Shear-layer acoustic radiation in an excited subsonic jet: experimental study

Vincent Fleury; Christophe Bailly; Daniel Juvé

doi:10.1016/j.crme.2005.09.003

Shear-layer acoustic radiation in an excited subsonic jet: experimental study

Presented by: Geneviève Comte-Bellot

Vincent Fleury ¹; Christophe Bailly ¹ ; Daniel Juvé ¹

¹ Laboratoire de mécanique des fluides et d'acoustique, UMR CNRS 5509 & École centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully cedex, France

Comptes Rendus. Mécanique, Volume 333 (2005) no. 10, pp. 746-753.

Abstract
Résumé

The subharmonic acoustic radiation of a tone excited subsonic jet shear-layer has been investigated experimentally. Two jet velocities $U_{j} = 20 m \cdot s^{−1}$ and $U_{j} = 40 m \cdot s^{−1}$ were studied. For $U_{j} = 20 m \cdot s^{−1}$ , the natural boundary-layer at the nozzle exit is laminar. When the perturbation is applied, the fluctuations of the first and the second subharmonics of the excitation frequency are detected in the shear-layer. In addition, the first subharmonic near pressure field along the spreading jet is constituted of two strong maxima of sinusoidal shape. The far-field directivity pattern displays two lobes separated by an extinction angle $θ^{⋆}$ at around 85° from the jet axis. These observations follow the results of Bridges about the vortex pairing noise. On the other hand, for $U_{j} = 40 m \cdot s^{−1}$ , the initial boundary-layer is transitional and only the first subharmonic is observed in the presence of the excitation. The near pressure field is of Gaussian shape in the jet periphery and the acoustic far-field is superdirective as observed by Laufer and Yen. The state of the initial shear-layer seems to be the key feature to distinguish these two different radiation patterns.

Le rayonnement acoustique sous-harmonique de la couche de cisaillement d'un jet subsonique excité tonalement a été étudié pour deux vitesses de jet, $U_{j} = 20 m \cdot s^{−1}$ et $U_{j} = 40 m \cdot s^{−1}$ . Pour $U_{j} = 20 m \cdot s^{−1}$ , la couche limite naturelle en sortie de buse est laminaire. En présence du forçage, les fluctuations du premier et du second sous-harmonique de la fréquence de l'excitation sont détectées dans la couche de cisaillement. Par ailleurs, le champ proche du premier sous-harmonique de la pression mesuré le long du jet est constitué de deux maxima de forme sinusoïdale. Le diagramme de directivité en champ lointain possède deux lobes séparés par un angle d'extinction $θ^{⋆}$ autour de 85° de l'axe du jet. Ces observations sont en accord avec les résultats de Bridges concernant le bruit d'appariement tourbillonnaire. En revanche, pour $U_{j} = 40 m \cdot s^{−1}$ , la couche limite initiale est transitionnelle et seul le premier sous-harmonique est observé lorsque l'excitation est utilisée. Dans ce cas, le champ de pression proche en périphérie du jet est de forme gaussienne et le champ acoustique lointain est superdirectif, comme observé par Laufer et Yen. L'état initial de la couche de cisaillement semble être le facteur déterminant pour distinguer ces deux rayonnements très différents.

Received: 2005-07-28
Accepted: 2005-08-30
Published online: 2005-10-01

DOI: 10.1016/j.crme.2005.09.003

Keywords: Fluid mechanics, Excited jet, Subharmonic, Pairing noise, Superdirective radiation
Mots-clés : Mécanique des fluides, Jet excité, Sous-harmonique, Bruit d'appariement, Rayonnement superdirectif

Author's affiliations:

Vincent Fleury ¹; Christophe Bailly ¹; Daniel Juvé ¹

¹ Laboratoire de mécanique des fluides et d'acoustique, UMR CNRS 5509 & École centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully cedex, France

@article{CRMECA_2005__333_10_746_0,
     author = {Vincent Fleury and Christophe Bailly and Daniel Juv\'e},
     title = {Shear-layer acoustic radiation in an excited subsonic jet: experimental study},
     journal = {Comptes Rendus. M\'ecanique},
     pages = {746--753},
     publisher = {Elsevier},
     volume = {333},
     number = {10},
     year = {2005},
     doi = {10.1016/j.crme.2005.09.003},
     language = {en},
}

