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Flow Reversal in Turbulent Boundary Layers with Varying Pressure Gradients

Willert, Christian and Cuvier, Christophe and Soria, Julio and Foucaut, Jean Marc and Laval, Jean Philippe (2018) Flow Reversal in Turbulent Boundary Layers with Varying Pressure Gradients. In: Proceedings of the 5th International Conference on Experimental Fluid Mechanics, pp. 396-401. Universität der Bundeswehr, München. 5th International Conference on Experimental Fluid Mechanics ICEFM 2018, 02.-04. Jul. 2018, München, Deutschland. DOI: 10.18726/2018_2 ISBN 978-3-943207-32-3

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Official URL: https://athene-forschung.unibw.de/124262?show_id=124123

Abstract

This contribution describes detailed PIV measurements obtained in turbulent boundary layers in order to capture rarely occurring flow reversals within the viscous sublayer, which previously have been observed in both experiments and direct numerical simulations. Due to their confinement to the viscous sublayer along with their rare occurrence on the order of 10^-4, any statistical investigation requires very large data sets exceeding 10^5 samples. In the present investigation, this was achieved by capturing long PIV records using image high magnification near unity. To investigate the influence of Reynolds number and pressure gradient, the measurements were performed in turbulent boundary layers in both zero pressure Gradient (ZPG) and adverse pressure gradient (APG) conditions. The measurements were conducted in the TBL wind tunnel of Lille which features a test section length of 20 m and cross-section of 2x1 m^2. A ramp model placed inside the tunnel introduced APG conditions. Both visual inspection of the raw data and a dedicated processing scheme to retrieve the unsteady wall shear stress were used to quantify the flow reversal events. The occurrence of the self-similar flow reversals was found to weakly depend on the Reynolds numbers in ZPG and roughly doubled in frequency in the APG condition.

Item URL in elib:https://elib.dlr.de/121150/
Document Type:Conference or Workshop Item (Speech)
Title:Flow Reversal in Turbulent Boundary Layers with Varying Pressure Gradients
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Willert, ChristianChris.Willert (at) dlr.dehttps://orcid.org/0000-0002-1668-0181
Cuvier, ChristopheLMFL FRE3723, Centrale Lille, CNRS, Villeneuve d'Ascq, FranceUNSPECIFIED
Soria, JulioMonash University, VIC 3800, AustraliaUNSPECIFIED
Foucaut, Jean MarcLMFL FRE3723, Centrale Lille, CNRS, Villeneuve d'Ascq, FranceUNSPECIFIED
Laval, Jean PhilippeLMFL FRE3723, Centrale Lille, CNRS, Villeneuve d'Ascq, FranceUNSPECIFIED
Date:2 July 2018
Journal or Publication Title:Proceedings of the 5th International Conference on Experimental Fluid Mechanics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
DOI :10.18726/2018_2
Page Range:pp. 396-401
Editors:
EditorsEmail
Kähler, Christian J.Uni BW München
Hain, RainerUni BW München
Scharnowski, SvenUni BW München
Fuchs, ThomasUni BW München
Publisher:Universität der Bundeswehr, München
ISBN:978-3-943207-32-3
Status:Published
Keywords:turbulent boundary layer, wall shear stress, adverse pressure gradient, particle image velocimetry, PIV, particle tracking velocimetry, PTV, long-range micro PIV, turbulence, flow visualization, image-based velocimetry
Event Title:5th International Conference on Experimental Fluid Mechanics ICEFM 2018
Event Location:München, Deutschland
Event Type:international Conference
Event Dates:02.-04. Jul. 2018
Organizer:Universität der Bundeswehr, München
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:propulsion systems
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Virtual Engine and Validation methods
Location: Köln-Porz
Institutes and Institutions:Institute of Propulsion Technology > Engine Measurement Systems
Deposited By: Willert, Dr.phil. Christian
Deposited On:30 Jul 2018 09:31
Last Modified:31 Jul 2019 20:18

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