Presentation on theme: "Investigation on the Convection Pattern of Liquid Steel in the Continuous Casting Tundish by Theoretical Analysis, Water Model Experiment and CFD Simulation."— Presentation transcript:
Investigation on the Convection Pattern of Liquid Steel in the Continuous Casting Tundish by Theoretical Analysis, Water Model Experiment and CFD Simulation D. Y. Sheng Lage Jonsson Process Metallurgy Department, MEFOS, S 97125, Lulea, Sweden Tel: Fax: PHOENICS User Conference MEFOS
Process Introduction PHOENICS User Conference MEFOS Ladle with clean steel 40 ppm O tot Slag ppm Stirring Shroud Stopper (Ar-bubbling) ppm Nozzle Mould Slag+casting powder Slag+cover powder Tundish Blow-Holes (Ar+Al 2 O 3 ) BOF EAF BF Function of Tundish: Tradition: 1, Steel distribution vessel Modern: 2, Inclusion removal 3, Alloy trimming 4, Superheat control 5, Homogenisation Tundish Metallurgy
PHOENICS User Conference MEFOS Problem Arisement Two different opinions: The steel flow in tundish is: 1, Forced Convection System? OR 2, Mixed Convection System? Thermal conditions: 1, Heat loss 2, External heating and cooling 3, Variation of inlet temperature Objective
PHOENICS User Conference MEFOS CFD Causes to This Study ! Two different flow pattern are on my screen Is this true ?
PHOENICS User Conference MEFOS Theoretical Consideration F F gl ul Gr bouyancy inertia ~ ()*(/) ()*(/) ~ Re (/Re) (/) (/).Gr glT ul gTl u T s s s sss s s (/Re) (/) (/).Gr glT ul gTl u T w w w www w w Dimensional Anaysis: Tundish Water Model (1) Even one degree temperature difference in the tundish, buoyancy can not be ingored. (2) Water model can be used to simulate the convection pattern due to similar of this dimensionless number.
PHOENICS User Conference MEFOS Water Model Experiment Interface Microcomputer ladle (1) tundish (2) thermocouple camera outlet (3)
Temperature, (¡æ) d c b a Time, (s)
PHOENICS User Conference MEFOS CFD Simulation 1. 3-DNavier-Stokes equations. 2. Standard k- two equations model 3. Free surface iskept at a fixed level. 4. Fluid flow and temperature are coupled Modeling description PHOENICS 3.1, Sun Enterprise 4000, 6 CPU 350 MHz
PHOENICS User Conference MEFOS Hotter Incoming (1)
PHOENICS User Conference MEFOS Cooler Incoming (1)
PHOENICS User Conference MEFOS Schematic of flow pattern a, equal temperature inlet b, hotter inlet c, cooler inlet
CFD model Physical model Temperature, (K) Time, (s) No.6No.10 No.9 No.4
PHOENICS User Conference MEFOS Hotter Incoming (2)
PHOENICS User Conference MEFOS Cooler Incoming (2)
PHOENICS User Conference MEFOS Future work (1) Turbulence model of the transition region (2) Use the CFD model for real tundish simulation (3) Considersing the heat loss surrounding and additional heat source (4) Time dependent inlet temperature variation will be considered.
PHOENICS User Conference MEFOS Conclusion (1) Dimensionless number Gr/Re 2 can be used to set up thermal similarity between water model and actual tundish (2) Thermal buoyancy driven flow is obvious in the non-isothermal water model (3) CFD simulation keeps good agreement with mesurement (4) The tundish is a mixed convection system