- document
-
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
- document
-
Yunus, F. (author), Casalino, D. (author), Avallone, F. (author), Ragni, D. (author)This paper presents a noise propagation approach based on the Gaussian beam tracing (GBT) method that accounts for multiple reflections over three-dimensional terrain topology and atmospheric refraction due to horizontal and vertical variability in wind velocity. A semi-empirical formulation is derived to reduce truncation error in the beam...journal article 2023
- document
-
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
- document
-
Fiscaletti, D. (author), Luesutthiviboon, S. (author), Avallone, F. (author), Casalino, D. (author)Streamwise fences for the reduction of the trailing-edge noise are experimentally investigated on a NACA633018 airfoil. Interchangeable trailing-edge inserts with streamwise fences of different spacing and height are tested in an anechoic wind tunnel. Far-field trailing-edge noise was measured by an array of microphone and the airfoil drag was...conference paper 2022
- document
-
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
- document
-
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
- document
-
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
- 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
-
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
- document
-
Grande, E. (author), Ragni, D. (author), Avallone, F. (author), Casalino, D. (author)This paper explains the presence and relevance of noise caused by a laminar separation bubble (LSB) on a propeller operating at low-Reynolds number. Microphone measurements of a propeller with both clean and forced boundary layer transition blades are carried out in an anechoic wind tunnel by varying the propeller advance ratio J from 0 to 0...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
-
Grande, E. (author), Ragni, D. (author), Avallone, F. (author), Casalino, D. (author)This paper explains the presence and relevance of noise caused by a laminar separation bubble (LSB) on a propeller operating at a low Reynolds number. Microphone measurements of a propeller with both clean and forced boundary-layer transition blades are carried out in an anechoic wind tunnel by varying the propeller advance ratio J from 0 to 0.6...journal article 2022
- document
-
Brandetti, L. (author), Avallone, F. (author), De Tavernier, D. (author), LeBlanc, B.P. (author), Ferreira, Carlos (author), Casalino, D. (author)Vertical-axis wind turbines have the potential to be installed nearby urban areas, where noise regulations are a constraint. Accurate modelling of the far-field noise with low-order fidelity methods is essential to account for noise early in the design phase. The challenge for the vertical-axis wind turbine is the unsteady azimuthal variation...journal article 2022
- document
-
Rego, Leandro (author), Avallone, F. (author), Ragni, D. (author), Casalino, D. (author)This paper investigates the mechanisms by which flow-permeable materials provide noise reduction in an installed jet configuration. Numerical simulations are carried out with a flat plate placed in the near field of a single-stream subsonic jet (M<sub>a</sub>=0.3 and M<sub>a</sub>=0.5). The trailing-edge region of the plate is replaced by...journal article 2022
- document
-
Yunus, F. (author), Grande, E. (author), Casalino, D. (author), Avallone, F. (author), Ragni, D. (author)A noise footprint prediction framework for propeller-driven aircraft which couples an aerodynamic model and several aeroacoustic models is presented in this study. The aerodynamic model is based on the blade element momentum theory, while the aeroacoustic models are based on a time-domain compact dipole/monopole Ffowcs-Williams and Hawking's...journal article 2022
- document
-
Measurement techniques for aeroacoustics: From aerodynamic comparisons to aeroacoustic assimilationsRagni, D. (author), Avallone, F. (author), Casalino, D. (author)Sustainability has encouraged studies focusing on lowering the aeroacoustic impact of new aerodynamically optimized mechanical systems for several applications in wind-energy, aviation, automotive and urban air-mobility. The deployment of effective noise-reduction strategies starts with a deep understanding of the underlying mechanisms of...review 2022
- document
-
Rego, Leandro (author), Avallone, F. (author), Ragni, D. (author), Casalino, D. (author), Denayer, Hervé (author)A Helmholtz resonator with a curved cavity is studied for reducing jet-installation noise in a configuration comprised by a subsonic jet and a nearby flat plate. The face-sheet and cavity are designed with the Guess method and the impedance is verified through an experiment and a simulation of an impedance tube. Both single and double degree...journal article 2022
- document
-
Casalino, D. (author), Grande, E. (author), Romani, G. (author), Ragni, D. (author), Avallone, F. (author)Experimental and numerical results of a propeller of 0.3 m diameter operated at 5000 RPM and axial velocity ranging from 0 to 20 m/s and advance ratio ranging from 0 to 0.8 are presented as a preliminary step towards the definition of a benchmark configuration for low Reynolds number propeller aeroacoustics. The corresponding rotational tip...journal article 2021
- document
-
Romani, G. (author), Grande, E. (author), Avallone, F. (author), Ragni, D. (author), Casalino, D. (author)This paper proposes a CFD/CAA-based approach to predict the aerodynamic performances and tonal/broadband noise radiation of low-Reynolds number propellers at engineering level. Broadband self-noise prediction of low-Reynolds number propellers is particularly challenging, due to the requirement for the employed computational method to emulate...journal article 2021
- 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 in aerodynamic and aeroacoustic wind-tunnel experiments. The statistical features and spectral content of the pressure fluctuations in the resulting turbulent boundary layer at the trailing edge can affect far-field noise. To elucidate this dependence, boundary...journal article 2021