- document
- Avallone, F. (author), van der Velden, W.C.P. (author), Merino Martinez, R. (author), Ragni, D. (author) conference paper 2017
- document
-
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
- document
- 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
- document
-
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
- document
-
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
- document
-
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
- document
-
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
- document
-
Dighe, V.V. (author), Suri, Dhruv (author), Avallone, F. (author), van Bussel, G.J.W. (author)Ducted Wind Turbines (DWTs) are used for energy harvesting in urban areas where the flow is non-uniform in comparison to the free-field because of the presence of buildings or other surface discontinuities. For this reason, the aerodynamic performance and far-field noise of DWTs in yawed inflow conditions must be characterized. Both the...conference paper 2020
- document
-
Goyal, J. (author), Sinnige, T. (author), Avallone, F. (author), Ferreira, Carlos (author)Regenerative propellers offer many potential benefits such as improved maneuverability, reduced landing run, and decreased community noise, besides the potential to reduce energy consumption by recovering energy during descent and landing. Since the blade loading in regenerative mode will be opposite to that in the conventional propulsive mode,...conference paper 2021
- document
-
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
- document
-
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
- 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
-
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
- document
-
Rego, Leandro (author), Avallone, F. (author), Ragni, D. (author), Casalino, D. (author), van der Velden, Wouter (author)An investigation of the effects of free-stream on jet-installation noise is performed using a numerical solver based on the lattice-Boltzmann method. In order to simulate a realistic configuration, a high-lift wing comprised by a main element and a deployed flap (MD30P30N) is placed in the vicinity of a dual-stream engine (GE90-94B). The engine...conference paper 2019
- document
-
Rubio Carpio, A. (author), Avallone, F. (author), Ragni, D. (author), Snellen, M. (author), van der Zwaag, S. (author)Turbulent boundary layer trailing-edge noise scattered by a NACA0018 airfoil equipped with 3D printed perforated trailing-edge inserts, i.e. with straight cylindrical channels connecting the two sides of the airfoil, is investigated. The inserts have different permeability in order to assess the effect of this property on broadband noise...conference paper 2019
- document
-
Teruna, C. (author), Manegar, F.A. (author), Avallone, F. (author), Casalino, D. (author), Ragni, D. (author), Rubio Carpio, A. (author), Carolus, Thomas (author)This manuscript presents a numerical investigation of the turbulent boundary layer-trailing edge (TBL-TE) noise reduction with an open-cell porous material. The implementation of the porous media is verified by emulating a facility for characterizing the flow resistivity of the porous material. Subsequently, the porous media is applied on the...conference paper 2019
- document
-
Arcondoulis, Elias J. G. (author), Ragni, D. (author), Rubio Carpio, A. (author), Avallone, F. (author), Liu, Yu (author), Yang, Yannian (author), Li, Zhiyong (author)Porous coated cylinders have been shown to reduce the vortex shedding tone and broadband noise of a bare cylinder placed in uniform flow within specific Reynolds number regimes. The processes by which the vortex shedding and thus tone suppression take place are still uncertain despite numerous numerical and experimental studies. It is understood...conference paper 2019
- document
-
Ye, Q. (author), Avallone, F. (author), Ragni, D. (author), Choudhari, Meelan (author), Casalino, D. (author)Surface roughness elements are often used to force laminar to turbulent transition during aerodynamic and aeroacoustic experiments in wind tunnels. The statistical features and frequency content of the forced turbulent boundary layer can influence the far-field trailing edge noise. To study this dependence, boundary layer transition induced by...conference paper 2019
- document
-
VanDercreek, Colin (author), Sijtsma, P. (author), Snellen, M. (author), Ragni, D. (author), Avallone, F. (author), Simons, D.G. (author)A mathematical model is proposed that evaluates acoustic propagation of turbulent boundary layer waves on top of a cavity enclosing a microphone. The goal is to optimize these cavity geometries to improve the signal-to-noise ratio of acoustic measurements. This model predicts the attenuation of the turbulent boundary layer fluctuations...conference paper 2019