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Investigation of sound reflection from a hot and subsonic flow duct termination
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strömningsakustik. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
Dept. of Machinery, Tallin University of Technology, Tallin, Estonia.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strömningsakustik. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.ORCID-id: 0000-0001-7898-8643
2012 (Engelska)Ingår i: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568Artikel i tidskrift (Övrigt vetenskapligt) Submitted
Ort, förlag, år, upplaga, sidor
2012.
Nyckelord [en]
plane wave reflection, duct termination, hot jet, exhaust system
Nationell ämneskategori
Farkostteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-93042OAI: oai:DiVA.org:kth-93042DiVA, id: diva2:514602
Anmärkning
SQ 2012Tillgänglig från: 2012-04-10 Skapad: 2012-04-10 Senast uppdaterad: 2017-12-07Bibliografiskt granskad
Ingår i avhandling
1. Acoustic Characterization of Turbochargers and Pipe Terminations
Öppna denna publikation i ny flik eller fönster >>Acoustic Characterization of Turbochargers and Pipe Terminations
2012 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

In search for quieter engines there is a need for a better understanding of the acoustic properties of engine intake and exhaust system components. Besides mufflers which have the purpose of reducing pressure pulses originating from the internal combustion (IC) engine, there are many components in a modern car exhaust and intake system, e.g., air-filters, coolers, catalytic converters, particulate filters - all having an effect on the pressure pulses or sound field in the system. In this work the focus is on the turbocharged IC-engine where both, sound scattering (reflection and transmission) and sound generation from automotive turbochargers are studied. In addition, sound reflection from an open ended pipe, such as the tailpipe of an IC-engine exhaust is investigated.

            Accurate and efficient methods to fully characterize turbochargers by measuring the acoustic two-port have been developed.  Compared to earlier work, a number of modifications are suggested for improving the quality of the results. A study on three different automotive turbochargers is also presented, including data for sound scattering for both the compressor and turbine. The results for the transmission of sound, which is of interest for the ability of a turbocharger to reduce noise coming from the engine, is plotted for all tested cases against a dimensionless frequency scale (Helmholtz-number). This makes it possible to generalize the result in order to draw conclusions about the behavior for any turbocharger. 

            The sound generation was also studied and three different methods to estimate the sound power are suggested. The methods were used to investigate sound generation at different operating points and identify source mechanisms for a turbocharger compressor.

            An accurate method for measuring the reflection of plane acoustic waves from a pipe termination in a duct with hot gas flow has been developed and tested. Representing the acoustical conditions at an exhaust tail-pipe, the data obtained is important for effective modeling of exhaust systems. The experimental results of the reflection coefficient were compared with Munt`s theory on flow duct openings. The measurements were carried out for air jet velocities up to Mach 0.4 and for flow temperatures up to 100°C in order to study temperature effects on the reflection properties. It was concluded, that the experimental results agree well with the Munt theory.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2012. s. vi, 24
Serie
Trita-AVE, ISSN 1651-7660 ; 2012:07
Nyckelord
acoustical two-port, turbocharger, transmission loss, sound generation, compressor, turbine, IC-engine, inlet system, exhaust system, flow duct, duct termination, reflection coefficient
Nationell ämneskategori
Farkostteknik
Identifikatorer
urn:nbn:se:kth:diva-92648 (URN)
Presentation
2012-04-13, Seminar room Mechanics, KTH, Brinellvägen 32, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Forskningsfinansiär
TrenOp, Transport Research Environment with Novel Perspectives
Tillgänglig från: 2012-04-10 Skapad: 2012-04-05 Senast uppdaterad: 2013-04-11Bibliografiskt granskad

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Åbom, Mats

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Tiikoja, HeikiRämmal, HansÅbom, Mats
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