Loss of axial symmetry in hypersonic flows over conical shapes

Axial symmetry is a common assumption in hypersonic flows over conical geometries, yet many exhibit unsteady, three-dimensional instabilities. Using triple-deck theory, linear stability analysis, and direct simulation Monte Carlo, we examine non-axisymmetric azimuthal eigenmodes in Mach 16 flows. The strongest amplification occurs for azimuthal wavenumber n=1 near the cone tip due to interactions between the conical shock and the viscous shear layer. In double-cone flows, these three-dimensional effects alter the surface properties where the transmitted conical shock hits the wall, challenging axial symmetry assumptions and laminar-to-turbulent transition.