Turbofan engine. Diagram of a type of aircraft jet engine known as a turbofan engine. The bottom half of the main diagram has the external casing partly removed to show the engine. The top half shows how the engine works. Most of the thrust is provided by air accelerated by the large fan (blue, centre left) that is powered by the jet engine behind it. Air enters this engine from left, passes through two compressors (orange and red), and enters the combustion chamber (yellow). Fuel is added and the mixture is ignited. The hot exhaust gases provide some thrust, but mostly drive the turbines (centre right) that power the compressors and the fan. This engine is used in large passenger aircraft.