Experimental Study of Free GaInSn Jet in M-TOR

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Experimental Study of Free GaInSn Jet in M-TOR

• Xiaoyong Luo (UCLA)
• Presented at APEX Electronic Meeting
• February 5, 2002

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OUTLINE

• Introduction
• Experimental Facility
• Description of Test Article
• Magnetic Field of the Flux Concentrator
• Numerical Simulation
• Conclusions

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Experimental Facility

• 1. Magnetic Torus Liquid Metal MHD flow test
  facility (MTOR)
• 24 electromagnets arranged in a magnetic torus
  geometry, a 3400A/180V DC power supply, and a 16
  liter actively pumped Ga-In-Sn flow loop
• At a maximum current of 3400A, the field strength
  is about 0.6T at inboard
• 2. A Magnetic field concentrator is added into
  the facility (M-TOR) to increase the local field
  strength
• 3. Flow meter diagnostic

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Main Test Article Description

• 1. The test article is composed of 3 sections
• (1) A nozzle to provide a 5mm round jet
• (2)A transparent enclosure to prevent Ga
  oxidation
• (3)A cone-shape receiver to minimize splashing
• 2. Experiments have been conducted in two test
  articles configurations
• a circular version
• a rectangular version

Unit mm
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Flux Concentrator Assembly

• The concentrator assembly includes a pair of
  large iron circle disks (not shown), which grasp
  the flux and redistribute it into a small iron
  block
• The field strength depends on the distance
  between the pair

Unit mm
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Magnetic Field Strength inside the Flux
Concentrator

• The magnetic field increases as the current
  passing through the coils increases
• A Gauss meter is used to measure the field
  strength at 7 locations
• The maximum magnetic field is 1.1T
• The maximum gradient of the magnetic field is
  10T/m

Note Distance means distance away from the edge
of the concentrator
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Video 1 for Round Test Article

• Most of the view is blocked by the iron flux
  concentrator. Only flow outside the edge of the
  concentrator can be seen.
• The Maximum Magnetic Field is 1.1T( at the
  midplane of the concentrator)
• A gradient exists between the inside and outside
  of the concentrator. A gradient of 33T/m is
  detected

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Video 2 for Rectangular Test Article

• The Maximum Magnetic Field at the midplane is
  0.9T at 2600A
• The gradient is 10T/m
• Slots were cut in the iron concentrator along the
  gradient region to provide jet deflection
  measurements
• The jet location is indicated by the bright spot
  (jet can not be seen)

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Numerical Simulation

• Governing Equations

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Numerical Simulation

• Numerical Methods

Key Points
(1) An iterative computation to Ohms law was
applied and a Poisson equation of the scalar
potential was adopted in the numerical procedure.
(2) Two-order central difference scheme was used
(3) VOF method was used to track free surface
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Computational Results

• Ga inlet velocity is10m/s
• A constant magnetic field of 0.9T is assigned for
  the first 5cm, followed by a field gradient of
  10T/m for the rest of 10cm
• Computation domain is 15cm ? 2cm?6cm
• ( about 70,000 meshes)

3-Dimensional Velocity Profile
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X-direction Velocity Contours
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Conclusions

• 1. Numerical simulation predicts a strong MHD
  effect. Jet deflects more than experimental
  observation. Near-term effort is to resolve this
  discrepancy.
• 2. Diagnostics for measuring jet deflection will
  be improved