Low noise fan assembly
AssigneeGeneral Electric Company
InventorsPhilip R. Gliebe, Patrick Y. S. Ho
Life of this patent
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Abstract
A gas turbine engine rotor assembly such as a fan or compressor includes rotor blades spaced axially from stator vanes inside an annular duct. The number of vanes is selected for a predetermined number of blades for obtaining substantially equal values of a cut-off ratio for at least two blade passing frequency harmonics for reducing spinning mode noise from the duct.
Claims14
A gas turbine engine fan assembly comprising:
- a number B of circumferentially spaced rotor blades;
- a number V of circumferentially spaced stator vanes spaced axially from said blades;
- an annular duct surrounding said blades and said vanes and having an inlet for receiving air and an outlet for discharging at least a portion of said air upon compression by said blades, said compressed air generating spinning mode tones each of which propagates above a respective cut-off ratio of 1.0 and decays below said cut-off ratio of 1.0 at a plurality of respective blade passing frequency harmonic numbers n;
- and
- said vane number V relative to said blade number B being effective for obtaining substantially equal values of said cut-off ratio for at least two of said harmonic numbers n, said two harmonic numbers n having a product greater than 2.
A gas turbine engine fan assembly comprising a number B of circumferentially spaced rotor blades, a number V of circumferentially spaced stator vanes spaced axially from said rotor blades, and a ratio V/B of said number of vanes V divided by said number of blades B being selected from the group including 2.4, 1.5and 8/3.
Dependencies are inferred from the claim text.