Definition
In a gas turbine engine, the ratio of the actual heat released by burning the fuel in the combustion chamber to the total heat that would be released if all of the fuel were burned completely. It is expressed as a percentage and indicates how thoroughly the combustor converts fuel into usable thermal energy.
Plain English
A measure of how well the engine's burner section turns fuel into heat. If every drop of fuel burned completely, efficiency would be 100%. In practice, a small amount of fuel does not burn fully, so the figure is slightly lower.
Context Anchor
Seen in turbine-engine performance, engine design, and maintenance discussions, especially when talking about fuel use, exhaust smoke, or engine heat output.
Derivation
Combustor comes from the Latin combustus, meaning 'burned up.' Efficiency comes from the Latin efficere, 'to accomplish.' Together the term describes how well the burning section accomplishes its job of releasing heat from the fuel.
Why Pilots Care
Lower efficiency increases fuel consumption and can raise turbine temperatures, shortening engine life and reducing range.
Grounding Statement
In a turbine engine, the combustor’s job is to burn fuel in fast-moving compressed air and release heat smoothly and completely.
Intuition Check
Combustor efficiency does not mean overall engine efficiency or how much thrust the engine produces. It means how completely the combustor burns the fuel and releases its heat.
Example Sentence 1
Modern turbine engines are designed with high combustor efficiency, meaning nearly all of the fuel sprayed into the combustion chamber is fully burned.
Example Sentence 2
A decline in combustor efficiency required higher fuel flow to maintain the same thrust on climb-out.