2020 Volume 19 Issue 4 Pages 276-280
Alumina balls initially placed on the flat bottom wall of a water-filled vessel were agitated by a vertically impinging water jet to crush fly ash particles. A part of the alumina balls was removed from the impingement point to a certain extent. A circular region without any balls was formed on the bottom wall. Only the balls located just outside the perimeter of the circle were found to be moving continuously. Such a restricted region is responsible for the crush of fly ash and, hence, for the size adjustment of fly ash particles. The diameter of the circular region and the area of the restricted region were measured. Meanwhile, when a water jet is introduced into the bath along the curved side wall of the vessel, a semi-ellipsoidal region without alumina balls was formed on the bottom wall of the vessel. The area responsible for fly ash crush was nearly the same as generated by the submerged vertical impinging water jet. From a practical point of view, an unsteady impinging water jet is superior to the above-mentioned steady water jets.
