The brayton cycle:
The working cycle of the gas turbine engine is similar to that of the four-stroke piston engine. There is induction, compression, ignition and exhaust in both cases, although the process is continuous in a gas turbine. Also, the combustion in a piston engine occurs at a constant volume, whilst in a gas turbine engine it occurs at a constant pressure.
The cycle, upon which the gas turbine engine functions, in its simplest form, is the Brayton cycle, which is represented by the pressure/volume diagram, shown in figure.
The air entering the engine is compressed.
There are three main stages in the engine working cycle during which the changes discussed occur: