Aircraft Propulsion – Cleaner, Leaner, and Greener 3rd Edition

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 Preface to the Second Edition Preface to the First Edition 1. Introduction 1.1 History of the Airbreathing Jet Engine, a Twentieth-Century Invention--The Beginning 1.2 Innovations in Aircraft Gas Turbine Engines 1.2.1 Multispool Configuration 1.2.2 Variable Stator 1.2.3 Transonic Compressor 1.2.4 Low-Emission Combustor 1.2.5 Turbine Cooling 1.2.6 Exhaust Nozzles 1.2.7 Modern Materials and Manufacturing Techniques 1.3 Twenty-first Century Aviation Goal: Sustainability 1.3.1 Combustion Emissions 1.3.2 Greenhouse Gases 1.3.3 Fuels for Sustainable Aviation 1.4 New Engine Concepts in Sustainable Aviation 1.4.1 Advanced GT Concepts: ATP/CROR and GTF 1.4.2 Adaptive Cycle Engine 1.4.3 Advanced Airbreathing Rocket Technology 1.4.4 Wave Rotor Topping Cycle 1.4.5 Pulse Detonation Engine (PDE) 1.4.6 Millimeter-Scale Gas Turbine Engines: Triumph of MEMS and Digital Fabrication 1.4.7 Combined Cycle Propulsion: Engines from Takeoff to Space 1.4.8 Hybrid-Electric and Distributed Electric Propulsion 1.5 New Vehicle Technologies 1.6 Summary 1.7 Roadmap for the Third Edition References Problems 2. Compressible Flow with Heat and Friction: A Review 2.1 Introduction 2.2 A Brief Review of Thermodynamics 2.3 Isentropic Process and Isentropic Flow 2.4 Conservation Principles for Systems and Control Volumes 2.5 Speed of Sound & Mach Number 2.6 Stagnation State 2.7 Quasi-One-Dimensional Flow 2.8 Area-Mach Number Relationship 2.9 Sonic Throat 2.10 Waves in Supersonic Flow 2.11 Normal Shocks 2.12 Oblique Shocks 2.13 Conical Shocks 2.14 Expansion Waves 2.15 Frictionless, Constant-Area Duct Flow with Heat Transfer: Rayleigh Flow 2.16 Adiabatic Flow of a Calorically Perfect Gas in a Constant-Area Duct with Friction: Fanno Flow 2.17 Friction (Drag) Coefficient Cf and D'Arcy Friction Factor fD 2.18 Dimensionless Parameters 2.19 Fluid Impulse 2.20 Summary of Fluid Impulse References Problems 3. Engine Thrust and Performance Parameters 3.1 Introduction 3.1.1 Takeoff Thrust 3.2 Installed Thrust--Some Bookkeeping Issues on Thrust and Drag 3.3 Engine Thrust Based on the Sum of Component Impulse 3.4 Rocket Thrust 3.5 Airbreathing Engine Performance Parameters 3.5.1 Specific Thrust 3.5.2 Specific Fuel Consumption and Specific Impulse 3.5.3 Thermal Efficiency 3.5.4 Propulsive Efficiency 3.5.5 Engine Overall Efficiency and Its Impact on Aircraft Range and Endurance 3.6 Modern Engines, Their Architecture, and Some Performance Characteristics 3.7 Summary References Problems 4. Gas Turbine Engine Cycle Analysis 4.1 Introduction 4.2 The Gas Generator 4.3 Aircraft Gas Turbine Engines 4.3.1 The Turbojet Engine 4.3.1.1 The Inlet 4.3.1.2 The Compressor 4.3.1.3 The Burner 4.3.1.4 The Turbine 4.3.1.5 The Nozzle 4.3.1.6 Thermal Efficiency of a Turbojet Engine 4.3.1.7 Propulsive Efficiency of a Turbojet Engine 4.3.1.8 The Overall Efficiency of a Turbojet Engine 4.3.1.9 Performance Evaluation of a Turbojet Engine 4.3.2 The Turbojet Engine with an Afterburner 4.3.2.1 Introduction 4.3.2.2 Analysis 4.3.2.3 Optimum Compressor Pressure Ratio for Maximum (Ideal) Thrust Turbojet Engine with Afterburner 4.3.3 The Turbofan Engine 4.3.3.1 Introduction 4.3.3.2 Analysis of a Separate-Exhaust Turbofan Engine 4.3.3.3 Thermal Efficiency of a Turbofan Engine 4.3.3.4 Propulsive Efficiency of a Turbofan Engine 4.3.4 Ultra-High Bypass (UHB) Turbofan Engines 4.4 Analysis of a Mixed-Exhaust Turbofan Engine with an Afterburner 4.4.1 Mixer 4.4.2 