Definition
A gas turbine combustion chamber design in which compressed air from the compressor enters the combustor and travels in the opposite direction to the eventual flow of hot gases through the engine. The air makes a U-turn inside the combustor, mixes with fuel and burns, then the hot gases reverse direction again to enter the turbine. This layout shortens the overall length of the engine by folding the combustion path back on itself.
Plain English
A combustion chamber shaped so the air flows backward through it before the burning gases turn around and head into the turbine. Folding the path this way lets engineers build a shorter, more compact engine.
Context Anchor
Seen in turbine engine descriptions, especially for compact turboprop and turboshaft engines.
Derivation
‘Reverse-flow’ simply describes the direction of airflow inside the combustor — opposite to the engine’s overall front-to-back gas flow. ‘Combustor’ comes from Latin combustus, ‘burned up,’ and refers to the section of the engine where fuel is burned.
Why Pilots Care
Knowing the engine has a reverse-flow combustor helps technicians understand the airflow path during inspection, troubleshooting hot-section issues, and interpreting maintenance manuals. It also explains why some small turbine engines are so much shorter than their straight-through counterparts.
Analogy
Imagine a hairpin turn in a hallway: air walks in one direction, turns around at the end, and walks back out the other way. Folding the path lets the whole hallway fit in half the space.
Intuition Check
“Reverse-flow” does not mean the engine produces reverse thrust or that the airplane is pushed backward. It means the airflow inside the combustor is turned back as part of the engine’s internal path.
Example Sentence 1
The PT6 turboprop uses a reverse-flow combustor, which is one reason the engine is so compact for its power output.
Example Sentence 2
Because it uses a reverse-flow combustor, the engine fits into a smaller nacelle without losing power output.