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New possibilities for velocity measurements in metallic melts S. Eckert , G. Gerbeth, F. Stefani

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New possibilities for velocity measurements in metallic melts S. Eckert, G. Gerbeth, F. Stefani Department Magnetohy - PowerPoint PPT Presentation


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New possibilities for velocity measurements in metallic melts S. Eckert , G. Gerbeth, F. Stefani Department Magnetohydrodynamics, Forschungszentrum Rossendorf P.O. Box 510119, D-01314 Dresden, Germany, http://www.fz-rossendorf.de/FWS/FWSH E-mail: [email protected]

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slide1
New possibilities for velocity measurements in metallic melts

S. Eckert, G. Gerbeth, F. Stefani

Department Magnetohydrodynamics, Forschungszentrum Rossendorf

P.O. Box 510119, D-01314 Dresden, Germany, http://www.fz-rossendorf.de/FWS/FWSH

E-mail: [email protected]

Sino-German Workshop

on Electromagnetic Processing of Materials

Oct. 11-13, Shanghai, China

slide2

Why do we need flow measurements in metallic melts ?

Knowledge about the flow field and the transport

properties of the flow

Optimisation of products, technologies and facilities

  • better understanding of the process
  • validation of CFD models
  • on-line control and monitoring
slide3

Current situation

Commercial measuring techniques for liquid metal flows are almost not available !

Reasons

  • properties of the fluid (opaqueness, heat conductivity,..)
  • high temperatures
  • chemical reactivity
  • interfacial effects
  • external electromagnetic fields
goals
Goals
  • to develop measuring techniques for liquid metal flows at moderate temperatures

 model experiments (T  300°C)

  • to extend the range of application towards higher temperatures
data of interest
Data of interest
  • flow rate
  • local velocity
  • fluctuations, turbulence level
  • flow pattern (velocity profiles, 3D-structure)
slide6

List of measuring techniques

  • Local probes(invasive)
      • Electric Potential Probe (EPP, Vives Probe)
      • Mechano-Optical Probe (MOP)
  • Ultrasonic methods(non-invasive, but need contact)
      • Ultrasound Doppler Velocimetry (UDV)
  • Inductive methods(contact-less)
      • Inductive Flowmeter (IFM)
      • Contactless Inductive Flow Tomography (CIFT)
  • X-ray radioscopy
  • Local probes(invasive)
      • Electric Potential Probe (EPP, Vives Probe)
      • Mechano-Optical Probe (MOP)
  • Ultrasonic methods(non-invasive, but need contact)
      • Ultrasound Doppler Velocimetry (UDV)
  • Inductive methods(contact-less)
      • Inductive Flowmeter (IFM)
      • Contactless Inductive Flow Tomography (CIFT)
  • X-ray radioscopy
ultrasound doppler velocimetry udv
Ultrasound Doppler Velocimetry (UDV)
  • Takeda (1987, 1991)
  • Commercial instrument
  • standard transducers

(Tmax = 150°C)

  • Measurement of instantaneous velocity profiles
udv in liquid metals problems
UDV in liquid metals – problems
  • High temperature
  • Acoustic coupling
  • Transmission of ultrasonic energy through

interfaces (channel walls)

  • Wetting conditions
  • Availability of reflecting particles
concept of an integrated probe ii
Concept of an integrated probe II
  • Collaboration with the University Nishni-Novgorod (Russia)
  • Piezoelectrictransducer coupled on an acoustic wave guide made of stainless steel
  • Stainless steel foil (0.1 mm) wrapped axially around a capillary tube: length 200 mm, outer diameter 7.5 mm
slide12

UDV – Flow driven by RMF

Streamfunction

Vertical velocity

slide13

UDV – Flow driven by TMF

Vertical velocity

Streamfunction

slide15

UDV in CuSn/Al – Experimental Set-up

  • Rectangular alumina crucible (130  80 mm2)
  • melt depth 40 mm
  • inductive heater
  • melt temperature:

620°C (CuSn), 750°C (Al)

  • installation of the integrated sensor at the free surface of the melt
  • Doppler angle 35°
slide16

UDV in CuSn/Al – Results

Profiles obtained at two positions:

  • different signs
  • similarity of shape and amplitude

Velocity signal obtained in liquid

aluminium by up-and-down moving

of the sensor by hand

slide17

Contactless Inductive Flow Tomography (CIFT)

  • An existing flow field will modify an applied magnetic field:

B=B0+b,b~Rm B0 (Rm=µLv)

e.g. the magnetic field measured outside the melt contains information about the flow field

  • Rm ~ 10-3  b ~ O(T)

Example: crystal growth configuration

(Czochralski method)

slide18

CIFT - Basics

  • Bio-Savart‘s law
  • inverse method to reconstruct the velocity field
  • additional requirements:
    • mass conservation (div u = 0)
    • Tichonov regularization (keeps the mean quadratic curvature of the velocity field finite)
cift experiment
CIFT - Experiment
  • 48 Hall sensors

(KSY44-Infineon, resolution 1 T)

  • Mechanical stirrer (2000rpm)

max. velocity ~ 1 m/s

  • Cylinder filled with InGaSn

(D = 180 mm , H = 180 mm)

  • Magnetic field: two pairs of Helmholtz coils 10mT
cift experiment20
CIFT - Experiment

Lid with stirrer and motor

Vessel, electronic equipment

cift results
CIFT - Results

Induced magnetic field

for transverse primary

field

Induced magnetic field

for axial primary field

Reconstructed velocity field

conclusions
Conclusions
  • Several measuring techniques exist to determine the velocity field in metallic melts
  • Successful investigations are under progress to extend the application range towards higher temperatures
  • Promising new developments:
    • Ultrasound Doppler Velocimetry (UDV)
    • Contactless Inductive Flow Tomography (CIFT)
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