AMP - Aviation Maintenance Technician Powerplant Practice Exam

How does a centrifugal compressor increase airflow pressure?

1. By compressing air with fixed blades

2. By throwing air outward using a rotating impeller

3. By creating a vacuum in the combustion chamber

4. By decreasing engine speed

The correct answer is: By throwing air outward using a rotating impeller

A centrifugal compressor increases airflow pressure primarily by utilizing a rotating impeller to throw air outward. As the impeller spins, it accelerates the air and directs it radially outward into a diffuser. This process converts the kinetic energy of the fast-moving air into increased pressure as it slows down in the diffuser. In contrast to fixed blades, which may not provide the dynamic pressure increase characteristic of centrifugal systems, the impeller's motion is crucial for enhancing airflow. The action of throwing air outward enables the compressor to achieve a significant rise in pressure relative to the incoming atmospheric conditions. This mechanism is fundamental in many applications, such as gas turbines and turbochargers, where efficient airflow compression is essential for performance. Other options, such as creating a vacuum in the combustion chamber or decreasing engine speed, do not effectively contribute to increasing airflow pressure in the same manner. Instead, they could have the opposite effect or be irrelevant to the function of the centrifugal compressor. The correct choice accurately captures the fundamental operating principle of how a centrifugal compressor generates pressure.