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Boatto, U. (author), Bonnet, Jean-Paul (author), Avallone, F. (author), Ragni, D. (author)The design of efficient rotor blades is affected by the accuracy of aerodynamic prediction methods for load distributions and power computations. Research showed that the accuracy of BEMT-based industrial codes decreases at high inflow-speed under uniform aligned steady conditions. The identified reasons are inaccuracies in the semi-empirical...conference paper 2023
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Zoppini, G. (author), Sequeira, A.D. (author), Michelis, Theodorus (author), Ragni, D. (author), Kotsonis, M. (author)The present work details the steady and unsteady flow topology in the vicinity of an array of periodically spaced super-critical (i.e. causing flow tripping) discrete roughness elements (DRE) applied in a swept wing boundary layer. The stationary flow field is acquired by means of high-magnification dual-pulse tomographic particle tracking...conference paper 2023
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Terracol, Marc (author), Manueco, Lucas (author), Manoha, Eric (author), Avallone, F. (author), Ragni, D. (author), Rubio Carpio, A. (author)This study presents a numerical investigation of the noise mitigation effect provided by several fairings placed upstream of a simplified two-wheel landing gear. The chosen configuration is equipped with detachable elements that mimic realistic components, e.g. brakes and torque link, to include representative landing gear noise sources. Several...conference paper 2023
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do Nascimento Monteiro, F. (author), Ragni, D. (author), Avallone, F. (author), Sinnige, T. (author)A low-order numerical tool for estimating noise emissions from distributed propeller configurations is presented. The paper describes the tool's computational framework, which uses Hanson's near-field theory to calculate the thickness and loading noise components. The formulation assumes steady blade loading, but an unsteady case can be handled...conference paper 2023
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Dekker, H.N.J. (author), Tuinstra, M (author), Baars, W.J. (author), Scarano, F. (author), Ragni, D. (author)A semi-emperical model is developed, able to capture the aeropropulsive performance characteristics of Over-The-Wing propellers at incidence. The model is based on an hypothesis on the interactions of the propeller- and wing-induced flow fields. Effects of these interactions on the both the thrust and lift are written in a form in which the...conference paper 2023
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Baars, W.J. (author), Ragni, D. (author)Rotor noise comprises harmonic features, related to the blade passing frequency, as well as broadband noise. Even though acoustic spectra yield frequency-distributions of acoustic energy within pressure time series, they do not reveal phase-relations between different frequency components. The latter are of critical importance for the...conference paper 2023
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Trascinelli, L. (author), Bowen, Luke (author), Piccolo, A. (author), Zamponi, R. (author), Ragni, D. (author), Avallone, F. (author), Zhou, Beckett Y. (author), Zang, Bin (author)The present study assesses the ability to numerically predict turbulence-interaction noise of a NACA0012 airfoil with grid-generated turbulence by utilizing the Lattice Boltzmann solver PowerFLOW. Both the near-field flow characteristics and far field noise are bench-marked against an existing experimental study. The grid was chosen to match...conference paper 2023
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Zarri, Alessandro (author), Koutsoukos, P.A. (author), Avallone, F. (author), de Prenter, Frits (author), Ragni, D. (author), Casalino, D. (author)Distributed electric propulsion systems are an emerging technology with the potential of revolutionizing the design and performance of aircraft. When propellers are located in close proximity, they can be subjected to aerodynamic interactions, which affect the far-field noise. In this paper, we study an array of three co-rotating and adjacent...conference paper 2023
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Piccolo, A. (author), Zamponi, R. (author), Avallone, F. (author), Ragni, D. (author)The analytical model for leading-edge noise prediction formulated by Amiet, developed for a flat plate, relates the far-field acoustic pressure to the upstream inflow conditions, modeled by canonical turbulence spectra. The inaccurate results provided by this low-fidelity method when applied to thick airfoils has been attributed to the...conference paper 2023
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Mourão Bento, H.F. (author), VanDercreek, Colin (author), Avallone, F. (author), Ragni, D. (author), Sijtsma, P. (author), Snellen, M. (author)Aeroacoustic tests in closed wind tunnels are affected by reflections in the tunnel circuit and background noise. Reflections can be mitigated by lining the tunnel circuit. The present study investigates if lining exclusively the most accessible segment of a closed wind tunnel circuit, in particular the test section, is an approach which...conference paper 2023
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Lima Pereira, L.T. (author), Avallone, F. (author), Ragni, D. (author), Buck, Steven (author), Oerlemans, S. (author)This work proposes a semi-empirical framework to predict the noise of wind turbines with serrated trailing edge blades. The framework is employed for studying the reduction of the noise of the SWT 2.3-93 benchmark wind turbine. The framework is verified against field acoustic measurements of the real wind-turbine model and of noise reduction...conference paper 2023
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Kalyani, S.K. (author), Jaiswal, P. (author), Rendón, Jose (author), Moreau, Stéphane (author), Ragni, D. (author)The present experimental investigation focuses on a flow-field and noise characterization of a CD airfoil experiencing large flow separation and stall. Measurements are performed to investigate the effect of Reynolds number stalling noise signature of the CD airfoil. This study includes investigation of the potential interaction of wind tunnel...conference paper 2023
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- Dekker, H.N.J. (author), Tuinstra, Marthijn (author), Baars, W.J. (author), Scarano, F. (author), Ragni, D. (author) conference paper 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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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