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Acoustic Simulation of Medium Speed IC-Engine Exhaust Gas After Treatment Devices with Substrate
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. VTT Technical Research Centre of Finland Ltd. (Flow acoustics)
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.ORCID iD: 0000-0001-7898-8643
2014 (English)Other (Refereed)
Abstract [en]

The after treatment devices (ATD) used in internal combustion engine (IC-engine) exhaust systems are mainly designed with emphasis on emission control, i.e. chemical efficiency, while paying less attention to the acoustic performance. In automotive applications, the duct diameters are so small that studying the acoustic wave propagation only in the plane wave frequency range is usually sufficient. In the case of medium speed IC-engines, used for example in power plants and ships, the three dimensional acoustic phenomena must also be taken into account. The main elements of the medium speed IC-engine ATD are the selective catalytic reducer (SCR) and oxidation catalyst (OC), which are based on a large amount of coated channels, i.e. the substrates. The number and type of the substrates depends not only on the regional environment legislations but also on the engine type. In this study the acoustic attenuation of a medium speed IC-engine ATD is simulated and the results are compared with measurements. The focus is in the low and mid frequency range. That is, the three dimensional waves inside the ATD are taken into account whereas only the plane waves are assumed to propagate at the inlet and outlet ports. The paper also discusses how to extend the classical one dimensional two-port solution into the higher frequencies. Using the computationally effective two-port solution in a wider frequency range is of great importance, e.g., when searching the acoustically optimal substrate configuration.

Place, publisher, year, pages
SAE International , 2014.
Series
SAE Technical Paper
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-177337DOI: 10.4271/2014-01-2057OAI: oai:DiVA.org:kth-177337DiVA: diva2:872288
Note

QC 20151214

Available from: 2015-11-18 Created: 2015-11-18 Last updated: 2015-12-14Bibliographically 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.
Series
TRITA-AVE, ISSN 1651-7660 ; 2015:86
Keyword
in-duct, acoustic source, source characterization, IC-engine
National Category
Fluid Mechanics and Acoustics
Identifiers
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)
Opponent
Supervisors
Note

QC 20151119

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

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