Experimental studies of liquid-liquid dispersion in a turbulent shear flow
نویسنده
چکیده
We built up an experiment to study liquid-liquid dispersions in a turbulent Taylor-Couette flow, produced between two counterrotating coaxial cylinders, of radii ri = 100mm and ro = 110mm (gap ratio η = ri/ro = 0.909). The useful length is L = 185mm. There is a space of 10mm between the cylinders bottom ends and a free surface on the top. The cylinders rotation rates ωi and ωo can be set independently. We use the set of parameters defined in (2): a mean Reynolds number Re based on the shear and on the gap; and a “Rotation number” Ro which is zero in case of perfect counterrotation (riωi = −roωo). At maximal rotation frequency, Re ≃ 5.6× 10 4 for pure water. For the two-phases studies, we use a low-viscous oil (Shell Macron 110), with μ = 3 × 10 Pa.s, ρ = 800 kg.m. The acqueous phase is either pure water or an NaI solution with a refractive index matched to that of oil (1.445 at 20C). The viscosity, density and interfacial tension for the NaI are μ = 2 × 10 Pa.s, ρ = 1550 kg.m and σ ≃ 15mN.m. The viscosity ratio is close to unity and the density ratio is close to 2. We give here some preliminary results on thresholds for dispersion, and on the increase of wall shear stress, based on global measurements of the torque T , using an HBM T20WN rotating torquemeter.
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تاریخ انتشار 2008