Jet engine

of these articles is occupied with air-breathing jet engines. For other meanings, see jet engine (term clarifying).

A jet engine (also jet engine or turbo-jet engine, English. Turbojet and/or. Turbofan) is an engine, which works according to the principle of the recoil drive. Carrier of the thrust is thereby a gas jet. Jet engines suck in the ambient air and push them as drive jet. Because the oxygen necessary for the burn is taken from sucked in air, one speaks also of air-breathing engines.

Jet engine is today of outstanding importance for commercial air traffic. Over 99% of the transportations of airplanes with jet engines are furnished. Outside of aviation they are not no more used against it, after earlier attempts, today.

function mode

of thrust portions as well as speed, temperature and pressure processes in a jet engine.

A jet engine is nearly always in the today's form a turbine jet engine. This aspirates the environment air and compresses it in a compressor (increase in pressure). In the following combustion chamber the fuel is injected and this mixture is then burned. The burn (=Expansion) increases the temperature andthe flow rate whereby the static pressure of the gas easily drops. Those the gas supplied Störumgs energy is then unloaded in the turbine following behind it and converted in rotating motion, whereby the gas continues to expand partial. The turbine serves as drive of the compressor, the fan and other oneAggregates like e.g. the generator and the hydraulic pumps. Depending upon design of the engine e.g. with the wave achievement engine the gas energy is taken up and converted nearly completely by the turbine. The gas expands into the thrust nozzle behind the turbine on nearly ambient pressure, whereby the flow rate furtherone increases. In the thrust nozzle the actual Vortriebskraft (thrust) is produced by the leaking out gas. With the many in the military and supersound - range working jet engines is appropriate behind the turbine for increase in output still another afterburner.

This process can quite compared with in a piston motorbecomes, whereby however all four clocks - sucking in, consolidating, burning and discharging - at the same time and continuously to take place. Kraft resulting from it according to Newton's reaction principle is the thrust. The advantage of the jet propulsion in relation to the drive over a piston motor is in its efficiency at high speeds(particularly with supersonic speed) in large heights and in its high power density.

A simple jet engine accelerates a relatively small mass air very strongly, against what a propeller accelerates a large air mass by far more weakly.

The highly exact manufacturing expenditure and associated high procurement costs are unfavorable. This closesthese drives of the market of the sport and hobby airplanes out. Turbine jet engines are sensitive compared with piston motor/propeller combinations opposite foreign bodies. Already a increased dust load can shorten the Wartungsintervalle drastically. The penetration of water is however unproblematic.

Starting the engine takes place, by the compressor on a minimum number of revolutionsone brings. This can take place via injecting air, electrically, by means of a separate turbine with reduction gears (air starter/cartouche starter) or via a small combustion engine. Generally today an electrical starter for smaller engines is used, all commercial engines the airbus or Boeing airplanespossess air starters. Boeing goes however with Boeing 787 the way using a Elektrostarter also with large engines (GE nx one). This is a further step to the new concept “Electric engine”.

After reaching the minimum number of revolutions fuel is injected into the combustion chamber and by one orseveral spark plugs ignited. After the inflammation of the fuel and further number of revolutions increase the ignition is switched off; the burn continues to run off continuously. The number of revolutions range of control between no-load operation and full load amounts to thereby up to 95%, usually however only about 40%. The performance curve runs asall turbomachines in approximately logarithmic, with approximately 90% number of revolutions become approx. 50% of the achievement made available, at 100% number of revolutions are then made available to 100% achievement.

So-called bleed air is removed from the compressor, with which the pressurized cabin is supplied.

physical fundamentals

loss-loose joule process.

Propulsion efficiency in dependencethe airspeed.

For the efficiency - computation of a jet engine is suitable the joule process best. Crucial process parameters are at it the pressure and temperature differences. Ideal way is consolidated thus highly, one selects as high a turbine inlet temperature as possible T _{3 and leaves then the work gas over as large a nozzle as possibleexpand on as small a temperature as possible.}

thrust formula and propulsion efficiency

the thrust produced by the engine correspond, in case of a constant airspeed and a constant flight altitude, to the air resistance of the airplane; the thrust must be larger than the resistance, if accelerate or rise the airplaneis.

