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About the ambiguity of noise source localization based on the causality correlation technique

Henning, Arne and Wrede, Björn and Schröder, Andreas (2014) About the ambiguity of noise source localization based on the causality correlation technique. 17th Internatinal Symposium on Application Laser Techniques to Fluid Mechanics, 07. - 10. July 2014, Lisbon, Portugal.

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Official URL: http://ltces.dem.ist.utl.pt/lxlaser/lxlaser2014/program.asp

Abstract

Samples of typical causality correlation results for synchronized PIV and acoustic measurements on a rod-airfoil configuration and a cold jet are presented. The difficulties in interpreting the resulting correlation coefficients between turbulent ow quantities and the far-field pressure fluctuations are illustrated. An approach for the interpretation of the space time resolved coefficient matrix is demonstrated, with special attention to the influence of coherent structures in the flow topology. Two simplified models of the coherent structures in subsonic jets are analysed in order to contribute to the understanding and a meaningful interpretation of causality correlation results. The first model is simulating a distribution of correlated monopoles on the axis of a jet. The second is based on a jittering wave-packet along the jet-axis. The radiated sound from these modelled sources is calculated and correlated with the source signal. The dependency of the resulting coefficient matrix on the temporal and spatial extend of the source distribution is studied. Truncation effects and the influences of the temporally localized changes in the wave-packet are investigated. It can be shown that resulting high amplitude bursts in the far-field pressure are dominating the space-time evolution of the correlation coefficient. Supported by a comparison of recently obtained measurement results for a subsonic jet generated by a chevron nozzle and a round nozzle, it can be shown that the obtained coefficient matrix indeed provides space time resolved information about flow regions which are subject to the same physical phenomenon as the aeroacoustic source.

Item URL in elib:https://elib.dlr.de/89795/
Document Type:Conference or Workshop Item (Speech)
Additional Information:Paper-Nr.: 02.3_3_319
Title:About the ambiguity of noise source localization based on the causality correlation technique
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Henning, Arnearne.henning (at) dlr.deUNSPECIFIED
Wrede, Björnbjoern.wrede (at) dlr.deUNSPECIFIED
Schröder, Andreasandreas.schroeder (at) dlr.deUNSPECIFIED
Date:2014
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Page Range:pp. 1-11
Series Name:Conference Proceedings online
Status:Published
Keywords:Aeroacoustics, PIV, Causality-Correlation, Jet-Noise
Event Title:17th Internatinal Symposium on Application Laser Techniques to Fluid Mechanics
Event Location:Lisbon, Portugal
Event Type:international Conference
Event Dates:07. - 10. July 2014
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Transport
HGF - Program Themes:Terrestrial Vehicles (old)
DLR - Research area:Transport
DLR - Program:V BF - Bodengebundene Fahrzeuge
DLR - Research theme (Project):V - Next Generation Train III (old)
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Fluid Systems
Institute of Aerodynamics and Flow Technology > Experimental Methods
Deposited By: Micknaus, Ilka
Deposited On:21 Jul 2014 17:14
Last Modified:20 Oct 2014 14:21

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