The Rolls-Royce RB.211 is a family of high-bypass turbofan engines that has been widely used in various commercial and military aircraft. The thermal efficiency of a turbofan engine is a measure of how effectively the engine converts the chemical energy in fuel into useful work, primarily in the form of thrust. The thermal efficiency is defined as the ratio of the useful work output to the energy input from burning the fuel.
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.