采用多物理场多学科耦合方法对内燃机进行设计优化register.ansys.com.cn/ansyschina/20151117aswc/采用多...optimize a combustion system to meet performance (power,

采用多物理场-多学科耦合方法对内燃机进行设计优化

Outline• Why Multiphysics/Multidisciplinary?• Concurrent Engineering: The Basics• Parameterization and Optimization Scenarios• Conjugate Heat Transfer Work Flows• Co-Simulation: 1D/3D Coupling• Thermal Stress and Fatigue Considerations• Future Outlook

Friday, November 20, 2015 2015 Automotive Simulation World Congress 2

Why Multiphysics/Multidisciplinary?


Piston Over Heating

Head Gasket Failure

Cylinder Head Cracking

Cylinder Liner Wear

Engine Simulation Personas• Combustion Analyst

• Performs analysis on in-cylinder engines (ICE) focusing on charge motion/preparation, spray, combustion and emissions. Role is to optimize a combustion system to meet performance (power, torque etc.), fuel economy and emissions for a target market.

• CHT Analyst• Performs analysis on powertrain components, sub-systems and

systems focusing on cooling and lubrication. Typically use information from combustion CFD as input. Role is to optimize heat transfer in the cooling/lubrication system to meet solid metal temperature limits/targets.


Engine Simulation Personas• FEA Analyst

• Performs analysis on powertrain components and sub-systems (less focus on complete systems) focusing on thermal-stress analysis and fatigue. Typically use information from combustion/CHT fluids analysis as input. Role is to optimize the structural components of the engine to meet durability targets by focusing on metal temperature limits, high stress locations and the probability of cracking.

• Fatigue Analyst• Performs life prediction on powertrain components. Typically use

information from stress analysis as input. Role is to identify factors that will impact or potentially lead to product failure (component size, load conditions, surface finishes/treatments) and recommend corrective design changes.


Concurrent Engineering: The Basics

• Project tasks fall into three categories• Dependent (Series)• Independent (Parallel)• Interdependent (Coupled)

• Large projects decomposed into smaller projects and many functional teams

• Projects (and people) can be geographically distributed

• Challenge: How to integrate everything together into a system solution?

Friday, November 20, 2015 2015 Automotive Simulation World Congress 6Project Task Sequences

MUST Design And Optimize For Durability


Combustion CFD

Thermal/Stress Fatigue

Conjugate Heat Transfer (CHT)

Conceptual Design Via Parameterization and Optimization

• Parametric CAD Model• Bi-directional

connectivity with Workbench to enable CAD to solution process

• Automated and persistent work flows

• Easily extended to design exploration/optimization

• Non-Parametric CAD Model

• Topology Optimization via mesh morphing (Fluent, RBF-Morph) and/or adjoint methods


Mesh MorphingControl Volume

Adjoint ShapeSensitivity Contours

Streamlined Pre-Processing• Easy geometry preparation with Space

Claim or Design Modeler• Full Engine, Sector, Symmetry, De-Featuring

etc.• Access to ANSYS pre-processing

technologies

• CAD connectivity with full modeling and parametric capabilities

• Extendable to design points (i.e. parametric studies), DOE and optimization

• Forte supports Fluent mesh file format• Mesh file can be either surface or volume

mesh and named zones in imported mesh file preserved


Example: Parametric Piston Bowl• Geometrical parameters

• Bowl radius, bowl depth, throat radius, lip radius, lip angle etc.

• Forte CFD inputs• All numerical values, booleans,

tables and profiles can be used for parametric studies

• Forte CFD outputs• All performance outputs standard

(PCP, burn angles/durations, GISFC, IMEP, NOx, Soot etc.)

