Passive Control of Shock Wave Turbulent Boundary Layer Interaction over a Perforated Wall

Abstract

Wall-resolved large-eddy simulations are performed to study the interaction between a supersonic turbulent boundary layer and an impinging shock over a wall. The freestream conditions used were Mach 2 and a moderate friction Reynolds number of 𝑅𝑒𝜏 = 950. A passive control method was implemented using perforations in the interaction region of influence of the reference case (flat plate), with the addition of two separated cavities beneath the perforations. The cavities were designed to work as Helmholtz-like resonators at a separation length-based Strouhal number of 𝑆𝑡_𝐿𝑠𝑒𝑝 ≈ 0.03. For the reference case results consistent with the literature were obtained and a time analysis, based on the cross-correlations between dynamic properties allowed to suggest a sequence of events driving the unsteadiness of the interaction. The controlled case, resulted in a larger region of influence of the interaction, with the blowing-suction mechanism inside the cavities allowing a reduction of the separation length. Large oscillations were found close to the wall for thermodynamic properties, but also skin friction and wall-normal velocity. The topology of the recirculation bubble changed to become less symmetric resulting in a stronger reattachment compression fan. Regarding the unsteadiness of the controlled interaction, a tonal behaviour was found (at 𝑆𝑡_𝐿𝑠𝑒𝑝 ≈ 0.3) for the reflected shock motion associated with the resonant frequency found inside the cavities and also for the bubble volume variation. In general, the resonance within the cavities seemed to be able to affect the dynamics of the interaction, despite maintaining its global topology.