Gas turbine ducted fan engine - has multistage axial flow compressor with initial stage over-pressurising, with excess fluid discharged via variable area ports into duct

摘要

The fan ducting is for a multi stage axial flow compressor (15) of a gas turbine engine. The upstream stage (30) of the compressor produces a higher pressure ratio than required by the remainder of the staging. The excess fluid, due to the'over-compression' is discharged through ports (29) in the compressor casing to enter the fan duct of the engine. The ports may be circumferential slot in the housing. The shell of the casing is movable on a linkage mechanism allowing the discharge port's cross-sectional area to be varied.