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Investigation of the unsteady flow field inside a leading edge slat cove

Käpernick, Kristian and Koop, Lars and Ehrenfried, Klaus (2005) Investigation of the unsteady flow field inside a leading edge slat cove. In: 11th AIAA/CEAS Aeroacoustics Conference, Conference proceedings, pp. 1-16. American Institute of Aeronautics and Astronautics. 11th AIAA/CEAS Aeroacoustics Conference, Monterey, California, USA, 23 -25 May 2005, 2005-05-23 - 2005-05-25, Monterey, CA (USA). ISBN 1-5634-7761-0.

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An experimental investigation of the unsteady flow field inside a slat cove was performed to identify possible sound source generation mechanisms. Tests were carried out on a swept constant chord half-model with a stored chord length of 0.45 m. Experiments were conducted in the 2.0 m x 1.4 m wind tunnel facility of the Technical University of Berlin at an angle of attack of 4°, 8°, 12° and 16° and free stream velocities ranging from 20 m/s up to 35 m/s. The slat cove flow field was investigated by Particle Image Velocimitry (PIV) while the radiated sound was recorded with a single microphone. Both measurements were conducted in a synchronized manner to allow a correlation between the flow field and the sound pressure. An inspection of instantaneous PIV images shows a free shear layer emanating from the slat cusp with discrete vortices further downstream. The shear layer impinges on the inner slat surface and some vortices get trapped inside the recirculation area. Based on a simplified form of the Lighthill-equation sound source terms are calculated. A dipole type sound source distribution is found along the shear layer with decreasing strength further down the shear layer. In addition the vortex shedding frequency of the shear layer vortices is estimated from the instantaneous PIV data. The shedding frequency has a Poisson-like probability distribution with center frequencies ranging from 4 kHz to 10 kHz. The mean shedding frequency scales linearly with the mean velocity of the shear layer. It could not clearly be verified that vortex shedding from the slat cusp is the cause for low frequency broad band noise. For a particular configuration several discrete tones can be observed. It is suspected that this tonal noise originates from the junction between the slat and the fuselage.

Item URL in elib:https://elib.dlr.de/18852/
Document Type:Conference or Workshop Item (Speech, Paper)
Additional Information: LIDO-Berichtsjahr=2005, monograph_id=AIAA 2005-2813,
Title:Investigation of the unsteady flow field inside a leading edge slat cove
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Journal or Publication Title:11th AIAA/CEAS Aeroacoustics Conference
Refereed publication:No
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Volume:Conference proceedings
Page Range:pp. 1-16
EditorsEmailEditor's ORCID iDORCID Put Code
Publisher:American Institute of Aeronautics and Astronautics
Series Name:CD-ROM
Keywords:PIV, Slat cove, noise source mechanisms, swept wing, airframe noise
Event Title:11th AIAA/CEAS Aeroacoustics Conference, Monterey, California, USA, 23 -25 May 2005
Event Location:Monterey, CA (USA)
Event Type:international Conference
Event Dates:2005-05-23 - 2005-05-25
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:Aircraft Research (old)
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Flight Physics (old)
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Helicopters
Institute of Aerodynamics and Flow Technology > Experimental Methods
Deposited By: Micknaus, Ilka
Deposited On:27 Jan 2006
Last Modified:14 Jan 2010 19:51

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