Gas turbine

Type of internal and continuous combustion engine

afterburning

turbofan

A gas turbine, gas turbine engine, or also known by its old name internal combustion turbine, is a type of continuous flow internal combustion engine.^[1] 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 combustor
• a compressor-driving turbine.

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) or ducted fan (turbofan) 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), marine propeller or electrical generator (power turbine). Greater thrust-to-weight ratio for flight is achieved with the addition of an afterburner.

The basic operation of the gas turbine is a

turbojet engine, 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 tanks.^[2]

Timeline of development

• 50: Earliest records of Hero's engine (aeolipile). 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.^[3]
• 1000: The "Trotting Horse Lamp" (
  Northern Song dynasty. 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.^[4]
• 1500: The
  Smoke jack was drawn by Leonardo da Vinci
  : 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.
• 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.^[5][6]
• 1894: Sir Charles Parsons patented the idea of propelling a ship with a steam turbine, and built a demonstration vessel, the Turbinia, easily the fastest vessel afloat at the time.
• 1899: Charles Gordon Curtis patented the first gas turbine engine in the US.^[7]
• 1900: Sanford Alexander Moss submitted a thesis on gas turbines. In 1903, Moss became an engineer for General Electric's Steam Turbine Department in Lynn, Massachusetts.^[8] While there, he applied some of his concepts in the development of the turbocharger.^[8]
• 1903: A Norwegian, Ægidius Elling, 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.^[9]
• 1904: A gas turbine engine designed by Franz Stolze, based on his earlier 1873 patent application, is built and tested in Berlin. The Stolze gas turbine was too inefficient to sustain its own operation.^[3]
• 1906: The
  Brown Boveri Company. The gas turbine could sustain its own air compression but was too inefficient to produce useful work.^[3]
• 1910: Holzwarth gas turbine (pulse combustion) achieved 150 kW (200 hp).^[3]
• 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.^[10]
• 1930: Having found no interest from the RAF for his idea, Frank Whittle patented^[11] the design for a centrifugal gas turbine for jet propulsion. The first successful test run of his engine occurred in England in April 1937.^[12]
• 1932: The
  Brown Boveri Company of Switzerland starts selling axial compressor and turbine turbosets as part of the turbocharged steam generating Velox boiler. Following the gas turbine principle, the steam evaporation tubes are arranged within the gas turbine combustion chamber; the first Velox plant was erected in Mondeville, Calvados, France.^[13]
• 1936: The first constant flow industrial gas turbine is commissioned by the Brown Boveri Company and goes into service at Sun Oil's Marcus Hook refinery in Pennsylvania, US.^[14]
• 1937: Working proof-of-concept prototype turbojet engine runs in UK (Frank Whittle's) and Germany (Hans von Ohain's Heinkel HeS 1). Henry Tizard secures UK government funding for further development of Power Jets engine.^[15]
• 1939: The First 4 MW utility power generation gas turbine is built by the Brown Boveri Company for an emergency power station in Neuchâtel, Switzerland.^[16] The turbojet powered Heinkel He 178, the world's first jet aircraft, makes its first flight.
• 1940: Jendrassik Cs-1, a turboprop engine, made its first bench run. It was designed by Hungarian engineer György Jendrassik, and was intended to power a Hungarian twin-engine heavy fighter, the RMI-1.^{[citation needed]}
• 1944: The Junkers Jumo 004 engine enters full production, powering the first German military jets such as the Messerschmitt Me 262. This marks the beginning of the reign of gas turbines in the sky.
• 1946: National Gas Turbine Establishment formed from Power Jets and the RAE turbine division to bring together Whittle and Hayne Constant's work.^[17] In Beznau, Switzerland the first commercial reheated/recuperated unit generating 27 MW was commissioned.^[18]
• 1947: A Metropolitan Vickers 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.^[19][20]
• 1995: Siemens becomes the first manufacturer of large electricity producing gas turbines to incorporate single crystal turbine blade technology into their production models, allowing higher operating temperatures and greater efficiency.^[21]
• 2011
  combined cycle gas turbine (the M501J) at its Takasago, Hyōgo, works.^[22][23]

Theory of operation

In an ideal gas turbine, gases undergo four

isentropic compression, an isobaric (constant pressure) combustion, an isentropic expansion and isobaric heat rejection. Together, these make up the Brayton cycle, also known as the "constant pressure cycle".^[24] It is distinguished from the Otto cycle, in that all the processes (compression, ignition combustion, exhaust), occur at the same time, continuously.^[24]

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 and the specific volume

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.

