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Transition Delay by Oblique Roughness Elements in a Blasius Boundary-Layer Flow

Lemarechal, Jonathan and Klein, Christian and Henne, Ulrich and Puckert, Dominik K. and Rist, Ulrich (2018) Transition Delay by Oblique Roughness Elements in a Blasius Boundary-Layer Flow. In: AIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting, 210059 (1057), pp. 1-17. AIAA. AIAA SciTech 2018, 08.01.2018-12.01.2018, Kissimmee, Florida, USA. DOI: 10.2514/6.2018-1057 ISBN 978-162410524-1

Full text not available from this repository.

Official URL: https://arc.aiaa.org/doi/10.2514/6.2018-1057

Abstract

A passive device to delay the laminar-turbulent transition in a Blasius boundary-layer flow is tested at low Reynolds numbers in the laminar water channel of the Institute of Aerodynamics and Gas Dynamics (University of Stuttgart). The passive device consists of oblique surface roughness elements lined up perpendicular to the flow. Each element has the shape of a cuboid, is oriented 45° to the direction of the oncoming flow, and generates a nonsymmetric vortex system. From this vortex system only one vortex per roughness element persists and a co-rotating vortex structure remains after 50 roughness heights downstream of the elements. These vortices generate high and low speed streaks inside of the boundary layer through the lift-up effect. The streaks alter the two-dimensional (2D) boundary layer into a three-dimensional (3D) one. For correctly placed and sized roughness elements the 2D Tollmien-Schlichting wave is altered into a 3D less amplified wave and the transition occurs further downstream. The flow is investigated by means of surface visualizations with the Temperature-Sensitive Paint (TSP) method and velocity measurements with hot-film anemometry. With the TSP method the laminar-turbulent transition was measured with high spatial and temporal resolution. The changes of transition location and changes of transition mechanism are well captured.

Item URL in elib:https://elib.dlr.de/120936/
Document Type:Conference or Workshop Item (Speech)
Additional Information:AIAA 2018-1057
Title:Transition Delay by Oblique Roughness Elements in a Blasius Boundary-Layer Flow
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Lemarechal, JonathanJonathan.Lemarechal (at) dlr.deUNSPECIFIED
Klein, Christianchristian.klein (at) dlr.deUNSPECIFIED
Henne, Ulrichulrich.henne (at) dlr.deUNSPECIFIED
Puckert, Dominik K.Institut für Aerodynamik und Gasdynamik, Universität StuttgartUNSPECIFIED
Rist, UlrichInstitut für Aerodynamik und Gasdynamik, Universität StuttgartUNSPECIFIED
Date:8 January 2018
Journal or Publication Title:AIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:No
Volume:210059
DOI :10.2514/6.2018-1057
Page Range:pp. 1-17
Publisher:AIAA
Series Name:Conference Proceedings online
ISBN:978-162410524-1
Status:Published
Keywords:Laminar-Turbulent Transition, Blasius Boundary Layer, K-Type Transition, Passive Transition Delay, Streaks, Temperature-Sensitive Paint, TSP, Hot-Film Anemometry, Laminar Water Channel, Laminarwasserkanal, Low Reynolds Number Experiment
Event Title:AIAA SciTech 2018
Event Location:Kissimmee, Florida, USA
Event Type:international Conference
Event Dates:08.01.2018-12.01.2018
Organizer:AIAA
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 - Simulation and Validation
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Experimental Methods, GO
Deposited By: Micknaus, Ilka
Deposited On:13 Jul 2018 08:35
Last Modified:09 Jan 2019 08:49

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