Searched for: subject:"aeroacoustics"
(1 - 20 of 44)

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Malgoezar, A.M.N. (author)
Humans localize sound incessantly using the ears and it proves to be important of<br/>our awareness. It can also be a cause of annoyance to the community whenever<br/>sound is in the form of noise. Due to increase of wealth, industry, technology and<br/>corresponding globalization there is a large increase of noise. Especially with the<br/...
doctoral thesis 2019
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Merino Martinez, R. (author), Sijtsma, P. (author), Snellen, M. (author), Finez, A. (author), Herold, G. (author), Malgoezar, A.M.N. (author), Pereira, A. (author), Sarradj, E. (author), Simons, D.G. (author)
Phased microphone arrays have become a well-established tool for performing aeroacoustic measurements in wind tunnels (both open-jet and closed-section), flying aircraft, and engine test beds. This paper provides a review of the most well-known and state-of-the-art acoustic imaging methods and recommendations on when to use them. Several...
journal article 2019
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Romani, G. (author), Casalino, D. (author)
The aim of this paper is to assess the accuracy, capabilities and computational performances of the Lattice-Boltzmann/Very Large Eddy Simulation Method to predict the unsteady aerodynamic loads, the rotor wake development and the noise radiation of helicopter rotors in strong Blade-Vortex Interaction conditions. The numerical flow solution is...
journal article 2019
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Merino Martinez, R. (author)
With the continuous growth in demand for air traffic and wind turbines, the noise emissions they generate are becoming an increasingly important issue. To reduce their noise levels, it is essential to obtain accurate information about all the sound sources present. Phased microphone arrays and acoustic imaging methods allow for the estimation of...
doctoral thesis 2018
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Kurelek, J.W. (author), Kotsonis, M. (author), Yarusevych, S. (author)
Transition and flow development in a separation bubble formed on an airfoil are studied experimentally. The effects of tonal and broadband acoustic excitation are considered since such acoustic emissions commonly result from airfoil self-noise and can influence flow development via a feedback loop. This interdependence is decoupled, and the...
journal article 2018
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Sinnige, T. (author)
Propellers can enable a significant reduction in energy use of future aircraft by offering a higher propulsive efficiency than turbofan engines. This is especially relevant for a new generation of (hybrid-)electric aircraft. However, the integration of propellers with the airframe remains a challenge, and leads to performance and noise penalties...
doctoral thesis 2018
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Avallone, F. (author), van der Velden, W.C.P. (author), Ragni, D. (author), Casalino, D. (author)
Trailing-edge serrations are add ons retrofitted to wind-turbine blades to mitigate turbulent boundary-layer trailing-edge noise. This manuscript studies the physical mechanisms behind the noise reduction by investigating the far-field noise and the hydrodynamic flow field. A conventional sawtooth and a combed-sawtooth trailing-edge serration...
journal article 2018
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Zhang, Xueqing (author), Sciacchitano, A. (author), Pröbsting, S. (author)
Particle image velocimetry for the experimental assessment of trailing edge noise sources has become focus of research in recent years. The present study investigates the feasibility of the noise prediction for high-lift devices based on time-resolved particle image velocimetry (PIV). The model under investigation is a NACA 0015 airfoil with...
journal article 2018
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Guariglia, Daniel (author), Rubio Carpio, A. (author), Schram, Christophe (author)
Shock-cell noise occurs in aero-engines when the nozzle exhaust is supersonic and shock-cells are present in the jet. In commercial turbofan engines, at cruise, the secondary flow is often supersonic underexpanded, with the formation of annular shock-cells in the jet and consequent onset of shock-cell noise. This paper aims at describing the...
journal article 2018
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Arce Leon, C.A. (author), Merino Martinez, R. (author), Ragni, D. (author), Avallone, F. (author), Scarano, F. (author), Pröbsting, S. (author), Snellen, M. (author), Simons, D.G. (author), Madsen, Jesper (author)
The broadband noise generated by the scattering of turbulent flow at the trailing edge of a NACA 0018 airfoil with trailing edge serrations is investigated, varying both the airfoil angle of attack and serration flap angle. Acoustic emissions from the trailing edge are measured using a microphone array. The noise level is observed to be...
journal article 2017
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Arce Leon, C.A. (author)
The flow near the surface, and the acoustic emissions of trailing edge serrations are investigated in this work. The use of this family of aerodynamic devices on airfoils is intended for the reduction of turbulent boundary layer-trailing edge noise (TBL-TE noise). This purpose has been well demonstrated in wind tunnel and numerical experiments....
doctoral thesis 2017
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Arce Leon, C.A. (author), Merino Martinez, R. (author), Pröbsting, S. (author), Ragni, D. (author), Avallone, F. (author)
The trailing edge of a NACA 0018 airfoil is modified through the attachment of serrations with different degrees of permeability. Acoustic beamforming is used to inspect the turbulent boundary layer-trailing edge noise emissions from the unmodified and serrated trailing edges. Different freestream velocities and angles of attack are investigated...
journal article 2017
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Gennaretti, Massimo (author), Bernardini, Giovanni (author), Serafini, Jacopo (author), Anobile, A. (author), Hartjes, S. (author)
This paper investigates different methodologies for the evaluation of the acoustic disturbance emitted by helicopter’s main rotors during unsteady maneuvers. Nowadays, the simulation of noise emitted by helicopters is of great interest to designers, both for the assessment of the acoustic impact of helicopter flight on communities and for the...
journal article 2017
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van der Velden, W.C.P. (author)
doctoral thesis 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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Avallone, F. (author), van der Velden, W.C.P. (author), Ragni, D. (author)
Far-field noise and flow field over a novel curved trailing-edge serration (named as iron-shaped serration) 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...
journal article 2017
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Zhang, Xueqing (author), Sciacchitano, A. (author), Pröbsting, S. (author)
The present study investigates the feasibility of high-lift devices noise prediction based on measurements of time-resolved particle image velocimetry (TR-PIV). The model under investigation is a NACA 0015 airfoil with Gurney flap with height of 6% chord length. The velocity fields around and downstream the Gurney flap are measured by PIV and...
conference paper 2016
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Arce Leon, C.A. (author), Ragni, D. (author), Pröbsting, S. (author), Scarano, F. (author), Madsen, Jesper (author)
The flow past a NACA 0018 airfoil with sawtooth trailing edge serrations has been investigated using stereoscopic particle image velocimetry (PIV). The serration flap angle and airfoil incidence are varied in order to study the effect of secondary flow establishing between the suction and pressure sides of the serrations. The flow topology...
journal article 2016
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Pröbsting, S. (author)
Noise generated aerodynamically by the airflow over a lifting surface is often of concern for applications as diverse as air and ground transportation, heating, ventilation, air-conditioning systems, and wind turbines. The thesis describes the application of advanced optical flow measurements techniques for the visualization and description of...
doctoral thesis 2015
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Pröbsting, S. (author), Serpieri, J. (author), Scarano, F. (author)
The present study investigates the mechanisms associated with tonal noise emission from a NACA 0012 aerofoil at moderate incidence (0; 1; 2 and 4 angle of attack) and with Reynolds numbers ranging from 100 000 to 270 000. Simultaneous time-resolved particle image velocimetry (PIV) of the aeroacoustic source region near the trailing edge and...
journal article 2014
Searched for: subject:"aeroacoustics"
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