Saeed Farokhi, PhD, is Professor Emeritus of Aerospace Engineering at the University of Kansas, USA. His main areas of research focus are propulsion systems, flow control, renewable energy, and computational fluid dynamics. He is Fellow of the Royal Aeronautical Society and the American Society of Mechanical Engineers. He is Associate Fellow of the American Institute of Aeronautics and Astronautics.

Preface to the Third Edition xvii

Preface to the Second Edition xix

Preface to the First Edition xxi

About the Companion Website xxv

1 Introduction: Propulsion in Sustainable Aviation 1

1.1 History of the Airbreathing Jet Engine, a Twentieth-Century Invention-The Beginning 1

1.2 Innovations in Aircraft Gas Turbine Engines 4

1.2.1 Multispool Configuration 4

1.2.2 Variable Stator 5

1.2.3 Transonic Compressor 5

1.2.4 Low-Emission Combustor 6

1.2.5 Turbine Cooling 7

1.2.6 Exhaust Nozzles 8

1.2.7 Modern Materials and Manufacturing Techniques 8

1.3 Twenty-first Century Aviation Goal: Sustainability 10

1.3.1 Combustion Emissions 10

1.3.2 Greenhouse Gases 11

1.3.3 Fuels for Sustainable Aviation 14

1.4 New Engine Concepts in Sustainable Aviation 15

1.4.1 Advanced GT Concepts: ATP/CROR and GTF 15

1.4.2 Adaptive Cycle Engine 16

1.4.3 Advanced Airbreathing Rocket Technology 18

1.4.4 Wave Rotor Topping Cycle 18

1.4.4.1 Humphrey Cycle versus Brayton Cycle 18

1.4.5 Pulse Detonation Engine (PDE) 20

1.4.6 Millimeter-Scale Gas Turbine Engines: Triumph of MEMS and Digital Fabrication 20

1.4.7 Combined Cycle Propulsion: Engines from Takeoff to Space 21

1.4.8 Hybrid-Electric and Distributed Electric Propulsion 22

1.5 New Vehicle Technologies 30

1.6 Summary 34

1.7 Roadmap for the Third Edition 34

References 36

Problems 38

2 Compressible Flow with Friction and Heat: A Review 41

2.1 Introduction 41

2.2 A Brief Review of Thermodynamics 42

2.3 Isentropic Process and Isentropic Flow 46

2.4 Conservation Principles for Systems and Control Volumes 47

2.5 Speed of Sound and Mach Number 54

2.6 Stagnation State 56

2.7 Quasi-One-Dimensional Flow 58

2.8 Area-Mach Number Relationship 62

2.9 Sonic Throat 63

2.10 Waves in Supersonic Flow 66

2.11 Normal Shocks 67

2.12 Oblique Shocks 71

2.13 Conical Shocks 74

2.14 Expansion Waves 79

2.15 Frictionless, Constant-Area Duct Flow with Heat Transfer: Rayleigh Flow 83

2.16 Adiabatic Flow of a Calorically Perfect Gas in a Constant-Area Duct with Friction: Fanno Flow 92

2.17 Friction (drag) coefficient Cf and D'Arcy Friction Factor fD 105

2.18 Dimensionless Parameters 105

2.19 Fluid Impulse 108

2.20 Summary of Fluid Impulse 115

References 116

Problems 116

3 Engine Thrust and Performance Parameters 127

3.1 Introduction 127

3.1.1 Takeoff Thrust 133

3.2 Installed Thrust-Some Bookkeeping Issues on Thrust and Drag 133

3.3 Engine Thrust Based on the Sum of Component Impulse 138

3.4 Rocket Thrust 141

3.5 Airbreathing Engine Performance Parameters 142

3.5.1 Specific Thrust 142

3.5.2 Specific Fuel Consumption and Specific Impulse 143

