Sökning: "Ffowcs Williams and Hawkings"

Visar resultat 1 - 5 av 11 avhandlingar innehållade orden Ffowcs Williams and Hawkings.

  1. 1. Aerodynamic and Aeroacoustic Analysis of a Multi-Element Airfoil using Hybrid RANS/LES Modeling Approaches

    Författare :Bastian Nebenführ; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Ffowcs-Williams and Hawkings; HYB0; noise; hybrid RANS LES; multi-element airfoil; CAA; Kirchhoff; Curle; high-lift;

    Sammanfattning : Global hybrid RANS/LES simulations were used for computing the turbulent flow around a three-element airfoil. Based on the results of the flow computations, a comprehensive analysis of the flow properties was performed. LÄS MER

  3. 2. 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

  4. 3. A Wave Expansion Method for Aeroacoustic Propagation

    Författare :Johan Hammar; Gunilla Efraimsson; Ciarán J. O'Reilly; Wim De Roeck; KTH; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER

  5. 4. Predicting the sound field from aeroacoustic sources on moving vehicles : Towards an improved urban environment

    Författare :Nicolas Pignier; Ciarán O'Reilly; Susann Boij; Michael Carley; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; pass-by simulations; aeroacoustic sources; urban sound propagation; direct numerical beamforming; linear programming deconvolution; Kirchhoff approximation; moving sources; detached-eddy simulation; Ffowcs Williams-Hawkings; vehicle design; förbifartssimuleringar; aeroakustiska källor; urban ljudutbredning; direkt numerisk lobformning; avfaltning med hjälp av linjärprogrammering; Kirchhoffs approximation; rörliga källor; detached-eddy simulation; Ffowcs Williams-Hawkings; fordonsdesign; Vehicle and Maritime Engineering; Farkostteknik;

    Sammanfattning : In a society where environmental noise is becoming a major health and economical concern, sound emissions are an increasingly critical design factor for vehicle manufacturers. With about a quarter of the European population living close to roads with heavy traffic, traffic noise in urban landscapes has to be addressed first. LÄS MER

  7. 5. Turbomachinery Aeroacoustic Calculations using Nonlinear Methods

    Författare :Martin Olausson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Nonlinear; CFD; Time Spectral; CAA; Ffowcs-Williams Hawkings; Broadband; Time lag; Computational Aeroacoustics; Fan-Noise; Rotor-Stator interaction; Buffer layer; Oscillating sphere; Newton-GMRES; Computational Fluid Dynamics; Acoustic analogies; Sponge; Counter-Rotating Propfan; Harmonic Balance Technique; Tone; FWH; Chorochronic periodicity; Hybrid RANS LES;

    Sammanfattning : Noise regulations for aircraft that fly over populated areas are becoming continuously stricter. This in combination with increasing computational capabilities has boosted interest in aeroacoustic computations in the aerospace industry. LÄS MER