A turbine is a machine, system or device which uses kinetic energy from a moving fluid to produce mechanical energy for various purposes.
This article discusses the concept of the turbine from the following perspectives;
Turbine Meaning: 7 Different Definitions of a Turbine
A turbine is a device which harnesses hydrodynamic energy to produce mechanical energy.
Hydrodynamic energy describes energy from moving fluids, which is essentially kinetic energy. There are different forms in which this energy may occur, and some of these are highlighted in the following definition;
A turbine is a system which converts kinetic energy from flowing water, air, steam, and mobile fluids to mechanical energy .
To provide more clarity, it is important to highlight the basic principle by which the conversion of kinetic energy to mechanical energy in a turbine is achieved, as done below;
A turbine is a machine comprised of rotary or translational components like rotors, wheels and shafts, that are set into motion by an energetic stream of fluid such as steam, water and combustion gases, thereby producing mechanical energy.
Another important factor to consider is the use(s) of mechanical energy produced by the turbine;
A turbine is a device which harnesses and converts kinetic energy from a fluid to produce mechanical energy which can be used to support mechanical systems such as an electric generator that is used to generate electricity.
Turbines can be defined based on physical principles and quantities, as follows;
A turbine is a machine made up of mechanical components that are driven by momentum, angular velocity, kinetic energy and pressure from mobile fluids, to produce mechanical energy.
Based on the source of kinetic energy, a turbine can be integrated into renewable or non-renewable energy systems, as described in the following definition;
Lastly, a turbine can be defined in terms of the various types, configurations and methods of doing work;
A turbine is a mechanical device that uses kinetic energy from a moving liquid, or a stream of pressurized gas, to mobilize a system of rotors, wheels, drums or translational components, thereby producing mechanical energy that can be used to do work.
Working Principle of a Turbine
The working principle of a turbine is kineto-mechanical conversion.
Turbines typically function based on a three-step process, which includes kinetic energy input, kineto-mechanical conversion, and mechanical energy output. These steps are discussed below;
1). Kinetic Energy Input (Step 1 in Turbine Operational Process)
The first step in the operational process for a turbine involves deriving kinetic energy from a source.
This primary source of energy may vary. Examples include fossil fuels and their derivatives like coal, diesel and natural gas, and renewable energy sources.
Fossil fuels like coal and natural gas are burnt to produce heat energy, which is converted to kinetic energy through a hydrothermal process, whereby a fluid is heated so that its molecules become excited and pressurized .
The locomotion of these excited molecules is what produces kinetic energy. This two-stage conversion of heat to kinetic energy in the first step, occurs in all turbines that rely on fuels, which includes gas turbines, diesel-driven turbines, and bioenergy turbines.
In terms of renewable primary-energy sources, biomass can serve as a fuel for turbine-based electricity generation systems. In such systems, heat energy can be derived from biomass through direct heating, in the form of incineration, or through the combustion of biofuels produced when biomass is converted by anaerobic digestion or pyrolysis, among other methods.
Other types of renewable energy like solar, wind and geothermal, can provide energy to a turbine system, either directly in the kinetic form, or as heat which is subsequently converted to kinetic energy.
In the case of wind, wind turbines directly harness kinetic energy from moving streams of air (wind). Geothermal and solar produce heat, which is then used to mobilize a fluid and produce kinetic energy that is needed by the turbine.
2). Kineto-Mechanical Conversion (Step 2 in Turbine Operational Process)
After kinetic energy is received by the turbine, it converts this kinetic energy to mechanical energy.
In order to achieve this, the mobile fluid must come in contact with a mechanical (moveable) part of the turbine system. This part is usually called a rotor, which is an essential component of electric generators and motors.
The rotor in many turbines, occurs as a metallic, rotary component which is equipped with protruding part(s) like blades that provide a surface of contact with the fluid.
In order to move freely, the rotor is attached to a shaft which is inserted into a bearing-supported groove that reduces the effect of friction on the system, thereby mitigating energy loss, as well as wear and tear.
3). Mechanical Energy Output (Step 3 in Turbine Operational Process)
This is the final step in the operational process of a turbine.