Air is taken in by a compressor, called a

air-fuel mixture, which then expands producing power across the turbine.^[24] This expansion of the mixture then leaves the combustor section and has its velocity increased across the turbine section to strike the turbine blades, spinning the disc they are attached to, thus creating useful power. Of the power produced, 60-70% is solely used to power the gas generator.^[24] The remaining power is used to power what the engine is being used for, typically an aviation application, being thrust in a turbojet, driving the fan of a turbofan, rotor or accessory of a turboshaft, and gear reduction and propeller of a turboprop.^[25][24]

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

turbojet engine

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 must double. For example, large jet engines operate around 10,000–25,000 rpm, while micro turbines spin as fast as 500,000 rpm.^[26]

Mechanically, gas turbines can be considerably less complex than Reciprocating 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 10,000 ℛℳ for materials, the Jumo 004 proved cheaper than the Junkers 213 piston engine, which was 35,000 ℛℳ,^[27] and needed only 375 hours of lower-skill labor to complete (including manufacture, assembly, and shipping), compared to 1,400 for the BMW 801.^[28] This, however, also translated into poor efficiency and reliability. More advanced gas turbines (such as those found in modern jet engines 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.^{[citation needed]} Since significant useful work can be generated by a relatively lightweight engine, gas turbines are perfectly suited for aircraft propulsion.

journal bearings are a critical part of a design. They are hydrodynamic oil bearings or oil-cooled rolling-element bearings. Foil bearings are used in some small machines such as micro turbines^[29] and also have strong potential for use in small gas turbines/auxiliary power units^[30]

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.^[31]

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

oxidation and corrosion resistance. Thermal barrier coatings (TBCs) are often stabilized zirconium dioxide-based ceramics and oxidation/corrosion resistant coatings (bond coats) typically consist of aluminides 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 200 °C (392 °F).^[32]

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.[33] 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.^[34]

Nickel-based superalloys boast improved strength and creep resistance due to their composition and resultant microstructure. The gamma (γ) FCC nickel is alloyed with aluminum and titanium in order to precipitate a uniform dispersion of the coherent Ni₃(Al,Ti) 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.^[35] Further Refractory elements such as rhenium and ruthenium 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.^[36] 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 and consequently deform by fewer modes – decreasing the creep rate.^[37] 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

high bypass, the difference being the amount of air moved by the fan, called "bypass air". These engines offer the benefit of more thrust without extra fuel consumption.^[24][25]

Gas turbines are also used in many

liquid-fuel rockets, where gas turbines are used to power a turbopump

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

Turboprop engines

A

Airbus A400M transport, Lockheed AC-130 and the 60-year-old Tupolev Tu-95 strategic bomber. While military turboprop engines can vary, in the civilian market there are two primary engines to be found: the Pratt & Whitney Canada PT6, a free-turbine turboshaft engine, and the Honeywell TPE331, a fixed turbine engine (formerly designated as the Garrett AiResearch

331).

Aeroderivative gas turbines

power plant

application

Aeroderivative gas turbines are generally based on existing aircraft gas turbine engines and are smaller and lighter than industrial gas turbines.[39]

Aeroderivatives are used in electrical power generation due to their ability to be shut down and handle load changes more quickly than industrial machines.^[40] They are also used in the marine industry to reduce weight. Common types include the General Electric LM2500, General Electric LM6000, and aeroderivative versions of the Pratt & Whitney PW4000 and Rolls-Royce RB211.^[39]

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.^[41][42] 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 as the core component. A combustion chamber is fabricated and plumbed between the compressor and turbine sections.^[43]

