2006年07月14日

METALLURGICAL AND MATERIALS TRANSACTIONS B VOLUME 32B, DECEMBER 2001-1053，-0001，（）：

-1年11月30日

Biased flow occurs frequently in the slab continuous casting process and leads to downgraded steel quality. A mathematical model has been developed to analyze the three-dimensional biased flow phenomena associated with the effects of static magnetic-field application and argon gas injection in the slab continuous casting process. By moving the submerged entry nozzle (SEN) from center to off-center, the biased flow and vortexing flow in the mold can be reproduced in the numerical simulation. The existence of a vortexing flow is shown to result from three-dimensional biased flow in the mold. A vortex is located at the low-velocity side adjacent to the SEN. The vortex strength depends on the local horizontal velocity of molten steel and decreases gradually with distance from the free surface. The vortexing-zone size depends on the biased distance of the SEN, and the intensity of the vortexing flow depends on the casting speed of the continuous caster. Only when the location and strength of the magnetic field are properly chosen, can the vortexing flow be suppressed by a static magnetic-field application. The effect of argon gas injection on the vortexing flow is not remarkable. The combination of magnetic-field application and argon gas injection can correct the biased flow and suppress the vortexing flow by suppressing the surface velocity and removing the downward velocity near the SEN in the mold.

2006年07月14日

METALLURGICAL AND MATERIALS TRANSACTIONS B VOLUME 31B, DECEMBER 2000-1491，-0001，（）：

-1年11月30日

A mathematical model has been developed to analyze molten metal flow, considering the effects of argon gas injection and static magnetic-field application in the continuous casting process. The k-« turbulence model is used to calculate the turbulent variables. A homogeneous fluid model with variable density is employed to tackle the molten metal-argon gas flow. The electromagnetic force is incorporated into the Navier–Stokes equation, and the effects of boundary conditions of the magnetic field on the velocity distribution near the mold wall are included. A good agreement between the numerically obtained flow-field results and measurements is obtained. The argon gas injection changes the molten metal flow pattern, mainly in the upper portion of the mold. By applying the magnetic field, values of the averaged velocity field in the bulk decrease significantly, and, especially at the top free surface, they become very small, which can cause meniscus freezing. When magnetic-field application and argon gas injection are used together, the external flow field out of the gas plume is significantly suppressed; nevertheless, flotation of gas bubbles is still active and is not affected directly by the magnetic field. Although the penetrating length of the gas plume is shortened, the argon gas bubbles in molten steel still cause fluctuation at the top free surface, which prevents the occurrence of freezing.

2006年07月14日

ISIJ International, Vol. 45 (2005), No.7，-0001，（）：

-1年11月30日

Rotating magnetic field is applied in up-leg of RH vessel to promote the removal of non- metallic inclusions of molten steel and to prolong the life of RH equipment. Physical and mathematical models have been developed to understand the two-phase turbulent flow considering the effect of the rotating magnetic field in the RH vacuum degassing vessel. Water model experiments verified that the gas bubbles can be moved toward the central zone of up-leg of RH vessel as the result of density difference between gas bubbles and liquid in the swirling flow. The larger circulation flow rate can be obtained in RH degassing vessel with the effect of swirling flow. A penetrating velocity, which does not change the equation characteristics but changes solution distribution, is proposed to revise the gas volume fraction conservation equation. A revised gas volume fraction conservation equation is successfully used to solve the gas distribution in RH vessel. If there is no swirling flow, the larger upward velocities and maximum of the gas volume fraction appear near wall of up-leg. If the rotating magnetic field is applied in up-leg, the larger upward velocities occur in the central zone of up-leg. These phenomena agree with the experimental observation. When the rotating electromagnetic force is applied, the numerical results showed that a swirling flow may be produced and extended into the vacuum chamber. As the occurrence of swirling flow in upper part of up-leg, the maximum of gas volume fraction moves toward the center zone of up-leg and the upward parabolic velocity distribution is also formed.

RH vacuum degassing vessel， two-phase flow， rotating magnetic field， swirling flow.，

2006年07月14日

ISIJ International, Vol. 45 (2005), No.1，-0001，（）：

-1年11月30日

A water model experiment was conducted to observe the vortexing flow in the steel slab continuous casting mold, the snake-shaped Plexiglas mold was designed to simulate the actual caster. The camera was used to record the flow patterns, which were visualized by injecting the black sesames into water. The changes of shape of single vortex and two vortices with time have been observed during experiments. A numerical model has been developed to analyze the vortexing flow, which may be produced by moving the submerged entry nozzle from center to off-center in the slab continuous casting of steel. According to the numerical results, the vortexing flow is resulted from three-dimensional biased flow in the mold. A vortex is located at the low velocity side adjacent to the submerged entry nozzle. The vortex strength depends on the local horizontal velocity of fluid and decreases gradually with distance from the free surface. The vortexing zone size depends on the biased distance of the submerged entry nozzle, and intensity of the vortexing flow depends on the casting speed of the continuous caster.

continuous casting， water model， simulation， vortexing flow.，

2006年07月14日

ISIJ International, Vol. 43 (2003), No.6，-0001，（）：

-1年11月30日

Numerical estimation has been conducted to analyze the motion of inclusion considering the effects of argon gas injection and magnetic field application in the continuous casting of slab. The fluid velocity field was obtained by solving the Navier–Stokes equations with electromagnetic force, and the trajectories of inclusion particles are calculated based on the computed velocity field. A reasonable agreement between numerical and experimental trajectory for single sphere was obtained using the water model. The movements of particles are traced in cases with and without the magnetic field and argon gas injection. The results show that some particles after spiral movements re-enter the jet zone of molten steel, and then enter the opposite circulation zone. Inclusions in the upper circulation zone are easily removed. Argon gas injection increases the removal rate of inclusions. The spiral trajectories of inclusion particles disappear when the magnetic field is applied, and the particle velocities decrease significantly. The argon gas injection and magnetic field application are effective for the control of the inclusions.

continuous casting， inclusion， argon gas injection， magnetic field， computer simulation.，

• 李宝宽 邀请

东北大学，辽宁

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