Experimental Study of Free GaInSn Jet in M-TOR Xiaoyong Luo (UCLA) - - PowerPoint PPT Presentation

Experimental Study of Free GaInSn Jet in M-TOR

Xiaoyong Luo (UCLA)

Presented at APEX Electronic Meeting

February 5, 2002

• 1-

OUTLINE

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

• 2-

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

Ga Inlet Flow Meter Ga Outlet Argon Gas Supporter Circle disk Concentrator Iron block Concentrator

• 3-

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

5mm Nozzle Cone- shape Transparent area

Unit: mm

• 4-

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
• n the distance between the

pair

Slots

Iron Block Unit: mm

• 5-

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 Maximum Point Maximum Gradient

• 6-

Video 1 for Round Test Article

• Most of the view is blocked by the

iron flux concentrator. Only flow

• utside 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

• 7-

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)

• 8-
• Governing Equations

Numerical Simulation

) ( Re 1 ) . (

→ → → → → →

× + ∆ + −∇ = ∇ + ∂ ∂ B j N U p U U t U

t B E ∂ ∂ − = × ∇

→ → → →

= × ∇ j B

      × + =

→ → → →

B U E j σ

= ⋅ ∇

→

j

) (

2 → →

× ⋅ ∇ = ∇ B U φ

Momentum Equation Maxwell’s Equations Ohm’s Law conservation law Poisson Equation

• 9-
• Numerical Methods

Numerical Simulation

→ → → +

⋅ ∇       − −         × ⋅ ∇ = ∇

n n n n

j B U ε σ φ 1 1 1

1 2

) ( ) 1 (

1 1 → → + → → +

× + −∇ + − =

n n n n n

B U j j φ εσ ε

3 1

1 1

− → → → +

≤ + − e j j j

n n n

Convergence critical (1) An iterative computation to Ohm’s law was applied and a Poisson equation of the scalar potential was adopted in the numerical procedure.

Key Points:

(2) Two-order central difference scheme was used. (3) VOF method was used to track free surface.

• 10-

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

g

5cm 10cm

T=0.9T T’=10 T/m V=10m/s

• 11-

X-direction Velocity Contours

t=0.025s t=0.02s t=0.01s t=0.015s

• 12-

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