Jet engines (including jet engines and jet turbines) is a gas turbine, which is used primarily as a machine and it works on the principle of the style of Jet. Sucking air and encourage the production of combustion air, and partly as a drive generated by a fear of shear force. Because unlike a rocket engine oxygen needed for combustion from inside the engine air intake Rolls-Royce RB211, a turbofan engine in the 1970s, used for example in the Lockheed L-1011.
Jet engines are extremely important to commercial aviation. By far the largest part of the transportation services provided to aircraft jet engines ..
Effect principle Stocks surge as well as speed, temperature and pressure gradients in the jet engine.
A jet engine is in its current form is almost always a turbine jet engine. It sucks in air compress Detention in itself) in a compressor (booster. In the subsequent burning of the fuel (kerosene is usually injected) and the mixture is then burned. Combustion increases the temperature and flow velocity, static pressure of gas drops a little. Gas is supplied to the flow energy is then converted into the rotation behind next turbine, where some of the gas expanded further. turbine compressor is used as a motor, such as generators and hydraulic pumps. Depending on the design of the machine, for example, when a turboshaft engine, the gas energy is almost completely removed and carried out by the turbine. Gas expands in the turbine nozzle is positioned at the back almost to withstand the pressure, where flow velocity is further increased. In the nozzle, the actual power (thrust) by gas menhilang. For many people in the military and supersonic jet aircraft operating area that is in back to improve the performance of turbines have not installed the afterburner.
This process can easily be compared to piston engines, which is held every four cycles - intake, compression, combustion and pengeluaraan - simultaneously and continuously. The reaction produced in accordance with the principles of Newton's style is the impetus generated. The advantage of the jet engine to drive piston is efficiency at high speeds (especially at supersonic speeds) and high altitude in the high power density.
Simple jet engine accelerates a relatively small mass of air is very strong, while the propeller accelerates a large mass of air is much weaker.
Disadvantages are the high precision manufacturing costs and higher costs related to procurement. This includes the drive is almost entirely from the market of sports and the plane trip. Exceptions to the engine and the Cougar Microturbo Microturbo TRS-18 used by Bede BD-5 Amateurbauflugzeug MicroJet. Turbine jet engine compared to the piston engine / propeller combination is sensitive to foreign substances. Even the increased levels of dust can drastically reduce maintenance intervals. Absorption of water droplets, however, is problematic even in heavy rain.
Beginning of the machine carried by the compressor was brought to minimum speed.This can be by injection of air, electricity, carried by a separate turbine with reduction gear (air starter / starter cartridge) or with a small internal combustion engine. It is commonly used today, an electric starter for small engines, all engines from Airbus or Boeing commercial aircraft have a starter. Boeing, however, was the Boeing 787 on the road, even with large engines (GE Nx use) an electric starter. This is another step towards a new concept of "Electric Engine".
After reaching a minimum speed of the fuel is injected into the combustion chamber and ignited by one or more spark plugs. After the ignition of fuel and other speed increases, the engine is turned off, the burning of continuous decline. Control the speed range between idle and full load and up to 95%, but usually only about 40%.The power curve is as for all turbomachinery in approximately logarithmic, in about 90% speed will be about 50% of the power available at 100% then 100% will be allocated power.
kebocooran air compressor will be removed from the so-called, is equipped with a pressurized cabin. The principles of physics Free Joule loss process. Driving efficiency as a function of speed.
For the calculation of the efficiency of a jet engine is the best Joule cycle. Critical process parameters are pressure and temperature differences. Ideally, therefore, very dense, we choose the highest possible turbine inlet temperature T3 and the working gas is then expanded through a nozzle as large as possible to minimize the temperature.
Shear formula and the efficiency of propulsion
Electricity generated by the engine thrust is equivalent to being in the case of constant velocity and constant altitude, aircraft drag, thrust must be greater than the resistance when the plane is intended to accelerate.
This can be further simplified formula under negligible shear quantity of fuel and the assumption that the outlet pressure in accordance with the combustion gases with ambient pressure:
S = \ dot m_l (C_5 - c_0).
