77th Annual Meeting of the APS Division of Fluid Dynamics (November 24, 2024 — November 26, 2024)
P2685195: Bow Shock Instability at Hypersonic Speed
DOI: https://doi.org/10.1103/APS.DFD.2024.GFM.P2685195
A novel instability in the bow shockwave during hypersonic planetary entry is presented. For the specific capsule geometry, density ratios above 13 across the bow shock and specific heat ratios below 1.2 generate an intense vorticity layer downstream of the discontinuity, leading to a Kelvin-Helmholtz instability. The unstable mode grows downstream in space and time and after a few milliseconds causes transition of all the flow behind the bow shock. This generates intense turbulent streaks that impinge on the capsule surface and cause a much higher heat load than in conventional laminar conditions. This phenomenon drastically changes the heat load requirements during the design of the heat shield and might be extremely relevant when exploring new planets. Numerical visualizations of the vorticity magnitude of the flow field around the capsule are shown. The spaceship is colored by the surface temperature. Results are obtained with a Wall-Modeled Large Eddy Simulation.
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