Investigation of the mean and turbulent particle velocity fields in a spouted bed using radioactive particle tracking

A non invasive experimental Radioactive Particle Tracking method (R.P.T.) was used to determine the three-dimensional mean and turbulent particle velocity fields in a spouted bed. The local statistical properties were evaluated with approximately one million data obtained on typically 6 hours of particle tracking. Radial profiles of first and second order moments of the particle velocity field are presented in the spout, the annulus and the fountain region on several axial sections. In addition to the complete description of the solids mean flow pattern, the relevance of a strong anisotropy behavior for particle turbulence field was well established. Thus, this study constitutes an original experimental investigation needed both for a better physical understanding and refined flow modelling of gas-solid flows in spouted beds. Une methode experimentale non-intrusive de Poursuite de Particule Radioactive (R.P.T.) a ete utilisee pour la determination du champ de vitesse tridimensionnel moyen et fluctuant de particules dans un lit a jet. Les proprietes statistiques locales ont ete obtenues sur environ un million de points pendant 6 heures d'acquisitions. Des profils radiaux de moments d'ordre un et deux du champ de vitesse de particules sont presentes dans le cœur, l'anneau et la fontaine en differentes sections axiales. En plus de la description complete de la dynamique moyenne de la phase solide, l'existence d'une anisotropie importante du champ turbulent des particules est clairement etablie. Ainsi, cette etude constitue une base de comparaison originale tant pour une meilleure comprehension physique que dans une perspective de modelisation fiable des ecoulements gaz-solide des lits a jet.

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