Combustion Modeling using Ansys CFD - asge-national.org

1 1 2016 Ansys , 2, 2016 Ansys Confidentia lCombustion Modeling using AnsysCFDN avraj Hanspal, Stefano Orsino& Ahmad HaidariAnsysInc, Canonsburg, 2016 Ansys , 2, 2016 Ansys Confidentia l Ansys &KeyTechnologies SimulationDrivenProductDevelopment WhatisCFD? ANSYSFLUENT ANSYSS olutions CombustionModeling DPM&SprayModeling Pollutant/EmissionsModeling ApplicationTestCase(s) Summary&DemoAgenda3 2016 Ansys , 2, 2016 Ansys Confidentia l*BusinessWeek, FORTUNE Ansys -Simulation Leader FOCUSEDThis is all we product technologies in all physics areasLargest development team focused on simulationCAPABLE2,700+ 75 40 employeeslocationscountriesTRUSTEDFORTUN E 500 Industrials 96 of the top 100 ISO 9001 and NQA-1 certifiedPROVENR ecognized as one of the world s MOST INNOVATIVE AND FASTEST-GROWING COMPANIES*INDEPENDENTLong-term financial stabilityCAD agnosticLARGEST3xThe size of our nearest competitor4 2016 Ansys , 2, 2016 Ansys Confidentia l45.

2 000+CUSTOMERSGLOBALLYF luidsStructuresElectromagneticsThermalPo wer IntegritySystemsEmbedded SoftwareLeading DisciplinesAutomotiveAerospace & DefenseAcademicConstructionConsumer GoodsElectronicsEnergyHealthcareIndustri al Rotating MachineryMaterials &Chemical ProcessingSemiconductorsIndustry PresenceOur Industry Reach and Solution Offerings1,300+680+800+PEOPLEG lobal Reach2,000+ FROM CHANNEL PARTNERS5 2016 Ansys , 2, 2016 Ansys Confidentia lBreadth of TechnologiesStructural Mechanics:From Linear Statics Fluid Mechanics: From Single-Phase Flows Electromagnetics: From Low-Frequency WindingsSystems:From Data SharingTo High-Speed ImpactTo Multiphase CombustionTo High-Frequency Field AnalysisTo Multi-Domain System Analysis6 2016 Ansys , 2, 2016 Ansys Confidentia lOur Vision: Simulation Driven Product DevelopmentConceptPhysicalPrototypeProdu ctionSimulation-DrivenProduct DevelopmentDetailed Design7 2016 Ansys , 2, 2016 Ansys Confidentia lStreamlined Workflow StrategyWorkbench End-To-End Solutions In a Unified Environment8 2016 Ansys , 2, 2016 Ansys Confidentia lANSYS, Technologies Ansys design, develops, markets and globally supports a comprehensive range of engineering simulation software Proven software technologies for Fluid Dynamics (FLUENT, CFX) for CFD Structural Mechanics Acoustics Electromagnetics Multiphysics Specialized tools, including Ansys Icepak (thermal/flow for electronics) Ansys nCode DesignLife (for fatigue)

3 EmagAcousticsStructuralCADI mportParametric SimulationDesign ExplorationMeshingPost-processingFluid10 2016 Ansys , 2, 2016 Ansys Confidentia lAdvanced CFD DesignXplorerMeshingMechanicalDesignMode lerANSYS WorkbenchANSYS WorkbenchA common environment integrating Ansys tools for multi-disciplinary CAE simulation11 2016 Ansys , 2, 2016 Ansys Confidentia lWhat is CFD? Flow simulation, or Computational Fluid Dynamics(CFD), is the science of predicting fluid flow, heat transfer, mass transfer, chemical reactions, and related phenomena by solving the mathematical equations (normally PDE s) Three Step and and analysisGeometry and MeshingResults Analysis12 2016 Ansys , 2, 2016 Ansys Confidentia lComputational Fluid Dynamics (CFD) Fluid mechanics that uses numerical methods and algorithms Solve, analyze problems that involve fluid flows Flow characteristics Heat and mass transfer Chemical reactions, etc.

