Turbulence Modeling of Shock Boundary Layer Interaction in Hypersonic Flows

Over the past few years, renewed interest in hypersonic research has significantly increased. Some of the most challenging obstacles in hypersonic vehicles design are associated with the shock wave turbulent boundary layer interactions (STBLI). This can cause a severe jump in pressure along with aerothermodynamic loads, which might result in structural damages or engine unstarts of hypersonic vehicles. Understanding the complex characteristics of these flows requires comprehensive physical experiments and detailed CFD turbulence modeling. In this dissertation, CFD simulations of STBLI using different turbulent modeling based on a set of experiments of hypersonic flow over a large hollow cylinder flare are examined. The turbulent models include Reynolds-Averaged Navier-Stokes (RANS) with 4 different closures ((k-, k-, Shear Stress Transport (SST), and Spalart-Allmaras (SA)) are evaluated in this study. These models are simulated with Mach numbers, which vary from 5-7 with ANSYS Fluent 19.2 in axisymmetric configurations. Also, the CFD analysis utilizing STARCCM+ (15.04) SA and Menter’s SST closures were used to obtain the heat transfer and pressure data associated with the STBLI in a two-dimensional model for Mach 6.0. In these cases, two sets of air properties were considered - one was based on ideal gas properties, and the other case used real gas equilibrium, and the effects of polyhedral and quadrilateral meshes in the simulation were examined. Then, SST and SA were evaluated for the same flowfield with Mach 6 in three-dimensional configurations. Lastly, Large Eddy Simulation (LES) with three different sub-grid scale techniques including the Smagorinsky-Lilly Model, Wall-Adapting Local Eddy-Viscosity (WALE), and Wall-Modeled LES (WMLES) were modeled. All the simulations results were compared with experimental data of a large hollow cylinder flare from CUBRC data. The three-dimensional RANS model showed significant improvement in both pressure and heat transfer prediction. While the LES model was computationally expensive, the model predictions for the STBLI were considerably improved compared to the two-dimensional simulations