Bell-mouth Inlet Duct (gas Turbine Engine Component)

A form of convergent inlet air duct used to direct air into the inlet of a gas turbine engine. The area of a convergent duct gets smaller as the air flows into the engine. A bell-mouth inlet duct is extremely efficient, and is used where there is little ram pressure available to force the air into the engine. Bell-mouth ducts are used in engine test cells and on engines installed in helicopters.