Jet Engines and how they work

The majority of jet passenger planes have their engines slung under the wings.

The main reason for this is easy accessibility when the aircraft is on the ground.


Jet engines are mainly axial flow engines, that is air is taken in the front. The air is then compressed (by the compressor blades), the air enters the combustion chamber where fuel is added and then ignited, the air is then forced out the back of the engine turning the turbine blades as the air exits the engine.

It is important to realise that the turbine blades are directly connected to the compressor blades. The turbine blades actually turn the compressor blades, so a jet engine for a given thrust setting is in a balanced situation where the fuel being used is sufficient to create enough hot gasses to turn the turbine blades. Which then is just sufficient to turn the compressor blades to provide enough compressed air to burn. A very simple and clever bit of engineering.


This is a cutaway view showing the internal workings. There are systems such as: hydraulics and electrics which have motors driven from the jet engine.

A turboprop aircraft would have a propeller attached to the nose of the engine through a reduction gearing mechanism because the speed of the engine would be too much for the propeller.

Note how the compressor blades are directly connected to the turbine blades. On some engines you might find up to 10 turbine blades connected to just one compressor blade, others might have six turbine blades connected to three compressor blades. Most very large jet engines have at least two spools.

A spool is a shaft with multiple turbine blades and one or more compressor blades attached to the same shaft.
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