The “bypass ratio” of an aircraft engine is a critical parameter in aviation that measures the ratio of the mass of air that bypasses the engine core (flows around the engine) to the mass of air that passes through the engine core (flows into the engine and is combusted). It’s a key design parameter for turbofan engines, which are commonly used in modern aircraft. The bypass ratio is an important factor influencing engine efficiency, thrust, and fuel consumption.
The formula for calculating the bypass ratio () is straightforward:
- is the bypass ratio (dimensionless).
- is the mass flow rate of air bypassing the engine core (usually in kilograms per second or pounds per second).
- is the mass flow rate of air passing through the engine core (usually in kilograms per second or pounds per second).