Turbine & it's types

Turbine:

A turbine is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating electrical power when combined with a generator or producing thrust, as in the case of jet engines.A turbine is a turbomachine with at least one moving part called a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades so that they move and impart rotational energy to the rotor. Early turbine examples are windmills and waterwheels.

Gas, steam, and water turbines have a casing around the blades that contains and controls the working fluid. Credit for the invention of the steam turbine is given both to British engineer Sir Charles Parsons (1854–1931) for the invention of the reaction turbine and to Swedish engineer Gustaf de Laval (1845–1913) for the invention of the impulse turbine. Modern steam turbines frequently employ both reaction and impulse in the same unit, typically varying the degree of reaction and impulse from the blade root to its periphery.

Types of turbine:

Steam turbines:

Steam turbines are used for the generation of electricity in thermal power plants, such as plants using coal, fuel oil or nuclear fuel. They were once used to directly drive mechanical devices such as ships' propellers but most such applications now use reduction gears or an intermediate electrical step, where the turbine is used to generate electricity, which then powers an electric motor connected to the mechanical load. 

Gas Turbines:

Gas turbines are sometimes referred to as turbine engines. Such engines usually feature an inlet, fan, compressor, combustor, and nozzle (possibly other assemblies) in addition to one or more turbines

Transonic Turbine:

The gas flow in most turbines employed in gas turbine engines remains subsonic throughout the expansion process. In a transonic turbine, the gas flow becomes supersonic as it exits the nozzle guide vanes, although the downstream velocities normally become subsonic. Transonic turbines operate at a higher pressure ratio than normal but are usually less efficient and uncommon.

Contra-rotating Turbine:

Contra-rotating turbines. With axial turbines, some efficiency advantage can be obtained if a downstream turbine rotates in the opposite direction to an upstream unit. However, the complication can be counter-productive. A contra-rotating steam turbine, usually known as the Ljungström turbine, was originally invented by Swedish Engineer Fredrik turbines. 

Statorless turbine:

Multi-stage turbines have a set of static (meaning stationary) inlet guide vanes that direct the gas flow onto the rotating rotor blades. In a stator-less turbine, the gas flow exiting an upstream rotor impinges onto a downstream rotor without an intermediate set of stator vanes (that rearrange the pressure/velocity energy levels of the flow) being encountered.

Ceramic turbine:

Conventional high-pressure turbine blades (and vanes) are made from nickel-based alloys and often utilize intricate internal air-cooling passages to prevent the metal from overheating. In recent years, experimental ceramic blades have been manufactured and tested in gas turbines, with a view to increasing rotor inlet temperatures and/or, possibly, eliminating air cooling. Ceramic blades are more brittle than their metallic counterparts and carry a greater risk of catastrophic blade failure. This has tended to limit their use in jet engines and gas turbines to the stator (stationary) blades.

.

Shroudless turbine:

Shroudless turbine. Modern practice is, wherever possible, to eliminate the rotor shrouding, thus reducing the centrifugal load on the blade and the cooling requirements.

Bladeless turbine:

Bladeless turbine uses the boundary layer effect and not a fluid impinging upon the blades as in a conventional turbine.

Water turbines:

1. Pelton turbine, a type of impulse water turbine.
2. Francis turbine, a type of widely used water turbine.
3. Kaplan turbine, a variation of the Francis Turbine.
4. Turgo turbine, a modified form of the Pelton wheel.
5. Cross-flow turbine, also known as Banki-Michell turbine, or Ossberger turbine.

Uses of turbines:

• Almost all electrical power on Earth is generated with a turbine of some type. Very high-efficiency steam turbines harness around 40% of the thermal energy, with the rest exhausted as waste heat.
• Most jet engines rely on turbines to supply mechanical work from their working fluid and fuel as do all nuclear ships and power plants.
• Turboexpanders are widely used as sources of refrigeration in industrial processes.

these are the main types of turbines.....

source-Wikipedia