Chiodi An Innovative 3D-CFD-Approach towards Virtual Development of Internal Combustion Engines

2011
ISBN: 978-3-8348-8131-1
Verlag: Vieweg & Teubner
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 245 Seiten, eBook

Marco Chiodi obtained his Ph.D. by Prof. Dr.-Ing. Michael Bargende at the University of Stuttgart.

Zielgruppe

Research

Autoren/Hrsg.

Chiodi, Marco

Inhaltsverzeichnis

1;Acknowledgments;7
2;Table of Contents;8
3;Abstract;14
4;Zusammenfassung;18
5;Symbols, Subscripts and Abbreviations;22
5.1;Roman Symbols;22
5.2;Greek Symbols;29
5.3;Subscripts and Abbreviations;30
6;1 Introduction;33
6.1;1.1 Society and Transportation;33
6.2;1.2 The Fascination of Internal Combustion Engines;33
6.3;1.3 Internal Combustion Engines and Sustainable Transportation;34
6.3.1;1.3.1 Development Targets of Internal Combustion Engines in the Past;34
6.3.2;1.3.2 The Role of Alternative Engine Concepts;36
6.3.3;1.3.3 Development Targets of Internal Combustion Engines in the Future;36
6.3.3.1;1.3.3.1 General Improvement of actual Solutions;37
6.3.3.2;1.3.3.2 Downsizing and Turbo-Charging;37
6.3.3.3;1.3.3.3 Hybridization;37
6.3.3.4;1.3.3.4 Development of Innovative Combustion Solutions;38
6.3.3.5;1.3.3.5 Alternative Fuels;38
6.4;1.4 How to Face the Complexity of Future Internal- Combustion-Engines;40
7;2 Simulation of Internal Combustion Engines;42
7.1;2.1 Simulation towards Virtual Engine Development;43
7.1.1;2.1.1 One Tool for the Simulation of the Entire Engine?;43
7.1.1.1;2.1.1.1 Mechanical Numerical Analysis;44
7.1.1.2;2.1.1.2 Engine Operating Cycle Analyses;45
7.1.2;2.1.2 The Future Challenge: an improved Integration of Simulation Tools;47
7.2;2.2 Today’s Repartition of the Resources in Engine Development;49
7.3;2.3 Introduction to Engine Processes Modeling in the Simulation of the Operating Cycle;53
8;3 Engine Energy- Balance;57
8.1;3.1 Energy-Balance of the Combustion Chamber;57
8.2;3.2 Energy-Balance of the Entire Engine;58
8.3;3.3 The Role of Engine Energy-Balance in the Engine Development Process;60
9;4 Real Working-Process Analysis;61
9.1;4.1 Introduction;61
9.2;4.2 Fundamental Equations;63
9.3;4.3 Thermal State Equation of the Working Fluid;64
9.4;4.4 Engine Modeling (Engine-Specific Models);64
9.4.1;4.4.1 Modeling of the Thermo-Physical Properties of the Working Fluid;65
9.4.2;4.4.2 Modeling of the Wall Heat-Transfer;66
9.4.3;4.4.3 Modeling of the Combustion Process;66
9.4.3.1;4.4.3.1 Empirical Models;67
9.4.3.2;4.4.3.2 Quasi-dimensional Models;72
9.5;4.5 Two Approaches in the Calculation of the Real Working-Process;75
9.5.1;4.5.1 Pressure Profile Calculation - Combustion Profile Supply;76
9.5.2;4.5.2 Combustion Profile Calculation - Pressure Profile Supply;76
9.6;4.6 The Role of Real Working-Process Analysis in the Engine Development Process;77
10;5 One-Dimensional Simulation (1D-CFD-Simulation);80
10.1;5.1 Introduction;80
10.2;5.2 Engine Layout and Conservation Equations;81
10.3;5.3 The Role of the 1D-CFD-Simulation in the Engine Development Process;82
11;6 Three-Dimensional Simulation (3D-CFD Simulation);84
11.1;6.1 Fundamental Equations;85
11.1.1;6.1.1 Mass Conservation Equation;85
11.1.2;6.1.2 Species Mass Conservation Equation;86
