Aeroacoustic Characterization of Single- and Multiscale Porous Fences
File(s)
Accepted version
Author(s)
Rodríguez-López, E
Brizzi, LE
Valeau, V
Bruce, PJK
Buxton, ORH
Type
Journal Article
Abstract
An experimental characterization of the acoustic behavior and the flowfield past several wall-mounted porous
fences is presented. Particle image velocimetry is conducted in the near field of the fences. It shows a spanwise
periodicity (associated with the periodic geometry of the grid) of regions where well-defined wakes appear as opposed
to regions with a lower mass flow rate influenced by strong recirculations. The acoustic behavior is characterized
using a microphone array enabling the spatial locationof noise sourcesto bedetermined. Broadband noise is observed
for all grids except for the fractal square grid, where a clear peak appears. The intensity of noise spectra displays
scalabilitywith Machnumber
M
6
(dipoles), and the preferentialfrequencyfor the fractal square case is shown to scale
with thefreestreamvelocity(suggestingasheddingmechanism).For certaingrids, themeanandinstantaneous spatial
locations of the noise sources also present a spanwise preferential arrangement coincident with regions where the flow
presents well-defined wakes. Regarding the intermittency of the unsteady sources, they present smaller temporal
width, separation, and spatial extent for increasing freestream velocity. However, the ratio between these quantities
seems to be constant to within 6% for different Mach numbers.
fences is presented. Particle image velocimetry is conducted in the near field of the fences. It shows a spanwise
periodicity (associated with the periodic geometry of the grid) of regions where well-defined wakes appear as opposed
to regions with a lower mass flow rate influenced by strong recirculations. The acoustic behavior is characterized
using a microphone array enabling the spatial locationof noise sourcesto bedetermined. Broadband noise is observed
for all grids except for the fractal square grid, where a clear peak appears. The intensity of noise spectra displays
scalabilitywith Machnumber
M
6
(dipoles), and the preferentialfrequencyfor the fractal square case is shown to scale
with thefreestreamvelocity(suggestingasheddingmechanism).For certaingrids, themeanandinstantaneous spatial
locations of the noise sources also present a spanwise preferential arrangement coincident with regions where the flow
presents well-defined wakes. Regarding the intermittency of the unsteady sources, they present smaller temporal
width, separation, and spatial extent for increasing freestream velocity. However, the ratio between these quantities
seems to be constant to within 6% for different Mach numbers.
Date Issued
2017-08-28
Date Acceptance
2017-07-13
Citation
AIAA Journal, 2017, 56 (1), pp.264-278
ISSN
0001-1452
Publisher
American Institute of Aeronautics and Astronautics
Start Page
264
End Page
278
Journal / Book Title
AIAA Journal
Volume
56
Issue
1
Copyright Statement
© 2017 by Eduardo Rodríguez-López. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. All requests for copying and permission to reprint should be submitted to CCC at www.copyright.com; employ the ISSN 0001-1452 (print) or 1533-385X (online) to initiate your request. See also AIAA Rights and Permissions www.aiaa.org/randp.
Sponsor
Commission of the European Communities
Grant Number
FP7 - 317269
Subjects
Science & Technology
Technology
Engineering, Aerospace
Engineering
NAVIER-STOKES EQUATIONS
AERODYNAMIC DESIGN OPTIMIZATION
DRAG MINIMIZATION
GEOMETRY PARAMETERIZATION
UNSTRUCTURED MESHES
SHAPE OPTIMIZATION
OPTIMUM DESIGN
LINEAR-SYSTEMS
FREE-FORM
ALGORITHM
0901 Aerospace Engineering
0913 Mechanical Engineering
Aerospace & Aeronautics
Publication Status
Published
Date Publish Online
2017-09-06