Page 9 - Fluid Mechanics and Thermodynamics of Turbomachinery

viii Contents
Performance of centrifugal compressors 219
The diffuser system 227
Choking in a compressor stage 230
References 232
Problems 233

8. Radial Flow Gas Turbines 236

Introduction 236
Types of inward flow radial turbine 237
Thermodynamics of the 90 deg IFR turbine 239
Basic design of the rotor 241
Nominal design point efficiency 242
Mach number relations 246
Loss coefficients in 90 deg IFR turbines 247
Optimum efficiency considerations 248
Criterion for minimum number of blades 253
Design considerations for rotor exit 256
Incidence losses 260
Significance and application of specific speed 263
Optimum design selection of 90 deg IFR turbines 266
Clearance and windage losses 269
Pressure ratio limits of the 90 deg IFR turbine 269
Cooled 90 deg IFR turbines 271
References 272
Problems 273

9. Hydraulic Turbines 277
Introduction 277
Hydraulic turbines 278
The Pelton turbine 281
Reaction turbines 290
The Francis turbine 290
The Kaplan turbine 296
Effect of size on turbomachine efficiency 299
Cavitation 301
References 305
Problems 306

Bibliography 309

Appendix 1. Conversion of British and US Units to SI Units 310

Appendix 2. Answers to Problems 311

Index 315