Propulsion Efficiency & Turbofan
- The propulsion efficiency increases as the velocity ratio is increased.
- It reaches a maximum at v=1 and h=1. No lost kinetic energy but also no thrust since V1=V6.
- It also suggests that in order to increase the propulsion efficiency one would like to operate at relatively low jet nozzle velocity.
- In order to avoid the loss of thrust, the mass flow rate has to be increased.
- Consequently, turbofan engine is a more efficiency engine as compared to the turbojet engine since the fan can induce large amount of the propellant into the engine and can operate at a relatively low jet exhaust speed.