Numerical study of unstable wave trains in a hypersonic cone boundary layer and comparison with experiments

Abstract

Direct numerical simulations of three-dimensional artificially induced unstable wave trains propagating in a boundary layer over a 7◦ half-angle sharp cone at the freestream Mach number 5.92 are carried out. This numerical study simulates the experiments on boundary layer stability performed at ITAM SB RAS, Novosibirsk on a cone at zero angle of attack using artificial disturbances induced by a periodic electric glow discharge actuator. The actuator constitutes a point-like source on the wall and generates wave trains, that evolve downstream and excite first-mode instabilities. These experiments are simulated herein using numerical solution of Navier–Stokes equations with the in-house HSFlow solver implementing an implicit finite-volume shock-capturing method of second-order approximation. The computed disturbances spectra are compared with experimental data and a good agreement is demonstrated. In particular, the simulated azimuthal wavenumber distributions capture the subtle effect of nonlinear interactions between fundamental and sub-harmonic disturbances.