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Tip-Vortex Dynamics of a Pitching Rotor Blade-Tip Model

Wolf, C. Christian and Merz, Christoph B. and Richter, Kai and Raffel, Markus (2016) Tip-Vortex Dynamics of a Pitching Rotor Blade-Tip Model. AIAA Journal. American Institute of Aeronautics and Astronautics (AIAA). DOI: 10.2514/1.J054656 ISSN 0001-1452

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Official URL: http://arc.aiaa.org/doi/pdf/10.2514/1.J054656

Abstract

The tip vortex of a finite rotor blade tip model undergoing pitch oscillations is investigated by means of a wind tunnel study. The motion and flow parameters as well as the model geometry were adapted to rotorcraft applications, including test cases with fully attached flow, light dynamic stall, and deep dynamic stall. High–speed Particle Image Velocimetry was used to study the spatio–temporal behavior of the tip wake at different streamwise positions. Combined to surface pressure measurements, the data establishes a connection between the sectional lift of the model and the vortex parameters (for example, swirl velocity and circulation), including dynamic phenomena like hysteresis and vortex breakdown during stalled flow conditions. For pitch oscillations below static stall limit, only small hysteresis effects were observed, and the vortex structure is similar to static reference measurements. Beyond static stall, the tip vortex retains its general structure in a time–averaged or phase–averaged frame, but the instantaneous flow fields reveal an increasing influence of turbulence. Dynamic stall cases exhibit a circulation overshoot beyond static levels during the upstroke and a disorganized and less compact vortex structure during the downstroke.

Item URL in elib:https://elib.dlr.de/103332/
Document Type:Article
Title:Tip-Vortex Dynamics of a Pitching Rotor Blade-Tip Model
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Wolf, C. Christianchristian.wolf (at) dlr.deUNSPECIFIED
Merz, Christoph B.christoph.merz (at) dlr.deUNSPECIFIED
Richter, Kaikai.richter (at) dlr.deUNSPECIFIED
Raffel, Markusmarkus.raffel (at) dlr.deUNSPECIFIED
Date:October 2016
Journal or Publication Title:AIAA Journal
Refereed publication:Yes
Open Access:No
In DOAJ:No
In SCOPUS:Yes
In ISI Web of Science:Yes
DOI :10.2514/1.J054656
Publisher:American Institute of Aeronautics and Astronautics (AIAA)
ISSN:0001-1452
Status:Published
Keywords:Tip Vortex, Dynamic Stall, Particle Image Velocimetry, Unsteady Flows
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:air traffic management and operations
DLR - Research area:Aeronautics
DLR - Program:L AO - Air Traffic Management and Operation
DLR - Research theme (Project):L - Air Transport Concepts and Operation (old)
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Helicopters
Institute of Aerodynamics and Flow Technology > High Speed Configurations
Deposited By: Bachmann, Barbara
Deposited On:22 Sep 2016 13:49
Last Modified:08 Mar 2018 18:42

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