A gas turbine, also called a combustion turbine, is a type of continuous flow

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combus ...

. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the direction of flow: * a rotating

gas compressor A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. Compressors are similar to pumps: both increase the pressure on a fluid and both can tran ...

* a

combustor A combustor is a component or area of a gas turbine, ramjet, or scramjet engine where combustion takes place. It is also known as a burner, combustion chamber or flame holder. In a gas turbine engine, the ''combustor'' or combustion chamber is f ...

* a compressor-driving

turbine A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) 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 ...

. Additional components have to be added to the gas generator to suit its application. Common to all is an air inlet but with different configurations to suit the requirements of marine use, land use or flight at speeds varying from stationary to supersonic. A propelling nozzle is added to produce thrust for flight. An extra turbine is added to drive a propeller (

turboprop A turboprop is a turbine engine that drives an aircraft propeller. A turboprop consists of an intake, reduction gearbox, compressor, combustor, turbine, and a propelling nozzle. Air enters the intake and is compressed by the compressor. Fuel ...

) or ducted fan (

turbofan The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which ac ...

) to reduce fuel consumption (by increasing propulsive efficiency) at subsonic flight speeds. An extra turbine is also required to drive a helicopter rotor or land-vehicle transmission (

turboshaft A turboshaft engine is a form of gas turbine that is optimized to produce shaftpower rather than jet thrust. In concept, turboshaft engines are very similar to turbojets, with additional turbine expansion to extract heat energy from the exhaust ...

), marine propeller or electrical generator (power turbine). Greater

thrust-to-weight ratio Thrust-to-weight ratio is a dimensionless ratio of thrust to weight of a rocket, jet engine, propeller engine, or a vehicle propelled by such an engine that is an indicator of the performance of the engine or vehicle. The instantaneous thrust-to- ...

for flight is achieved with the addition of an

afterburner An afterburner (or reheat in British English) is an additional combustion component used on some jet engines, mostly those on military supersonic aircraft. Its purpose is to increase thrust, usually for supersonic flight, takeoff, and comba ...

. The basic operation of the gas turbine is a

Brayton cycle The Brayton cycle is a thermodynamic cycle that describes the operation of certain heat engines that have air or some other gas as their working fluid. The original Brayton engines used a piston compressor and piston expander, but modern gas tu ...

with air as the

working fluid For fluid power, a working fluid is a gas or liquid that primarily transfers force, motion, or mechanical energy. In hydraulics, water or hydraulic fluid transfers force between hydraulic components such as hydraulic pumps, hydraulic cylinders, ...

: atmospheric air flows through the compressor that brings it to higher pressure;

energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...

is then added by spraying fuel into the air and igniting it so that the combustion generates a high-temperature flow; this high-temperature pressurized gas enters a turbine, producing a shaft work output in the process, used to drive the compressor; the unused energy comes out in the exhaust gases that can be repurposed for external work, such as directly producing

thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that syst ...

in a

turbojet engine The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...

, or rotating a second, independent turbine (known as a ''power turbine'') that can be connected to a fan, propeller, or electrical generator. The purpose of the gas turbine determines the design so that the most desirable split of energy between the thrust and the shaft work is achieved. The fourth step of the Brayton cycle (cooling of the working fluid) is omitted, as gas turbines are open systems that do not reuse the same air. Gas turbines are used to power aircraft, trains, ships, electrical generators, pumps, gas compressors, and

tank A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and good battlefield mobility provided by tracks and a powerful engin ...

Timeline of development

*50: Earliest records of

Hero's Hero's was a Japanese mixed martial arts promotion operated by Fighting and Entertainment Group, the parent entity behind kickboxing organization K-1. Grown from and branched off of K-1's earlier experiments in MMA, including the ''K-1 Romanex' ...

engine (''

aeolipile An aeolipile, aeolipyle, or eolipile, from the Greek "αιολουπυλη", also known as a Hero's engine, is a simple, bladeless radial steam turbine which spins when the central water container is heated. Torque is produced by steam jets exi ...

''). It most likely served no practical purpose, and was rather more of a curiosity; nonetheless, it demonstrated an important principle of physics that all modern turbine engines rely on. *1000: The "Trotting Horse Lamp" (, ''zŏumădēng'') was used by the Chinese at lantern fairs as early as the

Northern Song dynasty Northern may refer to the following: Geography * North, a point in direction * Northern Europe, the northern part or region of Europe * Northern Highland, a region of Wisconsin, United States * Northern Province, Sri Lanka * Northern Range, a ...

. When the lamp is lit, the heated airflow rises and drives an impeller with horse-riding figures attached on it, whose shadows are then projected onto the outer screen of the lantern. *1500: The ''

Smoke jack A roasting jack is a machine which rotates meat roasting on a spit. It can also be called a spit jack, a spit engine or a turnspit, although this name can also refer to a human turning the spit, or a turnspit dog. Cooking meat on a spit dates ...

'' was drawn by

Leonardo da Vinci Leonardo di ser Piero da Vinci (15 April 14522 May 1519) was an Italian polymath of the High Renaissance who was active as a painter, Drawing, draughtsman, engineer, scientist, theorist, sculptor, and architect. While his fame initially res ...

: Hot air from a fire rises through a single-stage axial turbine rotor mounted in the exhaust duct of the fireplace and turns the roasting spit by gear-chain connection. *1629: Jets of steam rotated an impulse turbine that then drove a working stamping mill by means of a

bevel gear Bevel gears are gears where the axes of the two shafts intersect and the tooth-bearing faces of the gears themselves are conically shaped. Bevel gears are most often mounted on shafts that are 90 degrees apart, but can be designed to work at othe ...

, developed by

Giovanni Branca Giovanni Branca (22 April 1571 – 24 January 1645) was an Italian engineer and architect, chiefly remembered today for what some commentators have taken to be an early steam turbine. Life Branca was born on 22 April 1571 in Sant'Angelo in L ...

. *1678:

Ferdinand Verbiest Father Ferdinand Verbiest (9 October 1623 – 28 January 1688) was a Flemish Jesuit missionary in China during the Qing dynasty. He was born in Pittem near Tielt in the County of Flanders (now part of Belgium). He is known as Nan Huairen () in C ...

built a model carriage relying on a steam jet for power. *1791: A patent was given to John Barber, an Englishman, for the first true gas turbine. His invention had most of the elements present in the modern day gas turbines. The turbine was designed to power a

horseless carriage Horseless carriage is an early name for the car, motor car or automobile. Prior to the invention of the motor car, carriages were usually pulled by animals, typically horses. The term can be compared to other transitional terms, such as mobile ph ...

. *1861: British patent no. 1633 was granted to Marc Antoine Francois Mennons for a "Caloric engine". The patent shows that it was a gas turbine and the drawings show it applied to a locomotive. *1872: A gas turbine engine designed by Berlin engineer,

Franz Stolze Franz may refer to: People * Franz (given name) * Franz (surname) Places * Franz (crater), a lunar crater * Franz, Ontario, a railway junction and unorganized town in Canada * Franz Lake, in the state of Washington, United States – see ...

, is thought to be the first attempt at creating a working model, but the engine never ran under its own power. *1894: Sir Charles Parsons patented the idea of propelling a ship with a

steam turbine A steam turbine is a machine that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Charles Parsons in 1884. Fabrication of a modern steam turbin ...

, and built a demonstration vessel, the ''

Turbinia ''Turbinia'' was the first steam turbine-powered steamship. Built as an experimental vessel in 1894, and easily the fastest ship in the world at that time, ''Turbinia'' was demonstrated dramatically at the Spithead Navy Review in 1897 and set ...

'', easily the fastest vessel afloat at the time. This principle of propulsion is still of some use. *1895: Three 4-ton 100 kW Parsons radial flow generators were installed in

Cambridge Cambridge ( ) is a university city and the county town in Cambridgeshire, England. It is located on the River Cam approximately north of London. As of the 2021 United Kingdom census, the population of Cambridge was 145,700. Cambridge bec ...

