A Siemens steam turbine with the case opened.

A turbine is a rotary engine that extracts energy from a fluid flow. Claude Burdin (1788-1873) coined the term from the Latin turbo, or vortex, during an 1828 engineering competition. Benoit Fourneyron (1802-1867), a student of Claude Burdin, built the first practical water turbine. Image File history File links Download high-resolution version (1779x2126, 1759 KB) Mounting of a steam turbine produced by Siemens, Germany Photo taken from [1] with the friendly permission of Siemens Germany by Christian Kuhna, E-Mail: christian. ... Image File history File links Download high-resolution version (1779x2126, 1759 KB) Mounting of a steam turbine produced by Siemens, Germany Photo taken from [1] with the friendly permission of Siemens Germany by Christian Kuhna, E-Mail: christian. ... Siemens redirects here. ... For other uses, see Engine (disambiguation). ... This box:      A fluid is defined as a substance that continually deforms (flows) under an applied shear stress regardless of how small the applied stress. ... For other uses, see Latins and Latin (disambiguation). ... Vortex created by the passage of an aircraft wing, revealed by coloured smoke A vortex (pl. ... Bénoit Fourneyron was born in Saint-Étienne, France in 1802. ...

The simplest turbines have one moving part, a rotor assembly, which is a shaft with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they rotate and impart energy to the rotor. Early turbine examples are windmills and water wheels. This article is about machines that convert wind energy into mechanical energy. ... An overshot water wheel standing 42 feet high powers the Old Mill at Berry College in Rome, Georgia A water wheel (also waterwheel, Norse mill, Persian wheel or noria) is a hydropower system; a system for extracting power from a flow of water. ...

Gas, steam, and water turbines have a casing around the blades that contains and controls the working fluid. Credit for invention of the modern steam turbine is given to British Engineer Sir Charles Parsons (1854 - 1931). This machine has a single-stage centrifugal compressor and turbine, a recuperator, and foil bearings. ... A rotor of a modern steam turbine, used in a power plant A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work. ... Kaplan turbine and electrical generator cut-away view. ... Charles Algernon Parsons Compund Steam Turbine, circa 1887 Sir Charles Algernon Parsons, O.M. (June 13, 1854 – February 11, 1931) was a British engineer, best known for his invention of the steam turbine. ...

A device similar to a turbine but operating in reverse is a compressor or pump. The axial compressor in many gas turbine engines is a common example. A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. ... This article is about a mechanical device. ... This article does not cite any references or sources. ... This machine has a single-stage centrifugal compressor and turbine, a recuperator, and foil bearings. ...

Theory of operation

A working fluid contains potential energy (pressure head) and kinetic energy (velocity head). The fluid may be compressible or incompressible. Several physical principles are employed by turbines to collect this energy: Image File history File links Download high resolution version (572x684, 41 KB) Summary Schematic diagram summarising the differences between impulse and reaction turbines. ... Potential energy can be thought of as energy stored within a physical system. ... In fluid dynamics, head refers to the constant right hand side in the incompressible steady version of Bernoullis equation. ... The cars of a roller coaster reach their maximum kinetic energy when at the bottom of their path. ... Fluid Dynamics Compressibility (physics) is a measure of the relative volume change of fluid or solid as a response to a pressure (or mean stress) change: . For a gas the magnitude of the compressibility depends strongly on whether the process is adiabatic or isothermal, while this difference is small in... In fluid mechanics, an incompressible fluid is a fluid whose density (often represented by the Greek letter ρ) is constant: it is the same throughout the field and it does not change through time. ...

Impulse turbines 

These turbines change the direction of flow of a high velocity fluid jet. The resulting impulse spins the turbine and leaves the fluid flow with diminished kinetic energy. There is no pressure change of the fluid in the turbine rotor blades. Before reaching the turbine the fluid's pressure head is changed to velocity head by accelerating the fluid with a nozzle. Pelton wheels and de Laval turbines use this process exclusively. Impulse turbines do not require a pressure casement around the runner since the fluid jet is prepared by a nozzle prior to reaching turbine. Newton's second law describes the transfer of energy for impulse turbines.

Reaction turbines 

These turbines develop torque by reacting to the fluid's pressure or weight. The pressure of the fluid changes as it passes through the turbine rotor blades. A pressure casement is needed to contain the working fluid as it acts on the turbine stage(s) or the turbine must be fully immersed in the fluid flow (wind turbines). The casing contains and directs the working fluid and, for water turbines, maintains the suction imparted by the draft tube. Francis turbines and most steam turbines use this concept. For compressible working fluids, multiple turbine stages may be used to harness the expanding gas efficiently. Newton's third law describes the transfer of energy for reaction turbines.