It applies the following simplified thrust formula on neglected amount of fuel and the assumption that the withdrawal pressure of the incineration gases corresponds to the ambient pressure:

<math> S= \ DOT m_l (c_5 - c_0)< /math>.

S thrust in N

< math> \ DOT m_l< /math> Air mass stream in kg/s

< math> c_5< /math> Gas exhaust velocity opposite the missile in m/s

< math> c_0< /math> airspeed in m/s

forthe propulsion efficiency applies however

< math> \ eta_v= \ frac {2 c_0} {c_0 + c_5} </math>.

Therefore today in the civil aviation bypassing rubbing works with high bypass ratio are used, with which a large air mass stream leaves relatively slowly the engine, what a better efficiency and not least also a noise reduction caused.

Jet engine types

gas turbine

structure in principle of a flight gas turbine

flight gas turbines possess intakes, compressor, combustion chamber, turbine and nozzle. Up to intakes and nozzle all other components over or also several waves are coupled. The intake arranged in front is at high speedsof use, since air mass flowing in is compressed already there.

compressors/compressor

CAD - design of a turbofan engine within the range of the compressor.

After the air intake the compressor complex follows, which from several impellers with compressor shovels in axial designexists. It has the task to supply to air mass flowing in kinetic energy and convert these into pressure energy. This happens in the diffusorförmigen (i.e. itself extending) gaps of the compressor shovels. After the law of Bernoulli the static pressure increases in a channel increasing in cross-section area, while thoseFlow rate sinks. The kinetic energy lost now becomes again balanced in a stator wheel. A complete compressor stage of an axial compressor consists thus of a stator wheel, in which both pressure and temperature and the speed rise, and a stator disc, in that the pressure to Ungunsten of the speedrises. The stator wheels are one behind the other on a common drum (today: two to three drums) arranged, the stator discs are firmly into the inside of the compressor stator inserted.

Old compressors with 17 following each other compressor stages reach only a compression of 12,5:1 (pressure at the end of the compressor: Ambient pressure), duringmodern engines with fewer stages substantially higher compressions obtain (43,9: 1 with 13 stages). This is possible by improved profiles of the compressor shovels, which offer very good flow characteristics even with supersonic speeds (resulting from peripheral speed of the shovels and incident-flow velocity). The pure flowing through speed may not do however the local speed of soundexceed, since otherwise the effect of the diffusorförmigen channels would turn around. Here it applies to consider that the local speed of sound because of the rising temperature in the compressor (s.o. until 600°C) likewise rises.

CAD design: Combustion chamber of a turbofan engine.

combustion chamber

the highCompression of air causes a strong temperature rise. Air in such a way heated up flows afterwards into the combustion chamber, where its fuel is supplied. This is ignited with the engine start by spark plugs. Subsequently, the burn takes place continuously. By the exotherms reaction oxygen - hydrocarbon - of the mixture comes itto a renewed temperature rise and an expansion of the gas. This section of the engine is by temperatures of up to 2500K (approx. 2200 °C) strongly loads. Without cooling also the high-quality materials (often nickel - basis alloys) could not withstand these temperatures, because the combustion chamber works in the supercriticalRange. Therefore the direct contact between the flame and the shroud is prevented. This is done via the so-called. „Sekundärluft “, which does not arrive directly into the burn range, is led, but around the combustion chamber and only then, by drillings at the plate joints of the shed-like developed combustion chamber, inthis arrives and as film between the incineration gases and the combustion chamber wall puts. This is called film cooling. Approximately 70 - 80% of entire air mass from the compressor are used as Sekundärluft, only the remainder arrived as primary air directly into the combustion chamber. Thus the flamedoes not expire, are the Einspritzventile for the fuel in a protected zone (in a lee of flowing through air). Further in direct environment the air flow speed is reduced (approx. 25-30 m/s), in order to prevent an expiring of the flame and to obtain an optimal burn. The combustion chamberdetermined by its interpretation the pollutant content in the exhaust gas. One differentiates thereby between tube-type combustion chambers, cannular combustion chambers and annular combustion chambers.

