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Piggyback: What we can learn about the Turbulent Boundary Layer from closed Test Section Acoustic Array Measurements

Haxter, Stefan and Spehr, Carsten (2019) Piggyback: What we can learn about the Turbulent Boundary Layer from closed Test Section Acoustic Array Measurements. In: Flinovia III - Flow Induced Noise and Vibration Issues and Aspects, 1 - 2. Flinovia III - Flow Induced Noise and Vibration Issues and Aspects, 2.-4. Sept. 2019, Lyon, France.

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Official URL: https://flinovia3.sciencesconf.org/data/program/Haxter_1.pdf

Abstract

A large number of aeroacoustic wind tunnel measurements is performed in research facilities around the world aiming at locating noise sources on scaled models. In the following, the focus is however not set on the issue of locating noise sources on the research model, but rather to utilize a bybroduct of such measurements in closed test sections: the hydrodynamic pressure fluctuations from the turbulent boundary layer. In the majority of acoustic measurements, a phased array is being used to locate the sources on the research model. Such arrays consist of hundreds of microphones that are placed at carefully chosen locations either outside the flow in open test section wind tunnels, or underneath the turbulent boundary layer in closed test section wind tunnels. In the latter case, the pressure fluctuations recorded by the microphones are of both, hydrodynamic and of acoustic nature. In acoustic beamforming analysis, oftentimes the hydrodynamic pressure fluctuations are regarded as noise which mostly affects the main diagonal elements of the cross-spectral matrix. Therefore, the diagonal elements are commonly set to zero in order to avoid the effects of this noise on the beamforming map. In the following analysis, it is this "noise" that the focus will be set on. Analysis of the turbulent boundary layer pressure fluctuations can be used to both, learn about its characteristics, and to design better arrays for future measurements. A successful methodology for this "noise" evaluation will open up new possibilities of evaluating existing measurements for the the characterization of turbulent boundary layer pressure fluctuations.

Item URL in elib:https://elib.dlr.de/129777/
Document Type:Conference or Workshop Item (Speech)
Additional Information:Full length papers to be included in the published book will be requested after the symposium. https://flinovia3.sciencesconf.org/
Title:Piggyback: What we can learn about the Turbulent Boundary Layer from closed Test Section Acoustic Array Measurements
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Haxter, Stefanstefan.haxter (at) dlr.dehttps://orcid.org/0000-0002-9232-2802
Spehr, Carstencarsten.spehr (at) dlr.dehttps://orcid.org/0000-0002-2744-3675
Date:September 2019
Journal or Publication Title:Flinovia III - Flow Induced Noise and Vibration Issues and Aspects
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Page Range:1 - 2
Series Name:Conference Proceedings online
Status:Published
Keywords:Wind tunnel meaurements, Turbulent Boundary Layer, Microphone Array
Event Title:Flinovia III - Flow Induced Noise and Vibration Issues and Aspects
Event Location:Lyon, France
Event Type:international Conference
Event Dates:2.-4. Sept. 2019
Institution:Deutsches Zentrum für Luft- und Raumfahrt e.V.
Department:AS-EXV
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Simulation and Validation
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Experimental Methods, GO
Deposited By: Micknaus, Ilka
Deposited On:23 Oct 2019 16:08
Last Modified:23 Oct 2019 16:08

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