flow control by tailored magnetic fields
DESCRIPTION
Context, Basic Ideas, Some Examples Sino-German Workshop on Electromagnetic Processing of Materials (EPM) Shanghai University, Oct. 11-13, 2004 G. Gerbeth Forschungszentrum Rossendorf (FZR), Dresden, Germany. Flow Control by Tailored Magnetic Fields. Magnetic Fields: - PowerPoint PPT PresentationTRANSCRIPT
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Flow Control Flow Control by Tailored Magnetic Fieldsby Tailored Magnetic Fields
Context, Basic Ideas, Some Examples
Sino-German Workshop on Electromagnetic Processing of Materials (EPM)
Shanghai University, Oct. 11-13, 2004
G. Gerbeth
Forschungszentrum Rossendorf (FZR), Dresden, Germany
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Magnetic Fields: Contactless influence on Processes and
MaterialsAttractive R&D topic for the future
Powerful research programs in China and Germany: Cooperation between Chinese and German teams
(serious basis exists already) Exchange of students, Ph.D.’s, postdoc’s Joint R&D projects, joint industrial projects (?)
Support by Sino-German Center for Research Promotion(founded by NSFC and DFG) is gratefully acknowledged
Introduction: Sino-German Workshop on EPM
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Basic and applied studies on Magnetohydrodynamics (MHD):- 20 years tradition at FZR- 10 years tradition at Dresden University (TUD)- Local network in Dresden (IFW, Uni Freiberg, FhG, MPI)- Traditional cooperation and Twinning Agreement with
Institute of Physics Riga (Latvia)
Since 2002: Collaborative Research Centre SFB 609 at TUD
“Electromagnetic flow control in metallurgy, crystal growth and electrochemistry”
supported by DFG supposed to last 11 years with ~ 1.7 Mio €/a
Introduction: MHD in Dresden (Germany)
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Electrically conducting fluids: liquid metals, semiconductor melts, electrolytes
MHD = NSE + Lorentz Force
where
Context
BjtrfL
),(
)( BvEj
Volume force : - nice tool to play with the flow- can be arranged as needed- contactless action, perfectly controllable- several applications, industrial requests
Lf
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Up to now: Forward Strategy – What are the changes if some magnetic field is applied?
Known magnetic field actions: DC fields: Flow damping AC-fields, low frequency: stirring and pumping AC-fields, high frequency: Heating and melting, levitation
MHD Catalogue
Necessary: Transition to inverse approach1) Which flow is desirable?2) Which Lorentz force can provide this?3) How to make this Lorentz force?
Note: flow field often not the goal, just some intermediate agent
Basic Idea: Tailored magnetic field systems
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Why now?
1) Strong request from applied side for smart solutions with low effort (Tesla cost money!)
2) powerful community for optimization, control theory, inverse strategies
3) new computer capabilities
4) MHD catalogue is well filled
5) new level of velocity measuring techniques for liquid metal MHD flows (liquid metal model experiments up to T 400°C)
6) new level of experimental tools for superposition of AC and DC magnetic fields
Basic Idea: Tailored magnetic field systems
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
PbBi bubbly flow at T 270°C
Velocity measuring technique (example)
75 100 125 150 175 200 2250
50
100
150
200
250
300
350
400
bubble
liquid velocity
velo
city
[mm
/s]
depth [mm]
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Experimental platform for combined AC and DC magnetic fields
MULTIMAG
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Examples for partly going the inverse way
1) Industrial Cz-growth of single Si crystals
2) Float-zone crystal growth
3) Industrial Al investment casting Dr. Eckert
4) Melt extraction of metallic fibers
5) Seawater flows
6) Electromagnetic levitation Dr. Priede
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Industrial Cz-growth of single Si crystals
Goals: - larger diameters (200 300)- stable growth process- homogeneous oxygen distribution
Solution: AC fields for flow driving, DC fields for reduction of fluctuations
Combined fields installed at Wacker Siltronic
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Float-zone crystal growth
Usual HF heater gives double-vortex in molten zone
Concave phase boundary is bad for the growth of single crystals
of intermetallic compounds
Goal: modified flow field in order to change the solid-liquid phase boundary
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Float-zone crystal growth
Solution: secondary coil with phase shift acting as a pump
Realization at IFW Dresden
Parameters to adjust: Current amplitude and frequency, vertical distance between coils, C1, R1
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Float-zone crystal growth
The principle action of such a two-phase stirrerModel experiments demonstration
Single coil double coil double coil upwards pumping downwards pumping
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Optimum: distance crystal radius
Float-zone crystal growth
Numerical simulations: electromagnetic fields, flow, temperature field
Example: Variation of the vertical distance of the coils
h = 1 mm h = 3 mm h = 5 mm
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Float-zone crystal growth
Growth of NiSi5Pumping action of the double inductor:
downwards upwards
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Float-zone crystal growth
Standard float-zone with double inductor
HoNi22B2C Fe87.5Si12.5 YNi2B2C
Ni95Si5
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Extraction of steel fibers Extraction of steel fibers in an open industrial facilityin an open industrial facility
Melt extraction of metallic fibres
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Principle of the process
Melt extraction of metallic fibres
• rapid quenching• almost all materials
(intermetallics, too)
• Diameter > 100 mikron• Too broad distribution of fibre diameters
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Melt extraction of metallic fibers
Magnetic stabilization of: the free surface (global DC field) + the meniscus oscillations
(ferromagnetic edge)
Model experiment Results: red – no magnet with SnPb green – with magnetic control
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Summary
Flow control by magnetic fields: nice tool to modify velocity fields
inverse approach: challenging task Several industrial requests, short bridge to
applications
Essential tools: numerical simulations new class of velocity measuring techniques for
liquid metals „cold“ model experiments
Attractive basis in China and Germany
Right time for a Sino-German Workshop
Forschungszentrum Rossendorf
Sino-German Workshop on EPMShanghai, Oct. 11-12, 2004
Outlook for 2005
Joint 15th Riga and 6th PAMIR International Conference on
Fundamental and Applied MHDRiga (Latvia), June 27 – July 1, 2005
http://www.ipul.lv/pamir
German-Chinese Workshop in Dresden: to be discussed