tube-type combustion chamber

this kind of the combustion chamber is particularly suitable for engines with radial compressor, as it uses in particular at the beginning of the development in Great Britain and today with turbo-propane impulsesbecomes. This is because of the individual diffusers of the radial compressor, which already divides the air flow. Each combustion chamber possesses its own primary and secondary air system. The combustion chambers are connected by the ignition bars. Generally about 8-12 of these tube-type combustion chambers is arranged radially at the engine. Very small turbines, aboutfor APUs, possess only an individual tube-type combustion chamber. The disadvantage of the high Konstruktionsgewichts of such an arrangement faces the advantage of the simple development, simple fuel distribution and good maintenance possibilities. Also the flow conditions are unfavorable in relation to other combustion chamber designs.

the tubing combines cannular combustion chambers this combustion chamber designand the annular combustion chamber and is particularly suitable for very large and high performance gas turbines, because it can be trained mechanically very stably. Substantial difference to the single combustion chamber is the common combustion chamber withdrawal. The design hardly occurs with turbo-jet engine drives.

the gas dynamics places annular combustion chambers the annular combustion chamber arrangementOptimum for turbo-jet engine engines. It is quite thereby easy and can be built briefly, since from the compressor to the turbine no detours must take place. The combustion chamber has a number of fuel injecting valves, which deliver the fuel to a circular combustion chamber. However maintenance is quite difficult.Also the development is very aufwändig, since the gas flows must be computed within such a combustion chamber three-dimensional. The annular combustion chamber is today the common type with aviation jet engines.

CAD design: Turbine of a turbofan engine: The high pressure turbine propels the compressor, the low-pressure turbine over a coaxial wave the fan.

turbine

the gases withdrawing to the rear meet afterwards a turbine. This propels the compressor over a wave. With most single-flow engines the largest part of the kinetic energy for the recoil is used. It becomes thustransfer only so much energy to the turbine, as is used for the enterprise of the compressor. Today usually two or three speed turbines are used, which propel a part of the likewise multi-level compressor by in each case a wave.

The turbine blades are normally cooled (interior or film cooling) andconsist today of resistant superalloys. These materials will beyond that solidified in a preferred direction, received in their crystal lattice thus a defined direction and thus permit to let the optimal material properties become effective along the highest load. About that becomes additional in particularly critical places,Shovel front edge, the material with ceramic linings protected. Because of the high load a break is not to be excluded nevertheless, therefore the coats are laid mats out by turbines with kevlar -, in order to prevent that engine parts damage basic structures or hurt persons.

thrust nozzle

behind the turbinea convergent nozzle is attached, by which the gas with high speed leaks out and thus the thrust produced, why this nozzle thrust nozzle is called. At the turbine exit existing pressure gradients (turbine initial pressure - ambient pressure) thereby completely in speed one converts. Here it is if possible the goal, oneto reach high flow-out rate, whereby the pressure of the leaking out gas at the thrust nozzle end is to have reached the ambient pressure at the same time, so that the gas jet does not burst.

Engines with afterburner expand not completely, but again supply to the remaining gas flow with existing positive pressure (to the ambient pressure) in the afterburner fuel, whichto a further acceleration of the gas flow leads. Thus can be corresponded to a fast thrust requirement, how it is necessary for instance in the maneuver flight. Engines with afterburner have usually a nozzle (Nozzle), variable in their geometry, in order to always achieve the optimal efficiency.

parameters

a turbine jet engine possess a multiplicity of characteristics. Here a list of the most important technical parameters, in order to be able to manufacture a fast comparison of different jet engines:

