Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
The Error Suppression of an Experimental Over-Determination of In-Duct Flow Noise Sources
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.ORCID iD: 0000-0002-8474-8563
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.ORCID iD: 0000-0001-7898-8643
2010 (English)In: 16th AIAA/CEAS Aeroacoustics Conference, Stockholm, June 2010, 2010, 1-19 p.Conference paper, Published paper (Refereed)
Abstract [en]

The full aeroacoustic two-port measurement procedure in flow ducts involves the determination of a scattering matrix and a source term. In this paper, the improved error suppression of a recently developed over-determination technique for the source is investigated. By inducing disturbances in the reflection coefficients it is shown that by applying the over-determination the accuracy is improved. For errors introduced via the scattering matrix the results are identical regardless of method applied. From measurements it is shown that random errors in the microphone data are better suppressed using the over-determination method. While this is true for bias errors due to external sound sources as well, the accuracy is unsatisfying when the external source generated sound is more than about 3 dB louder than that of the two-port source.

Place, publisher, year, edition, pages
2010. 1-19 p.
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-26140Scopus ID: 2-s2.0-78649590915OAI: oai:DiVA.org:kth-26140DiVA: diva2:370443
Conference
16th AIAA/CEAS Aeroacoustics Conference
Funder
Swedish Research Council
Note

QC 20101118

Available from: 2010-11-16 Created: 2010-11-16 Last updated: 2016-06-08Bibliographically approved
In thesis
1. Experimental Determination of Aeracoustic Sources in Low Mach Number Internal Flows
Open this publication in new window or tab >>Experimental Determination of Aeracoustic Sources in Low Mach Number Internal Flows
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, the in-duct experimental methods for determining aeroacoustic N-ports of in-duct elements are discussed and improved. The scattering matrix determination methods and the related wave decomposition methods are evaluated from measurements in an empty duct carrying a mean flow. The improvements of a new over-determination method for the source part of the N-port is studied using simulations and measurements; in quiescent air as well as measurements of the flow associated noise of a mixer plate, here a triangular plate inserted at an angle in a duct. The new method is shown to improve suppression of random errors while no improvement is achieved for bias errors.

 

Further, the methods are applied in the study of two different aeroacoustic phenomena; one is the effect on the flow associated noise of the triangular plate achieved by varying the bending stiffness. For the most resilient plate tested, it is observed that when the Strouhal number of the flow noise coalesce with the Helmholtz number of a specific eigen-mode of the plate, the noise is drastically dampened. There is also a weaker broad band effect.

 

The other phenomena studied is the amplification and attenuation obtained for sound waves propagating in a T-junction of rectangular ducts. It is found that by adding only 10% of inflow in the side branch relative to that in the main branch, the amplification is heavily increased. By adding another 10% the amplification is again similar to that of no side branch flow. Adding further flow lessens the effects still.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010
Series
Trita-AVE, ISSN 1651-7660 ; 2010:69
Keyword
Aeracoustics, ducts, N-ports, scattering matrix, wave decomposition, source determination, over-determination, flow noise, fluid-acoustic interaction, fluid-structure-acoustic interaction, wave number, T-junction, power balance, grazing-bias flow
National Category
Fluid Mechanics and Acoustics Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-26133 (URN)
Presentation
2010-12-09, MWL 74, Teknikringen 8, Stockholm, KTH, 13:00 (English)
Opponent
Supervisors
Projects
Experimental characterization of aero-acoustic sources
Funder
Swedish Research Council
Note
QC 20101118Available from: 2010-11-18 Created: 2010-11-16 Last updated: 2010-11-18Bibliographically approved

Open Access in DiVA

No full text

Other links

ScopusPublished version

Authority records BETA

Bodén, HansÅbom, Mats

Search in DiVA

By author/editor
Holmberg, AndreasBodén, HansÅbom, Mats
By organisation
Marcus Wallenberg Laboratory MWL
Fluid Mechanics and Acoustics

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 62 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf