Aircraft Propulsion and Gas Turbine Engines

Part I Aero Engines and Gas Turbines
Chapter 1 History and Classifications of Aero Engines . . . 3
1.1 Prejet Engines—History 4
1.1.1 Early Activities in Egypt and China 4
1.1.2 Leonardo da Vinci . .. ... .5
1.1.3 Branca’s Stamping Mill . . . 5
1.1.4 Newton’s SteamWagon . . . 6
1.1.5 Barber’s Gas Turbine . .. 6
1.1.6 Miscellaneous Aero-Vehicles’Activities in the Eighteenth and Nineteenth
Centuries . .. . 7
1.1.7 TheWright Brothers . .. . 8
1.1.8 Significant Events up to 1940s . .. 10
1.1.8.1 Aero-Vehicle Activities . . 10
1.1.8.2 Reciprocating Engines . . . 12
1.2 Jet Engines . . . . 13
1.2.1 Jet Engine Inventors: Dr. Hans von Ohain and Sir FrankWhittle . . 13
1.2.1.1 Sir Frank Whittle (1907–1996) . .. 13
1.2.1.2 Dr. Hans von Ohain (1911–1998) . . . 14
1.2.2 Turbojet Engines. .. .. 15
1.2.3 Turboprop and Turboshaft Engines . 18
1.2.4 Turbofan Engines . .. .21
1.2.5 Propfan Engine 23
1.2.6 Pulsejet, Ramjet, and Scramjet Engines . .. . . 24
1.2.6.1 Pulsejet Engine . .. .. 24
1.2.6.2 Ramjet and Scramjet Engines . .. . 25
1.2.7 Industrial Gas Turbine Engines . .27
1.3 Classifications of Aerospace Engines . .. . . 28
1.4 Classification of Jet Engines. .. . . 29
1.4.1 Ramjet. .. .29
1.4.2 Pulsejet . .. . . . 30
1.4.3 Scramjet . .. . . 31
1.4.4 Turboramjet . . . . 31
1.4.5 Turborocket . . . . 32
1.5 Classification of Gas Turbine Engines . .. . 32
1.5.1 Turbojet Engines. .. .. 33
1.5.2 Turboprop . .. 34
1.5.3 Turboshaft. .. 35
1.5.4 Turbofan Engines . .. .37
1.5.5 Propfan Engines . .. .. 41
1.5.6 Advanced Ducted Fan . .42
1.6 Industrial Gas Turbines . 43
1.7 Non–Air-Breathing Engines . .. . . 44
1.8 Future of Aircraft and Power Plant Industries . .. .. 44
Closure . . . . 52
Problems . . 52
References 54
Chapter 2 Performance Parameters of Jet Engines . .. . . . 57
2.1 Introduction . . . 57
2.2 Thrust Force . . . 57
2.3 Factors Affecting Thrust 67
2.3.1 Jet Nozzle . .. 67
2.3.2 Air Speed . .. . 68
2.3.3 Mass Air Flow . 68
2.3.4 Altitude . .. . . . 68
2.3.5 Ram Effect . .69
2.4 Engine Performance Parameters . . . 70
2.4.1 Propulsive Efficiency . .. 70
2.4.2 Thermal Efficiency . .. . . 75
2.4.3 Propeller Efficiency. .. . . 76
2.4.4 Overall Efficiency . .. . . . 77
2.4.5 Takeoff Thrust . 80
2.4.6 Specific Fuel Consumption . .. . . . 81
2.4.7 Aircraft Range . 82
2.4.8 Range Factor . . . 85
2.4.9 Endurance Factor . .. .85
2.4.10 Specific Impulse . .. .. 87
Problems . . 91
References 94
Chapter 3 Pulsejet and Ramjet Engines . .. . . . 97
3.1 Introduction . . . 97
3.2 Pulsejet Engines. .. . . . 97
3.2.1 Introduction . . . . 97
3.2.2 Valved Pulsejet 98
3.2.3 Valveless Pulsejet. .. .102
3.2.4 Pulse Detonation Engine . . 103
3.3 Ramjet Engines . .. . . . 106
3.3.1 Ideal Ramjet . . . 107
3.3.2 Real Cycle . .110
3.4 Case Study. .129
3.5 Summary and Governing Equations for ShockWaves and Isentropic Flow . .. .. 141
3.5.1 Summary . .. . 141
3.5.2 Normal ShockWave Relations . .141
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3.5.3 Oblique ShockWave Relations . .142
3.5.4 Rayleigh-Flow Equations . .. .. 142
3.5.5 Isentropic Relation . .. . . 142
Problems . . 143
References 145
Chapter 4 Turbojet Engine . 147
4.1 Introduction . . . 147
4.2 Single Spool . . . 149
4.2.1 Examples of Engines . .. 149
4.2.2 Thermodynamic Analysis . .. .. 150
4.2.3 Ideal Case . .. 150
4.2.4 Actual Case . . . . 165
