Numerical Simulation of Flow Field, Bubble Distribution and Solidified Shell in Slab Mold under Different EMBr Conditions Assisted with High-Temperature Quantitative Velocity Measurement
Abstract
:1. Introduction
2. Mathematical Model
2.1. Assumptions
- (1)
- Liquid steel and mold flux are incompressible Newtonian fluids;
- (2)
- Liquid steel and mold flux in the mold are in the homogeneous phase, and parameters such as density and viscosity are set to be constants;
- (3)
- The influence of mold oscillation and taper is not considered;
- (4)
- The shape of argon bubbles is spherical, ignoring the breakage and coalescence of argon bubbles;
- (5)
- The influence of Joule heat generated by electric currents is ignored;
- (6)
- The molten steel in the paste zone obeys Darcy’s law;
- (7)
- The influence of liquid steel flow on the electromagnetic field is ignored.
2.2. Electromagnetic Force Model
2.3. Discrete Phase Model
2.4. Multiphase Flow Model
2.5. Large Eddy Simulation and Solidification
2.6. Numerical-Simulation-Related Calculation Parameters
3. Results and Discussion
3.1. Magnetic Flux Density Distribution and Model Verification
3.2. Comparison between the Calculated and Measured Velocities near the Mold Surface
3.3. Effects of Argon Flow Rate and EMBr on Mold Flow Field
3.4. Effects of Argon Flow and EMBr on Argon Bubble Distribution
3.5. Fluctuation on Mold Surface
3.6. Effect of EMBr on Solidified Shell
4. Conclusions
- (1)
- The calculated velocities on the mold surface are in good agreement with the measured values of the industrial experiment at high temperature with the rod deflection method. As the argon flow rate is increased from 0 to 6 L·min−1 and 10 L·min−1, both of the calculated and measured velocities on the mold surface first increase and then decrease. As the EMBr mode changes from Mode 1 without EMBr to Mode 2 with upper coil current 0 A and lower coil current 700 A, and then to Mode3 with upper coil current 300 A and lower coil current 700 A, both of the calculated and measured velocities on the mold surface gradually decrease.
- (2)
- With EMBr Mode 3 and at the argon flow rate of 0 L·min−1, the velocity on the mold surface is too low, which is not conducive to the melting of the mold flux. When the argon flow rate is 6 L·min−1, the jet angle increases, and the velocity on the mold surface increases, which is conducive to heat and mass transfer near the meniscus. When the argon flow rate is further increased to 10 L·min−1, the upper circulating flow is affected by floating up of more argon bubbles; the surface velocity of the mold decreases, and the liquid level fluctuation near the SEN increases.
- (3)
- When the argon flow rate is 6 L·min−1 and the casting speed is 1.9 m·min−1, with EMBr Mode 1, the liquid level fluctuation is too large, which may lead to slag entrainment in the mold. With Mode 2, as the lower circulation stream is restrained by the lower magnitude field, the velocity on the mold surface decreases, but the liquid level fluctuation is still large. With Mode 3, both of the lower and upper circulation streams are restrained by the magnetic field, the velocity on the mold surface is reduced, and the fluctuation is at a relatively reasonable level.
- (4)
- With EMBr Mode 3, when the argon flow rate is 10 L·min−1, due to the strong upward floating of argon bubbles, the jet at the port becomes disordered, and the liquid level fluctuation near the SEN wall intensifies, which increases the risk of slag entrainment and slag layer breaking, as well as the risk of argon bubbles being captured. When the argon flow rate is 6 L·min−1, the liquid level fluctuation of the mold is in a reasonable range under the conditions of Mode 3. Therefore, it is reasonable to control the argon flow rate to be 6 L·min−1.
- (5)
- With Mode 1 and Mode 2, due to no braking or insufficient braking capacity, the jet scours the narrow face violently, resulting in the decrease in thickness of the solidified shell in the range above 0.45 m from the mold surface. With Mode 3, as the impact of the jet on the narrow face is well restrained, the solidified shell thickness of the narrow surface is significantly greater than those in Modes 1 and 2 in the range above 0.45 m from the mold surface.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Parameters | Values | Parameters | Values |
---|---|---|---|
Mold width (mm) | 1050 | Slag thickness (mm) | 15 |
Mold thickness (mm) | 230 | Slag density (kg·m−3) | 2800 |
Mold length (mm) | 800 | Slag viscosity (kg·m−1·s−1) | 0.18 |
SEN submergence depth (mm) | 170 | Liquidus temperature (K) | 1807 |
SEN port angle (°) | 20 | Solidus temperature (K) | 1796 |
SEN port size (mm × mm) | 70 × 90 | Thermal conductivity (W·m−1·K−1) | 34 |
SEN inner diameter (mm) | 78 | Steel latent heat (J·kg−1) | 270,000 |
SEN outer diameter (mm) | 140 | Steel electric conductivity (S·m−1) | 580,000 |
Argon flow rate (L·min−1) | 0\6\10 | Steel magnetic conductivity (H·m−1) | 1.257 × 10−6 |
Argon density (kg·m−3) | 0.4 | Steel viscosity (kg·m−1·s−1) | 0.0062 |
Steel density (kg·m−3) | 7020 | Casting speed (m·min−1) | 1.9 |
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Guo, Y.; Yang, J.; Liu, Y.; He, W.; Zhao, C.; Liu, Y. Numerical Simulation of Flow Field, Bubble Distribution and Solidified Shell in Slab Mold under Different EMBr Conditions Assisted with High-Temperature Quantitative Velocity Measurement. Metals 2022, 12, 1050. https://doi.org/10.3390/met12061050
Guo Y, Yang J, Liu Y, He W, Zhao C, Liu Y. Numerical Simulation of Flow Field, Bubble Distribution and Solidified Shell in Slab Mold under Different EMBr Conditions Assisted with High-Temperature Quantitative Velocity Measurement. Metals. 2022; 12(6):1050. https://doi.org/10.3390/met12061050
Chicago/Turabian StyleGuo, Yi, Jian Yang, Yibo Liu, Wenyuan He, Changliang Zhao, and Yanqiang Liu. 2022. "Numerical Simulation of Flow Field, Bubble Distribution and Solidified Shell in Slab Mold under Different EMBr Conditions Assisted with High-Temperature Quantitative Velocity Measurement" Metals 12, no. 6: 1050. https://doi.org/10.3390/met12061050
APA StyleGuo, Y., Yang, J., Liu, Y., He, W., Zhao, C., & Liu, Y. (2022). Numerical Simulation of Flow Field, Bubble Distribution and Solidified Shell in Slab Mold under Different EMBr Conditions Assisted with High-Temperature Quantitative Velocity Measurement. Metals, 12(6), 1050. https://doi.org/10.3390/met12061050