Investigation on the Convection Pattern

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 [phone]
Fax [phone]
Email sheng_at_mefos.se
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Process Introduction
Function of Tundish
Tradition
1, Steel distribution vessel
Modern
2, Inclusion removal
3, Alloy trimming
4, Superheat control
5, Homogenisation
Tundish Metallurgy
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Problem Arisement
Two different opinions
The steel flow in tundish is
Objective
1, Forced Convection System?
OR
2, Mixed Convection System?
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CFD Causes to This Study !
Two different flow pattern are on my screen
Is this
true ?
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Theoretical Consideration
(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.
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Water Model Experiment
1
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
t
u
n
d
i
s
h
(
2
)
M
i
c
r
o
c
o
m
p
u
t
e
r
o
u
t
l
e
t
(
3
)
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Temperature, (æ)
b
a
Time, (s)
c
d
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CFD Simulation
Modeling description


1.

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
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Hotter Incoming (1)
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Cooler Incoming (1)
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Schematic of flow pattern
a, equal temperature inlet
b, hotter inlet
c, cooler inlet
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CFD model
Physical model
No.6
No.10
Temperature, (K)

Time, (s)
No.9
No.4
13
(No Transcript)
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Hotter Incoming (2)
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Cooler Incoming (2)
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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.
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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
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