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Characterization of air terminal device noise using acoustic 1-port source models
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: 0000-0001-7898-8643
2007 (English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 300, no 05-mar, 727-743 p.Article in journal (Refereed) Published
Abstract [en]

A measurement method to characterize a standard air terminal device as an acoustic 1-port source has been tested and validated. The low-frequency noise generated by flow separation in the device and radiated to a reverberation room has been measured, together with pressure auto- and cross-spectra inside the connected duct. A 1-port source model with parameters derived from the in-duct data was then created. For the source strength part a scaling law was derived showing dipole dependence for the flow speed exponent. To validate the 1-port model and to prove its ability to predict flow noise generation, measurements were performed on a modified duct system.

Place, publisher, year, edition, pages
2007. Vol. 300, no 05-mar, 727-743 p.
Keyword [en]
sound, flow, ducts
National Category
Fluid Mechanics and Acoustics
URN: urn:nbn:se:kth:diva-16327DOI: 10.1016/j.jsv.2006.08.035ISI: 000243561200017ScopusID: 2-s2.0-33845886958OAI: diva2:334369
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2011-01-14Bibliographically approved
In thesis
1. Studies of flow duct acoustics with applications to turbocharged engines
Open this publication in new window or tab >>Studies of flow duct acoustics with applications to turbocharged engines
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A number of experimental and theoretical studies, performed in the field of technical flow duct acoustics are presented in this thesis. The acoustical methods treated are implemented on turbocharged IC-engines and engine gas exchange system components.

A new method based on the well-known two-load technique has been developed. The method was applied to characterise the source data of various piston-engines with non-linear behaviour including a 6 cylinder turbo-charged truck diesel engine. The source characterisation results were compared to the results obtained using the linear two-load technique. It was demonstrated that the new non-linear multi-load technique gives improved results when the source is slightly non-linear.

The use of active one-port models has been tested to characterize an air terminal device (ATD) as a source of flow generated noise. In order to predict the noise generation at different operating points of the device a scaling law was derived and verified. In the experimentally derived scaling law a flow speed dependence of 3 was found for the narrow band spectra, corresponding to a dipole-like behavior of the source in the plane wave range. The proposed technique was validated successfully and the results indicated a good prediction of in-duct sound generation by the air terminal device.

Sound reflection from hot flow duct openings has been investigated experimentally. The reflection coefficient was measured for flow temperatures up to 500 ºC and jet velocities up to 108m/s. The results have been compared with famous Munt’s theory. It was concluded that at low Mach number and Helmholz number cases the results agree well with the Munt’s model. This was the first experimental validation of the theory for hot flow conditions.

Experimental procedures to determine the sound transmission through automotive turbo-charger compressors were developed and described in detail. An overview of a unique turbocharger testing facility established at KTH CICERO in Stockholm is given. The facility can be used to measure acoustic two-port data for turbo-compressors. Results from measurements on a passenger car turbo-compressor are presented and the influence of operating conditions on the sound transmission is discussed. Current wave action models developed in CMT for computation of the gas exchange processes in I.C. engines have been implemented to determine the acoustic wave transmission through the turbo- compressor. The models are validated with the experimental data and the results are presented for different operating conditions of a Volvo passenger car turbo-compressor.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. 142 p.
Trita-AVE, ISSN 1651-7660 ; 2009:29
IC-engine, turbocharger, duct termination, flow duct, exhaust system, inlet system, acoustic source, one-port, two-port, source model, transmission loss, two-port matrix, reflection coefficient, source strength, multi-load method
National Category
Fluid Mechanics and Acoustics
urn:nbn:se:kth:diva-10590 (URN)
Public defence
2009-06-05, Sal D3, Lindstedtsvägen 5, KTH, Stockholm, 13:30 (English)
QC 20100809Available from: 2009-06-01 Created: 2009-05-29 Last updated: 2010-08-09Bibliographically approved

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Rämmal, HansÅbom, Mats
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