4 Fundamental basis Solves Navier-Stokes Equations, numerically To conserve mass, momentum, energy, species Ansys CFD solvers based on Finite Volume MethodExptSim13 2016 Ansys , 2, 2016 Ansys Confidentia lANSYS FluentWidest array of Modeling capabilitiesAccurate capabilities to simulate a wide range of phenomena: aerodynamics, combustions, hydrodynamics, mixtures of liquids/solids/gas, particles dispersionsCustomizable numerical modelsCustomizable to extend the capabilities to your specific CFD needs, and include your "secret ingredients" like material properties, simulation models, solver speed and HPC scalabilityA fast solver: industry-leading multi-processor solver technologies ensure that you get the fastest time to solutionFluidsCourtesy Speedo Courtesy Dyson Ltd. Courtesy Astec, 2016 Ansys , 2, 2016 Ansys Confidentia lConsolidated Tools for CAD, Geometry, Meshing &Post-ProcessingIntegration in Ansys Workbench Flexible Workflows Connect to other Simulation tools for Multi-Physics Analysis Parameterization for OptimizationANSYS FLUENT WorkflowFLUENTS etup/Solve/PostDesignModelerOr SpaceClaimANSYS MeshingPlatformCFD-PostANSYS WorkbenchANSYS CAD Plug-inCAD SystemGeometry MeshingPost-ProcessingSetupSolveCADG eometry CADM eshingSetupSolvePost-Processing15 2016 Ansys , 2, 2016 Ansys Confidentia lModelingFlow Physics in FLUENT16 2016 Ansys , 2.

5 2016 Ansys Confidentia lCFD MethodologyProblem Identification Define goals Identify domainPre-Processing Geometry Mesh Physics Solver SettingsSolve Compute solutionPost Processing Examine resultsUpdate ModelGasGasDomain of interestRiserSolids volume fraction contours (5 micronparticles)Courtesy: Fuller CompanyCyclone17 2016 Ansys , 2, 2016 Ansys Confidentia lMotivation for Modeling Reacting Flow Devices are very complex Complex geometry, complex BCs, complex physics (turbulence, multi-phase, chemistry, radiation,..), complex systems, .. Tool to gain insight and understanding Predictions of flow field and mixing characteristics Temperature field Species concentrations Particulates and pollutants Reduce expensive experiments Eventually design!18 2016 Ansys , 2, 2016 Ansys Confidentia lReacting Flow ApplicationsANSYS CFD contains models which are applicable to a wide range of homogeneous and heterogeneous reacting flows Furnaces Boilers Process heaters Gas turbines Rocket engines IC engine CVD, catalytic reactionsImportance More Efficient (Energy Efficiency) Cleaner (Pollutant Regulations) Safer (Safety Regulations)Environment & Emissions controlPropulsion & EnginesMicros & NanosBiomedicine &BiochemistryClimate change & Energy sustainabilityFire & Fire protectionBurnersBoilersIC EnginesFired HeatersGas FlaresGas Turbine Combustors19 2016 Ansys , 2, 2016 Ansys Confidentia lKey Results using Ansys SpaceClaimDirect Modeler, the model was ready for meshing and simulation in only four hours.

6 Engineers increased primary air entrainment from 36 percent to 52 percent. This generated a stable flame with nearly complete Combustion , high levels of efficiency and low levels of carbon in Action Whirlpool chose Ansys SpaceClaimDirect Modeler, which enables easy geometry cleanup and generation of closed volumes required for CFD. Engineers then used Ansys Fluent to perform Combustion simulation using the EDC Combustion and SST turbulence Reduced Burner Model Prep Time by 90 percent with Ansys SpaceClaimNew-GenerationDesigning a Better Burner Whirlpool Brazil relies heavily on simulation to design gas burners for freestanding ranges, built-in ovens and cooktops. Engineers required a tool to prepare models for simulation so that they could quickly explore a range of designs to come up with the best burner that would meet all design time by 35%Reduced time to analysis by 90% This application demonstrates the time-and cost-savings that can be achieved by enabling simulation engineers to quickly and easily prepare design geometry for simulation, as well as how an efficient design can be determined using simulation.

7 Pablo FilgueiraRodeiroSenior Manager Simulation-Based DesignWhirlpool Corporation20 2016 Ansys , 2, 2016 Ansys Confidentia lCFD Models involved in Reacting FlowsCombustionApplicationsTurbulence ModelingPollution ModelingRadiationModelingCombustion ModelingModelingMultiphase Flows21 2016 Ansys , 2, 2016 Ansys Confidentia lRole of Turbulence in Reacting System Flows encountered in most of the Practical Reacting Systems are turbulent Reactions and Turbulence affect each other Turbulence-chemistry interaction Turbulence is modified by flames Through flow acceleration, modified kinematic viscosity Modified turbulence alters the flame structure Enhanced mixing and chemical reactions (through temp fluctuations) Mixing time scale ( F) relative to chemical time scale ( chem) An important parameter to decide whether the reaction is mixing limited or chemically limited Mixing time scale in turbulent flows = DamkohlerNumber (Da) = If Da> 1 Fast chemistry and Da 1 Finite rate chemistry22 2016 Ansys , 2, 2016 Ansys Confidentia lModeling Examples: Fast ChemistryGas TurbineCO mass fractionFurnaceGasifier23 2016 Ansys , 2, 2016 Ansys Confidentia lModeling Examples: Slow ChemistryReentry packageVelocity (m/s)Re-entry capsuleFlame FlashbackReacting Rocket PlumeCVDH ydrogen auto-ignition24 2016 Ansys , 2, 2016 Ansys Confidentia lChallenges in Modeling Turbulent Reacting FlowsTurbulence Most industrial flows are turbulent.

