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Aerodynamic Results from the Star Hover Test: An Examination of Active Twist Actuation

Bauknecht, Andre and Ewers, Benjamin and Schneider, Oliver and Raffel, Markus (2015) Aerodynamic Results from the Star Hover Test: An Examination of Active Twist Actuation. 41st European Rotorcraft Forum 2015, 01. - 04. Sept. 2015, Munich, Germany..

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Official URL: http://www.erf2015.dglr.de/


Active rotor control concepts, such as active twist actuation, have the potential to effectively reduce the noise and vibrations of helicopter rotors. Within the STAR (Smart Twisting Active Rotor) hover test, an active twist rotor was tested in the rotor preparation hall at DLR Braunschweig. The rotor blades were actuated with frequencies of 1/rev – 5/rev and peak torsion amplitudes of up to 2°. This paper describes aerodynamic results from the hover test based on time-resolved stereoscopic PIV measurements at the forward blade tip position. Continuous time series of flow fields behind the blade tips were evaluated to investigate the young blade tip vortices between 3.56° and 45.74° of vortex age. For the unactuated baseline case, the vortex trajectory, blade tip scattering, and temporal development of the peak axial and swirl velocity are discussed. The effects of the active twist actuation on the blade tip vortices are examined for the 1/rev and 3/rev actuation frequencies. The variation of the vortex trajectories is dominated by the blade tip deflection for the 1/rev actuation, and by the torsion of the blade tip for the 3/rev actuation. The 3/rev actuation reduces the initial peak swirl velocity by up to 35% compared to the baseline case. The actuation with the control phase angles 225° – 315° achieves a strong variation of the vortex trajectories with a vertical deviation of up to 2.6%R below the rotor tip path plane. The present aerodynamic investigation reveals a high control authority of the actuators – especially for the 3/rev actuation frequency – on the vortex trajectories and the vortex strength, thus demonstrating the usefulness of the active twist concept.

Item URL in elib:https://elib.dlr.de/97366/
Document Type:Conference or Workshop Item (Speech)
Additional Information:ERF2015_0080
Title:Aerodynamic Results from the Star Hover Test: An Examination of Active Twist Actuation
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Page Range:pp. 1-16
Series Name:Conference Proceedings online
Keywords:STAR; Highspeed PIV; Blade tip vortex; Wirbel; Active Twist; Actuation
Event Title:41st European Rotorcraft Forum 2015
Event Location:Munich, Germany.
Event Type:international Conference
Event Dates:01. - 04. Sept. 2015
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: Braunschweig , Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Helicopters
Institute of Flight Systems > Rotorcraft
Deposited By: Micknaus, Ilka
Deposited On:05 Oct 2015 14:47
Last Modified:15 Oct 2015 08:41

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