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Experiments on the magnetic field influence on gas-liquid metal two-phase flows. Chaojie Zhang, Sven Eckert, Gunter Gerbeth Forschungszentrum Rossendorf D-01314 Dresden, Germany Sino-German Workshop on Electromagnetic Processing of Materials Shanghai, China, 11 th -12 th , October, 2004. - PowerPoint PPT Presentation
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Institute of Safety ResearchMHD department
Experiments on the magnetic field influence on gas-liquid metal two-phase flows
Chaojie Zhang, Sven Eckert, Gunter Gerbeth
Forschungszentrum Rossendorf
D-01314 Dresden, Germany
Sino-German Workshop on Electromagnetic Processing of Materials Shanghai, China, 11th-12th, October, 2004
Institute of Safety ResearchMHD department
Motivation
Background
• numerous applications of magnetic fields and bubble-driven flows in metallurgy
Our interest
• influence of external magnetic fields on the flow fields:
gas bubbles and the induced liquid motions
Institute of Safety ResearchMHD department
Measurements of local flow properties
Difficulties
• opaqueness, high temperature, poor wettability, chemically aggressiveness
Our approach
• application of the ultrasound Doppler velocimetry (UDV)
DOP2000 (model 2125, Signal Processing SA )
Institute of Safety ResearchMHD department
Ultrasound Doppler Velocimetry (UDV)
Pulse-echo method
information about the position
time of flight measurement
information about velocity
Doppler relation
(c - sound velocity, fD - Doppler frequency, f0 - ultrasound frequency)
ctx2
D
0
c fv
2 f
Institute of Safety ResearchMHD department
Ultrasound Doppler Velocimetry (UDV)
Advantages
• spatial-temporal velocity information
• non-intrusive method
Prerequisites
• ultrasound transmission• acoustic coupling• reflecting particles
Liquid metal applicationsMercury (Takeda, 1991. Nucl. Eng. Design. Vol. 126)
Gallium (Brito et al, 2001. Exp. Fluids. Vol. 31)
Sodium (Eckert & Gerbeth, 2002. Exp. Fluids. Vol. 32)
GaInSn (Cramer & Eckert, 2004. Flow Meas. Instrum. Vol. 15)
PbBi, CuSn, Al (Eckert & Gerbeth et al, 2003 Exp. Fluids. Vol. 35)
Institute of Safety ResearchMHD department
Test problem: bubble-driven flow
LDA
US Transducer
Present experiments:bubble driven flow in water and glycerin UDV & LDA measurement
Q=178mm3/s, 85% glycerin
UDV: (channel bubbly flow)
T.Wang: Chem. Eng. J., Vol. 92
Y.Suzuki: Exp. Therm Fluid Sci., Vol. 26
Institute of Safety ResearchMHD department
0.1 1 10 10010-4
10-3
10-2
10-1
100
term
ianl
bub
ble
velo
city
[m/s
]
equivalent bubble diameter [mm]
Haberman & Morton results in tap water Kubota results in 85% glycerin UDV results in tap water UDV results in 85% glycerin
Test problem: UDV results validation
0.00 0.02 0.04 0.06 0.08 0.10 0.12-0.02
0.00
0.02
0.04
0.06
Vel
ocity
[m/s
]height [m]
LDA results UDV results
single bubble rising velocity in stagnant liquids
LDA and UDV measured liquid velocity distributions along bubble chain centerline
Institute of Safety ResearchMHD department
Bubble motion in a liquid metal columnin a longitudinal D.C. magnetic field
coil 1
coil 2
US transducer
GaInSn
• GaInSn (melting point 10°C)
• singular Ar bubbles(de = 4...8 mm)
• longitudinal D.C. magnetic field
(Bmax = 0.3 T)
• magnetic interaction parameter N
ratio between electromagnetic and inertial force (N = 0 ... 1.3)
2el TN B L /( u )
Institute of Safety ResearchMHD department
