We study the transition of a Mach 5.65 laminar boundary layer tripped by an array of diamond shaped roughness elements using large-scale direct numerical simulations. A low Reynolds number experiment conducted at the Actively Controlled Expansion Hypersonic Wind Tunnel, Texas A & M University National Aerothermochemistry Laboratory is used to validate our simulation. Planar acoustic disturbances are applied at the in flow boundary to mimic the wind tunnel ambient environment. To accurately capture flow physics, a high- order, low-dissipation scheme for the convection terms in the Navier-Stokes equations is used. Visualizations and statistics of the flow explore the dominant and dynamically significant flow structures : the upstream vortex system, the shock system, and the downstream separated shear layer/wake region which originates from the top and sides of the roughness elements. Three-dimensional snapshots of pressure were considered to select dominant dynamic mode decomposition modes using Chu's disturbance energy norm. A coupled system at 30 kHz consisting of the shock system, the separated shear layer/wake region and the upstream vortex system is determined to have the most disturbance energy. The origin of disturbances is observed to be the upstream vortex system while the wake region acts as a dominant amplifier. Comparison of the flow structures and modes of transition between an isolated cylindrical roughness element and the array of diamond shaped roughness elements is performed.
|Original language||English (US)|
|Title of host publication||47th AIAA Fluid Dynamics Conference, 2017|
|Publisher||American Institute of Aeronautics and Astronautics Inc, AIAA|
|State||Published - 2017|
|Event||47th AIAA Fluid Dynamics Conference, 2017 - Denver, United States|
Duration: Jun 5 2017 → Jun 9 2017
|Name||47th AIAA Fluid Dynamics Conference, 2017|
|Other||47th AIAA Fluid Dynamics Conference, 2017|
|Period||6/5/17 → 6/9/17|
Bibliographical noteFunding Information:
The authors gratefully acknowledge the office of Naval Research through grant number N00014-15-1-2522 for the support of this research. The suggestions and findings obtained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the office of Naval Research. The authors thank Michael Semper and Rodney Bowersox for providing experimental data to validate the present study.
© 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.
Copyright 2017 Elsevier B.V., All rights reserved.