Power Station, and used to power the first electric street lighting scheme in the city. *1899:

Charles Gordon Curtis Charles Gordon Curtis (April 20, 1860 in Boston – March 1953 in Central Islip, Suffolk County, New York) was an American engineer, inventor, and patent attorney. He is best known as the developer of the eponymous Curtis steam turbine. Early ...

patented the first gas turbine engine in the US ("Apparatus for generating mechanical power", Patent No. US635,919). *1900:

Sanford Alexander Moss Sanford Alexander Moss (August 23, 1872 – November 10, 1946) was an American aviation engineer, who was the first to use a turbocharger on an aircraft engine. Life and career Sanford Moss was born 1872 in San Francisco, California to Ernest ...

submitted a thesis on gas turbines. In 1903, Moss became an engineer for

General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...

's Steam Turbine Department in

Lynn, Massachusetts Lynn is the eighth-largest municipality in Massachusetts and the largest city in Essex County. Situated on the Atlantic Ocean, north of the Boston city line at Suffolk Downs, Lynn is part of Greater Boston's urban inner core. Settled by E ...

.Leyes, p.231-232. While there, he applied some of his concepts in the development of the

turbosupercharger In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pro ...

. His design used a small turbine wheel, driven by exhaust gases, to turn a supercharger. *1903: A Norwegian,

Ægidius Elling Jens William Ægidius Elling (also Aegidus or Aegidius) (26 July 1861 – 27 May 1949) was a Norwegian researcher, inventor and pioneer of gas turbines who is considered to be the father of the gas turbine. He built the first gas turbine that w ...

, built the first gas turbine that was able to produce more power than needed to run its own components, which was considered an achievement in a time when knowledge about aerodynamics was limited. Using rotary compressors and turbines it produced 11 hp.Bakken, Lars E et al., p.83-88. "Centenary of the First Gas Turbine to Give Net Power Output: A Tribute to Ægidius Elling". ASME. 2004 *1906: The Armengaud-Lemale turbine engine in France with a water-cooled combustion chamber. *1910: Holzwarth impulse turbine (pulse combustion) achieved . *1913:

Nikola Tesla Nikola Tesla ( ; ,"Tesla"
''

Tesla turbine Tesla turbine at Nikola Tesla Museum The Tesla turbine is a bladeless centripetal flow turbine patented by Nikola Tesla in 1913. It is referred to as a ''bladeless turbine''. The Tesla turbine also known as the ''boundary-layer turbine'', ''c ...

based on the

boundary layer In physics and fluid mechanics, a boundary layer is the thin layer of fluid in the immediate vicinity of a bounding surface formed by the fluid flowing along the surface. The fluid's interaction with the wall induces a no-slip boundary condi ...

effect. *1920s The practical theory of gas flow through passages was developed into the more formal (and applicable to turbines) theory of gas flow past airfoils by A. A. Griffith resulting in the publishing in 1926 of ''An Aerodynamic Theory of Turbine Design''. Working testbed designs of axial turbines suitable for driving a propeller were developed by the Royal Aeronautical Establishment, thereby proving the efficiency of aerodynamic shaping of the blades in 1929. *1930: Having found no interest from the RAF for his idea,

Frank Whittle Air Commodore Sir Frank Whittle, (1 June 1907 – 8 August 1996) was an English engineer, inventor and Royal Air Force (RAF) air officer. He is credited with inventing the turbojet engine. A patent was submitted by Maxime Guillaume in 1921 for ...

patented the design for a centrifugal gas turbine for

jet propulsion Jet propulsion is the propulsion of an object in one direction, produced by ejecting a jet of fluid in the opposite direction. By Newton's third law, the moving body is propelled in the opposite direction to the jet. Reaction engines operating o ...

. The first successful use of his engine occurred in England in April 1937. *1932: BBC

Brown, Boveri & Cie Brown, Boveri & Cie. (Brown, Boveri & Company; BBC) was a Swiss group of electrical engineering companies. It was founded in Zürich, in 1891 by Charles Eugene Lancelot Brown and Walter Boveri who worked at the Maschinenfabrik Oerlikon. In 1 ...

of Switzerland starts selling axial compressor and turbine turbosets as part of the turbocharged steam generating

Velox boiler A Velox boiler is a high pressure, forced circulation, water-tube boiler. It was developed in 1930s by Brown Boveri Company of Switzerland. The first public demonstration of Velox was at VDI Scientific Conference in Berlin on 15 October 1932. D ...

. Following the gas turbine principle, the steam

evaporation Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...

tubes are arranged within the gas turbine combustion chamber; the first Velox plant was erected in Mondeville, Calvados, France. *1934: Raúl Pateras de Pescara patented the

free-piston engine A free-piston engine is a linear, 'crankless' internal combustion engine, in which the piston motion is not controlled by a crankshaft but determined by the interaction of forces from the combustion chamber gases, a rebound device (e.g., a piston ...

as a gas generator for gas turbines. *1936: Whittle with others backed by investment forms Power Jets Ltd *1937: Working proof-of-concept prototype jet engine runs in UK (Frank Whittle's) and Germany (

Hans von Ohain Hans Joachim Pabst von Ohain (14 December 191113 March 1998) was a German physicist, engineer, and the designer of the first operational jet engine. Together with Frank Whittle he is called the "father of the jet engine". His first test unit ran ...

Heinkel HeS 1 The Heinkel HeS 1 ''(HeS - Heinkel Strahltriebwerke)'' was Germany's first jet engine, which was a stationary test item that ran on hydrogen. History In 1933, Hans von Ohain wrote his PhD thesis at the University of Göttingen on the topic of an ...

Henry Tizard Sir Henry Thomas Tizard (23 August 1885 – 9 October 1959) was an English chemist, inventor and Rector of Imperial College, who developed the modern "octane rating" used to classify petrol, helped develop radar in World War II, and led the fir ...

secures UK government funding for further development of ''Power Jets'' engine.John Golley. 1996. "Jet: Frank Whittle and the invention of the jet engine". *1939: First 4 MW utility power generation gas turbine from BBC Brown, Boveri & Cie. for an emergency power station in Neuchâtel, Switzerland. *1944: The Junkers Jumo 004 engine enters full production, powering the first German military jets such as the

Messerschmitt Me 262 The Messerschmitt Me 262, nicknamed ''Schwalbe'' (German: "Swallow") in fighter versions, or ''Sturmvogel'' (German: "Storm Bird") in fighter-bomber versions, is a fighter aircraft and fighter-bomber that was designed and produced by the Germa ...

. This marks the beginning of the reign of gas turbines in the sky. *1946:

National Gas Turbine Establishment The National Gas Turbine Establishment (NGTE Pyestock) in Farnborough, part of the Royal Aircraft Establishment (RAE), was the prime site in the UK for design and development of gas turbine and jet engines. It was created by merging the design te ...

formed from Power Jets and the RAE turbine division to bring together Whittle and

Hayne Constant Hayne Constant, CB, CBE., MA., FRAeS., FRS, (26 September 1904 – 12 January 1968) was an English mechanical and aeronautical engineer who developed jet engines during World War II. Education Constant was born at Gravesend, the son of Frede ...

's work. In Beznau, Switzerland the first commercial reheated/recuperated unit generating 27 MW was commissioned. *1947: A

Metropolitan Vickers Metropolitan-Vickers, Metrovick, or Metrovicks, was a British heavy electrical engineering company of the early-to-mid 20th century formerly known as British Westinghouse. Highly diversified, it was particularly well known for its industrial ...

G1 (Gatric) becomes the first marine gas turbine when it completes sea trials on the Royal Navy's M.G.B 2009 vessel. The Gatric was an aeroderivative gas turbine based on the Metropolitan Vickers F2 jet engine. *1995:

Siemens Siemens AG ( ) is a German multinational conglomerate corporation and the largest industrial manufacturing company in Europe headquartered in Munich with branch offices abroad. The principal divisions of the corporation are ''Industry'', '' ...

becomes the first manufacturer of large electricity producing gas turbines to incorporate

single crystal In materials science, a single crystal (or single-crystal solid or monocrystalline solid) is a material in which the crystal lattice of the entire sample is continuous and unbroken to the edges of the sample, with no grain boundaries.RIWD. "Re ...

turbine blade ...

technology into their production models, allowing higher operating temperatures and greater efficiency. *2011

Mitsubishi Heavy Industries is a Japanese multinational engineering, electrical equipment and electronics corporation headquartered in Tokyo, Japan. MHI is one of the core companies of the Mitsubishi Group and its automobile division is the predecessor of Mitsubishi Mo ...

tests the first >60% efficiency combined cycle gas turbine (the M501J) at its Takasago, Hyōgo, works.

