Modeling Velocity Flow in Funnel Mold Casters

1

ANNUAL REPORT 2005Meeting date: June 1, 2005

Bret Rietow (M.S. Student) &Brian G. Thomas

Department of Mechanical & Industrial EngineeringUniversity of Illinois at Urbana-Champaign

Modeling Velocity Flow in Funnel Mold Casters

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • B Rietow2

Objectives

• Compare two different thin-slab caster nozzle designs– Examine velocity outlet characteristics

• Examine fluid flow in a funnel mold caster– Draw comparisons with traditional parallel mold thin-slab

casters– Investigate the effect of varying parameters (eg. casting

speed) on the fluid flow profile– Analyze particle trajectory/entrapment in a funnel mold

2


Nozzle 1: Geometry and Operating Conditions

Casting Speed = 4.8 m/min(slab size = 90x1450 mm)

Inlet velocity (down ward) = 1 m/sSteel density = 7000 Kg / m3Steel viscosity = 0.006Kg/m.sPort Dimensions= 25 x 77 mm

All Dimensions are in mm

D115

22

124

AA

R11

Section AA

320

790

1283

D80

45 deg angle at portFront View Side View


Nozzle 2: Geometry and Operating Conditions

Casting Speed = 3.6 m/min(slab size = 90x1450 mm)

Inlet velocity (F.S.) = 1.56 m/sSteel density = 7000 Kg / m3Steel viscosity = 0.006Kg/m.s

All Dimensions are in mm

Front View Side View

D80

1165

392

143

155 28

3


Velocity Contour Comparison

Front View Side View Front View Side View

Nozzle 1 Nozzle 2


Lower Nozzle Velocity Contours

Zoomed Bottom View

Nozzle 1

Nozzle 2

4


Nozzle 1: Velocity Vectors (nozzle bottom)

Front View Side ViewBack Flow

Back Flow


Nozzle 1: Back Flow At Port Outlet

Outlet Port

P0P3P6P9

5


Nozzle 2: Velocity Vectors (lower nozzle)

Side ViewFront View

Back Flow


Jet Characteristics

<4%<4%Back Flow Zone Percentage

1.621.24Port-to-bore Ratio

79.432Vertical Jet Angle (degrees)

1.143.25 (2.4 at 3.6 m/min casting speed)

Jet Speed (m/s)

3.64.8Casting Speed (m/min)

At Ports(Nozzle_2)

At Ports(Nozzle_1 )

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Comparison of Two Nozzles

• Velocity increases midway down nozzle due to the drop in cross-sectional area, especially in Nozzle 1

• The outlet ports of Nozzle 1 have two regions of backflow (both top and bottom of ports). The bottom backflow zone is likely due to the nozzle’s elongated well shape

• Nozzle 1:– Smaller ports than nozzle 2, producing a higher velocity jet.

• Nozzle 2:– Good uniform spread of flow leaving ports despite a large port to bore ratio– Steeper downward jet, resulting in a slower flow on the top fluid surface. A

higher casting speed can be run with this nozzle without the presence of EMBR.


Mold Parameters

• CON1D used to predict shell thickness• Mass and momentum “sinks” used at fluid

boundaries to simulate solidification– Sinks are a function of shell curvature

• Standard k-epsilon turbulence model• FLUENT solves N.S. equations for steady,

single phase flow

θ

Vcasting

Vn

ρsolid

ρliquid

A1

A2

A3

C.V (Volume=V)

x

z

Vt

izc

zc

VVC

vVnkMomentumSi

VCvVMassSink

*..**

..**

ρ

ρ

−=

−=

7


Model Validation

• Comparison to previous work performed by QuanYuan on a parallel mold thin-slab caster

984mm 132mmFree-Slip Bounary

Casting Speed:25.4mm/s

zy

x

Shell Boundaries

Jet

2400mm

934mm 80mm

Pressure B.C. at Bottom

Liquid-pool

7.98 × 10-7Fluid Kinematic Viscosity (m2/s)

25.4Casting Speed (mm/s)

127SEN Submergence Depth (mm)

32Bottom nozzle Port Diameter (mm)

75 × 32 (inner bore)

Nozzle Port Height × Thickness (mm × mm)

2400Domain Length (mm)

132 (top)79.48 (domain bottom)

Domain Thickness (mm)

984 (top)934.04 (domain bottom)

Domain Width (mm)

1200Mold Length (mm)

132Mold Thickness (mm)

984Mold Width (mm)

Case 2-SParameter/Property


Model Validation (cont.)

