cax in automotive and engine technology - ivt.tugraz.at · • multi-body systems ... - assy...

CAx in Automotive and Engine Technology

Assoc.Prof. Dr. Roland Kirchberger17th and 24th October 2016

Winter Term 2016/17

CAx in Automotive and Engine Technology 2

Fundamentals of CAx in Engine Design – Examples and Status

Very early history of CAx Geometry Process Engine Mechanics Functionality Development Engine Management and Calibration

Selected Examples of CAx in Engine Engineering

Content


About 200 years ago (1809) Ferdinand Redtenbacher, an Austrian engineer started with the „Science of mechanical engineering“ (Steyr, Upper Austria)Later, Carl Benz and Eugen Langen (friend of Nikolaus Otto), started with the optimization of steam engines, to improve the efficiency and the material usage.

Prototype = Series

Hence very high quality of design was mandatory

Stress analysis and thermodynamic analysis were of biggest concern in the beginning

Historic Motivation for Simulation – Large Engines


• 2D/3D Design Data• Type Range Family• Process Data• Engine DMU• Visualisation• Process Data

Management• Geometry Data

Management

Vehicle

Production

Engine

Type Range

Geometry Process


Valve Train

Belt Drive / Tensioner

Coolant Flow in Cyl. Head and Block

Engine Mountings

Heat Transfer andThermal Stresses

Piston and Cranktrain

Turbocharger

Exhaust System

Chain Drive

VibrationCrank Shaft / Damper

Crank Shaft, Bearings

VibrationAcoustics

Friction

CAx Application in the Development of Engine Mechanics


• Statics• Dynamics• Multi-body Systems• Thermo-mechanics• Fatigue• Acoustics, NVH• Process Simulation• Topology

Optimization

Source: Dr. Nefischer, Handbuch Verbrennungsmotorlow

high

Degree Crankangle [°CA]

Ben

ding

Mom

ent

Engine - Mechanics


Acoustics

Statics

Thermo-mechanics

Fatigue

Process Simulation

Multi-body systems

Dynamics

Topology optimization

StatusGoal

CAx Engine – Mechanics


Equivalent system single valve

valve spring

valve plate

valve shaft

tappet

cam

connecting geometry

radial bushing

shaftshaft with belt pulley

rotational excitation

belt pulley

TYCON – VALVE TRAIN

Example for Problem Orientated MBS


Valve Seat Force – Inlet Cam

Pressure Cam / Tappet

Acceleration of Inlet Valve

TYCON – Valve Train


Simplification of the 3D Model

Pressure distribution in the cylinder head gasket

Example for Application of a Static FEM


Mould Filling History after 6,8,10,12,14,16,18,20 sec

Example for Process Optimization for Aluminum Sand Casting


Local liquid fractionafter 87 sec

values<30% invisible

Local densityafter solidification

values>98% invisible

Temperature distributionafter 88 sec

Example for Process Optimization for Aluminum Sand Casting


Example for Acoustic Optimization of an Engine Crankcase


New light weight crankcase and capsule, to reduce the typical bell motion

Example for Acoustic Optimization of an Engine Crankcase


Gas Exchange

Calibration Parameter

Mixture Formation

Injection Hydraulics

Combustion

Emission Formation

Turbocharger

Catalytic Converter Behavior

Electr. System /Charging

LabCar / HIL

Oil System

EGR Distribution,Dynamics

Unfiltered / Filtered Air

CAx Application in Functionality Development of Engines


...

Heat flux/Ion-current sensors

Standard measurement

...

Combustion

Gas exchange

...

LDA

LIF

...

Combustion/Emissions

Mixture formation

Closed loopAnalysis/Synthesis

Engine conceptspecifications

Powertrain targets

1-cylinder engine

3D-Simulation

Optimized engineconcept

0D+1D-Simulation

optical engine

Combustion Development Process


Test BenchSingle Cylinder

Research Engine

p, TV p, TU

0D- Simulation

3D-CFD Simulation3D-CFD SimulationTest Bench Full Engine

HONNOH 22 HONNOH 22

OONNO 222 OONNO 222

NONOOON 2 NONOOON 2

HNONOH HNONOH ONONO 2 ONONO 2

NNOON 2 NNOON 2

Emission Formation Sim.