• Kind of the compressor (radial/axial/combination/separate)
• kind of the turbine (radial/axial/combination/separate)
• kind of the combustion chambers
• number of fan stages
• number of low pressure compressor stages
• amount of thatHigh pressure compressor stages
• number of high pressure turbines
• number of low-pressure turbines
• number of waves
• air volume (kg/s)
• engine length
• engine diameter
• dry weight
• thrust
• bypass ratio
• compression of the compressor
• specific fuel consumption (kg/kNh)

turbojet engine

the turbojet is the simplest form of a jet engine. It consists of a gas turbine,with that the exhaust gas as means of driving is used. The engine has usually only one wave, on which compressors and turbine are coupled with one another. The complete gas throughput runs by the combustion chambers. By its high exhaust velocities it has a small efficiency at low speeds,developed however a high noise level. Straight one with subsonic speed is the specific fuel consumption high and represents an intolerable environmental impact. Single flow jet engines do not belong therefore nowadays any longer to the equipment of airplanes. They form the simplest form of a wave jet engine. The engine is quite compact and maintenancesimply. Their assignment lay particularly in the years after the Second World War to center of the 1960er years, both in the civilian as well as in military air traffic, whereby the turbojet could keep itself longer in military application.

two-current jet engine (turbofan) (turbofan)

Major item: Turbofan

this kind of engine is the today common form of the jet engine. Practically all today with turbo-jet engines of manufactured airplanes are equipped with turbofans.

Turbofan engines are characterised thereby by at least two coaxial waves and an increased first compressor stage, those from their own turbine stageone propels. Behind it the air flow divides on into an internal air flow, which arrive into the actual gas turbine, and an outside air flow, which are led past outside the turbine. Outstinging technical characteristic of a turbofan is the bypass ratio, thus the relationship of the amount of air, thoseoutside by the fan flows, to the amount of air, which flows by the gas turbine.

A turbofan offers several advantages opposite a turbojet:

• Better efficiency of the engine by the smaller medium speed of the drive air jet and thus smaller fuel consumption.
• Reduction of the noise generation, by are called, quick andthus turbine gases read by the surrounding cool and calmer gas flow of the first stage to be absorbed.

Today's fighters use, so that air resistance becomes not too high by a large engine diameter and thus according to large fuselage cross-section with the supersonic flight, turbofan engines with relatively low bypass ratio, thus the amount of air,around the combustion chamber one leads, relative to the amount of air, which by the combustion chambers is led, (to approximately 1.5) and an only small noise reduction opposite turbojet engines. In the civilian range and with transportation machines engines with a bypass ratio to approximately 9 are in the use.

Propeller type turbine (turbo-prop.)

operation diagramme of a turbo-prop (A propeller, B transmission, C compressor, D combustion chamber, E turbine, F output nozzle).

Major item: Turbo-prop.

a special form is the drive of a propeller (propeller) by a turbine. This drive system is called turbo-prop. The gas turbine has for this at least two waves.The propeller is propelled by a reduction gear of the drive turbine. First turbo-props developed already for end of the 1940er years on basis of turbojet engines. In particular in the short-distance traffic and with middle flight altitudes the turbo-propane impulse is the most economical aircraft propulsion. Also the noise pollution is relatively small, there the exhaust gas jet by thoseDrive turbine is strongly calmed down. The exhaust gas stream contributes thereby only in relatively small measure to the propulsion, is however nevertheless in the achievement calculation during the wave comparison achievement contained. Opposite piston engines the propeller type turbine is characterised by high power density and long Wartungsintervalle . A comparable kind of turbine also gets Helicopters to the employment.

ram-jet engine

major item: Ram-jet engine

With ram-jet engines the compression that takes place the combustion chamber supplied air not via mechanically propelled mobile parts (thus axial or radial compressors), but throughUtilization of the stagnation pressure. Ram-jet engines are characterised by greatest possible simplicity, since they need nearly no mobile parts. The large disadvantage is that they are not able to produce a static thrust. Before a ram-jet engine delivers thrust, it must be accelerated. Within the groupthe ram-jet engines can one still between RAM jet - and Scramjet (Supersonic Combustion RAM jet) - engines differentiate. With the latter air flowing in keeps supersonic speed (supersonic combustion also after the compression and in the combustion chamber - Supersonic Combustion).

