Principles of Combustion

KENNETH K. KUO, PHD, is Distinguished Professor of Mechanical Engineering and Director of the High Pressure Combustion Laboratory in the College of Engineering at The Pennsylvania State University. He established the combustion laboratory at Penn State and is recognized as one of the leading researchers in propulsion-related combustion.

Preface xxi

Preface to the First Edition xxv

Introduction 1

Importance of Combustion in Various Applications 1

Related Constituent Disciplines for Combustion Studies 3

General Method of Approach to Combustion Problems 4

General Objectives of Combustion Modeling 4

Classification of Combustion Problems 4

General Structure of a Theoretical Model 6

Governing Equations for Combustion Modeling (Conservation and Transport Equations) 6

Some Common Assumptions Made in Combustion Models (Especially for Classical Models) 6

Several Basic Definitions 8

1 Review of Chemical Thermodynamics 11

Nomenclature 11

1 Brief Statement of Thermodynamic Laws 15

2 Equation of State 17

3 Conservation of Mass 18

4 The First Law of Thermodynamics; Conservation of Energy 20

5 The Second Law of Thermodynamics 24

6 Criteria for Equilibrium 34

7 Conservation of Atomic Species 36

8 Various Methods for Reactant-Fraction Specification 38

9 Standard Enthalpies of Formation 43

10 Thermochemical Laws 47

11 Relationship Between Bond Energies and Heats of Formation 48

12 Heats of Reaction for Constant-Pressure

13 Energy Balance Considerations for Flame Temperature

14 Equilibrium Constants 73

15 Real-Gas Equations of State and Fugacity Calculation 90

16 More-Complicated Dissociation in the Combustion of Hydrocarbons 93

17 The Clausius–Clapeyron Equation for Phase Equilibrium 96

18 Calculation of Equilibrium Compositions with NASA’s CEA Computer Program 98

19 Other Well-Established Chemical Equilibrium Codes 107

References 109

Homework 110

Projects 114

2 Chemical Kinetics and Reaction Mechanisms 116 Nomenclature 116

1 Rates of Reaction and Their Functional Dependence 118

2 One-Step Chemical Reactions of Various Orders 141

3 Consecutive Reactions 148

4 Competitive Reactions 150

5 Opposing Reactions 150

6 Chain Reactions 154

7 Chain-Branching Explosions 162

8 Chemkin Analysis and Code Application

9 Surface Reactions 173

10 Rate Laws for Isothermal Reactions Utilizing Dimensionless Parameters 195

11 Procedure and Applications of Sensitivity Analysis 199

12 Reaction Flow Analysis 211

13 Reaction Mechanisms of H2/O2 Systems 215

14 Gas-Phase Reaction Mechanisms of Aliphatic Hydrocarbon and Oxygen System 223

15 Reduction of Highly Complex Reaction System to Simpler Reaction Mechanisms 245

16 Formation Mechanism of Nitrogen Oxides 255

17 Formation and Control of CO and Particulates 270

References 274

Homework 281

3 The Conservation Equations for Multicomponent Reacting Systems

1 Definitions of Concentrations, Velocities, and Mass Fluxes 287

2 Fick’s Law of Diffusion 289

3 Theory of Ordinary Diffusion in Gases at Low Density 290

4 Continuity Equation and Species Mass Conservation Equations 293

5 Conservation of Momentum 297

6 Conservation of Energy 320

7 Physical Derivation of the Multicomponent Diffusion Equation 328

8 Other Necessary Equations in Multicomponent Systems 331

9 Solution of a Multicomponent-Species System 331

10 Shvab–Zel’dovich Formulation 332

11 Dimensionless Ratios of Transport Coefficients 336

12 Boundary Conditions at an Interface 337

References 350

Homework 350

Projects 353

4 Detonation and Deflagration Waves of Premixed Gases 354

Nomenclature 354

1 Qualitative Differences Between Detonation and Deflagration 356

2 The Hugoniot Curve 357

3 Properties of the Hugoniot Curve 361

4 Determination of Chapman–Jouguet Detonation Wave Velocity 373

5 Detonation-Wave Structure 381

6 The Mechanism of Deflagration-to-Detonation Transition (DDT) in Gaseous Mixtures 388

7 Detonability and Chemical Kinetics: Limits of Detonability 395

8 Nonideal Detonations 413

9 Consideration of Spontaneous Detonation Initiation 422

References 428

Homework 434

Project 435

5 Premixed Laminar Flames 437

Nomenclature 437

1 Introduction and Flame Speed Measurement Methods 438

2 Classical Laminar-Flame Theories 449

3 Contemporary Method for Solving Laminar-Flame Problems 461

4 Dynamic Analysis of Stretched Laminar Premix Flames 471

5 Effect of Chemical and Physical Variables on Flame Speed 496

6 Principle of Stabilization of Combustion Waves in Laminar Streams 503

7 Flame Quenching 507

8 Flammability Limits of Premixed Laminar Flames 510

References 528

Homework 533

Project 535

6 Gaseous Diffusion Flames and Combustion of a Single Liquid Fuel Droplet 537

Nomenclature 537

1 Burke and Schumann’s Theory of Laminar Diffusion Flames 539

2 Phenomenological Analysis of Fuel Jets 548

3 Laminar Diffusion Flame Jets 551

4 Evaporation and Burning of a Single Droplet in a Quiescent Atmosphere 569

5 Fuel Droplet in a Convective Stream 581

6 Supercritical Burning of Liquid Droplets in a Stagnant Environment 590

References 614

Homework 618

Projects 620

Appendix A Evaluation of Thermal and Transport Properties of Gases and Liquids 623

Nomenclature 623

Introduction 625

1 Gas Density 625

2 Liquid Density 633

3 Gas Specific Heat 641

4 Liquid Specific Heat 651

5 Gas Viscosity 654

6 Liquid Viscosity 661

7 Gas Thermal Conductivity 671

8 Liquid Thermal Conductivity 674

9 Gas Diffusivity 678

10 Liquid Diffusivity 684

References 688

Appendix B Constants and Conversion Factors Often Used in Combustion 693

Appendix C Naming of Hydrocarbons and Properties of Hydrocarbon Fuels 697

Appendix D Melting, Boiling, and Critical Temperatures of Elements 705

Appendix E Periodic Table and Electronic Configurations of Neutral Atoms in Ground States 707

Reference 711

Author Index 713

Subject Index 718