S Thrust in N \ Dot m_l air mass flow in kg / s
c5 gas exit velocity in m / s
c0 the speed in m / s
To boost efficiency, however, applies
\ Eta_v = \ frac (2) (c_0) + c_0 C_5.
So currently used in civil aviation with a high pass ratio engines, where large air mass flow is relatively slow to leave the machine, which is more efficient, not to mention the noise reduction effect. This type of jet engine Gas turbines The basic structure of an aircraft gas turbine
Aircraft gas turbine consisting of inlet, compressor, combustor, turbine and exhaust nozzle. Compressor and turbine are usually one or more mechanical wave is connected. With freewheeling turbines that are part of the turboprop aircraft used, the turbine, which drives the propeller mechanically separated from other components. Inlet air
Opening the air inlet is located in the direction of forward flight. Part of air inlet vanes increases from front to back. The mass of the incoming air is slowed down by it, and increase the pressure and density there. For engines designed for supersonic flight, the air flow in the intake slowed by a series of oblique compression shocks in subsonic, supersonic flow in because the compressor will not work. Should a machine can be used in a variety of supersonic speeds, the inlet cross-section will generally be adjusted by adjustable diffusers (variable intake cones or ramps) for speed. Fan
In most modern commercial jet engines used prior to the first compressor is a Fanstufe. This is often referred to as the first compressor stage. In Nebenstromtriebwerken ensure the air that passes through a bypass between the outer casing and the turbine engine cowling round. The fan is now on the same shaft with a low pressure. But there are also developments for decades to improve the efficiency of the fan (wind). The latest development is a reduction gearbox between the fan and low pressure. This leads to an increase in the efficiency of the whole machine, because the propeller is running in an optimal speed range. So Nebenluftstrom slowed so as to minimize kelebihaan at the end of the engine fuel consumption and noise emissions. In addition, the centrifugal forces acting on the propeller fan, illustrated by a lower rotational speed decreases. Thus, disks and blades can be dimensioned less. Hause blocks coated with Kevlar to prevent the event kessalahaan of the rotor of a pass-through of the machine body. Compressor
compressor stage of the General Electric J79. Without stator
At the air inlet is the compressor. At the beginning of the machine (General Electric J33, Rolls-Royce Derwent) single-stage centrifugal compressor is used, which is now only used in small jet engines and turbines, wave.
Modern axial compressor has several stages, each of which may consist of several compressor impellers with a knife. The compressor has a duty to give the incoming air mass and convert the kinetic energy into pressure energy. This is done in diffusorförmigen (ie widening) of the interstices of the compressor blades. According to Bernoulli's law increases on increasing the channel cross-sectional area, static pressure, while the flow velocity decreases. Now the kinetic energy loss is compensated in a rotor. Complete compressor stage of an axial compressor rotor thus rose from a stage where both pressure and temperature and speed, and Statorstufe where the pressure rises at the expense of speed. The Rotorstufen arranged sequentially on a single drum, with modern machinery and up to three drums. Statorstufen permanently mounted on the inside of the compressor
The older design with 17 times the compression stages, only reaching 12,5:1 compression ratio (pressure at the end of the compressor: menahaan pressure), while the new developments with fewer stages to achieve a much higher density (43.9: 1 with 14 levels in the GP 7000 for the Airbus A380). This is made possible through the improvement of compressor rotor profile, the result even at supersonic speeds (peripheral speed of the propeller and wind speed) gives a very good flow properties. The pure flow velocity will not exceed the local sound speed, because otherwise it would reverse the effects of channel diffusorförmigen. Here it must be remembered that the local sound speed (due to rising temperatures in the compressor and then to 600 ° C) also increased. Combustion chamber
CAD Drawing: a combustion chamber Turbofantriebwerks.
High compression of air causes a sharp rise in temperature. So-hot air then flows into the combustion chamber, where the use of fuel. It ignited by the spark plug and the engine started. Furthermore, continuous burning occurs. Because the exothermic reaction of oxygen-hydrocarbon mixtures are updated causing a rise in temperature and gas expansion. Machine parts is strongly influenced by the temperature to 2500 K (about 2200 ° C). Without cooling can also be a high-quality ingredients (often nickel-based alloys) can not withstand this temperature, because it reduces their power as early as about 1100 ° C is very strong. Therefore, direct contact between flame and a jacket (coat) is prevented. This is done by so-called "secondary", not directly into the combustion zone, but herumgeleitet into the combustion chamber and then through the holes in the metal protrusions of scale-built room, and entered into this as an incident between the combustion gas and the wall combustion chamber sets. This event is called refrigeration.
