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Publications (10 of 151) Show all publications
Rynell, A., Chevalier, M., Åbom, M. & Efraimsson, G. (2018). A numerical study of noise characteristics originating from a shrouded subsonic automotive fan. Applied Acoustics, 140, 110-121
Open this publication in new window or tab >>A numerical study of noise characteristics originating from a shrouded subsonic automotive fan
2018 (English)In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 140, p. 110-121Article in journal (Refereed) Published
Abstract [en]

The characteristics of the noise radiated from a reduced automotive cooling module are numerically studied focusing on the interaction effects linked to the sound generation mechanisms and the acoustic scattering caused by the confined installation. The flow field is simulated by adopting the formulation of Improved Delayed Detached Eddy Simulation (IDDES), which is a numerical technique that enables large-scale structures to be resolved and the wall-bounded flow to be treated depending on the turbulent content within the boundary layer. By comparing the simulated fan performance to two sets of measurement data of a similar setup, the aerodynamic results obtained from IDDES are validated and conformed to the volumetric flow rate delivered for the pressure drop measured. The acoustic part of the study comprises evaluation of the sound source associated with the momentum distribution imposed on the surroundings at an interface slightly upstream of the fan. At the microphone positions upstream of the installation, the SPL falls within the SPL range measured and the acoustic power delivered by the fan conforms to the SWL obtained from the comparison method in the reverberation room. The system response function, estimated by subtracting the SWL for the free-field simulation from the SWL associated with the reduced automotive cooling module marks spectral humps at fixed frequencies, irrespectively of sound source. As such, the engineering approach to the spectral decomposition method earlier published, which enables the acoustical properties of the installation to be isolated from the source, is validated and found to hold.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Aeroacoustics, Fan noise, IDDES, Installation effects, Spectral decomposition
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-228690 (URN)10.1016/j.apacoust.2018.05.006 (DOI)000440121900012 ()2-s2.0-85047243465 (Scopus ID)
Note

QC 20180529

Available from: 2018-05-29 Created: 2018-05-29 Last updated: 2018-08-20Bibliographically approved
Vizzini, S., Knutsson, M., Dybeck, M. & Åbom, M. (2018). Flow Noise Generation in a Pipe Bend. Paper presented at SAE 10th International Styrian Noise, Vibration and Harshness Congress: The European Automotive Noise Conference, SNVH 2018, Congress Graz Sparkassenplatz 1Graz, Austria, 20 June 2018 through 22 June 2018. SAE technical paper series, 2018-June(June)
Open this publication in new window or tab >>Flow Noise Generation in a Pipe Bend
2018 (English)In: SAE technical paper series, ISSN 0148-7191, Vol. 2018-June, no JuneArticle in journal (Refereed) Published
Abstract [en]

Noise generated by low Mach number flow in duct networks is important in many industrial applications. In the automotive industry the two most important are the ventilation duct network and the engine exhaust system. Traditionally, design is made based on rule-of thumb or slightly better by simple semi-empirical scaling laws for flow noise. In many cases, strong curvatures and local deviations from circular cross-sections are created due to outer geometry restrictions. This can result in local relatively high flow velocities and complex flow separation patterns and as a result, rule-of thumb and scaling law methods can become highly inaccurate and uncertain. More advanced techniques based on time domain modelling of the fluid dynamics equations together with acoustic analogies can offer a better understanding of the local noise generation, the propagation and interaction with the rest of the system. This investigation focuses on validating an SNGR numerical model to predict flow noise generation due to separation in a circular duct with a 90-degree bend carrying a flow lower than 0.3 Mach number. Experimental results are presented and compared to numerical simulations, based on a combination of steady computational fluid dynamics and the stochastic acoustic analogy by Lighthill, as well as semi-empirical models based two-ports.

Place, publisher, year, edition, pages
SAE International, 2018
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-233711 (URN)10.4271/2018-01-1525 (DOI)2-s2.0-85050533001 (Scopus ID)
Conference
SAE 10th International Styrian Noise, Vibration and Harshness Congress: The European Automotive Noise Conference, SNVH 2018, Congress Graz Sparkassenplatz 1Graz, Austria, 20 June 2018 through 22 June 2018
Note

QC 20180831

Available from: 2018-08-31 Created: 2018-08-31 Last updated: 2018-08-31Bibliographically approved
Kabral, R. & Åbom, M. (2018). Investigation of turbocharger compressor surge inception by means of an acoustic two-port model. Journal of Sound and Vibration, 412, 270-286
Open this publication in new window or tab >>Investigation of turbocharger compressor surge inception by means of an acoustic two-port model
2018 (English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 412, p. 270-286Article in journal (Refereed) Published
Abstract [en]

