Instability over a Porous Liner in a Duct with Flow Yves Aurégan Laboratoire d'Acoustique de l'Université du Mans CNRS, Le Mans Université Laboratoire d’Acoustique de l’Universté du Maine 5 th SAPEM Symposium on the Acoustics of Poro-Elastic Materials December 6-7-8, 2017 LE MANS, FRANCE presented by Joachim Golliard
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Instability over a Porous Liner in a Duct with Flow
Yves AuréganLaboratoire d'Acoustique de l'Université du Mans
CNRS, Le Mans Université
Tuesday December 5th
17:00 18:00 Welcome of participants
18:00 20:00 Visit of Le Mans circuit
20:00 21:00 Dinner
Wednesday December 6th
08:00 08:30 Welcome of participants
08:30 09:00 Opening ceremony
Session: Characterisation of Porous M aterials
09:00 09:45 Keynote LecturePhotoacoustic determination of mechanical properties at microstructure
level
CHRIST GLORIEUX (KUL, Belgium)
09:45 10:05 Charac 126 - Laboratory and In Situ Sound Absorption Measurement under a
Synthetized Diffuse Acoustic Field: a Case Study on Five Materials
O. ROBIN, C.K. AMEDIN, A. BERRY, N. ATALLA, O. DOUTRES, F. SGARD
10:05 10:25 Charac 217 - Vibration damping properties of porous materials L. ROULEAU, A. GUINAULT, J.-F. DEU
10:25 10:55 Coffee break
10:55 11:15 Charac 312 - Micro- to Macro-scale Investigations of Anisotropy and Local
Boundary Stiffness Variations in Open-cell Lightweight Foams
P. GORANSSON, J. CUENCA, E. LUNDBERG, L. MANZARI
11:15 11:35 Charac 4
62 - SLaTCoW (Spatial LAplace Transform for COmplex Wavenumber
recovery) method for frequency / complex wavenumber dispersion
relation recovery
A. GESLAIN, L. SCHWAN, J.-P. GROBY, V. ROMERO-GARCIA, S. RAETZ, A.
DUCLOS, N. BOECHLER
11:35 11:55 Charac 535 - Elastic characterization of a porous layer in a sandwich structure L. LEI, J.D. CHAZOT, N. DAUCHEZ
11:55 12:15 Charac 663 - Round Robin test on elastic properties of poro- and viscoelastic
5th SAPEMSymposium on the Acoustics of Poro-Elastic MaterialsDecember 6-7-8, 2017LE MANS, FRANCE
presented by Joachim Golliard
Instability over a Porous Line in a Duct with Flow Y. Aurégan (presented by J. Golliard)
5th SAPEMDecember 2017, Le Mans, France
2
Position of the problem (Not so new)
0
Attenuation(dB/m)
M=0
M=0.12
Negative attenuation= Amplification
Instability over a Porous Line in a Duct with Flow Y. Aurégan (presented by J. Golliard)
5th SAPEMDecember 2017, Le Mans, France
3
Position of the problem (experimental amplification)
Brandes and RonnebergerAIAA Conference, Berlin, 1995
4000
M=0.26
M=0
2000 30000.001
0.01
0.1
1
10Transmission T+
Frequency (Hz)
0.14
0.15
0.16
0.17
2000 3000 4000
Pressure drop
Frequency (Hz)p+
R+ p+ T+ p+M
Amplification
Instability over a Porous Line in a Duct with Flow Y. Aurégan (presented by J. Golliard)
5th SAPEMDecember 2017, Le Mans, France
4
Position of the problem (experimental amplification)
Size of pores: 1× 1×65 mm400 channels/inch2
H=15 mm
L=100 mm0 500 1000 1500 2000 2500 3000
10-3
10-2-
10-1
1
frequency (Hz)
abs(
T+)
M=0M=0.1M=0.2M=0.3
p+ T+ p+
Amplification
Y. Aurégan and M. LerouxExperimental evidence of an instability over an impedance wall in a duct with flowJournal of Sound and Vibration Vol: 317 Pages: 432–439 2008
Instability over a Porous Line in a Duct with Flow Y. Aurégan (presented by J. Golliard)
5th SAPEMDecember 2017, Le Mans, France
5
Position of the problem
Some theoretical references:
Brian Tester J. Sound and Vib., 1973 ( ”strange modes” )
Börje Nilsson and Olle Brander J. Inst. Maths Applics, 1980 (amplification in bulk-reacting lining)
Instability over a Porous Line in a Duct with Flow Y. Aurégan (presented by J. Golliard)
5th SAPEMDecember 2017, Le Mans, France
6
Position of the problemParticle Image Velocimetry
(PIV)Unstable mode visualisation
Laser
sheet
Liner
Camera
80 mm
20 mm
25 mm
80 mm
x
z
y
Flow
Incident wave
Instability over a Porous Line in a Duct with Flow Y. Aurégan (presented by J. Golliard)
5th SAPEMDecember 2017, Le Mans, France
7
Position of the problem Unstable mode visualisation
v (m/s)
0
20
-20
LDV measurements
u (m/s)100
0
u=U+ut+u’
U
u’
ut
David Marx, Yves Aurégan, Hélène Bailliet, Jean-Christophe ValièrePIV and LDV evidence of hydrodynamic instability over a liner in a duct with flowJournal of Sound and Vibration (2010)
Instability over a Porous Line in a Duct with Flow Y. Aurégan (presented by J. Golliard)
5th SAPEMDecember 2017, Le Mans, France
8
Instablemode
Mode continuum
Acousticalmodes
Position of the problem
u’ v’
Unstable mode visualisation
Instability over a Porous Line in a Duct with Flow Y. Aurégan (presented by J. Golliard)
5th SAPEMDecember 2017, Le Mans, France
9
What happens when, instead of locally-reacting linings,
porous bulk-reacting linings are used?
Liner = Porous material
Grazing flow
Incident wave
Instability over a Porous Line in a Duct with Flow Y. Aurégan (presented by J. Golliard)
5th SAPEMDecember 2017, Le Mans, France
10
Porous bulk-reacting lining
Melamine foam samples used for the testing
0 1000 2000 3000 40000
0.2
0.4
0.6
0.8
Frequency (Hz)
|T+|
M=0.2
M=0
First experiments with Melamine foam
Skeleton vibrations ?
Hydrodynamic instability ?
Instability over a Porous Line in a Duct with Flow Y. Aurégan (presented by J. Golliard)
5th SAPEMDecember 2017, Le Mans, France
11
0 500 1000 1500 2000 2500 30000
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Frequency (Hz)
|T+|
M=0
M=0.2
M=0.3
Porous bulk-reacting liningNew experiments with metallic foam
Skeleton vibrations
Hydrodynamic instability
metallic foam RECEMAT
RCMPL-NC-4753.05pores : 0.4 mm
Instability over a Porous Line in a Duct with Flow Y. Aurégan (presented by J. Golliard)
5th SAPEMDecember 2017, Le Mans, France
12
Porous bulk-reacting lining
x
11 microphones
x x
Instability over a Porous Line in a Duct with Flow Y. Aurégan (presented by J. Golliard)