What is Turbine and its types

A turbine  is a rotating mechanical device that extracts energy from a fluid flow and converts it For useful work.When combined with a generator, the work produced can be used to generate electricity.A turbomachine is a turbomachine that has at least one moving part called a rotor assembly, which is a shaft or drum to which blades are attached.The flowing fluid acts on the blades, causing them to move and transferring rotational energy to the rotor.Early examples of turbines are windmills and watermills.Gas, steam and water turbines have a casing around the blades to contain and contain the working fluid.The invention of the steam turbine is credited both to the Anglo-Irish engineer Sir Charles Parsons (1854-1931) for his reaction steam turbine and to the Swedish engineer Gustaf de Laval (1845-1913) invented the impulse steam turbine.Modern steam turbines often use both reaction and impulse in the same unit, usually varying the degree of reaction and impulse from the blade root to its perimeter.Hero of Alexandria demonstrates turbine principles in the Wind Column in the first century AD and Vitruvius mentions them around 70 BC.The word "turbines" was coined in 1822 by French mining engineer Claude Burdin from the Greek τύρβη, tyrbē meaning "vortex" or "rotation", in a memorandum "Des turbines hydrauliques ou machines rotatoires à grande vitesse" In, he said submitted to the Royal Academy of Paris.Benoit Fourneyron, former student of Claude Burdin, builds the first practical water turbine.

Types 

Steam turbines are used to drive generators in thermal power plants using coal, fuel oil or nuclear fuel.They were once used to directly drive mechanical equipment, such as a ship's propeller (e.g.Turbinia, the first turbine-powered steamship),but now most such applications use reduction gears or intermediate electric steps where the turbine is Used to generate electricity, which      then powers an electric motor connected to a mechanical load.Turbo-electric marine machinery was particularly popular before and during World War II, largely due to the lack of adequate gear-cutting equipment in American and British shipyards.Aircraft gas turbine engines are sometimes called turbine engines to distinguish them from piston engines.Transonic turbines.The gas flow in most turbines used in gas turbine engines remains subsonic throughout the expansion process.In a transonic turbine, the airflow becomes supersonic as it exits the nozzle vanes, although downstream velocities typically become subsonic.Transonic turbines operate at higher pressure ratios than normal, but are generally less efficient and uncommon.Counter-rotating turbines.With axial turbines, some efficiency advantages can be gained if the downstream turbine rotates in the opposite direction to the upstream unit.However, complications can backfire.The contra-rotating steam turbine, commonly known as the Ljungström turbine, was first invented in Stockholm by Swedish engineer Fredrik Ljungström (1875-1964), and patented in 1894 in collaboration with his brother Birger Ljungström.The design is essentially a multi-stage radial turbine (or a pair of "nested" turbine rotors), high efficiency, four times the heat drop per stage of a reactive (Parsons) turbine, extremely compact design and type in particular success with backpressure power plants.

However, contrary to other designs, large steam volumes are difficult to handle, and only in combination with an axial turbine (DUREX) can the turbine power exceed 50 MW.In marine applications, only about 50 turboelectric units were ordered in 1917-19 (a considerable number were eventually sold to onshore factories), while some turbomachinery units were sold in 1920-22, but not very successfully.In the late 1960s, only a few turbine-electric marine power plants were still in use (ss Ragne, ss Regin), while most land-based power plants were still in use in 2010.Statorless turbines.A multi-stage turbine has a set of static (meaning stationary) inlet guide vanes that direct the airflow onto the rotating rotor blades.In a statorless turbine, the airflow leaving the upstream rotor hits the downstream rotor without encountering an intermediate set of stator blades (rearranging the pressure/velocity energy levels of the airflow).Ceramic turbine.Traditional high-pressure turbine blades (and blades) are made of nickel-based alloys and often use complex internal air-cooling passages to keep the metal from overheating.In recent years, experimental ceramic blades have been fabricated and tested in gas turbines to increase rotor inlet temperatures and/or possibly eliminate air cooling.Ceramic blades are more brittle than metal blades and carry a greater risk of catastrophic blade failure.This tends to limit their use in jet engines and gas turbines to stator (stationary) blades.Turbine with cover.Many turbine rotor blades have shrouds on top that interlock with the shrouds of adjacent blades to increase damping and thus reduce blade flutter.In large land-based power generation steam turbines shrouds are often supplemented with bracing wire, especially in the long blades of low pressur turbines.These wires pass through holes drilled in the blade, an appropriate distance from the root of the blade, and are usually brazed to the blade where they pass.The ties reduce blade chatter in the center portion of the blade.The introduction of ties greatly reduces the instances of blade failure in large or low pressure turbines.Unshrouded turbine.Modern practice is to eliminate rotor shrouds wherever possible, thereby reducing centrifugal loads and cooling requirements on the blades.Bladeless turbines use boundary layer effects instead of fluid impinging on the blades like conventional turbines.

• Water turbine

• Pelton Turbine, a type of Pelton Turbine.

• Francis turbine, a widely used type of water turbine

• Axial turbines, a variant of Francis turbines.

• Turgo turbine, a modified form of the Pelton turbine.

• Cross-flow turbines, also known as Banki-Michell turbines or Ossberger turbines.

• Wind turbine.These typically operate as a single stage, without nozzles and interstage vanes.The exception is Éolienne Bollée, which has a stator and a rotor.Speed Compound "Curtis".Curtis combines de Laval and Parsons turbines by using a fixed set of nozzles on the first stage or stator, followed by a series of fixed and rotating blade rows, as in Parsons or de Laval, usually up to ten rather than up to A row dred stage of Parsons design.The overall efficiency of the Curtis design is lower than that of a Parsons or de Laval design,but it can operate satisfactorily over a wider speed range, including successfully at low speeds and pressures, making it well suited for use in marine powerplants.In the Curtis arrangement, the entire heat drop in the steam occurs in the initial row of nozzles, and the subsequent rows of moving and stationary blades only redirect the steam.Using a small section of a Curtiss unit, usually a nozzle section and two or three rows of moving blades, often called a Curtiss "wheel", in this form the Curtiss finds widespread use at sea Many reactive and impulse turbines and turbomachines.This practice is still common today in marine steam equipment. Pressure compounded multistage pulse, or "Rateau", named after its French inventor, Auguste Rateau.The Rateau employs simple impulse rotors separated by nozzle diaphragms.Diaphragms are essentially the partitions in a turbine into which a series of tunnels are cut, funnel-shaped, with the wide end facing the previous stage and the narrow end facing the next stage, they are also angled to direct the jet of steam onto the impulsive rotor.Mercury steam turbines use mercury as the working fluid to increase the efficiency of fossil fuel power plants.Although some power plants were built using a combination of mercury vapor and traditional steam turbines, the toxicity of metallic mercury quickly became apparent.A screw turbine is a type of water turbine that uses the Archimedes screw principle to convert the potential energy of the upstream water level into kinetic energy.