Analysis of Reattachment Streaks in Hypersonic Shockwave-Boundary Layer Interactions with Upstream Roughness

Abstract A blunt-nosed ogive-cylinder-flare model was tested in Mach 6 flow at Texas A&M University’s ACE blowdown tunnel with swept Reynolds number and angle-of-attack (AoA). IR thermography and schlieren imaging on the windward side were taken concurrently to determine surface heating distribution and flow structure around the shear layer reattachment onto the flare. The resulting schlieren imaging data showed flow structure having a predominately linear dependence on Re/x for 0◦ AoA and 2◦ AoA and being independent of Re/x for 4◦ AoAand 6◦ AoA. The spanwise periodicity of surface heating streaks associated with surface vortices ranged between 10◦ and 30◦. Bifurcation of the spanwise streaks was observed for nonzero AoA and the coalescing of the bifurcated streaks was observed downstream. At 0◦ and 2◦ AoA, the length and movement of the span-wise streaks are more strongly affected by the changing freestream Re/x than at 4◦ AoA and 6◦ AoA. Additionally, spanwise peak-to-trough surface streak St values varied significantly, with maximum ∆St of 3.3 × 10-3, 6.9 × 10-3,8.7×10-3, and 8.2×10-3 for the 0◦ through 6◦ AoA case respectively, neglecting tunnel startup. Convergence of peak St values is seen beyond Re/x = 5 × 106m-1. A novel correlation is proposed relating freestream and flow conditions with surface heating distribution.