2000 Volume 40 Issue 7 Pages 685-691
In continuous casting molds of steel, mold powder is placed on the meniscus of molten steel in order to prevent heat loss from the meniscus and to use it as a lubricant between the solidifying steel and the mold. The mold powder is sometimes entrapped into the molten steel. Such mold powder entrapment affects the quality of the steel product significantly. In this study we focused on the shear flow instability between the molten steel flow and mold powder as one of causes for the mold powder entrapment and investigated the effect of the kinematic viscosity of the mold powder on the onset of the entrapment. Model experiments were carried out using salt water and some kinds of silicone oils. The velocity of flow around an interface between the silicone oil and salt water was measured with a particle imaging velocimetry (PIV) based on the cross-correlation method. The kinematic viscosity of silicone oil hardly affected the critical flow velocity for the onset of the mold powder entrapment caused by Kelvin–Helmholtz instability, but it affected the wave length of the instability.