In a split-spool compressor, which rotor configuration is described?

In a split-spool compressor, which rotor configuration is described?

• A. One rotor with six stages
• B. Three rotors with five stages
• C. A single rotor with no stages
• D. Two rotors with nine and seven stages

Answer: (D)

Split-spool compressors use two concentric rotors on separate shafts, each carrying its own set of compression stages, so the spools can run at different speeds to optimize performance across operating conditions. The described setup—one rotor with nine stages and the other with seven stages—fits this arrangement, providing the needed overall compression while allowing each spool to operate efficiently in its respective flow and pressure range. The other options either imply a single rotor, more than two rotors, or a rotor with no stages, which don’t describe a split-spool configuration.

Split-spool compressors use two concentric rotors on separate shafts, each carrying its own set of compression stages, so the spools can run at different speeds to optimize performance across operating conditions. The described setup—one rotor with nine stages and the other with seven stages—fits this arrangement, providing the needed overall compression while allowing each spool to operate efficiently in its respective flow and pressure range. The other options either imply a single rotor, more than two rotors, or a rotor with no stages, which don’t describe a split-spool configuration.