ANNUAL REPORT 2005ccc.illinois.edu/s/2005_presentations/08_bgt... · 2005. 5. 31. · Case Studies: 3-D analysis of Nucor mold • Comparison between heat fluxes of 2.5 and 4 MW/m2

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ANNUAL REPORT 2005Meeting date: June 1, 2005

Sami Vapalahti, David Hodgson, Xiangyu Dai, Jianwei Hu & Brian G. Thomas

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

Thermal analysis of CC mold and Calibration of CON1D

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

Acknowledgements• National Science Foundation

– Grant NSF-GOALI DMI 01-15486• 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, especially B. Zhao

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Introduction to CON1D• 2-D steady heat conduction in mold• 1D transient conduction and solidification in shell:

simulation domain

n 1i

MoldShell

Interface

∆x

solid shell liquid shell

z

x

qsh qint

Vc

Heat fluxHeat flux

Peak nearmeniscus

Copper Moldand Gap

Liquid Steel

1.0123

400

200

top ofmold

23 mm

4

0

Mold Exit

600

Heat Inputto shell insidefrom liquid(q )

Water Spray Zone

Meniscus

Narrow face(Peak near mold exit)

SolidifyingSteel Shell800

Wide face(Very little superheat )

int sh

Heat Removedfrom shell surfaceto gap(q )

(MW/m )2 (MW/m )2

∆x

Vc

i

x

z

22*

2 steel

steel steel steelkT T TCp k

t x T x∂∂ ∂ρ

∂ ∂ ∂∂ = + ∂


CON1D – features special analysis of interface phenomena

mold

liquidflux

V

solidflux

d dd

velocityprofile

T

shell

V

temperatureprofile

equivalentlayer foroscillation marks

k k ksolid

solid

c

fsol

TsT's

moldThotc

solid

liquid

liquid

eff

eff

T

z

x

Ts

dairkair

dsolidksolid

dliquidkliquid

deff keff

1/hrad

Ts Tsol ≥ Tmold Tfsol≥

Tmoldrcontact

Tfsol Ts’

Mass balance:

0

liquiddslag csolid solid liquid c osc

slag

Q VV d V dx V d

ρ×

= + +∫

Heat transfer:

( )int gap s moldq h T T= −

• Mass balance and heat transfer in the interfacial gap:

3


CON1D - Applications

steel propertiessteel properties

spray zone variablesspray zone variables

mold flux propertiesmold flux properties

oscillation marks parametersoscillation marks parameters

cooling water propertiescooling water properties

mold geometrymold geometry

temperaturestemperatures

mold and TCsmold and TCs

sheel surface and interiorsheel surface and interior

cooling watercooling water

shell thicknessshell thickness

heat flux leaving the shellheat flux leaving the shell

Mold frictionMold friction

flux layer thickness & fractureflux layer thickness & fracture

simulation parameterssimulation parameters

casting conditionscasting conditions

CON1D

input output

ideal mold taperideal mold taper


CON1D – example output (Algoma Steel WF-I case)

0

2

4

6

8

10

12

14

0 200 400 600 800 1000

Shel

l Thi

ckne

ss (

mm

)

Distance below meniscus (mm)

CaseI_WF SolidusCaseI_WF Liquidus

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

-200 0 200 400 600 800 1000 1200

Hea

t Flu

x (M

W/m

2)


CaseI_WF:Gap Heat FluxCaseI_WF:Water Heat Flux

0

50

100

150

200

250

300

350

400

-200 0 200 400 600 800 1000 1200

Tem

pera

ture

(C)


CaseI_WF:Hot FaceCaseI_WF:Cold FaceShell thickness

Mold Temperature

Mold Heat flux

4


-2

0

2

4

6

8

10

12

0 200 400 600 800 1000

Endw

all D

efle

ctio

n (m

m)


CaseI_WF: shell shrinkage(Depenaar)CaseI_WF: Mold distortion

CaseI_WF: total slag thicknessCaseI_WF: half extra length

CaseI_WF: ideal taper

Ideal Mold Taper



800

900

1000

1100

1200

1300

1400

1500

1600

0 2000 4000 6000 8000 10000 12000 14000

She

ll Te

mpe

ratu

re (

C)


CON1D: Shell Temperature

CaseI_WF

Surface temperature in mold and spray zones


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University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • BG Thomas 9M. Langeneckert, MS Thesis, 2001M. Langeneckert, MS Thesis, 2001

TC prediction (useful for validation) needs calibration with 3-D model

• Example 3-D mold section analysis for offset


Offset Calculation

sect w-w

sect t-tcold

hot

MOLD#2 NARROWFACE

Mol

d te

mpe

ratu

re [

o C]

Position in mold from cold side [mm]

4.0 mmoffset

Thermocouple location,

Temp = 99 oC

25

45

65

85

105

125

145

165

185

0 10 20 30 40

3D Ansys section t-tCON1D at thermcoouple CON1D section w-w3D Ansys section w-w

-18 -9 0 9 18 27

45

TCOLD

THOT

q=1.75 MW m-2

hw= 45 kW m-2 K-1

Tw = 25 o C

km= 364 W m-1 K-1

hfin = 55.6 kW m-2 K-1

all [mm], {dm=27, dch=18 wch =5, Lch=13.5}

thermocouple

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Case Study: Algoma funnel mold

• CON1D calculation for more accurate boundary conditions for hot and cold faces

• ANSYS calculations to investigate different cases:– Case 1: No thermocouple hole present in domain.– Case 2: Thermocouple hole included in domain.– Case 3: Thermocouple hole and the cooling effect

of the TC wire are both modelled in the domain.– Other cases: show that mold thickness variations

due to funnel have negligible effect on hotface and TC temps.

