US3830450A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual purpose circulation control airfoil
Assignee: United States Department of the Navy
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Filing: 1972-12-15
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Granted: 1974-08-20
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Expires: 1992-12-15
Abstract
Abstract A dual purpose circulation control airfoil is designed for operation at high speeds in the vicinity of transonic speed and for low speed applications such as landing speeds. A blunt trailing edge possesses a varying radius of curvature to comprise a high speed and low speed coanda surface. For high speed operation, air is blown from a slot over the high speed surface, moving upper surface stagnation point further aft and increasing lift. At low speed operation air is blown over the low speed surface to produce high lift for low landing speeds. In addition, a surface forward of the blunt edge is provided for supersonic expansion in transonic flight.
Inventors
- 👤 R Williams
- 👤 R Englar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:48
CPC Classifications
B; B64; B64C; B64C3/00; B64C3/10; B64C3/14; B64C3/141
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
226 words
A dual purpose circulation control airfoil having a trailing edge and including a trailing edge blowing slot for circulation control blowing over a blunt tail surface; said blunt tail surface comprising a high speed coanda surface for receiving supersonic circulation control blowing from said slot and a low speed coanda surface for receiving subsonic circulation control blowing from said slot; wherein said high speed coanda surface has a first radius of curvature, is adjacent said slot and extends aft of said slot where it merges into said low speed coanda surface, said low speed coanda surface having a second radius of curvature and extending aft of said high speed coanda surface and merging into the lower surface of said airfoil; said first radius of curvature being larger than said second radius of curvature; whereby during supersonic circulation control blowing over said high speed coanda surface the supersonic air flow discharged from said blowing slot remains at least partially attached to said high speed surface so as to relocate the stagnation point further aft on the airfoil and inCrease lift during high speed flight in the vicinity of transonic speeds; and during subsonic circulation control blowing the subsonic airflow discharged from said slot remains attached to said high speed and said low speed coanda surface and detaches at a point on the under surface of the airfoil.
Claim 2
Dependent Claim
226 words
A dual purpose circulation control airfoil having a trailing edge and including a trailing edge blowing slot for circulation control blowing over a blunt tail surface; said blunt tail surface comprising a high speed coanda surface for receiving supersonic circulation control blowing from said slot and a low speed coanda surface for receiving subsonic circulation control blowing from said slot; wherein said high speed coanda surface has a first radius of curvature, is adjacent said slot and extends aft of said slot where it merges into said low speed coanda surface, said low speed coanda surface having a second radius of curvature and extending aft of said high speed coanda surface and merging into the lower surface of said airfoil; said first radius of curvature being larger than said second radius of curvature; whereby during supersonic circulation control blowing over said high speed coanda surface the supersonic air flow discharged from said blowing slot remains at least partially attached to said high speed surface so as to relocate the stagnation point further aft on the airfoil and inCrease lift during high speed flight in the vicinity of transonic speeds; and during subsonic circulation control blowing the subsonic airflow discharged from said slot remains attached to said high speed and said low speed coanda surface and detaches at a point on the under surface of the airfoil.
Claim 3
Dependent Claim
105 words
The airfoil of claim 1, wherein: said high speed coanda surface is curved so as to maintain attachment of the supersonic air flow discharged from said slot according to the following relationship within the ranges given: 0 < h/R 0.01 0<C Mu 0.03 (for M Infinity >0.5) Pt/P >1.5 0.02 <R/c <0.10 where h is the height of the slot; R is the radius of curvature of the high speed coanda surface; Pt is the slot duct total pressure; P is the exit static pressure; C Mu is the blowing momentum coefficient; M Infinity is the free stream Mach number; c is the chord length.
Claim 4
Dependent Claim
62 words
The airfoil of claim 2, wherein: said low speed coanda surface is curved so as to maintain attachment of the subsonic air flow discharged from said slot according to the following relationship within the ranges given: 0 <h/r 0.05 0 <C Mu 0.20 1.0 <Pt/P 1.5 0.01 <r/c 0.04 where r is the radius of curvature of said low speed coanda surface.
References Cited (Backward Citations)
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US2885160A
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US3016213A
Cited
US2939650A
Cited
US3045947A
Cited
US3168997A
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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) | 1977-08-19 | 1978-02-18 | 1978-08-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-19 | 1982-02-18 | 1982-08-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-19 | 1986-02-18 | 1986-08-20 | $7700.00 | Window Closed / Lapsed |