About 70 to 80% of the total mass of air from the compressor to be used as a secondary, like the others come directly into the main combustion chamber. The average speed of axial flow engine is about 150 m / s. Since Zündgeschwindigkeit of fuel used is relatively low (around 5-10 m / s), flame stability through the recirculation flow in the primary zone will be ensured. This is usually accomplished today by twisting the primary air entering the combustion chamber. It is always hot combustion gases back into the fuel nozzle, and thus encouraged to ensure that combustion begins. Furthermore, in the immediate vicinity of the air flow rate is reduced (about 25-30 m / s) to prevent the extinction of the fire and to achieve optimal combustion.The combustion chamber is determined by the interpretation of the content of pollutants in the exhaust. Distinction is made between the combustion chamber tubes, combustion chambers and annular combustion chamber pipe ring.
Tube combustor
GE J79 firing tube.
This type of combustion chamber is suitable for engines with centrifugal compressors, such as in particular in the early development in the UK and is now used in turboprops. This is caused by different diffusers of centrifugal compressors, which had split the air flow. Each room has a primary and secondary air system. Zündstege combustion chamber is connected. In general, about eight to twelve pipes combustion chamber is arranged radially on the machine. Very small turbines, such as APU's, has only one tube combustor. The advantage of the ease of development, easy maintenance and fuel distribution facilities is good harming the development of such a high weight. Also, the flow compared with a favorable combustion chamber design.
Ring tube combustors This design combines the combustion tube and the annular combustion chamber and is suitable for very large and efficient gas turbines, because they Dapa tmengontrol themselves mechanically very stable. Significant difference to a combustion chamber is a common combustion chamber outlet. This type occurs in jet turbine engines
Annular combustors Annular combustion chamber arrangement is optimum for gas turbine jet engines dynamically They are quite easy and can be built not long, because there should be a diversion from the compressor to the turbine. The combustion chamber has a fuel injection valve, which provides fuel to the annular combustion chamber. However, maintenance is rather difficult. Development is very complex, because the gas flow must be calculated in three dimensions in space. Annular combustion chamber is now common type of air jet engines.
* CAD Drawing: turbine from Turbofantriebwerks: the high pressure turbine compressor, low pressure turbine through a coaxial wave hit the fan
Turbine
The gas that comes out backwards and then taken to the turbine. This drives the compressor through a shaft. For most single-flow engine is the largest part of the kinetic energy is used. So just so much energy to the turbine as required for the operation of the compressor. Today mostly used two-or three-stage turbine that drives the shaft through every part of a multi-stage compressor as well.
Cooled turbine blades are usually expensive (internal and / or film-cooling) and now consists of the most resistant alloy. These materials are also frozen in the desired direction, then preserved in their crystal lattice, namely the set and then allow to make the material properties along the highest burden of the optimal effective. The first phase of the high pressure turbine increased from Einkristallschaufeln. Located at the gas knife is protected with a layer of ceramic high temperature and erosion. Min due to high load at speeds of more than 10,000 /. due to mechanical or thermal damage can not be ruled out forever. Therefore, the casing of the turbine will be designed accordingly. In front of the fan blades are Kevlar mats used to prevent engine parts bearing structures are damaged or injure people. The high temperature in the turbine area to prevent the use of Kevlar. Nozzle
Turbine rear mounted a nozzle through which the gas is accelerated to high speeds and thus generate thrust, which is why so-called jet nozzle. That (at the turbine outlet pressure turbine outlet pressure gradients that exist - pressure resistance) are fully implemented at this speed. As long as the ratio of pressure turbine outlet pressure to the pressure, tahaaan less than what is called a critical value of about two, the pressure at the end of the nozzle equal to the pressure in the area. A convergent nozzle then enough. But if the pressure ratio is greater than the critical ratio, then the jet to accelerate at supersonic speeds. Convergent-divergent nozzle, the nozzle with a narrow neck, which is advantageous, because the impulse is greater and the beam appears with weak compression shock, which is significantly quieter.
