Characteristics of flotation, sedimentation and entrainment of particle in agitated liquid

Shin Ichi Shimasaki, Toshiyuki Wada, Shoji Taniguchi

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The characteristics of particle entrainment from free surface or bottom wall into mechanically agitated water have been studied to clarify the inclusion behavior in liquid metal. The critical agitation speed, nc, at which a 50% of particle is entrained into bulk water is measured under steady state by using buoyant particles (glass balloon and silica balloon) and sedimental particles (glass bead). It is found that the dependence of nc, on the particle diameter, dp, is different between the buoyant and the sedimental particle. For the case of the buoyant particle, nc is independent of dp, whereas for the sedimental particle nc increases with increasing dp. To account for this difference, two transition times are investigated. One is the entraining time, t1, which is the time needed to reach a steady state after a sudden imposition of agitation with various speeds. The other is the floating/sinking time, t2, which is the time required to reach a steady state after a sudden decrease in agitation speed from a high speed achieving uniform particle dispersion to lower agitation speeds. It is thought that the balance between t1 and t2 should determine the amount of entrained particles in bulk water under steady-state experiments. For the case of the buoyant particle, the dependencies of t1, and t2 on dp are almost same, so that the value of nc does not depend on dp. On the other hand, for the case of the sedimental particle, the dependence of t1, on dp is smaller than that of t2, so that nc increases with increasing dp. By the VTR observation of the particle entrainment from the free surface or bottom wall, particles are found to be entrained mainly by vertical vortices formed in the agitation vessel.

Original languageEnglish
Pages (from-to)637-644
Number of pages8
JournalTetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
Volume89
Issue number6
DOIs
Publication statusPublished - 2003 Jun

Keywords

  • Agitation vessel
  • Clean metals
  • Inclusion particle
  • Particle entrainment
  • Turbulent flow
  • Vortex
  • Water-model experiment

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Metals and Alloys
  • Materials Chemistry

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