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@ARTICLE{Koh:858007,
author = {Koh, Seong Ryong and Meinke, Matthias and Schröder,
Wolfgang},
title = {{N}umerical analysis of the impact of permeability on
trailing-edge noise},
journal = {Journal of sound and vibration},
volume = {421},
issn = {0022-460X},
address = {London},
publisher = {Academic Press},
reportid = {FZJ-2018-06951},
pages = {348 - 376},
year = {2018},
abstract = {The impact of porous surfaces on the near-wall turbulent
structures and the generated trailing-edge noise is analyzed
for several trailing-edge shapes of finite thickness using a
high resolution large-eddy simulation (LES)/computational
aeroacoustics (CAA) method. The porous surface of the
trailing edge is defined by the porosity and the viscous
permeability determined by the solution of a turbulent flat
plate boundary layer at a Reynolds number 1280 based on the
displacement thickness in the inflow cross section. The
volume-averaged approach for the homogeneous porous medium
shows that the porous impedance scales linearly with the
porosity and exponentially with the mean structure size of a
porous medium. The drag induced by the porous surface
changes the friction velocity and the permeability Reynolds
number which determines the porous impedance scaled by . The
trailing-edge noise is analyzed for three solid and three
porous trailing edges. The effect of a finite span is
investigated by the spanwise correlation model based on the
measured coherence distribution. The acoustic prediction
shows a good agreement with measurements of the broadband
spectrum and the strong tone generated by a finite
trailing-edge thickness. The pressure gradient inside the
porous media is redistributed by the Darcy drag defined by
the viscous permeability and the porosity. The mean pressure
increases in the upstream direction inside the porous medium
such that the flow acceleration involved in the acoustic
generation is reduced inside the porous medium. The noise
reduction by a porous medium reaches 11 dB for the
trailing-edge shape which possesses a sharp corner for the
solid surface. The porous surface applied to a semi-circular
trailing edge achieves a 4 dB noise reduction. The
directivity pattern for individual components of the
acoustic spectrum shows that the massive noise reduction is
determined at the tone. Enhanced wave diffraction by the
thick flat plate changes the directivity pattern in the high
frequency range.},
ddc = {530},
pnm = {899 - ohne Topic (POF3-899)},
pid = {G:(DE-HGF)POF3-899},
typ = {PUB:(DE-HGF)16},
doi = {10.1016/j.jsv.2018.02.017},
url = {https://juser.fz-juelich.de/record/858007},
}