Etude expérimentale des structures d'écoulements diphasiques air-eau en co-courant dans un tube circulaire sous diverses conditions d'entrées

Résumé Un dispositif expérimental est conçu et réalisé afin d'analyser l'écoulement air-eau dans un tube circulaire de 3 mm de diamètre dans diverses positions. Diverses conditions d'admission pour le débit d'air et d'eau sont examinées couvrant une gamme de vitesses apparentes : JL = 0.00078 à 0.0786 m/s et JG = 0.002 à 3.538 m/s, respectivement. Des mesures de pressions à l'entrée et à la sortie de la section de test associées à des visualisations par caméra ont été réalisés afin d'analyser les différentes structures d'écoulements et de dégagé des cartographies de structures d'écoulements

Temperature And Pressure Field Visualizations In A Porous Media Dried In Superheated Steam

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Porosity Of Randomly Packed Beds Of Rigid Fibers : An Experimental Study

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Experimental And Numerical Analysis Of Drying Of Particles In Superheated Steam

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Effect of Shear-Induced Diffusion on the Transfer of Heat across a Sheared Suspension

7th International Conference on Micromechanics of Granular Media (Powders and Grains), Sydney, AUSTRALIA, JUL 08-12, 2013International audienceSuspensions of non-Brownian particles undergoing shear provide a quasi-unique system where mixing occurs spontaneously at low Reynolds number. In essence, particles behave in the fluid as so many ``stirrers''. The questions raised are how do they affect the transport of heat/mass across sheared suspensions ? What will be the influence of the particle size, their volume fraction and the applied shear ? By using an index matched suspension and a laser induced fluorescence imaging technique, we were able to measure individual particle trajectories and correlate the particle diffusion motion to the thermal diffusion of the suspension. Shear-induced diffusion causes a significant enhancement (> 200%) of the suspension transport properties. Simulations which combine a Lattice Boltzman technique to solve the flow and a passive Brownian tracer algorithm to solve for the transfer of heat are in very good agreement with experiments

Heat transfer across sheared suspensions: role of the shear-induced diffusion

International audienceSuspensions of non-Brownian spherical particles undergoing shear provide a unique system where mixing occurs spontaneously at low Reynolds numbers. Through a combination of experiments and simulations, we investigate the effect of shear-induced particle diffusion on the transfer of heat across suspensions. The influence of particle size, particle volume fraction and applied shear are examined. By applying a heat pulse to the inner copper wall of a Couette cell and analysing its transient temperature decay, the effective thermal diffusivity of the suspension, α, is obtained. Using index matching and laser-induced fluorescence imaging, we measured individual particle trajectories and calculated their diffusion coefficients. Simulations that combined a lattice Boltzmann technique to solve for the flow and a passive Brownian tracer algorithm to solve for the transfer of heat are in very good agreement with experiments. Fluctuations induced by the presence of particles within the fluid cause a significant enhancement (>200 %) of the suspension transport properties. The effective thermal diffusivity was found to be linear with respect to both the Péclet number (Pe = ˙ γ d 2 /α 0 100) and the solid volume fraction (φ 40 %), leading to a simple correlation α/α 0 = 1 + βφPe where β = 0.046 and α 0 is the thermal diffusivity of the suspension at rest. In our Couette cell, the enhancement was found to be optimum for a volume fraction, φ ≈ 40 %, above which, due to steric effects, both the particle diffusion motion and of the effective thermal diffusion dramatically decrease. No such correlation was found between the average particle rotation and the thermal diffusivity of the suspension, suggesting that the driving mechanism for enhanced transport is the translational particle diffusivity. Movies are available with the online version of the paper

Experimental and Numerical Analysis of Drying of Particles in Superheated Steam

International audienc

Etude Expérimentale Des Empilements De Fibres. Porosité Et Ecoulements

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Experimental Study of Convective Boiling in a Porous Medium: Temperature Fields Analysis

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Basic experiments on flow and heat transfer in porous media, emphasis on bottom injection

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