More sophisticated turbojets are also built, where their thrust and light weight are sufficient to power large model aircraft.^[44] The Schreckling design^[44] constructs the entire engine from raw materials, including the fabrication of a centrifugal compressor 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.^[45]

Auxiliary power units

Small gas turbines are used as auxiliary power units (APUs) to supply auxiliary power to larger, mobile, machines such as an aircraft, and are a turboshaft design.^[24] They supply:

• compressed air for air cycle machine style air conditioning and ventilation,
• compressed air start-up power for larger jet engines,
• 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

combined-cycle gas-fired power station in California, uses two GE 7F.04 combustion turbines to burn natural gas

.

thermodynamic efficiency is 62.22%

See also: Gas-fired power plant

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 configurations.

Gas turbines can be particularly efficient when

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

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.^[citation needed] 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 in aviation to power all but the smallest modern helicopters, and function as an auxiliary power unit in large commercial aircraft. 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.^[44] This engine can produce up to 22 newtons of thrust, and can be built by most mechanically minded people with basic engineering tools, such as a metal lathe.^[44]

Microturbines

Evolved from piston engine

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

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, tanks, and to a lesser extent, on cars, buses, and motorcycles.

A key advantage of jets and turboprops for airplane propulsion – their superior performance at high altitude compared to piston engines, particularly 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

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 turbocharger.

The turbocharger is basically a compact and simple free shaft radial gas turbine which is driven by the piston engine's

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.^{[citation needed]}

Passenger road vehicles (cars, bikes, and buses)

A number of experiments have been conducted with gas turbine powered

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.^[55]

Early concepts (1950s/60s)

In 1950, designer F.R. Bell and Chief Engineer

A French turbine-powered car, the SOCEMA-Grégoire, was displayed at the October 1952

The first turbine-powered car built in the US was the

Starting in 1954 with a modified

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 282 km/h (175 mph) were claimed.^[62]

In the 1960s, Ford and GM also were developing gas turbine semi-trucks. Ford displayed the Big Red at the

In the early 1990s, Volvo introduced the Volvo ECC which was a gas turbine powered hybrid electric vehicle.^[76]

In 1993 General Motors developed a gas turbine powered EV1 series hybrid—as a prototype of the General Motors EV1. 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 demonstrated its Jaguar C-X75 concept car. This electrically powered supercar has a top speed of 204 mph (328 km/h) and can go from 0 to 62 mph (0 to 100 km/h) in 3.4 seconds. It uses Lithium-ion batteries to power four electric motors which combine to produce 780 bhp. It will travel 68 miles (109 km) 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 560 miles (900 km).^[77]

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.^[78] The first race car fitted with a turbine for the goal of actual racing was by Rover and the 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 107.8 mph (173.5 km/h) and had a top speed of 142 mph (229 km/h). 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 gas turbines, which eventually set six FIA land speed records for turbine-powered cars.^[79]

For

Buses

General Motors fitted the GT-30x series of gas turbines (branded "Whirlfire") to several prototype buses in the 1950s and 1960s, including Turbo-Cruiser I (1953, GT-300); Turbo-Cruiser II (1964, GT-309); Turbo-Cruiser III (1968, GT-309); RTX (1968, GT-309); and RTS 3T (1972).^[80]

The arrival of the

Brescia Italy is using serial hybrid buses powered by microturbines on routes through the historical sections of the city.^[81]

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's JetTrain.

Tanks

The Third Reich

Naval

Gas turbines are used in many

The first large-scale, partially gas-turbine powered ships were the Royal Navy's Type 81 (Tribal class) frigates with combined steam and gas powerplants. The first, HMS Ashanti was commissioned in 1961.

The German Navy launched the first Köln-class frigate in 1961 with 2 Brown, Boveri & Cie gas turbines in the world's first combined diesel and gas propulsion system.

The Soviet Navy commissioned in 1962 the first of 25 Kashin-class destroyer with 4 gas turbines in combined gas and gas propulsion system. Those vessels used 4 M8E gas turbines, which generated 54,000–72,000 kW (72,000–96,000 hp). Those ships were the first large ships in the world to be powered solely by gas turbines.