While the principle was already patented before the First World War, it lastedmore than 30 years, until the first ram-jet engine ran. In the Second World War the development of this technology was advanced in Germany, an attempt copy was already tested at a Dornier DO 217 in the flight. Into the 1950er years appropriate attempts were accomplished in particular in France. The attemptsnorth aviation N 1500 Griffon culminated, in the long run failed them however because of the ram-jet engine which can not be adapted in the testbed. Ram-jet engines are used today with long-range and supersonic unmanned missiles. They compete thereby with the rocket engines.

With a Scramjet drive the X-43A was operated, by that NASA developed hypersonic airplane. To 16. November 2004 reached the missile thereby for 10 seconds scarcely 10 times speed of sound, which represents the highest ever speed reached with an air-breathing engine.

pulse or Verpuffungsstrahltriebwerk

major item: Verpuffungsstrahltriebwerk

pulse or Verpuffungsstrahltriebwerke are compared with power plantsto manufacture likewise relatively simply. In contrast to other jet engines the burn runs periodically. The most common engines possess a flap device (flutter valve) for Luftregulierung, a combustion chamber and a relaxation zone, in which the hot gases can calm down.

As is the case for a ram-jet engine air flowsindependently into the engine. The flutter valves open and leave air into the combustion chamber influxes. Afterwards the aerodynamic force material mixture is ignited by a spark plug. By the expansion and the pressure resulting from it close the flutter valves, the incineration gases can only to the rear escape and producethe propulsion. After the gas left the engine, it comes to a relaxation and to renewed opening of the flutter valves. Thus fresh air can flow, which is again ignited by a pressure surge. This expiration repeats itself periodically. The system represents a Helmholtz-Resonator. ThisBuilding method supplies also while stationary thrust.

As is the case for the ram-jet engines also the spectrum of use of the pulse jet engines is limited. Most well-known representative of this engine technology in 2. World war was the Argus As 014 - engine of the Fieseler Fi 103 (better well-known than “retaliation weapon V1”). It came also with the MesserschmittME 328 B, prototypes for an interceptor from the year 1943, to the employment.

Nowadays the Verpuffungsstrahltriebwerk in aviation is not no more used. Among the disadvantages, those rank the enormous volume (with a sound pressure up to 140 railways) by the periodic ignitionsdevelops, which relatively small thrust in relation to the used up fuel as well as the enormous heating up of the engine (~1.000°C). Only in reduced yardstick it is still used with model airplanes.

maximum

700

km/h reached history [work on] of beginnings of propeller-driven aircraft, throughadjustable propellers and different techniques for the increase in output of the engines to be still slightly increased could. However the goal did not leave itself of building airplanes which could fly faster than 800 km/h, to realize, without developing a new propulsion technology. Those already early as the best solution of recognized recoil drivescould be converted only, when one sufficient knowledge in the areas of the aerodynamics, which thermodynamics as well as the metallurgy had.

The first independently running gas turbine already developed the Norwegian Aegidius Elling in the year 1903. Victor de Karavodine developed then in the year 1906 the bases of theVerpuffungsstrahltriebwerks.Georges Marconnet suggested this kind of engine in the year 1909 as jet engine for applications of aviation. Despite everything the power plant became the first design, which, beside rockets, propelled an airplane.

A Nebenlinie for the production of a jet engine were hybrid Designs, with those the compression by an external energy sourcetook place. In such a system (thermal jet of Secondo Campini) air was mixed by a blower, which was propelled by a conventional petrol engine, with the fuel and burned then for thrust production. There were three copies of this design, Henri Coandas Coanda-1910,the Campini Caproni CC.2 and the Japanese Tsu-11 - drive , which for the Ohka Kamikaze -, developed many later, airplanes toward end of the Second World War was intended. None of these drives was successful, the CC.2 turned out finally more slowly than a conventional airplane with the same engine.

engine development of franc Whittle

franc Whittle

franc Whittle submitted already 1928 different suggestions on the building of jet engines. It thought of a drive system, which should perform its work at a value of 35.000 m, could however no partners win.

