Drop model for continuous milli-beads production
Résumé
Production of solid spheres from droplet solidification is gaining more and more interest, but needs a careful control of the drop diameter. The technique of dropping liquid alumina from a nozzle is used for processing the starting materials which are filling the crucibles in sapphire crystal growth technology. In the present work, experimental, theoretical and numerical analysis is carried out in order to describe the time evolution of the drop formation from a capillary tube. The main goal of this study is to develop a physical model able to explain the dynamics of drop formation, with application in drop weight method and production of small alumina balls. A new formula predicting the volume of falling drops is derived from the force balance at the instant of drop detachment. The theoretical predictions are compared to present numerical computations and experimental results of alumina milli-beads production. Based on this model, the crucible and capillary tube geometries and the process parameters can be designed in order to get continuous production of reproducible droplets for mass production.