1D- Simulation

Process Functionality Development Engine


Status CFD-Simulation: Reproduction of fundamental mechanisms

inlet flow, charge motion,fuel injection, evaporation, combustion

Understanding of mixture formation and combustion Time intensive Direct numerical simulation not yet possible

Target CFD – Simulation (not entirely achieved yet):Prediction of Behavior

Increase of quality of predictionSelection of test configurationsSensitivity to small changes

Injection process, fuel – wall interaction Combustion, knocking, emission Formation, …

Mixture Formation and Combustion of DI Engines

CAx in Automotive and Engine Technology Source: Kemmler, Daimler Chrysler

Air-Fuel RatioMain Injection

Ingnition TimingVar. Length Inlet Pipe

Inlet Valve TimingOutlet Valve Timing

Charge Motion Device

Coolant Thermostat

Rail PressurePilot Injection

T1-Time

Delta Ignition TimingT2-Time

Post Injection

Total Injected MassNumber of Injections

External EGRBoost Pressure

Outlet Valve Lift

Inlet Valve Lift

Port Injection Direct Injection

Application Effort

Number of Variables

R4: Inline 4Cyl. V6: V-Engine ATL: Turbocharged

Otto Engine Concepts and Degrees of Freedom

CAx in Automotive and Engine Technology

Injection Timing early

Igni

tion

Tim

ing

e

arly

BSFCmin

Optimization of Operating Parameters at Stratified Part Load Operation

Parameter: Verification/Application

Ignition Timing 5

Start of Injection 4

Injection Pressure 4

Intake Manifold Pressure 4

EGR 4

Swirl 4

per Operating Point >5000 Meas. Pts.

Automated Test Bench Operation

with Interface Engine Management – Test Bench

Choice of Criteria (HC, COV, BSFC)

Automated Optimization following Main Criteria

Statistic Experiment Planning and Similar Prod.


Design of Experiments (DoE) for ApplicationThe key word DoE mostly refers to the following two topics:

Statistic Experiment Planning Original meaning of DoE Common speech: selective choice of measurement points from a

statistic point of view Target: maximum of information with acceptable accuracy about a

complex system with a minimum of measurement points.

Modelling of the system under consideration Equation systems (Cornerstone, RS1, Matlab/KFR) Neural networks (Nemo) Modeling of measurement errors Assessment of the modeling quality Verification by measurement of found optima


Fullpass

I / O-board

Bypass

ECU

Lab CarHiLHiL::- Ascet- Dspace

Validation-,Analysis-Test Beds/-ToolsFired SingleCylinder, Optical Engine, Flow Rigs/ Combustion Analysis

Conception

Digital Mock-UpCAD:CAD:-Def .-Spec .-Design

Engi

neH

ardw

are

ApplicationCAM:CAM:- Casting model- Machining

CAE:CAE:- Assy sim.- FEM- Dynamics- VR- CFD, Gas Exchange

Analysis/Simulation

RapidRapidPrototypingPrototyping

VirtualVirtualPrototypingPrototyping

CASE:CASE:- Idea, Definition- Spec., Modelling

Engi

neFu

nctio

ns

Virtual Engine

Engine/Gear BoxModel

(VehicleModel)Con

trolle

r

Function Mock-Up

SiLSiL::- ATMOS, Promo,...- Matlab/Simulink, ...

Virtual Engine

Engine/Gear BoxModel

(VehicleModel)

Con

trolle

r

Function Simulation

Analogy Engine Hardware – ECU-Functionality Development


mzu mabp,V,T

+

Empirical Models (e.g. engine maps)+ simple form of modeling- exponential increase of application effort

Modeling of the Physics of the Processes+ analytical description of the process

dependable and accurate- complex modeling (expert know-how is

required)

Problem: High effort for complex processes !!!

Engine Management and Functionality Development


Virtual Engine remains (in the foreseeable future)a vision !

Geometry Process: CAx is common practice in development process

Engine Mechanics: CAx is standard and applied extensively, up to very complex and coupled models of stat./dyn., thermo-mechanical and acoustic processes.

Functionality Development: Modeling of combustion process and engine concepts with various 0-, 1- and 3-D procedures; Need for further development especially in field of combustion and emissions formation

Engine Management and Calibration: CAx gives the base for indispensable support for systems with numerous degrees of freedom (e.g. DI Otto, CR-Diesel) and for the development and test bench operation

Fundamentals of CAx in Engine Development - Summary


Development Phase

Com

plex

ity

Concept Phase Design Phase Prototype Phase

Empirical Know How & Simulations

Complex Simulations (3D CFD, FEM)

Test Bench, part / complete system simulations

Schematic of the Development Process for an Engine


Concept Phase Gas Exchange Simulation, Supercharging, Injection System, Combustion Process Simulation for efficiency-, WOT-, emission- assessment

of a concept, Software in the Loop, Thermal Management, Mechanics,...

