The performance of a ramjet engine is typically characterized by key parameters that assess its efficiency and effectiveness in generating thrust. The performance of a ramjet engine can be evaluated using various metrics, including specific thrust, thermal efficiency, and overall thrust.
- The thermal efficiency of a ramjet engine represents how effectively it converts the heat energy of combustion into useful thrust. It is defined as the ratio of useful work done (thrust) to the heat input.
Formula for thermal efficiency (ηth):
Where:
- ηth is the thermal efficiency (dimensionless).
- T is the thrust generated by the engine (in Newtons, N).
- ṁ is the air mass flow rate (in kilograms per second, kg/s).
- V is the flight velocity of the vehicle (in meters per second, m/s).
- Qc is the heat input to the engine (in Joules, J).