Gas Turbine Propulsion Systems

About the Authors x Preface xii Series Preface xiv Acknowledgements xvi List of Acronyms xviii 1 Introduction 1 1.1 Gas Turbine Concepts 1 1.2 Gas Turbine Systems Overview 6 References 9 2 Basic Gas Turbine Operation 11 2.1 Turbojet Engine Performance 11 2.1.1 Engine Performance Characteristics 18 2.1.2 Compressor Surge Control 22 2.1.3 Variable Nozzles 28 2.2 Concluding Commentary 35 References 35 3 Gas Generator Fuel Control Systems 37 3.1 Basic Concepts of the Gas Generator Fuel Control System 37 3.2 Gas Generator Control Modes 40 3.2.1 Fuel Schedule Definition 42 3.2.2 Overall Gas Generator Control Logic 45 3.2.3 Speed Governing with Acceleration and Deceleration Limiting 46 3.2.4 Compressor Geometry Control 62 3.2.5 Turbine Gas Temperature Limiting 63 3.2.6 Overspeed Limiting 65 3.3 Fuel System Design and Implementation 65 3.3.1 A Historical Review of Fuel Control Technologies 67 3.3.2 Fuel Pumping and Metering Systems 72 3.4 The Concept of Error Budgets in Control Design 77 3.4.1 Measurement Uncertainty 79 3.4.2 Sources of Error 80 3.5 Installation, Qualification, and Certification Considerations 84 3.5.1 Fuel Handling Equipment 84 3.5.2 Full-authority Digital Engine Controls (FADEC) 86 3.6 Concluding Commentary 88 References 88 4 Thrust Engine Control and Augmentation Systems 89 4.1 Thrust Engine Concepts 89 4.2 Thrust Management and Control 92 4.3 Thrust Augmentation 95 4.3.1 Water Injection 96 4.3.2 Afterburning 97 Reference 103 5 Shaft Power Propulsion Control Systems 105 5.1 Turboprop Applications 110 5.1.1 The Single-shaft Engine 110 5.1.2 The Free Turbine Turboprop 112 5.2 Turboshaft Engine Applications 119 Reference 130 6 Engine Inlet, Exhaust, and Nacelle Systems 131 6.1 Subsonic Engine Air Inlets 131 6.1.1 Basic Principles 132 6.1.2 Turboprop Inlet Configurations 133 6.1.3 Inlet Filtration Systems 135 6.2 Supersonic Engine Air Inlets 136 6.2.1 Oblique Shockwaves 137 6.2.2 Combined Oblique/Normal Shock Pressure Recovery Systems 139 6.2.3 Supersonic Inlet Control 141 6.2.4 Overall System Development and Operation 143 6.2.5 Concorde Air Inlet Control System (AICS) Example 144 6.3 Inlet Anti-icing 150 6.3.1 Bleed-air Anti-icing Systems 151 6.3.2 Electrical Anti-icing Systems 151 6.4 Exhaust Systems 151 6.4.1 Thrust Reversing Systems 152 6.4.2 Thrust Vectoring Concepts 155 References 160 7 Lubrication Systems 161 7.1 Basic Principles 161 7.2 Lubrication System Operation 169 7.2.1 System Design Concept 170 7.2.2 System Design Considerations 174 7.2.3 System Monitoring 174 7.2.4 Ceramic Bearings 179 References 179 8 Power Extraction and Starting Systems 181 8.1 Mechanical Power Extraction 181 8.1.1 Fuel Control Systems Equipment 181 8.1.2 Hydraulic Power Extraction 183 8.1.3 Lubrication and Scavenge Pumps 184 8.1.4 Electrical Power Generation 184 8.2 Engine Starting 187 8.3 Bleed-air-powered Systems and Equipment 189 8.3.1 Bleed-air-driven Pumps 191 8.3.2 Bleed Air for Environmental Control, Pressurization and Anti-icing Systems 192 8.3.3 Fuel Tank Inerting 193 References 194 9 Marine Propulsion Systems 195 9.1 Propulsion System Designation 197 9.2 The Aero-derivative Gas Turbine Engine 198 9.3 The Marine Environment 199 9.3.1 Marine Propulsion Inlets 200 9.3.2 Marine Exhaust Systems 203 9.3.3 Marine Propellers 204 9.4 The Engine Enclosure 206 9.4.1 The Engine Support System 207 9.4.2 Enclosure Air Handling 208 9.4.3 Enclosure Protection 208 9.5 Engine Ancillary Equipment 209 9.5.1 Engine Starting System 209 9.5.2 Engine Lubrication System 211 9.5.3 Fuel Supply System 212 9.6 Marine Propulsion Control 214 9.6.1 Ship Operations 214 9.6.2 Overall Propulsion Control 217 9.6.3 Propulsion System Monitoring 219 9.6.4 Propulsion System Controller 222 9.6.5 Propulsion System Sequencer 224 9.7 Concluding Commentary 224 References 225 10 Prognostics and Health Monitoring Systems 227 10.1 Basic Concepts in Engine Operational Support Systems 229 10.1.1 Material Life Limits 229 10.1.2 Performance-related Issues 232 10.1.3 Unscheduled Events 234 10.2 The Role of Design in Engine Maintenance 234 10.2.1 Reliability 235 10.2.2 Maintainability 237 10.2.3 Availability 239 10.2.4 Failure Mode, Effects, and Criticality Analysis 241 10.3 Prognostics and Health Monitoring (PHM) 243 10.3.1 The Concept of a Diagnostic Algorithm 244 10.3.2 Qualification of a Fault Indicator 245 10.3.3 The Element of Time in Diagnostics 250 10.3.4 Data Management Issues 251 References 255 11 New and Future Gas Turbine Propulsion System Technologies 257 11.1 Thermal Efficiency 257 11.2 Improvements in Propulsive Efficiency 260 11.2.1 The Pratt & Whitney PW1000G Geared Turbofan Engine 261 11.2.2 The CFM International Leap Engine 264 11.2.3 The Propfan Concept 265 11.3 Other Engine Technology Initiatives 268 11.3.1 The Boeing 787 Bleedless Engine Concept 268 11.3.2 New Engine Systems Technologies 271 11.3.3 Emergency Power Generation 276 11.3.4 On-board Diagnostics 277 References 277 Appendix A Compressor Stage Performance 279 A.1 The Origin of Compressor Stage Characteristics 279 A.2 Energy Transfer from Rotor to Air 281 References 284 Appendix B Estimation of Compressor Maps 285 B.1 Design Point Analysis 288 B.2 Stage Stacking Analysis 291 References 293 Appendix C Thermodynamic Modeling of Gas Turbines 295 C.1 Linear Small-perturbation Modeling 295 C.1.1 Rotor Dynamics 296 C.1.2 Rotor Dynamics with Pressure Term 297 C.1.3 Pressure Dynamics 298 C.2 Full-range Model: Extended Linear Approach 298 C.3 Component-based Thermodynamic Models 299 C.3.1 Inlet 301 C.3.2 Compressor 302 C.3.3 Combustor 302 C.3.4 Turbine 304 C.3.5 Jet Pipe 305 C.3.6 Nozzle 306 C.3.7 Rotor 306 References 306 Appendix D Introduction to Classical Feedback Control 307 D.1 Closing the Loop 307 D.2 Block Diagrams and Transfer Functions 308 D.3 The Concept of Stability 310 D.3.1 The Rule for Stability 310 D.4 Frequency Response 311 D.4.1 Calculating Frequency Response 311 D.5 Laplace Transforms 315 D.5.1 Root Locus 317 D.5.2 Root Locus Construction Rules 318 Reference 321 Index 323