Theory of operation

In an ideal gas turbine, gases undergo four

thermodynamic Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of the ...

processes: an

isentropic In thermodynamics, an isentropic process is an idealized thermodynamic process that is both adiabatic and reversible. The work transfers of the system are frictionless, and there is no net transfer of heat or matter. Such an idealized process ...

compression, an

isobaric Isobar may refer to: * Isobar (meteorology), a line connecting points of equal atmospheric pressure reduced to sea level on the maps. * Isobaric process In thermodynamics, an isobaric process is a type of thermodynamic process in which the pr ...

(constant pressure) combustion, an isentropic expansion and heat rejection. Together, these make up the

. In a real gas turbine, mechanical energy is changed irreversibly (due to internal friction and turbulence) into pressure and thermal energy when the gas is compressed (in either a centrifugal or axial compressor). Heat is added in the

combustion chamber A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process. Intern ...

and the

specific volume In thermodynamics, the specific volume of a substance (symbol: , nu) is an intrinsic property of the substance, defined as the ratio of the substance's volume () to its mass (). It is the reciprocal of density (rho) and it is related to the m ...

of the gas increases, accompanied by a slight loss in pressure. During expansion through the stator and rotor passages in the turbine, irreversible energy transformation once again occurs. Fresh air is taken in, in place of the heat rejection. If the engine has a power turbine added to drive an industrial generator or a helicopter rotor, the exit pressure will be as close to the entry pressure as possible with only enough energy left to overcome the pressure losses in the exhaust ducting and expel the exhaust. For a

engine there will be a particular balance between propeller power and jet thrust which gives the most economical operation. In a

only enough pressure and energy is extracted from the flow to drive the compressor and other components. The remaining high-pressure gases are accelerated through a nozzle to provide a jet to propel an aircraft. The smaller the engine, the higher the rotation rate of the shaft must be to attain the required blade tip speed. Blade-tip speed determines the maximum pressure ratios that can be obtained by the turbine and the compressor. This, in turn, limits the maximum power and efficiency that can be obtained by the engine. In order for tip speed to remain constant, if the diameter of a rotor is reduced by half, the

rotational speed Rotational frequency (also known as rotational speed or rate of rotation) of an object Rotation around a fixed axis, rotating around an axis is the frequency of rotation of the object. Its unit is revolution per minute (rpm), cycle per second ...

must double. For example, large jet engines operate around 10,000–25,000 rpm, while micro turbines spin as fast as 500,000 rpm. Mechanically, gas turbines ''can'' be considerably less complex than

internal combustion An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combus ...

piston engines. Simple turbines might have one main moving part, the compressor/shaft/turbine rotor assembly, with other moving parts in the fuel system. This, in turn, can translate into price. For instance, costing for materials, the Jumo 004 proved cheaper than the Junkers 213 piston engine, which was , and needed only 375 hours of lower-skill labor to complete (including manufacture, assembly, and shipping), compared to 1,400 for the

BMW 801 The BMW 801 was a powerful German air-cooled 14-cylinder-radial aircraft engine built by BMW and used in a number of German Luftwaffe aircraft of World War II. Production versions of the twin-row engine generated between 1,560 and 2,000 PS ...

. This, however, also translated into poor efficiency and reliability. More advanced gas turbines (such as those found in modern

jet engines A jet engine is a type of reaction engine discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include rocket, water jet, and hybrid propulsion, the term typicall ...

or combined cycle power plants) may have 2 or 3 shafts (spools), hundreds of compressor and turbine blades, movable stator blades, and extensive external tubing for fuel, oil and air systems; they use temperature resistant alloys, and are made with tight specifications requiring precision manufacture. All this often makes the construction of a simple gas turbine more complicated than a piston engine. Moreover, to reach optimum performance in modern gas turbine power plants the gas needs to be prepared to exact fuel specifications. Fuel gas conditioning systems treat the natural gas to reach the exact fuel specification prior to entering the turbine in terms of pressure, temperature, gas composition, and the related wobbe-index. The primary advantage of a gas turbine engine is its power to weight ratio. Since significant useful work can be generated by a relatively lightweight engine, gas turbines are perfectly suited for aircraft propulsion.

Thrust bearing A thrust bearing is a particular type of rotary bearing. Like other bearings they permanently rotate between parts, but they are designed to support a predominantly axial load. Thrust bearings come in several varieties. *''Thrust ball bearings ...

s and

journal bearings A plain bearing, or more commonly sliding contact bearing and slide bearing (in railroading sometimes called a solid bearing, journal bearing, or friction bearing), is the simplest type of bearing, comprising just a bearing surface and no roll ...

are a critical part of a design. They are hydrodynamic oil bearings or oil-cooled

rolling-element bearing In mechanical engineering, a rolling-element bearing, also known as a rolling bearing, is a bearing which carries a load by placing rolling elements (such as balls or rollers) between two concentric, grooved rings called races. The relative m ...

Foil bearing A foil bearing, also known as a foil-air bearing, is a type of air bearing. A shaft is supported by a compliant, spring-loaded foil journal lining. Once the shaft is spinning fast enough, the working fluid (usually air) pushes the foil away from ...

s are used in some small machines such as micro turbines and also have strong potential for use in small gas turbines/

auxiliary power unit An auxiliary power unit (APU) is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft and naval ships as well as some large land vehicles. Aircraft APUs generally produce 115& ...

Creep

A major challenge facing turbine design, especially turbine blades, is reducing the creep that is induced by the high temperatures and stresses that are experienced during operation. Higher operating temperatures are continuously sought in order to increase efficiency, but come at the cost of higher creep rates. Several methods have therefore been employed in an attempt to achieve optimal performance while limiting creep, with the most successful ones being high performance coatings and single crystal superalloys. These technologies work by limiting deformation that occurs by mechanisms that can be broadly classified as dislocation glide, dislocation climb and diffusional flow. Protective coatings provide thermal insulation of the blade and offer

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

and

corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...

resistance. Thermal barrier coatings (TBCs) are often stabilized

zirconium dioxide Zirconium dioxide (), sometimes known as zirconia (not to be confused with zircon), is a white crystalline oxide of zirconium. Its most naturally occurring form, with a monoclinic crystalline structure, is the mineral baddeleyite. A dopant stabi ...

-based ceramics and oxidation/corrosion resistant coatings (bond coats) typically consist of

aluminide An aluminide is a compound that has aluminium with more electropositive elements. Since aluminium is near the nonmetals on the periodic table, it can bond with metals differently from other metals. The properties of an aluminide are between those ...

s or MCrAlY (where M is typically Fe and/or Cr) alloys. Using TBCs limits the temperature exposure of the superalloy substrate, thereby decreasing the diffusivity of the active species (typically vacancies) within the alloy and reducing dislocation and vacancy creep. It has been found that a coating of 1–200 μm can decrease blade temperatures by up to . Bond coats are directly applied onto the surface of the substrate using pack carburization and serve the dual purpose of providing improved adherence for the TBC and oxidation resistance for the substrate. The Al from the bond coats forms Al₂O₃ on the TBC-bond coat interface which provides the oxidation resistance, but also results in the formation of an undesirable interdiffusion (ID) zone between itself and the substrate. The oxidation resistance outweighs the drawbacks associated with the ID zone as it increases the lifetime of the blade and limits the efficiency losses caused by a buildup on the outside of the blades. Nickel-based superalloys boast improved strength and creep resistance due to their composition and resultant

microstructure Microstructure is the very small scale structure of a material, defined as the structure of a prepared surface of material as revealed by an optical microscope above 25× magnification. The microstructure of a material (such as metals, polymers ...

