This report concerns the research, design, implementation and application of an airfoil trailing-edge noise prediction tool in the development of new, quieter airfoil for large-size wind turbine application. The tool is aimed at enabling comparative acoustic performance assessment of airfoils during the early development cycle of new blades and rotors for wind turbine applications. The ultimate goal is to enable the development of quieter wind turbines by the Wind Energy Industry. The task was accomplished by developing software that is simultaneously suitable for comparative design, computationally efficient and user-friendly. The tool was integrated into a state-of-the-art wind turbine design and analysis code that may be downloaded from the web, in compiled or source code form, under general public licensing, at no charge. During the development, an extensive review of the existing airfoil trailing-edge noise prediction models was accomplished, and the semi-empirical BPM model was selected and modified to cope with generic airfoil geometry. The intrinsic accuracy of the original noise prediction model was evaluated as well as its sensitivity to the turbulence length scale parameter, with restrictions imposed accordingly. The criterion allowed comparison of performance of both CFD-RANS and a hybrid solver (XFLR5) on the calculation of the turbulent boundary layer data, with the eventual adjustment and selection of the latter. After all the elements for assembling the method had been selected and the code specified, a collaboration project was made effective between Poli-USP and TU-Berlin, which allowed the seamless coupling of the new airfoil TE noise module, \"PNoise\", to the popular wind turbine design/analysis integrated environment, \"QBlade\". After implementation, the code calculation routines were thoroughly verified and then used in the development of a family of \"silent profiles\" with good relative acoustic and aerodynamic performance. The sample airfoil development study closed the initial design cycle of the new tool and illustrated its ability to fulfill the originally intended purpose of enabling the design of new, quieter blades and rotors for the advancement of the Wind Energy Industry with limited environmental footprint. / Este trabalho descreve a pesquisa de elementos iniciais, o projeto, a implantação e a aplicação de uma ferramenta de predição de ruído de bordo de fuga, no desenvolvimento de aerofólios mais silenciosos para turbinas eólicas de grande porte. O objetivo imediato da ferramenta é permitir a comparação de desempenho acústico relativo entre aerofólios no início do ciclo de projeto de novas pás e rotores de turbinas eólicas. O objetivo mais amplo é possibilitar o projeto de turbinas eólicas mais silenciosas, mas de desempenho aerodinâmico preservado, pela indústria da Energia Eólica. A consecução desses objetivos demandou o desenvolvimento de uma ferramenta que reunisse, simultaneamente, resolução comparativa, eficiência computacional e interface amigável, devido à natureza iterativa do projeto preliminar de um novo rotor. A ferramenta foi integrada a um ambiente avançado de projeto e análise de turbinas eólicas, de código aberto, que pode ser livremente baixado na Web. Durante a pesquisa foi realizada uma ampla revisão dos modelos existentes para predição de ruído de bordo de fuga, com a seleção do modelo semi-empírico BPM, que foi modificado para lidar com geometrias genéricas. A precisão intrínseca do modelo original foi avaliada, assim como sua sensibilidade ao parâmetro de escala de turbulência transversal, com restrições sendo impostas a esse parâmetro em decorrência da análise. Esse critério permitiu a comparação de resultados de cálculo provenientes de método CFD-RANS e de método híbrido (XFLR5) de solução da camada limite turbulenta, com a escolha do último. Após a seleção de todos os elementos do método e especificação do código, uma parceria foi estabelecida entre a Poli-USP e a TU-Berlin, que permitiu a adição de um novo módulo de ruído de bordo de fuga, denominado \"PNoise\", ao ambiente de projeto e análise integrado de turbinas eólicas \"QBlade\". Após a adição, as rotinas de cálculo foram criteriosamente verificadas e, em seguida, aplicadas ao desenvolvimento de aerofólios mais silenciosos, com bons resultados acústicos e aerodinâmicos relativos a uma geometria de referência. Esse desenvolvimento ilustrou a capacidade da ferramenta de cumprir a missão para a qual foi inicialmente projetada, qual seja, permitir à Indústria desenvolver pás mais silenciosas que irão colaborar com o avanço da energia eólica através da limitação do seu impacto ambiental.

