1. Modeling of Two-Phase Flow in RH Vacuum Degassing Vessel With the Effect of Rotating Magnetic field Baokuan Li Northeastern University, China Fumitaka Tsukihashi The University of Tokyo, Japan z y x o

2. To promote the removal of non- metallic inclusions of molten steel. To increase the flow rate of molten steel in RH vacuum degassing vessel. To prolong the life of RH equipment. Vacuum water Pump Air r θ x z y o Research motivation

3. To concentrate the argon gas bubbles and inclusions in central zone of up-leg of RH vessel by using the centripetal force, which is produced as the result of density difference between gas bubbles or inclusions and molten steel in the swirling flow. Therefore, collisions and coalescences increase. Swirling flow is produced by the application of rotating magnetic field. Vacuum water Pump Air r θ x z y o Research ideas

4. Gas distributor Nozzle distribution Rotameter Manometer Ultrasonic flowmeter RH degassing vessel Impeller Water model experiments examine the research ideas

5. Effect of impeller input power on gas bubbles distribution, Q=0.5 m3/h. (a) 0, (b) 20 W, (c) 25 W and (d) 35 W (a)(c)(d)(b)

6. 6 7 8 9 10 05 152025303540 6.944 × 10 -5 m 3 /s 11.111 × 10 -5 m 3 /s 16.667 × 10 -5 m 3 /s Circulation flow rate, 10 -5 m 3 /s Input power, W Effect of plane blade impeller on circulation flow rate of RH vessel

7. Mathematical model To develop a mathematical model for the two-phase turbulent flow in the RH vessel with the rotating magnetic field in the up- leg. To analyze the gas bubbles driven circulation flow characteristics in RH degassing vessel with the swirling flow.

8. Formulation Spitzer et al. [1]

9. Centripetal force and horizontal slip velocity caused by rotating magnetic field Penetrating velocity and slip velocity Vertical slip velocity Horizontal penetrating velocity: Q g : total argon gas flow rate, n :nozzle number A : cross nozzle inlet area α : gas volume fraction (at inlet α 0 )

10. Boundary conditions and solution method Flow field Gas volume fraction

11. Vacuum water Pump Air r θ x z y o Schematic of physical model of RH degassing vessel with the rotating magnetic field.

12. Calculated flow velocities at horizontal sections of RH degassing vessels, (a) up-leg, (b) bottom of vacuum chamber, (c) middle of vacuum chamber, and (d) surface of vacuum chamber. (a) (d)(c) (b) (a) (b) (c) (d)

13. 0 0.1 0.2 0.3 0.4 0.5 0.6 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 0.10.20.30.40.5 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 0.10.2 0.30.40.5 Computed gas volume fraction at main sections of RH degassing vessels, (a) no swirling flow (b) with swirling flow. (a) (b)

14. 0.1 0.2 0.3 0.4 0.5 -0.04 0 0.04 Gas volume fraction Diameter of up-leg, m No swirling flow With swirling flow Gas volume distribution of RH degassing vessel Velocity distribution of RH degassing vessel

15. CONCLUSIONS Water model experiments verified that the gas bubbles may be moved toward the central zone of up-leg of RH vessel in the swirling flow. The numerical results showed that a swirling flow may be produced and extended into the vacuum chamber in case that rotating magnetic field is applied in up-leg. The maximum of gas volume fraction moves toward the center zone of the up-leg. The larger circulation flow rate can be obtained in RH degassing vessel with the effect of swirling flow.

16. Thank you!