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Contents
9.3 Pelton Turbines: Impulse Turbines ................................................... 324
9.3.1 Performance Characteristics ................................................. 324
9.3.2 Specific Speed ...................................................................... 326
9.3.3 Determination of the Main Dimensions ............................... 328
9.3.4 Flow Rate Control and Over-Speed Protection .................... 328
9.4 Francis and Kaplan Turbines: Reaction Turbines ............................ 329
9.4.1 Shape of the Velocity Triangles: Kinematic Parameters ...... 329
9.4.2 Optimisation of the Velocity Triangles ................................ 330
9.4.3 Degree of Reaction and Speed Ratio ................................... 331
9.4.4 Velocity Triangles with Varying Degree of Reaction ........... 332
9.4.5 Specific Speed and Meridional Shape of Francis Turbines . 333
9.4.6 Flow Rate Control with Reaction Turbines .......................... 335
9.4.7 Examples (Figs. 9.16, 9.17) ................................................. 337
9.5 Bulb and Tube Turbines ................................................................... 338
9.6 Reversible Pump-Turbines ............................................................... 340
9.7 Exercises .......................................................................................... 342
References ................................................................................................. 345
10 Wind Turbines ......................................................................................... 347
10.1 Wind Energy ................................................................................... 347
10.2 Types of Wind Energy Conversion Systems .................................. 348
10.2.1 Drag Machines ................................................................. 348
10.2.2 High-Speed Horizontal-Axis Turbines ............................. 349
10.2.3 Technical Aspects of Horizontal-Axis Wind
Turbines for Electricity Generation .................................. 351
10.2.4 Low-Speed Horizontal-Axis Wind Turbines .................... 355
10.2.5 Vertical-Axis Wind Turbines ............................................ 356
10.3 Wind Turbine Performance Analysis ............................................. 358
10.3.1 Momentum Analysis (Single Streamtube Analysis) ........ 358
10.3.2 Multiple Streamtube Analysis .......................................... 361
10.3.3 Blade Element Analysis ................................................... 363
10.4 Adaptation to a Wind Regime ........................................................ 365
References ................................................................................................. 368
11 Power Gas Turbines .............................................................................. 369
11.1 General Concept and Components ................................................. 369
11.1.1 Definition of a Gas Turbine .............................................. 369
11.1.2 Comparison with Other Thermal Engines ........................ 371
11.1.3 Example of a Power Gas Turbine ..................................... 372
11.1.4 Compressor Part ............................................................... 374
11.1.5 Turbine Part ...................................................................... 377
11.1.6 Combustion Chamber ....................................................... 381
11.2 Thermodynamic Modelling ............................................................ 384
11.2.1 Isentropic Efficiency with Adiabatic Compression
or Expansion ..................................................................... 384
11.2.2 Reheat Effect .................................................................... 387