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Modeling of Two-Phase Flow in RH Vacuum Degassing Vessel With the Effect of Rotating Magnetic field
Baokuan LiNortheastern University, China
Fumitaka TsukihashiThe University of Tokyo, Japan
z
y
xo
To promote the removal of non- metallic inclusions of molten steel.
To increase the flow rate of molten steel in RH vacuum degassing vessel.
To prolong the life of RH equipment.
Vacuum
water
Pump
Air
r
θ
x
z
y
o
Research motivation
To concentrate the argon gas bubbles and inclusions in central zone of up-leg of RH vessel by using the centripetal force, which is produced as the result of density difference between gas bubbles or inclusions and molten steel in the swirling flow. Therefore, collisions and coalescences increase.
Swirling flow is produced by the application of rotating magnetic field.
Vacuum
water
Pump
Air
r
θ
x
z
y
o
Research ideas
Gas distributor
Nozzle distribution
Rotameter
Manometer
Ultrasonic flowmeterRH degassing vessel
Impeller
Water model experiments examine the research ideas
Effect of impeller input power on gas bubbles distribution, Q=0.5 m3/h. (a) 0, (b) 20 W, (c) 25 W and (d) 35 W
(a) (c) (d)(b)
67
89
10
0 5 10
15
20
25
30
35
40
6.944×10-5m3/s
11.111×10-5m3/s
16.667×10-5m3/s
Cir
cula
tion
flo
w r
ate,
10-5
m3 /
s
Input power, W
Effect of plane blade impeller on circulation flow rate of RH vessel
Mathematical model
• To develop a mathematical model for the two-phase turbulent flow in the RH vessel with the rotating magnetic field in the up-leg.
• To analyze the gas bubbles driven circulation flow characteristics in RH degassing vessel with the swirling flow.
( )
( )
V
V V V p F g
02
e
FormulationSpitzer et al. [1]
k turbulence model
= g ( )1 Liq
rr
vBF
rr
vBF mr
)(2
1
)(8
1
20
32220
cossin
sincos
FFF
FFF
ry
rx
)()()()()()(zzyyxxz
wwy
vvvx
uuu eeeslipslipinslipin
)(2gLr rF
Centripetal force and horizontal slip velocity caused by rotating magnetic field
Up-leg
Nozzle
zy
x
Gas jet zone1 2
9
)(222 rR
V gLr
sin,cos rsliprslip Vv Vu
Penetrating velocity and slip velocity
])(lnexp[)lnexp()exp( 2210 ggslip dadaaw
Vertical slip velocity
Horizontal penetrating velocity:
Qg : total argon gas flow rate, n :nozzle number A : cross nozzle inlet area
α : gas volume fraction (at inlet α0)
nA
Qvu g
inin
Boundary conditions and solution method
Flow field
Gas volume fraction
Blackage technique
Volume factor ffor fluid
for solidArea factor f
for fluid
for solid
Free surface and symmetrical sections:Vn
Near wall The wall law function is used to calculate k and
V A
in
e
1
0
1
0
0 0
,
,,
,
,
,
: , ,
Inlet is calculated by Thermodynamic equation of gas
Other sections
:
:
n
in
0
Vacuum
water
Pump
Air
r
θ
x
z
y
o
Schematic of physical model of RH degassing vessel with the rotating magnetic field.
Calculated flow velocities at horizontal sections of RH degassing vessels, (a) up-leg, (b) bottom of vacuum chamber, (c) middle of vacuum chamber, and (d) surface of vacuum chamber.
(a)
(d)(c)
(b)
(a)
(b)(c)(d)
0
0.1
0.2
0.3
0.4
0.5
0.6
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 0.1 0.2 0.3 0.4 0.50
0.1
0.2
0.3
0.4
0.5
0.6
0.7
00.1 0.2 0.3 0.4 0.5
Computed gas volume fraction at main sections of RH degassing vessels, (a) no swirling flow (b) with swirling flow.
(a) (b)
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
-0.04 0 0.04
Ver
tica
l vel
ocit
y, m
/s
Diameter of up-leg, m
No swirling flowWith swirling flow0.1
0.2
0.3
0.4
0.5
-0.04 0 0.04
Gas
vol
ume
frac
tion
Diameter of up-leg, m
No swirling flowWith swirling flow
Gas volume distribution of RH degassing vessel
Velocity distribution of RH degassing vessel
CONCLUSIONS
Water model experiments verified that the gas bubbles maybe moved toward the central zone of up-leg of RH vessel in the swirling flow.
The numerical results showed that a swirling flow may be produced and extended into the vacuum chamber in case that rotating magnetic field is applied in up-leg. The maximum of gas volume fraction moves toward the center zone of the up-leg.
The larger circulation flow rate can be obtained in RH degassing vessel with the effect of swirling flow.
Thank you!
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