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Acoustic characteristics of a heavy duty vehicle cooling module
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. Scania, Sweden.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.ORCID iD: 0000-0002-9061-4174
Scania AB, Sweden.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Vibration monitoring.ORCID iD: 0000-0001-7898-8643
2016 (English)In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 111, 67-76 p.Article in journal (Refereed) Published
Resource type
Text
Abstract [en]

Studies dedicated to the determination of acoustic characteristics of an automotive cooling package are presented. A shrouded subsonic axial fan is mounted in a wall separating an anechoic- and a reverberation room. This enables a unique separation of the up- and downstream sound fields. Microphone measurements were acquired of the radiated sound as a function of rotational speed, fan type and components included in the cooling module. The aim of the present work is to investigate the effect of a closely mounted radiator upstream of the impeller on the SPL spectral distribution. Upon examination of the SPL spectral shape, features linked specifically to the source and system are revealed. The properties of a reverberant sound field combined with the method of spectral decomposition permit an estimation of the source spectral distribution and the acoustic transfer response, respectively. Additionally, purely intrinsic acoustic properties of the radiator are scrutinized by standardized ISO methods. A new methodology comprising a dipole sound source is adopted to circumvent limitation of transmission loss measurement in the low frequency range. The sound attenuation caused by the radiator alone was found to be negligible.

Place, publisher, year, edition, pages
Elsevier, 2016. Vol. 111, 67-76 p.
Keyword [en]
Fan noise, Insertion loss, Installation effects, Spectral decomposition, Transmission loss, Acoustic field measurement, Acoustic fields, Acoustic properties, Acoustics, Architectural acoustics, Cooling, Fans, Insertion losses, Radiators, Reverberation, Wave transmission, Acoustic characteristic, Heavy duty vehicles, Reverberation rooms, Spectral distribution, Audio signal processing
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-186888DOI: 10.1016/j.apacoust.2016.04.004ISI: 000377837700008Scopus ID: 2-s2.0-84962788665OAI: oai:DiVA.org:kth-186888DiVA: diva2:930506
Note

QC 20160524

Available from: 2016-05-24 Created: 2016-05-16 Last updated: 2017-01-13Bibliographically approved
In thesis
1. An experimental and numerical study of an automotive cooling module
Open this publication in new window or tab >>An experimental and numerical study of an automotive cooling module
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Heavy vehicles are major emitters of noise. Especially at idle or low vehicle speeds a large portion of the noise emanates from the fan that forces the flow through the cooling module. The aim of this work is to investigate and reveal aerodynamic and acoustic installation effects linked to the cooling package. This introduces a multidisciplinary approach involving examination of the flow field, sound generation and sound propagation. The work includes two main parts: an experimental and a numerical part. The cooling module used throughout this work, named reduced cooling module, primarily includes a radiator, a shroud, a fan and a hydraulic engine to simplify the aeroacoustics analysis.

The experimental part comprises measurements of the sound emanated from the cooling package. A new approach to the spectral decomposition method is developed yielding the fan sound power or spectrum to be formulated as a product of a source part and a system part scaling with the Strouhal number and the Helmholtz number. Also, a separate determination of the transmission loss of the radiator is performed. The impact of the radiator on the transmitted noise was found to be negligible.

The numerical part incorporates comparisons from two aeroacoustics studies; a configuration where the fan is forced to operate at a fixed operation point and measured flow and turbulence statistics are available and the reduced cooling module. A hybrid turbulence modeling technique, IDDES, is adopted for the flow simulations. The sound propagation is calculated by the Ffowcs-Williams and Hawkings acoustic analogy when assuming a free-field sound propagation and by a finite element solver in the frequency domain to capture the installation effects. The simulated SPL conforms to the measured SPL and the blade response to the turbulent inflow and to the tip resolution, respectively, produce noise which spectral shape distribution is modified in accordance with earlier experimental findings published. Furthermore, the influence of an upstream radiator in close contact with the fan on the flow and sound fields is investigated. Here, the simulated aeroacoustic characteristics were found to change similarly to the acoustic measurements with and without radiator.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. 69 p.
Series
TRITA-AVE, ISSN 1651-7660 ; 2017:01
Keyword
Fan installation effects, spectral decomposition, aeroacoustics
National Category
Fluid Mechanics and Acoustics
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-199285 (URN)978-91-7729-195-4 (ISBN)
Public defence
2017-01-27, D2, Lindstedtsvägen 5, Stockholm, 10:00 (English)
Opponent
Supervisors
Available from: 2017-01-03 Created: 2017-01-03 Last updated: 2017-01-03Bibliographically approved

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