1. 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:
MEFOS
PHOENICS User Conference

2. Process Introduction MEFOS Tundish Metallurgy Function of Tundish:
Ladle with clean steel 40
ppm O
tot
Slag
20-30 ppm
Stirring
Shroud
Stopper (Ar-bubbling)
10-20 ppm
Nozzle
Mould
Slag+casting powder
Slag+cover powder
Tundish
Blow-Holes
(Ar+Al 2 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
MEFOS
PHOENICS User Conference

3. Objective Problem Arisement MEFOS Two different opinions:
The steel flow in tundish is:
Objective
1, Forced Convection System? OR
2, Mixed Convection System?
Thermal conditions:
1, Heat loss
2, External heating and cooling
3, Variation of inlet temperature
MEFOS
PHOENICS User Conference

4. CFD Causes to This Study !
Two different flow pattern are on my screen
Is this
true ?
MEFOS
PHOENICS User Conference

5. Theoretical ConsiderationF gl u l Gr
bouyancy
inertia ~ ( ) * / Re Dr 3 2 r m . T ul g s 4 74 = @ bD n b D w 00
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.
MEFOS
PHOENICS User Conference

6. Water Model Experiment1 1 l a d l e ( 1 ) t h e r m o c o u p l e I n t e r f a c e c a m e r a 3 6 7 2 1 5 t u n d i s h ( 2 ) 1 9 4 8 M i c r o c o m p u t e r o u t l e t ( 3 )
MEFOS
PHOENICS User Conference

7. Experimental measurements
PHOENICS User Conference
MEFOS
Experimental measurements 50
100
150
200
250
300
350 10 15 20 25 30 35
Time, (s)
Temperature, (¡æ) 7 8
Time, (s) 1 2 3 4 5 6
Temperature, (¡æ) 50
100
150
200
250
300
350 10 15 20 25 30 35
Time, (s)
Temperature, (¡æ) 9 10 50
100
150
200
250
300
350 15 20 25 30 35
Temperature, (¡æ) a
Time, (s) b c d

8. CFD Simulation MEFOS Modeling description1.
3-D
Navier-Stokes equations. 2. S
tandard k- e
two equations model 3. F
ree surface is k
ept at a fixed level. 4.
Fluid flow and temperature are coupled
PHOENICS 3.1, Sun Enterprise 4000,
6 CPU 350 MHz
MEFOS
PHOENICS User Conference

9. Hotter Incoming (1)
MEFOS
PHOENICS User Conference

10. Cooler Incoming (1)
MEFOS
PHOENICS User Conference

11. Schematic of flow pattern
a, equal temperature inlet
b, hotter inlet
c, cooler inlet
MEFOS
PHOENICS User Conference

12. Verification (1) MEFOS No.6 No.10 No.9 No.4 PHOENICS User Conference30 60 90
120
150
180
210
240
270
300
330
282
284
286
288
290
292
294
296
298
302
CFD model
Physical model
Temperature, (K)
Time, (s) 30 60 90
120
150
180
210
240
270
300
330
282
284
286
288
290
292
294
296
298
302
CFD model
Physical model
Temperature, (K)
Time, (s) 30 60 90
120
150
180
210
240
270
300
330
282
284
286
288
290
292
294
296
298
302
CFD model
Physical model
No.6
No.10
Temperature, (K)
CFD model
Physical model
Temperature, (K)
Time, (s) 30 60 90
120
150
180
210
240
270
300
330
282
284
286
288
290
292
294
296
298
302
Time, (s)
No.9
No.4

14. Hotter Incoming (2)
MEFOS
PHOENICS User Conference

15. Cooler Incoming (2)
MEFOS
PHOENICS User Conference

16. Future work MEFOS (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.
MEFOS
PHOENICS User Conference

17. Conclusion MEFOS (1) Dimensionless number Gr/Re can be used to2
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
MEFOS
PHOENICS User Conference