Sökning: "acoustic scattering matrix"

Visar resultat 1 - 5 av 12 avhandlingar innehållade orden acoustic scattering matrix.

  1. 1. Assessing precision and accuracy in acoustic scattering matrix measurements

    Författare :Luck Peerlings; Hans Bodén; Susann Boij; Avraham Hirschberg; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; aero-acoustics; sudden area expansion; in-duct acoustics; acoustic scattering matrix; impedance tube; uncertainty analysis; systematic errors; Vehicle and Maritime Engineering; Farkostteknik;

    Sammanfattning : Acoustic scattering matrices are used to characterize the influence of inline duct elements on the acoustic wave propagation in wave guides.When measuring the properties of these matrices, errors are always present in the results and need to be characterized to make valid statements on the correspondence between model predictions and measurements. LÄS MER

  3. 2. Experimental Investigation of the Acoustic Properties of Perforate using Acoustic Three-Ports

    Författare :Shail A. Shah; Susann Boij; Hans Bodén; Wim De Roeck; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Duct Acoustics; Acoustical Three-port; Perforated plate; Transfer Impedance; Scattering Matrix; Grazing Flow; High-level Excitation; Non-linear effects; Flow-Acoustic Interaction; Rectangular T-Junction; Farkostteknik; Vehicle and Maritime Engineering;

    Sammanfattning : This thesis discusses the aero-acoustic characterisation of a perforate sample using a three-port technique. A rectangular T-junction with a flush mounted perforated sample at the intersection form the acoustical three-port. LÄS MER

  4. 3. Rough Scatterers in Acoustics and Elastodynamics

    Författare :Per-Åke Jansson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; acoustic scattering; penny-shaped crack; rough surfaces; elastodynamic scattering; T matrix; null field approach;

    Sammanfattning : The purpose of this thesis is to investigate the influence of roughness on wave scattering from finite-sized surfaces, in particular elastic wave scattering from cracks. Acoustic scattering from a sphere is considered using the null field approach. LÄS MER

  5. 4. Experimental Determination of Aeracoustic Sources in Low Mach Number Internal Flows

    Författare :Andreas Holmberg; Hans Bodén; Lars Enghardt; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Aeracoustics; ducts; N-ports; scattering matrix; wave decomposition; source determination; over-determination; flow noise; fluid-acoustic interaction; fluid-structure-acoustic interaction; wave number; T-junction; power balance; grazing-bias flow; Acoustics; Akustik; Vehicle engineering; Farkostteknik;

    Sammanfattning : In this thesis, the in-duct experimental methods for determining aeroacoustic N-ports of in-duct elements are discussed and improved. The scattering matrix determination methods and the related wave decomposition methods are evaluated from measurements in an empty duct carrying a mean flow. LÄS MER

  7. 5. Methods and techniques for precise and accurate in-duct aero-acoustic measurements : Application to the area expansion

    Författare :Luck Peerlings; Susann Boij; Hans Bodén; Yves Aurégan; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Area-expansion; Scattering matrix; Multi-microphone method; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : During the design and commissioning of combustion equipment, combustion associated instabilities are commonly encountered. These thermo-acoustic instabilities can cause undesirable noise, vibrations, local thermal and mechanical stresses in the combustor and are prominent in lean combustion. LÄS MER