11.1.3;6.1.3 Momentum Conservation Equation (Navier-Stokes’ Equation);86
11.1.4;6.1.4 Energy Conservation Equation;87
11.2;6.2 Engine Modeling;87
11.2.1;6.2.1 Universally-Valid 3D-CFD-Models;88
11.2.1.1;6.2.1.1 Modeling of the Thermo-physical Properties of the Working Fluid;88
11.2.1.2;6.2.1.2 Modeling of Non-Convective Processes;89
11.2.1.3;6.2.1.3 Turbulence Modeling;91
11.2.1.4;6.2.1.4 Combustion Models;98
11.2.1.5;6.2.1.5 Wall Heat-Transfer Models;99
11.2.2;6.2.2 Introduction to Engine-Specific 3D-CFD-Models;99
11.3;6.3 Discretization Practices (Numerical Implementation);100
11.3.1;6.3.1 Spatial Flux Discretization;102
11.3.1.1;6.3.1.1 Low-Order Differencing Scheme – Upwind Differencing (UD);102
11.3.1.2;6.3.1.2 Higher-Order Differencing Scheme;103
11.4;6.4 The Role of the 3D-CFD-Simulation in the Engine Development Process;103
12;7 Towards an improved 3D-CFD- Simulation;105
12.1;7.1 An innovative Fast-Response 3D-CFD-Tool: QuickSim;105
12.1.1;7.1.1 Fast Analysis;106
12.1.1.1;7.1.1.1 Mesh Discretization for DNS Simulations;108
12.1.1.2;7.1.1.2 Mesh Discretization for LES Simulations;108
12.1.1.3;7.1.1.3 Mesh Discretization for QuickSim Simulations;109
12.1.2;7.1.2 Reliable Calculation;110
12.1.3;7.1.3 User-Friendliness;111
12.1.4;7.1.4 Clear Representation of the Results;112
12.1.5;7.1.5 Cost Efficiency;113
12.1.5.1;7.1.5.1 Processor Utilization for QuickSim Simulations;113
12.2;7.2 Additional Features of QuickSim;114
12.2.1;7.2.1 Simulation of several successive Engine Operating Cycles;114
12.2.2;7.2.2 Extension of the 3D-CFD-Domain up to a Full-Engine Simulation;116
12.2.3;7.2.3 The Simulation of a Flow Test-Bench;119
12.3;7.3 Summary of the QuickSim Features;121
12.4;7.4 QuickSim’s Calculation Layout;122
13;8 3D-CFD-Modeling of the Thermodynamic Properties of the Working Fluid;126
13.1;8.1 Introduction;126
13.2;8.2 Chemical Composition of the Working Fluid Mixture;127
13.2.1;8.2.1 One-Step Fuel-Oxidation Reaction Mechanism;127
13.2.2;8.2.2 The Reality: More than Thousand Intermediate Products;129
13.3;8.3 Traditional Approach;131
13.4;8.4 QuickSim’s Approach: Few Species for the Description of the Working Fluid;132
13.4.1;8.4.1 QuickSim’s Approach: A universally-valid Chemical Reaction Scheme for the Description of Burned Gas;137
13.4.1.1;8.4.1.1 Chemical Equilibrium Assumption;139
13.4.1.2;8.4.1.2 The proposed Chemical Reaction Scheme;140
13.4.1.3;8.4.1.3 A “frozen” Composition at low Temperatures;142
13.4.1.4;8.4.1.4 Results: The Chemical Composition of Burned Gas;143
13.4.2;8.4.2 QuickSim’s Approach: Conclusive Modeling of the Thermodynamic Properties of Burned Gas;146
13.4.2.1;8.4.2.1 Heat Release at the Flame Front and Post-Oxidation of Exhaust Gas with Fresh Gas;148
13.4.2.2;8.4.2.2 Heat Exchange due to Dissociation Effects and Post-Oxidation within Exhaust Gas;150
13.4.2.3;8.4.2.3 Combustion Conversion Efficiency;153
14;9 3D-CFD-Modeling of the Combustion for SI-Engines;155
14.1;9.1 Introduction;155
14.2;9.2 Flame Propagation Modeling (Weller Model);158
14.3;9.3 QuickSim’s Approach: Implementation Improvement;160
14.3.1;9.3.1 Numerical Implementation of the Flame Propagation Model;160
14.3.2;9.3.2 Numerical Inconsistencies at the Flame Front;163
