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Combining Simultaneous Density and Velocity Measurements of Rotor Blade Tip Vortices under Cyclic Pitch Conditions

Braukmann, Johannes N. and Goerttler, Andreas and Wolf, Christian and Schwarz, Clemens and Raffel, Markus (2021) Combining Simultaneous Density and Velocity Measurements of Rotor Blade Tip Vortices under Cyclic Pitch Conditions. In: Vertical Flight Society's 77th Annual Forum and Technology Display. Vertical Flight Society's 77th Annual Forum 2021, 10.-14. Mai 2021, Virtuell.

Full text not available from this repository.

Official URL: https://vtol.org/annual-forum/forum-77-proceedings-and-access

Abstract

An investigation on blade tip vortices of a sub-scale rotor under cyclic pitch conditions is carried out. Background oriented schlieren (BOS), Particle image velocimetry (PIV), and computational fluid dynamics (CFD) are applied to the same test cases. This approach enables to combine the velocity data from PIV in a measurement plane, the density related data from BOS in a measurement volume and the comprehensive set of flow variables provided by unsteady detached eddy simulations. Vortices up to an age of Ψv = 70◦ in case of PIV and CFD, and up to Ψv = 200◦ in case of BOS are considered. The vortex locations are obtained from all three techniques. The unsteadiness of the vortices was obtained from the experimental results, whereas the CFD provides an average solution. An increased position scatter was observed during the downstroke of the pitch cycle by both experimental methods and in good agreement. In the second part, the PIV velocity data are compared to common vortex models. A link between the density distribution and the swirl velocity is applied to the measured data. Based on the CFD results it is shown that the assumption of isothermal flow yields better agreement between velocity and density than isentropic flow.

Item URL in elib:https://elib.dlr.de/141955/
Document Type:Conference or Workshop Item (Speech)
Title:Combining Simultaneous Density and Velocity Measurements of Rotor Blade Tip Vortices under Cyclic Pitch Conditions
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Braukmann, Johannes N.Johannes.Braukmann (at) dlr.dehttps://orcid.org/0000-0001-8046-9623
Goerttler, AndreasAndreas.Goerttler (at) dlr.deUNSPECIFIED
Wolf, ChristianChristian.Wolf (at) dlr.dehttps://orcid.org/0000-0002-9052-7548
Schwarz, ClemensClemens.Schwarz (at) dlr.deUNSPECIFIED
Raffel, MarkusMarkus.Raffel (at) dlr.dehttps://orcid.org/0000-0002-3340-9115
Date:May 2021
Journal or Publication Title:Vertical Flight Society's 77th Annual Forum and Technology Display
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:BOS, PIV, Vortex, Isentropic, Isothermal, Rotor
Event Title:Vertical Flight Society's 77th Annual Forum 2021
Event Location:Virtuell
Event Type:international Conference
Event Dates:10.-14. Mai 2021
Organizer:Vertical Flight Society
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Efficient Vehicle
DLR - Research area:Aeronautics
DLR - Program:L EV - Efficient Vehicle
DLR - Research theme (Project):L - Virtual Rotorcraft and Validation
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Helicopter, GO
Deposited By: Carter, Beatrice
Deposited On:14 Jul 2021 13:59
Last Modified:14 Jul 2021 15:36

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