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Avallone, F. (author), Ragni, D. (author)
Noise reduction is one of the major challenges to the societal acceptance of wind turbines. Aerodynamic noise sources are the dominant ones, assuming that mechanical noise can be reduced by correct insulation and periodic maintenance of the gearbox and drive train and by adding insulating material in the wind-turbine nacelle. The dominant...
book chapter 2023
document
Utzmann, J. (author), Munz, C.D. (author)
This paper advances the idea of a heterogeneous domain decomposition for Computational Aeroacoustics (CAA). Direct simulations of aeroacoustic problems are accelerated by sub-dividing the computational domain into smaller domains. In each of these sub-domains the equations, the discretization, the mesh and the time step may be different and are...
conference paper 2006
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Lörcher, F. (author), Gassner, G. (author), Munz, C.D. (author)
Numerical schemes for wave propagation over long distances need good wave propagation properties with low dispersion and low dissipation errors. Suitable numerical methods are methods with high order of accuracy in space and time. For space discretization on structured grids, high order finite difference schemes are efficient, and, if a...
conference paper 2006
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Taghaddosi, F. (author), Habashi, W.G. (author)
A three-dimensional computational aeroacoustics code has been developed for the simulation of tone noise generated by turbofan engine inlets. The code is based on the linearized Euler equations, rewritten in terms of acoustic potential and solved in the frequency domain. Spatial discretization is performed using a spectral element method....
conference paper 2006
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Bernacki, M. (author), Piperno, S. (author)
We present in this paper a time-domain Discontinuous Galerkin dissipation-free method for the transient solution of the three-dimensional linearized Euler equations around a steady-state solution. In the general context of a non-uniform supporting flow, we prove, using the well-known symmetrization of Euler equations, that some aeroacoustic...
conference paper 2006
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Arina, R. (author), Ceresola, N. (author)
A numerical simulation of the turbulent flow field of a transonic cavity and its associated far-field sound radiation, are presented. The test case is based on the experimental case M219 of QinetiQ. Two different turbulent simulations are performed, the first one is a URANS simulation with a k-w-EARSM turbulence model. while a DES turbulence...
conference paper 2006
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Ragni, D. (author), Avallone, F. (author), van der Velden, W.C.P. (author)
The far-field noise and flow field of a novel curved trailing-edge serration (i.e. iron-shaped) are investigated. Spectra of the far-field broadband noise, directivity plots and the flow-field over the iron-shaped serration are obtained from numerical computations performed using a compressible Lattice-Boltzmann solver. The new design is...
conference paper 2017
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Moore, P.D. (author)
Jet noise is an extensively studied phenomenon since the deployment of the first civil jet aircraft more than 50 years ago. Jet noise makes up a considerable portion of the total noise of jet aircraft, and the expansion of the numbers of airplanes and airports has only been possible by keeping the noise of airplanes under control. However, while...
doctoral thesis 2009
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Pröbsting, S. (author)
Noise generated aerodynamically by the airflow over a lifting surface is often of concern for applications as diverse as air and ground transportation, heating, ventilation, air-conditioning systems, and wind turbines. The thesis describes the application of advanced optical flow measurements techniques for the visualization and description of...
doctoral thesis 2015
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De Jong, A.T. (author)
doctoral thesis 2012
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Koschatzky, V. (author)
This thesis deals with the problem of noise. Sound is a constant presence in our lives. Most of the times it is something wanted and it serves a purpose, such as communication through speech or entertainment by listening to music. On the other hand, quite often sound is an annoying and unwanted by-product of some other activity necessary to us....
doctoral thesis 2011
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Testa, C. (author)
doctoral thesis 2008
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Malgoezar, A.M.N. (author)
Humans localize sound incessantly using the ears and it proves to be important of<br/>our awareness. It can also be a cause of annoyance to the community whenever<br/>sound is in the form of noise. Due to increase of wealth, industry, technology and<br/>corresponding globalization there is a large increase of noise. Especially with the<br/...
doctoral thesis 2019
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Dighe, V.V. (author)
Ducted Wind Turbines (DWTs) are one of the many concepts that have been proposed to improve the energy extraction from wind in comparison to bare wind turbines. In reviewing the DWT studies, investigations based on the combined use of theoretical, computational, and experimental techniques have been presented. Although indicated in these studies...
doctoral thesis 2020
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Lima Pereira, L.T. (author)
Wind-turbine noise can restrict the growing implementation of renewable energy sources and their application close to urban environments. The largest contributor to the noise of modern turbines is the scattering of the turbulent fluctuations at the blade trailing edge. This source of noise is directly correlated with the turbine’s extracted...
doctoral thesis 2023
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Yunus, F. (author)
doctoral thesis 2023
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Teruna, C. (author)
Public annoyances due to noise emission in aviation and wind energy sectors are expected to become more severe in the near future with increasing number of civilian flights and wind turbine installations. Such trend demands for deeper investigations into the noise generation mechanisms and the means to mitigate them. This dissertation addresses...
doctoral thesis 2022
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Brandetti, L. (author)
In urban areas, vertical-axis wind turbines (VAWTs) show promise due to their omnidirectional design, addressing challenges faced by traditional horizontal-axis turbines (HAWTs). Despite significant progress in urban VAWTs, extensive multidisciplinary research is needed to optimise their efficiency and use in such environments. <br/><br/>This...
doctoral thesis 2024
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Lorenzoni, V. (author), Ragni, D. (author)
An experimental study of the flow inside a saxophone mouthpiece in playing conditions is carried out by means of particle image velocimetry at high acquisition rate. Planar velocity measurements on the midsection of a Plexiglas tenor saxophone mouthpiece are performed, respectively, in the mouthpiece baffle and in the reed channel. Sequences of...
journal article 2012
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Violato, D. (author), Scarano, F. (author)
The three-dimensional behavior of jet core breakdown is investigated with experiments conducted on a free water jet at Re = 5000 by time-resolved tomographic particle image velocimetry (TR-TOMO PIV). The investigated domain encompasses the range between 0 and 10 jet diameters. The characteristic pulsatile motion of vortex ring shedding and...
journal article 2013
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