ON THE BEHAVIOR OF MICRO INCLUSIONS AND BUBBLE BURSTING

The control of non-metallic inclusions is a critical challenge in secondary steelmaking, where the interaction between molten steel and slag, combined with gas stirring, creates complex flow phenomena that influence inclusion behavior. This thesis investigates inclusion formation and transport using a two-phase approach: a scaled-down water model of a gas-stirred ladle and a detailed study of bubble bursting dynamics at the interface.

In the first phase, a 1:10 scale two-dimensional water ladle model was developed to simulate stirring-induced flow at a water-oil interface, representing the steel-slag boundary. High-speed imaging and quadrant-based particle tracking were used to monitor inclusion-like particle behavior at varying gas injection rates. Results showed that particle count increased rapidly upon stirring and stabilized after approximately 180 seconds, suggesting an equilibrium in inclusion dispersion.

In the second phase, the study focused on bubble bursting as a localized mechanism of particle displacement. Smoke-filled bubbles were placed on solid surfaces and captured using high-speed cameras. The bursting and post-burst flow of bubbles were analyzed using MATLAB PIVLab. Velocity trends were extracted across multiple bubble sizes, revealing stage-wise jet development, vortex formation, and size-dependent differences in bursting direction.

Together, the findings demonstrate that inclusion behavior in steelmaking can be influenced not only by gas stirring but also by transient surface phenomena like bubble bursting. This work provides new insights into inclusion control mechanisms and establishes a foundation for further study of interfacial effects in ladle metallurgy.