Thermo-fluid Analysis of Helium cooling solutions for the HCCB TBM

1
Thermo-fluid Analysis of Helium cooling solutions
for the HCCB TBM

• Presented By Manmeet Narula
• Alice Ying, Manmeet Narula, Ryan Hunt and M.
  Abdou
• ITER TBM meeting
• UCLA May 10-11 2006

2
Outline

• Thermo-fluid analysis of first wall cooling
  strategies for HCCB TBM sub-modules.
• Introduction to SC/Tetra by CRADLE Co Ltd.
• Results from preliminary design activity for the
  first wall helium cooling system
• Steps toward developing an Integrated Modeling
  capability for TBM design.
• Coupling of SC/Tetra thermo-fluid analysis with
  ANSYS thermal stress calculations

3
HCCB sub-module cooling solution
First wall cooling channel
HCCB TBM sub-module
First wall cooling system with 16 channels
Helium at 8 MPa 573K at a flow rate of 0.32 kg/s
Helium flow path
4
Design Analysis Approach
Fix CAD model .MDL model
CAD model
CADthru
.MDL file format input to SC/Tetra preprocessor
Thermo-fluid Analysis Velocity Temperature
Pressure in fluid domain Temperature in solid
domain
SCTPre SCTsolver SCTpost FLDUTIL
SC/Tetra
.cdb file format to input geometry and
temperature load for ANSYS
Thermal Stress Analysis Stress and Strain in the
solid domain
ANSYS
Transient and steady state thermal stress Analysis
5
SC/Tetra by CRADLE

• SC/Tetra is a CFD system designed specifically
  for CAE activities for systematic product design.
• Versatile and Robust CAD interface (CADthru)
• A fast and efficient hybrid mesh generator
• High speed optimized flow solver with parallel
  processing capabilities
• In built post processor with state of the art
  data interpretation and visualization tools
• Ability to interface with commercial FEA codes
  (ANSYS, NASTRAN, IDEAS) for multi physics
  analysis
• Widely used in the automotive industry.

6
SC/Tetra Features

• Turbulence models
• Standard k-e
• RNG k-e
• Various low Re models for accurate simulation of
  near wall regions
• Models for fluid solid conjugate heat transfer
  analysis
• Turbulent heat transfer enhancement at the
  interface (log law)
• Phase change heat transfer
• User defined surface and volumetric heating (with
  spatial and temporal variation)
• Variable properties for the fluid and solid
  (properties change with time, temperature, flow
  conditions)
• Models for diffusion of species
• Models for radiation heat transfer

7
Helium flow analysis in HCCB sub-module SC/T

• Model comprises inlet and exit manifolds and
  first wall channels.
• Computational domain includes first wall Be layer
  (2mm), The RAFS structure and Helium coolant.
• Compressible flow model is used for helium flow
  with the RNG k-e model to calculate the transfer
  coefficients.
• A constant heat flux of 0.3 Mw / m2 is imposed on
  the first wall Be surface during the simulation.
• The helium stream is input at 0.32 Kg/s at a
  pressure of 8 MPa and temperature of 573 K.

8
Helium flow analysis in HCCB sub-module SC/T

• Turbulent heat transfer condition is used at the
  fluid solid interface. No thermal contact
  resistance is applied at the RAFS-Be interface on
  the first wall.
• Adiabatic conditions are used at the interface
  between the RAFS and the surroundings. (Heat is
  only transferred to the He coolant)
• Initial temperature of 573 K is applied in the
  entire domain.
• A total of 3 million elements are used in the
  analysis.
• Two layers of prismatic elements are placed in
  the fluid domain within 1mm separation from all
  solid surfaces for proper calculation of the
  turbulent heat transfer coefficient.
• The simulation is run until steady state is
  reached (when solution residuals fall below a pre
  decided tolerance)

9
Helium flow model with inlet manifold design A
Velocity distribution contours in the inlet and
exit manifold
Helium inlet at 8 MPa 573K at a flow rate of 0.32
kg/s
10
Automatic hybrid mesh generation based on the
Advancing Front method. Octree specification is
used as the intermediate interface between the
model and the mesh to control the mesh density
and quality
Prismatic elements are added at the wall
boundaries to ensure accurate capture of boundary
layers
11
Top view Cross section cut in the middle of
helium flow channels Inlet manifold design A
Front view Velocity distribution is not uniform
in the cooling channels
Helium inlet at 8 MPa 573K at a flow rate of 0.32
kg/s
12
Temperature distribution in the ferritic steel
structure as a result of heat transfer between
the first wall Be layer and the helium coolant
Temperature distribution in the first wall Be
layer
Surface heat flux on first wall 0.3 Mw / m2
13
Helium flow model with inlet manifold design B
Velocity distribution contours in the inlet and
exit manifold
Helium inlet at 8 MPa 573K at a flow rate of 0.32
kg/s
14
Temperature distribution in the first wall Be
layer
Velocity distribution in first wall cooling
channels (cross sectional view) Inlet manifold
design B
15
Velocity distribution in the helium flow
circuit Manifold design B
Helium inlet at 8 MPa 573K at a flow rate of 0.32
kg/s
16
Temperature distribution on the Be layer surface
exposed to surface heat flux. Inlet manifold
design A
Temperature distribution on the Be layer surface
exposed to surface heat flux. Inlet manifold
design B
Incident surface heat flux 0.3 Mw / m2
17
Coupled analysis of thermal flow and thermal
stress

• The CFD analysis model created from the available
  CAD geometry for SC/T is used for the FEA
  analysis by ANSYS. (SC/T uses a node based finite
  volume method. The nodal field and the mesh can
  be used by the ANSYS FE model)
• Nodal temperature field in the solid domain is
  calculated by SC/T. This is used by ANSYS as the
  temperature load condition
• The tetrahedral mesh and model definitions in the
  solid domain are selectively exported to ANSYS
• The first order tetrahedral elements used in the
  thermo-fluid analysis by SC/T are converted to
  higher order 10 node elements before exporting to
  ANSYS. The temperature at the new mid nodes is
  interpolated from the solution field. (FLDUTIL)
• The coupled thermal stress analysis can be steady
  state or transient

18
Next steps

• Analyze the complete flow path. (Expected
  elements 12 million)
• Steady state thermo fluid - thermal stress
  analysis using SC/T- ANSYS CFD-FEM system
• Transient thermo fluid thermal stress analysis