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Instationnarités dans les décollements compressibles : cas des couches limites soumises à ondes de choc

Abstract : An interaction between an oblique shock wave and a fully developed turbulent boundary layer on a flat plate, at Mach number 2.3, has been studied experimentally.
This kind of interaction, for strong enough shock waves, induces separation and reattachment of the boundary layer, and is characterized by a strong unsteadiness at low frequencies. The origin of this low frequency motions is not well known. It has been partly characterized experimentally in previous studies, and common features have been observed between the present interaction, others configurations (compression ramps, blunt fins, etc...) and subsonic separation, suggesting that the governing mechanisms of the unsteadiness are of same nature.
In this work, Particle Image Velocimetry (PIV) has been used in order to describe the spatial organization of this interaction. A strong statistical link has been shown between the low frequency unsteadiness of the separation shock and the successive contractions/dilatations of the detached bubble. The proposed interpretation is that the large scale movements of the separation shock is linked to the low frequency pulsations of the recirculating bubble, associated with an intermittent fluid realimentation.
An aerodynamic model is proposed and determines the main parameters which influence the time scale of the phenomenon. In particular, this model gives the typical frequency for the unsteady reflected shock. This model has been applied for several experimental configurations, for Mach numbers from 0 to 5, and shows a good agreement with measurements.
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https://tel.archives-ouvertes.fr/tel-00403795
Contributor : Sébastien Piponniau <>
Submitted on : Monday, July 13, 2009 - 11:38:04 AM
Last modification on : Thursday, January 18, 2018 - 1:27:00 AM
Long-term archiving on: : Tuesday, June 15, 2010 - 7:55:58 PM

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Sébastien Piponniau. Instationnarités dans les décollements compressibles : cas des couches limites soumises à ondes de choc. Dynamique des Fluides [physics.flu-dyn]. Université de Provence - Aix-Marseille I, 2009. Français. ⟨tel-00403795⟩

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