Turbine designs will use both these concepts to varying degrees whenever possible. Wind turbines use an airfoil to generate lift from the moving fluid and impart it to the rotor (this is a form of reaction). Wind turbines also gain some energy from the impulse of the wind, by deflecting it at an angle. Crossflow turbines are designed as an impulse machine, with a nozzle, but in low head applications maintain some efficiency through reaction, like a traditional water wheel. Turbines with multiple stages may utilize either reaction or impulse blading at high pressure. Steam Turbines were traditionally more impulse but continue to move towards reaction designs similar to those used in Gas Turbines. At low pressure the operating fluid medium expands in volume for small reductions in pressure. Under these conditions (termed Low Pressure Turbines) blading becomes strictly a reaction type design with the base of the blade solely impulse. The reason is due to the effect of the rotation speed for each blade. As the volume increases, the blade height increases, and the base of the blade spins at a slower speed relative to the tip. This change in speed forces a designer to change from impulse at the base, to a high reaction style tip. For other uses, see Impulse (disambiguation). ... Rocket Nozzle A nozzle is a mechanical device designed to control the characteristics of a fluid flow as it exits from an enclosed chamber into some medium. ... Pelton wheel from Walchensee, Germany hydro power station Figure from Peltons original patent (October 1880) Plan view of a Pelton turbine installation (courtesy Voith Siemens Hydro Power Generation). ... A rotor of a modern steam turbine, used in a power plant A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work. ... Newtons First and Second laws, in Latin, from the original 1687 edition of the Principia Mathematica. ... In classical mechanics, Newtons third law states that forces occur in pairs, one called the Action and the other the Reaction (actio et reactio in Latin). ... For other senses of this word, see torque (disambiguation). ... Francis turbine (courtsey Voith-Siemens). ... A rotor of a modern steam turbine, used in a power plant A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work. ... Newtons First and Second laws, in Latin, from the original 1687 edition of the Principia Mathematica. ... Wind turbines near Aalborg, Denmark. ... For the kite, see foil kite. ... The lift force, or simply lift, is a mechanical force, generated by a solid object as it moves through a fluid, directed perpendicular to the flow direction. ... Banki turbine - Wikipedia /**/ @import /w/skins-1. ...

Classical turbine design methods were developed in the mid 19th century. Vector analysis related the fluid flow with turbine shape and rotation. Graphical calculation methods were used at first. Formulas for the basic dimensions of turbine parts are well documented and a highly efficient machine can be reliably designed for any fluid flow condition. Some of the calculations are empirical or 'rule of thumb' formulae, and others are based on classical mechanics. As with most engineering calculations, simplifying assumptions were made. Classical mechanics (commonly confused with Newtonian mechanics, which is a subfield thereof) is used for describing the motion of macroscopic objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars, and galaxies. ...

Velocity triangles can be used to calculate the basic performance of a turbine stage. Gas exits the stationary turbine nozzle guide vanes at absolute velocity V_a1. The rotor rotates at velocity U. Relative to the rotor, the velocity of the gas as it impinges on the rotor entrance is V_r1. The gas is turned by the rotor and exits, relative to the rotor, at velocity V_r2. However, in absolute terms the rotor exit velocity is V_a2. The velocity triangles are constructed using these various velocity vectors. Velocity triangles can be constructed at any section through the blading (for example: hub , tip, midsection and so on) but are usually shown at the mean stage radius. Mean performance for the stage can be calculated from the velocity triangles, at this radius, using the Euler equation:

Typical velocity triangles for a single turbine stage

Whence: Image File history File links Turbinengvrotor. ...

where:

specific enthalpy drop across stage

turbine entry total (or stagnation) temperature

turbine rotor peripheral velocity

change in whirl velocity

The turbine pressure ratio is a function of and the turbine efficiency.

Modern turbine design carries the calculations further. Computational fluid dynamics dispenses with many of the simplifying assumptions used to derive classical formulas and computer software facilitates optimization. These tools have led to steady improvements in turbine design over the last forty years. A computer simulation of high velocity air flow around the Space Shuttle during re-entry. ...

The primary numerical classification of a turbine is its specific speed. This number describes the speed of the turbine at its maximum efficiency with respect to the power and flow rate. The specific speed is derived to be independent of turbine size. Given the fluid flow conditions and the desired shaft output speed, the specific speed can be calculated and an appropriate turbine design selected.

The specific speed, along with some fundamental formulas can be used to reliably scale an existing design of known performance to a new size with corresponding performance.

Off-design performance is normally displayed as a turbine map or characteristic. IF NECESSARY, DOUBLE CLICK ON THUBNAIL IMAGES TO GET A CLEARER VIEW Introduction Each turbine in a gas turbine engine has an operating map. ...

