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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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Yunus, F. (author), Casalino, D. (author), Avallone, F. (author), Ragni, D. (author)Efficient calculation of urban air mobility noise footprint in a vertiport environment, considering acoustic effects of various designs, operational conditions, and environmental factors, is essential to limit the noise impact on the community at an early stage. To this purpose, the computationally efficient low-fidelity approach presented by...journal article 2023
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Arcondoulis, E.J.G. (author), Liu, Y. (author), Ragni, D. (author), Avallone, F. (author), Rubio Carpio, A. (author), Sedaghatizadeh, N. (author), Yang, Y. (author), Li, Z. (author)Vortex shedding in the wake of a cylinder in uniform flow can be suppressed via the application of a porous coating; however, the suppression mechanism is not fully understood. The internal flow field of a porous coated cylinder (PCC) can provide a deeper understanding of how the flow within the porous medium affects the wake development. A...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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Dekker, H.N.J. (author), Baars, W.J. (author), Scarano, F. (author), Tuinstra, Marthijn (author), Ragni, D. (author)The unsteady flow behaviour of two side-by-side rotors in ground proximity is experimentally investigated. The rotors induce a velocity distribution interacting with the ground causing the radial expansion of the rotor wakes. In between the rotors, an interaction of the two wakes takes place, resulting in an upward flow similar to a fountain....journal article 2023
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Gutiérrez, R. (author), Zamponi, R. (author), Ragni, D. (author), Llorente, Elena (author), Aranguren, Patricia (author)Modern wind turbines employ thick airfoils in the outer region of the blade with strong adverse pressure gradients and high sensitivity to flow separation, which can be anticipated by leading-edge roughness. However, Reynolds average Navier-Stokes simulations currently overpredict the Reynolds shear stresses near the surface, and the flow...journal article 2023
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Meloni, S. (author), de Paola, E. (author), Grande, E. (author), Ragni, D. (author), Stoica, L. G. (author), Di Marco, A. (author), Camussi, R. (author)Propeller noise generally exhibits a rich mixture of tonal and broadband components related to different physical mechanisms. Specifically, the tones are characterized by having deterministic and persistent characteristics, while the broadband counterpart has random behaviour. The separation is essential for the experimenters as they provide...journal article 2023
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Luesutthiviboon, S. (author), Meirelles Pereira, L. (author), Ragni, D. (author), Avallone, F. (author), Snellen, M. (author)Correction Notice The authors would like to provide the following corrections and clarifications to the article titled “Aeroacoustic Benchmarking of Trailing-edge Noise from a NACA 633–018 Airfoil with Trailing-edge Serrations” which has been published in the AIAA Journal Vol. 61, No. 1, and can be accessed online via https://doi.org/10.2514...journal article 2023
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Zoppini, G. (author), Ragni, D. (author), Kotsonis, M. (author)The application of an isolated roughness element in the laminar boundary layer developing on the surface of a wing, introduces flow instabilities that eventually lead to the breakdown of the laminar flow structures and the formation of a turbulent wedge. The present work, investigates the instabilities and transition process initiated by an...conference paper 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 & Hawkings' acoustic...journal article 2022
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Grande, E. (author), Romani, G. (author), Ragni, D. (author), Avallone, F. (author), Casalino, D. (author)This paper presents an experimental investigation of a propeller operating at low Reynolds numbers and provides insights into the role of aerodynamic flow features on both propeller performances and noise generation. A propeller operating at a tip Reynolds number regime of 4.3 × 10<sup>4</sup> − 4.38 × 10<sup>4</sup> is tested in an anechoic...journal article 2022
