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The Tip Vortex System of a Four-Bladed Rotor in Dynamic Stall Conditions

Wolf, C. Christian and Braukmann, Johannes N. and Stauber, Wolfgang and Schwermer, Till and Raffel, Markus (2018) The Tip Vortex System of a Four-Bladed Rotor in Dynamic Stall Conditions. In: AHS International 74th Annual Forum & Technology 2018. AHS International 74th Annual Forum & Technology Display, 14.-17. Mai 2018, Phoenix, Arizona USA.

Full text not available from this repository.

Official URL: https://vtol.org/events/forum-74

Abstract

The tip vortex-system downstream of a four-bladed instrumented rotor was investigated experimentally through the application of stereoscopic particle image velocimetry (PIV). A dynamic stall test case was facilitated by a high cyclic pitch setting of the swashplate, with additional attached-flow and constant-pitch test cases for comparison reasons. The phase-locked PIV system and a rotation of the swashplate assembly allowed for an acquisition of the tip vortex system over the entire dynamic stall cycle and vortex ages up to at least 235 degree. The vortex structure and its relation to the blade shear layers were studied by means of both phase-averaged flow fields and the identification of vortex properties such as circulation and swirl velocity distributions. When approaching dynamic stall, a break-down of the vortex structure started at high vortex ages, accompanied by the entrainment of turbulent structures from the passing blade shear layers into the tip vortices. After the flow over the blade is fully separated and during large parts of the downstroke, the wake of the rotor tips appeared as a highly turbulent area with no individual tip vortices traceable, before reestablishing an ordered tip vortex structure shortly before the minimum blade pitch angle.

Item URL in elib:https://elib.dlr.de/127163/
Document Type:Conference or Workshop Item (Speech)
Title:The Tip Vortex System of a Four-Bladed Rotor in Dynamic Stall Conditions
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Wolf, C. ChristianChristian.Wolf (at) dlr.dehttps://orcid.org/0000-0002-9052-7548
Braukmann, Johannes N.Johannes.Braukmann (at) dlr.dehttps://orcid.org/0000-0001-8046-9623
Stauber, WolfgangUNSPECIFIEDUNSPECIFIED
Schwermer, TillTill.Schwermer (at) alumni-uni-hannover.dehttps://orcid.org/0000-0002-6918-4480
Raffel, Markusmarkus.raffel (at) dlr.dehttps://orcid.org/0000-0002-3340-9115
Date:2018
Journal or Publication Title:AHS International 74th Annual Forum & Technology 2018
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:Blade Tip Vortex, Particle Image Velocimetry (PIV), Rotor Test Facility
Event Title:AHS International 74th Annual Forum & Technology Display
Event Location:Phoenix, Arizona USA
Event Type:international Conference
Event Dates:14.-17. Mai 2018
Organizer:American Helicopter Society
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:24 Apr 2019 08:50
Last Modified:24 Apr 2019 08:50

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