What is bypass ratio of turbine?

The bypass ratio of a turbine, particularly in the context of turbofan engines, is the ratio of the mass of air that bypasses the engine core to the mass of air that passes through the engine core. A higher bypass ratio indicates that more air is bypassed, typically resulting in greater fuel efficiency and lower noise levels. Turbofans with high bypass ratiOS are commonly used in commercial aviation, while those with lower ratiOS are found in military and supersonic aircraft.