4.2.5 Comparison Between Operative and Inoperative Afterburner . .. . 175
4.3 Two-Spool Engine . .. 178
4.3.1 Nonafterburning Engine. . . 179
4.3.1.1 Example of Engines . .. 179
4.3.2.2 Thermodynamic Analysis 180
4.3.3 Afterburning Engine . .. . 183
4.3.3.1 Examples for Two-Spool Afterburning Turbojet Engines . .. .183
4.3.2.2 Thermodynamic Analysis 184
4.4 Statistical Analysis . .. 188
4.5 Thrust Augmentation . . . 189
4.5.1 Water Injection 189
4.5.2 Afterburning . . . 190
4.5.3 Pressure Loss in Afterburning Engine . .. .191
4.6 Supersonic Turbojet . .195
4.7 Optimization of the Turbojet Cycle . .. .198
Problems . . 209
References 213
Chapter 5 Turbofan Engines . .. .. 215
5.1 Introduction . . . 215
5.2 Forward Fan Unmixed Single-Spool Configuration. .216
5.3 Forward Fan Unmixed Two-Spool Engines . 221
5.3.1 The Fan and Low-Pressure Compressor on One Shaft. . . 221
5.3.2 Fan Driven by the LPT and the Compressor Driven by the HPT . . . 232
5.3.3 A Geared Fan Driven by the LPT and the Compressor Driven
by the HPT. .233
5.4 Forward Fan Unmixed Three-Spool Engine . 235
5.5 Forward Fan Mixed-Flow Engine . . 242
5.5.1 Mixed-Flow Two-Spool Engine . . . . 242
5.6 Mixed Turbofan with Afterburner . . 255
5.6.1 Introduction . . . . 255
5.6.2 Ideal Cycle . .256
5.6.3 Real Cycle . .258
5.7 AFT Fan . .. . 258
5.8 V/STOL. .. . . 261
5.8.1 Swiveling Nozzles . .. . . . 261
5.8.2 Switch-In Deflector System . .. . . . 266
5.9 Performance Analysis. . . 273
Summary. . 294
Problems . . 297
References 305
Chapter 6 Turboprop, Turboshaft, and Propfan Engines . . . 307
6.1 Introduction to Turboprop Engines . .. .307
6.2 Classification of Turboprop Engines . .. . . . 310
6.3 Thermodynamic Analysis of Turboprop Engines. .. . . 312
6.3.1 Single-Spool Turboprop . . . 312
6.3.2 Two-Spool Turboprop . .316
6.4 Analogy with Turbofan Engines. . . . 319
6.5 Equivalent Engine Power . .. .. 320
6.5.1 Static Condition320
6.5.2 Flight Operation . .. .. 320
6.6 Fuel Consumption . .. 320
6.7 Turboprop Installation . . 321
6.8 Performance Analysis. . . 329
6.9 Comparison Between Turbojet, Turbofan, and Turboprop Engines . .. .330
6.10 Turboshaft Engines . .333
6.11 Power Generated by Turboshaft Engines . . . . 334
6.11.1 Single-Spool Turboshaft . . 334
6.11.2 Double-Spool Turboshaft . .. .. 335
6.12 Examples for Turboshaft Engines . . 336
6.13 Propfan Engines. .. . . . 337
Summary of Turboprop Relations . .. . . . 340
Problems . . 340
References 344
Chapter 7 High-Speed Supersonic and Hypersonic Engines . .. . . . 345
7.1 Introduction . . . 345
7.2 Supersonic Aircraft and Programs . .. .. 345
7.2.1 Anglo-French Activities . . . 346
7.2.2 Russian Activities . .. .347
7.2.3 The U.S. Activities . .. . . . 347
7.3 Future of Commercial Supersonic Technology . .. .349
7.4 Technology Challenges of the Future Flight . 350
7.5 High-Speed Supersonic and Hypersonic Propulsion . . . . 350
7.5.1 Introduction . . . . 350
7.5.2 Hybrid Cycle Engine . .. 351
7.6 Turboramjet Engine . .352
7.7 Wraparound Turboramjet . .. .. 352
7.7.1 Operation as a Turbojet Engine . .352
7.7.2 Operation as a Ramjet Engine . .. 355
7.8 Over/Under Turboramjet . .. .. 356
7.8.1 Turbojet Mode . 358
7.8.2 Dual Mode . .358
7.8.3 Ramjet Mode . . 358
7.9 Turboramjet Performance . .. .358
7.9.1 Turbojet Mode . 358
7.9.2 Ramjet Mode . . 359
7.9.3 Dual Mode . .359
7.10 Case Study. .360
7.11 Examples for Turboramjet Engines . .. .365
