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Boundary layer transition detection on wind tunnel models during continuous pitch traverse

Klein, Christian and Yorita, Daisuke and Henne, Ulrich and Ondrus, Vladimir and Beifuss, Uwe and Hensch, Ann-Katrin and Longo, Roberto (2019) Boundary layer transition detection on wind tunnel models during continuous pitch traverse. In: AIAA Scitech Forum, 2019 (1180), pp. 1-10. AIAA. AIAA Science and Technology Forum AIAA SciTech 2019, 07.-11. Jan. 2019, San Diego, California, USA. DOI: 10.2514/6.2019-1180 ISBN 978-162410578-4

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Official URL: https://doi.org/10.2514/6.2019-1180

Abstract

For aerodynamic profile tests on aircraft models, boundary-layer transition detection is of great interest. Under ambient flow conditions the infrared technique (IR) is a well-established image-based method for this purpose. In high Reynolds number tests that are conducted at cryogenic temperatures the IR technique is of only limited suitability. In contrast, the image-based Temperature-Sensitive Paint (TSP) technique is well suited for these conditions. Boundary layer transition detection by means of TSP generally requires an artificial temperature difference between model surface and flow. For wind tunnels operated under cryogenic conditions changing the liquid nitrogen injection rate of the working fluid causing a rapid change of the flow temperature can generate this temperature difference (“temperature-step method”). The drawback of this temperature-step method is that during the change of the flow temperature neither the Reynolds nor the Mach number can be kept constant. To overcome this problem, we have recently published an alternative approach where Carbon Nanotubes (CNT) are used to electrically heat the model surface and thus generate a well-defined temperature difference to visualize laminar-turbulent transition. The combination of CNT and TSP, which we call cntTSP, delivered excellent results in different wind tunnel tests from ambient temperatures down to 100 K. The cntTSP sensor visualizes the surface boundary-layer conditions as temperature distribution based on different heat transfer coefficients in the laminar and turbulent flow. Compared to the temperature-step method the cntTSP approach has the advantage and potential to measure boundary-layer transition in a time-resolved manner, e.g. on wind tunnel models when the wind tunnel is operated in continuous pitch traverse mode, which is desired in order to improve the data productivity of the wind tunnel tests. In this paper, the applicability of cntTSP to a continuous moving model (pitch-traverse or pitch-sweep test) is investigated in the pilot facility of the European Transonic Windtunnel (PETW). The laminar to turbulent boundary-layer transition appearing on a 2D model is visualized and compared between the pitch-traverse and pitch-pause tests.

Item URL in elib:https://elib.dlr.de/126634/
Document Type:Conference or Workshop Item (Speech)
Additional Information:AIAA-2019-1180
Title:Boundary layer transition detection on wind tunnel models during continuous pitch traverse
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Klein, Christianchristian.klein (at) dlr.dehttps://orcid.org/0000-0001-7592-6922
Yorita, Daisukedaisuke.yorita (at) dlr.deUNSPECIFIED
Henne, Ulrichulrich.henne (at) dlr.deUNSPECIFIED
Ondrus, Vladimirvondrus (at) yahoo.comUNSPECIFIED
Beifuss, Uweuwe.beifuss (at) uni-hohenheim.deUNSPECIFIED
Hensch, Ann-Katrinakh (at) etw.deUNSPECIFIED
Longo, Robertorlo (at) etw.deUNSPECIFIED
Date:January 2019
Journal or Publication Title:AIAA Scitech Forum, 2019
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:No
DOI :10.2514/6.2019-1180
Page Range:pp. 1-10
Publisher:AIAA
Series Name:Conference Proceedings online
ISBN:978-162410578-4
Status:Published
Keywords:Temperature-sensitive paint, continous pitch traverse, Transition, CAST-10-2, TSP, CNT, PETW, cntTSP
Event Title:AIAA Science and Technology Forum AIAA SciTech 2019
Event Location:San Diego, California, USA
Event Type:international Conference
Event Dates:07.-11. Jan. 2019
Organizer:AIAA
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
Deposited By: Micknaus, Ilka
Deposited On:04 Mar 2019 03:54
Last Modified:02 Aug 2019 13:20

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