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Aperiodicity in the near field of full-scale rotor blade tip vortices

Kindler, Kolja and Mulleners, Karen and Richard, Hugues and van der Wall, Berend G. and Raffel, Markus (2011) Aperiodicity in the near field of full-scale rotor blade tip vortices. Experiments in Fluids, Vol. 5 (6), pp. 1601-1610. Springer Verlag, Heidelberg. DOI: 10.1007/s00348-010-1016-8. ISSN 0723-4864.

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Abstract

Blade tip vortices are the dominant vortical structures of the helicopter flow field. The inherent complexity of the vortex dynamics has led to an increasing interest in full-scale in situ experiments, where the near field, closely behind the blade, is of particular interest, since measures of vortex control mostly target this initial stage of development. To examine the near field, threecomponent particle image velocimetry (PIV) measurements of blade tip vortices of a full-scale helicopter in simulated hover flight in ground effect were conducted. A feasible and robust evaluation procedure was developed to minimise the shortcomings of full-scale PIV applications, such as a moderate spatial resolution and an elevated measurement noise level. At vortex ages ranging from 1° to 30°, a pronounced aperiodicity and asymmetry of the vortex were observed in -sections perpendicular to the vortex axes. At 1°, a preferential orientation of the vortex was observed. For increasing wake age, vortex wandering increased while the asymmetry of the vortex cores decreased. The high level of aperiodicity and core asymmetry must be taken into account when considering phase-averaged vortex characteristics in the near wake region.

Document Type:Article
Additional Information:Published online: 12. Dec. 2010
Title:Aperiodicity in the near field of full-scale rotor blade tip vortices
Authors:
AuthorsInstitution or Email of Authors
Kindler, Koljakkindler@mpi-bremen.de
Mulleners, Karenmulleners@tfd.uni-hannover.de, Leibniz Universität Hannover, Hannover
Richard, HuguesDLR
van der Wall, Berend G.Berend.vanderWall@dlr.de
Raffel, Markusmarkus.raffel@dlr.de
Date:2011
Journal or Publication Title:Experiments in Fluids
Refereed publication:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:Vol. 5
DOI:10.1007/s00348-010-1016-8
Page Range:pp. 1601-1610
Publisher:Springer Verlag, Heidelberg
ISSN:0723-4864
Status:Published
Keywords:full-scale, PIV, blade tip vortex
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: Braunschweig , Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Fluid Systems
Institute of Aerodynamics and Flow Technology > Helicopters
Institute of Flight Systems > Rotorcraft
Deposited By: Karen Mulleners
Deposited On:01 Jun 2011 14:52
Last Modified:25 Apr 2014 14:18

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