Types Of Turbines - Impulse and Reaction, Axial and Radial, Ceramic

Types of turbine

1. Impulse and Reaction turbine

The basic classification of a turbine is the impulse and reaction.
Impulse turbines: Fixed blade (nozzle) converts pressure energy into kinetic energy. Consequently, the moving blade only receives kinetic energy. The pressure at the inlet and outlet of the moving blades is same and equal to atmospheric.  Examples: Pelton turbines, Banki turbine
Reaction turbines: Both pressure and kinetic energy available at moving blades. The inlet pressure is much higher than the fluid pressure at the outlet. Examples: Francis turbine, Kaplan turbine, Propeller turbine.
Read: Difference between impulse and reaction turbine

2. Axial and Radial Turbine

Depending on the direction of flow of fluid in the impeller of the turbine.
Axial turbine: Direction of flow in the impeller is parallel to the axis. Examples: Propeller Turbine, Kaplan turbine.
Radial turbine: The direction of flow is perpendicular to the impeller shaft. Examples: Francis turbine (inward- radial turbine), Fourneyron turbine (outward-radial turbine)
Mixed: the direction flow has an axial, radial components. Example: Modern Francis turbine

Pelton,Francis turbine 

3. According to Working fluid

Steam turbines: They work by converting the thermal energy stored in the steam into mechanical energy. Steam turbines are used for electricity generation in thermal power stations. The steam is channelled through a turbine so multistage rotating blades, which drive the electric generator. Such plants use coal, natural gas, fossil fuel or nuclear fuel.
Gas turbines (Turbine engine):  Type of IC engine. Such engines usually have an inlet, compressor, combustion chamber, nozzle and fan. Example: Turbojet
Hydraulic turbines: Working fluid is water. Examples: Pelton wheel, Francis turbine, Kaplan Turbine.
Wind turbine: Wind turbines convert the kinetic energy of wind into mechanical energy, which can be directly used in machinery for purposes such as pumping water or grinding grains. In this case, the machine is known as the windmill. In other cases, the mechanical energy can be converted into electricity, it is called wind power unit (WPU), wind energy converter (WEC) or wind turbine.
Mercury vapour turbines:  used to improve the efficiency of fossil fuelled power plants. Not widely adopted because capital cost and toxicity.

Kaplan, Turbojet

Ceramic turbine: conventional high-pressure turbine blades are made from nickel alloys and often intricate with the use of internal air cooling ducts to prevent overheating the metal. In recent years, experimental ceramic blades have been manufactured and tested in gas turbines, with the aim of increasing rotor inlet temperatures and possibly eliminate the air cooling system. Ceramic blades are more fragile than their metallic counterparts and this lead to an increased risk of catastrophic blade failure.

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