6a746864_Jet_engine___Engineering__Type
[Description] Power tapped off exhaust used to drive bypass fan [Advantages] Quieter due to greater mass flow and lower total exhaust speed, more efficient for a useful range of subsonic airspeeds for same reason [Disadvantages] Greater complexity (additional ducting, usually multiple shafts), large diameter engine, need to contain heavy blades. More subject to FOD and ice damage. Different degrees of bypass are possible - this is the design most commonly used on commercial airliners [Type] 
Turbofan
Jet engine - Engineering
Type