. The gamma (γ) FCC nickel is alloyed with aluminum and titanium in order to precipitate a uniform dispersion of the coherent gamma-prime (γ') phases. The finely dispersed γ' precipitates impede dislocation motion and introduce a threshold stress, increasing the stress required for the onset of creep. Furthermore, γ' is an ordered L1₂ phase that makes it harder for dislocations to shear past it. Further

Refractory In materials science, a refractory material or refractory is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. Refractories are polycrystalline, polyphase, ...

elements such as

rhenium Rhenium is a chemical element with the symbol Re and atomic number 75. It is a silvery-gray, heavy, third-row transition metal in group 7 of the periodic table. With an estimated average concentration of 1 part per billion (ppb), rhenium is one ...

and

ruthenium Ruthenium is a chemical element with the Symbol (chemistry), symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to ...

can be added in solid solution to improve creep strength. The addition of these elements reduces the diffusion of the gamma prime phase, thus preserving the fatigue resistance, strength, and creep resistance. The development of single crystal superalloys has led to significant improvements in creep resistance as well. Due to the lack of grain boundaries, single crystals eliminate

Coble creep Coble creep, a form of diffusion creep, is a mechanism for deformation of crystalline solids. Contrasted with other diffusional creep mechanisms, Coble creep is similar to Nabarro–Herring creep in that it is dominant at lower stress levels an ...

and consequently deform by fewer modes – decreasing the creep rate. Although single crystals have lower creep at high temperatures, they have significantly lower yield stresses at room temperature where strength is determined by the Hall-Petch relationship. Care needs to be taken in order to optimize the design parameters to limit high temperature creep while not decreasing low temperature yield strength.

Types

Jet engines

Airbreathing

jet engine A jet engine is a type of reaction engine discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include rocket, Pump-jet, water jet, and hybrid propulsion, the term ...

s are gas turbines optimized to produce thrust from the exhaust gases, or from

ducted fan In aeronautics, a ducted fan is a thrust-generating mechanical fan or propeller mounted within a cylindrical duct or shroud. Other terms include ducted propeller or shrouded propeller. When used in vertical takeoff and landing (VTOL) applicatio ...

s connected to the gas turbines. Jet engines that produce thrust from the direct impulse of exhaust gases are often called

turbojet The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...

s, whereas those that generate thrust with the addition of a ducted fan are often called

s or (rarely) fan-jets. Gas turbines are also used in many

liquid fuel rocket A liquid-propellant rocket or liquid rocket utilizes a rocket engine that uses liquid propellants. Liquids are desirable because they have a reasonably high density and high specific impulse (''I''sp). This allows the volume of the propellant ta ...

s, where gas turbines are used to power a

turbopump A turbopump is a propellant pump with two main components: a rotodynamic pump and a driving gas turbine, usually both mounted on the same shaft, or sometimes geared together. They were initially developed in Germany in the early 1940s. The purpo ...

to permit the use of lightweight, low-pressure tanks, reducing the empty weight of the rocket.

Turboprop engines

engine is a turbine engine that drives an aircraft propeller using a reduction gear. Turboprop engines are used on small aircraft such as the general-aviation Cessna 208 Caravan and

Embraer EMB 312 Tucano The Embraer EMB 312 Tucano (English: '' Toucan'') is a low-wing, tandem-seat, single-turboprop, basic trainer with counter-insurgency capability that was developed in Brazil. The Brazilian Air Force sponsored the EMB-312 project at the end of 1 ...

military trainer, medium-sized commuter aircraft such as the

Bombardier Dash 8 The De Havilland Canada DHC-8, commonly known as the Dash 8, is a series of turboprop-powered regional airliners, introduced by de Havilland Canada (DHC) in 1984. DHC was later bought by Boeing in 1988, then by Bombardier in 1992; then by ...

and large aircraft such as the Airbus A400M transport and the 60-year-old Tupolev Tu-95 strategic bomber.

Aeroderivative gas turbines

Aeroderivative gas turbines are generally based on existing aircraft gas turbine engines, and are smaller and lighter than industrial gas turbines. Aeroderivatives are used in electrical power generation due to their ability to be shut down and handle load changes more quickly than industrial machines. They are also used in the marine industry to reduce weight. Common types include the

General Electric LM2500 The General Electric LM2500 is an industrial and marine gas turbine produced by GE Aviation. The LM2500 is a derivative of the General Electric CF6 aircraft engine. As of 2004, the U.S. Navy and at least 29 other navies had used a total of more ...

General Electric LM6000 The General Electric LM6000 is a turboshaft aeroderivative gas turbine engine. The LM6000 is derived from the CF6-80C2 aircraft turbofan. It has additions and modifications designed to make it more suitable for marine propulsion, industrial power ...

, and aeroderivative versions of the

Pratt & Whitney PW4000 The Pratt & Whitney PW4000 is a family of dual-spool, axial-flow, high-bypass turbofan aircraft engines produced by Pratt & Whitney as the successor to the JT9D. It was first run in April 1984, was FAA certified in July 1986, and was introdu ...

and

Rolls-Royce RB211 The Rolls-Royce RB211 is a British family of high-bypass turbofan engines made by Rolls-Royce. The engines are capable of generating of thrust. The RB211 engine was the first production three-spool engine, and turned Rolls-Royce from a sign ...

Amateur gas turbines

Increasing numbers of gas turbines are being used or even constructed by amateurs. In its most straightforward form, these are commercial turbines acquired through military surplus or scrapyard sales, then operated for display as part of the hobby of engine collecting. In its most extreme form, amateurs have even rebuilt engines beyond professional repair and then used them to compete for the land speed record. The simplest form of self-constructed gas turbine employs an automotive

turbocharger In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pro ...

as the core component. A combustion chamber is fabricated and plumbed between the compressor and turbine sections. More sophisticated turbojets are also built, where their thrust and light weight are sufficient to power large model aircraft. The Schreckling design constructs the entire engine from raw materials, including the fabrication of a

centrifugal compressor Centrifugal compressors, sometimes called impeller compressors or radial compressors, are a sub-class of dynamic axisymmetric work-absorbing turbomachinery. They achieve pressure rise by adding energy to the continuous flow of fluid through th ...

wheel from plywood, epoxy and wrapped carbon fibre strands. Several small companies now manufacture small turbines and parts for the amateur. Most turbojet-powered model aircraft are now using these commercial and semi-commercial microturbines, rather than a Schreckling-like home-build.

Auxiliary power units

Small gas turbines are used as

s (APUs) to supply auxiliary power to larger, mobile, machines such as an

aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...

. They supply: * compressed air for air conditioning and ventilation, * compressed air start-up power for larger

s, * mechanical (shaft) power to a gearbox to drive shafted accessories, and * electrical, hydraulic and other power-transmission sources to consuming devices remote from the APU.

Industrial gas turbines for power generation

Industrial gas turbines differ from aeronautical designs in that the frames, bearings, and blading are of heavier construction. They are also much more closely integrated with the devices they power—often an electric generator—and the secondary-energy equipment that is used to recover residual energy (largely heat). They range in size from portable mobile plants to large, complex systems weighing more than a hundred tonnes housed in purpose-built buildings. When the gas turbine is used solely for shaft power, its thermal efficiency is about 30%. However, it may be cheaper to buy electricity than to generate it. Therefore, many engines are used in CHP (Combined Heat and Power) configurations that can be small enough to be integrated into portable

container A container is any receptacle or enclosure for holding a product used in storage, packaging, and transportation, including shipping. Things kept inside of a container are protected on several sides by being inside of its structure. The term ...

configurations. Gas turbines can be particularly efficient when

waste heat Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility ...

from the turbine is recovered by a heat recovery steam generator (HRSG) to power a conventional steam turbine in a combined cycle configuration. The 605 MW

9HA achieved a 62.22% efficiency rate with temperatures as high as . For 2018, GE offers its 826 MW HA at over 64% efficiency in combined cycle due to advances in

additive manufacturing 3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer co ...

and combustion breakthroughs, up from 63.7% in 2017 orders and on track to achieve 65% by the early 2020s. In March 2018, GE Power achieved a 63.08% gross efficiency for its 7HA turbine. Aeroderivative gas turbines can also be used in combined cycles, leading to a higher efficiency, but it will not be as high as a specifically designed industrial gas turbine. They can also be run in a cogeneration configuration: the exhaust is used for space or water heating, or drives an absorption chiller for cooling the inlet air and increase the power output, technology known as turbine inlet air cooling. Another significant advantage is their ability to be turned on and off within minutes, supplying power during peak, or unscheduled, demand. Since single cycle (gas turbine only) power plants are less efficient than combined cycle plants, they are usually used as peaking power plants, which operate anywhere from several hours per day to a few dozen hours per year—depending on the electricity demand and the generating capacity of the region. In areas with a shortage of base-load and load following power plant capacity or with low fuel costs, a gas turbine powerplant may regularly operate most hours of the day. A large single-cycle gas turbine typically produces 100 to 400 megawatts of electric power and has 35–40% thermodynamic efficiency.

