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 effect of grazing-bias flow on the self sustained oscillations in a side branch
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
2010 (English)In: 20th International Congress on Acoustics 2010, ICA 2010 - Incorporating Proceedings of the 2010 Annual Conference of the Australian Acoustical Society, 2010, 176-181 p.Conference paper, Published paper (Refereed)
Abstract [en]

The flow-acoustic interaction in a T-junction can result in both amplification and attenuation of incoming waves. The frequency ranges of amplification are mainly governed by the time scales of convection of hydrodynamic instabilities over the side branch opening. With bias flow, i.e. flow through the side branch the amplification can increase or completely vanish. In this paper this effect is studied for a T-junction of rectangular ducts, with a grazing Mach number of 0.1 and a varying bias inflow. When the bias inflow Mach number changes from 0 to 0.01 the amplification is increased severely. Further increasing the bias inflow has the effect of lower the amplification again towards zero at a bias Mach number of 0.05.

Place, publisher, year, edition, pages
2010. 176-181 p.
Keyword [en]
Flow-acoustic interaction, Flowthrough, Frequency ranges, Hydrodynamic instabilities, Inflow Mach number, Rectangular ducts, Self-sustained oscillations, Side branches, T junctions, Time-scales
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-26141Scopus ID: 2-s2.0-84869137211ISBN: 978-161782745-7 (print)OAI: oai:DiVA.org:kth-26141DiVA: diva2:370445
Conference
20th International Congress on Acoustics 2010, ICA 2010 - Incorporating the 2010 Annual Conference of the Australian Acoustical Society; Sydney, NSW; Australia; 23 August 2010 through 27 August 2010
Funder
Swedish Research Council
Note

QC 20101118

Available from: 2010-11-16 Created: 2010-11-16 Last updated: 2014-08-15Bibliographically 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

Scopus

Search in DiVA

By author/editor
Holmberg, AndreasKarlsson, Mikael
By organisation
Marcus Wallenberg Laboratory MWLLinné Flow Center, FLOW
Fluid Mechanics and Acoustics

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 42 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