Sökning: "Lars Enghardt"

Hittade 4 avhandlingar innehållade orden Lars Enghardt.

  1. 1. Analysis of Acoustic Absorption with Extended Liner Reaction and Grazing Flow

    Författare :Anna Färm; Mats Åbom; Lars Enghardt; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Sound absorption; acoustic lining; non-locally reacting; boundary layer; grazing flow; sound field; transfer matrix method;

    Sammanfattning : Acoustic absorbing liners are efficient and commonly used measures to reduce sound levels in many fields of application. The sound reducingperformance of the liners is dependent on the acoustic state, defined by e.g. the flow and sound field interacting with the liner. LÄS MER

  3. 2. Aeroacoustic Characterization using Multiport Methods

    Författare :Andreas Holmberg; Hans Bodén; Mats Åbom; Susann Boij; Lars Enghardt; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Aeroacoustics; Multiport; Experiments; Computational Aeroacoustics; Mixer Plate; T-junction.;

    Sammanfattning : Noise is a major environmental pollutant, which can inict physical and psychologicalinjury. An important noise contribution stems from aeroacousticsources, which are found in e.g., ventilation ducts, engine exhaust systems andairplane engines. LÄS MER

  4. 3. 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

  5. 4. Optimal damping and slow sound in ducts

    Författare :Zhe Zhang; Mats Åbom; Hans Bodén; Lars Enghardt; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Vehicle and Maritime Engineering; Farkostteknik;

    Sammanfattning : The thesis is dedicated to expanding knowledge on two duct acoustic issues including: 1) the optimal damping of low frequency sound and 2) the development and application of ‘slow sound’.To address the first issue, the ‘Cremer impedance’ proposed more than half a century ago has been revisited and further developed. LÄS MER