Patent US3820918A successfully refreshed from Google Patents.
US3820918A
Expired / Lapsed
US
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Supersonic fan blading
Assignee: N A S A
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Filing: 1972-01-21
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Granted: 1974-06-28
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Expires: 1992-01-21
Abstract
Abstract Radially extending rotor blades are disposed on a hub to form a supersonic propulsion fan for a turbofan engine. The peripheral spacing of the blades is such as to avoid forming a channel or passageway between adjacent blades. Each blade has a flat trailing surface extending from the leading edge at least as far to the rear as to cause any pressure waves which might originate on the blade surface to strike the leading surface of the following blade rather than propagate upstream of the blade row. The flat trailing surface of each blade makes an angle with the axis of rotation such that the blade is parallel to a gas inflow into the blades.
Inventors
- 👤 A Goldstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 19:39
CPC Classifications
F; F04; F04D; F04D29/00; F04D29/26; F04D29/32; F04D29/321; F04D21/00; F05; F05D; F05D2240/00; F05D2240/20; F05D2240/30; F05D2240/302
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
106 words
A turbofan comprising: a plurality of blades extending radially from a hub, each blade, for any portion thereof traveling more than 1.3 times sonic speed, having a trailing surface flat over a sufficient length that any pressure wave emanating there shall be intercepted by the following blade and reflected downstream of the rotor, a leading edge wedge having an angle sufficiently small to permit attached bow waves, said leading edge wedge having a curved surface, a trailing edge wedge, and sufficiently large blade spacing relative to the blade chord to avoid interblade flow channels and choking flow, said blade being of constant thickness between said wedges.
Claim 2
Dependent Claim
106 words
A turbofan comprising: a plurality of blades extending radially from a hub, each blade, for any portion thereof traveling more than 1.3 times sonic speed, having a trailing surface flat over a sufficient length that any pressure wave emanating there shall be intercepted by the following blade and reflected downstream of the rotor, a leading edge wedge having an angle sufficiently small to permit attached bow waves, said leading edge wedge having a curved surface, a trailing edge wedge, and sufficiently large blade spacing relative to the blade chord to avoid interblade flow channels and choking flow, said blade being of constant thickness between said wedges.
Claim 3
Dependent Claim
17 words
The structure of claim 1 wherein the leading edge wedge angle is between about 6* to 12*.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |