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Experimental study of bump effects on boundary-layer transition in compressible high Reynolds number flow

Costantini, Marco and Risius, Steffen and Koch, Stefan and Fuchs, Carsten and Gerhard, Uwe and Hein, Stefan and Klein, Christian (2019) Experimental study of bump effects on boundary-layer transition in compressible high Reynolds number flow. Experimental Thermal and Fluid Science, 106 (09), pp. 234-254. Elsevier. DOI: 10.1016/j.expthermflusci.2019.04.027 ISSN 0894-1777

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Official URL: https://doi.org/10.1016/j.expthermflusci.2019.04.027

Abstract

The influence of surface bumps on boundary-layer transition was experimentally investigated in the present work. The experiments were conducted in a (quasi-) two-dimensional flow at low to high subsonic Mach numbers and chord Reynolds numbers up to 10 million in the low-turbulence Cryogenic Ludwieg-Tube Göttingen. Various streamwise pressure gradients relevant for natural laminar flow surfaces were implemented. Quasi-two-dimensional bumps, with a sinusoidal shape in the streamwise direction (positive half of a sine), fixed length and three different heights, were installed on a two-dimensional flat-plate model. The model was equipped with temperature-sensitive paint for non-intrusive transition detection and with pressure taps for the measurement of the surface pressure distributions. Boundary-layer transition was shown to occur at a more upstream location with increasing bump height-to-length ratio. This was mainly due to the local adverse pressure gradient on the downstream side of the bump, which was particularly pronounced in the case of the bump with the largest height-to-length ratio, thereby inducing boundary-layer separation (as verified via oil-film visualizations). In the case of the bump with the smallest height-to-length ratio, bump-induced transition was found to be dependent on global pressure gradient, Mach number and Reynolds number; however, the influence of these parameters on transition induced by bumps with larger height-to-length ratios was significantly reduced. The sensitivity of boundary-layer transition to the effect of the bumps was shown to be more pronounced with stronger global flow acceleration and at smaller Mach numbers.

Item URL in elib:https://elib.dlr.de/127553/
Document Type:Article
Additional Information:September 2019, available online 04. May 2019
Title:Experimental study of bump effects on boundary-layer transition in compressible high Reynolds number flow
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Costantini, Marcomarco.costantini (at) dlr.dehttps://orcid.org/0000-0003-0642-0199
Risius, Steffensteffen.risius (at) dlr.dehttps://orcid.org/0000-0002-5530-9609
Koch, Stefanstefan.koch (at) dlr.deUNSPECIFIED
Fuchs, Carstencarsten.fuchs (at) dlr.deUNSPECIFIED
Gerhard, Uweuwe.gerhard (at) dlr.deUNSPECIFIED
Hein, StefanStefan.Hein (at) dlr.deUNSPECIFIED
Klein, Christianchristian.klein (at) dlr.dehttps://orcid.org/0000-0001-7592-6922
Date:September 2019
Journal or Publication Title:Experimental Thermal and Fluid Science
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:106
DOI :10.1016/j.expthermflusci.2019.04.027
Page Range:pp. 234-254
Editors:
EditorsEmail
Kähler, Christianchristian.kaehler@unibw.de
Publisher:Elsevier
Series Name:Special Issue dedicated to the 5th International Conference on Experimental Fluid Mechanics (ICEFM)
ISSN:0894-1777
Status:Published
Keywords:Bump, Transition, Temperature-Sensitive Paint, Boundary Layer
Institution:Deutsches Zentrum für Luft- und Raumfahrt e.V.
Department:AS-EXV
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
Institute for Aerodynamics and Flow Technology > High Speed Configurations, GO
Deposited By: Micknaus, Ilka
Deposited On:25 Jun 2019 15:03
Last Modified:06 Sep 2019 15:25

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