ISBN: 978-1-56700-537-0
ISBN Online: 978-1-56700-538-7
ISSN Online: 2377-424X
International Heat Transfer Conference 17
NUMERICAL SIMULATION OF SUPERSONIC BOUNDARY LAYER RECEPTIVITY TO ENTROPY DISTURBANCES
Résumé
Direct numerical simulation and theoretical analysis of entropy receptivity are performed for the boundary layer on a sharp flat plate in Mach 6 flow at various angles of attack (AoA). Entropy wave passes through: the bow shock at AoA= 5°, the weak shock induced by the viscous-inviscid interaction at AoA=0°, or the expansion fan emanating from the plate leading edge at AoA=5°. The study is focused on cases where the integral amplification of unstable mode S (or Mack second mode) is sufficiently large (N≈8.4) to be
relevant to transition in low-disturbance environments. It is shown that excitation of dominant modes F and S occurs in a small vicinity of the sharp leading edge. The initial disturbance propagates further downstream in accord with the two-mode approximation model accounting for the mean-flow nonparallel effects and the intermodal exchange mechanism. This computationally economical model can be useful for predictions
of the second mode dominated transition onset using the physics-based amplitude method. Crosscomparisons of the initial amplitudes of excited modes help to evaluate the relative role of acoustic and entropy waves in the second-mode-dominated transition.