Aerodynamic characteristics and the shock oscillation mechanism in a supersonic compressor cascade

The pursuit of higher blade loading in supersonic compressor rotor design has intensified research interest in shock wave/boundary layer interactions (SBLIs) within these systems. Interactions that induce large-scale separation and shock oscillations detrimentally impact compressor performance. This study investigates the influence of solidity and inflow angle on supersonic compressor cascade aerodynamics and the underlying shock oscillation mechanism in supersonic compressor cascade blades, employing schlieren visualization, Reynolds-averaged Navier-Stokes simulations, and large eddy simulations. Results demonstrate significant variations in shock system structure with differing solidity and inflow angle, leading to altered loss characteristics. These variations manifest as a forward shift of the impinging point where the pressure-side leading-edge shock reflects off the suction surface, increased reflections within the passage, and greater overall complexity of the passage shock system. Moreover, the shock oscillation mechanism is driven by the self-inhibited upstream development of the laminar portion within the separation bubble. Spatiotemporal distributions of isentropic Mach number reveal a distinct laminar region upstream and a diminishing laminar region downstream during propagation; upon reaching a critical length, instability within the shear layer suppresses the slender upstream region. When the shock and separation migrate downstream, a turbulent SBLI state emerges, triggering the onset of repetitive shock oscillations.