The thermal efficiency of a scramjet engine refers to the ratio of the useful work output to the heat energy input in the engine. In the context of a scramjet engine, which operates at supersonic speeds and relies on the combustion of fuel with atmospheric oxygen, the thermal efficiency is a crucial performance metric.
where:
- is the thermal efficiency,
- is the temperature of the exhaust gases,
- is the temperature of the incoming air, and
- is the temperature of combustion within the engine.