Types of turbines

• Steam turbines are used for the generation of electricity in thermal power plants, such as plants using coal or fuel oil or nuclear power. They were once used to directly drive mechanical devices such as ship's propellors (eg the Turbinia), 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 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 gasflow in most turbines employed in gas turbine engines remains subsonic throughout the expansion process. In a transonic turbine the gasflow 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. This turbine works well in creating power from water.
• Contra-rotating turbines. Some efficiency advantage can be obtained if a downstream turbine rotates in the opposite direction to an upstream unit. However, the complication may be counter-productive.
• Statorless turbine Multi-stage turbines have a set of static (meaning stationary) inlet guide vanes that direct the gasflow onto the rotating rotor blades. In a statorless turbine the gasflow 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-steel alloys and often utilise intricate internal air-cooling passages to prevent the metal from melting. 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 aircooling. Ceramic blades are more brittle than their metallic counterparts, and carry a greater risk of catastrophic blade failure.
• Shrouded turbine. Many turbine rotor blades have a shroud at the top, which interlocks with that of adjacent blades, to increase damping and thereby reduce blade flutter.
• Shroudless turbine. Modern practise is, where possible, to eliminate the rotor shroud, thus reducing the centrifugal load on the blade and the cooling requirements.
• Bladeless turbine uses the boundary layer effect and not a fluid impinging upon the blades as in a conventional turbine.
• Water turbines
  • Pelton turbine, a type of impulse water turbine.
  • Francis turbine, a type of widely used water turbine.
  • Kaplan turbine, a variation of the Francis Turbine.
• Wind turbine. These normally operate as a single stage without nozzle and interstage guide vanes. An exception is the Éolienne Bollée, which has a stator and a rotor, thus being a true turbine.

A rotor of a modern steam turbine, used in a power plant A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work. ... A power station (also power plant) is a facility for the generation of electric power. ... Coal Example chemical structure of coal Coal is a fossil fuel formed in ecosystems where plant remains were saved by water and mud from oxidization and biodegradation. ... -1... This article is about applications of nuclear fission reactors as power sources. ... A propeller can be seen as a rotating fin in water or a wing in air. ... Turbinia was the first steam turbine powered steamship, built as an experimental vessel in 1894 and demonstrated dramatically at the Spithead Navy Review in 1897, setting the standard for the next generation of steamships. ... For other kinds of motors, see motor. ... This machine has a single-stage centrifugal compressor and turbine, a recuperator, and foil bearings. ... Transonic is an aeronautics term referring to a range of velocities just below and above the speed of sound. ... Categories: Aircraft stubs ... The stator is the fixed part of a rotating machine. ... This article is about ceramic materials. ... A ducted fan is an arrangement of a propeller-driven aircraft where the propeller is mounted inside the fuselage, within a duct. ... A ducted fan is an arrangement of a propeller-driven aircraft where the propeller is mounted inside the fuselage, within a duct. ... A shroud is typically something, usually a cloth, that covers or protects some other object. ... The expression centrifugal force is used to express that if an object is being swung around on a string the object seems to be pulling on the string. ... The Tesla turbine is a bladeless turbine design patented by Nikola Tesla in 1913. ... Kaplan turbine and electrical generator cut-away view. ... Pelton wheel from Walchensee, Germany hydro power station Figure from Peltons original patent (October 1880) Plan view of a Pelton turbine installation (courtesy Voith Siemens Hydro Power Generation). ... Francis turbine (courtsey Voith-Siemens). ... A Bonneville Dam Kaplan turbine after 61 years of service The Kaplan turbine is a propeller-type water turbine that has adjustable blades. ... Wind turbines near Aalborg, Denmark. ...

Other

• Velocity compound "Curtis". Curtis combined the de Laval and Parsons turbine by using a set of fixed nozzles on the first stage or stator and then a rank of fixed and rotating stators as in the Parsons, typically up to ten compared with up to a hundred stages, however the efficiency of the turbine was less than that of the Parsons but it operated at much lower speeds and at lower pressures which made it ideal for ships. Note that the use of a small section of a Curtis, typically one nozzle section and two rotors is termed a "Curtis Wheel"
• Pressure Compund Multistage Impulse or Rateau. The Rateau employs simple Impulse rotors separated by a nozzle diaphragm. The diaphragm is essentially a partition wall in the turbine with a series of tunnels cut into it, funnel shaped with the broad end facing the previous stage and the narrow the next they are also angled to direct the steam jets onto the impulse rotor.

Uses of turbines

Almost all electrical power on Earth is produced with a turbine of some type. Very high efficiency turbines harness about 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. A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ...

Turbines are often part of a larger machine. A gas turbine, for example, may refer to an internal combustion machine that contains a turbine, ducts, compressor, combustor, heat-exchanger, fan and (in the case of one designed to produce electricity) an alternator. However, it must be noted that the collective machine referred to as the turbine in these cases is designed to transfer energy from a fuel to the fluid passing through such an internal combustion device as a means of propulsion, and not to transfer energy from the fluid passing through the turbine to the turbine as is the case in turbines used for electricity provision etc. This machine has a single-stage centrifugal compressor and turbine, a recuperator, and foil bearings. ...

