Aviation turbine engine stages are 1) air intake, 2) airflow pressure, which is done mechanically by the compressor, 3) fuel/air combustion, and 4) hot gas expansion, which is the conversion of hot gas into rotatory mechanical work, this being done by the turbine. This rotatory mechanical work is well harnessed at an AC power plant to drive a generator.
The reason why a jet engine is often referred to as a hot engine is because it uses hot gas to produce mechanical shaft power and thrust. Therefore, it transforms the chemical energy of the fuel combustion and the pressurized hot gas into rotatory mechanical power.
Generating thrust is possible only if the exhaust velocity of the gas is higher than the velocity at which air enters the engine through the intake. To accelerate the gas, energy must be added to the airflow within the engine, converting it into kinetic energy.
In a gas turbine engine, the increase of energy can be achieved in two consecutive steps and by two different adjacent engine components. First, pressure of the airflow is raised by the action of mechanical shaft power. This is done in the compressor portion. After it has been discharged from the high-pressure compressor, the pressurized air is heated in the combustion chamber, where gas temperature is steeply raised. The gas now is enough processed to provide mechanical work.
The first stage in the engine where hot gas in converted into mechanical power is the high-pressure turbine. As the hot gas expands and accelerates, it rotates the turbine with great force. After being discharged from the turbine, the gas is accelerated even further in the exhaust nozzle, where all remaining usable heat energy is converted into kinetic energy. The gas is ejected from the nozzle into the atmosphere where it will gradually dissipate to the conditions of the surrounding atmosphere.
Below, schematic drawing of an aviation turbine engine stages.
