Transcript MHD related activities for DCLL

MHD related activities for
DCLL
Presented by Sergey Smolentsev, UCLA
FNST MEEETING
August 18-20, 2009
Rice Room, 6764 Boelter Hall, UCLA
LAYOUT
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Assessment of DCLL IB DEMO blanket
SiC-PbLi slip phenomena
Status of “mixed convection” studies
Status of “corrosion” code development
Modeling Chinese “FCI” experiment
“Corrosion” experiment with SiC in Riga
and related activities
Assessment of DCLL IB blanket, 1
Principal DCLL DEMO IB blanket
design with He and PbLi access pipes
IB versus OB DEMO blanket:
•smaller available space
•lower heat load (the average
neutron wall load is 1.33 MW/m2)
(c)
•long poloidal path of the PbLi
flows (~2-4 m)
•significantly higher magnetic
field (10-12 T against 4-6 T)
Main focus: How high is the
MHD pressure drop?
(a)
(b)
(d)
Sketch of the IB DEMO blanket. Only 3 lower modules are shown. (a) Front view,
including the blanket modules, He and PbLi access ducts, vacuum vessel, and the TF
coil. (b) Rear view. Only the PbLi carrying elements and the TF coil are shown. (c)
He and PbLi access ducts. (d) PbLi access ducts.
Analysis:
3D MHD pressure drop
Effect of FCI on p2D in poloidal flows
Flow in the access ducts
S. Smolentsev, C. Wong, S. Malang, M. Dagher, M. Abdou,
MHD Considerations for the DCLL Inboard Blanket,
ISFNT-9, Dalian, China, 2009.
Assessment of DCLL IB blanket, 2
Summary of 3D MHD pressure drop
Ha
N
k
p3D, MPa
Blanket. Inlet manifold
26500
7000
1.5
0.49
Blanket. Outlet manifold
26500
7000
1.5
0.49
Access duct (internal). Fringing field
13250
930
0.5
0.31
Access duct (annulus). Fringing
field
26500
3750
0.5
0.14
3D flow
p3 D
1
  U m2
2
  kN
 is the local pressure drop coefficient
N is the interaction number
k is the empirical constant , 0.2  k  2
Total MHD pressure drop = 1.43 MPa < 2 MPa
(providing ~1-10 S/m)
Inlet/outlet
manifold
Flow in a fringing field
•Average NWL: 1.33 MW/m2
•Magnetic field: 10 T
•PbLi Tin/Tout=450/750C
•Velocity in a blanket duct: 0.015 m/s
•Each module: 1.4x1.4x0.5 m
•12 poloidal ducts per module, 0.2x0.2 m
•The longest access duct is 4.2 m
•5 mm SiC FCI
Assessment of DCLL IB blanket, 3
Effect of FCI electrical conductivity on MHD pressure drop in poloidal flows
P ~ 103 MPa
~ 102
~ 101
Ideal insulation
Effectiveness of the 5 mm SiC FCI as electric insulator in the
poloidal IB blanket flow in a 10 T magnetic field (Ha=26500).
•<0.1 S/m - ideal insulation
•~1 S/m - p2D~10-3 MPa
•~10 S/m - p2D~10-2 MPa
•~100 S/m - p2D~10-1 MPa
•~1000 S/m - p2D~1 MPa
•If ~100 S/m, p2D~ p3D
Our goal is to have p2D<< p3D.
Therefore, <100 S/m is required
(<1-10 S/m is desired)
Assessment of DCLL IB blanket, 4
Flow in the access ducts
MAGNETIC FIELD
(a)
(b)
Sketch of the cross-section of the PbLi access duct (a) and the
computational mesh (b).
“cold” PbLi flow in: annulus
“hot” PbLi flow out: inner duct
Assessment of DCLL IB blanket, 5
Flow in the access ducts
1.2
•No flow occurs in the
sections of the annulus
perpendicular to B
0.8
Velocity
B=4 T, =0
0.4
0
•This may cause lack of
cooling of the inner duct
-0.4
-0.8
•Pipe-in-pipe geometry
looks attractive
-1.2
-2
1.5
-1
0
1
2
y/b
Velocity
B=4 T, =10 S/m
•Turbulence (if appears)
will likely result in better
cooling
1
0.5
0
More studies for access
ducts needed
-0.5
-1
-2
-1
0
y/b
1
2
Assessment of DCLL IB blanket, 6
CONCLUSIONS
• The total MHD pressure drop is 1.43 MPa (30%)
• We are approaching the limit of 2 MPa. Special care
should be taken in case of any design modifications
• <100 S/m (5 mm FCI) is required, <1-10 S/m is desired
• Flows in access ducts need more analysis (including
possible turbulence effects) as the present studies
suggest lack of cooling. Pipe-in-pipe configuration seems
to be the best option
SiC-PbLi slip phenomena, 1
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Recent studies suggest that SiC is
not fully wetted by PbLi
Pint, B.A., More, K.L., Meyer, H.M., Distefano, J.R.: Recent
progress addressing compatibility issues relevant to fusion
environments, Fusion Science and Technology, 47, 851-855
(2005)
Morley, N.B., Medina, A., Abdou, M.A.: Measurements of
specific electrical contact resistance between SiC and leadlithium eutectic alloy, TOFE 18, San Francisco, Sep. 28 – Oct.
