Definition
A type of turbine engine compressor in which air flows in a straight line, parallel to the long axis of the engine, through a series of alternating rotating and stationary blade rows that progressively compress the air before it reaches the combustion section.
Plain English
A compressor that squeezes air by pushing it straight back through many sets of spinning and fixed blades, with each set raising the pressure a little more.
Context Anchor
Seen in turboprop engine descriptions, especially when explaining how air moves through a split-shaft or free-turbine engine.
Derivation
Axial comes from the Latin axis, meaning the central line something turns around. The name simply tells you the air flows along the engine's centerline, in contrast to a centrifugal compressor that flings air outward.
Why Pilots Care
Affects how efficiently the engine produces power and how much fuel it uses in turboprop aircraft.
Analogy
Think of a stack of fans inside a tube, each one pushing air a little harder into the next. By the time the air comes out the back end, it's been squeezed many times over.
Grounding Statement
Picture air entering the front of the engine and being pressed tighter as it travels straight rearward toward the burning section.
Intuition Check
Do not read “axial flow” as just “air moving somewhere.” Here it specifically means the air moves mainly along the engine’s centerline, not outward from the center.
Example Sentence 1
The PT6's gas generator section uses an axial flow compressor followed by a single centrifugal stage.
Example Sentence 2
In the split-shaft turboprop, the axial flow compressor is driven by the gas generator turbine.