TY  - JOUR
AU  - Vincent Fleury
AU  - Christophe Bailly
AU  - Daniel Juvé
TI  - Shear-layer acoustic radiation in an excited subsonic jet: experimental study
JO  - Comptes Rendus. Mécanique
PY  - 2005
SP  - 746
EP  - 753
VL  - 333
IS  - 10
PB  - Elsevier
DO  - 10.1016/j.crme.2005.09.003
LA  - en
ID  - CRMECA_2005__333_10_746_0
ER  -

%0 Journal Article
%A Vincent Fleury
%A Christophe Bailly
%A Daniel Juvé
%T Shear-layer acoustic radiation in an excited subsonic jet: experimental study
%J Comptes Rendus. Mécanique
%D 2005
%P 746-753
%V 333
%N 10
%I Elsevier
%R 10.1016/j.crme.2005.09.003
%G en
%F CRMECA_2005__333_10_746_0

Vincent Fleury; Christophe Bailly; Daniel Juvé. Shear-layer acoustic radiation in an excited subsonic jet: experimental study. Comptes Rendus. Mécanique, Volume 333 (2005) no. 10, pp. 746-753. doi : 10.1016/j.crme.2005.09.003. https://comptes-rendus.academie-sciences.fr/mecanique/articles/10.1016/j.crme.2005.09.003/

References
Cited by

[1] V. Kibens Discrete noise spectrum generated by an acoustically excited jet, AIAA J., Volume 18 (1980) no. 4, pp. 434-441

[2] J.E. Bridges, Application of coherent structure and vortex sound theories to jet noise, Ph.D. Dissertation, University of Houston, 1990

[3] J. Laufer; T.-C. Yen Noise generation by a low-Mach-number jet, J. Fluid Mech., Volume 134 (1983), pp. 1-31

[4] D.G. Crighton; P. Huerre Shear-layer fluctuating pressure and superdirective acoustic sources, J. Fluid Mech., Volume 220 (1990), pp. 355-368

[5] C.-M. Ho; L.-S. Huang Subharmonics and vortex merging in mixing layers, J. Fluid Mech., Volume 119 (1982), pp. 443-473

[6] A.K.M.F. Hussain; K.B.M. Zaman Vortex pairing in a circular jet under controlled excitation. Part 2. Coherent structure dynamics, J. Fluid Mech., Volume 101 (1980), pp. 493-544

[7] C.K.W. Tam; D.E. Burton Sound generated by instability waves of supersonic flows. Part 2, axisymmetric jets, J. Fluid Mech., Volume 138 (1984), pp. 273-295

[8] C.K.W. Tam Supersonic jet noise, Annu. Rev. Fluid Mech., Volume 27 (1995), pp. 17-43

[9] A.K.M.F. Hussain Coherent structures and turbulence, J. Fluid Mech., Volume 173 (1986), pp. 303-356

[10] C. Bogey; C. Bailly; D. Juvé Noise investigation of a high subsonic, moderate Reynolds number jet using a compressible LES, Theoret. Comput. Fluid Dynam., Volume 16 (2003) no. 4, pp. 273-297

[11] W. Möhring On vortex sound at low Mach number, J. Fluid Mech., Volume 85 (1978), pp. 685-691

[12] J.M. Berhault; M. Sunyach; H. Arbey; G. Comte-Bellot Réalisation d'une chambre anéchoïque revêtue de panneaux et destinée à l'étude des bruits d'origine aérodynamique, Acustica, Volume 29 (1973) no. 2, pp. 69-78

[13] K.B.M.Q. Zaman Far-field noise of a subsonic jet under controlled excitation, J. Fluid Mech., Volume 152 (1985), pp. 83-111

[14] A. Michalke On spatially growing disturbances in an inviscid shear layer, J. Fluid Mech., Volume 23 (1965), pp. 521-544

[15] P. Freymuth On the transition in a separated laminar boundary layer, J. Fluid Mech., Volume 25 (1966), pp. 683-704

[16] J.E. Bridges; F. Hussain Direct evaluation of aeroacoustic theory in a jet, J. Fluid Mech., Volume 240 (1992), pp. 469-501

[17] V. Fleury, C. Bailly, D. Juvé, Shear-layer acoustic radiation in an excited subsonic jet: Models for vortex pairing and superdirective noise, C. R. Mecanique 333 (2005), in this issue

Cited by Sources:

Comments - Policy