7.12 Hypersonic Flight . .. . 367
7.12.1 History of Hypersonic Vehicles. .367
7.12.2 Hypersonic Commercial Transport . 369
7.12.3 Military Applications . .. 370
7.13 Scramjet Engines. .. . . 370
7.13.1 Introduction . . . . 370
7.13.2 Thermodynamics . .. .372
7.14 Intake of a Scramjet Engine . .. . . 372
7.15 Combustion Chamber. . . 373
7.16 Nozzle . .. . . . 376
7.17 Performance Parameters 376
Problems . . 380
References 383
Chapter 8 Industrial Gas Turbines . .385
8.1 Introduction . . . 385
8.2 Categories of Gas Turbines . .. . . . 386
8.3 Types of Industrial Gas Turbines . . . 387
8.4 Single-Shaft Engine. .388
8.4.1 Single Compressor and Turbine . . . . 389
8.4.1.1 Ideal Cycle. .. 389
8.4.1.2 Real Cycle . .. 392
8.4.2 Regeneration . . . 395
8.4.3 Reheat . .. .398
8.4.4 Intercooling . . . . 399
8.4.5 Combined Intercooling, Regeneration, and Reheat . .. 401
8.5 Double-Shaft Engine. . . . 406
8.5.1 Free Power Turbine . .. . . 406
8.5.2 Two Discrete Shafts (Spools) . .. . 408
8.6 Three Spool . . . 415
8.7 Combined Gas Turbine . 422
8.8 Marine Applications . . . . 423
8.8.1 Additional Components for Marine Applications . .. . . 424
8.8.2 Examples for Marine Gas Turbines . 426
8.9 Offshore Gas Turbines . . 427
8.10 Micro Gas Turbines (μ-Gas Turbines) . .. . 428
8.10.1 Microturbines versus Typical Gas Turbines . . . . 429
8.10.2 Design Challenges . .. . . . 429
8.10.3 Applications . . . . 430
Problems . . 431
References 433
Part II Component Design . .. .435
Chapter 9 Power Plant Installation and Intakes . 437
9.1 Introduction . . . 437
9.2 Power Plant Installation 437
9.3 Subsonic Aircraft. .. . . 437
9.3.1 Turbojet and Turbofan Engines . .438
9.3.1.1 Wing Installation . .. . . . 438
9.3.1.2 Fuselage Installation . .442
9.3.1.3 CombinedWing and Tail Installation (Three Engines) . . . 443
9.3.1.4 Combined Fuselage and Tail Installation . .444
9.3.2 Turboprop Installation . .444
9.4 Supersonic Aircraft . .446
9.4.1 Civil Transports 446
9.4.2 Military Aircrafts . .. .447
9.5 Air Intakes or Inlets . .448
9.6 Subsonic Intakes . .. . . 449
9.6.1 Inlet Performance . .. .451
9.6.2 Performance Parameters . . . 453
9.6.3 Turboprop Inlets . .. .. 457
9.7 Supersonic Intakes . .. 457
9.7.1 Review of Gas Dynamic Relations for Normal and Oblique Shocks . .. . . . 460
9.7.1.1 Normal ShockWaves . . . . 460
9.7.1.2 Oblique ShockWaves . . . . 461
9.7.2 External Compression Intake (Inlet) 462
9.7.3 Internal Compression Inlet (Intake) 467
9.7.4 Mixed Compression Intakes . .. . . 468
9.8 Matching Between Intake and Engine . .. . 470
9.9 Case Study. .472
Problems . . 475
References 479
Chapter 10 Combustion Systems. .. . . 481
10.1 Introduction . . . 481
10.2 Subsonic Combustion Chambers . . . 482
10.2.1 Tubular (or Multiple) Combustion Chambers . . 482
10.2.2 Tubo-Annular Combustion Chambers . .. .483
10.2.3 Annular Combustion Chambers. .484
10.3 Supersonic Combustion Chamber. . 485
10.4 Combustion Process . . . . 485
10.5 The Chemistry of Combustion . .487
10.6 Combustion Chamber Performance . .. .490
10.6.1 Pressure Losses 490
10.6.2 Combustion Efficiency . . . . 491
10.6.3 Combustion Stability . .. 491
10.6.4 Combustion Intensity . .. 492
10.7 Cooling . .. . . 493
10.8 Material . .. . . 495
10.9 Aircraft Fuels . . 496
10.10 Emissions and Pollutants . .. .. 497
10.10.1 Pollutant Formation . .. . 497
10.11 The Afterburner . .. . . . 498
