Airbreathing jet engine

An airbreathing jet engine (or ducted jet engine) is a jet engine propelled by a jet of hot exhaust gases formed from heated and expanded air that is drawn into the engine via a compressor, typically a centrifugal or axial type. They are typically gas turbine engines. The opposite of airbreathing jet engines are non-airbreathing jet engines, such as rocket engines, for example, which are propelled by a jet of hot gases created by the chemical reaction of two or more compounds internally. While the majority of the mass flow of an airbreathing jet engine is provided by air taken from outside of the engine and heated internally, using energy stored in the form of fuel, a rocket engine's fuel provides both the energy and the mass flow to create thrust.

All practical airbreathing jet engines are internal combustion engines that directly heat the air by burning fuel, with the resultant hot gases used for propulsion via a propulsive nozzle, although other techniques for heating the air have been experimented with (such as nuclear jet engines). Most modern jet engine designs are turbofans, which have largely replaced turbojets. These modern engines use a gas turbine engine core with high overall pressure ratio (about 40:1 in 1995) and high turbine entry temperature (about 1800 K in 1995), and provide a great deal of their thrust with a turbine-power fan stage, rather than with pure exhaust thrust as in a turbojet. These features combine to give a high efficiency, relative to a turbojet. A few jet engines use simple ram effect (ramjet) or pulse combustion (pulsejet) to give compression.

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