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Communication Dans Un Congrès Année : 2016

Evaporating droplets tracking by holographic high speed video in turbulent flow

Résumé

The evaporation rate of diethyl ether droplets dispersing in a Homogeneous and isotropic (HI) turbulence is measured by following droplets along their trajectory. Measurements are performed at ambient temperature and pressure by using in-line digital holography. The holograms of droplets are recorded with a single high-speed camera (3kHz) and reconstructed with an inverse problems approach (IPA). IPA provides a measurement of droplet size and location accurate enough to follow the dynamic of the droplets in 3 dimensions as well as their instantaneous evaporation rate though their size evolution. In addition, the thermal-vapor concentration wakes developing around the droplets are visible on holograms. It is found that these wakes when reconstructed using a classical back light propagation method are aligned with the relative Lagrangian velocity seen by the droplets at each time. The relative velocity can be calculated from the droplets equation of motion and the positions and diameter measured by holography and IPA processing, when the orientation of the wake is independently deduced from the phase retrieval of the vapor wake. Droplets trajectories and time evolution of diameter and relative velocity are presented. In a number of cases, the evaporation rate of the droplets changes along the trajectory and deviates from that calculated with a standard film model, showing that turbulence may influence significantly the evaporation process.
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Dates et versions

hal-02404953 , version 1 (11-12-2019)

Identifiants

  • HAL Id : hal-02404953 , version 1

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Loïc Méès, Thibaut Tronchin, Nathalie Grosjean, Jean-Louis Marié, Corinne Fournier. Evaporating droplets tracking by holographic high speed video in turbulent flow. 18th International Symposium on applications of laser techniques to fluid mechanics, Jul 2016, Lisbonne, Portugal. ⟨hal-02404953⟩
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