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Investigation of sound-flow interaction at a bias flow liner using 3D/3C velocity measurement and Helmholtz-Hodge decomposition

Gürtler, Johannes and Haufe, Daniel and Schulz, Anita and Bake, Friedrich and Enghardt, L. and Fischer, Andreas and Czarske, Jürgen (2016) Investigation of sound-flow interaction at a bias flow liner using 3D/3C velocity measurement and Helmholtz-Hodge decomposition. In: Proceedings 18th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics. 18th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics, JULY 4 – 7, 2016, Lisbon, Portugal.

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Abstract

In order to reduce the sound emission of modern gas turbines or jet engines, bias flow liners are used, where the damping of the sound is based on a complex interaction of the sound wave and the bias flow injected through a perforated facing sheet. The optimization of these liners regarding a high damping efficiency necessitates a deeper understanding of complex three dimensional (3D) aeroacoustic phenomena. To this aim, a contactless threecomponent vector (3C) measurement of both the flow velocity (in the order of several m/s) and the acoustic particle velocity (down to few mm/s) is needed. However, these two velocities overlap at the measured velocity, which necessitates the decomposition of the measured velocity field in order to analyze the interaction of sound and flow. For this purpose, the natural Helmholtz-Hodge decomposition is applied for the first time at a bias flow liner. Therefore, velocity field data is obtained with a high spatial resolution of 660 μm at more than 4000 measurement points using the frequency modulated Doppler global velocimeter. The measurement system provides a high dynamic range > 10³ and low uncertainty as well as a high measurement rate up to 100 kHz and, thus allows the measurement of both the flow field and the sound field. Furthermore, the analysis of the velocity spectrum is enabled. As a result, an oscillation of the fluid velocity is measured. This velocity oscillation is dominated by sound induced vortices in the flow. Additionally, the hypothesis of an aeroacoustic source near the facing sheet of the liner is suggested. As a perspective, the work provides new insights into aeroacoustic damping phenomena.

Item URL in elib:https://elib.dlr.de/113383/
Document Type:Conference or Workshop Item (Speech)
Title:Investigation of sound-flow interaction at a bias flow liner using 3D/3C velocity measurement and Helmholtz-Hodge decomposition
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Gürtler, Johannesinstitut für grundlagen der elektrotechnik und elektronik, professur für mess- und prüftechnik, tu dresdenUNSPECIFIED
Haufe, Danielinstitut für grundlagen der elektrotechnik und elektronik, professur für mess- und prüftechnik, tu dresdenUNSPECIFIED
Schulz, Anitadlr, at-traUNSPECIFIED
Bake, FriedrichFriedrich.Bake (at) dlr.dehttps://orcid.org/0000-0002-3235-428X
Enghardt, L.UNSPECIFIEDUNSPECIFIED
Fischer, Andreasinstitut für grundlagen der elektrotechnik und elektronik, professur für mess- und prüftechnik, tu dresdenUNSPECIFIED
Czarske, Jürgeninstitut für grundlagen der elektrotechnik und elektronik, professur für mess- und prüftechnik, tu dresdenUNSPECIFIED
Date:July 2016
Journal or Publication Title:Proceedings 18th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:aeroacoustics, noise damping, acoustic particle velocity, turbulent flows
Event Title:18th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics
Event Location:Lisbon, Portugal
Event Type:international Conference
Event Dates:JULY 4 – 7, 2016
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:propulsion systems
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Turbine Technologies
Location: Berlin-Charlottenburg
Institutes and Institutions:Institute of Propulsion Technology > Engine Acoustic
Deposited By: Bake, Dr.-Ing. Friedrich
Deposited On:21 Sep 2017 10:37
Last Modified:07 Feb 2018 16:22

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