• Offset calculations with CON1D considering ANSYS case 2


Algoma: model domains

Thermocouple holeThermal expansion slots

Hot Face

Cold Face

Water Channel (bored holes)

Cross section of the mold

Domain for cases 2 and 3

Domain for case 1

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28.31Water temperature (°C)

35.7748Water tube heat transfer coefficient (kW m-2K-2)

1.704Heat Flux (MW m-2)

800Depth below meniscus (mm)

8.7 m/sWater Velocity in bored holes

Perfectly insulatedRemaining faces of model

14mmDistance of thermocouple from hot face

372 W m-1K-1Thermal conductivity of copper

Simulation Conditions (Case 3)

Algoma: 3-D mold temperaturesTC

TC Temperature (base of TC hole):132.7°C (case 1)138.95°C (case 2 & 3)


Algoma Mold Temp.: Case 3

Temperature profiles along different paths, thermocouple hole with thermocouple wire

0

20

40

60

80

100

120

140

160

180

200

0 20 40 60 80 100

Distance from hotface (mm)

Tem

pera

ture

(C)

Path 1Path 2Path 2Path 3Path 3Path 4

TC (point B)

Bottom of cooling water hole (N,I)

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• The difference in temperature profiles at 110, 400 and 800mm below meniscus

• Correlation between hotface temperature and heat flux

Case Studies: Algoma

Comparison of Temperature profiles from hotface to base of thermocouple hole at different depths

0

50

100

150

200

250

300

350

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Distance from hotface (mm)

Tem

pera

ture

(C)

110mm below meniscus400mm below meniscus800mm below meniscus

Comparison of heat flux against temperature of hotface

150

170

190

210

230

250

270

290

310

330

350

1.50E+06 2.00E+06 2.50E+06 3.00E+06 3.50E+06

Heat flux (W)

Tem

pera

ture

(C)

Max tempMin TempLinear (Max temp)Linear (Min Temp)


Small air gap between TC bead and mold greatly lowers TC temperature

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

160.00

0.001 0.01 0.1 1

Air gap size (m m )

Tem

pera

ture

(C)

Maintaing close contact between TC and mold wall is important

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• CON1D assumes rectangular cooling channels -> find way to match temperature with a round cooling channel (for same heat flux)

• Method found: – match the area of the cooling channels:

Acircle (14mm diameter) = Arectangle (12.4x12.4mm)– Keep same distance from hotface– Decrease mold thickness to 33mm


CaseI_WF CaseIV_WF


Thermocouple hole no conduction ANSYS Path

4 Temp P3 Temp

P 2 Temp

P 1 Temp

P 194.95 K 195.11 F 196.45 A 197.21

Q 130.67 L 130.68 G 132.17 B 138.95

R 81.093 M 78.787 H 79.974 C N/A

S 44.589 N 38.345 I 39.299 D N/A

T 42.46 O 42.638 J 42.697 E N/A

CON1D CaseI_WF CaseIII_WF CaseIV_WF

Hot Face 190.5 195.8 195.4

Cold Face 75.7 81.0 80.6

Heat Flux ANSYS CaseIV_WF 14 mm CaseIV_WF 12.10 mm

1.704 MW/m2 139.95 131.10 139.82


CON1D matches ANSYS for 3-D mold temperature calculations, so long as the mold thickness is decreased to 33.0 mm (from a range of thicknesses around funnel up to 105mm).

Offset = 1.9mm (meaning that TCs in CON1D should positioned at 12.1 mm below the hotface, which is 1.9mm closer to the hotface than actually occurs in the caster).

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Case Studies: Nucor

• ANSYS calculations to investigate different cases:– Constant Qhot and copper conductivity

• Q = 2500 and 4000 kW/m2 :– Temperature dependent conductivity of

copper– Qhot a function of distance below meniscus

• Offset calculations with CON1D considering ANSYS cases 1 and 3


Case Studies: 3-D analysis of Nucor mold

• Comparison between heat fluxes of 2.5 and 4 MW/m2

FEA Model part

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Temperature profiles along different paths

Case Studies: Nucor

Path I

Path II

Path IV

Path III

Path I

Q = 4000 kW/m2Q = 2500 kW/m2


Difference between constant and temperature dependent Kcopper

Case Studies: Nucor

)50(601355 −−= TKcopper

%45.0%100*37.124

37.12481.123=

−

• Difference in thermocouple temperatures:

Case 1 and 3 temperatures along path 1

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Q as a function of Z coordinate

Case Studies: Nucor

Path I

Path IV

Case 4

Case 5


Case Studies: Nucor

• Using the same boundary conditions as in case 3• The effect of changing K taken into account in

ANSYS• Thermocouple hole was not taken into account in

ANSYS calculation

CON1D: offset is -0.3mm

123.85125.97123.81Temperature

CON1D (15.3mm)CON1D (15mm)ANSYS (15mm)Case(distance from hotface)

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Conclusions• CON1D can be used to optimize and design a casting machine

and to inspect possible problems in production• Calibration of CON1D needs 3D thermal analysis to define the

offset, which was performed for 2 production casting molds• When defining the offsets:

– It is reasonable to neglet temperature dependence of thermal conductivity of copper

– The thermocouple hole should be included in the 3D simulation model– Copper near to the mold coldface far from the cooling channels has little

effect on the temperature profile between the hotface and cooling channel, so may be neglected in 3-D calculations

– With offsets, the simple CON1D model predictions of mold and thermocouple temperatures are quite close to the 3-D model

Documents

ANNUAL REPORT 2005ccc.illinois.edu/s/2005_presentations/08_bgt... · 2005. 5. 31. · Case Studies: 3-D analysis of Nucor mold • Comparison between heat fluxes of 2.5 and 4 MW/m2