Sökning: "acoustics"

Visar resultat 1 - 5 av 849 avhandlingar innehållade ordet acoustics.

  1. 1. Flow Duct Acoustics An LES Approach

    Författare :Emma Alenius; Mats Åbom; Laszlo Fuchs; Oliver Paschereit; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; aero-acoustics; duct-acoustics; sound generation; acoustic scattering; acoustic-flow interaction; LES; IC-engines; orifice plate; confined jet;

    Sammanfattning : The search for quieter internal combustion engines drives the quest for a better understanding of the acoustic properties of engine duct components. Simulations are an important tool for enhanced understanding; they give insight into the flow-acoustic interaction in components where it is difficult to perform measurements. LÄS MER

  2. 2. The influence of tyre air cavities on vehicle acoustics

    Detta är en avhandling från Stockholm : KTH

    Författare :Èric Torra i Fernàndez; Anders Nilsson; Wim Desmet; [2006]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; acoustics; tyre-road noise; tyre; air cavity resonances; interior noise; aluminium foams; TECHNOLOGY Engineering physics Acoustics; TEKNIKVETENSKAP Teknisk fysik Akustik;

    Sammanfattning : The tonal character of the low frequency internal noise in cars is often due to energy transmission through the tyre at the first few eigenfrequencies of the air cavity of the tyre. The first acoustic mode in the air cavity of a typical stationary car tyre is approximately 224 Hz. LÄS MER

  3. 3. Acoustical properties of earplugs

    Detta är en avhandling från Engineering Acoustics, LTH, Lund University

    Författare :Per Hiselius; [2005]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Maskinteknik; hydraulik; vakuumteknik; vibrationer; akustik; vibration and acoustic engineering; vacuum technology; hydraulics; Mechanical engineering; acoustic modelling; objective measurement; insertion loss; earplugs; HPE; HPD; hearing protectors; Two-Port; Four-Pole; attenuation; electro acoustics; acoustics;

    Sammanfattning : In this study an experimental setup for measurements of high impedance objects in ducts, yielding the acoustical Two-Port properties of the object, is applied to earplugs. A frequently used experimental setup for measuring objective acoustical properties of earplugs is that of artificial ears. Great effort is spent on duplicating the human ear. LÄS MER

  4. 4. Micro-Structure Modelling of Acoustics of Open Porous Material

    Detta är en avhandling från Stockholm : KTH Royal Institute of Technology

    Författare :Eva Lundberg; Peter Göransson; Per Wennhage; Ulf Orrenius; Camille Perrot; [2016]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; acoustics; porous material; flow resistivity; micro-structure; anisotropic; foam; strut; Farkostteknik; Vehicle and Maritime Engineering;

    Sammanfattning : Transportation is a large and growing part of the world’s energy consumption. This drives a need for reduced weight of rail vehicles, just as it does for road vehicles. In spite of weight reductions, the vehicle still has to provide the same level of acoustic comfort for the passengers. LÄS MER

  5. 5. Experimental and Numerical Multi-port Eduction for Duct Acoustics

    Detta är en avhandling från Stockholm : KTH Royal Institute of Technology

    Författare :Stefan Sack; Abom Mats; Phillip Joseph; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; acoustics; aeroacoustics; flowacoustics; multi-ports; orifice; silencer; experiment; numeric; IDDES; LNSE; optimization; test rig; Monte Carlo; Teknisk mekanik; Engineering Mechanics;

    Sammanfattning : Sound generation and propagation in circular ducts for frequencies beyond the cut-on frequencies of several higher order acoustic modes is investigated. To achieve this, experimental and numerical set-ups are designed and used to research aeroacoustic interactions between in-duct components and to conceive noise mitigation strategies. LÄS MER