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z. y. x. o. 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. θ. r. z. y. x. o. Research motivation. Vacuum.
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z y x o 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
θ r z y x o Research motivation Vacuum 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. Pump Air water
θ r z y x o Research ideas 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 Pump Air water
Water model experiments examine the research ideas Impeller Gas distributor Manometer Rotameter Nozzle distribution RH degassing vessel Ultrasonic flowmeter
( a) ( b) ( c) ( d) 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
10 9 8 Circulation flow rate, 10-5 m3/s 7 6.944×10-5m3/s 6 11.111×10-5m3/s 16.667×10-5m3/s 5 10 15 20 25 30 35 40 0 Input power, W Effect of plane blade impeller on circulation flow rate of RH vessel
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 circulationflow characteristics in RH degassing vessel with the swirling flow.
Spitzer et al. [1] Formulation
Up - leg Nozzle z Gas jet zone 1 2 y x Penetrating velocity and slip velocity Horizontal penetrating velocity: Qg : total argon gas flow rate, n :nozzle number A : cross nozzle inlet area α : gas volume fraction (at inlet α0) Centripetal force and horizontal slip velocity caused by rotating magnetic field Vertical slip velocity
Boundary conditions and solution method Flow field Gas volume fraction
Vacuum Pump Air θ r z water y x o Schematic of physical model of RH degassing vessel with the rotating magnetic field.
(d) (c) (b) (a) (a) (b) (c) (d) 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.
0.7 0.7 0.6 0.6 0.6 0.5 0.5 0.5 0.4 0.4 0.4 0.3 0.3 0.3 0.2 0.2 0.2 0.1 0.1 0.1 0 0 0.3 0.4 0.5 0.1 0.2 0.1 0.2 0.3 0.4 0.5 0 0 0 (b) (a) Computed gas volume fraction at main sections of RH degassing vessels, (a) no swirling flow (b) with swirling flow.
0.8 0.5 0.7 0.4 0.6 0.5 0.3 Gas volume fraction Vertical velocity, m/s 0.4 0.2 0.3 0.2 0.1 0.1 0.04 -0.04 0 -0.04 0.04 0 Diameter of up-leg, m Diameter of up-leg, m No swirling flow With swirling flow No swirling flow With swirling flow Velocity distribution of RH degassing vessel Gas volume distribution of RH degassing vessel
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.