Search for dissertations about: "Acoustic Boundary Conditions"

Showing result 1 - 5 of 45 swedish dissertations containing the words Acoustic Boundary Conditions.

  2. 1. Computational Aeroacoustics Based on Large Eddy Simulation and Acoustic Analogies

    Author : Mihai Mihaescu; Laszlo Fuchs; Strömningsteknik; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Mechanical engineering; hydraulics; plasma; Technological sciences; Teknik; fluiddynamik; plasmas; Gaser; fluid dynamics; Gases; Inhomogeneous Wave Equation; Acoustic Boundary Conditions; Acoustic Source Terms; LES; Computational Aeroacoustics; Turbulent Flows; vacuum technology; vibration and acoustic engineering; Maskinteknik; hydraulik; vakuumteknik; vibrationer; akustik; Computational Aeroacoustics;

    Abstract : The thesis presents a numerical method developed by the author and its applications for computing the generated sound by an unsteady flow field and its propagation. The full equations of motion for compressible and unsteady flows describe both flow field and sound generation and propagation. READ MORE

  4. 2. Numerical Methods for Aeroacoustic Analysis of Turbomachines

    Author : Daniel Lindblad; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Stability Analysis; Acoustic Analogy; Tonal Noise; Nonreflecting Boundary Conditions; Duct Modes; Turbomachinery; Harmonic Balance; Ffowcs Williams - Hawkings; Time Sampling; Aliasing;

    Abstract : Numerical simulations are important tools for developing new aircraft that can meet future needs. When numerical simulations are used to compute aircraft noise, a two-step procedure is often employed. In the first step, the noise sources are determined using, e.g. READ MORE

  5. 3. Numerics of Elastic and Acoustic Wave Motion

    Author : Kristoffer Virta; Gunilla Kreiss; Anders Petersson; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; finite differences; stability; high order accuracy; elastic wave equation; acoustic wave equation; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

    Abstract : The elastic wave equation describes the propagation of elastic disturbances produced by seismic events in the Earth or vibrations in plates and beams. The acoustic wave equation governs the propagation of sound. READ MORE

  6. 4. Developing Computational Tools for Modern Aeroacoustic Research

    Author : Mirela Caraeni; Strömningsteknik; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Thermal engineering; unstructured mesh; termoacoustic; acoustic; cfd; applied thermodynamics; Termisk teknik; termodynamik;

    Abstract : The thesis presents the author s research on numerical methods for Com-putational Aeroacoustics and the development of computational tools with direct applicability in industry. The designers in the gas-turbine industry, require accurate methods for predicting the onset and the frequencies of dangerous (pressure) oscillations, like the ones which typically occur in Lean Premixed Pre-vaporized (LPP) combustors. READ MORE

  7. 5. Computational analysis and design optimization for acoustic devices

    Author : Abbas Mousavi; Eddie Wadbro; Martin Berggren; Niels Aage; Umeå universitet; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Design optimization; computational analysis; viscothermal acoustics; material distribution topology optimization; acoustic black holes; finite element method;

    Abstract : This thesis focuses on material distribution topology optimization for acoustic waveguides. The limitations of the material distribution approach are discussed in the context of acoustic waveguides with extensive viscous and thermal boundary losses. READ MORE