A turbofan's a type of aircraft engine consisting of a ducted fan which's powered by a gas turbine. Part of the airstream from the ducted fan passes through the gas turbine core, providing oxygen to burn fuel to create power. However, most of the air flow bypasses the engine core, and's accelerated by the fan blades in much the same manner as a propeller. The combination of thrust produced from the fan and the exhaust from the core's a more efficient process than other jet engine designs, res… (More on Turbofan)