-0.09

-0.04

0.01

0.06

0.11

0.16

0.21

0.26

-0.08 0.02 0.12 0.22 0.32 0.42

Distance from Center [m]

Hor

izon

tal V

eloc

ity to

war

ds S

EN [m

/s]

• Horizontal Velocity at Top Surface WF Centerline

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Model Validation (cont.)

-0.27

-0.22

-0.17

-0.12

-0.07

-0.02

0.03

0.08

0.13

0.18

0.23

0.28

0.33

0.38

0.43

0.48

-0.64 -0.54 -0.44 -0.34 -0.24 -0.14 -0.04 0.06 0.16 0.26 0.36 0.46 0.56


Dow

nwar

d Ve

loci

ty, V

z [m

/s]

• Downward Velocity along WF Centerline, 0.5m from top surface


Funnel Mold Design

Dimensions:Narrow Face: 90 mmWide Face: 1450 mmMold Length: 1200 mmMax. Funnel Width: 170 mmSEN Submergence: 265 mm

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Funnel Mold Design

Mold Top

90

900 mm below Mold Top Bottom Surface

90 148.3 170

90 90 93.1 108

Mold Thickness [mm]

Mold Thickness [mm]

900

300

40

8

Funnel Taper through Mold (not to scale) All units are in mm

Top


Funnel Mold Model

• 3.6 m/min casting speed• Nozzle 2 results will be used as mold fluid inlet data

170Mold Thickness in top funnel region (mm)

8.57 × 10-7Fluid Kinematic Viscosity (m2/s)

3.6Casting Speed (m/min)

265SEN Submergence Depth (mm)

201.53 × 28Nozzle Port Effective Height ×Thickness (mm × mm)

2500Domain Length (mm)

90 (top)50.84 (domain bottom)Domain Thickness (mm)

1450 (top)1414 (domain bottom)Domain Width (mm)

1200Mold Length (mm)

90Mold Thickness at narrow face (mm)

1450Mold Width (mm)

Case 3.6Parameter/Property

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Funnel Mold: W.F. Centerline Velocity Plots


Funnel Mold: Top Surface Pressure

• Pressure contour at the top surface of the mold– Higher pressures near the meniscus and the nozzle

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Pressure Height

Funnel Mold: Top Surface WF Centerline Pressure

gppheight

fluxsteel

mean

∗−−

=)( ρρ

• Knowing the pressure, top surface height can be approximated using:

Nar

row

Fac

e

SEN


Funnel Mold: Velocity Near Top Surface along WF Centerline

• Velocity along WF Centerline at 10 mm below top surface (boundary conditions imposed at top surface yield zero velocity)

Velocity along WF Centerline, 10 mm below Top Surface

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

-0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0

Distance from center [m]

Velo

city

[m/s

]

Nar

row

Fac

e

SEN

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Funnel Mold: Velocity Near Top Surface


Funnel Mold: Velocity at Bottom Surface along WF Centerline

Bottom Surface Velocity along WF Centerline

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

0

-0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0


Velo

city

[m/s

]

Nar

row

Fac

e

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Funnel Mold Observations

• Classic double-roll flow pattern is observed• Top surface velocity reaches a maximum of 0.35 m/s,

within reasonable limits (although on the high side)• Funnel effect is small; no steady state eddies are

observed in funnel region• There is no recirculation zone at the bottom pressure

outlet. Particles may be more likely to become trapped in the strand.


Future Research Work

• Further postprocess data to investigate differences between a funnel mold and a parallel wall thin-slab mold

• Obtain data for 4.8 m/min casting speed, and draw comparisons between the 3.6 m/min casting speed

• Introduce particle/inclusion tracking into the model– Determine likelyhood of particle entrapment– Track particle pathways

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Acknowledgements

• Continuous Casting Consortium at UIUC (Nucor, Postech, LWB Refractories, Accumold, Algoma, Corus, Labein, Mittal Riverdale)

• National Center for Supercomputing Applications (NCSA) at UIUC

• Fluent, Inc., CFX, UIFLOW (P. Vanka)• Other Graduate students (L. Zhang, J. Aoki)• Brian Thomas

Documents

Modeling Velocity Flow in Funnel Mold Casters