Preface xiii
Acknowledgments xvii
Abbreviations and Acronyms xix
About the Companion Website xxvii
1 Aircraft Engines – A Review 1
1.1 Introduction 1
1.2 Aerothermodynamics of Working Fluid 1
1.2.1 Isentropic Process and Isentropic Flow 6
1.2.2 Conservation of Mass 6
1.2.3 Conservation of Linear Momentum 7
1.2.4 Conservation of Angular Momentum 7
1.2.5 Conservation of Energy 8
1.2.6 Speed of Sound and Mach Number 10
1.2.7 Stagnation State 11
1.3 Thrust and Specific Fuel Consumption 12
1.3.1 Takeoff Thrust 16
1.3.2 Installed Thrust – Some Bookkeeping Issues on Thrust and Drag 16
1.3.3 Air?Breathing Engine Performance Parameters 18
1.3.3.1 Specific Thrust 18
1.3.3.2 Specific Fuel Consumption and Specific Impulse 19
1.4 Thermal and Propulsive Efficiency 20
1.4.1 Thermal Efficiency 20
1.4.2 Propulsive Efficiency 22
1.4.3 Engine Overall Efficiency and Its Impact on Aircraft Range and Endurance 24
1.5 Gas Generator 27
1.6 Engine Components 28
1.6.1 The Inlet 28
1.6.2 The Nozzle 30
1.6.3 The Compressor 36
1.6.4 The Combustor 40
1.6.5 The Turbine 44
1.7 Performance Evaluation of a Turbojet Engine 52
1.8 Turbojet Engine with an Afterburner 54
1.8.1 Introduction 54
1.8.2 Analysis 56
1.9 Turbofan Engine 59
1.9.1 Introduction 59
1.9.2 Analysis of a Separate?Exhaust Turbofan Engine 60
1.9.3 Thermal Efficiency of a Turbofan Engine 64
1.9.4 Propulsive Efficiency of a Turbofan Engine 65
1.9.5 Ultra?High Bypass (UHB) Geared Turbofan Engines 69
1.9.6 Analysis of Mixed?Exhaust Turbofan Engines with Afterburners 73
1.9.6.1 Mixer 74
1.9.6.2 Mixed?Turbofan Cycle Analysis 76
1.9.6.3 Solution Procedure 77
1.10 Turboprop Engine 84
1.10.1 Introduction 84
1.10.2 Turboprop Cycle Analysis 85
1.10.2.1 The New Parameters 85
1.10.2.2 Design?Point Analysis 86
1.10.2.3 Optimum Power Split between the Propeller and the Jet 90
1.10.2.4 Advanced Propeller: Prop?Fan 94
1.11 High?Speed Air?Breathing Engines 95
1.11.1 Supersonic Combustion Ramjet 99
1.11.1.1 Inlet Analysis 99
1.11.1.2 Scramjet Combustor 101
1.11.1.3 Scramjet Nozzle 103
1.12 Rocket?Based Airbreathing Propulsion 103
1.13 Summary 104
References 105
2 Aircraft Aerodynamics – A Review 109
2.1 Introduction 109
2.2 Similarity Parameters in Compressible Flow: Flight vs. Wind Tunnel 111
2.3 Physical Boundary Conditions on a Solid Wall (in Continuum Mechanics) 113
2.4 Profile and Parasite Drag 115
2.4.1 Boundary Layers 115
2.4.1.1 Case 1: Incompressible Laminar Flow 116
2.4.1.2 Case 2: Laminar Compressible Boundary Layers 125
2.4.1.3 Case 3: Turbulent Boundary Layers 129
2.4.1.4 Case 4: Transition 132
2.4.2 Profile Drag of an Airfoil 135
2.5 Drag Due to Lift 141
2.5.1 Classical Theory 141
2.5.2 Optimal Spanloading: The Case of Bell Spanload 147
2.6 Waves in Supersonic Flow 150
2.6.1 Speed of Sound 150
2.6.2 Normal Shock Wave 152
2.6.3 Oblique Shock Waves 152