The use of centrifugal compressors have increased tremendously in the last decade being implemented in the modern IC engine design as a key component. However, an efficient implementation is restricted by the compression system surge phenomenon. The focus in the investigation of surge inception have mainly been on the aerodynamic field while neglecting the acoustic field. In the present work a new method based on the full acoustic 2-port model is proposed for investigation of centrifugal compressor stall and surge inception. Essentially, the compressor is acoustically decoupled from the compression system, hence enabling the determination of sound generation and the quantification of internal aero-acoustic coupling effects, both independently of the connected pipe system. These frequency dependent quantities are indicating if the compressor is prone to self-sustained oscillations in case of positive feedback when installed in a system. The method is demonstrated on experimentally determined 2-port data of an automotive turbocharger centrifugal compressor under a variety of realistic operating conditions.

Place, publisher, year, edition, pages
Academic Press, 2018
Keywords
Centrifugal compressor acoustics, Surge inception, Stall, Sound generation, Noise, Full 2-port
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-219483 (URN)10.1016/j.jsv.2017.10.003 (DOI)000416040400016 ()2-s2.0-85034217168 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme, 289352
Note

QC 20171207

Available from: 2017-12-07 Created: 2017-12-07 Last updated: 2017-12-07Bibliographically approved
Nashed, M. W., Elnady, T. & Åbom, M. (2018). Modeling of duct acoustics in the high frequency range using two-ports. Applied Acoustics, 135, 37-47
Open this publication in new window or tab >>Modeling of duct acoustics in the high frequency range using two-ports
2018 (English)In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 135, p. 37-47Article in journal (Refereed) Published
Abstract [en]

Design of duct networks is challenging because the design should consider the required flow rate, acceptable noise levels, and minimum pressure drop to achieve optimum performance. This paper presents acoustic analysis in high frequency range using sound power two-ports applied to Heating, Ventilation, and Air Conditioning (HVAC) systems. To simulate the acoustic behaviour one need to model three mechanisms; the sound power generated from sound sources (e.g. Fans), the regenerated sound power caused by the flow in different elements in the network (e.g. junctions), and the sound power loss across different elements of the network. The general approach considered here is based on two-port theory that divides the duct network into two-port elements. Each element can be described by 2 x 2 scattering matrix where the state variables are the acoustic power flow in both up and downstream directions. Junctions and branching are described by multi-port elements depending on the number of elements connected to this multiport. This algorithm is compared to measurements of HVAC system located in an academic building that shows good agreement. An advantage of this approach is the ability to use the same formalism of the two-port network theory to analyse the acoustic behaviour in both low and high frequency ranges beside the flow distribution and the pressure drop.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2018
Keywords
Acoustics, Two-port, Sound power, HVAC, High frequency
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-226181 (URN)10.1016/j.apacoust.2018.01.009 (DOI)000428484500005 ()2-s2.0-85041459373 (Scopus ID)
Note

QC 20180516

Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2018-05-16Bibliographically approved
Spillere, A. M., Zhang, Z., Cordioli, J. A., Åbom, M. & Bodén, H. (2018). Optimum impedance in the presence of an inviscid sheared flow. In: 2018 AIAA/CEAS Aeroacoustics Conference: . Paper presented at AIAA/CEAS Aeroacoustics Conference, 2018, Atlanta, United States, 25 June 2018 through 29 June 2018. American Institute of Aeronautics and Astronautics, Article ID AIAA 2018-3777.
Open this publication in new window or tab >>Optimum impedance in the presence of an inviscid sheared flow
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2018 (English)In: 2018 AIAA/CEAS Aeroacoustics Conference, American Institute of Aeronautics and Astronautics, 2018, article id AIAA 2018-3777Conference paper, Published paper (Refereed)
Abstract [en]

In recent years, much effort has been devoted to find the “optimum impedance” i.e. the impedance that results in the maximum modal decay rate in flow duct acoustics. Although such analysis can be carried out by means of numerical simulations, analytical expressions can also be derived in order to predict the optimum impedance. Previous works have been concerned over the optimum impedance of higher order modes in rectangular ducts with uniform flow. In this work, the analysis is expanded to circular and rectangular ducts for both uniform and sheared inviscid flows. Focus is given on a typical aero-engine intake and flight conditions. It is shown that, in certain conditions, the optimum impedance is affected even by the presence of a small boundary layer thickness. It is also noted that for low Helmholtz numbers the optimum impedance may have a negative resistance.

