US Patent 9387923 Gas turbine engine

A gas turbine engine (10) having an axial flow direction (X) therethrough in use. The gas turbine engine (10) comprises one or more rotor stages each comprising at least one rotor blade (120) having a root portion (122). The gas turbine engine (10) comprises a shroud (122) located upstream of one or more of the rotor stages relative to the axial flow direction (X). The shroud (122) defines a through passageway (128) extending between an inlet (130) and an outlet (132) which comprises a diffuser region (138). The diffuser region (138) is configured to reduce the axial velocity of air exiting the outlet (132) relative to air entering the diffuser portion (138) in use, wherein the outlet (132) is located such that air exiting the outlet (132) is directed substantially to the root portion (122) only of the rotor blades (120).