10.12 Supersonic Combustion System. . . . 499
Problems . . 501
References 503
Chapter 11 Exhaust System . 505
11.1 Introduction . . . 505
11.2 Nozzle . .. . . . 507
11.2.1 Governing Equations . .. 508
11.2.1.1 Convergent–Divergent Nozzle . .. 508
11.2.1.2 Convergent Nozzle . .. . 511
11.2.2 Variable Geometry Nozzles . .. . . . 512
11.2.3 Afterburning Nozzles . .. 514
11.3 Calculation of the Two-Dimensional Supersonic Nozzle . .. . . . 517
11.3.1 Convergent Nozzle . .. . . 518
11.3.2 Divergent Nozzle . .. .522
11.3.2.1 Analytical Determination of the Contour of a Nozzle . . . . 525
11.3.2.2 Design Procedure for a Minimum Length Divergent Nozzle . .. 527
11.3.2.3 Procedure of Drawing the ExpansionWaves Inside the Nozzle . . . 528
11.4 Thrust Reversal . .. . . . 529
11.4.1 Classification of Thrust Reverser Systems . .531
11.4.2 Calculation of Ground Roll Distance . .. .. 536
11.5 Thrust Vectoring . .. . . 537
11.5.1 Governing Equations . .. 540
11.6 Noise. .. .. 541
11.6.1 Introduction . . . . 541
11.6.2 Acoustics Model Theory . . 543
11.6.3 Methods Used to Decrease the Jet Noise . .. . 544
Problems . . 547
References 548
Chapter 12 Centrifugal Compressors . . . 551
12.1 Introduction . . . 551
12.2 Layout of Compressor . . 553
12.2.1 Impeller . .. . . 553
12.2.2 Diffuser . .. . . 554
12.2.3 Scroll or Manifold . .. . . . 556
12.3 Classification of Centrifugal Compressors . . 556
12.4 Governing Equations . . . 559
12.4.1 The Continuity Equation . . 562
12.4.2 The Momentum Equation or Euler’s Equation for Turbomachinery . .. .562
12.4.3 The Energy Equation or the First Law of Thermodynamics . .. . . . 563
12.4.4 Slip Factor σ . . . 567
12.4.5 Prewhirl . .. . . 570
12.4.6 Types of Impeller . .. .581
12.5 Diffuser . .. . . 589
12.5.1 Vaneless Diffuser . .. .590
12.5.2 Vaned Diffuser. 592
12.6 Discharge Systems . .. 598
12.7 Characteristic Performance of a Centrifugal Compressor . .. . . 598
12.8 Erosion . .. . . 602
12.8.1 Introduction . . . . 602
12.8.2 Theoretical Estimation of Erosion . . 605
Problems . . 609
References 616
Chapter 13 Axial-Flow Compressors and Fans. . . 619
13.1 Introduction . . . 619
13.2 Comparison Between Axial and Centrifugal Compressors . .. . 621
13.2.1 Advantages of the Axial-Flow Compressor Over
the Centrifugal Compressor . .. . . . 621
13.2.2 Advantages of Centrifugal-Flow Compressor Over the Axial-Flow
Compressor . . . . 622
13.2.3 Main Points for Comparison Between Centrifugal and Axial Compressors . . 623
13.3 Mean Flow (Two-Dimensional Approach) . . 623
13.3.1 Types of Velocity Triangles . .. . . . 625
13.3.2 Variation of Enthalpy Velocity and Pressure of an
Axial Compressor . .. .627
13.4 Basic Design Parameters . .. .. 635
13.4.1 Centrifugal Stress . .. .635
13.4.2 Tip Mach Number . .. . . . 637
13.4.3 Fluid Deflection638
13.5 Design Parameters . .. 639
13.5.1 Degree of Reaction . .. . . 640
13.6 Three-Dimensional Flow . .. .. 642
13.6.1 Axisymmetric Flow. .. . . 643
13.6.2 Simplified Radial Equilibrium Equation . .. . 644
13.6.3 Free Vortex Method . .. . 646
13.6.4 General Design Procedure . .. .651
13.7 Complete Design Process for Compressor. . . 659
13.8 Rotational Speed (RPM) and Annulus Dimensions . .659
13.9 Determine Number of Stages (Assuming Stage Efficiency) . .. 662
13.10 Calculation of Air Angles for Each Stage at the Mean Section . . . 663
13.10.1 First Stage . .. 663
13.10.2 Stages from (2) to (n−1) . .. .. 664
