Sökning: "Acoustic Noise Generation"

Visar resultat 1 - 5 av 33 avhandlingar innehållade orden Acoustic Noise Generation.

1. 1. Noise from wind turbines

   Författare :Olivier Fégeant; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; masking; vibration transmission; diffraction; ambient noise; pseudo-noise; cylindrical shell. Perturbation methods; structural mobility; axoustic outdoor measurement; Building engineering; Byggnadsteknik;

   Sammanfattning : A rapid growth of installed wind power capacity is expectedin the next few years. However, the siting of wind turbines ona large scale raises concerns about their environmental impact,notably with respect to noise. LÄS MER

3. 2. Influence of Acoustic Interaction between Cavities That Generate Cavitation Noise

   Författare :Jan Hallander; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; numerical simulation; collapse of vapour cavities; experimental studies; pressure pulses; cavitation noise; hydrodynamics; cavitation; bubbles; cavitating flows;

   Sammanfattning : The thesis concerns high frequency cavitation noise generated by marine propellers, for example. The collapse of a cavity is forced by the surrounding pressure which comprises the pressure in the undisturbed flow, the pressure disturbance associated with the local non-cavitating flow and, finally, the pressure disturbance from the presence and motion of neighbouring cavities. LÄS MER

4. 3. Numerical prediction of propeller induced hull pressure pulses and noise

   Författare :Muye Ge; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; RANS; Transition; IDDES; Cavitation; Pressure pulses; Sheet cavitation inception; Ship noise; k − ω SST; FWH acoustic analogy; Hydroacoustics;

   Sammanfattning : An operating marine propeller is one of the major sources inducing hull pressure pulses, onboard noise and vibration as well as underwater radiated noise. There are rising concerns of environmental impacts and comfort and welfare of passengers and crews due to these negative effects. LÄS MER

5. 4. 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

7. 5. Sound propagation from sustainable ground vehicles : from aeroacoustic sources to urban noise

   Författare :Nicolas Pignier; Ciarán O'Reilly; Susann Boij; Gwenael Gabard; KTH; []
   Nyckelord :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;

   Sammanfattning : 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. LÄS MER