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Spectral Analysis of Velocity Fluctuations in the Vicinity of a Bias Flow Liner With Respect to the Damping Efficiency

Schulz, Anita and Haufe, Daniel and Czarske, Jürgen and Fischer, Andreas and Bake, Friedrich and Enghardt, Lars (2015) Spectral Analysis of Velocity Fluctuations in the Vicinity of a Bias Flow Liner With Respect to the Damping Efficiency. Acta acustica united with Acustica, 101 (1), pp. 24-36. Hirtzel. DOI: 10.3813/AAA.918801 ISSN 1610-1928

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Official URL: http://dx.doi.org/10.3813/AAA.918801

Abstract

Bias flow liners are perforated walls with an additional bias flow through the perforation. A common application is their integration in walls of hot gas areas, e.g. in combustion chambers of aero engines, for cooling. It is wellknown for a long time that the bias flow additionally provides a substantial amount of acoustic damping. However, until now the detailed damping mechanisms are not fully understood. Therefore, this study takes a closer look at the energy transfer from a propagating acoustic wave to the flow velocity field, which can be measured in the vicinity of the perforated wall. Two laser-optical measurement techniques, Doppler global velocimetry with sinusoidal laser frequency modulation (FM-DGV) and acoustic particle image velocimetry (A-PIV), were applied to a bias flow liner. The time-continuous velocity signal measured by FM-DGV was used to perform a spectral analysis of the fluctuating velocity components above the liner surface. This was done for different acousticexcitation frequencies, where the liner exhibits different dissipation rates. After removal of the acoustic Content from the power spectral density, the hydrodynamic velocity components feature a spectral augmentation in the vicinity of the excitation frequency. The effect appears downstream of the holes. The amount of spectral Augmentation correlates to the dissipation rate of the liner at the different excitation frequencies. Consequently, a certain transfer of acoustic energy into turbulent velocity fluctuations occurs in different frequency regimes. This energy transfer is, as a matter of fact, a function of the dissipation rate of the liner. Moreover, it has a strong dependence on the spatial location with respect to the orifice of the bias flow liner.

Item URL in elib:https://elib.dlr.de/95278/
Document Type:Article
Title:Spectral Analysis of Velocity Fluctuations in the Vicinity of a Bias Flow Liner With Respect to the Damping Efficiency
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Schulz, AnitaDLR, AT-TRAUNSPECIFIED
Haufe, DanielInstitut 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
Fischer, AndreasInstitut für Grundlagen der Elektrotechnik und Elektronik, Professur für Mess- und Prüftechnik, TU DresdenUNSPECIFIED
Bake, FriedrichDLR, AT-TRAUNSPECIFIED
Enghardt, LarsDLR, AT-TRAUNSPECIFIED
Date:January 2015
Journal or Publication Title:Acta acustica united with Acustica
Refereed publication:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:101
DOI :10.3813/AAA.918801
Page Range:pp. 24-36
Publisher:Hirtzel
ISSN:1610-1928
Status:Published
Keywords:Bias flow liner, laser optical measurement techniques, FM-DGV
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 - Combustion Chamber Technologies, L - Turbine Technologies, L - no assignment
Location: Berlin-Charlottenburg
Institutes and Institutions:Institute of Propulsion Technology > Engine Acoustic
Deposited By: Bake, Dr.-Ing. Friedrich
Deposited On:23 Feb 2015 08:26
Last Modified:10 Jan 2019 15:53

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