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Pressure gradient effects on wake-flow instabilities behind isolated roughness elements on re-entry capsules

Theiß, Alexander and Leyh, Sascha and Hein, Stefan (2019) Pressure gradient effects on wake-flow instabilities behind isolated roughness elements on re-entry capsules. Proceedings of the Institution of Mechanical Engineers Part G-Journal of Aerospace Engineering. SAGE Publications. DOI: 10.1177/0954410019844067 ISSN 0954-4100

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Official URL: https://doi.org/10.1177%2F0954410019844067

Abstract

Laminar-turbulent transition caused by modal disturbance growth in the wake flow of isolated roughness elements on blunt re-entry capsules is studied numerically at typical cold hypersonic wind-tunnel conditions. Two fundamentally different heat shield shapes are considered. On the sphere-cone forebody the wake flow of the roughness is exposed to an adverse pressure gradient, whereas the spherical heat shield exhibits a strongly favorable pressure gradient. The pressure gradient effects on the development of the stationary wake flow and its modal instability characteristics are discussed for various heights and diameters of the cylindrical roughness element. Regions of increased shear develop in its wake, which persist longer in the adverse pressure gradient case. Consequently, the results of spatial two-dimensional eigenvalue analyses reveal that the unstable wake-flow region extends much further downstream and the wake-mode instabilities are considerably more amplified. The disturbance kinetic energy production terms are used to assess the contributions of the different shear-layer regions to the mode growth and its dependence on the pressure gradient.

Item URL in elib:https://elib.dlr.de/129347/
Document Type:Article
Title:Pressure gradient effects on wake-flow instabilities behind isolated roughness elements on re-entry capsules
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Theiß, AlexanderAlexander.Theiss (at) dlr.dehttps://orcid.org/0000-0003-4034-3246
Leyh, SaschaUNSPECIFIEDUNSPECIFIED
Hein, StefanStefan.Hein (at) dlr.deUNSPECIFIED
Date:16 May 2019
Journal or Publication Title:Proceedings of the Institution of Mechanical Engineers Part G-Journal of Aerospace Engineering
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
DOI :10.1177/0954410019844067
Editors:
EditorsEmail
UNSPECIFIEDSAGE Publications Ltd
Publisher:SAGE Publications
ISSN:0954-4100
Status:Published
Keywords:Laminar-to-turbulent transition, blunt body, roughness-induced transition, re-entry capsule, linear stability theory, LST-2D
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Flight Physics
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > High Speed Configurations, GO
Deposited By: Theiß, Alexander
Deposited On:01 Oct 2019 14:53
Last Modified:01 Oct 2019 14:53

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