Basic Concepts in Turbomachinery

This book is based on an introductory turbomachinery course at Durham University. This course was taught by Dr David Gregory-Smith and Professor Li He over a number of years and I am extremely grateful to them for providing a clear and lucid set of principles on which to base this work.

My current colleagues at Durham Dr Rob Dominy and Dr David Sims-Williams have also provided invaluable help (even if they didn’t realise it!) in preparing this work.

The book is designed to help students over some important “Threshold Concepts” in educational jargon. A threshold concept is an idea that is hard to grasp but once the idea is understood transforms the student understanding and is very hard to go back across. Within turbomachinery my view is that understanding the cascade view, velocity triangles and reaction form three threshold concepts, perhaps minor ones compared to the much bigger ideas such as "reactive power" or "opportunity cost" that are also proposed but this view has significantly influenced the production of this book.

I’d therefore like to acknowledge Professor Eric Meyer for introducing me to the idea of threshold concepts.

1. Introduction
   1. How this book will help you
   2. Things you should already know
   3. What is a Turbomachine?
   4. A Simple Turbine
   5. The Cascade View
   6. The Meridional View
   7. Assumptions used in the book
   8. Problems
2. Relative and Absolute Motion
   1. 1D Motion
   2. 2D Motion
   3. Velocity Triangles in Turbomachinery
   4. Velocity Components
   5. Problems
3. Simple Analysis of Wind Turbines
   1. Aerofoil Operation and Testing
   2. Wind Turbine Design
   3. Turbine Power Control
   4. Further Reading
   5. Problems
4. Different Turbomachines and Their Operation
   1. Axial Flow Machines
   2. Radial and Centrifugal Flow Machines
   3. Radial Impellers
   4. Centrifugal Impellers
   5. Hydraulic Turbines
   6. Common Design Choices
   7. The Turbomachine and System
   8. Problems
5. Application of The Equations of Fluid Motion
   1. Conservation of Mass
   2. Conservation of Momentum
   3. Conservation of Energy and Rothalpy
   4. Problems
6. Efficiency and Reaction
   1. Efficiency
   2. Reaction
   3. Reaction on the h - s Diagram
   4. Problems
7. Dimensionless Parameters for Turbomachinery
   1. Coefficients for Axial Machines
   2. Coefficients for Wind Turbines
   3. Coefficients for Hydraulic Machines
   4. Problems
8. Axial Flow Machines
   1. Reaction for Repeating Stage
   2. Loading and Efficiency Variation with Reaction
   3. Stage Efficiency
   4. Choice of Reaction for Turbines
   5. Compressor Design
   6. Multistage Steam Turbine Example
   7. Problems
9. Hydraulic Turbines
   1. Pelton Wheel
   2. Analysis Approach
   3. Francis Turbine
   4. Kaplan Turbine
   5. Problems
10. Analysis of Pumps
    1. Pump Diffuser Analysis
    2. Pump Losses
    3. Centrifugal Pump Example
    4. Net Positive Suction Head (NPSH)
    5. Application to Real Pumps
    6. Problems
11. Summary
12. Appendix A: Glossary of Turbomachinery Terms
13. Appendix B: Picture Credits