Flow in a Funnel Mold - Continuous Casting Consortiumccc.illinois.edu/s/2007_Presentations/02_RIETOW_Bret_Flow... · – Investigate the effect of casting ... Processing Simulation

ANNUAL REPORT 2007UIUC, June 12, 2007

Bret Rietow (MS Student) &Brian G. Thomas

Department of Mechanical Science and Engineering

University of Illinois at Urbana-Champaign

Flow in a Funnel Mold

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • BG Thomas 2

Objectives

– Model fluid flow in a funnel mold caster– Compare steel flow with water models– Investigate the effect of casting speed

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


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


Velocity in nozzle

Front View Side View


Port outlet velocity

Side ViewFront View

Back Flow


Jet Characteristics

<4%Back Flow Zone Percentage

1.62Port-to-bore Ratio

79.4Vertical Jet Angle (degrees)

1.14Jet Speed (m/s)

3.6Casting Speed (m/min)

Good uniform spread of flow leaving ports despite a large port to bore ratio.

Steep downward jet, resulting in a slower flow on the top fluid surface.

A high casting speed can be run with this nozzle without EMBR.


Model Formulation: including steel shell

• 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

VC

vVMassSink

*..

**..

**

ρ

ρ

−=

−=


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)


Domain Width (mm)

1200Mold Length (mm)

132Mold Thickness (mm)

984Mold Width (mm)

Case 2-SParameter/Property


Model Validation (top surface velocity)

-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]

Ho

rizo

nta

l Ve

loc

ity

to

wa

rds

SE

N [

m/s

]

• Horizontal Velocity at Top Surface WF Centerline


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

Distance from Center [m]

Do

wn

wa

rd V

elo

cit

y, V

z [m

/s]

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


Funnel Mold Design

Funnel Taper through Mold(not to scale; all units in mm)

900

300

Mold Top40

8

Steel

Mold

10893.19090

160240325

Mold Top

900 mm below Top to Mold Bottom Surface

170148.39090

Mold Thickness (all units in mm)

Nozzle


Funnel Mold Model

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 2: Port Effective Height ×Thickness (mm × mm)

2500Domain Length (mm)


Domain Thickness (mm)

1450 (top)1414 (domain bottom)

Domain Width (mm)

1200Mold Length (mm)

90Mold Thickness at narrow face (mm)

1450Mold Width (mm)

3.6 m/minCasting Speed

Y

Z

0

-3.2

-3

-2.8

-2.6

-2.4

-2.2

-2

-1.8

-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2 Solidifying steel shell greatly affects shape of liquid pool


Flow Pattern details

Centerline

3.6m/min steel caster


Surface velocity details

Uniform flow towards SEN (idealized symmetric steady flow pattern)

Rounded SEN allows smooth streamlined flow and penetration into gap between SEN and WF

Funnel effect is small (flow behavior similar to parallel mold)



Flow Pattern details

Velicity vectors and streamlines in WF Centerline


X

Z

-0.6 -0.4 -0.2 0

-3.2

-3

-2.8

-2.6

-2.4

-2.2

-2

-1.8

-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

1 m/s

X

Z

-0.6 -0.4 -0.2 0

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

Note: Lower recirculation zone extends deep into caster


X

Z

-0.6

-0.6

-0.4

-0.4

-0.2

-0.2

0

0

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

X

Z

-0.6

-0.6

-0.4

-0.4

-0.2

-0.2

0

0

-1.4 -

-1.2 -

-1 -

-0.8 -

-0.6 -

-0.4 -

-0.2 -

0

0.2

X

Z

-0.6

-0.6

-0.4

-0.4

-0.2

-0.2

0

0

-1.4 -

-1.2 -

-1 -

-0.8 -

-0.6 -

-0.4 -

-0.2 -

0 0

0.2 0

X

Z

-0.6

-0.6

-0.4

-0.4

-0.2

-0.2

0

0

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

Overall Flow Pattern (CL comparison)

Qualitatively similar flow patterns (water model has lower NF impingement)

3.6 m/min 4.8 m/min3.6m/min Water model 4.2m/min


0

0.1

0.2

0.3

0.4

0.5

0.6

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

Distance from Centerline, X [m]

Ve

loc

ity

Ma

gn

itu

de

, U

mag

[m

/s]

3.6 Water

3.6 Steel

4.2 Steel

4.8 Steel

SEN

Shell Front

Narrowface

Centerline

Surface velocity(towards SEN, across width near top surface)

Water model produces much lower surface speeds

Liquid slag on Top Surface

3.6 m/min

4.8 m/min

Increasing casting speed linearly increases surface velocity

3.6 m/min Water model

10 mm


Downward velocity(down centerline near NF)

Water model produces excessive speeds low in caster

-3.5

-3.25

-3

-2.75

-2.5

-2.25

-2

-1.75

-1.5

-1.25

-1

-0.75

-0.5

-0.25

0

0.25

0.5

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

Downward Velocity, Uz [m/s]

Do

ma

in H

eig

ht,

Z [

m]

