Wolf, Christian und Weiss, Armin und Schwarz, Clemens und Braukmann, Johannes N. und Koch, Stefan und Raffel, Markus (2021) Wake Unsteadiness and Tip Vortex System of Full–Scale Helicopters in Ground Effect. In: 77th Annual Vertical Flight Society Forum and Technology Display: The Future of Vertical Flight, FORUM 2021. Vertical Flight Society's 77th Annual Forum 2021, 2021-05-10 - 2021-05-14, Virtuell. ISBN 978-171383001-6.
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Offizielle URL: https://vtol.org/annual-forum/forum-77-proceedings-and-access
Kurzfassung
The main rotor wake of free–flying helicopters in ground effect was investigated during a measurement campaign with the DLR test rotorcraft Airbus Bo105 and EC135. An advanced measurement system combined high–speed schlieren imaging with point–wise constant temperature anemometry for a comprehensive analysis of the flow. In hover conditions, the wake structure was similar to earlier data, in spite of the environmental conditions, which were found to have a significant influence. The schlieren system tracked the blade tip vortices convecting along the slipstream boundary. Depending on the rotorcraft, the vortices developed either instabilities of individual filaments or cooperative pairing instabilities. Both instability types occurred one to two revolutions below the rotor plane, and the decayed tip vortices fell below the schlieren sensitivity limit soon after. The velocity footprint of the vortices was detected by fiber–film sensors further downstream along the slipstream boundary, but harmonic oscillations play a minor role in comparison to broad–banded turbulence with a Kolmogorov–like spectrum. The wake was found to be hover–like for vertical take–off cases until breaking down into low–frequency oscillations when exceeding a hub height of approximately 1.4 rotor radii. In forward flight conditions, blade–vortex interactions were found in the frontal area of the main rotor plane, and between the main rotor tip vortices and the Bo105’s tail rotor.
elib-URL des Eintrags: | https://elib.dlr.de/141956/ | ||||||||||||||||||||||||||||
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Dokumentart: | Konferenzbeitrag (Vortrag) | ||||||||||||||||||||||||||||
Titel: | Wake Unsteadiness and Tip Vortex System of Full–Scale Helicopters in Ground Effect | ||||||||||||||||||||||||||||
Autoren: |
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Datum: | Mai 2021 | ||||||||||||||||||||||||||||
Erschienen in: | 77th Annual Vertical Flight Society Forum and Technology Display: The Future of Vertical Flight, FORUM 2021 | ||||||||||||||||||||||||||||
Referierte Publikation: | Ja | ||||||||||||||||||||||||||||
Open Access: | Nein | ||||||||||||||||||||||||||||
Gold Open Access: | Nein | ||||||||||||||||||||||||||||
In SCOPUS: | Ja | ||||||||||||||||||||||||||||
In ISI Web of Science: | Nein | ||||||||||||||||||||||||||||
ISBN: | 978-171383001-6 | ||||||||||||||||||||||||||||
Status: | veröffentlicht | ||||||||||||||||||||||||||||
Stichwörter: | Helicopter, Rotor Wake, Background Oriented Schlieren, Constant Temperature Anemometry, Full-Scale Testing, Blade Tip Vortex | ||||||||||||||||||||||||||||
Veranstaltungstitel: | Vertical Flight Society's 77th Annual Forum 2021 | ||||||||||||||||||||||||||||
Veranstaltungsort: | Virtuell | ||||||||||||||||||||||||||||
Veranstaltungsart: | internationale Konferenz | ||||||||||||||||||||||||||||
Veranstaltungsbeginn: | 10 Mai 2021 | ||||||||||||||||||||||||||||
Veranstaltungsende: | 14 Mai 2021 | ||||||||||||||||||||||||||||
Veranstalter : | Vertical Flight Society | ||||||||||||||||||||||||||||
HGF - Forschungsbereich: | Luftfahrt, Raumfahrt und Verkehr | ||||||||||||||||||||||||||||
HGF - Programm: | Luftfahrt | ||||||||||||||||||||||||||||
HGF - Programmthema: | Effizientes Luftfahrzeug | ||||||||||||||||||||||||||||
DLR - Schwerpunkt: | Luftfahrt | ||||||||||||||||||||||||||||
DLR - Forschungsgebiet: | L EV - Effizientes Luftfahrzeug | ||||||||||||||||||||||||||||
DLR - Teilgebiet (Projekt, Vorhaben): | L - Virtueller Hubschrauber und Validierung | ||||||||||||||||||||||||||||
Standort: | Göttingen | ||||||||||||||||||||||||||||
Institute & Einrichtungen: | Institut für Aerodynamik und Strömungstechnik > Hubschrauber, GO Institut für Aerodynamik und Strömungstechnik > Hochgeschwindigkeitskonfigurationen, GO | ||||||||||||||||||||||||||||
Hinterlegt von: | Carter, Beatrice | ||||||||||||||||||||||||||||
Hinterlegt am: | 14 Jul 2021 14:51 | ||||||||||||||||||||||||||||
Letzte Änderung: | 31 Okt 2024 10:11 |
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