- document
-
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
- document
-
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
- document
-
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
- document
-
Rego, Leandro (author), Zamponi, R. (author), Ragni, D. (author), Avallone, F. (author), Casalino, D. (author), Cruellas Bordes, M. (author)An experimental investigation on jet-installation noise reduction with permeable flaps on an aircraft half-model is performed, focusing on the effects on the noise levels as well as on the aerodynamic properties of the model (lift and drag forces). A nozzle with an exit diameter = 113 mm is included for generating a single-stream jet flow in...conference paper 2022
- document
-
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
- document
-
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
- document
-
Gondrum, M. (author), Niemöller, A. (author), Meinke, M. (author), Schröder, W. (author), Rubio Carpio, A. (author), Ragni, D. (author), Avallone, F. (author)The time resolved flow and acoustic fields around a simplified two-wheel nose landing gear configuration featuring brakes, torque link, and a detachable fairing are investigated by numerical and experimental means. The flow field is computed by a lattice Boltzmann method with a collision step based on countable cumulants. Numerical near field...conference paper 2022
- document
-
Nederlof, R. (author), Ragni, D. (author), Sinnige, T. (author)The use of electric motors enables a more flexible operation of propellers compared to conventional combustion engines. One possible benefit is the easier operation at negative thrust, which could be beneficial for energy recovery, control purposes, and lower noise through steeper descents. By changing the pitch of the propellers and actively...conference paper 2022
- document
-
Zoppini, G. (author), Ragni, D. (author), Kotsonis, M. (author)An experimental parametric study of the effect of discrete roughness elements (DRE) on the development and breakdown of stationary crossflow instability on a swept wing is presented. A systematic investigation of the receptivity to various elements height and chord locations is carried out in a crossflow dominated flow. The flow is globally and...conference paper 2021
- document
-
Teruna, C. (author), Avallone, F. (author), Ragni, D. (author), Casalino, D. (author), Rubio Carpio, A. (author)This manuscript presents a numerical investigation of an open-cell 3D-printed perme-able/porous insert used to reduce turbulent boundary layer-trailing edge (TBL-TE) noise. The matrix topology of the insert resembles the lattice of diamond atoms, and thus, it is also referred to as the diamond trailing edge (TE). The porous insert replaces...conference paper 2021
- document
-
Arcondoulis, Elias J. G. (author), Liu, Yu (author), Yang, Yannian (author), Ragni, D. (author), Rubio Carpio, A. (author), Avallone, F. (author)View Video Presentation: https://doi-org.tudelft.idm.oclc.org/10.2514/6.2021-2226.vid<br/><br/>The mechanisms responsible for vortex shedding reduction, due to the application of a porous coating to a smooth cylinder placed in uniform flow, are still uncertain despite several numerical and experimental studies. To help understand these...conference paper 2021
- document
-
Zamponi, R. (author), Schram, C (author), Moreau, S. (author), Ragni, D. (author)View Video Presentation: https://doi-org.tudelft.idm.oclc.org/10.2514/6.2021-2289.vid<br/><br/>A possible strategy for the reduction of the aeroacoustic noise generated by turbulence interacting with a wing profile, also referred to as leading-edge noise, is represented by the implementation of a porous medium in the structure of the airfoil....conference paper 2021
- document
-
Lima Pereira, L.T. (author), Avallone, F. (author), Ragni, D. (author)iew Video Presentation: https://doi-org.tudelft.idm.oclc.org/10.2514/6.2021-2179.vid<br/><br/>The unsteady surface pressure fluctuations over trailing-edge serrations retrofitted to the benchmark NACA 633-018 profile are experimentally measured. Miniaturized unsteady pressure transducers installed on the serration surface are used to describe...conference paper 2021
- document
-
VanDercreek, Colin (author), Merino Martinez, R. (author), Snellen, M. (author), Ragni, D. (author), Simons, D.G. (author)This paper analyses the influence of microphone cavity geometry on beamforming measurements with a turbulent boundary layer present on the microphone array. A 16- microphone array was tested in the anechoic open-jet wind tunnel of the Delft University of Technology. The array was placed on a flat plate mounted flush with the exit nozzle of the...conference paper 2020
- document
-
Avallone, F. (author), Manjunath, P. (author), Ragni, D. (author), Casalino, D. (author)A lattice-Boltzmann Very Large Eddy simulation of a multi-orifice acoustic liner, grazed by a turbulent flow at Mach number equal to 0:3 and a planar acoustic wave with amplitude equal to 130 dB and frequency equal to 1800 Hz, is carried out. The geometry of the liner replicates the experiments carried out in the Grazing Flow Impedance Tube ...conference paper 2019
- document
-
Raiola, Marco (author), Ragni, D. (author)The present study proposes a data-driven strategy to extract the dynamics of wave-packets from low-speed velocity field measurements. The flow field under study is a subsonic turbulent round jet at Re = 33000, measured over a 20-nozzle-diameters domain in the axial direction using low-repetition-rate planar Particle Image Velocimetry. The...conference paper 2019
- document
-
Avallone, F. (author), Casalino, D. (author), Ragni, D. (author)A computational study of two Diffuser-Augmented Wind Turbines (DAWTs) is carried out to investigate both the hydrodynamic flow field and the far-field noise. The two configurations differ for the tip-clearance ratio, defined as the ratio between the tip clearance and the rotor radius. The DonQi® wind turbine, a three blades ducted rotor, is...conference paper 2019
- document
-
VanDercreek, Colin (author), Manjunath, P. (author), Ragni, D. (author), Snellen, M. (author)This study investigated how embedding microphones in different cavity geometries reduce the measured turbulent boundary layer pressure fluctuations at the microphones. The cavity geometries were systematically varied using a design of experiments (DOE) methodology. This approach tested different cavity depths, diameters, chamfers, and opening...conference paper 2019
- document
-
de Vries, R. (author), van Arnhem, N. (author), Avallone, F. (author), Ragni, D. (author), Vos, Roelof (author), Eitelberg, G. (author), Veldhuis, L.L.M. (author)This experimental study focuses on the aerodynamic interaction effects that occur between an over-the-wing (OTW) propeller and a wing boundary-layer. An OTW propeller is positioned above the hinge-line of a wing featuring a plain flap. The measurements are carried out with and without axial pressure gradients by deflecting the flap and by...conference paper 2019
- document
-
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 Boundary Layer Ingestion (BLI) embedded propulsion systems. Such engine configurations can suffer from inlet flow distortions and ingestion of turbulence at the fan plane with consequent impact on both broadband and tonal fan...conference paper 2019