3.6 Water

3.6 Steel

4.2 Steel

4.8 Steel

Liquid Steel Top Surface

0.6 m

3.6 m/min

4.8 m/min

Increasing casting speed increases velocity more towards end of lower recirculation region



0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

-0.05 -0.045 -0.04 -0.035 -0.03 -0.025 -0.02 -0.015 -0.01 -0.005 0


Do

wn

war

ds

Vel

oci

ty,

Uz [

m/s

]

3.6 Water

3.6 Steel

4.2 Steel

4.8 Steel

Shell Front Centerline

Wideface

Downward velocity(through thickness 1m below meniscus)

Water model under-predicts speed in upper recirculation region(lack of shell resistance to push flow upwards)

3.6 m/min

4.8 m/min

Increasing casting speed linearly increases velocity


1 m

0.6 m


0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

-0.05 -0.045 -0.04 -0.035 -0.03 -0.025 -0.02 -0.015 -0.01 -0.005 0


Do

wn

wa

rds

Ve

loc

ity

, U

z [

m/s

]

3.6 Water

3.6 Steel

4.2 Steel

4.8 Steel

CenterlineShell Front

Wideface

Downward velocity(through thickness 2m below meniscus)

Water model produces higher speed estimates in lower recirculation region

3.6 m/min

4.8 m/min

Increasing casting speed linearly increases velocity

2 m

0.6 m



0

0.05

0.1

0.15

0.2

0.25

0.3

-0.05 -0.045 -0.04 -0.035 -0.03 -0.025 -0.02 -0.015 -0.01 -0.005 0


Do

wn

wa

rds

Ve

loc

ity

, U

z [

m/s

]3.6 Water

3.6 Steel

4.2 Steel

4.8 Steel


Wideface

Downward velocity(through thickness near NF)

Water model produces excessive speeds low in caster (missing shell)

3.6 m/min

4.8 m/min

Increasing casting speed increases velocity linearly

3 m

0.6 m



-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

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


Do

wn

wa

rds

Ve

loc

ity

, U

z [

m/s

]

3.6 Water

3.6 Steel

4.2 Steel

4.8 Steel


Narrowface

Downward velocity(across width 3m below meniscus)

Water model produces excessive speeds low in caster (missing shell)

3.6 m/min

4.8 m/min

Increasing casting speed increases velocity linearly

3 m



Top-Surface Standing Wave Profile

SEN

Narrowface

-8.00

-7.00

-6.00

-5.00

-4.00

-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

-0.8 -0.75 -0.7 -0.65 -0.6 -0.55 -0.5 -0.45 -0.4 -0.35 -0.3 -0.25 -0.2 -0.15 -0.1 -0.05 0


Su

rfa

ce

He

igh

t D

efo

rma

tio

n, ∆

h [

mm

]

3.6 Water

3.6 Steel

4.2 Steel

4.8 Steel

Steel-slag interface height along wideface centerline approximated using fixed surface pressures

3.6 m/min

4.8 m/ming

ppheight

fluxsteel

mean

∗−−

=)( ρρ

Higher standing waves in steel than water model


Conclusions: Steel Caster / Water Model

• Water model and steel both have generally similar classic double-roll flow patterns. The funnel effect is small.

• Water model underpredicts velocity in upper mold, including 32% low top surface velocity (0.34 vs 0.48 m/s), and less surface turbulence.

• Steel shell provides resistance to flow (~50% drop in cross section area), so “pushes” more fluid to the surface, increasing recirculation velocities.

• Water jet penetrates deeper than steel jet, impinging ~0.13m lower on NF, due to lack of shell taper restricting downward flow.

• Far below top surface, downward steel flow is nearly uniform (at the casting speed), so all particles penetrating this far are eventually trapped. Water model sends flow disturbances far into strand: producing more eddies in low-velocity regions and extending lower recirculation zone.


Conclusions: Effect of Casting Speed

• Increasing casting speed has little effect on single-phase flow pattern and jet impingement location (-0.835 m below the top surface). Lower recirculation region is extended further down the strand.

• Velocity increases almost linearly with casting speed. Maximum surface velocity increases with casting speed, from 0.48 m/s (3.6 m/min) to 0.57m/s (4.8 m/min)

• Increasing casting speed produces quadraticallyincreasing top surface wave height and profile

• The highest point of the standing wave occurs near the meniscus and slopes downward to the SEN.


Acknowledgements

• Continuous Casting Consortium Members (Algoma, Baosteel, Corus, Delavan, Labein, LWB Refractories, Mittal Riverdale, Nucor, Postech, Steel Dynamics)

• National Science Foundation– GOALI DMI 05-00453 (Online)

• National Center for Supercomputing Applications (NCSA) at UIUC

• Fluent, Inc.• Former UIUC researchers: L. Zhang and J.

Aoki

Documents

Flow in a Funnel Mold - Continuous Casting Consortiumccc.illinois.edu/s/2007_Presentations/02_RIETOW_Bret_Flow... · – Investigate the effect of casting ... Processing Simulation