Direct Numerical Simulation of Microramp-Controlled Shock–Boundary-Layer Interactions: Effects of Ramp Size and Location

Shock–boundary-layer interactions (SBLIs) occur in most high-speed aerospace applications, often causing flow separation, pressure and heat peaks, increased drag, and unsteadiness. Microvortex generators offer an interesting passive control strategy by improving flow characteristics without excessive parasitic drag. This study uses direct numerical simulation (DNS) to investigate the impact of microramp arrays on a supersonic SBLI generated by an oblique shock impinging on a turbulent boundary layer at Mach 2.28 and friction Reynolds number 550. Four configurations are examined: one baseline uncontrolled and three controlled cases with variations in microramp size and placement relative to the interaction zone. Results indicate that microramps modulate the separation bubble spanwise, forming a saddle-shaped structure. Larger microramps enhance wake lift-up and momentum transfer toward the near-wall region, delaying separation and promoting earlier reattachment, but at the cost of increased device drag. Position changes have minor influence, primarily near the symmetry plane, suggesting that control effectiveness is relatively insensitive to shock distance. Although limited to a small set of geometrical parameters, these high-fidelity data provide valuable insight into the parametric behavior of microramp-controlled SBLIs.