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Thermographic Flow Visualization by means of Non-negative Matrix Factorization

Gleichauf, D. and Dollinger, Christoph and Balaresque, Nicholas and Gardner, Anthony D. and Sorg, M. and Fischer, Andreas (2020) Thermographic Flow Visualization by means of Non-negative Matrix Factorization. International Journal of Heat and Fluid Flow, 82, pp. 1-11. Elsevier. doi: 10.1016/j.ijheatfluidflow.2019.108528. ISSN 0142-727X.

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Official URL: https://doi.org/10.1016/j.ijheatfluidflow.2019.108528


In order to investigate the areas of different flow regimes in the boundary layer of an airfoil, thermography is a powerful flow visualization tool. However, the distinguishability between boundary layer flow regimes such as laminar or turbulent is limited due to systematic and random inhomogeneity in the measured temperature field, hindering a clear separation of the flow regimes. In order to increase the distinguishability of different flow regimes, a time series of thermographic images is evaluated by means of a non-negative matrix factorization. As a result, the non-negative matrix factorization creates images that contain the dominant features of the measured images, while reducing systematic temperature gradients within the flow regimes by up to a factor of five. This way an increase of the distinguishability between every pair of consecutive flow regimes can be achieved on the surface of a non-heated cylinder in cross-flow condition. As a further application example of the non-negative matrix factorization, the distinguishability between the flow and the laminar-turbulent transition zone on a heated helicopter airfoil is also increased by a factor of five. Hence, non-negative matrix factorization is capable of enhancing thermographic flow visualization for increasing the distinguishability of different flow phenomena.

Item URL in elib:https://elib.dlr.de/134217/
Document Type:Article
Title:Thermographic Flow Visualization by means of Non-negative Matrix Factorization
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Gleichauf, D.Universität BremenUNSPECIFIEDUNSPECIFIED
Dollinger, ChristophUniversität Bremenhttps://orcid.org/0000-0002-0679-5073UNSPECIFIED
Balaresque, NicholasDeutsche WindGuard Engineering GmbH, BremerhavenUNSPECIFIEDUNSPECIFIED
Gardner, Anthony D.UNSPECIFIEDhttps://orcid.org/0000-0002-1176-3447UNSPECIFIED
Fischer, AndreasUniversität Bremenhttps://orcid.org/0000-0001-7349-7722UNSPECIFIED
Date:21 February 2020
Journal or Publication Title:International Journal of Heat and Fluid Flow
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 1-11
EditorsEmailEditor's ORCID iDORCID Put Code
Keywords:thermographic flow visualization, boundary layer measurement, computer vision, temperature inhomogeneity, non-negative matrix factorization, contrast enhancement
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:rotorcraft
DLR - Research area:Aeronautics
DLR - Program:L RR - Rotorcraft Research
DLR - Research theme (Project):L - The Virtual Aerodynamic Rotorcraft (old)
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Helicopter, GO
Deposited By: Winkels, Elisabeth
Deposited On:18 Mar 2020 12:25
Last Modified:18 Mar 2020 12:27

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