What is the method of airflow in the centrifugal compressor of the APU?

The method of airflow in the centrifugal compressor of an Auxiliary Power Unit (APU) is characterized by circular flow around the impeller. In a centrifugal compressor, the impeller spins at high speeds, imparting energy to the air and increasing its velocity as it moves outward from the center of the impeller. This action creates a circular flow pattern as the air is thrown outwards due to centrifugal force.

The design of the centrifugal compressor encourages the air to enter the impeller at the center and then be expelled tangentially at high speed, which leads to a pressure increase. This process is crucial for the efficient function of the APU, as it generates the necessary compressed air or gas to power auxiliary systems.

Understanding this airflow pattern is essential for recognizing how centrifugal compressors function in various applications, particularly in aviation systems.