Design Phase Design, Optics Engine Mechanics Dynamics, NVH

Prototype Phase, Test Bench Rapid Prototyping Simulation of System „Combustion Chamber“, Combustion Diagnostics (TCA,..) Engine Management, Application Complete System Analysis, HIL

Selected Examples


Simulation Methods: Fill- and Drain Method

Influence of gas dynamics (e.g. pressure pulse of ram effect or tuned intake pressure charging) cannot be incorporatedExample: Layout calculation of turbo charger

1D Gas Dynamics Standard application for layout of gas exchange system, commercially available software (Boost, Promo, Wave,..)

3D Gas DynamicsTo some extend applied for assessment of losses, for local „peculiarities“ as extension of the 1D simulation

Simulation of the Gas Exchange


Potential concerning efficiency

8 10 12 14 16 18 20Compression ratio [-]

30

32

34

36

38

40

42

44

50

Indi

cate

d ef

ficie

ncy i

HP

[%] 46

48

n=2.000 RPMIMEP=6 bar

Wall heatlosses

- 10%

+ 25%

- 35%

+ 10%

- 25%

CurrentConfig.


Abb 5.2 , Boost

Simulation of Gas Exchange Process


Source: Dr.Nefischer, BMW

low

highEGR concentration in lower chamber

EGR concentration in upper chamber

Optimizationbefore

after

Optimization of EGR - Distributionin the Intake Manifold


Status Simulation: The working process of the ICE is too complex (up to now) to

be simulated in its entirety. (including the thermodynamic-, chemical-, flow dynamic processes in the comb. chamber, intake & exhaust System, turbo charging, EGR,..)

Very close combination with analysis of existing systems Various simplifications necessary to limit effort of modeling

and CPU time Goal Simulation: Prediction of behavior of new or altered systems Layout of new engine concepts, selection of models for

testing, reduction of number of expensive prototypes ...

Literature: Thermodynamik der VKM (Pischinger, Klell, Sams) , Springer-Verlag

Simulation of the System „Combustion Chamber“


Phenomenological Models: Phenomena are described with empirical or half empirical

functions of the relevant parameters, without direct math. incorporation of the physics laws of conservation

In general simple in set up and handling, in most cases each application requires

coefficients only available from experimentsExample: model of wall heat transfer in combustion

chamberPhysical Models: Based on mathematical formulations of fundamental laws of

physics (Conservation of mass, energy, momentum, …) Statistic models

Implemented Calculation Models for the Simulation of the System „Combustion Chamber“


For the description of the transient system „Combustion Chamber“ time and 3 positional coordinates have to be considered. (Required) simplifications: 0D Models (better: „time-dimensional“)

Consideration of time- but not position dependent parameters

Quasidimensional Approaches Consideration of local phenomena and geometrical characteristics within a 0D-model, applied in e.g. flow simulation, combustion, heat transfer

One- and multi dimensional ApproachesOne dimensional models are often used for the analysis of flow behavior of intake and exhaust systems

More complex flow fields require multi dimensional models (CFD – Computational Fluid Dynamics)

Implemented Calculation Models for the Simulation of the System „Combustion Chamber“


Three Dimensional ModelingProcesses in the ICE have Reynolds Numbers in the range of 105 to 107; Direct Numerical Simulation (DNS) is up to now impossible (complete description of position and time dependent flow field today possible up to order of magnitude Re < 103 )

Coarse Structure Simulation (Large Eddy Simulation LES)Selective simulation of important areas of a flow field or turbulence spectrum - mesh is adapted to turbulence structures

Statistical ApproachSplitting of the flow parameters into mean value and variation, use of turbulence models (e.g. kε model)

Multi Dimensional Approaches for the Simulation of the System „Combustion Chamber“


Examples of CFD SimulationPremixed Combustion in Large EnginesUse of CFD Simulation for the analysis of the flame propagation depending on different combustion types and for the optimization of geometry parameters

Structure with approximately 150.000 cellsCombustion and flame calculated with PDF-approach

(probability density function) Analysis of swirl effect


VerificationVerification

Flow, Mixture Formation

Application:

Combustion

Knocking

Model Development

347 °KW 352 °KW 357 °KW 362 °KW 367 °KW 372 °KW

347 °KW 352 °KW 357 °KW 362 °KW 367 °KW 372 °KW

Without swirl:

With swirl:

Influence of Swirl Motion on Combustion

cax in automotive and engine technology - ivt.tugraz.at · • multi-body systems ... - assy...

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