The key tooa usable jet propulsion was the gas turbine, with which the energy came for the drive of the compressor from the turbine. The work on such a integrated design began in England 1930. Whittle submitted appropriate patents for such a drive, which were recognized 1932.Its engine possessed only one turbine stage, which propelled a centrifugal compressor.

1935 created Rolf Dudley Williams the company Power jet Ltd. and Whittle began as a development boss. Whittle designed an engine, the type U, its first test run to 12. April 1937 and good results taken place showed.The war Ministry placed thereupon money for the order, and it began the development of the aviation-suited type W.1. The company Gloster aircraft was assigned to manufacture a suitable airplane. Thus originated in for the first time to 15. May 1941 flown experimental aircraft E 28/39.

engine development ofHans's von Ohain

independent of Whittles work 1935 began Hans's von Ohain in Germany its work on a similar engine. Ohain contacted Ernst Heinkel, who recognized the advantages of the new propulsion principle immediately. Ohain formed a new together with its mechanic master max cockDepartment within the company Heinkel.

The first drive - Heinkel HeS 1 - was running 1937. Differently than Whittle Ohain used first hydrogen than fuel, on which he also led back its rapid successes. The following drafts found their high point in the Heinkel HeS 3 with 550 kp (approx. 5,4 kN), which was built into the Heinkel He 178 particularly for this designed. To impressing a short development time this prototype already flew in August 1939 as the first jet of the world. When first jet engine in series became later the Jumo 004 starting from 1942 produced,which was used among other things into the twin-jet Messerschmitt ME 262. To end of war about 5,000 units of this engine were produced.

military development during 2. World war

The German engines were throughout equipped with an axial compressor and had so a smaller diameter than the English radial compressors. The main lines of development were BMW 003 and the Junkers Jumo 004

priority of the German line of development had the increase of the speed; Fuel consumption, weight and stability should be improved in the course of the development. After 1941 it, a new achievement output of 800 kp applied (approx. to reach 7,8 kN). One used soon no more regular grade fuels, but Diesel fuel, the lighter to procure was and a higher Boiling point has. One needed now however a modified ignition system.

Up to the end of the war about 6,300 engines of the types BMW-003 and Jumo 004 were manufactured, which further improvements reached with the achievement, later with approximately 900 kp (approx. kN) was appropriate for 8,8. The Heinkel engine HeS11 ran with end of war with 1300 kp (approx. 12,7 kN) and were the strongest turbojet engine of the world. With BMW and Heinkel also the first propeller type turbines were in the development.

on the basis of the W.1 was developed in Great Britain the engine Rolls-Royce waving and,that about 7,56 kN thrust delivered. This engine was used at first in the Gloster meteor. Far uprated variant was the Rolls-Royces Derwent, which likewise in the meteor found use. These two engines were the only one on British side, which were used for combat aircraft.On this concept - radial compressors, tube-type combustion chamber and axial-flow turbine - the entire line of development of the British jet engine technology up to the beginning of the 1950er was based years.

First operational American jet engine was the General Electric J31 likewise, over a radial compressor and an axial-flow turbine ordered and in that Bell P-59 to the employment came. The substantially more efficient Allison J33 was based on de Havilland the Goblin. It was used in the Lockheed P-80 and came for the employment into 2. World war in fact too late.

In the Soviet Union and in Japan found during of the2. World war no substantial developments at jet engines instead of.

military advancement

The compiled knowledge formed with the basis for further developments in the military alliances Warsaw Pact andin NATO. A goal of the developments was first the increase in output, without the size had to be changed. That led fast to the development of the afterburner engines, which brought a substantial increase in output with a small additional weight. This was obtained however at expense of the fuel consumption. Typical one Representatives into the 1950er years were in the west the General Electric J79, in the east the Tumanski R-11. Both engines made the raid into speed ranges to Mach for 2 possible. The technical problems were as far as possible solved. Only the raid toward Mach 3 center of the 1960erAn advancement demanded years. In the Soviet Union the Tumanski R-31 was developed and in the USA the Pratt & Whitney J-58, which was operated additionally with a fuel particularly high-energy.