Industrial gas turbines for mechanical drive

Industrial gas turbines that are used solely for mechanical drive or used in collaboration with a recovery steam generator differ from power generating sets in that they are often smaller and feature a dual shaft design as opposed to a single shaft. The power range varies from 1 megawatt up to 50 megawatts. These engines are connected directly or via a gearbox to either a pump or compressor assembly. The majority of installations are used within the oil and gas industries. Mechanical drive applications increase efficiency by around 2%. Oil and gas platforms require these engines to drive compressors to inject gas into the wells to force oil up via another bore, or to compress the gas for transportation. They are also often used to provide power for the platform. These platforms do not need to use the engine in collaboration with a CHP system due to getting the gas at an extremely reduced cost (often free from burn off gas). The same companies use pump sets to drive the fluids to land and across pipelines in various intervals.

Compressed air energy storage

One modern development seeks to improve efficiency in another way, by separating the compressor and the turbine with a compressed air store. In a conventional turbine, up to half the generated power is used driving the compressor. In a compressed air energy storage configuration, power, perhaps from a wind farm or bought on the open market at a time of low demand and low price, is used to drive the compressor, and the compressed air released to operate the turbine when required.

Turboshaft engines

Turboshaft engines are used to drive compressors in gas pumping stations and natural gas liquefaction plants. They are also used to power all but the smallest modern helicopters. A primary shaft carries the compressor and its turbine which, together with a combustor, is called a ''Gas Generator''. A separately-spinning power-turbine is usually used to drive the rotor on helicopters. Allowing the gas generator and power turbine/rotor to spin at their own speeds allows more flexibility in their design.

Radial gas turbines

Scale jet engines

Also known as miniature gas turbines or micro-jets. With this in mind the pioneer of modern Micro-Jets, Kurt Schreckling, produced one of the world's first Micro-Turbines, the FD3/67. This engine can produce up to 22 newton (unit), newtons of thrust, and can be built by most mechanically minded people with basic engineering tools, such as a metal lathe.

Microturbines

Evolved from piston engine

s, aircraft auxiliary power unit, APUs or small

s, microturbines are 25 to 500 kilowatt turbines the size of a refrigerator. Microturbines have around 15% engine efficiency, efficiencies without a recuperator, 20 to 30% with one and they can reach 85% combined thermal-electrical efficiency in cogeneration.

External combustion

Most gas turbines are internal combustion engines but it is also possible to manufacture an external combustion gas turbine which is, effectively, a turbine version of a hot air engine. Those systems are usually indicated as EFGT (Externally Fired Gas Turbine) or IFGT (Indirectly Fired Gas Turbine). External combustion has been used for the purpose of using pulverized coal or finely ground biomass (such as sawdust) as a fuel. In the indirect system, a heat exchanger is used and only clean air with no combustion products travels through the power turbine. The thermal efficiency is lower in the indirect type of external combustion; however, the turbine blades are not subjected to combustion products and much lower quality (and therefore cheaper) fuels are able to be used. When external combustion is used, it is possible to use exhaust air from the turbine as the primary combustion air. This effectively reduces global heat losses, although heat losses associated with the combustion exhaust remain inevitable. Closed-cycle gas turbines based on helium or supercritical carbon dioxide also hold promise for use with future high temperature solar and nuclear power generation.

In surface vehicles

Gas turbines are often used on ships, locomotives, helicopters,

s, and to a lesser extent, on cars, buses, and motorcycles. A key advantage of jets and

s for airplane propulsion – their superior performance at high altitude compared to piston engines, particularly naturally aspirated engine, naturally aspirated ones – is irrelevant in most automobile applications. Their power-to-weight advantage, though less critical than for aircraft, is still important. Gas turbines offer a high-powered engine in a very small and light package. However, they are not as responsive and efficient as small piston engines over the wide range of RPMs and powers needed in vehicle applications. In series hybrid vehicles, as the driving electric motors are mechanically detached from the electricity generating engine, the responsiveness, poor performance at low speed and low efficiency at low output problems are much less important. The turbine can be run at optimum speed for its power output, and batteries and ultracapacitors can supply power as needed, with the engine cycled on and off to run it only at high efficiency. The emergence of the continuously variable transmission may also alleviate the responsiveness problem. Turbines have historically been more expensive to produce than piston engines, though this is partly because piston engines have been mass-produced in huge quantities for decades, while small gas turbine engines are rarities; however, turbines are mass-produced in the closely related form of the

. The turbocharger is basically a compact and simple free shaft radial gas turbine which is driven by the piston engine's exhaust gas. The centripetal turbine wheel drives a centrifugal compressor wheel through a common rotating shaft. This wheel supercharges the engine air intake to a degree that can be controlled by means of a wastegate or by dynamically modifying the turbine housing's geometry (as in a variable geometry turbocharger). It mainly serves as a power recovery device which converts a great deal of otherwise wasted thermal and kinetic energy into engine boost. Turbo-compound engines (actually employed on some semi-trailer trucks) are fitted with blow down turbines which are similar in design and appearance to a turbocharger except for the turbine shaft being mechanically or hydraulically connected to the engine's crankshaft instead of to a centrifugal compressor, thus providing additional power instead of boost. While the turbocharger is a pressure turbine, a power recovery turbine is a velocity one.

Passenger road vehicles (cars, bikes, and buses)

A number of experiments have been conducted with gas turbine powered automobiles, the largest by Chrysler. More recently, there has been some interest in the use of turbine engines for hybrid electric cars. For instance, a consortium led by micro gas turbine company Bladon Jets has secured investment from the Technology Strategy Board to develop an Ultra Lightweight Range Extender (ULRE) for next-generation electric vehicles. The objective of the consortium, which includes luxury car maker Jaguar Land Rover and leading electrical machine company SR Drives, is to produce the world's first commercially viable – and environmentally friendly – gas turbine generator designed specifically for automotive applications.Bladon Jets And Jaguar Land Rover Win Funding For Gas Turbine Electric Vehicle Project
The common turbocharger for gasoline or diesel engines is also a turbine derivative.

Concept cars

The first serious investigation of using a gas turbine in cars was in 1946 when two engineers, Robert Kafka and Robert Engerstein of Carney Associates, a New York engineering firm, came up with the concept where a unique compact turbine engine design would provide power for a rear wheel drive car. After an article appeared in ''Popular Science'', there was no further work, beyond the paper stage. ;Early concepts (1950s/60s) In 1950, designer F.R. Bell and Chief Engineer Maurice Wilks from British car manufacturers Rover Company, Rover unveiled the first car powered with a gas turbine engine. The two-seater Rover JET1, JET1 had the engine positioned behind the seats, air intake grilles on either side of the car, and exhaust outlets on the top of the tail. During tests, the car reached top speeds of , at a turbine speed of 50,000 rpm. After being shown in the United Kingdom and the United States in 1950, JET1 was further developed, and was subjected to speed trials on the Jabbeke highway in Belgium in June 1952, where it exceeded . The car ran on petrol, kerosene, paraffin (kerosene) or Diesel fuel, diesel oil, but fuel consumption problems proved insurmountable for a production car. JET1 is on display at the London Science Museum (London), Science Museum. A French turbine-powered car, the SOCEMA-Grégoire, was displayed at the October 1952 Paris Auto Show. It was designed by the French engineer Jean-Albert Grégoire. FirebirdI

The first turbine-powered car built in the US was the General Motors Firebird, GM Firebird I which began evaluations in 1953. While photos of the Firebird I may suggest that the jet turbine's thrust propelled the car like an aircraft, the turbine actually drove the rear wheels. The Firebird I was never meant as a commercial passenger car and was built solely for testing & evaluation as well as public relation purposes. Additional Firebird concept cars, each powered by gas turbines, were developed for the 1953, 1956 and 1959 Motorama auto shows. The GM Research gas turbine engine also was fitted to a series of transit buses, starting with the Turbo-Cruiser I of 1953. ChryslerTurbineEngine01 crop1

