Turbofan Engine PDF

The Turbofan is a type of ducted jet engine that is very usually used for aircraft propulsion, that is based around a gas turbine engine which achieves mechanical energy from a combination of a ducted fan and a jet exhaust nozzle. Part of the airs from the ducted fan passes through the core, providing oxygen to burn fuel to create power. However, the rest of the air flow bypasses the engine core and mixes with the faster stream from the core, significantly reducing exhaust noise. The substantially slower bypass airflow produces thrust more efficiently than the high-speed air from the core, and this reduces the specific fuel consumption.
A few designs work slightly differently, having the fan blades as a radial extension of an aft-mounted low-pressure turbine unit. Turbofans have a net exhaust speed that is much lower than a turbojet. This makes them much more efficient at subsonic speeds than turbojets, and somewhat more efficient at supersonic speeds up to roughly Mach 1.6, but have also been found to be efficient when used with continuous afterburner at Mach 3 and above. However, the lower exhaust speed also reduces thrust at high vehicle speeds.
All of the jet engines used in currently manufactured commercial jet aircraft are turbofans. They are used commercially mainly because they are more efficient and quieter in operation than turbojets. Turbofans are also used in many military jet aircraft, such as the F-15 Eagle and in unmanned aerial vehicles such as the RQ-4 Global Hawk.
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