Turbulent Premixed Flames

Half-title......Page 3
Title......Page 5
Copyright......Page 6
Contents......Page 7
Preface......Page 11
Contributors......Page 13
1.1 Aims and Coverage......Page 19
1.2 Background......Page 21
1.3 Governing Equations......Page 24
1.3.1 Chemical Reaction Rate......Page 26
1.3.2 Mixture Fraction......Page 27
1.3.3 Spray Combustion......Page 28
1.4.2 RANS......Page 29
1.4.3 LES......Page 30
1.5 Equations of Turbulent Flow......Page 31
1.6 Combustion Regimes......Page 32
1.7 Modelling Strategies......Page 34
1.7.1 Turbulent Transport......Page 35
1.7.2 Reaction-Rate Closures......Page 38
1.7.3 Models for LES......Page 45
1.8 Data for Model Validation......Page 49
References......Page 51
2.1 Laminar Flamelets and the Bray, Moss, and Libby Model......Page 59
2.1.1 The BML Model......Page 60
2.1.2 Application to Stagnating Flows......Page 66
2.1.3 Gradient and Counter-Gradient Scalar Transport......Page 68
2.1.4 Laminar Flamelets......Page 70
2.1.5 A Simple Laminar Flamelet Model......Page 72
2.2 Flame Surface Density and the G Equation......Page 78
2.2.1 Flame Surface Density......Page 79
2.2.2 The G Equation for Laminar and Corrugated Turbulent Flames......Page 82
2.2.3 Detailed Chemistry Modelling with FSD......Page 86
2.2.4 FSD as a PDF Ingredient......Page 89
2.3 Scalar-Dissipation-Rate Approach......Page 92
2.3.1 Interlinks among SDR, FSD, and Mean Reaction Rate......Page 94
2.3.2 Transport Equation for the SDR......Page 95
2.3.3 A Situation of Reference – Non-Reactive Scalars......Page 96
2.3.4 SDR in Premixed Flames and Its Modelling......Page 99
2.3.5 Algebraic Models......Page 115
2.3.6 Predictions of Measurable Quantities......Page 118
2.3.7 LES Modelling for the SDR Approach......Page 119
2.4 Transported Probability Density Function Methods for Premixed Turbulent Flames......Page 120
2.4.1 Alternative PDF Transport Equations......Page 123
2.4.2 Closures for the Velocity Field......Page 125
2.4.3 Closures for the Scalar Dissipation Rate......Page 126
2.4.4 Reaction and Diffusion Terms......Page 127
2.4.5 Solution Methods......Page 128
2.4.6 Freely Propagating Premixed Turbulent Flames......Page 129
2.4.7 The Impact of Molecular-Mixing Terms......Page 131
2.4.8 Closure of Pressure Terms......Page 132
2.4.9 Premixed Flames at High Reynolds Numbers......Page 139
2.4.10 Partially Premixed Flames......Page 142
2.4.11 Scalar Transport at High Reynolds Numbers......Page 144
2.4.12 Conclusions......Page 148
Appendix 2.A......Page 150
Appendix 2.B......Page 151
Appendix 2.C......Page 152
References......Page 153
3.1 Instabilities in Flames......Page 169
3.1.1 Flame Instabilities......Page 170
3.1.2 Turbulent Burning, Extinctions, Relights, and Acoustic Waves......Page 184
3.1.3 Auto-Ignitive Burning......Page 186
3.2 Control Strategies for Combustion Instabilities......Page 191
3.2.1 Energy and Combustion Oscillations......Page 192
3.2.2 Passive Control......Page 194
3.2.3 Tuned Passive Control......Page 205
3.2.4 Active Control......Page 207
3.3.1 Basic Equations and Levels of Description......Page 220
3.3.2 LES of Compressible Reacting Flows......Page 224
3.3.3 3D Helmholtz Solver......Page 233
3.3.4 Upstream-Downstream Acoustic Conditions......Page 237
3.3.5 Application to an Annular Combustor......Page 239
References......Page 247
4.1 Application of Lean Flames in Internal Combustion Engines......Page 262
4.1.1 Legislation for Fuel Economy and for Emissions......Page 263
4.1.2 Lean-Burn Combustion Concepts for IC Engines......Page 274
4.1.3 Role of Experiments for Lean-Burn Combustion in IC Engines......Page 322
4.1.4 Concluding Remarks......Page 325
4.2 Application of Lean Flames in Aero Gas Turbines......Page 327
4.2.1 Background to the Design of Current Aero Gas Turbine Combustors......Page 330
4.2.2 Scoping the Low-Emissions Combustor Design Problem......Page 331
4.2.3 Emissions Requirements......Page 332
4.2.4 Engine Design Trend and Effect of Engine Cycle on Emissions......Page 335
4.2.5 History of Emissions Research to A.D. 2000......Page 336
4.2.6 Operability......Page 339
4.2.7 Performance Compromise after Concept Demonstration......Page 341
4.2.8 Lean-Burn Options......Page 342
4.2.9 Conclusions......Page 349
4.3 Application of Lean Flames in Stationary Gas Turbines......Page 353
4.3.1 Common Combustor Configurations......Page 354
4.3.2 Fuels......Page 356
4.3.3 Water Injection......Page 357
4.3.4 Emissions Regulations......Page 358
4.3.5 Available NOx Control Technologies......Page 360
4.3.7 Combustion Instability......Page 363
4.3.9 Auto-Ignition......Page 366
4.3.11 Combustion Research for Industrial Gas Turbines......Page 367
4.3.12 Future Trends and Research Emphasis......Page 368
References......Page 369
5.1 Utilization of Hot Burnt Gas for Better Control of Combustion and Emissions......Page 383
5.1.1 Axially Staged Lean-Mixture Injection......Page 385
5.1.2 Application of the Concept to Gas Turbine Combustors......Page 392
5.1.3 Numerical Simulation towards Design Optimization......Page 393
5.2.1 LPP Combustors......Page 396
5.2.2 Reliable Models that Can Predict Lift-Off and Blowout Limits of Flames in Co-Flows or Cross-Flows......Page 401
5.2.3 New Technology in Measurement Techniques......Page 404
5.2.4 Unresolved Fundamental Issues......Page 408
5.2.5 Summary......Page 413
5.3.1 Modelling Requirements......Page 414
5.3.2 Assessment of Models......Page 416
5.3.3 Future Directions......Page 418
References......Page 419
Nomenclature......Page 425
Greek Symbols......Page 429
Acronyms......Page 431
Index......Page 433
Color Plates......Page 441