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Turbulence structures and statistics of a supersonic turbulent boundary layer subjected to concave surface curvature

Turbulence structures and statistics of a supersonic turbulent boundary layer subjected to concave surface curvature
Turbulence structures and statistics of a supersonic turbulent boundary layer subjected to concave surface curvature

Supersonic turbulent flows at Mach 2.7 over concave surfaces for two different radii of curvature were investigated and compared with a flat plate turbulent boundary layer using direct numerical simulations. The streamwise velocity reduces in the outer part of the boundary layer due to compression, while it increases near the wall due to curvature, with a higher shape factor for the concave cases. The near-wall spanwise streak spacing reduces compared to the flat plate, with large-scale streaks and turbulence amplification also observed. Streamwise velocity iso-surfaces and streamlines show the generation of Görtler-like vortices, consistent with significant centrifugal effects. Abundant small vortices are shown to be associated with large baroclinic production of vorticity that is caused by the density and pressure gradients that are associated with concave compression. Profiles of turbulent kinetic energy and turbulent Mach number exhibit a characteristic two-layer structure in the concave boundary layer cases. In the outer layer, turbulence is greatly amplified, whereas a local balance exists in the inner layer. Turbulent energy budget analysis shows that both production and dissipation increase near the concave wall, whereas in the outer part of the boundary layer, the production is increased and ultimately balanced by convection and turbulent transport.

boundary layer structure, compressible boundary layers, high-speed flow
0022-1120
60-99
Sun, Mingbo
2df9eb75-e5d8-48cf-b8e1-00b0b77b3a90
Sandham, Neil D.
0024d8cd-c788-4811-a470-57934fbdcf97
Hu, Zhiwei
dd985844-1e6b-44ba-9e1d-fa57c6c88d65
Sun, Mingbo
2df9eb75-e5d8-48cf-b8e1-00b0b77b3a90
Sandham, Neil D.
0024d8cd-c788-4811-a470-57934fbdcf97
Hu, Zhiwei
dd985844-1e6b-44ba-9e1d-fa57c6c88d65

Sun, Mingbo, Sandham, Neil D. and Hu, Zhiwei (2019) Turbulence structures and statistics of a supersonic turbulent boundary layer subjected to concave surface curvature. Journal of Fluid Mechanics, 865, 60-99. (doi:10.1017/jfm.2019.19).

Record type: Article

Abstract

Supersonic turbulent flows at Mach 2.7 over concave surfaces for two different radii of curvature were investigated and compared with a flat plate turbulent boundary layer using direct numerical simulations. The streamwise velocity reduces in the outer part of the boundary layer due to compression, while it increases near the wall due to curvature, with a higher shape factor for the concave cases. The near-wall spanwise streak spacing reduces compared to the flat plate, with large-scale streaks and turbulence amplification also observed. Streamwise velocity iso-surfaces and streamlines show the generation of Görtler-like vortices, consistent with significant centrifugal effects. Abundant small vortices are shown to be associated with large baroclinic production of vorticity that is caused by the density and pressure gradients that are associated with concave compression. Profiles of turbulent kinetic energy and turbulent Mach number exhibit a characteristic two-layer structure in the concave boundary layer cases. In the outer layer, turbulence is greatly amplified, whereas a local balance exists in the inner layer. Turbulent energy budget analysis shows that both production and dissipation increase near the concave wall, whereas in the outer part of the boundary layer, the production is increased and ultimately balanced by convection and turbulent transport.

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ConcaveJFM final submission - Accepted Manuscript
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Accepted/In Press date: 24 December 2018
e-pub ahead of print date: 18 February 2019
Published date: 25 April 2019
Keywords: boundary layer structure, compressible boundary layers, high-speed flow

Identifiers

Local EPrints ID: 429641
URI: https://eprints.soton.ac.uk/id/eprint/429641
ISSN: 0022-1120
PURE UUID: c105c2f1-c316-4dc4-b208-441e7b7a2236
ORCID for Neil D. Sandham: ORCID iD orcid.org/0000-0002-5107-0944

Catalogue record

Date deposited: 02 Apr 2019 16:30
Last modified: 20 Aug 2019 04:01

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Contributors

Author: Mingbo Sun
Author: Neil D. Sandham ORCID iD
Author: Zhiwei Hu

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