Search for dissertations about: "vortex sound"

Showing result 1 - 5 of 9 swedish dissertations containing the words vortex sound.

  2. 1. Acoustic scattering in ducts and influence of flow coupling

    Author : Susann Boij; KTH; []
    Keywords : sound; vortex sheet; flow separation; end correction; Strouhal number; non-orthogonal modes; energy balance; TECHNOLOGY; TEKNIKVETENSKAP;

    Abstract : The subject of this thesis is the acoustic properties offlow duct area expansions and the influence of flow-acousticcoupling at sharp edges. For low Mach number flow, significantinteraction between the sound field and the flow field canoccur at such points of flow separation. READ MORE

  4. 2. A Wave Expansion Method for Aeroacoustic Propagation

    Author : Johan Hammar; Gunilla Efraimsson; Ciarán J. O'Reilly; Wim De Roeck; KTH; []
    Keywords : ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Sound propagation; Sound generation; Aeroacoustics; Aerodynamics; Computational fluid dynamics; Computational aeroacoustics; Numerical methods; Lighthill; Curle; Ffowcs Williams and Hawkings; Frequency-domain propagation; Wave expansion method.; Vehicle and Maritime Engineering; Farkostteknik;

    Abstract : Although it is possible to directly solve an entire flow-acoustics problem in one computation, this approach remains prohibitively large in terms of the computational resource required for most practical applications. Aeroacoustic problems are therefore usually split into two parts; one consisting of the source computation and one of the source propagation. READ MORE

  5. 3. Aeroacoustics Studies of Duct Branches with Application to Silencers

    Author : Mikael Karlsson; Mats Åbom; Luc Mongeau; KTH; []
    Keywords : ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; silencer; muffler; confined flows; flow duct; aeroacoustics; vortex sound; acoustic multiports; linear stability; self-sustained oscillations; whistling; Herschel-Quincke tube; acoustic resonator; Fluid mechanics; Strömningsmekanik;

    Abstract : New methodologies and concepts for developing compact and energy efficient automotive exhaust systems have been studied. This originates in the growing concern for global warming, to which road transportation is a major contributor. READ MORE

  6. 4. Flow Duct Acoustics : An LES Approach

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

    Abstract : 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. READ MORE

  7. 5. A Study of Subsonic Turbulent Jets and Their Radiated Sound Using Large-Eddy Simulation

    Author : Niklas Andersson; Chalmers University of Technology; []
    Keywords : Two-Point Space-Time Correlations; CAA; Jet Noise; LES; Kirchhoff; Coaxial Jets; Heated Jets; Aeroacoustics;

    Abstract : Stricter noise regulation for near-ground operations has made noise reduction in commercial aircraft a topic of growing interest in the aerospace industry. To meet airworthiness requirements new noise reduction technologies have to be developed and numerical methods for correct assessment of these technologies are desirable. READ MORE