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

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

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**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**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**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**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**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.**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**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.**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)**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**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**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**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**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**Temperature distribution in the first wall Be layer**Velocity distribution in first wall cooling channels (cross sectional view) Inlet manifold design B**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**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**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**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 Next steps