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Bampanis, G. (author), Roger, M. (author), Ragni, D. (author), Avallone, F. (author), Teruna, C. (author)The present work is aimed at assessing leading-edge serrations as an airfoil turbulenceimpingement noise (TIN) reduction mean. It relies on extended anechoic wind-tunnel testing including far-field measurements over an observation sphere to infer the three-dimensional features of TIN, and on microphone-array measurements to extract leading-edge...conference paper 2019
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Ye, Q. (author), Avallone, F. (author), Ragni, D. (author), Choudhari, Meelan (author), Casalino, D. (author)The effects of a finite, spanwise-periodic array of cylindrical roughness elements on boundary layer transition over a NACA 0012 airfoil are investigated at a chord-based Reynolds number of 1.44×10<sup>5</sup> by using hotwire anemometry and infrared thermography. Both the number and the spanwise spacing of roughness elements in the array are...conference paper 2019
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Rego, Leandro (author), Avallone, F. (author), Ragni, D. (author), Casalino, D. (author)A numerical investigation on jet-installation noise is performed using a software based on the Lattice-Boltzmann Method. A flat plate is placed in the irrotational hydrodynamic field of the jet, i.e. outside of the plume, resulting in noise increase due to the scattering of instability waves at the plate trailing edge. The configuration adopted...conference paper 2019
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González, G. (author), Ragni, D. (author), Avallone, F. (author), Schneiders, J.F.G. (author), Casalino, D. (author), Ianiro, A. (author)The analysis of the unsteady flow field of an axisymmetric subsonic jet at Reynolds numbers between 5,000 and 20,000 and computation of its unsteady pressure field is carried out from single snapshots of tomographic PIV measurements (acquisition rate 0.8 Hz). This is achieved by a recently developed pressure-evaluation technique based upon...conference paper 2018
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Rubio Carpio, A. (author), Avallone, F. (author), Ragni, D. (author)The turbulent flow over a NACA 0018 airfoil with porous trailing edge inserts and the resulting scattered turbulent-boundary-layer trailing edge noise are studied to investigate the effect of the cross-flow through the material. The experiments are performed at a chord-based Reynolds number of 2.63×10<sup>5</sup> and an angle of attack of 0°....conference paper 2018
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Manjunath, P. (author), Avallone, F. (author), Casalino, D. (author), Ragni, D. (author), Snellen, M. (author)Acoustic liners are widely used as noise suppression devices, for example in aircraft engines. The effectiveness of the liners is measured through the impedance. In the present study, using a lattice-Boltzmann solver, the response of two liner geometries to grazing acoustic waves is examined. The two geometries have porosity equal to 0.99%...conference paper 2018
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Merino Martinez, R. (author), Sanders, Martinus P.J. (author), Caldas, Luciano C. (author), Avallone, F. (author), Ragni, D. (author), de Santana, Leandro D. (author), Snellen, M. (author), Simons, D.G. (author)Microphone arrays are useful measurement devices for estimating the location and strength of sound sources. Numerous comparative studies have been conducted regarding the performance of acoustic imaging methods in the past, but literature lacks of a systematic investigation on the role of the hardware on the measurements. This research...conference paper 2018
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Arce Leon, C.A. (author), Merino Martinez, R. (author), Ragni, D. (author), Pröbsting, S. (author), Avallone, F. (author), Singh, A. (author), Madsen, Jesper (author)Trailing edge serrations have been proven to work as a passive noise reduction device. Nevertheless, they have also previously been found to increase noise in a particular frequency range, argued in earlier research to be due to the misalignment of the serrations with the direction of the flow in the wake. It emerges as a high-frequency noise...conference paper 2017
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Merino Martinez, R. (author), van der Velden, W.C.P. (author), Avallone, F. (author), Ragni, D. (author)Trailing-edge serrations are passive noise reduction add-ons widely used in wind-turbine applications. This study presents acoustic beamforming results of microphone array measurements of a cambered airfoil (DU96-W-180) in a closed-section wind-tunnel at a Reynolds number of industrial interest. Two different serration geometries with different...conference paper 2017
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de Vries, R. (author), Sinnige, T. (author), della Corte, B. (author), Avallone, F. (author), Ragni, D. (author), Eitelberg, G. (author), Veldhuis, L.L.M. (author)<br/>conference paper 2017
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della Corte, B. (author), Sinnige, T. (author), de Vries, R. (author), Avallone, F. (author), Ragni, D. (author), Eitelberg, G. (author), Veldhuis, L.L.M. (author)<br/>conference paper 2017
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van der Velden, W.C.P. (author), Avallone, F. (author), Ragni, D. (author)The relation between the far-field noise and the flow field, in presence of serrated and combed-serrated trailing edge, is studied to explain the associated noise reduction mechanisms. Both serration geometries are retrofitted to a NACA 0018 wing. Computations are carried out by solving the fully explicit, transient, compressible Lattice...conference paper 2017
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- Avallone, F. (author), van der Velden, W.C.P. (author), Merino Martinez, R. (author), Ragni, D. (author) conference paper 2017
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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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- Merino Martinez, R. (author), Rubio Carpio, A. (author), Avallone, F. (author), Ragni, D. (author), Snellen, M. (author), van der Zwaag, S. (author) conference paper 2017
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Avallone, F. (author), Correale, G. (author)An experimental investigation was conducted on the effective efficiency of a nanosecond Dielectric Barrier Discharge (ns-DBD) plasma actuator. Back-current shunt technique and infrared thermography measurements were carried out at the same time on an upside-down flat plate in a quiescent environment. The only investigated parameter was thickness...conference paper 2015
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Avallone, F. (author), Ragni, D. (author), Schrijer, F.F.J. (author), Scarano, F. (author), Cardone, G. (author)In this study, the mean flow organization in the symmetry plane of the recirculation region ahead of a cylindrical roughness element immersed in an incoming laminar boundary layer at Mach number equal to 6.5 is investigated. The flow topology is inspected with planar particle image velocimetry (PIV), InfraRed (IR) Thermography and Schlieren flow...conference paper 2015
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Crispo, C.M. (author), Greco, C.S. (author), Avallone, F. (author), Cardone, G. (author)Abstract.conference paper 2015
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- Kleiberg, T. (author), Fu, B. (author), Kuipers, F.A. (author), Avallone, S. (author), Quoitin, B. (author), Van Mieghem, P. (author) conference paper 2008
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- Avallone, S. (author), Kuipers, F. (author), Ventre, G. (author), Van Mieghem, P. (author) conference paper 2006