Liquid metal flow under inhomogeneous magnetic field
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Liquid metal flow under inhomogeneous magnetic
field O. Andreev, E. Votyakov,A. Thess, Y. Kolesnikov
TU Ilmenau, Germany
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ElectromagneticBrake (EMBR)
magnet system
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Main goal
1. Smooth meanvelocity profile
Avoid flow instability
Avoid sources of instability
2. Brake generated and introduced velocity fluctuations
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Experimental setup
y
permanentmagnet
honeycomb
Plexiglas cover blocks
Bz magnetic field
Vivesprobe
potentialprobe
In- Ga -Sn
outletdiffuser
inletcontractor
N
S
lx
top viewly
side view
lx
N
S
30 mm
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Permanent magnet
Channel: S = 210 cm L = 90 cm
Coordinate system
Liquid metal: GaInSn
General view of test-section
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M-shape velocity profile
0,25
0,5
-105 -75 -45 -15 15 45 75 105
-50
-25
0
25
50
0,5
Y, mm
X, mm
zyx BjF ~
maxB
Bz
/jBV
Flow
0,25
B
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Governing parameters
Reynolds number:
Re=U0H/ Re<15000
Hartmann number:
Ha=B0H(/)1/2 Ha=400
MHD interaction parameter:
N=Ha2/Re N>40
U0 < 35cm/s, B0=0.5T, H=2cm
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Flow
x= - 106 mm - 29
0
20
0
0,01
0,02
0,03
0,05
0,06
0,07
0,08
-50 -40 -30 -20 -10 0 10 20 30 40 50
X, mm
0E
Ey
(b)
-0,5
0
0,5
1
2
2,5
3
3,5
-50 -40 -30 -20 -10 0 10 20 30 40 50 Y, mm
0EEy
(a)
Streamwise velocity in the middle plane of channel
potential velocimetry Re 4000
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U
Streamwise velocity in the middle plane of channel
ultrasound velocimetry Re 4000magnet
flow
flow
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Decay of velocity fluctuations under the external magnetic field
Mag
net
Flow
Re =4000I.
turbulence suppression
region
II.vorticalregion
III.wall jet region
u´/U0%
5.0
7.5
2.5
10
0-5 -2.5 0 2.5 7.55 10
on the axes
12.5
near walls
15
B
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Accuracy of
potential velocimetryin the region of
inhomogeneousmagnetic field
is ?!
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Principles of potential velocimetry
zy BUy
j
from
Ohm’s law
streamwisevelocity
z
y
z B
j
yBU
1
measurablevalues
physical
ERRORof the potential velocimetry
y
x
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electrical current in the middle
plane
spanwiseJy
electricalcurrent
negative values of el.current
positivevalues of el.current
positivevalues of el.current
z
y
z B
j
yBU
1
overestimatedvalues of velocity
overestimatedvalues of velocityunder
estimatedvalues
directnumericalsimulation
byE. Votyakov,
E. Zienike
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voltmeter
flow
potential difference between the side walls
dyjBBH
Qy
zz 11
flow rate through the channel integral estimation of
error
movable electrodes onthe side walls
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0
0.5
1
1.5
2
2.5
3
3.5
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6x/H, dimensionless streamwise coordinate
Re=271640145312661179099207105051180413102Magnetic field
overestimatedvalues of flow rate
overestimatedvalues of flow rate
underestimated
valuesQB
H
z
flow
potentialdifference
flow rate
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-0.5
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
-50 -30 -10 10 30 50
X/H=0streamwise
velocity
0U
UDOP2000
potentialprobe
Comparison of ultrasound and potential velocimetry
flowRe 4000
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0
0.5
1
1.5
2
2.5
3
3.5
4
-50 -30 -10 10 30 50
X/H=-3streamwise
velocity
0U
U
DOP2000
potentialprobe
Comparison of ultrasound and potential velocimetry
flowRe 4000
Vivesprobe
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0
1
2
3
4
5
6
7
8
9
-50 -30 -10 10 30 50
X/H=2streamwise
velocity
0U
U
DOP2000
potentialprobe
Comparison of ultrasound and potential velocimetry
flowRe 4000
Vivesprobe
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0
1
2
3
4
5
6
7
-50 -30 -10 10 30 50
X/H=6streamwise
velocity
0U
U
DOP2000
flowRe 4000
Vivesprobe
Comparison of ultrasound and potential velocimetry
potentialprobe
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0
0.5
1
1.5
2
2.5
3
3.5
-50 -30 -10 10 30 50
X/H=8streamwise
velocity
0U
UDOP2000
flowRe 4000
Vivesprobe
Comparison of ultrasound and potential velocimetry
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Summary remarks• The laboratory flow was investigated in the
following range of the governing parameters:
Ha = 400, Re<15000, N>10.
• Potential probe qualitatively reproduces velocity field within the region of two magnet gaps in streamwise direction.
• Vives probe is strongly influenced by the external electric potential and could be applied on the distance which exceeds 5-6 gaps of magnet.