Searched for: subject%3A%22trailing%255C%2Bedge%255C%2Bnoise%22
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Fiscaletti, D. (author), Lima Pereira, L.T. (author), Ragni, D. (author)
The present study focuses on the application of finlet rails as a passive technique of flow control to mitigate trailing-edge noise. Finlet rails are small cylinders whose axes are aligned along the streamwise direction, transversally positioned with respect to the trailing edge. In the first part of this study, the effects of finlet geometry...
journal article 2024
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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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Bouman, Naomi (author)
Airborne wind energy systems offer a promising approach for renewable energy generation. However, the noise emissions associated with these systems should be understood and minimized as well to promote their integration and (social) acceptance. This research aims to identify the noise sources of airborne wind energy systems, systems with leading...
master thesis 2023
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Lima Pereira, L.T. (author), Avallone, F. (author), Ragni, D. (author), Scarano, F. (author)
This work discusses the physics of noise reduction achieved from serrated trailing–edges and its impact by the serration design. An experimental campaign is carried out with a benchmark 2D model based on a NACA 63<sub>3</sub>–018 airfoil. Different trailing-edge serrations are tested under several flow speeds and angles of attack conditions...
journal article 2023
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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
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Luesutthiviboon, S. (author)
Nowadays, large wind turbines are installed and operated close to densely populated areas due to the growing need for renewable energy. Noise constraints are hampering this development. The most relevant wind turbine noise source is the so-called Turbulent Boundary Layer Trailing-Edge (TBL–TE) noise. Many passive TBL–TE noise reduction...
doctoral thesis 2022
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Vergés i Plaza, Guillem (author)
Trailing-edge noise can be the dominant noise source of diverse industrial applications, including wind turbines. Noise regulations may limit the power production and installation of new wind farms. There is a need to reduce it. In order to achieve so, we first need to predict it, and to do so we need experimental data to support and validate...
master thesis 2022
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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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Romani, G. (author)
The accurate and reliable prediction of the aerodynamic noise sources of open rotors and ducted-fans in electric Vertical Take-Off and Landing (eVTOL) and non-conventional aircraft configurations is a challenging task from a computational perspective. Indeed, such propulsive systems can often operate in highly distorted and non-homogeneous flows...
doctoral thesis 2022
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Rubio Carpio, A. (author)
Permeable trailing edges are experimentally investigated in this thesis as a mean tomitigate aeroacoustic noise. The first part of the study is devoted to deciphering themechanisms of noise generation involved in these devices. To this aim, trailing-edge inserts are manufactured employing commercially-produced open-cell metallic foams with...
doctoral thesis 2021
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Khan, Y. (author)
An experimental study is conducted on the design of actively controlled semi-permeable inserts for mitigating turbulent boundary layer noise originating from the trailing edge of an airfoil. Two sets of perforated inserts with hole diameter: 0.8 mm and hole spacing: 1.5 mm &amp; 3 mm, are considered. The inserts are 3-D printed with a middle...
master thesis 2020
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Rubio Carpio, A. (author), Avallone, F. (author), Ragni, D. (author), Snellen, M. (author), van der Zwaag, S. (author)
An experimental study on broadband noise scattered by permeable trailing edges with different pore arrangements is performed. A NACA 0018 airfoil with chord c = 0.2 m is investigated at chord-based Reynolds numbers ranging from 1.4 × 10<sup>5</sup> to 3.8 × 10<sup>5</sup> and angles of attack of 0.2 and 5.4 degrees. Noise emission from five...
journal article 2020
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Mayer, Jonathan (author), Rubio Carpio, A. (author), Ragni, D. (author)
The present work analyses broadband noise scattering from permeable trailing edges with identical micro-structure but under a change of temperature. Experiments are performed in an anechoic wind tunnel using a NACA0018 airfoil at chord-based Reynolds numbers between 1.88 × 10<sup>5</sup> and 3.14 × 10<sup>5</sup> and no incidence. A...
journal article 2019
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Mayer, Jonathan (author)
For many aerospace applications, the dominant airfoil self-noise source is Turbulent Boundary Layer Trailing Edge (TBL-TE) noise. The replacement of solid airfoil trailing edges with permeable materials proved to be an adequate noise reduction mean in previous studies. This thesis project contributes to the development of innovative permeable...
master thesis 2019
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Rubio Carpio, A. (author), Merino Martinez, R. (author), Avallone, F. (author), Ragni, D. (author), Snellen, M. (author), van der Zwaag, S. (author)
The hydrodynamic and acoustic fields for a NACA 0018 with solid and porous trailing edge inserts are investigated. The porous inserts, covering 20% of the chord, are manufactured with metal foams with cell diameters of 450 and 800 μm and permeability values of 6 × 10−10 and 2.7 × 10−9 m2. The experiments are performed at a chord-based Reynolds...
journal article 2019
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Merino Martinez, R. (author), Sijtsma, P. (author), Rubio Carpio, A. (author), Zamponi, R. (author), Luesutthiviboon, S. (author), Malgoezar, A.M.N. (author), Snellen, M. (author), Schram, Christophe (author), Simons, D.G. (author)
Most acoustic imaging methods assume the presence of point sound sources and, hence, may fail to correctly estimate the sound emissions of distributed sound sources, such as trailing-edge noise. In this contribution, three integration techniques are suggested to overcome this issue based on models considering a single point source, a line...
journal article 2019
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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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Avallone, F. (author), van der Velden, W.C.P. (author), Ragni, D. (author)
Far-field noise and flow field over a novel curved trailing-edge serration (named as iron-shaped serration) 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...
journal article 2017
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Rooks, J.J.W. (author)
To investigate the mechanisms of wing trailing edge noise the aeroacoustic sound generation by a NACA 0018 has been computed with direct numerical simulations using the Lattice Boltzmann Method. Noise from the straight trailing edge wing is compared with the sound generated by a sawtooth serrated wing, which reduces the noise emission according...
master thesis 2016
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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
Searched for: subject%3A%22trailing%255C%2Bedge%255C%2Bnoise%22
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