The thermal efficiency of a turbojet engine is a measure of how effectively it converts the chemical energy in fuel into useful work in the form of thrust. It is defined as the ratio of the useful work output (thrust) to the energy input from burning the fuel.
The thermal efficiency is a crucial parameter in assessing the overall performance of a turbojet engine. It indicates how well the engine is able to convert the chemical energy in the fuel into useful work, with higher thermal efficiency values corresponding to more efficient engines.
The thermal efficiency is expressed mathematically as:
where:
- is the thermal efficiency,
- is the thrust produced by the engine,
- is the jet velocity,
- ṁf is the mass flow rate of fuel,
- is the specific enthalpy of the fuel.