Droplets dispersion and deposition measurements in an axisymmetric sudden expansion flow

This study is about droplets dispersion in an axisymmetric sudden expansion flow. It presents in the same experiment facility both droplets dispersion and deposition at the wall. The main phase flow is characterized by PIV measurements. Droplets are injected inside the shear layer, they progressively interact with the main phase turbulence. Two expansion rates and two inlet velocities are considered, allowing thus different responses of droplets to the turbulent structures of the shear layer. Their dispersion in the sudden expansion is analyzed with PIV and PTV measurements. A new method for measuring particles deposition at the wall based on the UV fluorescence of a dye is presented. The droplets deposition rates are analyzed and compared to the particles dispersion in the sudden expansion. The droplets wall normal velocity PDF are calculated close to the wall and analyzed in order to link the deposition rate to the particles dispersion in the near wall region.

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