Interaction

Abstract

Implicit large-eddy simulations of reflecting shock-wave turbulent boundary-layer interactions at a freestream Mach number of 2.05 were carried out for sweep angles of 0, 20, and 40 deg. The simulation for the unswept interaction reveals the shedding of spanwise coherent structures as well as a low-frequency unsteadiness at separation. Intermittent spanwise deformations of the separation line, also referred to as rippling, are observed with a frequency similar to that of the low-frequency unsteadiness. Interactions with 20 and 40 deg sweep are generated by adding a spanwise approach flow component. Because the inviscid shock system is not affected by the spanwise velocity component, the pressure rise across the impinging shock is the same as for the unswept interaction, and the resulting mean flowfields are similar. This approach, which enforces spanwise periodicity, can be understood as a model for interactions with perfect cylindrical similarity. For the swept interactions, the separated flow regions are enlarged, and the overall level of the pressure fluctuations is increased, although the relative increase of the pressure fluctuations over the interaction is reduced. For the swept cases, the low-frequency unsteadiness is shifted to higher frequencies, and the low-frequency amplitude is reduced compared to the unswept case. For 40 deg sweep, the rippling of the separation line is diminished, and oblique structures are observed downstream of the interaction.