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Acoustic propagation in a flow duct with an orifice plate
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Aeroakustik.ORCID-id: 0000-0002-9061-4174
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strömningsakustik.ORCID-id: 0000-0003-4103-0129
2008 (Engelska)Ingår i: PROCEEDINGS OF ISMA 2008: INTERNATIONAL CONFERENCE ON NOISE AND VIBRATION ENGINEERING, VOLS. 1-8, 2008, s. 485-495Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

In this paper we present calculations of sound wave propagation in a straight duct with an orifice plate and a mean flow present. The wave propagation is modelled with a frequency domain linearized Navier-Stokes equations methodology. A two-dimensional approximation is used to an axisymmetric cylindrical geometry, and an appropriate frequency scaling is utilized to account for this. The relation between pressure and density is assumed isentropic and correction for duct damping based on viscous dissipation in the acoustic boundary layers is applied. Calculations are carried out for frequencies in the plane wave range up to the cut-on frequency of the first higher order propagating acoustical mode, and performed with a commercial Finite Element Method code on a quadrilateral mesh with third order shape functions. Results of transmission through, and reflections at the orifice are presented on a two-port scattering matrix form and are compared to measurements with good agreement.

Ort, förlag, år, upplaga, sidor
2008. s. 485-495
Nationell ämneskategori
Strömningsmekanik och akustik
Identifikatorer
URN: urn:nbn:se:kth:diva-26118ISI: 000263409900035ISBN: 978-90-73802-86-5 (tryckt)OAI: oai:DiVA.org:kth-26118DiVA, id: diva2:370151
Konferens
International Conference on Noise and Vibration Engineering, Leuven, BELGIUM, SEP 15-17, 2008
Anmärkning
QC 20101115Tillgänglig från: 2010-11-15 Skapad: 2010-11-15 Senast uppdaterad: 2011-09-27Bibliografiskt granskad
Ingår i avhandling
1. Numerical Investigations of Generation and Propagation of Sound Waves in Low Mach Number Internal Flows
Öppna denna publikation i ny flik eller fönster >>Numerical Investigations of Generation and Propagation of Sound Waves in Low Mach Number Internal Flows
2008 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Traffic is a major source of environmental noise in modern day society. Subsequently, development of new vehicles are subject to heavy governmental legislations. The major noise sources on common road vehicles are engine noise, transmission noise, tire noise and, at high speeds, wind noise. At low speeds (< 30-50 km/h), intake and exhaust noise are particularly important during acceleration. One way to reduce intake and exhaust noise is to attach mufflers to the exhaust pipes. However, to develop prototypes of mufflers for evaluation is a costly and time-consuming process. As a consequence, in recent years so-called virtual prototyping has emerged as an alternative. Current industrial simulation methodologies are often rather simple, either neglecting mean flow or including only one-dimensional mean flows. Also, flow generated noise is rudimentary modeled or not included at all. Hence, improved methods are needed to fully benefit from the possibilities of virtual prototyping.

This thesis is divided in two main parts. The first topic is related to the development and evaluation of methods to simulate sound propagation and generation in two-dimensional confined geometries with arbitrary internal mean flows present. The performance of a new DNS code is evaluated for aeroacoustical purposes and a frequency domain linearized Navier-Stokes equations methodology is developed for acoustic wave propagation applications. Both methods are validated on a case of an in-duct orifice plate.

In the second part, a so-called global mode decomposition technique is evaluated for aeroacoustical purposes. The flow field is described as a sum of the non-orthogonal solutions to its corresponding eigenvalue problem. This enables the acoustic analysis of source terms from each individual global mode, and thus reveals new insight into the sound generating mechanisms.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH, 2008. s. vi, 33
Serie
Trita-AVE, ISSN 1651-7660 ; 2008:58
Nationell ämneskategori
Strömningsmekanik och akustik
Identifikatorer
urn:nbn:se:kth:diva-9388 (URN)
Presentation
2008-10-21, MWL 74, Teknikringen 8, KTH, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Anmärkning
QC 20101115Tillgänglig från: 2008-10-30 Skapad: 2008-10-29 Senast uppdaterad: 2010-11-15Bibliografiskt granskad

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Efraimsson, GunillaBoij, Susann

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Kierkegaard, AxelEfraimsson, GunillaBoij, Susann
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Strömningsmekanik och akustik

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