xxvi
Contents
12.5 Performance of Double-Flow Engines ............................................. 444
12.5.1 Unmixed Flows (Double-Jet Engine: Turbofan,
Turboprop) ......................................................................... 444
12.5.2 Mixed Flows (Bypass Engine) ........................................... 448
12.5.3 Intercooling and Recuperation ........................................... 450
12.6 Technological Aspects of the Turbofan Engine ................................ 451
12.6.1 Discs and Shafts ................................................................. 451
12.6.2 Vanes and Blades ................................................................ 451
12.6.3 Combustion Chamber ......................................................... 452
12.6.4 Mixer and Thrust Reverser ................................................. 454
12.7 Exercises .......................................................................................... 454
12.7.1 Single-Flow Jet Engine ...................................................... 454
12.7.2 Single-Flow Jet Engine with Post-Combustion ................. 455
12.7.3 Turbofan with Separate Flows ........................................... 456
12.7.4 Turbofan with Mixed Flows ............................................... 456
12.7.5 Optimisation of Turbine Inlet Temperature with a
Turbofan Engine ................................................................. 456
12.7.6 Helicopter Rotor ................................................................. 456
12.7.7 Ramjet ................................................................................ 457
References ................................................................................................. 457
13 Axial Compressors .................................................................................. 459
13.1 Mean Line Analysis .......................................................................... 459
13.1.1 Velocity Triangles ............................................................... 460
13.1.2 Fundamental Equations ...................................................... 461
13.1.3 Loss Representation ........................................................... 462
13.1.4 Loss Coefficients ................................................................ 465
13.1.5 Force Components ............................................................. 465
13.1.6 Diffusion Factor and Loss Correlations ............................. 466
13.1.7 Kinematic Parameters ........................................................ 470
13.1.8 Secondary Flow: Principle ................................................. 471
13.1.9 Radial Variation of Flow: Principle .................................... 473
13.1.10 Optimisation of a Stage .................................................... 474
13.1.11 Blade Shape ...................................................................... 476
13.1.12 Attainable Pressure Ratio ................................................. 478
13.2 Secondary Flow ................................................................................ 478
13.2.1 Definition of Secondary Flow ............................................ 478
13.2.2 Passage Vortex and Trailing Vortices ................................. 479
13.2.3 Corner Vortices ................................................................... 480
13.2.4 Horseshoe Vortex ............................................................... 480
13.2.5 Leakage Vortex and Scraping Vortex ................................. 480
13.2.6 Loss Assessment ................................................................. 481
13.3 Radial Flow Variation ....................................................................... 481
13.3.1 S 1 -S 2 Decomposition .......................................................... 481
13.3.2 Radial Equilibrium ............................................................. 482
13.3.3 Free Vortex Blades ............................................................. 483
Contents
12.5 Performance of Double-Flow Engines ............................................. 444
12.5.1 Unmixed Flows (Double-Jet Engine: Turbofan,
Turboprop) ......................................................................... 444
12.5.2 Mixed Flows (Bypass Engine) ........................................... 448
12.5.3 Intercooling and Recuperation ........................................... 450
12.6 Technological Aspects of the Turbofan Engine ................................ 451
12.6.1 Discs and Shafts ................................................................. 451
12.6.2 Vanes and Blades ................................................................ 451
12.6.3 Combustion Chamber ......................................................... 452
12.6.4 Mixer and Thrust Reverser ................................................. 454
12.7 Exercises .......................................................................................... 454
12.7.1 Single-Flow Jet Engine ...................................................... 454
12.7.2 Single-Flow Jet Engine with Post-Combustion ................. 455
12.7.3 Turbofan with Separate Flows ........................................... 456
12.7.4 Turbofan with Mixed Flows ............................................... 456
12.7.5 Optimisation of Turbine Inlet Temperature with a
Turbofan Engine ................................................................. 456
12.7.6 Helicopter Rotor ................................................................. 456
12.7.7 Ramjet ................................................................................ 457
References ................................................................................................. 457
13 Axial Compressors .................................................................................. 459
13.1 Mean Line Analysis .......................................................................... 459
13.1.1 Velocity Triangles ............................................................... 460
13.1.2 Fundamental Equations ...................................................... 461
13.1.3 Loss Representation ........................................................... 462
13.1.4 Loss Coefficients ................................................................ 465
13.1.5 Force Components ............................................................. 465
13.1.6 Diffusion Factor and Loss Correlations ............................. 466
13.1.7 Kinematic Parameters ........................................................ 470
13.1.8 Secondary Flow: Principle ................................................. 471
13.1.9 Radial Variation of Flow: Principle .................................... 473
13.1.10 Optimisation of a Stage .................................................... 474
13.1.11 Blade Shape ...................................................................... 476
13.1.12 Attainable Pressure Ratio ................................................. 478
13.2 Secondary Flow ................................................................................ 478
13.2.1 Definition of Secondary Flow ............................................ 478
13.2.2 Passage Vortex and Trailing Vortices ................................. 479
13.2.3 Corner Vortices ................................................................... 480
13.2.4 Horseshoe Vortex ............................................................... 480
13.2.5 Leakage Vortex and Scraping Vortex ................................. 480
13.2.6 Loss Assessment ................................................................. 481
13.3 Radial Flow Variation ....................................................................... 481
13.3.1 S 1 -S 2 Decomposition .......................................................... 481
13.3.2 Radial Equilibrium ............................................................. 482
13.3.3 Free Vortex Blades ............................................................. 483