What risk is associated with compressor surge?

Compressor surge is a phenomenon that occurs in centrifugal and axial compressors when the flow of gas through the compressor drops below a critical level, leading to a reversal of airflow. This reversal can cause significant damage to the compressor's internal components, including the impeller and the casing, if it is not controlled effectively.

In a surge condition, the compressor cannot maintain stable operation, which results in unstable flow rates that can lead to vibrations and mechanical failures. The airflow reversal creates turbulence, which further exacerbates the risk of damaging the compressor and can disrupt the overall system operation.

Other options present risks typically associated with compressor performance issues but do not directly relate to the critical nature of surge. For instance, while excessive noise and increased inlet temperature can occur due to other operational inefficiencies, they do not specifically identify the direct and immediate threat posed by compressor surge. Similarly, a reduction in fuel efficiency might be a consequence of various operational issues, but it is not the defining characteristic of surge behavior.