1
Chapter 1
Working Principles
© Springer Science+Business Media Dordrecht 2015
E. Dick, Fundamentals of Turbomachines, Fluid Mechanics and Its Applications 109,
DOI 10.1007/978-94-017-9627-9_1
Abstract In this chapter, we study the working principles of turbomachines with
a number of characteristic examples. Further, we derive the basic laws for energy
exchange between a shaft and a fluid and the laws describing energy changes on the
fluid side. We also analyse the role of the energy exchanging forces and introduce
definitions of efficiency.
1.1 Definition of a Turbomachine
A turbomachine is a machine that exchanges energy between the continuous flow
of a fluid and a continuously rotating blade system, with the energy exchange based
on flow-generated forces. Energy may be transferred from the flow to the rotating
machine components or vice versa. In the first case, energy extracted from the flow
is used to drive a rotating component, generally called a rotor (bladed drum, bladed
wheel or collection of bladed wheels), driving on its turn a useful external load. The
machine may then be called shaft power delivering, or for short, power delivering,
but typically it is termed a turbine, irrespective of the fluid.
Possible fluids are:
• water: water turbine or hydraulic turbine
• steam (vapour): steam turbine
• air in natural wind: wind turbine
• gas produced by combustion of a fuel in pressurised air: gas turbine
• other fluid, as refrigerant in a cooling cycle: expansion turbine.
When energy is supplied to the fluid by the rotor, the machine has to be driven by an
external motor. It may be called shaft power receiving, or shortly, power receiving.
Specific names are used, depending on the fluid and the energy component that is
mainly increased. Energy exchanged between a rotor and a fluid is mechanical energy in a technical sense (this will be explained in Sect. 1.4.4). Mechanical energy
essentially can only take two forms within the machine itself: velocity-associated
energy (kinetic energy) and pressure-associated energy (pressure potential energy
in case of a constant density fluid).
Chapter 1
Working Principles
© Springer Science+Business Media Dordrecht 2015
E. Dick, Fundamentals of Turbomachines, Fluid Mechanics and Its Applications 109,
DOI 10.1007/978-94-017-9627-9_1
Abstract In this chapter, we study the working principles of turbomachines with
a number of characteristic examples. Further, we derive the basic laws for energy
exchange between a shaft and a fluid and the laws describing energy changes on the
fluid side. We also analyse the role of the energy exchanging forces and introduce
definitions of efficiency.
1.1 Definition of a Turbomachine
A turbomachine is a machine that exchanges energy between the continuous flow
of a fluid and a continuously rotating blade system, with the energy exchange based
on flow-generated forces. Energy may be transferred from the flow to the rotating
machine components or vice versa. In the first case, energy extracted from the flow
is used to drive a rotating component, generally called a rotor (bladed drum, bladed
wheel or collection of bladed wheels), driving on its turn a useful external load. The
machine may then be called shaft power delivering, or for short, power delivering,
but typically it is termed a turbine, irrespective of the fluid.
Possible fluids are:
• water: water turbine or hydraulic turbine
• steam (vapour): steam turbine
• air in natural wind: wind turbine
• gas produced by combustion of a fuel in pressurised air: gas turbine
• other fluid, as refrigerant in a cooling cycle: expansion turbine.
When energy is supplied to the fluid by the rotor, the machine has to be driven by an
external motor. It may be called shaft power receiving, or shortly, power receiving.
Specific names are used, depending on the fluid and the energy component that is
mainly increased. Energy exchanged between a rotor and a fluid is mechanical energy in a technical sense (this will be explained in Sect. 1.4.4). Mechanical energy
essentially can only take two forms within the machine itself: velocity-associated
energy (kinetic energy) and pressure-associated energy (pressure potential energy
in case of a constant density fluid).