Cycle Analysis 4.4.2.1 Solution Procedure 4.5 The Turboprop Engine 4.5.1 Introduction 4.5.2 Propeller Theory 4.5.2.1 Momentum Theory 4.5.2.2 Blade Element Theory 4.5.3 Turboprop Cycle Analysis 4.5.3.1 The New Parameters 4.5.3.2 Design Point Analysis 4.5.3.3 Optimum Power Split Between the Propeller and the Jet 4.6 Promising Propulsion and Power Technologies in Sustainable Aviation 4.6.1 Distributed Combustion Concepts in Advanced Gas Turbine Engine Core 4.6.2 Multi-Fuel (Cryogenic-Kerosene) Hybrid Propulsion Concept 4.6.3 Intercooled and Recuperated Turbofan Engines 4.6.4 Active Core Concepts 4.6.5 Wave Rotor Combustion 4.6.6 Pulse Detonation Engine (PDE) 4.6.6.1 Idealized Laboratory PDE: Thrust Tube 4.6.6.2 Pulse Detonation Ramjet 4.6.6.3 Turbofan Engine with PDE 4.6.6.4 Pulse Detonation Rocket Engine (PDRE) 4.6.6.5 Vehicle-Level Performance Evaluation of PDE 4.6.7 Adaptive Cycle Engines (ACE) 4.7 Summary References Problems 5. General Aviation and Uninhabited Aerial Vehicle Propulsion System 5.1 Introduction 5.2 Cycle Analysis 5.2.1 Otto Cycle 5.2.2 Real Engine Cycles 5.2.2.1 Four-Stroke Cycle Engines 5.2.2.2 Diesel Engines 5.2.2.3 Two-Stroke Cycle Engines 5.2.2.4 Rotary (Wankel) Engines 5.3 Power and Efficiency 5.4 Engine Components and Classifications 5.4.1 Engine Components 5.4.2 Reciprocating Engine Classifications 5.4.2.1 Classification by Cylinder Arrangement 5.4.2.2 Classification by Cooling Arrangement 5.4.2.3 Classification by Operating Cycle 5.4.2.4 Classification by Ignition Type 5.5 Scaling of Aircraft Reciprocating Engines 5.5.1 Scaling of Aircraft Diesel Engines 5.6 Aircraft Engine Systems 5.6.1 Aviation Fuels and Engine Knock 5.6.2 Carburetion and Fuel Injection Systems 5.6.2.1 Float-Type Carburetors 5.6.2.2 Pressure Injection Carburetors 5.6.2.3 Fuel Injection Systems 5.6.2.4 Full Authority Digital Engine Control (FADEC) 5.6.3 Ignition Systems 5.6.3.1 Battery Ignition Systems 5.6.3.2 High Tension Ignition System 5.6.3.3 Low Tension Ignition System 5.6.3.4 Full Authority Digital Engine Control (FADEC) 5.6.3.5 Ignition Boosters 5.6.3.6 Spark Plugs 5.6.4 Lubrication Systems 5.6.5 Supercharging 5.7 Electric Engines 5.7.1 Electric Motors 5.7.2 Solar cells 5.7.3 Advanced Batteries 5.7.4 Fuel cells 5.7.5 State of the Art for Electric Propulsion - Future Technology 5.8 Propellers and Reduction Gears References Problems 6. Aircraft Engine Inlets and Nozzles 6.1 Introduction 6.2 The Flight Mach Number and its Impact on Inlet Duct Geometry 6.3 Diffusers 6.4 An Ideal Diffuser 6.5 Real Diffusers and their Stall Characteristics 6.6 Subsonic Diffuser Performance 6.7 Subsonic Cruise Inlet 6.8 Transition Ducts 6.9 An Interim Summary for Subsonic Inlets 6.10 Supersonic Inlets 6.10.1 Isentropic Convergent-Divergent Inlets 6.10.2 Methods to Start a Supersonic Convergent-Divergent Inlet 6.10.2.1 Overspeeding 6.10.2.2 Kantrowitz-Donaldson Inlet 6.10.2.3 Variable-Throat Isentropic C-D Inlet 6.11 Normal Shock Inlets 6.12 External Compression Inlets 6.12.1 Optimum Ramp Angles 6.12.2 Design and Off-Design Operation 6.13 Variable Geometry--External Compression Inlets 6.13.1 Variable Ramps 6.14 Mixed-Compression Inlets 6.15 Supersonic Inlet Types and their Performance--A Review 6.16 Standards for Supersonic Inlet Recovery 6.17 Exhaust Nozzle 6.18 Gross Thrust 6.19 Nozzle Adiabatic Efficiency 6.20 Nozzle Total Pressure Ratio 6.21 Nozzle Pressure Ratio (NPR) and Critical Nozzle Pressure Ratio (NPRcrit.) 6.22 Relation between Nozzle Figures of Merit, eta n and pi n 6.23 A Convergent Nozzle or a De Laval? 