With the end of the race around ever higher speeds and flight altitudes changed alsothe requirements of the engines. Were demanded now high power density with small consumption, good acceleration ability and supersonic ability. This led to the introduction of turbofans also within the military range, for instance the Pratt & Whitney F100 or the Tumanski R-33. In order to be able to cover the broad speed range,partly very complex air intakes came also with simple machines to application. Altogether the engines became ever more efficiently, in order to give to the combat pilots a good chance with aerial engagement without application type of the rocket weaponry.

civilian advancement

the first civilian airplane with jet propulsion, a Vickers Viking, which with two Rolls-Royces Nene - engines reequipped by propeller on jet propulsion was, completed to 6. April 1948 its first flight and proved the usefulness in principle of this drive form also in civilian aviation.

First militarily used types were adapted and used in civilian aviation.Thus the engines of the first jet-powered airliner, De Havilland Ghost found, likewise in the fighter De Havilland DH.112 Venom use. The Comet met with very good approval with the passengers due to the vibration-free flight. By the technical problems of the Comet, the however nothing with thatnew engines to do had, came it in the middle of the 1950er to a stagnation in the development of civilian jet engines. One preferred turbo-prop. machines, and so this engine type in its development advanced well. It was likewise nearly perfectly problem-free. Engines of this development phase, for instance Rolls-Royces the Dart, were derived still as far as possible from the turbojet engines of the first generation.

The Soviet Union worked on both engine types parallel. The highest performance turbo-prop, which develops Kuznetsov NK-12, actually for Tupolev Tu-95, was used shortly thereafter also into civilian Tupolev Tu-114 andit proved that the capacity ranges of turbojet and turbo-props did not lie far apart, with advantages in the speed with the turbojet and advantages with consumption with the turbo-prop.

The Mikulin AM-3 of the 1955 presented Tupolev Tu-104 was likewise a derivative from a military engine like the Pratt &Whitney JT3, which is actually a military Pratt & Whitney J57. 1954 were introduced the first turbofan, the Rolls-Royce Conway, which was just like the Pratt & Whitney JT3D a derivative of a turbojet engine with a relatively small Nebenstrom. First particularly for thatcivilian market developed jet engine was that 1960 presented Soviet Solowjew D-20, which opened also the short distance at the same time for this drive system, since it exhibited an acceptable consumption compared with the turbojets also at low speeds.

The turbofan became generally accepted fast. Center of the 1960er yearspractically no civilian used turbojets were more sold. Smaller jet engines like the General Electric CJ-610 for business aircraft, for instance the Learjet, were likewise demanded at the beginning of the 1960er and brought on the market like the new turbofans with high bypass ratio for the Wide Body machines, about those McDonnell Douglas DC-10 or Boeing 747. Typical representatives of this time were roll the Royce RB.211, the General Electric CF6 or the Pratt & Whitney JT9D. The Soviet Union had lost at this time the connection with the turbofans something. The further developmentseemed to show however also on the civilian market toward supersonic traffic, and so one developed in Europe Rolls-Royces the Olympus 593, a civilian variant of the military afterburner engine for the Concorde, and Soviet Kuznetsov the NK-144, which were based on military Kuznetsov NK-22,for Tupolev Tu-144.

The first oil crisis and the associated explosive cost increase during the energy use forced to a reorientation. For this time the engine efficiency was the center of attention with new developments. The CFM 56 is a representative of this time. With this engine became reequipping programs forturbojet-driven airplanes like the Douglas DC-8 or Boeing 707 offered and permitted so a further use this partial quite young machines. Aircraft noise became simultaneous the central topic. However the modern engine developments helped also here.

current one civilian development

engine of the newest generation:General Electric GE90.

The development tendency continues to point to the more economical, more efficient and more pollution free engine. In principle the development aims with civilian jet drives at a higher compression, a higher combustion chamber temperature, a higher bypass relationship, a higher reliability and longer life span of the engines.