2, Book of Abstracts, P2.66, (2008)
Changho, P., Kazuyuki, N., Yamamoto, Y., Konishi, S.:
Compatibility of materials for advanced blanket with liquid
LiPb, TOFE 18, San Francisco, Sep. 28 – Oct. 2, Book of
Abstracts, P1.67 (2008)
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Poor wetting is direct indication of
slip phenomena
We use a parameter called “slip
length” to include the slip effect in
MHD/HT models
CORROSION OF SILICON CARBIDE FILTER IN
MOLTEN METAL
K. Sujirote and K. Goyadoolya
National Metal and Materials Technology Center
Science Park, Pathumthani 12120 Thailand
“Due to its non-wetting behavior, and excellent
resistance to corrosion and thermal shock,
corrugated silicon carbide filter is suitable for
filtering molten metal.”
SiC-PbLi slip phenomena, 2
Characterization of slip effect on MHD flow
The slip effect can affect
blanket flows in two ways:
Slip length increases
1. Reduction of MHD
pressure drop – definitely a
useful tendency
2. More unstable flows –effect
on heat and mass transfer;
not fully understood yet
S. Smolentsev, MHD duct
flows under hydrodynamic
“slip” condition, Theor.
Comput. Fluid Dyn., published
online May 19, 2009.
SiC-PbLi slip phenomena, 3
Reduction of MHD pressure drop
The slip length can vary from nanometers to microns or
even tens of microns for specially designed
superhydrophobic surfaces.
Assumption: the slip length is 1 m
OB: MHD pressure drop reduction: 2 times
IB: MHD pressure drop reduction: 3 times
Assumption: the slip length is 10 m
OB: MHD pressure drop reduction: 10 times
IB: MHD pressure drop reduction: 20 times
Along with electrical insulation, utilization of slip effect
between SiC and PbLi could be considered as another
approach to control the MHD pressure drop in DCLL.
Example: =100 S/m superhydrophobic FCI
is equivalent to =10 S/m no-slip FCI
Q: Can we engineer SiC superhydrophobic surfaces?
Superhydrophobic bio-fiber surfaces
via tailored grafting architecture by
Daniel Nystrom, et al, Chem.
Commun., 2006, 3594–3596
SiC-PbLi slip phenomena, 4
Suggested experiment to
demonstrate that slip effect does
exist by measuring the contact angle
Principal scheme
Steps towards development
of SiC-based
superhydrophobic surfaces
1. Simple demonstration
Inert gas
experiments for PbLi-SiC
2. Flow-involving experiments to
confirm directly the interfacial
slip and quantify the slip length
3. Understanding the interfacial slip
mechanisms
PbLi droplet
4. More detailed modeling of the
effect of interfacial slip on MHD
flows / HT in blanket conditions
5. Development and testing SiCbased superhydrophobic
Heated SiC substrate surfaces
SiC-PbLi slip phenomena, 5
CONCLUSIONS
• A strong effect of the interfacial slip on MHD flows (and
also as a consequence, on heat and mass transfer) can
be predicted
• Providing the slip length is of order of microns, the
reduction of MHD pressure drop can be as high as ~1020 times
• Engineering and utilizing superhydrophobic SiC surfaces
in DCLL might be an effective approach (along with
development of simple electrical insulation) to control the
MHD pressure drop
• Further analysis on qualification of slip effect on heat and
mass transfer is needed
Status of “mixed convection” studies
Linear stability analysis and
non-linear numerical
simulations demonstrate very
rich physics. We have
significantly advanced recently
in understanding mixed
convection phenomenon in
DCLL blanket conditions.
Pre-experimental analysis has
been accomplished showing
that major mixed convection
effects can be simulated in lab
conditions.
Preparation to the mixed
convection experiment is in
progress.
Status of “corrosion” code development
There are three steps envisaged in the modelling effort for the
compatibility of the ferritic/martensitic steels with the eutectic leadlithium alloy in a fusion blanket system
1.
Relatively simple and easy-to-use code, limited to the analysis of
the transport of wall material from the wall/LM interface into the
flowing liquid metal for canonical flow geometries and relatively
simple flow conditions.
This is where we are now
2.
Conversion of this code into a subroutine to be used in an
available code describing MHD, heat transport, turbulence,
buoyancy flow …. under the conditions of a fusion blanket
(HIMAG).
3.
Use of the experience gained with these codes in a new
comprehensive code system to be developed for the prediction of
the integral behaviour of a liquid metal fusion blanket.
Modeling Chinese “FCI” experiment, 1
We have unofficial collaboration with the
MHD group in China lead by Prof. Zengyu Xu
Picture of experimental MHD facilities in the
Southerstern Institute of Physics (SWIP), China.
