Heat engines are divided to two types :

A-External combustion engines:

In this type combustion takes place outside the engine same as steam turbines which use steam to run , Steam is produced by a boiler.

Steam turbine:

B- burning engines:

The internal combustion engine is an engine during which the combustion of fuel occurs in a very combustion chamber. the expansion of the extreme temperature and Pressure gases, directly applies force to a movable component of the engine, like the pistons in diesel engines or turbine blades in turbine and by moving it over a distance, generate useful energy.

Diesel engines:

Gas turbine:

1- air compressor :

suck air from atmosphere and compress it to the combustion chamber.

2- combustion chamber :

the combustion is happening due to the injection of fuel and compressed air and will produce gases with high pressure and temperature apply force to turbine blades which will rotate in
high speed.

3- turbine :

consists of a wheels with blades fixed on a shaft , when the gases apply force to the blades they rotate the wheels with the shaft and run with high speed. The rotation of the shaft is the useful mechanical output.