Starting in 1954 with a modified Plymouth (automobile), Plymouth, the American car manufacturer Chrysler Corporation, Chrysler demonstrated several Chrysler Turbine engines, prototype gas turbine-powered cars from the early 1950s through the early 1980s. Chrysler built fifty Chrysler Turbine Cars in 1963 and conducted the only consumer trial of gas turbine-powered cars. Each of their turbines employed a unique rotating recuperator, referred to as a regenerator that increased efficiency. In 1954 Fiat unveiled a concept car with a turbine engine, called Fiat Turbina. This vehicle, looking like an aircraft with wheels, used a unique combination of both jet thrust and the engine driving the wheels. Speeds of were claimed. In the 1960s, Ford and GM also were developing gas turbine semi-trucks. Ford displayed the Big Red at the 1964 World's Fair. With the trailer, it was long, high, and painted crimson red. It contained the Ford-developed gas turbine engine, with output power and torque of and . The cab boasted a highway map of the continental U.S., a mini-kitchen, bathroom, and a TV for the co-driver. The fate of the truck was unknown for several decades, but it was rediscovered in early 2021 in private hands, having been restored to running order. The Chevrolet division of GM built the ''Turbo Titan'' series of concept trucks with turbine motors as analogs of the Firebird concepts, including Turbo Titan I (, shares GT-304 engine with Firebird II), Turbo Titan II (, shares GT-305 engine with Firebird III), and Chevrolet Turbo Titan III, Turbo Titan III (1965, GT-309 engine); in addition, the GM Bison gas turbine truck was shown at the 1964 World's Fair. ;Emissions and fuel economy (1970s/80s) As a result of the U.S. Clean Air Act (United States), Clean Air Act Amendments of 1970, research was funded into developing automotive gas turbine technology. Design concepts and vehicles were conducted by Chrysler, General Motors, Ford Motor Company, Ford (in collaboration with Garrett AiResearch, AiResearch), and American Motors (in conjunction with Williams International, Williams Research). Long-term tests were conducted to evaluate comparable cost efficiency. Several AMC Hornets were powered by a small Williams regenerative gas turbine weighing and producing at 4450 rpm. In 1982, General Motors used an Oldsmobile Delta 88 powered by a gas turbine using pulverised coal dust. This was considered for the United States and the western world to reduce dependence on 1980s oil glut, middle east oil at the time Toyota demonstrated several gas turbine powered concept cars, such as the Toyota Century GT45, Century gas turbine hybrid in 1975, the Toyota Sports 800#Sports 800 Gas Turbine Hybrid, Sports 800 Gas Turbine Hybrid in 1979 and the Toyota GTV, GTV in 1985. No production vehicles were made. The GT24 engine was exhibited in 1977 without a vehicle. ;Later development In the early 1990s, Volvo introduced the Volvo ECC which was a gas turbine powered hybrid electric vehicle. In 1993 General Motors introduced the first commercial gas turbine powered hybrid vehicle—as a limited production run of the General Motors EV-1#EV1 series hybrid, EV-1 series hybrid. A Williams International 40 kW turbine drove an alternator which powered the battery-electric powertrain. The turbine design included a recuperator. In 2006, GM went into the EcoJet concept car project with Jay Leno. At the 2010 Paris Motor Show Jaguar Cars, Jaguar demonstrated its Jaguar C-X75 concept car. This electrically powered supercar has a top speed of and can go from in 3.4 seconds. It uses Lithium-ion batteries to power four electric motors which combine to produce 780 bhp. It will travel on a single charge of the batteries, and uses a pair of Bladon Micro Gas Turbines to re-charge the batteries extending the range to .

Racing cars

The first race car (in concept only) fitted with a turbine was in 1955 by a US Air Force group as a hobby project with a turbine loaned them by Boeing and a race car owned by Firestone Tire & Rubber company. The first race car fitted with a turbine for the goal of actual racing was by Rover and the British Racing Motors, BRM Formula One team joined forces to produce the Rover-BRM, a gas turbine powered coupe, which entered the 1963 24 Hours of Le Mans, driven by Graham Hill and Richie Ginther. It averaged and had a top speed of . American Ray Heppenstall joined Howmet Corporation and McKee Engineering together to develop their own gas turbine sports car in 1968, the Howmet TX, which ran several American and European events, including two wins, and also participated in the 1968 24 Hours of Le Mans. The cars used Continental Motors Company, Continental gas turbines, which eventually set six Fédération Internationale de l'Automobile, FIA land speed records for turbine-powered cars. For open wheel racing, 1967's revolutionary STP-Paxton Turbocar fielded by racing and entrepreneurial legend Andy Granatelli and driven by Parnelli Jones nearly won the Indianapolis 500; the Pratt & Whitney PT6, Pratt & Whitney ST6B-62 powered turbine car was almost a lap ahead of the second place car when a gearbox bearing failed just three laps from the finish line. The next year the STP Lotus 56 turbine car won the Indianapolis 500 pole position even though new rules restricted the air intake dramatically. In 1971 Team Lotus principal Colin Chapman introduced the Lotus 56, Lotus 56B F1 car, powered by a Pratt & Whitney PT6, Pratt & Whitney STN 6/76 gas turbine. Chapman had a reputation of building radical championship-winning cars, but had to abandon the project because there were too many problems with turbo lag.

Buses

General Motors fitted the GM Whirlfire engine, GT-30x series of gas turbines (branded "Whirlfire") to several prototype buses in the 1950s and 1960s, including GM "old-look" transit bus#Turbo-Cruiser I, Turbo-Cruiser I (1953, GT-300); GM New Look bus#Variants based on the New Look, Turbo-Cruiser II (1964, GT-309); Turbo-Cruiser III (1968, GT-309); Rapid Transit Series, RTX (1968, GT-309); and Transbus Program, RTS 3T (1972). The arrival of the Capstone Turbine has led to several hybrid bus designs, starting with HEV-1 by AVS of Chattanooga, Tennessee in 1999, and closely followed by Ebus and ISE Research in California, and DesignLine Corporation in New Zealand (and later the United States). AVS turbine hybrids were plagued with reliability and quality control problems, resulting in liquidation of AVS in 2003. The most successful design by Designline is now operated in 5 cities in 6 countries, with over 30 buses in operation worldwide, and order for several hundred being delivered to Baltimore, and New York City. Brescia, Brescia Italy is using serial hybrid buses powered by microturbines on routes through the historical sections of the city.

Motorcycles

The MTT Turbine Superbike appeared in 2000 (hence the designation of Y2K Superbike by MTT) and is the first production motorcycle powered by a turbine engine – specifically, a Rolls-Royce Allison model 250 turboshaft engine, producing about 283 kW (380 bhp). Speed-tested to 365 km/h or 227 mph (according to some stories, the testing team ran out of road during the test), it holds the Guinness World Record for most powerful production motorcycle and most expensive production motorcycle, with a price tag of US$185,000.

Trains

Several locomotive classes have been powered by gas turbines, the most recent incarnation being Bombardier Transportation, Bombardier's JetTrain.

Tanks

The Third Reich German Army (Wehrmacht), ''Wehrmacht Heer'''s development division, the Heereswaffenamt (Army Ordnance Board), studied a number of gas turbine engine designs for use in tanks starting in mid-1944. The first gas turbine engine design intended for use in armored fighting vehicle propulsion, the BMW 003-based GT 101, was meant for installation in the Panther tank. The second use of a gas turbine in an armored fighting vehicle was in 1954 when a unit, PU2979, specifically developed for tanks by C. A. Parsons and Company, was installed and trialed in a British Conqueror tank. The Stridsvagn 103 was developed in the 1950s and was the first mass-produced main battle tank to use a turbine engine, the Boeing T50. Since then, gas turbine engines have been used as

s in some tanks and as main powerplants in Soviet/Russian T-80s and U.S. M1 Abrams tanks, among others. They are lighter and smaller than diesel engines at the same sustained power output but the models installed to date are less fuel efficient than the equivalent diesel, especially at idle, requiring more fuel to achieve the same combat range. Successive models of M1 have addressed this problem with battery packs or secondary generators to power the tank's systems while stationary, saving fuel by reducing the need to idle the main turbine. T-80s can mount three large external fuel drums to extend their range. Russia has stopped production of the T-80 in favor of the diesel-powered T-90 (based on the T-72), while Ukraine has developed the diesel-powered T-80UD and T-84 with nearly the power of the gas-turbine tank. The French Leclerc tank's diesel powerplant features the "Hyperbar" hybrid supercharging system, where the engine's turbocharger is completely replaced with a small gas turbine which also works as an assisted diesel exhaust turbocharger, enabling engine RPM-independent boost level control and a higher peak boost pressure to be reached (than with ordinary turbochargers). This system allows a smaller displacement and lighter engine to be used as the tank's power plant and effectively removes turbo lag. This special gas turbine/turbocharger can also work independently from the main engine as an ordinary APU. A turbine is theoretically more reliable and easier to maintain than a piston engine since it has a simpler construction with fewer moving parts, but in practice, turbine parts experience a higher wear rate due to their higher working speeds. The turbine blades are highly sensitive to dust and fine sand so that in desert operations air filters have to be fitted and changed several times daily. An improperly fitted filter, or a bullet or shell fragment that punctures the filter, can damage the engine. Piston engines (especially if turbocharged) also need well-maintained filters, but they are more resilient if the filter does fail. Like most modern diesel engines used in tanks, gas turbines are usually multi-fuel engines.

