| 摘要 |
A fan rotor arrangement comprises a fan rotor ( 24 ) and a plurality of fan blades ( 26 ). Each fan blade ( 26 ) comprises a root portion ( 36 ) and an aerofoil portion ( 38 ). Each aerofoil portion ( 38 ) has a leading edge ( 44 ), a trailing edge ( 46 ) and a tip ( 48 ). Concave pressure surface ( 50 ) and convex suction surface ( 52 ) extend from the leading edge ( 44 ) to the trailing edge ( 46 ) of each aerofoil portion ( 38 ). An annular wall ( 54 ) surrounds the fan rotor ( 24 ) and fan blades ( 26 ) and an inner surface ( 56 ) of the annular wall ( 54 ) has a circumferentially extending groove ( 58 ). The circumferentially extending groove ( 58 ) is arranged axially, or chordally, between the leading edges ( 44 ) and the trailing edges ( 46 ) at the tips ( 48 ) of the aerofoil portions ( 38 ) of the fan blades ( 26 ). The circumferentially extending groove ( 58 ) extends axially by at least half a wavelength of an unsteady pressure wave to provide a geometrically tuned cavity and additionally pressure loss to suppress axially upstream propagating unsteady pressure waves. This reduces vibrations of the fan blade ( 26 ).
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