Development of new techniques for studying unsteady behavior in hypersonic boundary layer interactions

Shock dominated separated laminar hypersonic flows over a double cone geometry were investigated by analyzing unsteady direct simulation Monte Carlo signals with the residuals algorithm for unit Reynolds numbers gradually increasing from 9.35×10⁴ to 3.74×10⁵ m⁻¹ at a Mach number of 16. To investigate the origin of the striations in the bow shock observed in the amplitude functions of the highest Re number case, the momentum density was decoupled into thermal and acoustic parts using Doak’s momentum potential theory. The spatial distribution of the acoustic and thermal fields was found to be uniform for the lowest Reynolds number case whereas alternating patterns, especially in the vicinity of the separation zone and the triple point were observed for the acoustic field of the highest Reynolds number case. The thermal component of the momentum density was found to be large at the cone shoulder at later times due to a Kelvin-Helmholtz instability.