L'objectif de ce travail est de modéliser les sources et la propagation atmosphérique du bruit généré par les éoliennes afin de mieux comprendre les caractéristiques de ce bruit à grande distance et d'aider les fabricants d'éoliennes et les développeurs de parc à respecter la réglementation. En couplant des modèles physiques de source aéroacoustique et de propagation, nous sommes capables de prédire les spectres de bruit, ainsi que la directivité et les modulations d'amplitude associées, pour différentes conditions atmosphériques. Le bruit aérodynamique large bande, à savoir le bruit d'impact de turbulence,le bruit de bord de fuite et le bruit de décrochage, est généralement dominant pour les éoliennes modernes. Le modèle analytique d'Amiet est choisi pour prédire le bruit d'impact de turbulence et le bruit de bord de fuite, en considérant plusieurs améliorations par rapport à la théorie initial : 1, une correction empirique pour l'épaisseur du bord d'attaque est introduite dans le calcul du bruit d'impact de turbulence ; 2, un modèle spectral des fluctuations de pression pariétale proposé récemment pour un écoulement avec gradient de pression défavorable est utilisé dans le calcul du bruit de bord de fuite. Ces modèles sont validés par comparaison avec des mesures de la littérature en soufflerie avec des profils fixes.Le modèle d'Amiet est ensuite appliqué à une éolienne complète pour prédire le bruit émis en champ proche. L'effet de la rotation des pales et l'effet Doppler sont pris en compte. On utilise d'abord des profils de vent constant sans turbulence, puis l'effet du cisaillement du vent et de la turbulence atmosphérique sont inclus à l'aide de la théorie de la similitude de Monin-Obukhov. De bons accords sont obtenus avec des mesures sur site éolien lorsque l'on considère à la fois les bruits de bord de fuite et d'impact de turbulence. On retrouve à l'aide du modèle les caractéristiques classiques du bruit des éoliennes, comme la directivité et les modulations d'amplitude. Des comparaisons avec un modèle semi-empirique montrent que le bruit de décrochage peut être significatif dans certains conditions.L'étape suivante consiste à coupler la théorie d'Amiet avec des modèles de propagation pour estimer le bruit à un récepteur en champ lointain. On étudie dans un premier temps un modèle analytique de propagation en conditions homogènes au-dessus d'un sol d'impédance finie. On montre que l'effet de sol modifie la forme des spectres de bruit, et augmente les modulations d'amplitude dans certains tiers d'octave. Dans un second temps, une méthode pour coupler le modèle de source à un code d'équation parabolique est proposée et validée pour prendre en compte les effets de réfraction atmosphérique. En fonction de la direction de propagation, les niveaux de bruit varient car l'effet de sol est influencé par les gradients de vent et car une zone d'ombre est présente dans la direction opposée au vent. On discute pour finir l'approximation de source ponctuelle à l'aide des modèles de propagation analytique et numérique. / The purpose of this work is to model wind turbine noise sources and propagation in the atmosphere in order to better understand the characteristics of wind turbine noise at long range and to help wind turbine manufacturers and wind farm developers meet the noise regulations. By coupling physically-based aeroacoustic source and propagation models, we are able to predict wind turbine noise spectra, directivity and amplitude modulation in various atmospheric conditions.Broadband noise generated aerodynamically, namely turbulent inflow noise, trailing edge noise and separation/stall noise, is generally dominant for a modern wind turbine. Amiet's analytical model is chosen to predict turbulent inflow noise and trailing edge noise, considering several improvements to the original theory: 1, an empirical leading edge thickness correction is introduced in the turbulent inflow noise calculation; 2, a wall pressure fluctuation spectrum model proposed recently for adverse pressure gradient flow is used in the trailing edge noise predictions. The two models are validated against several wind tunnel experiments from the literature using fixed airfoils.Amiet's model is then applied on a full-size wind turbine to predict the noise emission level in the near field. Doppler effect and blade rotation are taken into account. Cases with constant wind profiles and no turbulence are used first, then wind shear and atmospheric turbulence effects obtained from Monin-Obukhov similarity theory are included. Good agreements against field measurements are found when both turbulent inflow noise and trailing edge noise are considered. Classical features of wind turbine noise, such as directivity and amplitude modulation, are recovered by the calculations. Comparisons with a semi-empirical model show that separation noise might be significant in some circumstances.Next, Amiet's theory is coupled with propagation models to estimate noise immission level in the far-field. An analytical model for the propagation over an impedance ground in homogeneous conditions is studied first. The ground effect is shown to modify the shape of the noise spectra, and to enhance the amplitude modulation in some third octave bands. A method to couple the source model to a parabolic equation code is also proposed and validated to take into account atmospheric refraction effects. Depending on the propagation direction, noise levels vary because the ground effect is influenced by wind shear and a shadow zone is present upwind. Finally, the point source assumption is reviewed considering both the analytical and numerical propagation models.