The transient phenomena of re-oxidation and slag entrapment occurring in the tundish during the ladle change-over process have been proven detrimental to clean steel production.Therefore,an unsteady three-phase turbul...The transient phenomena of re-oxidation and slag entrapment occurring in the tundish during the ladle change-over process have been proven detrimental to clean steel production.Therefore,an unsteady three-phase turbulence model,coupling velocity,temperature,and phase field was established to study the effect of the ladle shroud immersion depth on the slag eye formation,slag entrainment,slag dragging,air dragging,and flow characteristics during the ladle change-over process of a two-strand tundish.The results showed that reducing the immersion depth decreases the high-velocity region area under the slag layer in the quasi-steady process.During the emptying stage,as the molten bath level gradually decreases,the outlet temperature exhibits a trend of initially decreasing and subsequently increasing across all three shroud immersion depths.However,under a 210 mm shroud immersion depth,molten slag and air are dragged into the shroud,forming slag droplets and causing significant fluctuations,with a maximum scalar velocity of 0.0764 m/s at the monitoring point.In the filling stage,air and molten slag are dragged into the molten bath,forming bubbles and slag droplets at an immersion depth of 210 mm.Bubbles are observed within the molten slag layer,which can readily cause an emulsification phenomenon,making it easier to be dragged as slag droplets.Additionally,the slag eye area measured under 210 mm immersion depth at 45 s is 0.303 m^(2),while the maximum scalar velocity of 2.4259 m/s is detected at 12 s.At an immersion depth of 360 mm,the average area of the slag eye is minimized to 0.06268 m2,with corresponding variances of 0.006753,representing the optimal immersion depth.展开更多
In the electroslag remelting process, the electrode molten state is a critical factor determining the ingot quality, while the electrode immersion depth and melting rate are key factors for the stability of the electr...In the electroslag remelting process, the electrode molten state is a critical factor determining the ingot quality, while the electrode immersion depth and melting rate are key factors for the stability of the electroslag re-melting process. Studies were carried out to investigate the microscopic and macroscopic effects of electrode immersion depth and melting rate on the potential distribution and heat density in the slag bath, and on the depth and shape of the molten bath. Based on the finite element method and the numerical solution method, the effect of the electrode immersion depth on the slag bath heat density was researched; the relationship between the electrode immersion depth and the slag resistance was obtained; and the unsteady-state model of the solidification process of the re-melting ingot was solved using the finite difference method. The mathematical model and physical model of the electrode melting process were established and solved; and the corresponding curves between the electrode molten-state and slag-bath physical parameters were obtained. The experimental results verified the simulated results studied in this paper.展开更多
The two-fluid model coupled with population balance model was used for simulating the gas-liquid flow in the Ruhrstahl-Heraeus(RH)degasser.The predicted circulation flow rate was compared with that measured from a wat...The two-fluid model coupled with population balance model was used for simulating the gas-liquid flow in the Ruhrstahl-Heraeus(RH)degasser.The predicted circulation flow rate was compared with that measured from a water model experiment to validate the mathematical model.Then,influence of snorkel immersion depth on liquid circulation flow rate was numerically investigated under an atmospheric pressure of 101 and 84 kPa,respectively.Predicted result indicates that the circulation flow rate of the RH degasser in the high-altitude area was severely reduced because of the decrease in atmospheric pressure.However,increasing the snorkel immersion depth from 0.5 to 0.7 m can compensate for the decrease in atmospheric pressure.Industrial test result indicates that decarburization rate is significantly enhanced by increasing the snorkel immersion depth.Through optimization,the percentage of heats with a final carbon content less than 0.002 wt.%is significantly increased from 22.0%to 96.4%.展开更多
An in-depth study of the complicated trajectory characteristics of skipping stones is carried out in the present work.A three-dimensional numerical simulation validated by acquiring good agreement with experimental re...An in-depth study of the complicated trajectory characteristics of skipping stones is carried out in the present work.A three-dimensional numerical simulation validated by acquiring good agreement with experimental results is established.It is devoted to illustrating five different types of motion responses after the stone impacts the water surface in the o-xy plane,including“dive”,“hydroplaning trout”,“hydroplaning skip”,“stable skip”,and“skipping trout”.Then,the lateral deviations are investigated quantitatively based on dimensionless parameter sin(α+β)cosαin the o-yz plane.Steady interval and linear interval are divided for lateral deviation Z1/D and Z2/D based on the values of(α+β)andα,respectively.The results reveal that(1)Z1/D increases almost linearly with the increasing sin(α+β)cosαat different slopes in different(α+β)intervals;(2)Z2/D increases almost linearly with the increasing sin(α+β)cosαat different slopes in differentαintervals;(3)in linear interval,numerical lateral deviations are much larger than the fitting values at pointsβ/α≥4.5,and much smaller than the fitting values at points 2.3≤β/α<4.3.Finally,a theoretical approach is proposed to predict the maximum immersion depth of trailing edge point P.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52422408 and 52171031)the Liaoning Xingliao Talents-Top-notch Young Talents Project(No.XLYC2203064)+1 种基金the Excellent Youth Fund of Liaoning Natural Science Foundation(No.2023JH3/10200001)the Fundamental Research Funds for the Central Universities(No.N2425004).
