Definition
A two-stage airflow process inside a turbine engine compressor in which each stage first accelerates the air through rotating compressor blades, then diffuses (slows) it through stationary stator vanes, raising its pressure before it enters the next stage or the combustion chamber.
Plain English
Air is sped up by a spinning blade, then slowed down again in the next set of fixed blades. Slowing the air squeezes it, which raises its pressure. This pair of steps repeats through every stage of the compressor.
Context Anchor
Seen when studying how a fixed-shaft turboprop engine compresses air before burning fuel.
Derivation
Acceleration means speeding up; diffusion in fluid dynamics means spreading out and slowing down. Pairing the two names captures exactly what happens in each compressor stage: speed up, then slow down to gain pressure.
Why Pilots Care
This process allows the engine to deliver stable compressed air for combustion and power without needing variable geometry in the compressor.
Grounding Statement
Picture air entering the engine: moving blades speed it up, then fixed passages slow and spread it so it arrives tighter and higher-pressure where fuel will burn.
Intuition Check
Do not read this as the airplane accelerating and then slowing down. Here, acceleration and diffusion describe what happens to the air inside the engine.
Example Sentence 1
In a fixed-shaft turboprop, the acceleration/diffusion process repeats through each compressor stage to build the pressure needed for combustion.
Example Sentence 2
At high power the acceleration/diffusion process keeps airflow steady through the compressor stages.