• Not yet an integrated process in Workbench but scriptable

Friday, November 20, 2015 2015 Automotive Simulation World Congress 10ANSYS Workbench/Forte Parametric Studies

Cleanup geometry using DM or Space Claim

Create volume defining fluid domain

WB-ICE automatically decomposes to required boundary surfaces

WB-ICE Generates a water-tight surface meshForte automatically

generates the moving volume mesh on-the-fly, during the simulation

In R17, Forte Integrated into WB-ICE

Includesautomatic reporting through WB-ICE

In R17, CFD-Post Visualization of Forte Results

CHT For Combustion System Design


• Variety of cross-physics and data exchange approaches used– Use of empirical heat data in a

zonal combustion face map– Measured or predicted heat

release profile imposed as energy source in gas exchange CFD model

– Iterative combustion to non-combustion approach

• Challenges include– Different user-personas (Designer,

CFD/FEM analyst), multiple simulation tools (1D/2D/3D), multiple functional groups (CFD, FEA, System)

Courtesy: Mercury Marine

Cylinder Head Temperature Predictions Courtesy: Cummins

Co-Simulation: 1D/3D Coupling• Typical Coupling Applications

• Intake/Exhaust Manifolds, AIS, Filters, Mufflers, EGR/PCV, Catalysts, Cylinders

• Dynamic Coupling with 1D Simulation Tools

• GT-Suite, WAVE, Virtual Engines for engine simulation

• Solution Benefits• Capture of complete system level

interactions, accurate CFD boundary conditions etc.

• Insights into cylinder-to-cylinder performance, variations etc.

• One coupled engine cycle with ~1M CFD cells < 3h on 64 CPU’s (large model)


Diesel Intake ManifoldCourtesy Cummins

Motorsports: Intake Manifold & Exhaust Cross-Pipe

Thermal Stress Best Practice [1]• Example: Six Cylinder Engine

Assembly (~150 parts, ~900 bodies,~5M nodes, 400+ contact pairs, 70+ named selections, 40+ bolt pre-tensions)

• Geometry preparation and cleanup• De-featuring entities, slicing and

instancing liners, valves, bolts• Part management

• Tags to manage selections/views, tree-view filtering

• Automatic contact creation with specific tolerance value


Engine Assembly Cross-Section

Part Management, Tags and Filters

Thermal Stress Best Practice [2]• Local meshing for valves, gaskets,

bolts and combustion face refinements; global mesh elsewhere

• Define pre-tension for one bolt using Object Generator, then use NS/TAGS to populate for all bolts; copy/paste load data

• Map via External Data (or apply) pressure/thermal loads and injector forces

• Use gasket modeling best practice• Complete setup and solve for a Static

Structural analysis in <12 hours


Bolt & Insert Meshing

Object Generator

Stress Distribution

Steady State vs. TransientLoading and Fatigue

• Steady state loads do not always produce the highest stresses• Cyclic stresses can cause failure at loads lower than material tensile/yield

strength• Transient loading behavior critical for fatigue/life predictions

ANSYS Customization Suite• Two-Tier Customization Suite

• SDK: Workflow and data integration of 3rd

party software• ACT: Custom interfaces for WB/Mechanical

and beyond

• SDK already used by partners such as nCode, fe-safe and many others

• ACT has been used to customize interfaces and build vertical applications


Integration Outlook …

External Tools, In-House Tools etc.

Summary• Some key take ways from this multiphysics and

multidisciplinary solution paradigm• Engine design is much more than developing a combustion

system• Depth and diversity within all physics and at all stages of a design

process is necessary (combustion, fluid, thermal, stress, durability, fatigue)

• Tools and processes that cater to different user personas and disciplines within a design process is important (Designer, Analyst, Systems)

• A collaborative and common platform for integrated CAE is a requirement given product design demands (engine calibration, packaging, controls development, system optimization etc.)

• ANSYS is committed to the continuous advancement of its integrated solution work flows and processes


谢谢

Documents

采用多物理场 多学科耦合方法 对内燃机进行设计优化register.ansys.com.cn/ansyschina/20151117aswc/采用多...optimize a combustion system to meet performance (power,

采用多物理场多学科耦合方法对内燃机进行设计优化register.ansys.com.cn/ansyschina/20151117aswc/采用多...optimize a combustion system to meet performance (power,