AMP - Aviation Maintenance Technician Powerplant Practice Exam

On which thermodynamic cycle does a turbojet engine operate?

1. Otto cycle

2. Rankine cycle

3. Brayton cycle

4. Stirling cycle

The correct answer is: Brayton cycle

Turbojet engines operate on the Brayton cycle, which is characterized by a continuous flow of air through the engine. In this cycle, air is compressed by a compressor, then heated by fuel combustion in the combustion chamber, and finally expanded through a turbine to produce thrust. The key processes involved in the Brayton cycle include isentropic compression, constant pressure heat addition, isentropic expansion, and constant pressure heat rejection. This allows the turbojet engine to efficiently convert energy from fuel into mechanical energy, resulting in thrust. The continuous nature of the cycle and the rapid expansion and moving parts are essential for the performance of turbojet engines, making the Brayton cycle fundamental to their operation. In contrast, the Otto cycle relies on a spark ignition process for gasoline engines, while the Rankine cycle is primarily associated with steam engines that operate using water and a heat exchange process. The Stirling cycle operates on a closed system and typically involves external heating, making it less suitable for turbojet applications.