What is the Difference Between Turbojet and Turbofan?

The main difference between turbojet and turbofan engines lies in their design and construction. Both are gas turbine engines, but they have distinct features that make them suitable for different purposes and aircraft types:

1. Fan: Turbofan engines have a large fan at the front of the engine, which takes in some air from outside the engine. This air is then compressed and mixed with fuel, before being sent back out to create forward thrust. Turbojet engines, on the other hand, do not have a fan and rely solely on the exhaust to create thrust.
2. Bypass Ratio: Turbofan engines have a bypass ratio, meaning that a portion of the air taken in by the fan is not used for combustion but is instead redirected around the engine core. This bypass air can create additional thrust, making the engine more efficient. Turbojet engines have no bypass ratio, as all the air taken in is used for combustion.
3. Nacelle: In a turbofan engine, the first stage of fan blades is enveloped by a nacelle, which forms a case around the jet engine. This adds mechanical complexity to the engine but also helps improve its efficiency. Turbojet engines do not have a nacelle.
4. Noise: Turbofan engines produce less noise than turbojet engines due to the lower velocity of the bypass air. This makes turbofan engines more suitable for commercial aircraft, as they are quieter and more fuel-efficient.
5. Application: Turbojet engines are primarily used in military fighter jets, which require high speeds and short ranges. Turbofan engines are used in civilian commercial airline aircraft, as they provide better performance at lower airspeeds and fly farther than military jet aircraft.

In summary, turbofan engines are more advanced and efficient than turbojet engines, making them suitable for commercial aircraft, while turbojet engines are more suitable for military fighter jets.

Comparative Table: Turbojet vs Turbofan

The main difference between turbojet and turbofan engines lies in their construction and design, specifically in the way they generate thrust. Here is a comparison table highlighting the key differences between the two:

In summary, turbojet engines rely solely on the core (compressor, combustion chamber, and turbine) for thrust generation, while turbofan engines use a combination of the core and a fan to generate thrust. Turbofans are more efficient, especially at lower speeds, and are quieter than turbojets.