Fox, J. S.O’Byrne, S.Houwing, A. F.P.Papinniemi, A.Danehy, P. M.Mudford, N. R.2025-12-312025-12-310001-1452ORCID:/0009-0007-2076-6766/work/162948442https://hdl.handle.net/1885/733797744Fluorescence imaging is used to investigate the separated flow upstream of a blunt fin in a hypersonic freestream with a transitional boundary layer. Images are presented to show the flow development before, during, and after the test time of the free-piston shock tunnel used to generate the flow. These images indicate that the test time in this facility is long enough to achieve a steady flow over the blunt fin. Thermocouple measurements are included to compare the surface heat flux upstream of the fin with that for flow along a flat plate with the same freestream conditions. The heat flux results are consistent with separation in a transitional boundary layer and show that the separated flow is oscillatory.9en200110.2514/2.14510035397719