US5169288A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low noise fan assembly
Assignee: General Electric Co
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Filing: 1991-09-06
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Granted: 1992-12-08
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Expires: 2011-09-06
Abstract
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.
Inventors
- 👤 Philip R. Gliebe
- 👤 Patrick Y. S. Ho
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 08:23
CPC Classifications
F; F02; F02C; F02C7/00; F02C7/04; F02C7/045; F05; F05D; F05D2220/00; F05D2220/30; F05D2220/32; F05D2220/327
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
140 words
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.
Claim 2
Dependent Claim
140 words
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.
Claim 3
Dependent Claim
21 words
A fan assembly according to claim 1 wherein said cut-off ratio at said two harmonic numbers n has a maximum value.
Claim 4
Dependent Claim
15 words
A fan assembly according to claim 1 wherein said two harmonic numbers n are consecutive.
Claim 5
Dependent Claim
17 words
A fan assembly according to claim 3 wherein said two consecutive harmonic numbers are n=2 and n=3.
Claim 6
Dependent Claim
23 words
A fan assembly according to claim 4 wherein said vane number V divided by said blade number B is equal to about 2.4.
Claim 7
Dependent Claim
20 words
A fan assembly according to claim 5 wherein said cut-off ratio at said harmonic number n=1 is less than 1.0.
Claim 8
Dependent Claim
21 words
A fan assembly according to claim 6 wherein said blade number B is 22 and said vane number V is 54.
Claim 9
Dependent Claim
45 words
A fan assembly according to claim 7 wherein: said cut-off ratio is proportional to nB/|m| and tip speed mach number of said fan blades relative to flow speed mach number of said air through said duct; m=nB-kV; and k is a positive or negative integer.
Claim 10
Dependent Claim
15 words
A fan assembly according to claim 1 wherein said two harmonic numbers n are non-consecutive.
Claim 11
Dependent Claim
16 words
A fan assembly according to claim 9 wherein said two harmonic numbers are n=1 and n=3.
Claim 12
Dependent Claim
23 words
A fan assembly according to claim 10 wherein said vane number V divided by said blade number B is equal to about 1.5.
Claim 13
Dependent Claim
16 words
A fan assembly according to claim 9 wherein said two harmonic numbers are n=2 and n=4.
Claim 14
Dependent Claim
23 words
A fan assembly according to claim 12 wherein said vane number V divided by said blade number B is equal to about 8/3.
Claim 15
Dependent Claim
55 words
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.
Claim 16
Dependent Claim
55 words
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.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-12-08 | 1996-06-08 | 1996-12-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-12-08 | 2000-06-08 | 2000-12-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-12-08 | 2004-06-08 | 2004-12-08 | $7700.00 | Window Closed / Lapsed |