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| Genre/Form: | Thèses et écrits académiques |
|---|---|
| Material Type: | Document, Thesis/dissertation, Internet resource |
| Document Type: | Internet Resource, Computer File |
| All Authors / Contributors: |
Alicia Aguilar Corona; Olivier Masbernat; Institut national polytechnique (Toulouse / 1969-....). |
| OCLC Number: | 690834954 |
| Notes: | L'impression du document donne 190 p. Titre provenant de l'écran-titre. |
| Description: | 1 online resource |
| Responsibility: | par Alicia Aguilar Corona ; sous la direction de Olivier Masbernat. |
Abstract:
The susceptibility to intergranular corrosion 2024 aluminium alloy is mainly influenced by three parameters : the metallurgical state of the material, the physical and chemical parameters characteristic of the environment and the stress state of the material. The first part of this work is devoted to the determination of relevant parameters to describe intergranular corrosion. A new way of quantifying intergranular corrosion was set up using the reduction of mechanical properties of the corroded material. Then, the second part is dedicated to the influence of the environmental parameters and the stress state on the susceptibility of the alloy to intergranular corrosion. Both of these factors are of first order related to the growing kinetics of intergranular corrosion. The whole results allow us to establish intergranular corrosion growing laws taking into account the environment.
Dans ce travail, les trajectoires 3-D de particules marquées dans un lit fluidisé liquide ont été mesurées par vidéo dans un milieu d'indices optiques ajustés, dans une plage étendue de concentration. Les paramètres de l'écoulement étudié correspondent à des nombres de Reynolds particulaire élevés (O(10)<Rep<O(103)) et des nombres de Stokes intermédiaires (O(1)<St<O(10)) L'évolution de l'énergie cinétique fluctuante des particules en fonction de la concentration a été modélisée et interprétée dans le cadre de la théorie cinétique. Le coefficient d'autodiffusion des particules a été identifié dans les plans horizontal et vertical, et modélisé grâce à une analyse comparative d'échelles de temps. La fréquence et le coefficient de restitution des collisions ont été mesurés et comparés aux modèles existants.
Besides its interest as an industrial application in various processes, liquid fluidization builds up an interesting test case regarding the validation of two-phase flow modelling. The lack of reliable and detailed experimental data about particle agitation in this type of flow is one important motivation to this study. In this work, the random motion of mono-dispersed particles in a liquid fluidized bed has been measured and processed from video recordings, using a refractive index matching method. 3-D trajectories of coloured particles have been collected in a wide range of solid fraction, and statistical quantities have been derived in the range of high particle Reynolds number (O(10)<Rep<O(103) and intermediate Stokes number (O(1)< St<O(10)). The evolution of the particle velocity variance as a function of solid fraction has been modelled and interpreted in the frame of kinetic theory of granular flows (KTGF). The fluctuating kinetic energy of the continuous phase measured by PIV, is significantly larger than that of the dispersed phase and varies almost linearly as a function of the slip velocity. The existence of a diffusive motion of the particles has been demonstrated and the self-diffusion coefficient has been identified using two distinct methods, the velocity autocorrelation function and the variance of the particle displacement. The comparison of characteristic time scales of the particles and the fluid at small and large scales allowed the formulation of scaling laws for this quantity. Finally, the collisions frequency and particle-wall rebound have been measured and analyzed in the frame of existing theories.
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