Hydrodynamic Behavior of Sphere Penetrating into Water Bath Covered with Oil Layer

To meet the increasing demand for low-impurity steel products, powder top blowing has been applied to the steelmaking process. Powder reagents penetrating deeper into the molten metal lead to longer resident time and higher efficiency of refining. Many studies have been performed on the basis of cold model experiments with a single liquid phase for clarifying the penetration behavior of the particle. However, the effects of the second liquid phase have been reported little whereas molten slag often exists on the surface of molten metal in the steelmaking process. In the present work, the sphere was penetrated into the fluids consisting of a silicone oil layer and water bath. The time variation of the penetration depth of the sphere was measured with a high-speed camera. Effects of the type and size of the sphere, entry velocity, and oil depth were estimated. As a result, the stagnation of penetration occurred under the condition of no air column behind the sphere. On the other hand, a thin oil layer led to no stagnation and deeper penetration due to promoting the formation of air or oil columns. However, an oil layer thicker than 2 mm suppressed the penetration by decreasing the kinetic energy under the condition of high viscosity. The same penetration behavior was observed with a smaller sphere. However, the behavior was more sensitive to the effect of buoyant force because the size of the residual bubble on the surface of the sphere became relatively bigger than the sphere.