Engine with afterburner nozzle causes the gas stream prior to further fuel that reduces the combustion temperature due to additional costs of gas density. Free jet exit velocity is then larger for the same nozzle pressure and thus the ratio of thrust. Engine with afterburner needs an adjustable nozzle, because the nearest nozzle diameter must be enlarged in Nachbrennerbetrieb. Parameter
A turbine jet engines have different properties. Here is a list of key technical parameters to make quick comparisons with different jet engines to be able to:
* Type of compressor (radial / axial / mixed / special) * This type of turbine (radial / axial / mixed / special) * Type of combustion chamber * Number of Fan Levels * Total Niederdruckverdichterstufen * Total Hochdruckverdichterstufen * Total Hochdruckturbinenstufen * Total Niederdruckturbinenstufen * Wave number * Air flow rate (kg / s) * Engine Length * Engine diameter * Dry * Shear * Bypass * The compression ratio compressor * Specific fuel consumption (kg / KNH)
Single stream jet engines (turbojet) Components of the first generation with a centrifugal compressor turbojet
The turbojet is the simplest form of a wave ray machine. It consists of a gas turbine in the exhaust gas is used only as a media drive. Machines usually only have a wave through the compressor and turbine connected. The total gas flow through the combustion chamber. Because of the high-speed driving out the media, it must be driven at lower speeds of vehicles (mostly aircraft), one per day standard, low efficiency and produce high noise levels. Especially under the speed of sound, specific fuel consumption is high, so this machine from economic reasons and ecology is no longer used. This machine is very compact and relatively easy maintenance. Their operating time, especially in the years after World War II until the mid-1960s, is good in both civil and military aviation, with the turbojet could last longer in military applications, and is still used today for different types of aircraft (for example : F-4 Phantom, MiG-21). Turbofan jet engines (turbo-fan, mantle flow, bypass machine) Of the turbofan engine CFM56 CFM International.
turbofan
Triebwerksart now a common form of jet engines. Almost all of today's manufactured turbine jet aircraft will be equipped with a turbo fan.
Turbofan engine is characterized here by at least two jack shafts and from the first stage of a larger compressor, driven by the turbine itself. Behind him, the air flow is divided into the airflow, which enters the real gas turbine, and the outside air flow out through turbines. Ordinary bypass ratio turbofan technical characteristics, the ratio of the amount of air flowing past the outside driven by the fan (blower), with the amount of air flowing through the gas turbine.
A turbofan offers several advantages compared to the turbojet:
* Improving the efficiency of the engine with the average speed is lower than the driving jet of air and thus fuel consumption is lower. * Reduction of noise generated by the hot, fast and very hard to Turbinengase surrounding wet with cold gas flow and the calm of the first stage.
on the present use so that the aerodynamic drag with a large diameter and thus according to the engine wide-bodied aircraft during supersonic flight is not too high, Turbofantriebwerke relatively low-pass ratio, the amount of air that is distributed in the combustion chamber, with the amount of air through the combustion chamber is (up to about 1.5) and the noise is relatively low compared Turbojettriebwerken. In the civilian sector and the transport planes have engines with a bypass ratio of about 9:1, the secondary (cold) for the primary (hot) air, is used. Turbine propeller (turboprop)
turboprop
A special case is the drive airscrew (propeller) through the turbine. This type of drive is called a turboprop. Gas turbines have been, at least two waves. The propellers are driven by a reduction gear of the drive turbine. The first turboprop aircraft already appeared in the late 1940s based on turbo-jet engines. Especially for short trips and at medium altitude is the most economical engine turboprop aircraft. Acoustic emission is dominated by the propeller and propeller blades with small Mach number is low. The sound emitted by the jet is relatively low, because the jet exhaust velocity is greatly reduced through the drive turbine. Exhaust gas flow, only contribute to the relatively small level to drive, but included in the calculation of the wave comparative performance to performance. Compared with reciprocating engines, turbines are characterized by a high power density and long service intervals. A similar turbine is also used in helicopters.