2.6.4 Expansion Waves 155
2.7 Compressibility Effects and Critical Mach Number 157
2.8 Drag Divergence Phenomenon and Supercritical Airfoil 161
2.9 Wing Sweep 163
2.10 Delta Wing Aerodynamics 166
2.10.1 Vortex Breakdown 167
2.11 Area?Rule in Transonic Aircraft 169
2.12 Optimum Shape for Slender Body of Revolution of Length ? in Supersonic Flow 171
2.12.1 Sears?Haack Body 174
2.12.2 Von Karman Ogive of Length ? and Base Area, S(?), for Minimum Axisymmetric Nose Wave Drag 175
2.13 High?Lift Devices: Multi?Element Airfoils 175
2.14 Powered Lift and STOL Aircraft 179
2.15 Laminar Flow Control, LFC 180
2.16 Aerodynamic Figures of Merit 182
2.17 Advanced Aircraft Designs and Technologies for Leaner, Greener Aviation 188
2.18 Summary 194
References 195
3 Understanding Aviation’s Impact on the Environment 201
3.1 Introduction 201
3.2 Combustion Emissions 202
3.2.1 Greenhouse Gases 202
3.2.2 Carbon Monoxide, CO, and Unburned Hydrocarbons, UHC 205
3.2.3 Oxides of Nitrogen, NOx 208
3.2.4 Impact of NO on Ozone in Lower and Upper Atmosphere 209
3.2.4.1 Lower Atmosphere 209
3.2.4.2 Upper Atmosphere 211
3.2.5 Impact of NOx Emissions on Surface Air Quality 213
3.2.6 Soot/Smoke and Particulate Matter (PM) 214
3.2.7 Contrails, Cirrus Clouds, and Impact on Climate 215
3.3 Engine Emission Standards 215
3.4 Low?Emission Combustors 216
3.5 Aviation Fuels 219
3.6 Interim Summary on Combustion Emission Impact on the Environment 225
3.7 Aviation Impact on Carbon Dioxide Emission: Quantified 227
3.8 Noise 232
3.8.1 Introduction 232
3.8.1.1 General Discussion 232
3.8.1.2 Sound Intensity 236
3.8.1.3 Acoustic Power 236
3.8.1.4 Levels and Decibels 237
3.8.1.5 Sound Power Level in Decibels, dB 237
3.8.1.6 Sound Intensity Level in Decibels, dB 237
3.8.1.7 Sound Pressure Level in Decibels, dB 237
3.8.1.8 Multiple Sources 237
3.8.1.9 Overall Sound Pressure Level in Decibels, dB 238
3.8.1.10 Octave Band, One?Third Octave Band, and Tunable Filters 238
3.8.1.11 Adding and Subtracting Noise Sources 239
3.8.1.12 Weighting 239
3.8.1.13 Effective Perceived Noise Level (EPNL), dB, and Other Metrics 240
3.8.1.14 Pulsating Sphere: Model of a Monopole 241
3.8.1.15 Two Monopoles: Model of a Dipole 242
3.8.1.16 Two Dipoles: Model of Quadrupole 243
3.8.2 Sources of Noise Near Airports 244
3.8.3 Engine Noise 245
3.8.4 Subsonic Jet Noise 249
3.8.5 Supersonic Jet Noise 251
3.9 Engine Noise Directivity Pattern 253
3.10 Noise Reduction at the Source 256
3.10.1 Wing Shielding 256
3.10.2 Fan Noise Reduction 256
3.10.3 Subsonic Jet Noise Mitigation 260
3.10.3.1 Chevron Nozzle 260
3.10.3.2 Acoustic Liner in Exhaust Core 261
3.10.4 Supersonic Jet Noise Reduction 262
3.11 Sonic Boom 263
3.12 Aircraft Noise Certification 268
3.13 NASA’s Vision: Quiet Green Transport Technology 272
3.14 FAA’s Vision: NextGen Technology 273
