“current results of the solidification modelling in
TRANSCRIPT
Simulation & Modellierung metallurgischer Prozesse,
Department Metallurgie, Montanuniversität Leoben 1
PFAU 9.0 | Johannes Kepler Universität Linz | 03 Nov 2014
“Current results of the solidification modelling
in continuous casting”
Dr. Alexander Vakhrushev
Simulation & Modellierung metallurgischer Prozesse,
Department Metallurgie, Montanuniversität Leoben 2
OUTLINE
Introduction
Modelling of casting process
Inclusions modelling
Liquid slag model verification
Heat transfer through the refractory
Conclusions & outlook
#3
Ladle
Tundish
Mold
Strand
Support
rolls
Stopper
Processes to simulate: continuous casting
[Wikipedia]
#4
OUTLINE
Introduction
Modelling of casting process
Inclusions modelling
Liquid slag model verification
Heat transfer through the refractory
Conclusions & outlook
#5
Results of the thin slab casting simulation
#6
METALLURGICAL AND MATERIALS TRANSACTIONS B
We got 10 pages of comments & questions
Constructive
Didn’t require a content change
Some interesting results were added
Enforced some important improvements:
Direct usage of T-dependent properties (IDS)
Reconsider heat fluxes (narrow face)
#7
Direct usage of the IDS data
Solid fraction Specific heat Thermal conductivity
# idsToOPENCAST.py IDS_data_file_name_prefix
#9
Flow / solid shell interaction
Stream lines Shell thickness
#10
Shell thickness verification: 30% of solid
Cut I
#11
Tipp: strong back flow for some designs
Pressure inlet
Velocity outlet
(fixed normal + slip)
#12
Boundary conditions to suppress backflow
Pressure inlet:
turbulentIntensityKyneticEnergyInlet, I=4%
turbulentMixingLengthDissipationRateInlet, d=0.07*D
Velocity outlet:
fixedNormalSlip with casting velocity
No back flow at all
#13
OUTLINE
Introduction
Modelling of casting process
Inclusions modelling
Liquid slag model verification
Heat transfer through the refractory
Conclusions & outlook
#14
DNS flow simulation in a tundish
#15
DNS vs. RANS flow simulation in a tundish
DNS
K-epsilon
#17
Particle flow in a tundish (DNS simulation)
#18
OUTLINE
Introduction
Modelling of casting process
Inclusions modelling
Liquid slag model verification
Heat transfer through the refractory
Conclusions & outlook
#19
Motivation: focus on the SEN region
(a) mechanisms of slag entrapment
(b) SEN refractory erosion kinetics
(c) free surface oscillation/waves
(d) patterns of turbulent jet flow
(e) sensitivity of all phenomena to SEN design
(e)
(c) (b)
(d)
(a)
#20
Governing equations of the numerical model
𝜌mixture = 𝛼melt ⋅ 𝜌melt + 𝛼slag ⋅ 𝜌slag + 𝛼air ⋅ 𝜌air
𝜇mixture = 𝛼melt ⋅ 𝜌melt ⋅ 𝜂melt + 𝛼slag ⋅ 𝜌slag ⋅ 𝜂slag + 𝛼air ⋅ 𝜌air ⋅ 𝜂air
𝜂mixture = 𝜇mixture 𝜌mixture
∇ ∙ 𝑢 = 0
𝜕𝛼𝑖𝜕𝑡
+ ∇ ∙ 𝑢 𝛼𝑖 = 0
Mixture properties:
Incompressible turbulent flow:
𝑆 surf = 𝜎𝑖𝑗 𝜅𝑖𝑗 α𝑗∇α𝑖 − α𝑖∇α𝑗
𝑖 ,𝑗
𝜅𝑖𝑗 = −∇ ∙ α𝑗∇α𝑖 − α𝑖∇α𝑗
α𝑗∇α𝑖 − α𝑖∇α𝑗 where
Scalar transport of volume fraction:
𝜕𝜌𝑘
𝜕𝑡+ ∇ ∙ 𝜌𝑢 𝑘 = ∇ ⋅ 𝜇 +
𝜇t
𝑃𝑟t,k∇𝑘 + 𝐺 − 𝜌𝜖
𝜕𝜌𝜖
𝜕𝑡+ ∇ ∙ 𝜌𝑢 𝜖 = ∇ ⋅ 𝜇 +
𝜇t
𝑃𝑟t,ϵ∇𝜖 + 𝜌𝐶1𝜖𝜖 − 𝐶2𝜖𝜌
𝜖2
𝑆𝑘
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
𝜕𝜌𝑢
𝜕𝑡+ 1 − 𝛼air ∇ ∙ 𝜌𝑢 ⊗ 𝑢 = −∇𝑝 + ∇ ∙ 2𝜇eff𝐃 + 𝜌𝑔 + 𝑆 surf
𝛼melt + 𝛼slag + 𝛼air = 1
a) b)
𝑘 (𝑚2𝑠−1)
Standard model Modified
a) b)
𝑘 (𝑚2𝑠−1)
Standard model Modified
#21
Experimental setup and simulation domain
melt slag airmelt slag air
a)
b)
c)
Simulationdomain
Outflow
Outf
low
Meniscus
a)
b)
c)a)
b)
c)
Simulationdomain
Outflow
Outf
low
Meniscus
#22
Water modelling results
1.5 m/min
#23
Simulation results / comparison with experiment
𝑢 , m s
a) b)
Flow simulation:
Comparison with the water modelling results:
Slag position / velocity vectors Velocity magnitude Stream-lines
Experiment Simulation
Time-averaged int. position
#24
OUTLINE
Introduction
Modelling of casting process
Inclusions modelling
Liquid slag model verification
Heat transfer through the refractory
Conclusions & outlook
#25
Heat transfer through refractory: motivation
Estimate heat losses through the SEN
Can it lead to the solidification at the flow stagnation zones?
when ~ 1 K of superheat
is predicted !!!
#26
Model development: ÖGI solidification benchmark
Al
Cu
symmetry
symmetry
symmetry
insulated
insulated
insulated HTC specified
solidifying shell
liquid core
#27
Model development: ÖGI solidification benchmark
finalAlp
Alfinal
Cup
Cu
Alinit
Alp
AlCuinit
Cup
Cu
TCmTCm
LTCmTCm
curve red
curve blue
Al
Cu
#28
2D solidification with the heat transfer in SEN
Mold: wall heat flux
Mel / slag interface:
HTC specified SEN / melt wall: HTC
SEN / air wall:
HTC + radiation
Simulated
Not simulated
#29
2D solidification with the heat transfer in SEN
#30
OUTLINE
Introduction
Modelling of casting process
Inclusions modelling
Liquid slag model verification
Heat transfer through the refractory
Conclusions & outlook
#31
Shell formation (DNS)
#33
Shell thickness: comparison DNS vs. RANS
RANS DNS
#34
Future work: DNS simulation of a free surface
#35
Particle simulation with 2 phase VOF
#36
THANK YOU FOR YOUR ATTENTION!