Numerical Investigation of the Effect of the Sweep Angle of a Cylindrical Blunt Fin on the Shock Wave/Laminar Boundary Layer Interaction in a Hypersonic Flow

摘要

Hypersonic flights are mostly dominated by shock wave boundary layer interaction with potential critical effects on the performance of the vehicle. Gaining the ability to predict the flow in such regimes is very important for the design of high speed vehicles. The attempt of understanding the full fluid dynamics and mathematics of this complex interaction is still an ongoing research. The adverse pressure gradient imposed from the shock wave to the boundary layer can separate the boundary layer. The separation shock wave formed over the separated region can interact with the other shock waves and create a lambda shock wave structure with a transmitted shock wave. As the separated boundary layer reattaches to the surface, it increases the localized heat transfer and produces a reattachment shock wave, which increases the pressure on the surface of the vehicle. The assessment of the capability of a laminar perfect gas model to predict the heat transfer in a three-dimensional hypersonic flow with shock wave boundary layer interaction is one of the objectives of this study. A laminar hypersonic flow over a cylindrical blunt fin mounted on a flat plate is chosen to study and numerically simulate in this research. The freestream Mach number and Reynolds number - based on the diameter of the cylindrical fin - are 14 and 8,000, respectively. Numerical heat transfer on the blunt fin is compared with the experimental data for validation. Good agreement with the experimental results has been achieved, which validates the choice of the numerical model in this study. Moreover, investigation of the effects of the sweep angle of the blunt fin on the shock wave boundary layer interaction is the other objective of this research. Two discrete sweep angles of zero and 22.5 degree have been chosen and comparison of their results have been made. The unswept fin flowfield displays significant unsteadiness in the vicinity of the shock wave boundary layer interaction, while the 22.5~0 sweep angle case is virtually steady. The computed normalized peak heat transfer is approximately the same for both cases.