Search for dissertations about: "sound scattering"

Showing result 1 - 5 of 34 swedish dissertations containing the words sound scattering.

2. 1. Sound propagation around off-shore wind turbines

   Author : Lisa Johansson; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wind turbine noise; off-shore wind powe; long-rage sound propagation; parabolic equation; scattering; water waves; Building engineering; Byggnadsteknik;

   Abstract : Low-frequency, long-range sound propagation over a seasurface has been calculated using a wide-angel Cranck-NicholsonParabolic Equation method. The model is developed toinvestigate noise from off-shore wind turbines. Thecalculations are made using normal meteorological conditions ofthe Baltic Sea. READ MORE

4. 2. Sound propagation from sustainable ground vehicles : from aeroacoustic sources to urban noise

   Author : Nicolas Pignier; Ciarán O'Reilly; Susann Boij; Gwenael Gabard; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; sound propagation; sound generation; ground vehicle; aeroacoustics; aerodynamics; Kirchhoff approximation; detached eddy simulation; Ffowcs Williams and Hawkings; ljudutberdning; ljudalstring; markfordon; aeroakustik; aerodynamik; Kirchhoff approximation; detached eddy simulation; Ffowcs Williams and Hawkings; Vehicle and Maritime Engineering; Farkostteknik; Engineering Mechanics; Teknisk mekanik;

   Abstract : Transportation is the main source of environmental noise in Europe, with an estimated 125 million people affected by excessive noise levels from road traffic, causing a burden of noise related diseases and having a substantial economic impact on society. In order to reduce exposure to high levels of traffic noise, two approaches are the topic of extensive research: preventing sound from propagating from roads and railways using for example noise barriers, and reducing the sources of noise themselves. READ MORE

5. 3. 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

6. 4. The Influence of Atmospheric Turbulence on Barrier Sound Reduction

   Author : Jens Forssén; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; traffic noise; barrier; measurements; turbulence; scattering cross-section; substitute sources; outdoor sound propagation; parabolic equation method; random media; numerical modelling;

   Abstract : Numerical modelling and measurements are used for studying the reduced performance of a noise barrier, caused by a turbulent atmosphere. The turbulence scatters the sound, which leads to an increased noise level in the acoustic shadow region behind the barrier. READ MORE

7. 5. Flow Duct Acoustics : An LES Approach

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