NASA Technical Reports Server (NTRS) 20170000384: Development of an Unstructured PDF
Preview NASA Technical Reports Server (NTRS) 20170000384: Development of an Unstructured
National Aeronautics and Space Administration Development of an, unstructured, three- dimensional material response model AIAA SciTech Conference Grapevine, TX 2017 Joseph Schulz, Eric Stern, Grant Palmer, Suman Muppidi, Olivia Schroeder, and Alexandre Martin 1 www.nasa.gov/spacetech Background High-Temperature Gases NASA Material Response Tools Surface Energy Balance In-depth physics Engineering Tools • STAB / CHAR (NASA JSC) radiation • FIAT / TITAN (NASA ARC) • Icarus (NASA ARC) mass loss re-radiation Ablating Surface convection Inform engineering models Pyrolysis Gases Research Tools conduction • PATO (NASA ARC) Decomposition Zone Material Properties • PuMA (NASA ARC) Virgin Composite Sub-structure *Not an exhaustive list 2 Motivation • Why Icarus? ▪ Three-dimensional physics modeling and complex geometries ▪ Coupling to CFD simulation ▪ Software architecture ➢ Easy to add new physics, numerics, and material property models ➢ Linking to optimization and inverse parameter estimation methods ▪ Independent of other NASA material response models ➢ Provides verification of predictions • Target Applications 3D ArcJet IsoQ ADEPT ArcJet Test Orion Compression Pad 3 Icarus Spring 2017 Winter 2017 ICARUS Version 1.0 Development Roadmap Version 2.0 Physics Models Thermal Conduction Physics Models + Decomposition Version 3.0 Thermal Conduction + Pyrolysis Gas Continuity + Pyrolysis Gas Momentum Numerical Methods + Element Conservation Physics Models Time integration Dust erosion / spallation Numerical Methods - First-order Backward Euler Linear elasticity model Implicit Time Integration - Second-order Runge-Kutta - Point relaxation Spatial integration Numerical Methods - Numerical Jacobians - Green-Gauss reconstruction AMR Gradient reconstruction Mesh Motion - Weighted least-squares Interface - Radial-basis functions GUI Verification and Validation Verification and Validation Design Toolbox Analytical Heat Conduction Orion ArcJet validation - Shape optimization Ablation Workshop Test Cases HEEET ArcJet validation - Inverse parameter estimation PICA ArcJet validation MSL Flight data - Uncertainty quantification 4 Icarus - Version 1.0 Status Indicates an external binary Data I/O and Initialization Input / Output Data Formats *Indicates a work in progress HDF5 / XDMF, CGNS, Tecplot finish Main Loop Data I/O and Post-‐processing Thermodynamics / Transport Numerics Physics Models Heat Conduction Materials Explicit Time Integration + Decomposition Icarus Tables / Polynomials First-‐order Euler + Pyrolysis gas production 2nd-‐order Runge-‐Kutta + Surface recession / ablation Gas Mixtures Icarus / NASA CEA Gradient Reconstruction Thermal Boundary Conditions Mutation++ Green-‐Gauss contour integration Isothermal Cantera Heat Flux -‐ Adiabatic -‐ Spatial / Temporal Function Utilities Test Automation Surface Energy Balance Database Creation Unit Testing Grid Deformation Integration Testing Icarus GUI Regression Testing 5 Icarus - Data Structure • Modular data structure partitions physics, numerics, and material or gas models • Organization is user friendly and extensible Blocks 1 and 2 are defined Processor 1 for different physics models Blocks can contain multiple Physics Model 1 Physics Model 2 property zones: — Material / Gas 1 — Material / Gas 2 Shared Ghost Cells — Material / Gas 3 Unstructured index ordering — interior faces / cells — boundary faces / cells Material / Gas Material / Gas Material / Gas — processor shared faces / cells Mixture 1 Mixture 2 Mixture 3 Processor 2 Model Boundary Condition 6 Icarus - Production Code • Production codes require : 1. Sufficient documentation • Web-based documentation • Uses Sphinx, a Python tool that parses in-source code documentation to create HTML and LaTeX formatted documentation 2. Verification • Automated unit and integration testing (~60% coverage currently) • Regression testing 3. Validation • Comparison to Arc Jet data (current focus of PICA validation) • Shifting focus this year to AVCOAT modeling • MSL flight data • Participation in code-to-code comparisons to understand variability in modeling assumptions and prediction uncertainty • Ablation Workshop • Relationships with research institutes and university laboratories 7 Outline • Icarus Formulation • Verification Tests ▪ Analytical heat conduction ▪ Governing equations ▪ Multi-dimensional test cases ▪ Numerical formulation • Current On-Going Work ▪ Mesh motion ▪ Surface ablation radiation mass loss re-radiation Ablating Surface convection Pyrolysis Gases conduction Decomposition Zone Virgin Composite Sub-structure 8 Formulation : Pyrolysis • Pyrolysis Modeling 1. Solve the elemental conservation equations • Requires a detailed kinetic mechanism and knowledge of material composition 2. Use empirical relationships • Measure quantities only at the virgin and fully-charred states • Use simplified kinetics • Three-component model virgin resin + binder Pyrolysis Gases gas : pseudo-volume fraction of pyrolyzing resin ; is the material porosity Decomposition Zone Virgin Composite Sub-structure : total production of pyrolysis gas 9 Formulation : Material Properties • Properties are measured for at the virgin and fully-charred states ▪ Requires linearly interpolating between two states ▪ Internal energy of the material is evaluated either as a tabular or polynomial curve-fit that is a function of temperature and pressure • Total mixture quantities are determined by weighted average using the gas mass fraction : mass fraction of the gas mixture • Thermal equilibrium and gas mixture in chemical equilibrium 10
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