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Microphone-Array Measurements of a Model Scale Contra-Rotating Open Rotor in a Reverberant Open Wind-Tunnel

Funke, St. and Kim, L. and Siller, H. (2011) Microphone-Array Measurements of a Model Scale Contra-Rotating Open Rotor in a Reverberant Open Wind-Tunnel. In: Proceedings 17th AIAA / CEAS Aeroacoustics Conference (32nd Aeroacoustics Conference). AIAA. 17th AIAA / CEAS Aeroacoustics Conference (32nd AIAA Aeroacoustics Conference), 05.06. - 08.06.2011, Portland, USA.

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Abstract

The DLR department of engine acoustics performed acoustic measurements of a contra-rotating open-rotor (CROR) model with a linear microphone array in the T-104 open wind-tunnel at TsAGI. The microphone data is corrected for shear-layer effects using the model of an infinitely thin shear layer by Amiet. Investigations of the room-acoustics of the test hall show strong reflections from the ceiling and two side walls, which cause strong interference patterns at the microphone positions. The acoustic change between different rotor confgurations, like different rotor spacings and an upstream mounted mock pylon, is shown with spatially averaged spectra. The evaluation of the source directivities is strongly influenced by the interference patterns of the reflections in the test hall. The rotor tones can be localized at the correct position with classical beamforming. The inverse method SODIX is used to model the directivities of the broadband sound-sources of the CROR. Green's functions that take the shear layer and the first-order reflections into account were implemented. The accuracy of these correction methods could be investigated with the directive SODIX results. The shear-layer model gives accurate results for emission angles < 100° while all modeled sources move downstream for larger emission angles. Corrections for the first-order reflections of the test hall show an increased spatial resolution of the SODIX results and a suppression of artificial sources.

Document Type:Conference or Workshop Item (Paper)
Title:Microphone-Array Measurements of a Model Scale Contra-Rotating Open Rotor in a Reverberant Open Wind-Tunnel
Authors:
AuthorsInstitution or Email of Authors
Funke, St.UNSPECIFIED
Kim, L.UNSPECIFIED
Siller, H.UNSPECIFIED
Date:2011
Journal or Publication Title:Proceedings 17th AIAA / CEAS Aeroacoustics Conference (32nd Aeroacoustics Conference)
Refereed publication:Yes
In ISI Web of Science:No
Publisher:AIAA
Status:Published
Keywords:Mikrofonarray, Windkanal, Offene gegenläufige Rotoren, Schallquellenlokalisierung, SODIX, Beamforming, Scherschicht, Reflexion, Microphone-Array, Wind-Tunnel, CROR, Contra-Rotating Open Rotor, Source Localization, Shear Layer, Reverberation
Event Title:17th AIAA / CEAS Aeroacoustics Conference (32nd AIAA Aeroacoustics Conference)
Event Location:Portland, USA
Event Type:international Conference
Event Dates:05.06. - 08.06.2011
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-Adlershof
Institutes and Institutions:Institute of Propulsion Technology > Engine Acoustic
Deposited By: Balbir Kaur
Deposited On:20 Jan 2012 14:53
Last Modified:09 Feb 2012 15:46

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