Which compressor type is more efficient at lower N1?

The 3-stage axial compressor is more efficient at lower rotational speeds (N1) due to its design, which allows for smoother airflow and less energy loss under these conditions. Axial compressors operate by moving air through a series of rotating and stationary blades, and they are particularly effective at producing high pressure ratios at lower flow rates. As a result, their performance remains strong when the engine speed is reduced, making them an excellent choice for applications that require optimal efficiency at lower N1.

In contrast, centrifugal compressors are generally tailored for applications that demand high pressure and flow rates, excelling at higher rotational speeds. At lower speeds, they can experience efficiency loss due to their design characteristics. In this sense, while both compressors have their advantages, the axial compressor's ability to maintain efficiency at lower speeds sets it apart and makes it more suitable in situations where lower N1 is a factor.