Gas Turbine Engines – Jet Engines

Gas turbine engines are engine types that operate on the Brayton cycle, turning mechanical energy into heat energy that is used by combustion in today’s air vehicles (war and passenger planes, helicopters). The suction and compression of the air and the burning of this air by the fuel are the machines that complete the cycle by converting the energy of the air at the very high pressure and temperature to the mechanical power through the turbines.


In general the engine consists of 5 sections:

Air Inlet
Combustion Chamber
Turbine (Turbine)
Nozzle Stage (Nozzle)

The Brayton cycle appeared to be used in a two-stroke kerosene burning piston engine when the American engineer George Brayton patented it in 1872. The three components of the gas turbine consist of a gas compressor, a combustion chamber and an expansion turbine, respectively. The air is taken in, the compressor enters and is pressurized. Compressed air is burned with fuel and the burned air provides mechanical energy to the turbine stages.


Gas turbine motors with essentially the same principles (suction, compression, combustion, exhaust) are selected according to the type of aircraft to be used, the requirements (more load or speed).The Parts That Make Up Jet EngineAir Inlet (Air Inlet): The section where the air enters the motor. It has different geometries according to the speed of the plane (supersonic / subsonic).Compressor: A system that compresses air and raises its temperature and pressure and sends it to the combustion chamber.Compustion Chamber: A system that directs heat and pressurized high compressed air to turbines by burning in a 40: 1 air fuel mixture ratio (modern by-pass engines).Turbine (Turbine): Reduces the speed of air, raises the pressure to the exhaust pipe, and high-pressure air creates high propulsive power.Nozzle (Exhaust): There are fixed and moving types. It is a system that enables air to be arranged and directed according to the aircraft type.

There are basically four types of gas turbine engines. These:

  • Turbojet
  • Turbofan (By-Pass)
  • Turboprop
  • Turbo Shaft

For example, turbojet engines are used in warplanes with full speed and maneuvering requirements, and fuel consumption is not of great importance in these engines. However, turbofan engines are preferred when speed and low fuel consumption are required in passenger aircraft.

The acceleration of the air passing through the turbojets (a) is higher than the by-pass turbofan engines, while in turbofan engines the mass of the air taken into the engine is more than the turbojet engine. Depending on the two variables in the equation, the motors generate thrust force.


Turboprop engines are a system in which the generated energy is generated by rotating a separate turbine and transmitting the power from this turbine to the propeller via a shaft. In other words, it is the type of engine that turns the propeller shaft with the power it obtains from a turbojet engine running behind the propeller. High efficiency at low speeds. A small amount of thrust can be obtained while the remaining energy is discharged from the exhaust. For this reason, it is used in transport aircraft.


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