The

The Swedish Navy produced 6 Spica-class torpedo boats between 1966 and 1967 powered by 3 Bristol Siddeley Proteus 1282 turbines, each delivering 3,210 kW (4,300 shp). 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.^[89]

The Finnish Navy commissioned two Turunmaa-class corvettes, Turunmaa and Karjala, in 1968. They were equipped with one 16,410 kW (22,000 shp) 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 Turunmaas 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 Iroquois-class 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.

The first U.S. gas-turbine powered ship was the

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

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.[92]

The

In marine racing applications the 2010 C5000 Mystic catamaran Miss GEICO uses two Lycoming T-55 turbines for its power system.^{[citation needed]}

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 (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^[97][98] 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.^[99]

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,

Advantages and disadvantages

This section contains a pro and con list. Please help rewriting it into consolidated sections based on topics. (June 2022)

The following are advantages and disadvantages of gas-turbine engines:[103]

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.

• Siemens Energy
• Ansaldo
• Mitsubishi Heavy Industries
• Rolls-Royce
• General Electric
• Silmash
• ODK
• Pratt & Whitney
• P&W Canada
• Solar Turbines
• Alstom
• Zorya-Mashproekt
• MTU Aero Engines
• MAN Turbo
• IHI Corporation
• Kawasaki Heavy Industries
• HAL
• BHEL
• MAPNA
• Techwin
• Doosan Heavy
• Shanghai Electric
• Harbin Electric
• 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,

See also

• List of aircraft engines
• Centrifugal compressor
• Gas turbine modular helium reactor
• Pneumatic motor
• Pulsejet
• Steam turbine
• Turbine engine failure
• Wind turbine

References

Further reading

• Stationary Combustion Gas Turbines including Oil & Over-Speed Control System description
• "Aircraft Gas Turbine Technology" by Irwin E. Treager, McGraw-Hill, Glencoe Division, 1979,
  ISBN 0-07-065158-2
  .
• "Gas Turbine Theory" by H.I.H. Saravanamuttoo, G.F.C. Rogers and H. Cohen, Pearson Education, 2001, 5th ed.,
  ISBN 0-13-015847-X
  .
• Leyes II, Richard A.; Fleming, William A. (1999). The History of North American Small Gas Turbine Aircraft Engines. Washington, DC: Smithsonian Institution.
  ISBN 978-1-56347-332-6
  .
• R. M. "Fred" Klaass and Christopher DellaCorte, "The Quest for Oil-Free Gas Turbine Engines," SAE Technical Papers, No. 2006-01-3055, available at sae.org
• "Model Jet Engines" by Thomas Kamps
  ISBN 0-9510589-9-1
  Traplet Publications
• Aircraft Engines and Gas Turbines, Second Edition by Jack L. Kerrebrock, The MIT Press, 1992,
  ISBN 0-262-11162-4
  .
• "Forensic Investigation of a Gas Turbine Event" by John Molloy, M&M Engineering
• "Gas Turbine Performance, 2nd Edition" by Philip Walsh and Paul Fletcher, Wiley-Blackwell, 2004
  ISBN 978-0-632-06434-2
• Advanced Technologies for Gas Turbines (Report). Washington, DC: The National Academies Press. 2020.
  ISBN 978-0-309-66422-6
  .

External links

Wikimedia Commons has media related to Gas turbines.

• Gas turbine at
  Curlie
• Armagnac, Alden P. (December 1939). "New Era In Power To Turn Wheels". Popular Science. p. 81.
• Technology Speed of Civil Jet Engines
• MIT Gas Turbine Laboratory Archived 21 July 2010 at the Wayback Machine
• MIT Microturbine research
• California Distributed Energy Resource guide – Microturbine generators
• Introduction to how a gas turbine works from "how stuff works.com" Archived 16 June 2008 at the Wayback Machine
• Aircraft gas turbine simulator for interactive learning
• An online handbook on stationary gas turbine technologies compiled by the US DOE. Archived 1 July 2017 at the Wayback Machine