文摘The transient phenomena of re-oxidation and slag entrapment occurring in the tundish during the ladle change-over process have been proven detrimental to clean steel production.Therefore,an unsteady three-phase turbulence model,coupling velocity,temperature,and phase field was established to study the effect of the ladle shroud immersion depth on the slag eye formation,slag entrainment,slag dragging,air dragging,and flow characteristics during the ladle change-over process of a two-strand tundish.The results showed that reducing the immersion depth decreases the high-velocity region area under the slag layer in the quasi-steady process.During the emptying stage,as the molten bath level gradually decreases,the outlet temperature exhibits a trend of initially decreasing and subsequently increasing across all three shroud immersion depths.However,under a 210 mm shroud immersion depth,molten slag and air are dragged into the shroud,forming slag droplets and causing significant fluctuations,with a maximum scalar velocity of 0.0764 m/s at the monitoring point.In the filling stage,air and molten slag are dragged into the molten bath,forming bubbles and slag droplets at an immersion depth of 210 mm.Bubbles are observed within the molten slag layer,which can readily cause an emulsification phenomenon,making it easier to be dragged as slag droplets.Additionally,the slag eye area measured under 210 mm immersion depth at 45 s is 0.303 m^(2),while the maximum scalar velocity of 2.4259 m/s is detected at 12 s.At an immersion depth of 360 mm,the average area of the slag eye is minimized to 0.06268 m2,with corresponding variances of 0.006753,representing the optimal immersion depth.
基金financially supported by the Machine Tools Major Project of the Eleventh Five-Year Plan of China(grant No.2009ZX04006-032)
文摘In the electroslag remelting process, the electrode molten state is a critical factor determining the ingot quality, while the electrode immersion depth and melting rate are key factors for the stability of the electroslag re-melting process. Studies were carried out to investigate the microscopic and macroscopic effects of electrode immersion depth and melting rate on the potential distribution and heat density in the slag bath, and on the depth and shape of the molten bath. Based on the finite element method and the numerical solution method, the effect of the electrode immersion depth on the slag bath heat density was researched; the relationship between the electrode immersion depth and the slag resistance was obtained; and the unsteady-state model of the solidification process of the re-melting ingot was solved using the finite difference method. The mathematical model and physical model of the electrode melting process were established and solved; and the corresponding curves between the electrode molten-state and slag-bath physical parameters were obtained. The experimental results verified the simulated results studied in this paper.
基金supported by the National Natural Science Foundation of China (Grant No.52104321)the Natural Science Foundation of Chongqing,China (Grant No.CSTB2023NSCQ-MSX0871)the Science and Technology Research Program of Chongqing Municipal Education Commission (Grant No.KJQN202101404).
文摘The two-fluid model coupled with population balance model was used for simulating the gas-liquid flow in the Ruhrstahl-Heraeus(RH)degasser.The predicted circulation flow rate was compared with that measured from a water model experiment to validate the mathematical model.Then,influence of snorkel immersion depth on liquid circulation flow rate was numerically investigated under an atmospheric pressure of 101 and 84 kPa,respectively.Predicted result indicates that the circulation flow rate of the RH degasser in the high-altitude area was severely reduced because of the decrease in atmospheric pressure.However,increasing the snorkel immersion depth from 0.5 to 0.7 m can compensate for the decrease in atmospheric pressure.Industrial test result indicates that decarburization rate is significantly enhanced by increasing the snorkel immersion depth.Through optimization,the percentage of heats with a final carbon content less than 0.002 wt.%is significantly increased from 22.0%to 96.4%.
基金supported by the National Natural Science Foundation of China(Grant No.11972138).
文摘An in-depth study of the complicated trajectory characteristics of skipping stones is carried out in the present work.A three-dimensional numerical simulation validated by acquiring good agreement with experimental results is established.It is devoted to illustrating five different types of motion responses after the stone impacts the water surface in the o-xy plane,including“dive”,“hydroplaning trout”,“hydroplaning skip”,“stable skip”,and“skipping trout”.Then,the lateral deviations are investigated quantitatively based on dimensionless parameter sin(α+β)cosαin the o-yz plane.Steady interval and linear interval are divided for lateral deviation Z1/D and Z2/D based on the values of(α+β)andα,respectively.The results reveal that(1)Z1/D increases almost linearly with the increasing sin(α+β)cosαat different slopes in different(α+β)intervals;(2)Z2/D increases almost linearly with the increasing sin(α+β)cosαat different slopes in differentαintervals;(3)in linear interval,numerical lateral deviations are much larger than the fitting values at pointsβ/α≥4.5,and much smaller than the fitting values at points 2.3≤β/α<4.3.Finally,a theoretical approach is proposed to predict the maximum immersion depth of trailing edge point P.
