Which statement describes a disadvantage of a centrifugal-flow compressor?

Which statement describes a disadvantage of a centrifugal-flow compressor?

• A. Poor efficiency at low speeds
• B. Large frontal area for given airflow
• C. High maintenance cost due to seals
• D. Noise levels are excessive

Answer: (B)

A key issue with centrifugal-flow compressors is the size of the intake opening needed to move a given amount of air. In a centrifugal design, air enters axially, is accelerated by a radial impeller, and then diffused to higher pressure in a volute. To capture and diffuse that flow effectively for the same mass flow, the housing and inlet area must be relatively large, resulting in a noticeably larger frontal area than an axial-flow compressor doing the same job. That bulk affects installation, increasing nacelle diameter, drag, and weight, which is why this configuration is less compact for the same airflow. Despite this drawback, centrifugal compressors offer advantages like simple, robust construction and good surge margins, which is why they’re still used in certain engines. However, the large frontal area required for the same airflow remains their primary disadvantage.

A key issue with centrifugal-flow compressors is the size of the intake opening needed to move a given amount of air. In a centrifugal design, air enters axially, is accelerated by a radial impeller, and then diffused to higher pressure in a volute. To capture and diffuse that flow effectively for the same mass flow, the housing and inlet area must be relatively large, resulting in a noticeably larger frontal area than an axial-flow compressor doing the same job. That bulk affects installation, increasing nacelle diameter, drag, and weight, which is why this configuration is less compact for the same airflow.

Despite this drawback, centrifugal compressors offer advantages like simple, robust construction and good surge margins, which is why they’re still used in certain engines. However, the large frontal area required for the same airflow remains their primary disadvantage.