2016 Volume 56 Issue 8 Pages 1394-1403
Nozzle clogging is still a standing problem in the continuous casting of steel since the deposition of alumina inclusions inside the Upper Tundish Nozzle (UTN) affects the productivity and the product quality. The present fundamental work studies the effects of inertial, gravitational, buoyant, pressure gradient, and Saffman forces on the deposited inclusion trajectories at the typical adhesion zone inside the UTN, using analytical and numerical techniques. For this, a mathematical model was developed considering the Navier-Stokes equations, the standard k-ε model, and the Lagrangian discrete phase model for a coupled system including the tundish, the UTN, the slide gate, the SEN, and the mould. The results show that the highest inclusion deposition rate is just below a low static pressure zone. At the low static pressure zone the pressure gradient force becomes important, attracting the inclusions to the nozzle wall, and once the inclusions leave this zone, this force does not promote a significant inclusion radial movement. In addition, at the highest deposition zone, the effects of the gravitational and buoyant forces do not promote a significant inclusion radial movement since these are aligned with the direction of the flow stream lines. In contrast, the Saffman force shows an important effect on the deposited inclusions, slowing down the inclusions in the vertical axis and increasing their radial movement.
