Final answer:
The APU air inlet plenum functions to control airflow into the Auxiliary Power Unit, reducing turbulence and evenly distributing air. It also protects the APU from foreign objects and aids in noise attenuation, ensuring reliable and safe auxiliary power for aircraft.
Step-by-step explanation:
The function of an APU air inlet plenum is to ensure a smooth and controlled flow of air into the Auxiliary Power Unit (APU) of an aircraft. The plenum acts as a buffer and a conduit, which helps to reduce turbulence and provides an even distribution of air. This is important for the optimal operation of the APU, which is used to generate power for various systems on the aircraft when the main engines are not running, such as during ground operations or in case of in-flight emergencies.
The APU air inlet plenum also serves to protect the APU from foreign object damage by incorporating filtering systems, and sometimes it's designed to provide noise attenuation. Altogether, this component is crucial for the reliability and safety of the APU system, ensuring that the necessary auxiliary power is available whenever needed.