Definition
A turbine engine compressor design that combines two compressor types in sequence: an axial-flow compressor (which moves air rearward through a series of rotating and stationary blades) followed by a centrifugal-flow compressor (which uses a spinning impeller to fling air outward). The combination produces higher pressure ratios than either type alone in a compact package, and is common in turboshaft and turboprop engines used in helicopters and small aircraft.
Plain English
A type of jet engine compressor that uses two stages stacked back-to-back. First, air passes through a set of fan-like blades that push it straight back. Then it hits a spinning disc that flings it outward to squeeze it even more before it reaches the burner section.
Context Anchor
Seen when reading about turbine engine compressor types and how air moves through the front section of a turbine engine.
Derivation
‘Centrifugal’ comes from Latin centrum (centre) and fugere (to flee) — literally ‘fleeing the centre,’ which is what air does when flung outward by the spinning impeller. ‘Axial’ comes from Latin axis (a central line) — the air moves along the engine’s central axis. The hyphenated name simply reflects that both flow patterns are used, one after the other.
Why Pilots Care
Engines using this design are common in the helicopter and light turboprop world, so pilots transitioning to turbine aircraft will often meet this term in their aircraft’s engine description and limitations.
Intuition Check
Do not read this as two separate engines. It describes one airflow path that uses both outward movement and straight-back movement inside the compressor.
Example Sentence 1
The Bell 206 helicopter uses a centrifugal-axial flow compressor in its turboshaft engine.
Example Sentence 2
During preflight the pilot reviews the centrifugal-axial flow compressor performance data in the engine log.