Searched for: subject%3A%22Aeroacoustics%22
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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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Zamponi, R. (author)
The interaction of an airfoil with incident turbulence is an important source of aerodynamic noise in numerous applications, such as turbofan engines, cooling systems for automotive and construction industries, high-lift devices on aircraft wings, and landing gear systems. In these instances, turbulence is generally produced by elements that are...
doctoral thesis 2021
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Merino Martinez, R. (author), Kennedy, John (author), Bennett, Gareth J. (author)
The landing gear system is the dominant airframe noise source for most modern commercial aircraft during approach. This manuscript reports the results from the ALLEGRA (Advanced Low Noise Landing (Main and Nose) Gear for Regional Aircraft) project. This project assessed the performance of several highly realistic low–noise technologies (LNTs)...
journal article 2021
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Casalino, D. (author), Grande, E. (author), Romani, G. (author), Ragni, D. (author), Avallone, F. (author)
Experimental and numerical results of a propeller of 0.3 m diameter operated at 5000 RPM and axial velocity ranging from 0 to 20 m/s and advance ratio ranging from 0 to 0.8 are presented as a preliminary step towards the definition of a benchmark configuration for low Reynolds number propeller aeroacoustics. The corresponding rotational tip...
journal article 2021
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Lima Pereira, L.T. (author), Merino Martinez, R. (author), Ragni, D. (author), Gómez-Ariza, David (author), Snellen, M. (author)
This paper explores the advantages of combining asynchronous microphone array measurements for acoustic source mapping in two and three–dimensional applications. Four different approaches are considered, three consisting of the combination of the source maps (arithmetic mean, geometric mean, and minimum value), and a fourth one obtained by...
journal article 2021
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Rego, Leandro (author), Ragni, D. (author), Avallone, F. (author), Casalino, D. (author), Zamponi, R. (author), Schram, Christophe (author)
This paper investigates the application of flow-permeable materials as a solution for reducing jet-installation noise. Experiments are carried out with a flat plate placed in the near field of a single-stream subsonic jet. The flat plate is modular and the solid surface near the trailing edge can be replaced with different flow-permeable...
journal article 2021
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VanDercreek, Colin (author), Merino Martinez, R. (author), Sijtsma, P. (author), Snellen, M. (author)
Aeroacoustic measurements performed by flush-mounted microphone arrays on the walls of closed-section wind tunnels are contaminated by the hydrodynamic pressure fluctuations of the wall's boundary layer. This study evaluates three different microphone cavity geometries for mitigating this issue. Their improvement to the signal-to-noise ratio ...
journal article 2021
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Merino Martinez, R. (author), Rubio Carpio, A. (author), Lima Pereira, L.T. (author), van Herk, S.W.L. (author), Avallone, F. (author), Ragni, D. (author), Kotsonis, M. (author)
The newly refurbished vertical tunnel (V-tunnel) at Delft University of Technology has been redesigned as a state-of-the-art facility for research in aeroacoustics (A-tunnel), as well as fundamental studies in laminar-turbulent transition and flow control. This manuscript focuses on the design and refurbishment aspects of the facility,...
journal article 2020
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Dighe, V.V. (author), Avallone, F. (author), van Bussel, G.J.W. (author)
Ducted Wind Turbines (DWTs) can be used for energy harvesting in urban areas where non-uniform inflows might be the cause of aerodynamic and acoustic performance degradation. For this reason, an aerodynamic and aeroacoustic analysis of DWTs in yawed inflow condition is performed for two duct geometries: a baseline commercial DWT model, DonQi®...
journal article 2020
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Avallone, F. (author), Ragni, D. (author), Casalino, D. (author)
Lattice-Boltzmann Very-Large-Eddy Simulations of two Diffuser-Augmented Wind Turbines are carried out to investigate the effect of the tip-clearance (TC) ratio on both the flow field and the far-field noise. The DonQi® wind turbine, a three blades ducted rotor with nominal TC of 2.5%, is chosen as reference test case. The second configuration...
journal article 2020
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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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Merino Martinez, R. (author), Luesutthiviboon, S. (author), Zamponi, R. (author), Rubio Carpio, A. (author), Ragni, D. (author), Sijtsma, P. (author), Snellen, M. (author), Schram, Christophe (author)
In this paper, the performance of four acoustic imaging methods: conventional frequency domain beamforming (CFDBF), functional beamforming (FUNBF), enhanced high resolution CLEAN–SC (EHR–CLEAN–SC) and generalized inverse beamforming (GIBF), is investigated in terms of accuracy and variability. Three experimental test cases are considered: 1)...
journal article 2020
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Teruna, C. (author), Manegar, F.A. (author), Avallone, F. (author), Ragni, D. (author), Casalino, D. (author), Carolus, T. (author)
Open-cell porous materials have been reported as a promising concept for mitigating turbulent boundary-layer trailing-edge noise. This manuscript examines the aeroacoustics of a porous trailing edge to study its noise reduction mechanisms. Numerical investigations have been carried out for a NACA 0018 aerofoil with three different types of...
journal article 2020
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Romani, G. (author), Ye, Q. (author), Avallone, F. (author), Ragni, D. (author), Casalino, D. (author)
Aim of this paper is to investigate the effects of the turbulent flow developing over a fuselage on fan noise for BLI embedded propulsion systems. Such configurations can suffer from inlet flow distortions and ingestion of turbulence at the fan plane with consequent impact on both broadband and tonal fan noise. The analysis is performed on a...
journal article 2020
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Rego, L. (author), Avallone, F. (author), Ragni, D. (author), Casalino, D. (author)
The link between jet-installation noise and the near-field flow features of the corresponding isolated jet is studied by means of lattice-Boltzmann numerical simulations. The computational set-up consists of a flat plate placed in proximity to a jet, replicating the interaction benchmark study carried out at NASA Glenn. Installation effects...
journal article 2020
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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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Merino Martinez, R. (author), Sijtsma, P. (author), Snellen, M. (author), Finez, A. (author), Herold, G. (author), Malgoezar, A.M.N. (author), Pereira, A. (author), Sarradj, E. (author), Simons, D.G. (author)
Phased microphone arrays have become a well-established tool for performing aeroacoustic measurements in wind tunnels (both open-jet and closed-section), flying aircraft, and engine test beds. This paper provides a review of the most well-known and state-of-the-art acoustic imaging methods and recommendations on when to use them. Several...
journal article 2019
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Romani, G. (author), Casalino, D. (author)
The aim of this paper is to assess the accuracy, capabilities and computational performances of the Lattice-Boltzmann/Very Large Eddy Simulation Method to predict the unsteady aerodynamic loads, the rotor wake development and the noise radiation of helicopter rotors in strong Blade-Vortex Interaction conditions. The numerical flow solution is...
journal article 2019
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Merino Martinez, R. (author)
With the continuous growth in demand for air traffic and wind turbines, the noise emissions they generate are becoming an increasingly important issue. To reduce their noise levels, it is essential to obtain accurate information about all the sound sources present. Phased microphone arrays and acoustic imaging methods allow for the estimation of...
doctoral thesis 2018
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Kurelek, J.W. (author), Kotsonis, M. (author), Yarusevych, S. (author)
Transition and flow development in a separation bubble formed on an airfoil are studied experimentally. The effects of tonal and broadband acoustic excitation are considered since such acoustic emissions commonly result from airfoil self-noise and can influence flow development via a feedback loop. This interdependence is decoupled, and the...
journal article 2018
Searched for: subject%3A%22Aeroacoustics%22
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