Study of Parameters Affecting Separation Bubble Size in High Speed Flows using k-ω Turbulence Model

Shock waves generated at different parts of vehicle interact with the boundary layer over the surface at high Mach flows. The adverse pressure gradient across strong shock wave causes the flow to separate and peak loads are generated at separation and reattachment points. The size of separation bubble in the shock boundary layer interaction flows depends on various parameters. Reynolds-averaged Navier-Stokes equations using the standard two-equation k-ω turbulence model is used in simulations for hypersonic flows over compression corner. Different deflection angles, including  ranging from 15o to 38o, are simulated at Mach 9.22 to study its effect on separated flow. This is followed by a variation in the Reynolds number based on the boundary layer thickness, Re from 1x105 to 4x105. Simulations at different constant wall conditions Tw of cool, adiabatic, and hot are also performed. Finally, the effect of free stream Mach numbers M∞, ranging from 5 to 9, on interaction region is studied. It is observed that an increase in parameters, , Re, and Tw results in an increase in the separation bubble length, Ls, and an increase in M∞ results in the decrease in Ls.

Keywords:

High speed flows , Shock/boundary-layer interaction , Hypersonic flows , Shock-waves , Boundary-layer , Compression corner , Computational fluid dynamics