MISE EN EVIDENCE ET ETUDE EXPERIMENTALE D’UNE BIFURCATION TURBULENTE REDUCTRICE DES BRUITS AUTO-ENTRETENUS DANS LES ECOULEMENTS.

Abstract : Vortex shedding from shear layers may be driven by the resulting strong acoustical waves A feedback loop causes an intense acoustical noise Conventional methods of noise reduction mainly depending on the frequency range, and using either passive or active noise control techniques, are well-known. These experimental investigations bring to light another way of achieving noise reduction. A very slight auxiliary flow is created by means of a minor geometrical modification in order to breakdown the feedback loop which causes self-sustained tones. It is a passive method in the sense that it does not contain an active control process.  The newest and most important result is the following : it is possible to reach stable paths of flow bifurcations where a high noise reduction is obtained within a large range of flowrates. In other words, by creating a suitable interaction between a main shear layer and thin auxiliary shear layers, noise reduction takes place in a range of 20 to 30 dB which is as efficient as that obtained by passive or active control methods. Moreover, due to the stability of the flow bifurcation path that can be obtained, such a high level of noise reduction is maintained in a large range of the flow parameters. It may be emphasized that such methods are costless compared to certain sophisticated active control methods.
Complete list of metadatas

Cited literature [102 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-02166666
Contributor : Alex Coiret <>
Submitted on : Thursday, June 27, 2019 - 9:13:50 AM
Last modification on : Friday, July 5, 2019 - 1:13:56 AM

File

these_alex_coiret.pdf
Files produced by the author(s)

Identifiers

  • HAL Id : tel-02166666, version 1

Collections

Citation

Alex Coiret. MISE EN EVIDENCE ET ETUDE EXPERIMENTALE D’UNE BIFURCATION TURBULENTE REDUCTRICE DES BRUITS AUTO-ENTRETENUS DANS LES ECOULEMENTS.. Acoustique [physics.class-ph]. Université de La Rochelle, 1999. Français. ⟨tel-02166666⟩

Share

Metrics

Record views

16

Files downloads

7