{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,4]],"date-time":"2026-02-04T16:46:31Z","timestamp":1770223591906,"version":"3.49.0"},"reference-count":28,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2022,1,15]],"date-time":"2022-01-15T00:00:00Z","timestamp":1642204800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","award":["PAK 948"],"award-info":[{"award-number":["PAK 948"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]},{"name":"DLR Project","award":["SuperCOOL"],"award-info":[{"award-number":["SuperCOOL"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this paper, the authors demonstrate the application of a modified Ru(phen)-based temperature-sensitive paint which was originally developed for the evaluation of unsteady aero-thermodynamic phenomena in high Mach number but short duration experiments. In the present work, the modified TSP with a temperature sensitivity of up to \u22125.6%\/K was applied in a low Mach number long-duration test case in a low-pressure environment. For the demonstration of the paint\u2019s performance, a flat plate with a mounted cylinder was set up in the High-Speed Cascade Wind Tunnel (HGK). The test case was designed to generate vortex shedding frequencies up to 4300 Hz which were sampled using a high-speed camera at 40 kHz frame rate to resolve unsteady surface temperature fields for potential heat-transfer estimations. The experiments were carried out at reduced ambient pressure of p\u221e = 13.8 kPa for three inflow Mach numbers being Ma\u221e=[0.3;0.5;0.7]. In order to enable the resolution of very low temperature fluctuations down to the noise floor of 10\u22125 K with high spatial and temporal resolution, the flat plate model was equipped with a sprayable carbon nanotube (CNT) heating layer. This constellation, together with the thermal sensors incorporated in the model, allowed for the calculation of a quasi-heat-transfer coefficient from the surface temperature fields. Besides the results of the experiments, the paper highlights the properties of the modified TSP as well as the methodology.<\/jats:p>","DOI":"10.3390\/s22020657","type":"journal-article","created":{"date-parts":[[2022,1,16]],"date-time":"2022-01-16T20:45:21Z","timestamp":1642365921000},"page":"657","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["An Ultra-Fast TSP on a CNT Heating Layer for Unsteady Temperature and Heat Flux Measurements in Subsonic Flows"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5203-8068","authenticated-orcid":false,"given":"Martin","family":"Bitter","sequence":"first","affiliation":[{"name":"Institute of Jet Propulsion, Bundeswehr University Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2881-7130","authenticated-orcid":false,"given":"Michael","family":"Hilfer","sequence":"additional","affiliation":[{"name":"Institute of Aerodynamics and Flow Technology, German Aerospace Center, Bunsenstra\u00dfe 10, 37073 G\u00f6ttingen, Germany"}]},{"given":"Tobias","family":"Schubert","sequence":"additional","affiliation":[{"name":"Institute of Jet Propulsion, Bundeswehr University Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7592-6922","authenticated-orcid":false,"given":"Christian","family":"Klein","sequence":"additional","affiliation":[{"name":"Institute of Aerodynamics and Flow Technology, German Aerospace Center, Bunsenstra\u00dfe 10, 37073 G\u00f6ttingen, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2368-2510","authenticated-orcid":false,"given":"Reinhard","family":"Niehuis","sequence":"additional","affiliation":[{"name":"Institute of Jet Propulsion, Bundeswehr University Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2022,1,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Liu, T., Sullivan, J.P., Asai, K., Klein, C., and Egami, Y. 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