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Experimental and Numerical Investigations of Unsteady Boundary-Layer Transition on a Dynamically Pitching Subscale Helicopter Rotor Blade

Weiss, Armin and Braukmann, Johannes N. and Kaufmann, Kurt (2019) Experimental and Numerical Investigations of Unsteady Boundary-Layer Transition on a Dynamically Pitching Subscale Helicopter Rotor Blade. In: 19th ONERA-DLR Aerospace Symposium (ODAS 2019). ODAS 2019, 19th ONERA-DLR Aerospace Symposium, 3.-5. Juni 2019, Meudon, France.

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Official URL: https://w3.onera.fr/odas/content/programme

Abstract

The presented work tackles the lack of experimental investigations of unsteady boundary-layer transition on rotor blades at cyclic pitch actuation, which are important for accurate performance predictions, for instance for helicopters in forward flight. Unsteady boundary-layer 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), which does not require instrumented rotor blades. Experiments were conducted at rotation rates corresponding to Mach and Reynolds numbers at 75% rotor radius of M_75 = 0.11, 0.22 and Re_75=10*5 = 1.7, 3.5 and at varying cyclic blade pitch settings. The setup allowed to sample boundary-layer transition across the outer 55% of the rotor radius. The study is complemented by numerical simulations including boundary-layer transition modelling based on semi-empirical transition criteria. For the first time, the work successfully applies DIT to capture unsteady boundary-layer transition on the blade suction side on rotating blades. Promising results reveal a plausible development of detected boundary-layer transition positions over the pitch cycle, a reasonable comparison to experimental results obtained using the established sigma c_p method and noticeable agreement to numerical simulations.

Item URL in elib:https://elib.dlr.de/127485/
Document Type:Conference or Workshop Item (Speech)
Title:Experimental and Numerical Investigations of Unsteady Boundary-Layer Transition on a Dynamically Pitching Subscale Helicopter Rotor Blade
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Weiss, Arminarmin.weiss (at) dlr.dehttps://orcid.org/0000-0002-7532-2974
Braukmann, Johannes N.Johannes.Braukmann (at) dlr.dehttps://orcid.org/0000-0001-8046-9623
Kaufmann, KurtKurt.Kaufmann (at) dlr.dehttps://orcid.org/0000-0003-2276-3386
Date:June 2019
Journal or Publication Title:19th ONERA-DLR Aerospace Symposium (ODAS 2019)
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:unsteady boundary-layer transition, rotor blades, differential infrared thermography (DIT), numerical simulations, helicopter
Event Title:ODAS 2019, 19th ONERA-DLR Aerospace Symposium
Event Location:Meudon, France
Event Type:international Conference
Event Dates:3.-5. Juni 2019
Organizer:DLR/ONERA
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
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Helicopter, GO
Deposited By: Winkels, Elisabeth
Deposited On:12 Jun 2019 12:12
Last Modified:31 Jul 2019 20:25

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