Definition
A turbine engine compressor that uses both axial-flow and centrifugal-flow stages in series. Air first passes through one or more axial stages (where rotating blades push air straight back along the engine axis), then through a centrifugal stage (where an impeller flings air outward) before entering the combustion section.
Plain English
A turbine engine air compressor built in two parts: the first part squeezes air by pushing it straight back through rows of spinning blades, and the second part squeezes it again by spinning it outward. Combining the two methods raises the pressure more effectively than either method alone.
Context Anchor
Seen in turbine engine descriptions, especially when learning how small turbine engines move and compress air before burning fuel.
Derivation
Combination simply means two things working together. In this case, two compressor types -- axial and centrifugal -- are combined in one engine to get the benefits of both: the axial stages handle large volumes of air efficiently, and the centrifugal stage adds a strong final pressure rise in a compact space.
Why Pilots Care
Knowing your engine uses a combination compressor helps you understand its performance characteristics, why it tolerates certain operating conditions well, and why inlet care (FOD prevention, ice protection) matters for both the axial blades up front and the impeller behind them.
Intuition Check
Do not read “combination” as meaning a compressor used for several unrelated jobs. Here it means one compressor section built from two compressor designs working in sequence.
Example Sentence 1
The PT6 turboprop uses a combination compressor, with three axial stages followed by a single centrifugal stage.
Example Sentence 2
The combination compressor in the turboprop allowed higher pressure ratios while keeping the engine short and light.