Bubble terminal velocity in GaInSn (B=0)
e
l e
gd2u
d 2
water GaInSn mercury
Density 998 6361 13610
Surface tension
0.073 0.533 0.482
Dynamic
Viscosity9.8e-4 2.2e-3 1.55e-3
Mendelson equation:
Y.Mori: J. Heat. Transfer. Vol. 99
K. Schwerdtfeger: Chem. Eng. Sci., Vol. 23
1 2 3 4 5 6 7 8 910 2010
100
1000
u T [
mm
/s]
de [mm]
Mendelson equation for GaInSn Mendelson equation for mercury UDV measured results in GaInSn data from Mori et al. (1977) in mercury
Institute of Safety ResearchMHD department
160 140 120 100 80 60 400
50
100
150
200
250
300
1
2
3
4
5
6
78
9
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6061
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A
B
C
D
E
F
G
HI
J
K
L
M
N
O
PQ
R
S
T
UV
W X
Y
Z
AAAB
AC
AD
AE AF
AG
AH
AI
AJ
AK
AL
AM
AN
AO
AP
AQAR
AS
AT
AUAV
AW
AXAY
AZ
BA
BB
BCBD
BE
BF
BG
BH
BI
BJ
BK BL
BM
BNBO
BP
BQ
BR
BS
BT
a
b
c
de
f
gh
i
j
k
l
m
n
o
p q
r
s
t
u
v
w
x
y
z
aaab
ac
ad
ae
af
ag
ahai
aj
ak
alam
an
aoap
aq
ar
as
atau
av
aw
ax
ay
az
ba
bb
bc
bd
be
bf
bg
bh
bi bj
bk
bl
bm
bn
bo
bp
bq
br
bs
bt
B=0.19Tb
ub
ble
ve
loci
ty [
mm
/s]
depth [mm]
Bubble rising velocity evolutions in GaInSn
160 140 120 100 80 60 400
50
100
150
200
250
300
B=0
bu
bb
le v
elo
city
[m
m/s
]
depth [mm]
Institute of Safety ResearchMHD department
The magnetic field influence on the ensemble-averaged bubble velocity evolutions
160 140 120 100 80 60 40 20 00
50
100
150
200
250
300b
ub
ble
ve
loci
ty [
mm
/s]
depth [mm]
B=0 B = 0.19 T
Institute of Safety ResearchMHD department
Bubble drag coefficient modifications by the magnetic field
2egd
Eo
0.01 0.1 1 100.7
0.8
0.9
1.0
1.1
1.2C
D /
CD(N
=0
)
N
Eo=2.2 Eo=2.5 Eo=3.4 Eo=4.9 Eo=6.6
Institute of Safety ResearchMHD department
Bubble velocity oscillation frequency and amplitude modification by magnetic field
0.02 0.1 1 30.7
0.8
0.9
1.0
1.1
St /
St(
N=
0)
N
Eo=2.2 Eo=2.5 Eo=3.4 Eo=4.9 Eo=6.6
St = fde/uT.
0.02 0.1 1 3
0.6
0.7
0.8
0.9
1.0
1.1
A/A
(N=
0)
N
Eo=2.2 Eo=2.5 Eo=3.4 Eo=4.9 Eo=6.6
Institute of Safety ResearchMHD department
The magnetic field influence on the bubble wake
B=0
B0
A risinggas bubble
Wake region
US transducer
Bubble Eo=5.7
Institute of Safety ResearchMHD department
Magnetic field influence on the liquid velocity distribution in the container meridional plane
-50 -25 0 25 500
50
100
150
200
Radius [mm]
He
igh
t [m
m]
-50 -25 0 25 500
50
100
150
200
-35.0-30.0
-25.0
-20.0
-15.0
-10.0
-5.00
0
5.00
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.055.0
60.0
65.0
Radius [mm]
Q=20sccm
Institute of Safety ResearchMHD department
Summary
• UDV was validated for the capacity in the relatively low gas flow rate gas-liquid metal two-phase flow measurements.
• The static longitudinal magnetic field was found to have a damping influence on the single bubble non-steady motion by modifying the bubble wake structure trailing behind.
• Liquid metal flow driven by the bubble swarm in the meridional plane showed that the static longitudinal magnetic field elongated the flow structures along the field line direction and damped the re-circulating flow region near the free surface.
Institute of Safety ResearchMHD department
Acknowledgement
The research is supported by the Deutsche
Forschungsgemeinschaft (DFG) in form of the
SFB 609 “Electromagnetic Flow Control in
Metallurgy, Crystal Growth and Electrochemistry”.
This support is gratefully acknowledged by the
authors.