Marine applications

Naval

Gas turbines are used in many naval vessels, where they are valued for their high power-to-weight ratio and their ships' resulting acceleration and ability to get underway quickly. The first gas-turbine-powered naval vessel was the Royal Navy's Motor Gun Boat ''MGB 2009'' (formerly ''MGB 509'') converted in 1947. Metropolitan-Vickers fitted their Metropolitan-Vickers F.2, F2/3 jet engine with a power turbine. The Steam Gun Boat ''Grey Goose'' was converted to Rolls-Royce gas turbines in 1952 and operated as such from 1953. The Bold class patrol boat, Bold class Fast Patrol Boats ''Bold Pioneer'' and ''Bold Pathfinder'' built in 1953 were the first ships created specifically for gas turbine propulsion. The first large-scale, partially gas-turbine powered ships were the Royal Navy's Tribal-class frigate, Type 81 (Tribal class) frigates with combined steam and gas powerplants. The first, was commissioned in 1961. The German Navy launched the first in 1961 with 2

gas turbines in the world's first combined diesel and gas propulsion system. The Soviet Navy commissioned in 1962 the first of 25 with 4 gas turbines in Combined gas and gas propulsion system. Those vessels used 4 M8E gas turbines, which generated . Those ships were the first large ships in the world to be powered solely by gas turbines. Smetlivyy2003

The Danish Navy had 6 ''Søløven''-class torpedo boats (the export version of the British Brave class fast patrol boat) in service from 1965 to 1990, which had 3 Bristol Proteus (later RR Proteus) Marine Gas Turbines rated at combined, plus two General Motors Diesel engines, rated at , for better fuel economy at slower speeds. And they also produced 10 Willemoes Class Torpedo / Guided Missile boats (in service from 1974 to 2000) which had 3 Rolls-Royce plc, Rolls-Royce Marine Proteus Gas Turbines also rated at , same as the Søløven-class boats, and 2 General Motors Diesel Engines, rated at , also for improved fuel economy at slow speeds. The Swedish Navy produced 6 Spica-class torpedo boats between 1966 and 1967 powered by 3 Bristol Siddeley Bristol Proteus, Proteus 1282 turbines, each delivering . They were later joined by 12 upgraded Norrköping class ships, still with the same engines. With their aft torpedo tubes replaced by antishipping missiles they served as missile boats until the last was retired in 2005. The Finnish Navy commissioned two corvettes, ''Turunmaa'' and ''Karjala'', in 1968. They were equipped with one Rolls-Royce Olympus TM1 gas turbine and three Wärtsilä marine diesels for slower speeds. They were the fastest vessels in the Finnish Navy; they regularly achieved speeds of 35 knots, and 37.3 knots during sea trials. The ''Turunmaa''s were decommissioned in 2002. ''Karjala'' is today a museum ship in Turku, and ''Turunmaa'' serves as a floating machine shop and training ship for Satakunta Polytechnical College. The next series of major naval vessels were the four Canadian helicopter carrying destroyers first commissioned in 1972. They used 2 ft-4 main propulsion engines, 2 ft-12 cruise engines and 3 Solar Saturn 750 kW generators. USS Ford (FFG-54) Gas Turbine

The first U.S. gas-turbine powered ship was the United States Coast Guard, U.S. Coast Guard's , a cutter commissioned in 1961 that was powered by two turbines utilizing controllable-pitch propellers. The larger USCG high endurance cutter, High Endurance Cutters, was the first class of larger cutters to utilize gas turbines, the first of which () was commissioned in 1967. Since then, they have powered the United States Navy, U.S. Navy's s, and s, and guided missile cruisers. , a modified , is to be the Navy's first amphibious assault ship powered by gas turbines. The marine gas turbine operates in a more corrosive atmosphere due to the presence of sea salt in air and fuel and use of cheaper fuels.

Civilian maritime

Up to the late 1940s, much of the progress on marine gas turbines all over the world took place in design offices and engine builder's workshops and development work was led by the British Royal Navy and other Navies. While interest in the gas turbine for marine purposes, both naval and mercantile, continued to increase, the lack of availability of the results of operating experience on early gas turbine projects limited the number of new ventures on seagoing commercial vessels being embarked upon. In 1951, the Diesel-electric oil tanker ''Auris'', 12,290 deadweight tonnage (DWT) was used to obtain operating experience with a main propulsion gas turbine under service conditions at sea and so became the first ocean-going merchant ship to be powered by a gas turbine. Built by Hawthorn Leslie and Company, Hawthorn Leslie at Hebburn-on-Tyne, UK, in accordance with plans and specifications drawn up by the Anglo-Saxon Petroleum Company and launched on the UK's Elizabeth II, Princess Elizabeth's 21st birthday in 1947, the ship was designed with an engine room layout that would allow for the experimental use of heavy fuel in one of its high-speed engines, as well as the future substitution of one of its diesel engines by a gas turbine. The ''Auris'' operated commercially as a tanker for three-and-a-half years with a diesel-electric propulsion unit as originally commissioned, but in 1951 one of its four diesel engines – which were known as "Faith", "Hope", "Charity" and "Prudence" – was replaced by the world's first marine gas turbine engine, a open-cycle gas turbo-alternator built by British Thomson-Houston, British Thompson-Houston Company in Rugby, Warwickshire, Rugby. Following successful sea trials off the Northumbrian coast, the ''Auris'' set sail from Hebburn-on-Tyne in October 1951 bound for Port Arthur, Texas, Port Arthur in the US and then Curacao in the southern Caribbean returning to Avonmouth after 44 days at sea, successfully completing her historic trans-Atlantic crossing. During this time at sea the gas turbine burnt diesel fuel and operated without an involuntary stop or mechanical difficulty of any kind. She subsequently visited Swansea, Hull, Rotterdam, Oslo and Southampton covering a total of 13,211 nautical miles. The ''Auris'' then had all of its power plants replaced with a directly coupled gas turbine to become the first civilian ship to operate solely on gas turbine power. Despite the success of this early experimental voyage the gas turbine did not replace the diesel engine as the propulsion plant for large merchant ships. At constant cruising speeds the diesel engine simply had no peer in the vital area of fuel economy. The gas turbine did have more success in Royal Navy ships and the other naval fleets of the world where sudden and rapid changes of speed are required by warships in action. The United States Maritime Commission were looking for options to update WWII Liberty ships, and heavy-duty gas turbines were one of those selected. In 1956 the ''John Sergeant'' was lengthened and equipped with a

HD gas turbine with exhaust-gas regeneration, reduction gearing and a Variable-pitch propeller (marine), variable-pitch propeller. It operated for 9,700 hours using residual fuel (Bunker C) for 7,000 hours. Fuel efficiency was on a par with steam propulsion at per hour,Naval Education and Training Program Development Center ''Introduction to Marine Gas Turbines'' (1978) Naval Education and Training Support Command, pp. 3. and power output was higher than expected at due to the ambient temperature of the North Sea route being lower than the design temperature of the gas turbine. This gave the ship a speed capability of 18 knots, up from 11 knots with the original power plant, and well in excess of the 15 knot targeted. The ship made its first transatlantic crossing with an average speed of 16.8 knots, in spite of some rough weather along the way. Suitable Bunker C fuel was only available at limited ports because the quality of the fuel was of a critical nature. The fuel oil also had to be treated on board to reduce contaminants and this was a labor-intensive process that was not suitable for automation at the time. Ultimately, the variable-pitch propeller, which was of a new and untested design, ended the trial, as three consecutive annual inspections revealed stress-cracking. This did not reflect poorly on the marine-propulsion gas-turbine concept though, and the trial was a success overall. The success of this trial opened the way for more development by GE on the use of HD gas turbines for marine use with heavy fuels.National Research Council (U.S.) ''Innovation in the Maritime Industry'' (1979) Maritime Transportation Research Board, pp. 127–131 The ''John Sergeant'' was scrapped in 1972 at Portsmouth PA. 20091105-TurboJET Urzela

