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Stabilité et atomisation des nappes liquides

Abstract : The atomization of a liquid sheet into dispersed droplets is a widespread phenomenon embracing many natural and industrial processes. This experimental study is devoted to the understanding of break-up mechanisms. Two regimes are considered.

The first one corresponds to a stable state, the sheet stays smooth. The sheet is formed by the impact of two round jets at an angle. It is discovered that a coupling between the sheet thickness modulations and capillary destabilization of the rim leads to drops formation. This thickness perturbations are due to the injection conditions which govern the sheet fragmentation.

Because of the velocity difference between the water and the air, a shear instability develops at the interface liquid/gas and antisymetrical waves propagate along the sheet. This second regime is studied by axisymmetric, radially expanding sheets formed by the impact of a liquid jet on a solid surface which oscillates vertically. The waves features created by the impact rod oscillation (velocity, amplitude, ...) are well described by a linear stability analysis. Liquid is submitted to a transient acceleration imposed by the surface undulations. This trigs a Rayleigh-Taylor instability leading to azimuthal thickness modulations. The thickness field governs the rim shape which exhibits cusps, or indentations at the tip of which ligaments emerge and break into drops. A model including the developpement of both instabilities allows us to predict the atomisation characteristics (sheet size, drops velocity and size). Other experimental configurations involving accelerations and sheets thickness modulations are also investigated.
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Contributor : Nicolas Bremond <>
Submitted on : Wednesday, February 1, 2006 - 1:41:19 PM
Last modification on : Tuesday, March 30, 2021 - 3:19:25 AM
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  • HAL Id : tel-00011518, version 1

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Nicolas Bremond. Stabilité et atomisation des nappes liquides. Dynamique des Fluides [physics.flu-dyn]. Université de Provence - Aix-Marseille I, 2003. Français. ⟨tel-00011518⟩

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