What is a primary characteristic of a split-spool compressor?

A split-spool compressor is characterized by having two separate rotors that operate at different speeds for different pressure stages within the compressor. The dual rotor design allows each stage to be optimized for its specific operating conditions. Typically, one rotor operates at a higher speed for the high pressure stage and the other at a lower speed for the low pressure stage. This configuration improves efficiency and performance across a wider range of operating conditions, particularly in turbofan engines, where it contributes to better pressure rise and enhanced overall engine performance.

This characteristic is crucial because it allows the engine to maintain optimal airflow and pressure ratios throughout the operating envelope, thereby improving thrust and efficiency. The use of separate rotors also helps mitigate issues related to surge and stall that can occur in compressors with a single rotor design, enhancing the reliability and stability of the engine during various flight phases.