Centrifugal air flow control

• US 6,203,269 B1
• Filed: 02/25/1999
• Issued: 03/20/2001
• Est. Priority Date: 02/25/1999
• Status: Expired due to Term

• Current Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation), United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Lord, Wesley K., Lorber, Peter F.
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): WOO, RICHARD SUKYOON
• Application Number:
  US09/257,483
• Time in Patent Office: 754 Days
• Field of Search: 415/115, 415/119, 415/914, 416/91, 416/90.A, 416/90.R, 244/207
• US Class Current: 415/115
• CPC Class Codes: B64C 11/18 Aerodynamic features
• CPC Class Codes: B64C 21/025 for simultaneous blowing and sucking
• CPC Class Codes: B64C 2230/20 by passively inducing fluid flow, e.g. by means of a pressure difference between both ends of a slot or duct
• CPC Class Codes: B64C 2230/28 at propeller or rotor blades
• CPC Class Codes: B64C 27/467 Aerodynamic features
• CPC Class Codes: F01D 5/145 Means for influencing boundary layers or secondary circulations for compressors F04D29/68
• CPC Class Codes: F04D 29/682 by fluid extraction
• CPC Class Codes: F04D 29/684 by fluid injection
• CPC Class Codes: Y02T 50/10 Drag reduction
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y10S 415/914 Device to control boundary layer

Abstract

Blades, including helicopter rotor blades, gas turbine engine fan blades, air moving machinery fan blades, and the like, have an air inlet near the hub of the blade, which may be on the pressure side of the blade and/or near the leading edge or trailing edge nearer the tip of the blades, with an air plenum between the air inlet and the slots, whereby air is forced into the inlet, through the plenum and out of the slots into the flow adjacent the blades. The slots may be through the suction surface of the blade, typically near the boundary layer separation point, so that air flowing out of the slots into the boundary layer of the suction surface of the blade, thereby delay or prevent the onset of boundary layer separation, or to reduce supersonic shock. The inlet may be near the trailing edge of the blade, near the root, adjacent to the air inlet of the core of a jet engine, to suction off air and reduce fan wake blockage at the core inlet. The slots may be through the pressure surface adjacent the blade tip edge of fan blades to reduce blade tip leakage effects.

Claims

1. A helicopter rotor blade comprising:

a hub, a leading edge, a tip, a root, a pressure surface and a suction surface;

an air inlet extending through the pressure surface of said blade near said hub;

a plurality of slots extending through the suction surface of said blade closer to said tip than to said hub near the boundary layer separation point of said suction surface; and

a plenum within said blade extending from said air inlet to said slots. whereby as said blade rotates, air is forced into said air inlet and driven by centrifugal force along said plenum to exit from said slots into the flow of air adjacent said blade.

2. A blade according to claim 1 wherein:

said inlet is disposed near the leading edge of said blade.

3. A blade according to claim 1 wherein said air inlet extends through the pressure surface near the leading edge of said blade.

4. A blade which is part of the fan of an axial flow gas turbine engine having an air bypass duct, comprising:

a hub, a leading edge, a tip, a root, a pressure surface and a suction surface;

an air inlet extending through a surface of said blade near the trailing edge of said blade near the root of said blade;

one or more slots extending through a surface of said blade closer to said tip than to said hub; and

a plenum within said blade extending from said air inlet to said one or more slots, whereby as said blade rotates, air is forced into said air inlet and driven by centrifugal force along said plenum to exit from said one or more slots into the flow of air adjacent said blade.

5. A blade according to claim 4 wherein:

said one or more slots extend through the suction surface of said blade, air exiting from said slot into the boundary layer of said suction surface providing air particles with significant momentum flux into the boundary layer of said suction surface, thereby delaying or preventing boundary layer separation.

6. A blade according to claim 5 wherein said one or more slots are disposed near the boundary layer separation point of said blade.

7. A blade according to claim 5 wherein said slots inject air substantially tangentially into said boundary layer.

8. A blade according to claim 5 wherein:

said slots are disposed either (a) near or (b) downstream of the mid-chord point of said blade.

9. A blade according to claim 4 wherein said inlet extends through the suction surface of said blade.

10. A blade which is part of the fan of an axial flow gas turbine engine having an air bypass duct and a core, said blade comprising:

a hub, a leading edge, a tip, a root, a pressure surface and a suction surface;

an air inlet extending through a surface of said blade near the trailing edge of said blade adjacent to the air inlet of said core to reduce fan blade wake blockage, thereby to increase core flow capacity;

one or more slots extending through a surface of said blade closer to said tip than to said hub; and

a plenum within said blade extending from said air inlet to said one or more slots, whereby as said blade rotates, air is forced into said air inlet and driven by centrifugal force along said plenum to exit from said one or more slots into the flow of air adjacent said blade.

11. A blade according to claim 10 wherein said inlet extends through the suction surface of said blade.

12. A blade according to claim 10 wherein said one or more slots extends through the suction surface of said blade, air exiting from said slot into the boundary layer of said suction surface providing air particles with significant momentum flux into the boundary layer of said suction surface, thereby delaying or preventing boundary layer separation of the flow which will enter said bypass duct.

13. A blade according to claim 10 wherein said one or more slots is disposed near the tip edge of said blade.

14. A blade according to claim 10 wherein said one or more slots extend through the pressure surface along the tip edge of said blade.

15. A blade according to claim 10 wherein said one or more slots extends through said suction surface where supersonic shock occurs on said suction surface.

16. A blade according to claim 10 wherein said one or more slots extends through said suction surface either (a) near or (b) downstream of the mid-chord point of said blade.