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Acoustic Source Characterization for Prediction of Medium Speed Diesel Engine Exhaust Noise
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).ORCID iD: 0000-0001-7898-8643
2014 (English)In: Journal of Vibration and Acoustics-Transactions of the ASME, ISSN 1048-9002, Vol. 136, no 2, 021008- p.Article in journal (Refereed) Published
Abstract [en]

To achieve reliable results when simulating the acoustics of the internal combustion engine (IC-engine) exhaust system and its components, the source characteristics of the engine must be known. In the low frequency range only plane waves propagate and then one-port source data can be determined using, for example, the acoustic multiload method. For the medium speed IC-engines used in power plants and ships, the exhaust duct noise often needs to be analyzed up to 10 kHz, i.e., far beyond the plane wave range, and it is then more appropriate to use acoustic power to characterize the source. This power should ideally be measured under reflection-free conditions in the exhaust duct. The results from an earlier study showed that a suitable way to characterize the source for any frequency is to determine the in-duct sound power by extending the plane wave formulation with frequency band power weighting factors. The aim of this study is to apply this high frequency range method in situ to a real test engine. Another aim is to define, theoretically, how to combine the source data in the low frequency plane wave range with those in the high frequency nonplane wave range using a source sound power formulation.

Place, publisher, year, edition, pages
2014. Vol. 136, no 2, 021008- p.
Keyword [en]
Duct, System
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-143972DOI: 10.1115/1.4026138ISI: 000332223800008ScopusID: 2-s2.0-84903739891OAI: diva2:710470

QC 20140407

Available from: 2014-04-07 Created: 2014-04-04 Last updated: 2015-11-19Bibliographically approved
In thesis
1. Acoustic In-duct Characterization of Fluid Machines with Applications to Medium Speed IC-engines
Open this publication in new window or tab >>Acoustic In-duct Characterization of Fluid Machines with Applications to Medium Speed IC-engines
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The unwanted sound, noise, can lead to health problems, e.g. hearing loss and stress-related problems. A pre-knowledge of noise generation by machines is of great importance due to the ever-shorter product development cycles and stricter noise legislation. The noise from a machine radiates to the environment indirectly via the foundation structure and directly via the surrounding fluid. A fluid machine converts the energy from the fluid into mechanical energy or vice versa. Examples of the fluid machines are internal combustion engines (IC-engines), pumps, compressors, and fans. Predicting and controlling noise from a fluid machine requires a model of the noise sources themselves, i.e. acoustic source data. In the duct systems connected to the fluid machines, the acoustic source interacts strongly with the system boundaries, and the source characteristics must be described using in-duct methods.

Above a certain frequency, i.e. first non-plane wave mode cut-on frequency, the sound pressure varies over the duct cross-section and non-plane waves are introduced. For a number of applications, the plane wave range dominates and the non-plane waves can be neglected. But for machines connected to large ducts, the non-plane wave range is also important. In the plane wave range, one-dimensional process simulation software can be used to predict, e.g. for IC-engines, the acoustic in-duct source characteristics. The high frequency phenomena with non-plane waves are so complicated, however, that it is practically impossible to simulate them accurately. Thus, in order to develop methods to estimate the sound produced, experimental studies are also essential.

This thesis investigates the acoustic in-duct source characterization of fluid machines with applications to exhaust noise from medium speed IC-engines.  This corresponds to large engines used for power plants or on ships, for which the non-plane wave range also becomes important. The plane wave source characterization methods are extended into the higher frequency range with non-plane waves. In addition, methods to determine non-plane wave range damping for typical elements in exhaust systems, e.g. after-treatment devices, are discussed.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. xi, 63 p.
TRITA-AVE, ISSN 1651-7660 ; 2015:86
in-duct, acoustic source, source characterization, IC-engine
National Category
Fluid Mechanics and Acoustics
urn:nbn:se:kth:diva-177341 (URN)978-91-7595-765-4 (ISBN)
Public defence
2015-12-10, sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)

QC 20151119

Available from: 2015-11-19 Created: 2015-11-18 Last updated: 2015-12-14Bibliographically approved

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Åbom, Mats
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Marcus Wallenberg Laboratory MWLCompetence Center for Gas Exchange (CCGEx)
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