What are the advantages of a turbofan engine?
Because the fuel flow rate for the core is changed only a small amount by the addition of the fan, a turbofan generates more thrust for nearly the same amount of fuel used by the core. This means that a turbofan is very fuel efficient. In fact, high bypass ratio turbofans are nearly as fuel efficient as turboprops.
Why do planes burn more fuel at lower altitudes?
Jet engines are more efficient at higher altitudes because the cold and less dense air at this altitude efficiently maximizes fuel burn. Thus, the pilot is able to fly with optimum cruise speed at high-altitudes with the best fuel economy.
Why are turbofan engines quieter than jet engines?
Turbojet engine noise is predominately jet noise from the high exhaust velocity, therefore turbofan engines are significantly quieter than a pure-jet of the same thrust, and jet noise is no longer the predominant source. Turbofan engine noise propagates both upstream via the inlet and downstream via the primary nozzle and the by-pass duct.
Why are turbofan engines good for supersonic speeds?
A higher BPR provides a lower fuel consumption for the same thrust. If all the gas power from a gas turbine is converted to kinetic energy in a propelling nozzle, the aircraft is best suited to high supersonic speeds.
What happens to an engine at high altitude?
Just throttling down can already cause the ignition to stop at high altitude. If a flame-out occurs, the engine cools down quickly and a restart at a lower altitude might not be possible. Turbofans suitable for high altitude operations use special measures to stabilize the flame.
What is the difference between a gas turbine and a turbofan?
The word turbofan is a portmanteau of turbine and fan: the turbo portion refers to a gas turbine engine which achieves mechanical energy from combustion, and the fan, a ducted fan that uses the mechanical energy from the gas turbine to accelerate air rearwards.