13.10.3 Last Stage . .. 665
13.11 Variation of Air Angles from Root to Tip Based on the Type of Blading (Free
Vortex-Exponential-First Power) . . . 666
13.12 Blade Design . . 667
13.12.1 Cascade Measurements. . . . 667
13.12.2 Choosing the Type of Airfoil . .. . . 672
13.12.3 Stage Performance . .. . . . 672
13.12.3.1 Blade Efficiency and Stage Efficiency . .. . . 677
13.13 Compressibility Effects . 679
13.14 Performance . . . 687
13.14.1 Single Stage . . . . 687
13.14.2 Multistage Compressor . . . . 689
13.14.3 Compressor Map . .. .690
13.14.4 Stall and Surge . 691
13.14.5 Surge Control Methods. . . . 694
13.14.5.1 Multispool Compressor . . 694
13.14.5.2 Variable Vanes . . 694
13.14.5.3 Air Bleed. .. . . 695
13.15 Case Study. .701
13.15.1 Mean Section Data . .. . . 701
13.15.2 Variations from Hub to Tip . .. . . . 701
13.15.3 Details of Flow in Stage Number 2 . 703
13.15.4 Number of Blades and Stresses of the Seven Stages. .704
13.15.5 Compressor Layout . .. . . 705
13.16 Erosion . .. . . 708
13.17 Fouling . .. . . 712
Problems . . 714
References 725
Chapter 14 Axial Turbines. . . 727
14.1 Introduction . . . 727
14.2 Comparison Between Axial Flow Compressors and Turbines . . . . 729
14.3 Aerodynamics and Thermodynamics for a Two-Dimensional Flow . .. . . . 730
14.3.1 Velocity Triangles . .. . . . 730
14.3.2 Euler’s Equation . .. .. 732
14.3.3 Efficiency, Losses, and Pressure Ratio . .. . . . 734
14.3.4 Nondimensional Quantities . .. . . . 738
14.3.5 Several Remarks . .. .. 746
14.4 Three Dimensional . .. 752
14.4.1 Free Vortex Design . .. . . 753
14.4.2 Constant Nozzle Angle Design (α2) 753
14.4.3 General Case . . . 756
14.4.4 Constant Specific Mass Flow Stage 757
14.5 Preliminary Design . .772
14.5.1 Main Design Steps. .. . . . 772
14.5.2 Aerodynamic Design . .. 772
14.5.3 Blade Profile Selection . . . . 774
14.5.4 Mechanical and Structural Designs . 775
14.5.4.1 Centrifugal Stresses . .. 775
14.5.4.2 Centrifugal Stresses on Blades . .. 776
14.5.4.3 Centrifugal Stresses on Discs . .. . . 777
14.5.4.4 Gas Bending Stress . .. . 779
14.5.4.5 Centrifugal Bending Stress . .. .781
14.5.4.6 Thermal Stress . . 781
14.5.5 Turbine Cooling . .. .. 782
14.5.5.1 Turbine Cooling Techniques . .. . . . 782
14.5.5.2 Mathematical Modeling. . 784
14.5.6 Losses and Efficiency . .790
14.5.6.1 Profile Loss (Yp) . .. . . . 790
14.5.6.2 Annulus Loss . . . 791
14.5.6.3 Secondary Flow Loss . . . . 791
14.5.6.4 Tip Clearance Loss (Yk) . 792
14.6 Turbine Map. . . 793
14.7 Case Study. .797
14.7.1 Design Point . . . 797
Summary. . 804
Problems . . 805
References 811
Chapter 15 Radial Inflow Turbines . .813
15.1 Introduction . . . 813
15.2 Thermodynamics. .. . . 814
15.3 Dimensionless Parameters . .. .818
15.4 Preliminary Design . .819
15.5 Breakdown of Losses . . . 822
15.6 Design for Optimum Efficiency . . . . 825
15.7 Cooling . .. . . 829
Problems . . 830
References 832
Chapter 16 Module Matching . .. .. 833
16.1 Introduction . . . 833
16.2 Off-Design Operation of a Single-Shaft Gas Turbine Driving a Load . .. . 833
16.2.1 Matching Procedure . .. . 834
16.2.2 Different Loads 839
16.3 Off Design of Free Turbine Engine . .. .839
16.3.1 Gas Generator. . 840
16.3.2 Free Power Turbine . .. . . 841
16.4 Off Design of Turbojet Engine . .846
Problems . . 851
References 853
Appendix A Glossary
Appendix B Data base for turbofan engines
Appendix C Gas Turbines