Wall-Modeled Large-Eddy Simulation of Hypersonic Boundary Layer Transition over a Cone-Cylinder-Flare

Wall-modeled large-eddy simulations (WMLES) of hypersonic boundary layer transition over a cone-cylinder-flare geometry are performed. The compressible Navier-Stokes equations for an ideal gas are solved numerically using the MEG-C scheme for spatial discretization of the convective terms and an alpha-damping method for the viscous terms. To model inner-layer dynamics, we employ the Compressible Equilibrium ODE Wall-Stress Model. We consider Mach 6 transitional flow over a 5 mm nose-tip radius cone-cylinder-flare geometry with 5-deg half-angle cone and 12-deg flare. As validation, Mach 7.7 transition to turbulence over a 15-deg compression ramp is simulated. Good agreement with both DNS and experiment is achieved for time- and spanwise-averaged wall pressure coefficient. The predicted Stanton number shows good agreement within the separation bubble, despite strong non-equilibrium effects. Separation and reattachment locations are shifted slightly upstream of the reference data. While reattachment is accurately captured, heat flux downstream is over-predicted. A modification to the wall model is proposed to address this. In the cone-cylinder-flare case, the WMLES accurately predicts the surface heat flux distribution, resolves dominant POD fluctuation frequencies at 20 kHz, 45 kHz, and 60 kHz, and captures rope- and wisp-like wave structures observed experimentally.