2007 Volume 47 Issue 5 Pages 633-637
The separation of inclusions with sizes less than several micrometers is very difficult due to their slow terminal velocity. Thus, increasing the volume of inclusion is essential for accelerating the removal of inclusions, and several methods for enhancing collision frequency of inclusions have been proposed, hitherto. Their collision behavior, however, has not been directly observed yet. In this study, by using a water model, the collision rate of polystyrene particles simulating inclusions in a molten steel was quantified by direct observation of the particle collision behavior in a turbulent flow. The collision rate of the particles counted by use of an image analysis method was compared with a theoretical collision rate, which was calculated by substituting the turbulent energy dissipation rate obtained in a numerical analysis into the Saffman–Turner's equation. In the range with large turbulent energy dissipation rate beyond 0.06 m2/s3, the observed collision rates deviated above the theoretical values. In view of this, the Saffman–Turner's equation has been modified so that it can be applied to the range with large turbulent energy dissipation rate.