When kineto-mechanical conversion occurs, kinetic energy input is converted to mechanical energy output by the turbine.
The mechanical energy which has been produced is transmitted by the rotor to other components that require it.
Alternatively, it can be used to generate electricity through an electromagnetic process, where the rotation of a conductor within a magnetic field, causes electrons to flow, resulting in electricity. This process is based on the principle of electromagnetism, described in Faraday’s Law .
Turbine Components and their Functions
The three main parts of a turbine are the energy inlet, conversion system and energy outlet.
Energy inlet receives energy from the primary source, the conversion system transforms this energy to mechanical (or any other usable form), and the energy outlet transmits the converted energy to its point of use.
These three main parts and their functions are each elaborated briefly as follows;
1). Energy Inlet of A Turbine
The energy inlet of a turbine is the part through which the primary source of energy is introduced into the system.
This is usually a fuel tank, reactor, mechanical apparatus or thermal collector.
The fuel tank is used where the primary energy source is a fuel which occurs in fluid form. In such cases, the turbine itself is simply part of a larger electricity generation system, which includes an engine for fuel combustion, and a tank for fuel collection.
Fuel tanks occur in steam, diesel, gas and biomass turbine generators.
A mechanical apparatus acts as the energy inlet in turbine where the primary energy occurs in kinetic form. Examples include wind turbines, which receive kinetic energy directly from wind.
The mechanical apparatus is usually designed to act as an energy capture system. This is exemplified by the blades of the wind turbine.
Reactors serve as energy inlet in turbine systems that use non-fluid fuels like biomass and municipal solid waste. These reactors provide a medium to derive heat energy from these non-fluid fuels, by direct combustion or pyrolysis.
Thermal collectors are found in systems that receive their primary energy in the form of heat. These include geothermal and solar systems.
2). Conversion System of A Turbine
The conversion system of a turbine includes all parts which carry out or support the transformation of energy in the turbine.
There are various possible forms of conversion in a turbine. Energy may be converted from chemical to heat, heat to kinetic, and kinetic to mechanical.
The design of such conversion systems is usually carried out with the aim to achieve energy conservation and efficiency through the minimization of frictional resistance. Conversion systems may comprise of heat exchangers, and kineto-mechanical components like rotors.
In turbine electric generators, the conversion system may include a gas chamber, which provides high-pressure hydrodynamic force that is used to produce mechanical energy.
3). Energy Outlet of A Turbine
The energy outlet includes all parts of a turbine that help to transmit mechanical energy which has been produced by the turbine, through kineto-mechanical conversion.
In many turbines, this is the rotor or shaft, which also helps to convert kinetic energy to mechanical energy. The energy output can be used to generate electricity through electromagnetic induction, or to control loads.
The magnitude of energy output from a turbine depends on factors like the size of rotor blades and the amount of frictional resistance.
Turbine Engine and Generator: Description and Comparison
A turbine is a kineto-mechanical device or machine which converts kinetic energy to mechanical energy.
A turbine engine is an engine which depends on heat from the combustion of a fuel to mobilize a fluid and produce mechanical energy by moving a turbine.
Turbine engines may be described as internal combustion engines, because they mostly operate as a closed system which receives primary energy from any of various types of fuel.
A turbine generator is an electric generator which depends on a turbine to provide the mechanical energy or motion required to generate electricity through electromagnetic induction.
Turbine generators may alternatively be referred to as turbine-driven generators  because they basically depend on the turbine to carry out the most crucial task of electricity generation.
A turbine differs from a turbine engine and a turbine generator because it is a component, whereas the engine and generator are systems. These systems include a turbine among other components which make them up, and they depend on the kineto-mechanical role of the turbine to operate effectively.
A turbine is a device that can be used to generate electricity, based on the conversion of kinetic energy from an energy source, to mechanical energy which is given as output.
The working principle of a turbine kineto-mechanical conversion, and the three steps in the operation of a turbine are;
- Kinetic Energy Input
- Kineto-Mechanical Conversion
- Mechanical Energy Output
While turbines may come in various forms with various designs, their components can be broadly categorized into three.
The three main parts of a turbine are;
- Energy Inlet
- Conversion System
- Energy Outlet
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