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Gas turbine engine. A photo. Structure. Characteristics.
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Gas turbine engine. A photo. Structure. Characteristics.

Gas turbine engine. A photo. Structure. Characteristics.

 

Aircraft gas turbine engines.

 

To date, the aircraft almost 100% consists of machines that use a turbine type of power plant. In other words - gas turbine engines. However, despite the increasing popularity of air travel now, few people know how to work the buzzing and whistling container that hangs under the wing of a airliner.

Gas turbine engine. A photo. Structure. Characteristics.

 

Principle of operation gas turbine engine.

 

The gas turbine engine, like the piston engine on any car, refers to internal combustion engines. They both convert the chemical energy of the fuel into heat, by burning, and then - into a useful, mechanical one. However, how this happens is somewhat different. In both engines, 4 is the main process - it's: fence, compression, expansion, exhaust. Those. In any case, the engine first enters the air (from the atmosphere) and fuel (from the tanks), then the air is compressed and injected into the fuel, after which the mixture ignites, because of what significantly expands, and eventually thrown into the atmosphere. Of all these activities, only energy expands energy, all the others are necessary to ensure this action.

And now what's the difference. In gas turbine engines, all these processes occur constantly and simultaneously, but in different parts of the engine, and in the piston engine - in one place, but at different points in time and in turn. In addition, the more air is compressed, the more energy can be obtained from combustion, and to date the compression ratio of gas turbine engines has already reached 35-40: 1, i.e. In the process of passing through the engine, air decreases in volume, and accordingly increases its pressure in 35-40 times. For comparison, in reciprocating engines this figure does not exceed 8-9: 1, in the most modern and perfect samples. Accordingly, having equal weight and dimensions, the gas turbine engine is much more powerful, and its efficiency is higher. This is the reason for such a wide use of gas turbine engines in aviation today.

Gas turbine engine. A photo. Structure. Characteristics.

 

And now more about the design. Four of the above processes occur in the engine, which is depicted in a simplified scheme under the numbers:

  • Air intake - 1 (air intake)
  • Compression - 2 (compressor)
  • mixing and ignition - 3 (combustion chamber)
  • exhaust - 5 (exhaust nozzle)
  • The Curious Case section under the number 4 called a turbine. This is an integral part of any gas turbine engine, its purpose - to provide energy from the gases that come out after the combustion chamber at great speed, and it is located on the same shaft with the compressor (2), which leads to action.

 

Thus a vicious cycle. Air enters the engine, compressed, mixed with fuel, ignited, is directed to a turbine blade, which is removed before the gases 80% power for rotating the compressor, all that remains and causes the resulting engine power which can be used in different ways.

Gas turbine engine. A photo. Structure. Characteristics.

Depending on the method of further use of this energy turbine engines are divided into:

  • turbojet
  • turboprops
  • turbofan
  • turboshaft

 

The engine shown in the diagram above is turbojet. We can say "clean" gas turbine, because the gas after passing through the turbine, which rotates the compressor exit the engine through the exhaust nozzle at great speed, and thus pushing the plane forward. Such engines are now used mainly in high-speed combat aircraft.

turboprop The engines differ from the turbojets in that they have an additional turbine section, also called a low pressure turbine, consisting of one or more rows of blades that take the remaining energy from the turbine of the compressor from the gases and thus rotate an air screw that can be either in front or Behind the engine. After the second section of the turbine, the exhaust gases actually leave virtually by gravity, having practically no energy, so simply exhaust pipes are used for their withdrawal. Such engines are used on low-speed, low-altitude aircraft.

Gas turbine engine. A photo. Structure. Characteristics.

turbofan Engines have a similar scheme with turboprops, only the second section of the turbine takes not all the energy from the exhaust gases, so these engines also have an exhaust nozzle. But the main difference is that the low-pressure turbine drives a fan that is closed in a casing. Because such an engine is also called a two-circuit engine, because the air passes through the internal circuit (the motor itself) and the external one, which is necessary only for the direction of the air jet, which pushes the engine forward. Therefore, they have a rather "plump" form. These engines are used on most modern airliners, because they are the most economical at speeds approaching the speed of sound and effective for flights at altitudes above 7000-8000 and up to 12000-13000m.

turboshaft engines are almost identical in structure to turboprop, except that the shaft which is connected to the low-pressure turbine, out from the engine and can actuate absolutely anything. Such engines are used in helicopters, where two or three of the engine is actuated and the rotor only compensates the tail propeller. These power plants are now even have tanks - T-80 and American "Abrams".

 

Gas turbine engines are also other classification atOffice:

  • on the input device type (regulated, unregulated)
  • by compressor type (axial, centrifugal, osetsentrobezhny)
  • the type of the air-gas path (straight-through, loop)
  • Turbine according to type (a number of stages, number of rotors, etc.).
  • on the nozzle type (regulated, unregulated), and others.

 

turbojet an axial compressor Has been widely used. With the engine running, there is a continuous process. Air passes through the diffuser, slows down and enters the compressor. Then it enters the combustion chamber. Fuel is also fed into the chamber through the nozzles, the mixture is burnt, the combustion products are moved through the turbine. The combustion products in the turbine blades expand and cause it to rotate. Further, the gases from the turbine with reduced pressure enter the jet nozzle and burst outward at a tremendous speed, creating traction. The maximum temperature is also present on the water of the combustion chamber.

The compressor and turbine are arranged on the same shaft. For cooling of the combustion products is served cold air. Modern jet engines operating temperature may exceed the melting temperature of the alloy rotor blades of about 1000 ° C. The cooling system of the turbine parts and the selection of heat-resistant and heat-resistant engine components - one of the main problems in the design of jet engines of all types, including turbojet.

A feature of turbojet engines with a centrifugal compressor is a compressor design. The principle of operation of such engines with similar axial compressor motors.

 

 

Gas turbine engine. Video.

 

Useful articles.

 

More components and assemblies

 

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