6.24 The Effect of Boundary Layer Formation on Nozzle Internal Performance 6.25 Nozzle Exit Flow Velocity Coefficient 6.26 Effect of Flow Angularity on Gross Thrust 6.27 Nozzle Gross Thrust Coefficient Cfg 6.28 Overexpanded Nozzle Flow--Shock Losses 6.29 Nozzle Area Scheduling, A8 and A9/A8 6.30 Nozzle Exit Area Scheduling, A9/A8 6.31 Nozzle Cooling 6.32 Thrust Reverser and Thrust Vectoring 6.33 Hypersonic Nozzle 6.34 Exhaust Mixer and Gross Thrust Gain in a Mixed-Flow Turbofan Engine 6.35 Engine Noise 6.35.1 Subsonic Jet Noise 6.35.2 Chevron Nozzle 6.35.3 Supersonic Jet Noise 6.35.4 Engine Noise Mitigation through Wing Shielding 6.36 Nozzle-Turbine (Structural) Integration 6.37 Summary of Exhaust Systems References Problems 7. Combustion Chambers and Afterburners 7.1 Introduction 7.2 Laws Governing Mixture of Gases 7.3 Chemical Reaction and Flame Temperature 7.4 Chemical Equilibrium and Chemical Composition 7.4.1 The Law of Mass Action 7.4.2 Equilibrium Constant KP 7.5 Chemical Kinetics 7.5.1 Ignition and Relight Envelope 7.5.2 Reaction Timescale 7.5.3 Flammability Limits 7.5.4 Flame Speed 7.5.5 Flame Stability 7.5.6 Spontaneous Ignition Delay Time 7.5.7 Combustion-Generated Pollutants 7.6 Combustion Chamber 7.6.1 Combustion Chamber Total Pressure Loss 7.6.2 Combustor Flow Pattern and Temperature Profile 7.6.3 Combustor Liner and its Cooling Methods 7.6.4 Combustion Efficiency 7.6.5 Some Combustor Sizing and Scaling Laws 7.6.6 Afterburner 7.7 Combustion-Generated Pollutants 7.7.1 Greenhouse Gases, CO2 and H2O 7.7.2 Carbon Monoxide, CO, and Unburned Hydrocarbons, UHC 7.7.3 Oxides of Nitrogen, NO and NO2 7.7.4 Smoke 7.7.5 Engine Emission Standards 7.7.6 Low-Emission Combustors 7.7.7 Impact of NO on the Ozone Layer 7.8 Aviation Fuels 7.9 Alternative Jet Fuels (AJFs) 7.9.1 Conversion Pathways to Jet Fuel 7.9.2 AJF Evaluation and Certification/Qualification 7.9.3 Impact of Biofuel on Emissions 7.10 Cryogenic Fuels 7.10.1 Liquefied Natural Gas (LNG) 7.10.1.1 Composition of Natural Gas and LNG 7.10.2 Hydrogen 7.10.2.1 Hydrogen Production 7.10.2.2 Hydrogen Delivery and Storage 7.10.3 Energy Density Comparison 7.11 Combustion Instability: Screech and Rumble 7.11.1 Screech Damper 7.12 Summary References Problems 8. Aerodynamics of Axial-Flow Compressors and Fans 8.1 Introduction 8.2 The Geometry 8.3 Rotor and Stator Frames of Reference 8.4 The Euler Turbine Equation 8.5 Axial-Flow Versus Radial-Flow Machines 8.6 Axial-Flow Compressors and Fans 8.6.1 Definition of Flow Angles 8.6.2 Stage Parameters 8.6.3 Cascade Aerodynamics 8.6.4 Aerodynamic Forces on Compressor Blades 8.6.5 Three-Dimensional Flow 8.6.5.1 Blade Vortex Design 8.6.5.2 Three-Dimensional Losses 8.6.5.3 Reynolds Number Effect 8.7 Compressor Performance Map 8.8 Compressor Instability - Stall and Surge 8.9 Multistage Compressors and their Operating Line 8.10 Multistage Compressor Stalling Pressure Rise and Stall Margin 8.11 Multistage Compressor Starting Problem 8.12 The Effect of Inlet Flow Condition on Compressor Performance 8.13 Isometric and Cutaway Views of Axial-Flow Compressor Hardware 8.14 Compressor Design Parameters and Principles 8.14.1 Blade Design - Blade Selection 8.14.2 Compressor Annulus Design 8.14.3 Compressor Stall Margin 8.15 Concepts in Compressor and Fan Noise Mitigation 8.16 Summary References Problems 9. Centrifugal Compressor Aerodynamics 9.1 Introduction 9.2 Centrifugal Compressors 9.3 Radial Diffuser 9.4 Inducer 9.5 Inlet Guide Vanes (IGVs) and Inducer-Less Impellers 9.6 Impeller Exit Flow and