Effect of Wall Temperature on Hypersonic Double Ramp Flow Dynamics

Many hypersonic bodies employ wall cooling to maintain surface temperatures significantly below the recovery temperature. Wall temperature can greatly influence flow dynamics, including surface heat transfer, separation regions, and shock wave/boundary layer interactions (SWBLI). In this work, the effect of wall temperature on the flow dynamics over a 30^°-55^° double ramp geometry is investigated. Baseline simulations are conducted using the OpenFOAM solver rhoCentralFoam, and the results are validated against experimental data from Swantek & Austin (2012) for both laminar and turbulent regimes. Chemical effects are modeled using the JANAF thermochemical tables, while turbulence is accounted for using the k-ω SST model for SBLI simulations. Simulations are performed for both adiabatic and isothermal conditions with heated and cooled walls, with the wall to freestream temperature ratio ranging from s=T_w/T_∞=0.47 (cooled) to 1.57 (heated). The unsteady data reveal that the flow becomes increasingly unstable as the wall is cooled, and larger vortical structures are observed near the separation zone. Furthermore, the much thinner boundary layer delays the attachment of the oblique shock leg, elongating the separation region and shifting the triple point downstream. For the cooled wall case, the peak wall heat flux occurs slightly earlier, attains a value approximately 15% higher, and dissipates more rapidly.