3.15 The European Vision for Sustainable Aviation 274
3.16 Summary 275
References 276
4 Future Fuels and Energy Sources in Sustainable Aviation 283
4.1 Introduction 283
4.2 Alternative Jet Fuels (AJFs) 288
4.2.1 Choice of Feedstock 291
4.2.2 Conversion Pathways to Jet Fuel 292
4.2.3 AJF Evaluation and Certification/Qualification 293
4.2.4 Impact of Biofuel on Emissions 294
4.2.5 Advanced Biofuel Production 296
4.2.6 Lifecycle Assessment of Bio?Based Aviation Fuel 303
4.2.7 Conversion of Bio?Crops to Electricity 305
4.3 Liquefied Natural Gas, LNG 305
4.3.1 Composition of Natural Gas and LNG 307
4.4 Hydrogen 308
4.4.1 Hydrogen Production 310
4.4.2 Hydrogen Delivery and Storage 312
4.4.3 Gravimetric and Volumetric Energy Density and Liquid Fuel Cost 312
4.5 Battery Systems 312
4.5.1 Battery Energy Density 314
4.5.2 Open?Cycle Battery Systems 315
4.5.3 Charging Batteries in Flight: Two Examples 316
4.5.4 All?Electric Aircraft: Voltair Concept Platform 316
4.6 Fuel Cell 318
4.7 Fuels for the Compact Fusion Reactor (CFR) 320
4.8 Summary 321
References 322
5 Promising Technologies in Propulsion and Power 325
5.1 Introduction 325
5.2 Gas Turbine Engine 326
5.2.1 Brayton Cycle: Simple Gas Turbine Engine 326
5.2.2 Turbofan Engine 327
5.3 Distributed Combustion Concepts in Advanced Gas Turbine Engine Core 330
5.4 Multifuel (Cryogenic?Kerosene), Hybrid Propulsion Concept 335
5.5 Intercooled and Recuperated Turbofan Engines 335
5.6 Active Core Concepts 340
5.7 Topping Cycle: Wave Rotor Combustion 340
5.8 Pulse Detonation Engine (PDE) 351
5.9 Humphrey Cycle vs. Brayton: Thermodynamics 351
5.9.1 Idealized Laboratory PDE: Thrust Tube 353
5.9.2 Pulse Detonation Ramjets 355
5.9.3 Turbofan Engine with PDE 356
5.9.4 Pulse Detonation Rocket Engine (PDRE) 357
5.9.5 Vehicle?Level Performance Evaluation of PDE 358
5.10 Boundary?Layer Ingestion (BLI) and Distributed Propulsion (DP) Concept 358
5.10.1 Aircraft Drag Reduction Through BLI 360
5.10.2 Aircraft Noise Reduction: Advanced Concepts 362
5.10.3 Multidisciplinary Design Optimization (MDO) of a BWB Aircraft with BLI 365
5.11 Distributed Propulsion Concept in Early Aviation 367
5.12 Distributed Propulsion in Modern Aviation 368
5.12.1 Optimal Number of Propulsors in Distributed Propulsion 371
5.12.2 Optimal Propulsor Types in Distributed Propulsion 372
5.13 Interim Summary on Electric Propulsion (EP) 384
5.14 Synergetic Air?Breathing Rocket Engine; SABRE 386
5.15 Compact Fusion Reactor: The Path to Clean, Unlimited Energy 388
5.16 Aircraft Configurations Using Advanced Propulsion Systems 389
5.17 Summary 395
References 396
6 Pathways to Sustainable Aviation 403
6.1 Introduction 403
6.2 Pathways to Certification 403
6.3 Energy Pathways in Sustainable Aviation 405
6.4 Future of GT Engines 407
6.5 Summary 409
References 410
Index 411