Blockage Effects 9.7 Efficiency and Performance 9.8 Summary References Problems 10. Aerothermodynamics of Gas Turbines 10.1 Introduction 10.2 Axial-Flow Turbines 10.2.1 Optimal Nozzle Exit Swirl Mach Number M theta 2 10.2.2 Turbine Blade Losses 10.2.2.1 Blade Profile Loss 10.2.2.2 Secondary Flow Losses 10.2.2.3 Annulus Losses 10.2.3 Optimum Solidity 10.2.4 Turbine Cooling 10.2.4.1 Convective Cooling 10.2.4.2 Impingement Cooling 10.2.4.3 Film Cooling 10.2.4.4 Transpiration Cooling 10.3 Turbine Performance Map 10.4 The Effect of Cooling on Turbine Efficiency 10.5 Turbine Blade Profile Design 10.5.1 Angles 10.5.2 Other Blade Geometrical Parameters 10.5.3 Throat Sizing 10.5.4 Throat Reynolds Number Reo 10.5.5 Turbine Blade Profile Design 10.5.6 Blade Vibration and Campbell Diagram 10.5.7 Turbine Blade and Disk Material Selection and Design Criteria 10.6 Stresses in Turbine Blades and Disks and Useful Life Estimation 10.7 Axial-Flow Turbine Design and Practices 10.8 Gas Turbine Design Summary 10.9 Advances in Turbine Material and Cooling 10.10 Summary References Problems 11. Aircraft Engine Component Matching and Off-Design Analysis 11.1 Introduction 11.2 Engine (Steady-State) Component Matching 11.2.1 Engine Corrected Parameters 11.2.2 Inlet-Compressor Matching 11.2.3 Compressor-Combustor Matching 11.2.4 Combustor-Turbine Matching 11.2.5 Compressor-Turbine Matching and Gas Generator Pumping Characteristics 11.2.5.1 Gas Generator Pumping Characteristics 11.2.6 Turbine-Afterburner (Variable-Geometry) Nozzle Matching 11.2.6.1 Fixed-Geometry Convergent Nozzle Matching 11.3 Engine Off-Design Analysis 11.3.1 Off-Design Analysis of a Turbojet Engine 11.3.2 Off-Design Analysis of an Afterburning Turbojet Engine 11.3.3 Off-Design Analysis of a Separate-Flow Turbofan (Two-Spool) Engine 11.4 Unchoked Nozzles and Other Off-Design Iteration Strategies 11.4.1 Unchoked Exhaust Nozzle 11.4.2 Unchoked Turbine Nozzle 11.4.3 Turbine Efficiency at Off-Design 11.4.4 Variable Gas Properties 11.5 Principles of Engine Performance Testing 11.5.1 Force of Inlet Bellmouth on Engine Thrust Stand 11.5.1.1 Bellmouth Instrumentation 11.5.1.2 The Effect of Fluid Viscosity 11.5.1.3 The Force of Inlet Bellmouth on Engine Thrust Stand 11.6 Summary References Problems 12. Chemical Rocket and Hypersonic Propulsion 12.1 Introduction 12.2 From Takeoff to Earth Orbit 12.3 Chemical Rockets 12.4 Chemical Rocket Applications 12.4.1 Launch Engines 12.4.2 Boost Engines 12.4.3 Space Maneuver Engines 12.4.4 Attitude Control and Orbital Correction Rockets 12.5 New Parameters in Rocket Propulsion 12.6 Thrust Coefficient, CF 12.7 Characteristic Velocity, c* 12.8 Flight Performance 12.9 Multistage Rockets 12.10 Propulsive and Overall Efficiencies 12.11 Chemical Rocket Combustion Chamber 12.11.1 Liquid Propellant Combustion Chambers 12.11.1.1 Some Design Guidelines for Injector Plates 12.11.1.2 Combustion Instabilities 12.11.2 Solid Propellant Combustion Chambers 12.12 Thrust Chamber Cooling 12.12.1 Liquid Propellant Thrust Chambers 12.12.2 Cooling of Solid Propellant Thrust Chambers 12.13 Combustor Volume and Shape 12.14 Rocket Nozzles 12.14.1 Multiphase Flow in Rocket Nozzles 12.14.2 Flow Expansion in Rocket Nozzles 12.14.3 Thrust Vectoring Nozzles 12.15 High-Speed Airbreathing Engines 12.15.1 Supersonic Combustion Ramjet 12.15.1.1 Inlet Analysis 12.15.1.2 Scramjet Combustor 12.15.1.3 Scramjet Nozzle 12.16 Rocket-Based Airbreathing Propulsion 12.17 Compact Fusion Reactor: The Path to Clean, Unlimited Energy 12.18 Summary References Problems