Boeing launched its first passenger-carrying Pump-jet, waterjet-propelled hydrofoil Boeing 929, in April 1974. Those ships were powered by two Allison 501-KF gas turbines. Between 1971 and 1981, Seatrain Lines operated a scheduled intermodal container, container service between ports on the eastern seaboard of the United States and ports in northwest Europe across the North Atlantic with four container ships of 26,000 tonnes DWT. Those ships were powered by twin Pratt & Whitney gas turbines of the FT 4 series. The four ships in the class were named ''Euroliner'', ''Eurofreighter'', ''Asialiner'' and ''Asiafreighter''. Following the dramatic Organization of the Petroleum Exporting Countries (OPEC) price increases of the mid-1970s, operations were constrained by rising fuel costs. Some modification of the engine systems on those ships was undertaken to permit the burning of a lower grade of fuel (i.e., Marine diesel oil, marine diesel). Reduction of fuel costs was successful using a different untested fuel in a marine gas turbine but maintenance costs increased with the fuel change. After 1981 the ships were sold and refitted with, what at the time, was more economical diesel-fueled engines but the increased engine size reduced cargo space. The first passenger ferry to use a gas turbine was the GTS Finnjet, GTS ''Finnjet'', built in 1977 and powered by two Pratt & Whitney FT 4C-1 DLF turbines, generating and propelling the ship to a speed of 31 knots. However, the Finnjet also illustrated the shortcomings of gas turbine propulsion in commercial craft, as high fuel prices made operating her unprofitable. After four years of service, additional diesel engines were installed on the ship to reduce running costs during the off-season. The Finnjet was also the first ship with a Combined diesel-electric and gas propulsion. Another example of commercial use of gas turbines in a passenger ship is Stena Line's High-speed Sea Service, HSS class fastcraft ferries. HSS 1500-class ''Stena Explorer'', ''Stena Voyager'' and ''Stena Discovery'' vessels use combined gas and gas setups of twin General Electric, GE General Electric LM2500, LM2500 plus GE LM1600 power for a total of . The slightly smaller HSS 900-class ''Stena Carisma'', uses twin Asea Brown Boveri, ABB–STAL GT35 turbines rated at gross. The ''Stena Discovery'' was withdrawn from service in 2007, another victim of too high fuel costs. In July 2000 the Millennium (ship), ''Millennium'' became the first cruise ship to be powered by both gas and steam turbines. The ship featured two General Electric LM2500 gas turbine generators whose exhaust heat was used to operate a steam turbine generator in a COGES (combined gas electric and steam) configuration. Propulsion was provided by two electrically driven Rolls-Royce Mermaid azimuth pods. The liner RMS Queen Mary 2 uses a combined diesel and gas configuration. In marine racing applications the 2010 C5000 Mystic catamaran Miss GEICO uses two Lycoming T-55 turbines for its power system.

Advances in technology

Gas turbine technology has steadily advanced since its inception and continues to evolve. Development is actively producing both smaller gas turbines and more powerful and efficient engines. Aiding in these advances are computer-based design (specifically computational fluid dynamics and finite element analysis) and the development of advanced materials: Base materials with superior high-temperature strength (e.g., single-crystal superalloys that exhibit yield strength anomaly) or thermal barrier coatings that protect the structural material from ever-higher temperatures. These advances allow higher compression ratios and turbine inlet temperatures, more efficient combustion and better cooling of engine parts. Computational fluid dynamics (CFD) has contributed to substantial improvements in the performance and efficiency of gas turbine engine components through enhanced understanding of the complex viscous flow and heat transfer phenomena involved. For this reason, CFD is one of the key computational tools used in design and development of gas turbine engines. The simple-cycle efficiencies of early gas turbines were practically doubled by incorporating inter-cooling, regeneration (or recuperation), and reheating. These improvements, of course, come at the expense of increased initial and operation costs, and they cannot be justified unless the decrease in fuel costs offsets the increase in other costs. The relatively low fuel prices, the general desire in the industry to minimize installation costs, and the tremendous increase in the simple-cycle efficiency to about 40 percent left little desire for opting for these modifications. On the emissions side, the challenge is to increase turbine inlet temperatures while at the same time reducing peak flame temperature in order to achieve lower NOx emissions and meet the latest emission regulations. In May 2011,

achieved a turbine inlet temperature of 1,600 °C on a 320 megawatt gas turbine, and 460 MW in gas turbine combined-cycle power generation applications in which gross thermal efficiency exceeds 60%. Compliant foil bearings were commercially introduced to gas turbines in the 1990s. These can withstand over a hundred thousand start/stop cycles and have eliminated the need for an oil system. The application of microelectronics and power switching technology have enabled the development of commercially viable electricity generation by microturbines for distribution and vehicle propulsion.

Advantages and disadvantages

The following are advantages and disadvantages of gas-turbine engines: Advantages include: * Very high power-to-weight ratio compared to reciprocating engines. * Smaller than most reciprocating engines of the same power rating. * Smooth rotation of the main shaft produces far less vibration than a reciprocating engine. * Fewer moving parts than reciprocating engines results in lower maintenance cost and higher reliability/availability over its service life. * Greater reliability, particularly in applications where sustained high power output is required. * Waste heat is dissipated almost entirely in the exhaust. This results in a high-temperature exhaust stream that is very usable for boiling water in a combined cycle, or for cogeneration. * Lower peak combustion pressures than reciprocating engines in general. * High shaft speeds in smaller "free turbine units", although larger gas turbines employed in power generation operate at synchronous speeds. * Low lubricating oil cost and consumption. * Can run on a wide variety of fuels. * Very low toxic emissions of CO and HC due to excess air, complete combustion and no "quench" of the flame on cold surfaces. Disadvantages include: * Core engine costs can be high due to use of exotic materials. * Less efficient than reciprocating engines at idle speed. * Longer startup than reciprocating engines. * Less responsive to changes in power demand compared with reciprocating engines. * Characteristic whine can be hard to suppress.

Major manufacturers

* Ansaldo * Mitsubishi Heavy Industries, Mitsubishi Heavy * Rolls-Royce Holdings, Rolls-Royce *

* Power Machines, Silmash * United Engine Corporation, ODK * Pratt & Whitney * Pratt & Whitney Canada, P&W Canada * Alstom * Zorya-Mashproekt * MTU Aero Engines * MAN Turbo * IHI Corporation * Kawasaki Heavy Industries, Kawasaki Heavy * Hindustan Aeronautics Limited, HAL * Bharat Heavy Electricals Limited, BHEL * MAPNA * Hanwha Techwin, Techwin * Doosan Heavy Industries & Construction, Doosan Heavy * Shanghai Electric * Harbin Electric * Aero Engine Corporation of China, AECC

Testing

British, German, other national and international test codes are used to standardize the procedures and definitions used to test gas turbines. Selection of the test code to be used is an agreement between the purchaser and the manufacturer, and has some significance to the design of the turbine and associated systems. In the United States, ASME has produced several performance test codes on gas turbines. This includes ASME PTC 22–2014. These ASME performance test codes have gained international recognition and acceptance for testing gas turbines. The single most important and differentiating characteristic of ASME performance test codes, including PTC 22, is that the test uncertainty of the measurement indicates the quality of the test and is not to be used as a commercial tolerance.

References

External links

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Technology Speed of Civil Jet Engines

*[http://travel.howstuffworks.com/turbine.htm Introduction to how a gas turbine works from "how stuff works.com"]
Aircraft gas turbine simulator for interactive learningAn online handbook on stationary gas turbine technologies compiled by the US DOE.
{{Authority control Gas turbines, Engines Marine propulsion