Heat transfer and film cooling measurements on aerodynamic geometries relevant for turbomachinery

Abstract A measurement technique for recording convective heat transfer coefficient and adiabatic film cooling effectiveness in demanding environments with highly curved surfaces and limited optical access, such as turbomachinery, is presented. Thermography and tailor-made flexible heating foils are...

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Autores principales:	Patrick Jagerhofer, Jakob Woisetschläger, Gerhard Erlacher, Emil Göttlich
Formato:	article
Lenguaje:	EN
Publicado:	Springer 2021
Materias:	Heat transfer Film cooling Turbomachinery Infrared thermography Heating foil Calibration Science Q Technology T
Acceso en línea:	https://doaj.org/article/41b17c369d5b452eb975612e86b92654
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id	oai:doaj.org-article:41b17c369d5b452eb975612e86b92654
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spelling	oai:doaj.org-article:41b17c369d5b452eb975612e86b926542021-11-28T12:13:33ZHeat transfer and film cooling measurements on aerodynamic geometries relevant for turbomachinery10.1007/s42452-021-04845-52523-39632523-3971https://doaj.org/article/41b17c369d5b452eb975612e86b926542021-11-01T00:00:00Zhttps://doi.org/10.1007/s42452-021-04845-5https://doaj.org/toc/2523-3963https://doaj.org/toc/2523-3971Abstract A measurement technique for recording convective heat transfer coefficient and adiabatic film cooling effectiveness in demanding environments with highly curved surfaces and limited optical access, such as turbomachinery, is presented. Thermography and tailor-made flexible heating foils are used in conjunction with a novel multistep calibration and data reduction method. This method compensates for sensor drift, angle dependence of surface emissivity and window transmissivity, heat flux inhomogeneity, and conductive losses. The 2D infrared images are mapped onto the 3D curved surfaces and overlapped, creating surface maps of heat transfer coefficient and film cooling effectiveness covering areas significantly larger than the window size. The measurement technique’s capability is demonstrated in a sector-cascade test rig of a turbine center frame (TCF), an inherent component of modern two-spool turbofan engines. The horseshoe vortices were found to play a major role for the thermal integrity of turbine center frames, as they lead to a local increase in heat transfer, and at the same instance, to a reduction of film cooling effectiveness. It was also found that the horseshoe vortices lift off from the curved surface at 50% hub length, resulting in a pair of counter-rotating vortices. The measurement technique was validated by comparing the data against flat plate correlations and also by the linear relation between temperature difference and heat flux. This study is complemented with an extensive error and uncertainty analysis. Article highlights This paper presents an accurate measurement technique for heat transfer and film cooling on 3D curved surfaces with limited optical access using flexible tailor-made heating foils, infrared thermography and a high-fidelity multistep calibration process. Graphical abstractPatrick JagerhoferJakob WoisetschlägerGerhard ErlacherEmil GöttlichSpringerarticleHeat transferFilm coolingTurbomachineryInfrared thermographyHeating foilCalibrationScienceQTechnologyTENSN Applied Sciences, Vol 3, Iss 12, Pp 1-16 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Heat transfer Film cooling Turbomachinery Infrared thermography Heating foil Calibration Science Q Technology T
spellingShingle	Heat transfer Film cooling Turbomachinery Infrared thermography Heating foil Calibration Science Q Technology T Patrick Jagerhofer Jakob Woisetschläger Gerhard Erlacher Emil Göttlich Heat transfer and film cooling measurements on aerodynamic geometries relevant for turbomachinery
description	Abstract A measurement technique for recording convective heat transfer coefficient and adiabatic film cooling effectiveness in demanding environments with highly curved surfaces and limited optical access, such as turbomachinery, is presented. Thermography and tailor-made flexible heating foils are used in conjunction with a novel multistep calibration and data reduction method. This method compensates for sensor drift, angle dependence of surface emissivity and window transmissivity, heat flux inhomogeneity, and conductive losses. The 2D infrared images are mapped onto the 3D curved surfaces and overlapped, creating surface maps of heat transfer coefficient and film cooling effectiveness covering areas significantly larger than the window size. The measurement technique’s capability is demonstrated in a sector-cascade test rig of a turbine center frame (TCF), an inherent component of modern two-spool turbofan engines. The horseshoe vortices were found to play a major role for the thermal integrity of turbine center frames, as they lead to a local increase in heat transfer, and at the same instance, to a reduction of film cooling effectiveness. It was also found that the horseshoe vortices lift off from the curved surface at 50% hub length, resulting in a pair of counter-rotating vortices. The measurement technique was validated by comparing the data against flat plate correlations and also by the linear relation between temperature difference and heat flux. This study is complemented with an extensive error and uncertainty analysis. Article highlights This paper presents an accurate measurement technique for heat transfer and film cooling on 3D curved surfaces with limited optical access using flexible tailor-made heating foils, infrared thermography and a high-fidelity multistep calibration process. Graphical abstract
format	article
author	Patrick Jagerhofer Jakob Woisetschläger Gerhard Erlacher Emil Göttlich
author_facet	Patrick Jagerhofer Jakob Woisetschläger Gerhard Erlacher Emil Göttlich
author_sort	Patrick Jagerhofer
title	Heat transfer and film cooling measurements on aerodynamic geometries relevant for turbomachinery
title_short	Heat transfer and film cooling measurements on aerodynamic geometries relevant for turbomachinery
title_full	Heat transfer and film cooling measurements on aerodynamic geometries relevant for turbomachinery
title_fullStr	Heat transfer and film cooling measurements on aerodynamic geometries relevant for turbomachinery
title_full_unstemmed	Heat transfer and film cooling measurements on aerodynamic geometries relevant for turbomachinery
title_sort	heat transfer and film cooling measurements on aerodynamic geometries relevant for turbomachinery
publisher	Springer
publishDate	2021
url	https://doaj.org/article/41b17c369d5b452eb975612e86b92654
work_keys_str_mv	AT patrickjagerhofer heattransferandfilmcoolingmeasurementsonaerodynamicgeometriesrelevantforturbomachinery AT jakobwoisetschlager heattransferandfilmcoolingmeasurementsonaerodynamicgeometriesrelevantforturbomachinery AT gerharderlacher heattransferandfilmcoolingmeasurementsonaerodynamicgeometriesrelevantforturbomachinery AT emilgottlich heattransferandfilmcoolingmeasurementsonaerodynamicgeometriesrelevantforturbomachinery
_version_	1718408133558140928

Heat transfer and film cooling measurements on aerodynamic geometries relevant for turbomachinery

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