The University of Southampton
University of Southampton Institutional Repository

Numerical simulations of transition due to isolated roughness elements at Mach 6

Numerical simulations of transition due to isolated roughness elements at Mach 6
Numerical simulations of transition due to isolated roughness elements at Mach 6
An accurate prediction of transition onset behind an isolated roughness element has not yet been established. This is particularly important in hypersonic flow, where transition is accompanied by increased surface heating. In the present contribution, a number of direct numerical simulations have been performed of a Mach 6 boundary layer over a flat plate with isolated roughness elements. The effects of roughness shape, planform, ramps, and freestream disturbance levels on instability growth and transition onset are investigated. It is found that the frontal shape has a large effect on the transition onset, which is in agreement with previous studies, whereas the roughness element planform has a marginal influence. A new result is that the roughness shape in the streamwise direction (in particular, the aft section) is also an important characteristic, since an element with a ramped-down aft section allows the detached shear layer to spread out and weaken, leading to a lower instability growth rate. Above a critical value, the instability growth rate is found to be correlated with the amplitude of the low-speed streak formed by the roughness element, suggesting that a more physically based transition criterion should take account of the local liftup effect of the particular roughness shape.

0001-1452
1-13
Van den Eynde, Jeroen P. J. P.
a320edaf-9740-4316-bee4-7d7dda4457a4
Sandham, Neil D.
0024d8cd-c788-4811-a470-57934fbdcf97
Van den Eynde, Jeroen P. J. P.
a320edaf-9740-4316-bee4-7d7dda4457a4
Sandham, Neil D.
0024d8cd-c788-4811-a470-57934fbdcf97

Van den Eynde, Jeroen P. J. P. and Sandham, Neil D. (2015) Numerical simulations of transition due to isolated roughness elements at Mach 6. AIAA Journal, 1-13. (doi:10.2514/1.J054139).

Record type: Article

Abstract

An accurate prediction of transition onset behind an isolated roughness element has not yet been established. This is particularly important in hypersonic flow, where transition is accompanied by increased surface heating. In the present contribution, a number of direct numerical simulations have been performed of a Mach 6 boundary layer over a flat plate with isolated roughness elements. The effects of roughness shape, planform, ramps, and freestream disturbance levels on instability growth and transition onset are investigated. It is found that the frontal shape has a large effect on the transition onset, which is in agreement with previous studies, whereas the roughness element planform has a marginal influence. A new result is that the roughness shape in the streamwise direction (in particular, the aft section) is also an important characteristic, since an element with a ramped-down aft section allows the detached shear layer to spread out and weaken, leading to a lower instability growth rate. Above a critical value, the instability growth rate is found to be correlated with the amplitude of the low-speed streak formed by the roughness element, suggesting that a more physically based transition criterion should take account of the local liftup effect of the particular roughness shape.

Text
__soton.ac.uk_ude_PersonalFiles_Users_ra3n13_mydocuments_EPRINTS_VandenEyndeSandhamAIAAJ2015.pdf - Accepted Manuscript
Download (4MB)

More information

Accepted/In Press date: 24 April 2015
e-pub ahead of print date: 23 July 2015
Published date: 5 November 2015
Organisations: Aeronautics, Astronautics & Comp. Eng

Identifiers

Local EPrints ID: 384862
URI: http://eprints.soton.ac.uk/id/eprint/384862
ISSN: 0001-1452
PURE UUID: 0a04ac45-423e-43ca-9bc4-e91ec2ffbb5f
ORCID for Neil D. Sandham: ORCID iD orcid.org/0000-0002-5107-0944

Catalogue record

Date deposited: 11 Jan 2016 16:46
Last modified: 17 Dec 2019 01:54

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×