Current engine types, so the General Electric GE90, the Pratt & Whitney PW4000 or Rolls-Royces the Trent 800 need thereby per kp/h thrust 45% less fuel than turbojets of the first generation. The engine diameter of these aggregates reaches up to 3,5 m with a thrust of approximately 55 tons (GE90-115B). One is simultaneouswith the engine diameter with a critical size arrived, since the ends of the turbine sheets of the fan reach nearly supersonic speed.

This means that the next generation of the jet engines for the fan could receive a reduction gear. Beyond that the possibility exists of adjusting the fan shovels reading and speed-sensing. Altogetherthe fan approaches so a totally enclosed propeller (English:Ducted fan). Still another step the CRISP (English continues to go: counter rotating integrated shrouded propfan) - technology, with which two adjustable, propellers moving in opposite directions sit in a fan housing. These engines, for instance SAM era the NK93, reach with acceptable outsideDimensions already a bypass ratio of 16,6.

Multi-level combustion chambers show a more favorable behavior with NOx (up to 40% of fewer nitrogen oxides), are at the CO values however because of the upper border and particularly show in the no-load operation a increased consumption.

A further possibility of improving the efficiency is the use of a waste-gas heat exchanger with an intermediate cooler. The exhaust gas temperature (z becomes. B. by a Lanzettenkühler in the exhaust gas jet) and the temperature of air before the high pressure compressor (by the intermediate cooler) lowered and air before the combustion chamber warms up. Engines with this technology become also rekuperative engines called.

The moreover Blisk become increasing with the compressor - components processes, with which compressor or turbine blades and turbine disk from a piece are manufactured or after the individual manufacture by a friction welding method are joined. This results in likewise advantages in the efficiency, there the components to be more highly loaded can anda smaller rotary mass exhibit.

New technological beginnings partially doubts of the operators, thus the airlines, face: These want technologies and engines with z, only fully developed. B. small partial's number use.

Constant conflicting aims draw off between:

• Number of parts in oneEngine,
• efficiency,
• fuel consumption,
• waste gas emissions,
• noise emissions,
• weight and
• maintenance.

For the moment fuel costs are again more highly evaluated somewhat. At one development duration of five to eight years it is however difficult to forecast the market requirements. Altogether the market of the offerers settles itself; it comes to global alliances at the engine market.

Also for the use of regenerativ energies engines with hydrogen are held ready as fuel. This fuel is perfectly problem-free for gas turbines. Since hydrogen has however with standard temperature a steam pressure of over 200 bar, a storage is possible only in solid tanks (receivers). This stands in the contradictionto the lightweight construction, which prevails in the aircraft construction. A further problem is that hydrogen diffuses strongly, thus the wall of a tank penetrates. Besides hydrogen has a clearly smaller power density than e.g. Kerosene.

Within the short-distance range slower and gasoline saving airplanes with propeller type turbines however still findtheir operational area, since they are more favorable under these operating conditions. The problem of the high noise CIM eating ions is substantially reduced thereby increasingly by employment by propfan engines.

literature

• The jet engine. Rolls-Royce, Derby 1969, 1971, 1973, 1986. ISBN 0-902121-04-9 (very well illustrated)
• Hans Rick: Gas turbine aero engines.Springer,Berlin 1993.ISBN 3-540555-86-2
• Klaus Hünecke: Aero engines. Their technology and function. Motorbuchverl., Stuttgart 1978. ISBN 3879434077
• Willy J.G. Bräunling: Airplane engines. Springer, Berlin 2004. ISBN 3-540-40589-5
• pure hard Mueller: Jet engines. Bases, characteristics, work behavior. Publishing house Vieweg, Braunschweig 1997. ISBN 3-528-06648-2

Web on the left of

• detailed description
• General Electric
• Roll Royce
• Pratt&Whitney
• MTU
• CFM
• JSC MOTOROSTROITEL (SAM era)
• Permian of engine Group
• Aerotech Peissenberg
• world of the miracles: Which turbine maintenance makes [work on

so

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