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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.

 

A gas turbine engine as the piston engine on any car, relates to internal combustion engines. They both convert the chemical energy of fuel into heat by the combustion, and after - into useful, mechanical. However, as it is somewhat different. In both engines going 4 main processes - is: a fence, compression, expansion, exhaust. Those. in any case, air first enters the engine (from the atmosphere) and fuel (from the tanks), then the air is compressed and fuel is injected into it, after which the mixture is ignited, because of which greatly expands and eventually released into the atmosphere. Of all of these actions produces energy only extension, all other necessary steps to ensure this.

And now what is the difference. In gas turbine engines, all these processes occur simultaneously and continuously, but in different parts of the engine, and the piston - in one place, but in a different time and in succession. Besides, the more the air is compressed, the more energy available at combustion, and to date, the compression ratio gas turbine engine has reached 35-40: 1, i.e. during the passage of air through the engine is reduced in volume, and therefore increases its pressure in 35-40 times. For comparison, in piston engines, this figure does not exceed 8-9: 1, in the most modern and perfect samples. Accordingly, having equal weight and size of the gas turbine engine is much more powerful, and the efficiency of his above. This is what caused such a broad application of gas turbine engines in aircraft 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 engines differ from turbojet that have an additional turbine section, which is also called low-pressure turbine, consisting of one or more rows of blades, which select the remainder of the compressor turbine energy from the gas and thus rotates the propeller, which can be located both in the front and rear engine. After the second section of the turbine, the exhaust gases out actually has gravity, with virtually no energy, so just exhaust pipes are used for their withdrawal. These engines are used in low-speed, low-altitude aircraft.

Gas turbine engine. A photo. Structure. Characteristics.

turbofan engines have a similar scheme with a turboprop, only selects the second section of the turbine are not all the energy from the exhaust gases, so these engines also have the exhaust nozzle. However, the main difference is that the low pressure turbine drives the fan, which is closed in a casing. Because this engine is called dvukonturnym, as the air passes through the inner loop (the engine itself) and external, which is necessary only for the direction of air flow that pushes the engine forward. Because they are rather "plump" form. Such engines are used in most modern aircraft, as they are the most efficient at speeds approaching the speed of sound and efficient when flying at altitudes above 7000-8000m 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 It has been widely used. When the engine is running there is a continuous process. Air passes through the diffuser, is braked and falls into the compressor. It then enters the combustion chamber. The camera is supplied through the injector as the fuel mixture is combusted, the combustion products move through the turbine. The products of combustion in turbine blades expand and bring it into rotation. Further, the turbine gases reduced pressure enters the jet nozzle, and with great speed digging out, creating thrust. The maximum temperature occurs at the combustion chamber water.

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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