FAA Aviation Mechanic Powerplant (AMP)Turbine EnginesMedium
Which characteristic is a significant advantage of a centrifugal-flow compressor compared to an axial-flow compressor stage of similar diameter?
- AIt maintains higher efficiency at very high airflow rates
- BIt has a smaller frontal area for the same airflow
- CIt produces a much higher pressure ratio per stage
- DIt allows many stages to be added easily for higher overall ratios
Show answer & explanationAnswer & explanation
Correct answer: C. It produces a much higher pressure ratio per stage
A single centrifugal compressor stage can produce a pressure ratio of about 4:1, far exceeding the roughly 1.2:1 ratio typical of a single axial-flow stage, making it advantageous where fewer stages and simpler construction are desired.
Why the other options are wrong
- A. Axial compressors are generally more efficient at high airflow rates.
- B. Centrifugal compressors actually have a larger frontal area, which is a disadvantage.
- D. Axial compressors, not centrifugal, are easily staged for higher overall ratios.
Centrifugal vs Axial Compressor
Centrifugal compressors use radial impellers to achieve high pressure ratios per stage, while axial compressors use rows of rotating/stationary blades for efficient high-airflow, multi-stage compression.
- Centrifugal: ~4:1 pressure ratio per stage, rugged, larger frontal area
- Axial: ~1.2:1 per stage, smaller frontal area, higher efficiency at high airflow
- Axial preferred for large high-bypass turbofans
Memory trick: 'Centrifugal = Compact Kick' - one big pressure jump per stage