Scaling of the Cathode Region of a Long GTA Welding Arc. P. F. Mendez, M. A. Ramirez G. Trápaga, T. W. Eagar Massachusetts Institute of Technology August 23, 2000. Motivation. The arc is an essential component of a math model of the welding process
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Scaling of the Cathode Region of a Long GTA Welding Arc
P. F. Mendez, M. A. Ramirez
G. Trápaga, T. W. Eagar
Massachusetts Institute of Technology
August 23, 2000
200 A, 10 mm, Argon
unknown characteristic values
BC for order of OMS
Real values (200 A, 10 mm)
unknown characteristic value
unknown characteristic values
Typical welding arc
Morrow & Lowke.1993. 1D theory for
Delalondre & Simonin.1990. 1D.
Chen, David, Zacharia, 1997
CATHODE AND ANODE FALLS
the electric sheats of electric arcs. (anode
modeling high intensity arcs inclu-
model interaction between the
and cathode falls).
ding non equilibrium description of
and the weld pool in GTA. Free
the cathode sheath.
surface changing with time
Zhu & Lowke.1992. Treats cathode
Kim, Fan, Na. 1997. 2D
boundary layer and arc column as
Chen & Zacharia, 1991.
GTA, cathode influence
Current thermionic emission
Analysis of the electrode tip
and free surface. No
angle and geometry of the
assumption on Jc.
Tekriwal, Mazunder.1988.2D analytical
GTA weld pool.
Mckelliget & Szekely.1986
Cram, 1983. Focussing
model for heat source (pointed tip).
Choo, 1990. Couple between
cathode and anode
on the energy balance of
Convection at anode by means of heat
arc and weld pool. Deformation
transfer coefficient, properties constant
Sui & Kou, 1990. 2D,
of the pool.
Effect of the tip geometry
Hsu & Pfender,1983. Detailed
shielding gas, nozzle,
model for the cathode region
Westhoff, 1989. 2D arc model
specifying current density at anode.
deformation of weld pool. Small
changes in Jc changes T fields.
Dawson, Bendzak, Mueller, 1997
Pradip, Yogadra, Rama, 1995
Fluid flow and Heat Transfer in a
3D, heat transfer, fluid flow in GTAW
twin cathode DC furnace. Exp.
with non-axisymetric b.c.’s. Maxwell
messurments in lab. modeling furnace
equations, uses buoyancy, surface tension
and electromagnetic forces.
ARC COLUMN MODELING
Qian, Farouk, Mathasaran, 1995
McKelliget & Szekely, 1986. 2D, DC approximate
BASED ON PHYSICAL PRINC.
Fluid flow and heat transfer in
boundary conditions. Jc=65MA/m
B.C.’S APPROXIMATED OR
EAF, 2D, DC
Goldak & Moore. 1986. Finite ele-
ment method. Describes the source.
McKelliget & Szekely, 1983
Kovitya & Cram, 1986. 2D, LTE
2D arc model, coupling pool
MHD, boundary conditions assumed.
Lowke 1980. 2D continuity
and arc models.
Kovitya & Lowke, 1985. 2D, uses
energy, naturla convection.
properties theoretically calculated.
Hsu, Etemadi, Pfender, 1983. 2D
. Extends Lowke’s
MHD eqs. with b.c’s experimentally
McKelliget & Swzekely, 1981.
,odel to incorporate Lorentz’s for-
determined. Anode and cathode
Heat transfer & Fluid flow in
ces and electron drift enthalpy.
excluded. Jc assumed with a gaussian
Allum, 1981. 2D Assumes current
Ramakrishan & Nou. 1980.
and velocity in gaussian profiles.
Dinulesca & Pfender, 1980
lowke, 1979. 2d momentum and en
2D, semianalytical model.
Includes magnetic, viscous and
Analysis of the boundary
ergy eqs. Natural convection.
Radial vel. field assumed.
layer in high intensity arcs
Lowke, 1979. 1D, analytical
Chang, Eagar, Szekely. 1979. Velo-
model for arc voltage, electric
city fields calculated analytically
Ushio, Szekely, Chang, 1980
field and plasma velocity.
using Lorentz’s forces.
2D model, assuming parabolic
Glickstein, 1979. 1D, analytical. Radial
current density distribution,
variations of temperature and J. No plas-
Squire 51: isothermal, point force
Maecker 55: e.m. force approx
Shercliff 69: point current
Yas’ko 69: dimensional analysis
2=Welding (Laminar flow).
3=EAF (turbulent flow).
2A=B.C.(anode and cathode
2B=Coupled arc and weld
2C=Geometry effects in
2AB= ANODE AND