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Unsteady Boundary-Layer Transition Measurements and Computations on a Rotating Blade under Cyclic Pitch Conditions

Weiss, Armin and Wolf, C. Christian and Kaufmann, Kurt and Braukmann, Johannes N. and Raffel, Markus and Heineck, James T. (2019) Unsteady Boundary-Layer Transition Measurements and Computations on a Rotating Blade under Cyclic Pitch Conditions. In: 45th European Rotorcraft Forum ERF 2019. 45th European Rotorcraft Forum ERF 2019, 2019-09-17 - 2019-09-20, Warschau, Polen.

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Official URL: http://erf2019.pw.edu.pl/


The presented work tackles the lack of experimental investigations of unsteady laminar-turbulent boundary-layer transition on rotor blades at cyclic pitch actuation, which are important for accurate performance predictions of helicopters in forward flight. Unsteady transition positions were measured on the blade suction side of a four-bladed subscale rotor by means of the non-intrusive Differential Infrared Thermography (DIT). Experiments were conducted at different rotation rates corresponding to Mach and Reynolds numbers at 75% rotor radius of up to M_75 = 0.21 and Re_75 = 3.3 x 10*5 and with varying cyclic blade pitch settings. The setup allowed to measure transition across the outer 54% of the rotor radius. For comparison, transition was also measured using conventional infrared thermography for steady cases with collective pitch settings only. The study is complemented by numerical simulations including boundary-layer transition modelling based on semi-empirical criteria. Promising results reveal a plausible development of measured transition positions over the pitch cycle, a reasonable comparison to experimental results obtained using the already established sigma c_p method, and noticeable agreement with numerical simulations. The result is the first systematic study of unsteady boundary-layer transition on a rotor suction side by means of DIT including a comparison to numerical computations.

Item URL in elib:https://elib.dlr.de/126548/
Document Type:Conference or Workshop Item (Speech)
Title:Unsteady Boundary-Layer Transition Measurements and Computations on a Rotating Blade under Cyclic Pitch Conditions
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Weiss, ArminUNSPECIFIEDhttps://orcid.org/0000-0002-7532-2974UNSPECIFIED
Wolf, C. ChristianUNSPECIFIEDhttps://orcid.org/0000-0002-9052-7548UNSPECIFIED
Kaufmann, KurtUNSPECIFIEDhttps://orcid.org/0000-0003-2276-3386UNSPECIFIED
Braukmann, Johannes N.UNSPECIFIEDhttps://orcid.org/0000-0001-8046-9623UNSPECIFIED
Raffel, MarkusUNSPECIFIEDhttps://orcid.org/0000-0002-3340-9115133716062
Heineck, James T.NASA Ames Research Center, Moffett Field, CA, USAUNSPECIFIEDUNSPECIFIED
Date:September 2019
Journal or Publication Title:45th European Rotorcraft Forum ERF 2019
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Keywords:Boundary layer transition, differential infrared thermography, rotor performance
Event Title:45th European Rotorcraft Forum ERF 2019
Event Location:Warschau, Polen
Event Type:international Conference
Event Start Date:17 September 2019
Event End Date:20 September 2019
Organizer:Politechnika Warszawska, ITLiMS
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:rotorcraft
DLR - Research area:Aeronautics
DLR - Program:L RR - Rotorcraft Research
DLR - Research theme (Project):L - The Virtual Aerodynamic Rotorcraft (old)
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Helicopter, GO
Deposited By: Winkels, Elisabeth
Deposited On:26 Sep 2019 10:10
Last Modified:24 Apr 2024 20:30

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