Instability over a Porous Liner in a Duct with Flowsapem2017.matelys.com/proceedings/Flow/000028.pdf · Instability over a Porous Liner in a Duct with Flow Yves Aurégan Laboratoire

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

materials for vibro-acoustic applications

P. BONFIGLIO, et al.

12:15 13:30 Lunch

13:30 13:50 Poster 10(charac), 48(charac), 68(charac), 9(models)

13:50 14:10 Charac 760 - Characterization of poroelastic materials through interface scattering

and propagation models

S. BOURGUIGNON, N. BOUHLEL, A. DUCLOS, J.P. GROBY

14:10 14:30 Charac 864 - Characterizing rigid frame porous materials with deterministic and

statistical inversion

M. NISKANEN, J.P. GROBY, A. DUCLOS, O. DAZEL, J.C. LE ROUX, N.

POULAIN, T. HUTTUNEN, T. LÄHIVAARA

14:30 14:50 Charac 939 - Efficient simulation of dispersion envelope of poro-elastic media J. RODENAS, F. CHEVILLOTTE, F.-X. BÉCOT, L. JAOUEN

14:50 15:20 Coffee break

15:20 15:40 Poster 30(models), 32(models), 70(models), 22(materials)

Laboratoire d’Acoustiquede l’Universté du Maine

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



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



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



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)

Sjoerd Rienstra Wave Motion, 2003 (systematic classification)

Edward Brambley and Nigel Peake Wave Motion, 2006

…



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



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)



8

Instablemode

Mode continuum

Acousticalmodes

Position of the problem

u’ v’

Unstable mode visualisation



9

What happens when, instead of locally-reacting linings,

porous bulk-reacting linings are used?

Liner = Porous material

Grazing flow

Incident wave



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 ?



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



12

Porous bulk-reacting lining

x

11 microphones

x x



13

Unstable mode visualisationParticle Image Velocimetry

(PIV)

20 mm

Laser

sheet

Liner

Camera

80 mm

20 mm

25 mm

80 mm

x

z

y

Flow

Incident wave



14




15




16

Unstable mode visualisation: Mean flow

0 20 40 60 80 1000

2

4

6

8

10

U (m/s)

y (m

m)

Mean axial velocity

x= -5 mm

x= 75 mm

Mean transverse velocity



17

Unstable mode visualisation: Fluctuating velocity

1220 Hz, u’ 1220 Hz, v’

1500 Hz, u’ 1500 Hz, v’

u’

u’

v’

v’



18

Unstable mode visualisation: Mode identification

acoustic

Hyrodynamicconvective unstable

Hyrodynamicstatic unstable



19

Unstable mode visualisation: Mode identification

Hydro convected Hydro convected

Hydro static Hydro static

Acoustic

+

+

=Total

Acoustic

+

+

=Total

u’

Measurement Measurement

v’



20

Unstable mode visualisation: Detachment of the hydrodynamic wave

50 60 70 800

5

10

x (mm)y (

mm

)

50 60 70 800

5

10

0

1

2

3

0

1

2

3

(a)

(b)

fundamental

second harmonic

axial velocity u’



21

Conclusions

Unstable convective mode can exist over a porous liner.

This mode is responsible of oscillation in the transmission coefficient in the flow direction.

These oscillations correspond to wave interference mechanism between acoustic and hydrodynamic modes

The flow through the material can lead to unsteady flow separation near the trailing end of the material.

➠ Modelisation not so easy …

Documents

Instability over a Porous Liner in a Duct with Flowsapem2017.matelys.com/proceedings/Flow/000028.pdf · Instability over a Porous Liner in a Duct with Flow Yves Aurégan Laboratoire