Accepted for publication in
Magnetohydrodynamics, 2009
Modeling Chinese “FCI” experiment, 2
Dimension
Notation
Value, m
Half-width of the FCI box
b
0.023
Half-height of the FCI box
a
0.027
tFCI
0.002
Thickness of the gap
tg
0.005
Thickness of the slot
ts
0.003
Thickness of the Fe wall
tw
0.002
FCI thickness
Magnetic field
•2 mm FCI made of epoxy provides ideal electrical insulation
•Maximum magnetic field is 2 T (Ha=2400)
•Uniform B-field: 740 mm (length) x 170 mm (width) x 80 mm (height)
•Outer SS rectangular duct: 1500 mm long
•FCI box: 1000 mm long
•Pressure equalization openings: slot (PES) or holes (PES)
•Measurements: pressure drop, velocity (LEVI)
Modeling was performed under the experimental conditions
using the fully developed flow model
Modeling Chinese “FCI” experiment, 3
•Experiment shows significant
decrease in the MHD pressure drop
by FCI
•Experiment also demonstrates
better pressure drop reduction in
the PEH case compared to the PES
•The computations show much more
pressure drop reduction compared
to the experiment
How to explain the difference
between the experiment and theory?
Prof. Xu: The flow is fully
developed but the openings result
in extra currents leading to extra
high flow opposing force
Sergey: There is no way the
opening can cause such strong
currents but the flow is developing
Modeling Chinese “FCI” experiment, 4
 Modeling confirms that there is a
current loop associated with the
pressure equalization opening but
the current is too small to cause
such a high MHD pressure drop
 The pressure drop includes
p3D(due to fringing magnetic
field) and p2D. It appears that in
the experiment, p3D~ p2D.
Recommendation (experiment):
(1) to measure pressure drop in the
bulk (not in the gap)
(2) to have more measurements of
electric potential
Recommendation (modeling):
(1) to perform computations in 3D
“Corrosion” experiment with SiC in Riga
and related activities, 1
A picture of the PbLi loop with auxiliary equipment in the
Institute of Physics in Riga, Latvia.
•Starting from the last summer
we have intensive discussions
with the Institute of Physics in
Riga, Latvia (O.Lielausis,
A.Shishko) on a joint
research on SiC FCI in PbLi in
a strong magnetic field
•Other interested people: Prof.
Rene Moreau (France) and
material people from Grenoble
•Plan: Latvia – experiment,
UCLA – modeling,
Prof. Moreau – development of
a mathematical model
•Although all parties are
technically ready to start,
Latvian group looks for about
50 K a year for this experiment
“Corrosion” experiment with SiC in Riga
and related activities, 2
f1
stainless
steel
SiC
Bo
Z
Pb17Li
316L
f2
Y
Cross-section of the test-section with
the SiC plate
The main goal is to address MHD/corrosion phenomena
when a SiC sample is washed by a flowing PbLi in the
presence of a strong magnetic field.
•Outer duct: SS, 180 mm x 40 mm x 20 mm , 1.5 mm thick.
•SiC plate: 100 mm x 40 mm. The thickness is 2 to 5 mm.
•The SiC sample is fixed using 10 rectangular brackets
(shown in red) made of non-magnetic steel AISI 316 L.
•PbLi velocity: 5 cm/s.
•Magnetic field: 5 T.
•Nominal temperature of PbLi: 550C.
•Duration of the experiment: 500 hours.
•Bulk velocity is controlled by measuring the electric
potential difference. Pressure drop is measured over the
whole length of the test-section.
•In the end of the experiment the SiC sample and all 10
brackets will be extracted and carefully weighted. An
additional microscopic analysis can be performed either in
Latvia, France or US.
“Corrosion” experiment with SiC in Riga
and related activities, 3
Similar experiments on corrosion of FS in PbLi in Riga
Macrostructure of the washed samples
after contact with the PbLi flow
B=0
Corrosion rate for samples with
and without a magnetic field
B=1.8 T
From: F. Muktepavela et al. EXPERIMENTAL STUDIES OF THE STRONG
MAGNETIC FIELD ACTION ON THE CORROSION OF RAFM STEELS IN Pb17Li
MELT FLOWS, PAMIR 7, 2008
 Strong experimental evidence of significant effect of the applied
magnetic field on corrosion rate.
“Corrosion” experiment with SiC in Riga
and related activities, 4
Summary of the observations made with the
Grenoble
SEM
(Scanning
Electronic
Microscope) and with optical microscopes
(July 21, 2009).
• The main effect is an erosion of the wall
• The eroded material is transported by the
fluid flow without any re-deposition
• The grooves in the eroded wall seem to
be a footprint of periodic rolls that appear
due to instability of Hartmann layers.
Some irregularities are also present due
to 3D disturbances in the flow.
• The key mechanism might be coupling
between the hydrodynamic instability
(responsible for the rolls) and chemical
dissolution of the wall material (probably
related to an electro-migration effect).
Yves Bréchet, René Moreau and
Laurent Maniguet