8 DNS of non-reacting and reacting turbulent flows is not possible because of the wide range of time and length Realistic chemical mechanisms cannot be described by a single reaction equation. Tens of species, hundreds of reactions Known in detail for only a limited number of fuels Stiff kinetics (wide range of reacting time scales) Turbulence-Chemistry Interaction The sensitivity of reaction rates to local changes is complicated by enhanced mixing of turbulent before 2000 2000 to 2005 after 2005iso-ocatane (LLNL)iso-ocatane (ENSIC-CNRS)n-butane (LLNL)CH4 (Konnov)neo-pentane (LLNL)C2H4 (San Diego)CH4 (Leeds)Methyl Decanoate(LLNL)C16 (LLNL)C14 (LLNL)C12 (LLNL)C10 (LLNL)USC C1-C4 USC C2H4 PRFn-heptane (LLNL)skeletal iso-octane (Lu & Law)skeletal n-heptane (Lu & Law)1,3-ButadieneDME (Curran)C1-C3 (Qin et al) Number of reactionsNumber of 2005post-2005 Number of SpeciesNumber of ReactionsnC7H16C11H22O225 2016 Ansys , 2, 2016 Ansys Confidentia lFast Chemistry Models Eddy Dissipation model Premixed model Equilibrium model Steady Laminar Flamelet model Flamelet Generated Manifold model Partially premixed modelFinite Rate (Slow) Chemistry Models Laminar Finite rate model EDC Composition PDFS olid or Liquid Fuels(DPM) Droplet/particle dynamics DEM collisions Evaporation Devolatilization Heterogeneous reactionTransport Equations Mass Momentum Energy TurbulenceTurbulence Models RANS: k-e, k-w, LES, DES, Models NOx, Soot, SOxRadiation Models P1, DO (Gray/Non-gray)Real Gas Effects SRK, ARK, RK, PR, UDRGMC hemistry Solution Species OR Mixture fraction OR Progress variable OR.

9 Combusting Flow SolutionCombustion ModelsModels for Additional PhysicsOverview of Combustion Modeling26 2016 Ansys , 2, 2016 Ansys Confidentia lTurbulence Models RANS (K-epsilon, k-omega, SST, ) URANS URANS gives unphysical single mode unsteady behavior LES (Large Eddy Simulation) High resolution requirements in boundary layers DES (Detached Eddy Simulation) First industrial-strength model for high-Re with LES-content Increased complexity (grid sensitivity) due to explicit mix of two modelling concepts ELES (Embedded LES) Interface between RANS-LES: coarse mesh for the RANS and fine mesh for LES SAS (Scale-Adaptive Simulation) Provides LES mode in unsteady regions Avoid explicit mesh dependency Resolved length scale determined from solution Scale-adaptation based on von Karman length scale RANS/LES switch based on local L/LvKratioURANSSAS-URANS22//yUyULvK 27 2016 Ansys , 2, 2016 Ansys Confidentia lAir Hole OpeningTypes of FlamesDiffusion (or Non-Premixed) flames Separate streams for fuel and oxidizer Convection or diffusion of reactants from either side into a flame sheetPremixed flames Fuel and oxidizer are already mixed at the molecular level prior to ignition Diffusion heat and radicals from the products to the reactants Rate of propagation (flame speed)

10 Depends on the internal flame structurePartially Premixed flames Reacting systems with both non-premixed and premixed fuel/oxidizer streamsCloseOpenDiffusionPremixedDiffusi on flamePremixed flamePartially Premixed flameFuelOxidizerFuel + OxidizerFuel + OxidizerOxidizer OR Fuel28 2016 Ansys , 2, 2016 Ansys Confidentia lApproaches for Modeling Reacting Flows Simplify the chemistry Considers global chemical reaction mechanism Eddy Dissipation model (or Finite Rate/Eddy Dissipation) Decouple chemistry from flow (Fast Chemistry models Da>> 1) Use progress variable (C) approach Premixed model Use mixture fraction (Z) approach Non-Premixed model Use progress variable and mixture fraction approach Partially Premixed model Incorporate finite rate chemistry effects with laminar flameletsbased models Model detailed chemistry (Finite Rate Chemistry models Da~ 1 ) CPU intensive (large number of transport equations + stiff kinetics) Us