To reduce aircraft fuel consumption, the use of propeller turbines will be discussed at Flugmachzahlen higher. To limit the losses generated by the propeller of a twist to come in this case only the counter-rotating propellers are concerned, either through a planetary gear or is driven by two counter-rotating low pressure turbine. Acoustic emission propulsion is the subject of research and is critical to commercial success of the propeller will drive high Flugmachzahlen.
RAMJAET
In a ramjet engine, air is supplied to the combustion chamber is not driven by mechanically moving (eg axial or compressed) centrifugal compressor, but by utilizing a dynamic pressure. Ramjet engine is characterized by maximum simplicity, because they require almost unable to move. The main drawback is that they can not produce boost. A ramjet can operate only after it was taken to a speed that was built for sufficient back-pressure operation. In the ramjet engine can still distinguish between the ramjet or scramjet (Supersonic combustion ramjet) engine. In the past, the incoming air reserve, even after compression in the combustion chamber and supersonic speeds (supersonic combustion - Supersonic Combustion).
While the principle patented before the First World War, it took more than 30 years, until the first ramjet. During the Second World War, the development of this technology in Germany has been driven, an experimental specimen tested in a Dornier Do 217 in flight. In the 1950s, a similar experiment carried out mainly in France. The trial culminated in a car test Nord Aviation 1500 Griffon N, but in the end they failed because of non Adaptee ramjet. Ramjet engine is currently used by large and supersonic unmanned air vehicles. They compete with the rocket engine.
In a scramjet, the X drive run-43A, a technique developed by NASA's hypersonic plane. November 16, 2004 reached a missile while just under 10 seconds to ten times the speed of sound, which reached its highest ever with engine speed. Nadi or Verpuffungsstrahltriebwerk
Nadi or Verpuffungsstrahltriebwerke completed, compared to the turbojet engine is also relatively easy to use. Unlike other jet engines, combustion runs periodically. The most common machine in the front (air intake), a valve device (vibrating valves) to regulate the air, and combustion chamber behind a relaxation area where you can soothe the hot gas.
In the combustion chamber of the engine is air, is injected into the fuel. After that, the air fuel mixture ignited. There is a deflagration. Through expansion and the resulting pressure to close the valve closed, the combustion gases can escape only produces boost backwards and forwards. After a relaxing gas, not wind through the inertia of the gas flowing in the torque tube to a vacuum in the combustion chamber, where the valve is open the lid again. This allows fresh air to follow. After another injection of a mixture of fuel burned by the hot gas residue in the combustion chamber. This sequence is repeated periodically. Helmholtz resonator system provides dar. This design also gives a boost to his feet.
As for the ramjet engine and Pulsstrahltriebwerke limited spectrum of applications.The most famous representative of this engine technology during the Second World War is the Argus As 014 engines of the Fieseler Fi 103 (better known as a "weapon of retaliation V1). It also comes with a Messerschmitt Me 328b, a prototype for a fighter of the year 1943, which is used.
Currently Verpuffungsstrahltriebwerk in the air is no longer used. Disadvantages include large volumes (with up to 140 dB sound pressure), produced by the periodic termination, slide the relatively low compared to fuel consumption and outstanding heat from the engine (~ 1000 ° C). Only a smaller scale, still used on model airplanes. History Beginning
Propeller aircraft reaches a maximum speed of 700 km / h, which can be enhanced by a propeller that can be customized and different techniques to improve engine performance slightly. However, the goal is to build planes faster than 800 km / hour to fly, can not be realized without the development of new propulsion technologies. Early recognized as the best solution may be applied only when their styles Jet sufficient knowledge in the field of aerodynamics, thermodynamics and metallurgy.
The first self-developed gas turbine running Aegidius Elling of Norway was in 1903.
Victor de Karavodine then developed in 1906, the basics Verpuffungsstrahltriebwerks. Marconnet Georges struck in 1909, before this Triebwerksart as jet engines for aviation applications. Apart from all this is the first turbojet engine design that powered, in addition to missiles, aircraft.