Place, publisher, year, edition, pages
American Institute of Aeronautics and Astronautics, 2018
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-233739 (URN)10.2514/6.2018-3777 (DOI)2-s2.0-85051301729 (Scopus ID)9781624105609 (ISBN)
Conference
AIAA/CEAS Aeroacoustics Conference, 2018, Atlanta, United States, 25 June 2018 through 29 June 2018
Note

QC 20180831

Available from: 2018-08-31 Created: 2018-08-31 Last updated: 2018-08-31Bibliographically approved
Williams, P., Kirby, R., Hill, J., Åbom, M. & Malecki, C. (2018). Reducing low frequency tonal noise in large ducts using a hybrid reactive-dissipative silencer. Applied Acoustics, 131, 61-69
Open this publication in new window or tab >>Reducing low frequency tonal noise in large ducts using a hybrid reactive-dissipative silencer
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2018 (English)In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 131, p. 61-69Article in journal (Refereed) Published
Abstract [en]

Noise generated by fans or turbines normally consists of a combination of narrow and broadband noise. To lower transmitted noise levels, it is attractive to use a combination of reactive and dissipative elements. However, this approach presents a number of challenges for larger systems. This is because reactive elements are commonly placed around the duct circumference where they are normally only effective up to the frequency at which the first higher order mode cuts on in the duct. For larger systems, this means that reactive elements work only in the low, and often very low, frequency range, whereas dissipative elements, which are distributed across the duct cross-section, generally work well in the medium to high frequency range. This can cause noise problems in the low to medium frequency range in larger systems. This article presents an alternative approach for delivering noise attenuation over the low to medium frequency range that is suitable for application in larger duct systems. This approach takes advantage of those splitter silencer designs commonly used in larger systems to integrate a reactive element into the splitter design. This delivers a hybrid splitter that uses a combination of dissipative and reactive elements so that the reactive element partitions the main airway. This has the advantage of introducing a quasi-planar transverse sound pressure field for each resonator in the low to medium frequency range, including frequencies above the first cut-on. It is demonstrated using predictions and measurements taken for a number of example silencers, that this approach enables reactive elements to work over an extended low to medium frequency range, including at frequencies above the first cut-on mode in the main duct. Accordingly, it is shown that a hybrid dissipative-reactive splitter design is capable of delivering improved levels of attenuation in the crucial low to medium frequency range.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Hybrid silencer, Large ducts, Low frequency noise
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-218921 (URN)10.1016/j.apacoust.2017.10.018 (DOI)2-s2.0-85032878775 (Scopus ID)
Note

QC 20171201

Available from: 2017-12-01 Created: 2017-12-01 Last updated: 2017-12-01Bibliographically approved
Kim, D.-Y. -., Ih, J.-G. -., Zhang, Z. & Åbom, M. (2017). A virtual herschel-quincke tube using slow sound. In: INTER-NOISE 2017 - 46th International Congress and Exposition on Noise Control Engineering: Taming Noise and Moving Quiet. Paper presented at 46th International Congress and Exposition on Noise Control Engineering: Taming Noise and Moving Quiet, INTER-NOISE 2017, 27 August 2017 through 30 August 2017. Institute of Noise Control Engineering
Open this publication in new window or tab >>A virtual herschel-quincke tube using slow sound
2017 (English)In: INTER-NOISE 2017 - 46th International Congress and Exposition on Noise Control Engineering: Taming Noise and Moving Quiet, Institute of Noise Control Engineering , 2017Conference paper, Published paper (Refereed)
Abstract [en]

While an acoustic wave propagates along a duct, of which the wall is treated with either dissipative or a reactive material, the phase speed can be slowed down because of wave dispersion. It has been thought that such slow sound can be used for a novel control method to reduce the in-duct noise at low to medium frequencies generated from a fluid machinery system. In this work, the Herschel-Quincke tube (hereafter, H-Q tube), which exploits the path length difference of two parallel ducts, is modified to demonstrate the application potential of the slow sound. A test rig is designed to create the two different phase speeds by arranging the two parallel, equal-length ducts inside a main duct, one of them is hard-walled and the other one lined with a periodic array of resonators. This slow sound H-Q device is then modelled by both analytical and numerical methods assuming a plane wave incidence. Also, an experiment is conducted to measure the transmission loss. The result reveals a low frequency peak (TL-30 dB) in the range of 200-400 Hz, which occurs far below the lowest resonance of the resonator. At the original resonance frequency of 691 Hz, a small attenuation (TL~6 dB) is obtained due to the fact that one duct is subject to a high loss, and the other is without appreciable loss. The result clearly demonstrates the potential of applying slow sound device to overcome the spatial limitation of the classical H-Q tube.