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Teruna, C. (author), Rego, Leandro (author), Casalino, D. (author), Ragni, D. (author), Avallone, F. (author)This manuscript presents the application of a recently developed noise reduction technology, constituted by poro-serrated stator blades on a full-scale aircraft model, in order to reduce rotor-stator interaction noise in the fan stage. This study was carried out using the commercial lattice Boltzmann solver 3DS-SIMULIA PowerFLOW. The simulation...journal article 2022
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Teruna, C. (author), Rego, Leandro (author), Casalino, D. (author), Ragni, D. (author), Avallone, F. (author)High-fidelity numerical simulations have been performed to investigate the noise reduction capability of porous leading-edge treatments for mitigating rotor-stator interaction noise in a full-scale aircraft model. The aircraft model consists of the NASA High-Lift Common Research Model (HL-CRM) airframe combined with an up-scaled Source...conference paper 2022
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Zamponi, R. (author), Avallone, F. (author), Ragni, D. (author), van der Zwaag, S. (author)Coating a circular cylinder with porous materials constitutes an effective passive strategy for reducing the flow-induced noise linked to the vortex shedding. Despite the number of investigations in the last decade, the noise-mitigation mechanisms associated with this technique remain unclear. The present research aims to clarify the role played...conference paper 2022
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Vergés i Plaza, G. (author), Fischer, Andreas (author), Lylloff, Oliver (author), Bak, Christian (author), Olsen, Anders S. (author), Luesutthiviboon, S. (author), Lima Pereira, L.T. (author), Ragni, D. (author), Avallone, F. (author)An experimental aero-acoustic characterisation of the NACA 63 <sub>3</sub>-018 airfoil is presented in this study, featuring trailing-edge noise emissions with and without serrations. Measurements have been carried out for a chord-based Reynolds number range between 0.18 × 10 <sup>6</sup> and 4.8 × 10 <sup>6</sup> . Two airfoil models with...conference paper 2022
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Arcondoulis, Elias J. G. (author), Liu, Yu (author), Yang, Yannian (author), Ragni, D. (author), Rubio Carpio, A. (author), Avallone, F. (author)The application of a porous coating to a cylinder can significantly reduce the vortex shedding tone when placed in a uniform flow. The mechanism of how this porous media attenuates vortex shedding has been studied more in recent years yet it is still not fully understood. Typical porous materials within a certain range of porosity and airflow...conference paper 2022
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Meloni, S (author), de Paola, E. (author), Grande, E. (author), Ragni, D. (author), Stoica, L. G. (author), Di Marco, A. (author), Camussi, R. (author)The present study reports a novel wavelet-based method aimed at separating the noise emitted by a single propeller into two contributions, tonal and broadband. An assessment using two different experimental investigations of propellers operating in diverse configurations is presented. The first experiment focuses upon near-field polar microphone...conference paper 2022
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Bennett, Gareth J. (author), Lai, Jiang (author), O'Brien, Gordon C. (author), Ragni, D. (author), Avallone, F. (author), Rubio Carpio, A. (author), Pott-Pollenske, Michael (author)This paper examines the use of both flow control and passive low noise technologies to reduce the aerodynamic noise radiated from a modified LAGOON landing gear, as tested in the EU funded H2020 collaborative research project: INVENTOR, InnoVative dEsign of iNstalled airframe componenTs for aircraft nOise Reduction. At approach to landing,...conference paper 2022
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Kalyani, S.K. (author), Moreau, Stéphane (author), Ragni, D. (author)The present experimental investigation in the anechoic wind tunnel of university of Sherbrooke focuses on the flow-field and noise characterization of a Controlled Diffusion (CD) airfoil, with the flow transitioning from an attached boundary layer at 15◦ incidence to a completely detached one (deep stall) at 22◦ incidence. Simultaneous unsteady...conference paper 2022
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Yunus, F. (author), Casalino, D. (author), Avallone, F. (author), Ragni, D. (author)This work presents a novel noise propagation approach based on the Gaussian Beam Tracing (GBT) method that accounts for complex source directivity, weather conditions, and irregular ground topology for the evaluation of the noise footprint. The approach takes a precomputed noise sphere as input and propagates the acoustic pressure...conference paper 2022