A branch line for the production of jet engines were hybrid designs in which the compression performed by an external energy source. In such a system (Thermojet Secondo Campini), is activated by a conventional gasoline engine, mixed with fuel and then burned to produce thrust. There are three specimens of this species, and that the Coanda Henri Coanda-1910, which later developed more Campini Caproni CC.2 and Japanese Tsu-11-drive it for planes Ohka kamikaze aircraft scheduled for the end of World War II. None of the drive is successful, then finally CC.2 turns more slowly than conventional aircraft with the same engine. Development of the engine by Frank Whittle Frank Whittle
The Englishman Frank Whittle filed in early 1928 various proposals for the construction of jet engines. He thought of a propulsion system that will perform at an altitude of 35,000 m job, but could not win a couple.
The key that can be used is a gas turbine jet engines, where the energy came to leave the compressor of the turbine itself. Work on such an integrated design in Britain from 1930 Whittle filed a patent for such appropriate drive, known for his 1932 machine had a single stage turbine, driving a centrifugal compressor.
1935 Rolf Dudley Williams founded the company Power Jets Ltd.. Whittle and sat as a development chef. Whittle to build a gas turbine engine, type U, the first test run on 12 April 1937 carried out and showed good results. Coordinating Ministry of Defence (War Department), then make the money available, and began developing the type of space W.1. Gloster Aircraft Company assigned to produce a suitable aircraft. So, the first is on 15 experimental aircraft in May 1941 e 28/39. Kenneth Patchen engine development
Apart from Whittles Work From Kenneth Patchen 1935 in Germany, his work on the same machine. Ohain turned to Ernst Heinkel, who immediately recognize the benefits of the new drive concept. Ohain in collaboration with master mechanic, Max Hahn, a new department within the company Heinkel.
First drive - Heinkel HES 1 - already running 1937 Unlike Whittle Ohain initially used as a hydrogen fuel, which caused the initial success. The following designs which culminated in the Heinkel HES 3 to 550 kp (about 5.4 kN), which is built into a specially designed Heinkel 178 After impressively short development time, this prototype was flown in August 1939 as the world's first jet aircraft. As the first jet engine in the series are then produced Jumo 004 in 1942, which among other things, the Messerschmitt Me 262 twin is used. Military developments during World War II One of the first jet aircraft engines: the Junkers Jumo 004 Arado Ar 234B Blitz - One of the first bomber with jet engines.
German turbojet engines are all equipped with axial flow compressors and thereby have a diameter smaller than the centrifugal compressor England. The main line of development is the Junkers Jumo 004, which with around 4750 units in the Messerschmitt Me 262 and Arado Ar 234 is used. Then the production-ready and only produced 750 pieces of BMW 003 used in the Heinkel He 162 and Arado Ar 234
Development priorities is to increase the speed of the German lines, fuel consumption, weight and stability needs to be improved in the development process.After 1941, it is necessary to achieve the new performance brand of 800 kgf (about 7.8 kN) for. It was not immediately use gasoline, but diesel fuel, which is easier to get and have a higher boiling point. Now necessary, however, a modified combustion system.
At the end of the war, approximately 6,700 types of engines, BMW 003 and Jumo 004 were produced, which still achieve an improvement in performance, which then was about 900 kgf (kN is around 8.8). HES yang Heinkel 011 engine running when the war ended in 1300 kp (12.7 kN) and the strongest Turbojettriebwerk world. Heinkel and BMW's first turboprop engine also in development. Rolls-Royce Derwent
Based on the W.1 engine was developed in Britain, Rolls-Royce Welland, a mutation of 7:56 kN thrust. This machine was originally used in the Gloster Meteor. Further variation is uprated Rolls-Royce Derwent, also used in the Meteor. Both engines are the only one in the UK, which is used for fighter aircraft. In this concept - the centrifugal compressor, axial turbine combustion chamber and the tube - put the whole line of the British jet engine technology development in the early 1950s.
The first operational U.S. jet engines are General Electric J31, which also has a radial compressor and axial turbine and the Bell P-59 is used. A much more powerful Allison J33 was based on the de Havilland goblins. It was used in the Lockheed P-80 and came to be used in the Second World War, in fact too late.
