Optimisation of Differential Infrared Thermography for Unsteady Boundary Layer Transition Measurement

C. Christian Wolf, Christoph Mertens, Anthony D. Gardner, Christoph Dollinger, Andreas Fischer

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientific

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Abstract

Differential infrared thermography (DIT) is a method of analyzing infrared images to measure the unsteady motion of the laminar–turbulent transition of a boundary layer. It uses the subtraction of two infrared images taken with a short time delay. DIT is a new technique which already demonstrated its validity in
applications related to the unsteady aerodynamics of helicopter rotors in forward 2ight. The current study investigates a pitch–oscillating airfoil and proposes several optimizations of the original concept. These include the extension of DIT to steady test cases, a temperature compensation for long–term measurements,
and a discussion of the proper infrared image separation distance. The current results also provide a deeper insight into the working principles of the technique. The results compare well to reference data acquired by unsteady pressure transducers, but at least for the current setup DIT results in an additional measurement–related lag for relevant pitching frequencies.
Original languageEnglish
Title of host publication44th European Rotorcraft Forum
PublisherEuropean Rotorcraft Forum (ERF)
Number of pages14
Publication statusPublished - Sep 2018
Event44th European Rotorcraft Forum - Delft, Netherlands
Duration: 18 Sep 201821 Sep 2018
Conference number: 44

Conference

Conference44th European Rotorcraft Forum
Abbreviated titleERF 2018
CountryNetherlands
CityDelft
Period18/09/1821/09/18

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