Sökning: "acoustics"

Visar resultat 1 - 5 av 1039 avhandlingar innehållade ordet acoustics.

  1. 1. Flow Duct Acoustics : An LES Approach

    Författare :Emma Alenius; Mats Åbom; Laszlo Fuchs; Oliver Paschereit; KTH; []
    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

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

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

  4. 3. CFD of Duct Acoustics for Turbocharger Applications

    Författare :Emma Alenius; Mats Åbom; Laszlo Fuchs; Federico Piscaglia; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Aero acoustics; Large Eddy Simulation; IC-engines; 1D models; turbocharger; orifice plate; Acoustics; Akustik; Fluid mechanics; Strömningsmekanik;

    Sammanfattning : The search for quieter internal combustion engines drives the quest for a better understanding of the acoustic properties of engine duct components. In this work the main focus is the turbocharger compressor and a discussion of turbocharger acoustics and earlier work within the area is presented, giving an insight into its sound generating mechanisms and the damping effect it has on pressure pulses, i. LÄS MER

  5. 4. IC-engine intake noise predictions based on linear acoustics

    Författare :Magnus Knutsson; Mats Åbom; Antonio Torregrosa; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Acoustics; Akustik;

    Sammanfattning : Shorter product development cycles, densely packed engine compartments and intensified noise legislation increase the need for accurate predictions of IC-engine air intake noise at early stages. The urgent focus on the increasing CO2 emissions and the efficiency of IC-engines, as well as new techniques such as homogeneous charge compression ignition (HCCI) might worsen the noise situation. LÄS MER

  7. 5. Micro-Structure Modelling of Acoustics of Open Porous Material

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

    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