In the Soviet Union and in Japan during World War II found no significant developments occurred in the jet engine.
Military construction Engine fighter of the 1970s, Volvo RM8B turbofans, among others, used in the Saab Viggen.
Knowledge formed the basis for further developments in the military alliance of the Warsaw Pact and NATO. The purpose of the first development is a measure of performance without the need to be changed. Which quickly led to the development Nachbrennertriebwerke, carrying a little extra weight is a significant performance improvement. However this is achieved at the expense of fuel consumption. Typical representative in the 1950's in the west, General Electric J79, in the east, which Tumanski R-11. Both engines allow progress in the speed range of up to Mach 2 Technical problems largely resolved. It was a boost to Mach 3, in the mid-1960s called for further development. In the Soviet Union was developed Tumanski R-31 and U. S. Pratt & Whitney J58, which is operated as a thermal load at those speeds with a special fuel (JP-7).
With the end of the race for higher speeds and altitudes change the requirements for the machine. Now the required high power with low consumption, excellent acceleration capability and supersonic capabilities. This led to introduction of the turbofan in the military sector, such as Pratt & Whitney F100 or Tumanski R-33. To cover a variety of speeds to be, partly air supply is very complicated even for simple machine to use. Overall, a more powerful engine to give fighter pilots a better chance in a dogfight with no possibility of using missile weapons. Civil construction
The first civil aircraft with jet engines is the Vickers Viking, which has been tentatively fitted with two Rolls-Royce Nene from propellers to jet engines. He graduated on 6 April 1948 First flight, and shows the main application of these drives in the form of civil aviation.
First used in military type have been adapted and used in civil aviation. Thus, the first series jet aircraft, is the de Havilland Comet ", a de Havilland Ghost engine fitted to the aircraft at the de Havilland DH 112" Venom found "is used. Comet was in the passenger because it is fast and vibration-free flight was initially very well received.Through a series of misfortunes mysterious comet plane (but not with the new machine to do) but the mid-1950s there is considerable skepticism by passengers and airlines from jet aircraft and to a stagnation in the development of civil jet engines.One option turbo-prop aircraft, engines and so it made good progress in development. He is also almost entirely without problems. Machine phase of this development, such as Rolls-Royce Dart, still largely derived from what has been Turbojettriebwerken first generation.
The Soviet Union working in parallel on both types of machines. Previously the most powerful turboprop, which had Kuznetsov NK-12, actually for the Tupolev Tu-95 which was developed shortly afterwards in civilian Tupolev Tu-114 proved to apply and that the service ranges from the turbo jet and turboprop aircraft are not far apart, with the advantage in speed turbojet and benefits of consumption in the turboprop.
The Mikulin AM-3 in 1955 Tupolev Tu-104 is implemented as an instance of the military machine, such as Pratt & Whitney JT3, which is actually a military Pratt & Whitney J57. 1954, which introduced the first turbofan, Rolls-Royce Conway, who, like Pratt & Whitney JT3D Turbojettriebwerks derivatives and only one showed a relatively low-pass ratio. The first specifically designed for civil jet engine market was introduced in 1960, the Soviet Soloviev D-20, the same drive that opened a short distance, like the show than turbojets at low speeds and consumption is acceptable.
The turbofan asserted itself quickly. The mid-1960s that sold almost no civilians turbojet used more. Smaller jets such as General Electric CJ-610 is for business jets, such as the Learjet, as called for in early 1960 and brought to market as new turbofans with high bypass ratio for wide-body equipment, such as McDonnell Douglas DC - 10 or Boeing 747 Vice typical This period is the Rolls-Royce RB211, General Electric CF6 or Pratt & Whitney JT9D. The Soviet Union has disappeared at this time related to the turbo fans something. Further developments, but also seems to civilian markets in the direction of supersonic transport shows, and so they developed in Europe, Rolls-Royce Olympus 593, a civilian version for Concorde and the Soviet military Nachbrennertriebwerks Kuznetsov NK-144, based on the military Kuznetsov NK-22 was based , for the Tupolev Tu-144.