Reciprocating piston engines such as aircraft engines can use a turbine powered by their exhaust to drive an intake-air compressor, a configuration known as a turbocharger (turbine supercharger) or, colloquially, a "turbo". To meet Wikipedias quality standards, this article or section may require cleanup. ... Turbo redirects here. ... A supercharger (or blower ) is a gas compressor that forces more air into the combustion chamber(s) of an internal combustion engine than is achievable with ambient atmospheric pressure (as seen in a naturally-aspirated engine, see forced induction). ...

Turbines can have very high power density (ie the ratio of power to weight, or power to volume). This is because of their ability to operate at very high speeds. The Space Shuttle's main engines use turbopumps (machines consisting of a pump driven by a turbine engine) to feed the propellants (liquid oxygen and liquid hydrogen) into the engine's combustion chamber. The liquid hydrogen turbopump is slightly larger than an automobile engine (weighing approximately 700 lb) and produces nearly 70,000 hp (52.2 MW). This article is about the space vehicle. ... A turbopump can refer to either of two types of pump. ... hp redirects here. ... The megawatt (symbol: MW) is a unit for measuring power corresponding to one million (106) watts. ...

Turboexpanders are widely used as sources of refrigeration in industrial processes. A turboexpander, also referred to as a turbo expander, expansion turbine or simply expander, is a centrifugal or axial flow turbine through which a high pressure gas is expanded to produce work that is typically used to drive a compressor. ...

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Turbine

Turbines could also be used as powering system for a remote controlled plane that creates thrust and lifts the plane of the ground. They come in different sizes and could be as small as soda can, still be strong enough to move objects with a weight of 100kg.

Shrouded tidal turbines

An emerging renewable energy technology is the shrouded tidal turbine enclosed in a venturi shaped shroud or duct producing a sub atmosphere of low pressure behind the turbine, allowing the turbine to operate at higher efficiency (than the Betz limit ^[1] of 59.3%) and typically 3 times higher power output ^[2] than a turbine of the same size in free stream. A Venturi meter is shown in a diagram, the pressure in 1 conditions is higher than 2, and the relationship between the fluid speed in 2 and 1 respectively, is the same as for pressure. ... // The aerodynamics of a horizontal axis wind turbine are not straight forward. ...

Asymmetric airfoil

As shown in the CFD generated figure^[3], it can be seen that a down stream low pressure (shown by the gradient lines) draws upstream flow into the inlet of the shroud from well outside the inlet of the shroud. This flow is drawn into the shroud and concentrated (as seen by the red coloured zone). This augmentation of flow velocity corresponds to a 3-4 times increase in energy available to the turbine. Therefore a turbine located in the throat of the shroud is then able to achieve higher efficiency, and an output 3-4 times the energy the turbine would be capable of if it were in open or free stream. For this reason shrouded turbines are not subject to the properties of the Betz limit. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... A computer simulation of high velocity air flow around the Space Shuttle during re-entry. ...

Considerable commercial interest has been shown in recent times in shrouded tidal turbines as it allows a smaller turbine to be used at sites where large turbines are restricted. Arrayed across a seaway or in fast flowing rivers shrouded tidal turbines are easily cabled to a terrestrial base and connected to a grid or remote community. Alternatively the property of the shroud that produces an accelerated flow velocity across the turbine allows tidal flows formerly too slow for commercial use to be utilised for commercial energy production.

While the shroud may not be practical in wind, as a tidal turbine it is gaining more popularity and commercial use. A shrouded tidal turbine is mono directional and constantly needs to face upstream in order to operate. It can be floated under a pontoon on a swing mooring, fixed to the seabed on a mono pile and yawed like a wind sock to continually face upstream. A shroud can also be built into a tidal fence increasing the performance of the turbines.

Cabled to the mainland they can be grid connected or can be scaled down to provide energy to remote communities where large civil infrastructures are not viable. Similarly to tidal stream open turbines they have little if any environmental or visual amenity impact.

See also

• Rotordynamics
• Turbo-alternator
• Turbinia
• RMS Lusitania
• Secondary flow in turbines

Rotordynamics is a specialized branch of applied mechanics concerned with the behavior and diagnosis of rotating structures. ... Turbinia was the first steam turbine powered steamship, built as an experimental vessel in 1894 and demonstrated dramatically at the Spithead Navy Review in 1897, setting the standard for the next generation of steamships. ... RMS Lusitania was a British luxury ocean liner owned by the Cunard Steamship Company and built by John Brown and Company of Clydebank, Scotland. ...

Notes

External links

• Turbine introductory math
• Turbines jet powered 1/16 scale Airbus A330
• Turbine working process