3.5.3 Thermal Efficiency 144

3.5.4 Propulsive Efficiency 147

3.5.5 Engine Overall Efficiency and Its Impact on Aircraft Range and Endurance 150

3.6 Modern Engines, Their Architecture, and Some Performance Characteristics 153

3.7 Summary 156

References 157

Problems 158

4 Gas Turbine Engine Cycle Analysis 167

4.1 Introduction 167

4.2 The Gas Generator 167

4.3 Aircraft Gas Turbine Engines 169

4.3.1 The Turbojet Engine 169

4.3.1.1 The Inlet 169

4.3.1.2 The Compressor 173

4.3.1.3 The Burner 179

4.3.1.4 The Turbine 184

4.3.1.5 The Nozzle 193

4.3.1.6 Thermal Efficiency of a Turbojet Engine 200

4.3.1.7 Propulsive Efficiency of a Turbojet Engine 208

4.3.1.8 The Overall Efficiency of a Turbojet Engine 209

4.3.1.9 Performance Evaluation of a Turbojet Engine 210

4.3.2 The Turbojet Engine with an Afterburner 211

4.3.2.1 Introduction 211

4.3.2.2 Analysis 213

4.3.2.3 Optimum Compressor Pressure Ratio for Maximum (Ideal) Thrust Turbojet Engine with Afterburner 216

4.3.3 The Turbofan Engine 222

4.3.3.1 Introduction 222

4.3.3.2 Analysis of a Separate-Exhaust Turbofan Engine 223

4.3.3.3 Thermal Efficiency of a Turbofan Engine 227

4.3.3.4 Propulsive Efficiency of a Turbofan Engine 228

4.3.4 Ultra-High Bypass (UHB) Turbofan Engines 233

4.4 Analysis of a Mixed-Exhaust Turbofan Engine with an Afterburner 237

4.4.1 Mixer 238

4.4.2 Cycle Analysis 240

4.4.2.1 Solution Procedure 241

4.5 The Turboprop Engine 251

4.5.1 Introduction 251

4.5.2 Propeller Theory 252

4.5.2.1 Momentum Theory 253

4.5.2.2 Blade Element Theory 257

4.5.3 Turboprop Cycle Analysis 259

4.5.3.1 The New Parameters 259

4.5.3.2 Design Point Analysis 259

4.5.3.3 Optimum Power Split Between the Propeller and the Jet 263

4.6 Promising Propulsion and Power Technologies in Sustainable Aviation 269

4.6.1 Distributed Combustion Concepts in Advanced Gas Turbine Engine Core 269

4.6.2 Multi-Fuel (Cryogenic-Kerosene) Hybrid Propulsion Concept 272

4.6.3 Intercooled and Recuperated Turbofan Engines 274

4.6.4 Active Core Concepts 275

4.6.5 Wave-Rotor Combustion 277

4.6.6 Pulse Detonation Engine (PDE) 283

4.6.6.1 Idealized Laboratory PDE: Thrust Tube 285

4.6.6.2 Pulse Detonation Ramjet 286

4.6.6.3 Turbofan Engine with PDE 287

4.6.6.4 Pulse Detonation Rocket Engine (PDRE) 288

4.6.6.5 Vehicle-Level Performance Evaluation of PDE 288

4.6.7 Adaptive Cycle Engines (ACE) 290

4.7 Summary 294

References 295

Problems 297

5 General Aviation and Uninhabited Aerial Vehicle Propulsion System 319

5.1 Introduction 319

5.2 Cycle Analysis 320

5.2.1 Otto Cycle 320

5.2.2 Real Engine Cycles 320

5.2.2.1 Four-Stroke Cycle Engines 320

5.2.2.2 Diesel Engines 322

5.2.2.3 Two-Stroke Cycle Engines 324

5.2.2.4 Rotary (Wankel) Engines 326

5.3 Power and Efficiency 328

5.4 Engine Components and Classifications 330

5.4.1 Engine Components 330

5.4.2 Reciprocating Engine Classifications 331

5.4.2.1 Classification by Cylinder Arrangement 331

5.4.2.2 Classification by Cooling Arrangement 333

