What is the main difference between a turbojet and a turbofan engine?

The main difference between a turbojet and a turbofan engine lies in the design and functionality of the engine components. A turbofan engine incorporates a large fan at the front of the engine, which is responsible for generating additional thrust by accelerating a larger volume of air than the core engine alone. This fan produces significant thrust, especially at lower speeds, which improves overall efficiency, fuel consumption, and noise reduction compared to a turbojet engine.

Turbojet engines, in contrast, rely solely on the high-speed exhaust from combustion to produce thrust, lacking a fan. This design makes turbojets more suitable for high-speed flight, but they are less efficient at lower speeds compared to turbofans.

Understanding the role of the fan in a turbofan engine is crucial as it not only enhances thrust production but also allows for better performance characteristics, particularly in commercial aviation where noise and fuel economy are critical considerations.