Which is a disadvantage of a centrifugal-flow compressor?

• A. Low efficiency
• B. High cost
• C. Simple construction
• D. Large frontal area for given airflow

Answer: (D)

In a centrifugal-flow compressor, air is drawn in axially and then accelerated outward by the impeller into a diffuser and volute. To move a given amount of air, the cross-sectional area at the compressor’s inlet front must be large enough, which means the frontal area grows with the required flow. Achieving that flow often requires a large impeller diameter and diffuser/volute size, so the overall frontal area of the compressor package becomes quite large.

That large frontal area creates packaging and aerodynamic challenges on aircraft, making the engine nacelle bigger and more drag-prone for the same airflow. While centrifugal compressors can be simple and robust, and can perform well at certain pressure ratios, the need for a large frontal area for a given airflow is a defining disadvantage in many applications.