Place, publisher, year, edition, pages
Institute of Noise Control Engineering, 2017
Keywords
Acoustic metamaterial, Herschel-quincke tube, Parallel ducts, Slow sound, Transmission loss
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-224422 (URN)2-s2.0-85042121454 (Scopus ID)
Conference
46th International Congress and Exposition on Noise Control Engineering: Taming Noise and Moving Quiet, INTER-NOISE 2017, 27 August 2017 through 30 August 2017
Note

QC 20180319

Available from: 2018-03-19 Created: 2018-03-19 Last updated: 2018-03-19Bibliographically approved
Kabral, R., El Nemr, Y., Ludwig, C., Mirlach, R., Koutsovasilis, P., Masrane, A. & Åbom, M. (2017). Experimental acoustic characterization of automotive twin-scroll turbine. In: 12th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics, ETC 2017: . Paper presented at 12th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics, ETC 2017, Quality Hotel Globe, Stockholm, Sweden, 3 April 2017 through 7 April 2017. KTH Royal Institute of Technology
Open this publication in new window or tab >>Experimental acoustic characterization of automotive twin-scroll turbine
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2017 (English)In: 12th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics, ETC 2017, KTH Royal Institute of Technology, 2017Conference paper, Published paper (Other academic)
Abstract [en]

The present paper focuses on the experimental determination of automotive twin-scroll turbine acoustic performance. The unique test-rig for automotive turbocharger acoustics at KTH CCGEx laboratory is further developed to enable testing of modern twin-scroll turbines under controlled laboratory conditions. It is shown how the passive acoustic properties of such turbines can be accurately characterized by means of an acoustic three-port formulation. Governing equations along with the new test-rig design are presented and discussed in detail. Furthermore, complementary results from the first experimental determination of twin-scroll turbine acoustic three-port data are presented.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2017
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-207150 (URN)2-s2.0-85021810533 (Scopus ID)
Conference
12th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics, ETC 2017, Quality Hotel Globe, Stockholm, Sweden, 3 April 2017 through 7 April 2017
Note

QC 20170522

Available from: 2017-05-17 Created: 2017-05-17 Last updated: 2017-08-16Bibliographically approved
Zhang, Z., Åbom, M., Bodén, H., Karlsson, M. & Katoshevski, D. (2017). Particle Number Reduction in Automotive Exhausts Using Acoustic Metamaterials. SAE International Journal of Engines, 10(4), 1566-1572
Open this publication in new window or tab >>Particle Number Reduction in Automotive Exhausts Using Acoustic Metamaterials
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2017 (English)In: SAE International Journal of Engines, ISSN 1946-3936, E-ISSN 1946-3944, Vol. 10, no 4, p. 1566-1572Article in journal (Refereed) Published
Abstract [en]

Air pollution caused by exhaust particulate matter (PM) from vehicular traffic is a major health issue. Increasingly strict regulations of vehicle emission have been introduced and efforts have been put on both the suppression of particulate formation inside the engine cylinders and the development of after-treatment technologies such as filters. With modern direct injected engines that produce a large number of really small sub-micron particles, the focus has increased even further and now also includes a number count.The problem of calculating particle trajectories in flow ducts like vehicle exhaust systems is challenging but important to further improve the technology. The interaction between particles and oscillating flows may lead to the formation of particle groups (regions where the particle concentration is increased), yielding a possibility of realizing particle agglomeration. The oscillating flow may simply be hydrodynamic or as assumed here: the flow oscillations are created by sound propagation rather than hydrodynamic approaches. An analysis is presented which gives the relationship between the speed of sound, the mean flow velocity and the amplitude of the acoustic particle velocity for particle agglomeration to be feasible. It is shown that it can be achieved if the convective speed of sound is reduced to the same order as the mean flow velocity. It is therefore suggested to use the so-called acoustic metamaterials, which can help control, direct and manipulate sound waves. At this stage a phenomenological 1D model is used for the analysis, which allows the authors to build an understanding of the effect of the sound waves and flow oscillations on particle motion and paves the way for further analysis on particle agglomeration.

Place, publisher, year, edition, pages
SAE International, 2017
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-216542 (URN)10.4271/2017-01-0909 (DOI)000416807900016 ()2-s2.0-85018319516 (Scopus ID)
Note

QC 20171124

Available from: 2017-11-24 Created: 2017-11-24 Last updated: 2018-01-03Bibliographically approved
Rynell, A., Efraimsson, G., Chevalier, M. & Åbom, M. (2016). Acoustic characteristics of a heavy duty vehicle cooling module. Applied Acoustics, 111, 67-76
Open this publication in new window or tab >>Acoustic characteristics of a heavy duty vehicle cooling module
2016 (English)In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 111, p. 67-76Article in journal (Refereed) Published
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
Keywords
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:nbn:se:kth:diva-186888 (URN)10.1016/j.apacoust.2016.04.004 (DOI)000377837700008 ()2-s2.0-84962788665 (Scopus ID)
Note

QC 20160524

Available from: 2016-05-24 Created: 2016-05-16 Last updated: 2017-11-30Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-7898-8643

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