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Session: Novel experimental measurement methods V
Session starts: Thursday 06 November, 14:20
Presentation starts: 14:20
Room: Commission roon 2

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Manuela Sisti (University of Tokyo)
Chiara Falsetti (Delft University of Technology)
Paul Beard (University of Oxford)

Abstract:
This study presents the development of an infrared thermography system aimed at measuring surface temperature and heat transfer on rapidly moving targets, as turbine blades. The system was specifically engineered for the Oxford Turbine Research Facility, a rotating facility capable of matching engine Mach and Reynolds numbers, non-dimensional speed and gas-to-wall temperature ratio. Obtaining reliable infrared thermography data under rotating turbomachinery conditions poses significant challenges due to environmental reflections, low emissivity of metal components, motion-induced blur. Additionally, the transient nature of the test wit a run time of approximately 0.5 s poses challenges related to blade synchronisation and triggering, as well as the impossibility of using frame averaging to reduce random noise. To address these issues, calibration procedures were implemented using a custom-built steady-state experimental rotating rig and referenced against a traceable standard. A method for evaluating the reflected temperature from the environment was also developed and validated. Infrared thermography is utilised to capture temperature distributions across high-pressure turbine blades, enabling evaluation of surface thermal behavior, including high-resolution two-dimensional measurements of surface temperature, adiabatic wall temperature, and Nusselt number are reported for the blade tip and pressure side. Heat transfer thin-film gauges measurements on the blade pressure surface are used to highlight the capabilities of infrared thermography. This technique can be extended to other environments involving fast-moving targets or rapid thermal transients, where accurate surface temperature and heat transfer measurements are critical.