5.4.2.3 Classification by Operating Cycle 334

5.4.2.4 Classification by Ignition Type 334

5.5 Scaling of Aircraft Reciprocating Engines 335

5.5.1 Scaling of Aircraft Diesel Engines 341

5.6 Aircraft Engine Systems 343

5.6.1 Aviation Fuels and Engine Knock 343

5.6.2 Carburetion and Fuel Injection Systems 345

5.6.2.1 Float-Type Carburetors 345

5.6.2.2 Pressure Injection Carburetors 346

5.6.2.3 Fuel Injection Systems 346

5.6.2.4 Full Authority Digital Engine Control (FADEC) 346

5.6.3 Ignition Systems 346

5.6.3.1 Battery Ignition Systems 347

5.6.3.2 High Tension Ignition System 347

5.6.3.3 Low Tension Ignition System 347

5.6.3.4 Full Authority Digital Engine Control (FADEC) 347

5.6.3.5 Ignition Boosters 347

5.6.3.6 Spark Plugs 348

5.6.4 Lubrication Systems 348

5.6.5 Supercharging 349

5.7 Electric Engines 349

5.7.1 Electric Motors 350

5.7.2 Solar cells 351

5.7.3 Advanced Batteries 351

5.7.4 Fuel cells 352

5.7.5 State of the Art for Electric Propulsion - Future Technology 354

5.8 Propellers and Reduction Gears 354

References 356

Problems 359

6 Aircraft Engine Inlets and Nozzles 361

6.1 Introduction 361

6.2 The Flight Mach Number and its Impact on Inlet Duct Geometry 362

6.3 Diffusers 363

6.4 An Ideal Diffuser 364

6.5 Real Diffusers and their Stall Characteristics 365

6.6 Subsonic Diffuser Performance 367

6.7 Subsonic Cruise Inlet 372

6.8 Transition Ducts 380

6.9 An Interim Summary for Subsonic Inlets 381

6.10 Supersonic Inlets 382

6.10.1 Isentropic Convergent-Divergent Inlets 383

6.10.2 Methods to Start a Supersonic Convergent-Divergent Inlet 385

6.10.2.1 Overspeeding 386

6.10.2.2 Kantrowitz-Donaldson Inlet 388

6.10.2.3 Variable-Throat Isentropic C-D Inlet 389

6.11 Normal Shock Inlets 391

6.12 External Compression Inlets 393

6.12.1 Optimum Ramp Angles 396

6.12.2 Design and Off-Design Operation 396

6.13 Variable Geometry-External Compression Inlets 398

6.13.1 Variable Ramps 399

6.14 Mixed-Compression Inlets 399

6.15 Supersonic Inlet Types and their Performance-A Review 401

6.16 Standards for Supersonic Inlet Recovery 402

6.17 Exhaust Nozzle 404

6.18 Gross Thrust 404

6.19 Nozzle Adiabatic Efficiency 404

6.20 Nozzle Total Pressure Ratio 405

6.21 Nozzle Pressure Ratio (NPR) and Critical Nozzle Pressure Ratio (NPRcrit) 405

6.22 Relation between Nozzle Figures of Merit, ¿n and ¿n 406

6.23 A Convergent Nozzle or a De Laval? 407

6.24 The Effect of Boundary Layer Formation on Nozzle Internal Performance 409

6.25 Nozzle Exit Flow Velocity Coefficient 409

6.26 Effect of Flow Angularity on Gross Thrust 411

6.27 Nozzle Gross Thrust Coefficient Cfg 414

6.28 Over-Expanded Nozzle Flow-Shock Losses 415

6.29 Nozzle Area Scheduling, A8 and A9 /A8 418

6.30 Nozzle Exit Area Scheduling, A9 /A8 420

6.31 Nozzle Cooling 422

6.32 Thrust Reverser and Thrust Vectoring 424

6.33 Hypersonic Nozzle 429

6.34 Exhaust Mixer and Gross Thrust Gain in a Mixed-Flow Turbofan Engine 432

6.35 Engine Noise 434

6.35.1 Subsonic Jet Noise...