14.3.2.1;9.3.2.1 Expedients for the Numerical Inconsistencies at the Flame Front;165
14.3.3;9.3.3 Local Two-Zones Model;166
14.3.4;9.3.4 Ignition Model;171
14.3.5;9.3.5 Final Implementation Procedure;173
14.4;9.4 Results;175
15;10 3D-CFD-Modeling of the Wall Heat-Transfer;177
15.1;10.1 Introduction;177
15.1.1;10.1.1 Phenomena Understanding, Calculation Approach and Considerations;178
15.2;10.2 State-of the-Art of Engine Heat-Transfer Calculationin the 3D-CFD-Simualtion;180
15.2.1;10.2.1 The Wall Function Approach;180
15.2.2;10.2.2 Low Reynolds Number Models;182
15.2.3;10.2.3 Phenomenological Heat-Transfer Models in the Real Working-Process Analysis (WP);183
15.2.3.1;10.2.3.1 Motivation for a Phenomenological Approach;184
15.2.3.2;10.2.3.2 Woschni’s Correlation;184
15.2.3.3;10.2.3.3 Hohenberg’s Correlation;185
15.2.3.4;10.2.3.4 Bargende’s Correlation;185
15.2.4;10.2.4 Comparison between the 3D-CFD-Heat-Transfer (Wall- Function Model) and the Real Working-Process Analysis;187
15.2.4.1;10.2.4.1 Sensitivity Analysis of the 3D-CFD-Heat-Transfer calculated with a Wall-Function Model;190
15.2.5;10.2.5 QuickSim’s Approach: A new Phenomenological Heat- Transfer Model in the 3D-CFD-Simulation;194
15.2.5.1;10.2.5.1 The Heat-Transfer during the Working Cycle;195
15.2.5.2;10.2.5.2 The Heat-Transfer during the Charge Changing Period;201
15.3;10.3 Results;201
15.4;10.4 Influence of 3D-CFD-Heat-Transfer-Models on the Engine Energy-Balance;203
16;11 A Way towards Virtual Engine Development;206
16.1;11.1 Introduction;206
16.2;11.2 The Hardware: a turbocharged CNG Race-Engine;206
16.3;11.3 Setting of the 3D-CFD-Simulation;208
16.3.1;11.3.1 Initial Conditions and Properties of the Working Fluid;210
16.3.2;11.3.2 Boundary Conditions;211
16.4;11.4 CNG-Injector Model;213
16.4.1;11.4.1 Traditional Gas Injection Modeling;215
16.4.2;11.4.2 Gas Injection Modeling in QuickSim;216
16.5;11.5 3D-CFD-Domains limited to the Cylinder;218
16.5.1;11.5.1 3D-CFD-Simulation excluding the Fuel Injectors;218
16.5.2;11.5.2 3D-CFD-Simulation including the Fuel Injectors;221
16.6;11.6 Extension of the 3D-CFD-Domain: One Cylinder with the Airbox;226
16.6.1;11.6.1 Between Predictability and Results Consistency;227
16.6.1.1;11.6.1.1 QuickSim’s Improved Approach: The integrated 0D- and1D-CFD Simulationof the missing Cylinders;228
16.7;11.7 3D-CFD-Simulation of the Full Engine;231
16.7.1;11.7.1 Results and 3D-CFD-Flow Field Investigations on the Full Engine;232
16.7.1.1;11.7.1.1 Mixture Formation;234
16.7.1.2;11.7.1.2 Residual Gas Distribution;239
16.7.1.3;11.7.1.3 Turbulence;241
16.7.1.4;11.7.1.4 Combustion;243
16.7.1.5;11.7.1.5 Convergence of the Results;245
16.7.2;11.7.2 Result Comparison among different Operating Conditions;245
16.8;11.8 The Simulation of successive Operating Cycles;247
16.9;11.9 Result Comparison among the different Extensions of the 3D-CFD-Domain;250
17;12 Conclusion;252
18;13 Outlook;254
19;Appendix A;256
19.1;A.1 Vector and Matrix Analysis;256
20;Appendix B;258
20.1;B.1 Thermodynamic Properties of the Working Fluid;258
21;References;269

Über Autor(innen)

Marco Chiodi obtained his Ph.D. by Prof. Dr.-Ing. Michael Bargende at the University of Stuttgart.