The first oil crisis and rising cost of explosives related to energy are forced to rethink.Since that time, machine efficiency in new developments stand in the foreground.CFM 56 which is representative of this period. With this machine is to retrofit aircraft turbojetgetriebene such as Douglas DC-8 or Boeing 707 and offer it allows partial re-use of this machine is relatively young. At the same time the noise is a central theme.Again, however, aided the development of modern machinery. Currently the construction of civil The latest generation of engines: General Electric GE90.
The trend is still pointing to the development of more economical, efficient and environmentally friendly engines. Basically, the construction is intended for civil jet engines to a higher density, higher combustion temperatures, higher bypass ratio, greater reliability and longer engine life.
When the engine type, General Electric GE90, Pratt & Whitney PW4000 or Rolls-Royce Trent 800 consumes relatively by 45% compared with first-generation turbojet reduce specific fuel consumption. These engines achieve aggregate diameter up to 3.5 meters, with a pressure of about 500 kN (GE90-115B).
The current trend is also in the direction of the next generation of equipment for reduction of jet engine fan / blower (directed) can get. The advantage is that the low pressure turbine can be operated at higher speeds, which promises better efficiency.In addition, the possibility of the fan rotor load and engine speed must be adjusted.Overall, the approach to the fan blades as encapsulation Fan channel. Another step by CRISP (UK: an integrated counter-rotating shrouded Propfan) technology, sitting with two adjustable, counter-rotating blades like a fan. This machine, like the NK-93, achieved at an acceptable external dimension has had bypass ratio of 6.16.
Multi-stage combustion behavior favorable to NOx (up to 40% less nitrogen oxides), which with the values of CO, but the upper limit and showed an increase in consumption of useless. Through a multi-stage combustion, the maximum temperature will be reduced in the combustion chamber, which is mainly responsible for the formation of NOx is
Another way to improve efficiency, the use Abgaswärmeübertragers with intercooler.This will reduce exhaust gas temperature (eg by Lanzettenkühler in the gas stream) and the air temperature in front of the high pressure compressor (with intercooler) and heats the air before the combustion chamber.
In addition, the compressor will be more blisk component of the process in which the propeller or turbine compressor and turbine wheels made of one piece or joined with the production of each of the friction process. It also provides advantages in efficiency, because the components may be subject to higher loads and has a lower rotating mass.
Approach to new technology sometimes worries operators, so the flight on the contrary: They want to use only fully mature technology and machinery as part of a low number.
This became a constant conflict between the objectives:
* The number of parts in a machine, * Efficiency, * Fuel consumption, * Exhaust Emissions * Noise * Weight and * Ease of maintenance
In the construction period of five to eight years, it is difficult to predict market demand.
At this time, fuel costs will be assessed again somewhat higher. In looking for alternative fuels, pursued a different approach: on one Airbus A380, Qatar Airways is one of four machines for testing purposes on the operation of GTL fuel is converted Boeing was also tested in a collaboration with Virgin Atlantic on one engine of the 747-400 the use of coconut and babassu oil biofuels. Will also be investigated for the use of renewable energy as an engine with hydrogen fuel. Of turbine technology produces up easily, the weight of hydrogen at the same energy content even lower than kerosene, but it must remain refrigerated, hydrogen (-253 ° C) and requires to own low-density liquid, large volume. All these investigations are still at the stage that can not be an alternative fuel in operating regular daily operations in the years to expect.
In the short distance to services, however, are still slower and more fuel-efficient aircraft with turboprop engines you can use them, because they are better under these conditions. The higher the noise problem through the use of a propeller with more reduced significantly. Machinery market
Generally, market focus and coming provider of global alliances in the engine market.Examples are the merger between General Electric and Pratt & Whitney Engine Alliance joint venture called for the development and construction of GP7200 engines.In the field of military cooperation on the basis of multinational projects are often imposed by the interests of national work-related. For example, establishing Industria de Turbo Propulsores (Spain)), MTU Aero Engines (Germany, Rolls-Royce (UK) and Snecma moteurs (France) for the development of the A400M engine specific EPI Europrop International GmbH
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