Giuseppe Chiapparino, Christian Stemmer
DOI Number XXX-YYY-ZZZ
Conference Number HiSST-2022-373
Direct Numerical Simulations are performed to investigate roughness effects on a Mach 6 hypersonic
compression-corner flow. Different variants of a roughness patch placed upstream of the boundary-layer
smooth separation point are considered. The patches consist of sinusoidal elements, with modifications
in position and spanwise extension of the roughness. Compared to a smooth-wall case, all the rough
cases cause a delayed boundary-layer separation and hence a smaller recirculation bubble. Moreover,
the roughness-induced streamwise vorticity, which is convected downstream by the detached shear
layer, generates mushroom-like structures once the flow reattaches on the ramp. The properties of
such structures, although similar, reflect the character of the patch upstream of the bubble. The roughness inducing the locally largest flow distortion is responsible for the widest structure on the ramp,
characterized by the highest increase in wall-temperature peak. The patch occupying the entire width
of the domain generate instead the weakest vortices on the ramp.