부산대학교 도서관

Single argon bubble dynamics in liquid steel under Ruhrstahl–Heraeus (RH) vacuum conditions were simulated using the volume of fluid method, and the ideal gas law was used to consider bubble growth due to heat transfer and pressure drop. Additional simulation with a constant bubble density was also performed to validate the numerical method, and the predicted terminal bubble shape and velocity were found to agree with those presented in the Grace diagram and calculated by drag correlation, respectively. The simulation results under RH conditions indicate that the terminal bubble shape and velocity cannot be reached. The primary bubble growth occurs within a rising distance of 0.3 m owing to heating by the high-temperature liquid steel; subsequently, the bubble continues to grow under equilibrium with the hydrostatic pressure. When the initial diameter is 8–32 mm, the bubble diameter and rising velocity near the liquid surface are 80–200 mm and 0.5–0.8 m/s, respectively. The bubble rises rectilinearly with an axisymmetric shape, and the shape evolution history includes an initial sphere, (dimpled) ellipsoid, and spherical cap with satellite bubbles.