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Hinssen, Yara (author)
Aeroacoustic testing in wind tunnels is crucial for understanding and mitigating the noise generation mechanisms in several devices while maintaining satisfactory aerodynamic performance in the conceptual design stage. However, current measurements in closed-section wind tunnels face challenges in terms of installation, due to the effect of the...
master thesis 2024
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Zamponi, R. (author), Avallone, F. (author), Ragni, D. (author), Schram, C. (author), van der Zwaag, S. (author)
This paper elucidates the link between the near-wake development of a circular cylinder coated with a porous material in a low Mach-number flow and the related aerodynamic sound attenuation. It accomplishes this by formulating the cylinder flow-induced noise as a diffraction problem. The necessity for such an approach is driven by...
journal article 2024
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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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Zhang, Y. (author), Avallone, F. (author), Watson, S.J. (author)
In this paper, the feasibility of using far-field acoustic measurements as a non-contact monitoring technique for wind turbine blade leading edge erosion is assessed. For this purpose, a DU96 W180 airfoil with several eroded leading edge configurations of different severities is experimentally investigated. The eroded leading edges are designed...
journal article 2023
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VanDercreek, Colin (author)
<br/>Aerodynamic noise produced by aircraft, wind turbines, and other objects subjected to airflow contribute to environmental noise pollution, which adversely affects human and animal health. Consequently, governments impose restrictions on aircraft and wind turbine noise levels. These restrictions can have an economic impact by limiting...
doctoral thesis 2022
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Rego, Leandro (author)
Aircraft noise levels have been significantly reducedwith the introduction of high-bypass ratio turbofan engines, particularly jet noise due to turbulence mixing. This, however, has led to engines with larger diameters and a closer coupling between them and the airframe. As a result, interactions between the exhaust jet flow and the wing give...
doctoral thesis 2022
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Romani, G. (author), Grande, E. (author), Avallone, F. (author), Ragni, D. (author), Casalino, D. (author)
This paper presents a computational study of flow incidence effects on the aeroacoustics of a propeller operating at low blade-tip Mach numbers. The numerical flow solution is obtained by using the Lattice-Boltzmann/Very Large Eddy Simulation method, while far-field noise is computed through the Ffowcs-Williams &amp; Hawkings' acoustic...
journal article 2022
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Rego, Leandro (author), Avallone, F. (author), Ragni, D. (author), Casalino, D. (author)
This paper investigates the mechanisms by which flow-permeable materials provide noise reduction in an installed jet configuration. Numerical simulations are carried out with a flat plate placed in the near field of a single-stream subsonic jet (M<sub>a</sub>=0.3 and M<sub>a</sub>=0.5). The trailing-edge region of the plate is replaced by...
journal article 2022
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Amoiridis, O. (author), Zarri, A. (author), Zamponi, R. (author), Pasco, Y. (author), Yakhina, G. (author), Christophe, J. (author), Moreau, S. (author), Schram, C. (author)
Sound emissions of an automotive engine cooling system are studied using both single-microphone directivity measurements and a rotating beamforming technique. These measurements provide reference acoustic data on such a system and some new understanding of the effect that the radiator induces on the distribution of sound sources. Indeed, the...
journal article 2022
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Hirschberg, L. (author), Bake, F. (author), Knobloch, K. (author), Hulshoff, S.J. (author), Hirschberg, A. (author)
An experimental cold-gas study of the response of a choked convergent–divergent nozzle to swirl perturbations is presented. The perturbations were obtained by means of upstream unsteady tangential injections into initially steady flows with different values of steady background swirl. The swirl perturbations induced changes in the axial mass...
journal article 2022
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Rego, Leandro (author), Avallone, F. (author), Ragni, D. (author), Casalino, D. (author), Denayer, Hervé (author)
A Helmholtz resonator with a curved cavity is studied for reducing jet-installation noise in a configuration comprised by a subsonic jet and a nearby flat plate. The face-sheet and cavity are designed with the Guess method and the impedance is verified through an experiment and a simulation of an impedance tube. Both single and double degree...
journal article 2022
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Mijjer, Jur (author)
Over the last few decades, the bypass ratio and nacelle diameter of modern turbofans have been increasing to achieve higher efficiencies. This trend has forced the underwing-mounted engines to be coupled more closely to the wing surface and the flap system, which significantly enhances the low-frequency noise, known as jet installation noise ...
master thesis 2021
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van Hoogstraten, Daan (author)
This work presents an experimental and analytical investigation of unsteady loading of a low Reynolds number propeller and its relation to aeroacoustics. The propeller is positioned at an angle of attack with respect to the freestream which causes a variation in loading along the azimuth. The propeller is operated at 4000 RPM with an advance...
master thesis 2021
document
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
document
Romani, G. (author), Grande, E. (author), Avallone, F. (author), Ragni, D. (author), Casalino, D. (author)
This paper proposes a CFD/CAA-based approach to predict the aerodynamic performances and tonal/broadband noise radiation of low-Reynolds number propellers at engineering level. Broadband self-noise prediction of low-Reynolds number propellers is particularly challenging, due to the requirement for the employed computational method to emulate...
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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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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Tamaro, Simone (author), Zamponi, R. (author), Ragni, D. (author), Teruna, C. (author), Schram, Christophe (author)
Abstract: The flow field on solid and porous airfoils subjected to turbulence shed by an upstream cylindrical rod and the corresponding far-field noise radiations are studied through particle image velocimetry (PIV) and microphone measurements, respectively. Three different Reynolds numbers based on the rod diameter are considered in a range...
journal article 2021
document
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), 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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