Vortex alleviating wing tip
First Claim
1. In a wing of finite spanwise extent for producing lift or thrust by virtue of a dynamic flow of fluid over oppositely disposed upper and lower wing surfaces, each of the surfaces extending chordwise from a leading to a trailing edge, an improved tip at the spanwise termination of the wing for bringing about a controlled mergence of the fluid flowing over the upper and lower surfaces at different pressure levels comprising:
- contoured surface portions joined with the upper and lower wing surfaces and blending smoothly into the upper and lower wing surfaces without abrupt changes in the spanwise direction, the contoured surface portions forward of the chord point of maximum thickness being convexedly rounded without concave portions at any spanwise section in the forward part of the tip and convergent along the outboard edge at large obtuse angles generally at 180 degrees to smoothly interconnect the forward parts of the upper and lower wing surfaces, and aft of the chord point of maximum thickness, the contoured surface portions including a convex lower portion bending gradually upwardly in the spanwise direction with substantially uniform curvature from the junction of the tip and lower wing surface to the outboard edge and joined with a concave upper portion also bending gradually upward in the spanwise direction with substantially uniform curvature from the junction of the tip and upper wing surface to define a gradually tapered, sharp, upwardly swept edge portion and bring about a controlled mergence of the flows above and below the wings, the gradually bending upper and lower portions approaching one another at the outboard edge at acute angles progressively decreasing from the chord point of maximum thickness to the trailing edge, and forming a sharply angled outboard edge without substantial curvature of the surfaces in the chordwise direction to reduce differential pressure and to precipitate vortices generated by the confluence of flows over the upper and lower surfaces with immediate separation at the spanwise termination of the wing.
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Abstract
A wing tip is contoured and shaped to bring about a controlled mergence of fluid flows across the upper and lower wing surfaces and alleviation of the resulting vortex when the wing is producing lift or thrust. Control through geometry of the wing tip can be augmented by discharging fluid into the merging flows which weakens the strength of the vortex and results in more rapid dissipation in the wake of an aircraft. Additionally, the origin of the vortex is prevented from migrating inboard of the wing tip which improves overall wing efficiency.
62 Citations
24 Claims
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1. In a wing of finite spanwise extent for producing lift or thrust by virtue of a dynamic flow of fluid over oppositely disposed upper and lower wing surfaces, each of the surfaces extending chordwise from a leading to a trailing edge, an improved tip at the spanwise termination of the wing for bringing about a controlled mergence of the fluid flowing over the upper and lower surfaces at different pressure levels comprising:
- contoured surface portions joined with the upper and lower wing surfaces and blending smoothly into the upper and lower wing surfaces without abrupt changes in the spanwise direction, the contoured surface portions forward of the chord point of maximum thickness being convexedly rounded without concave portions at any spanwise section in the forward part of the tip and convergent along the outboard edge at large obtuse angles generally at 180 degrees to smoothly interconnect the forward parts of the upper and lower wing surfaces, and aft of the chord point of maximum thickness, the contoured surface portions including a convex lower portion bending gradually upwardly in the spanwise direction with substantially uniform curvature from the junction of the tip and lower wing surface to the outboard edge and joined with a concave upper portion also bending gradually upward in the spanwise direction with substantially uniform curvature from the junction of the tip and upper wing surface to define a gradually tapered, sharp, upwardly swept edge portion and bring about a controlled mergence of the flows above and below the wings, the gradually bending upper and lower portions approaching one another at the outboard edge at acute angles progressively decreasing from the chord point of maximum thickness to the trailing edge, and forming a sharply angled outboard edge without substantial curvature of the surfaces in the chordwise direction to reduce differential pressure and to precipitate vortices generated by the confluence of flows over the upper and lower surfaces with immediate separation at the spanwise termination of the wing.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 23)
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8. A lift-producing wing of limited span for reducing induced drag and vortex strength comprising:
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upper and lower wing surfaces joined forwardly at a leading edge and aft at a trailing edge, the wing surfaces also extending spanwise and having shaped upper and lower terminal portions projecting in a gradually tapered fashion outwardly to a spanwise flattened tip and joined with one another at the tip along a sharply angled outer edge of the wing aft of the chord point of maximum thickness to permit fluid flows above and below the wing surfaces to merge at the angled outer edge, the angled outer edge of the wing extending forward from a point at the trailing edge at least as far outboard on the wing as any other point on the wing, and the terminal portions being shaped with uniform, curvatures in the spanwise direction between the wing and the outer edge, one of the portions having a concave curvature and the other having a convex curvature; and aperture means located at the angled outer edge of the wing and defining an opening for discharging fluid outwardly and rearwardly in the direction of lift producing fluid flowing from below the wing into merging flows from below and above the wing surfaces as the wing develops lift or thrust to thereby weaken wing tip vortices and shift the vortex origins outboard of the wing. - View Dependent Claims (9, 10, 11, 12, 13)
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- 14. An aircraft comprising a main body and an airfoil having upper and lower surfaces for producing lift when the airfoil is moved through air, the airfoil being connected at one end with the body of the craft and having an opposite, outer end from which fluid dynamic vortices emanate due to the mergence of fluid flows from above and below the foil while the foil is producing lift, the outer end of the foil projecting spanwise and gradually tapering to a sharply angled outer edge aft of the chord point of maximum thickness for vortex precipitation which edge in planform is located effectively no closer to the main body at the trailing edge of the foil than at the midchord region to prevent inward migration of the vortex origins and to reduce the induced drag, the gradual tapering being accompanied by substantially no curvature of the surfaces in the chordwise direction between the chordpoint of maximum thickness and the trailing edge to correspondingly reduce the differential pressure between the upper and lower surfaces and reduce the strength of the vortices produced thereby, and means defining an outwardly and rearwardly directed conduit at the projecting, sharply angled edge for discharging a fluid into the mergence of the fluid flows to dissipate the fluid dynamic vortices which are produced.
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20. In a craft having lift generating foils extending from a central body laterally outboard at each side of the craft, improved aerodynamic tips at the outboard ends of the foils comprising:
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a rounded tip at the outboard end of each lift-generating foil; means at the outboard end of each lift-generating foil for discharging fluid alternatively outboard tangentially of the foil and over the rounded tip for vortex alleviation, or tangentially inboard over the foil into the region of vortex origins to improve vortex generation; fluid supply means connected with the discharging means for providing the fluid to be discharged inboard and outboard; and fluid control means connected with the discharging means for controlling the discharging of fluid and directing the fluid alternatively outboard or inboard over the foil. - View Dependent Claims (21, 22)
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24. An aircraft comprising a main body and an airfoil having upper and lower surfaces for producing lift when the airfoil is moved through air, the airfoil being connected at one end with the body of the craft and having an opposite, outer end from which fluid dynamic vortices emanate due to the mergence of fluid flows from above and below the foil while the foil is producing lift, the outer end of the foil projecting spanwise and having upper and lower surfaces meeting substantially at 180 degrees without concave portions at any spanwise section in the part of the tip forward of the chord point of maximum thickness, and aft of the chord point of maximum thickness gradually tapering to a sharply angled edge for vortex precipitation which edge in planform is located effectively no closer to the main body at the trailing edge of the foil than at the midchord region to prevent inward migration of the vortex origins and to reduce the induced drag, the gradual tapering providing substantially no curvature of the surfaces in the chordwise direction aft of the chordpoint of maximum thickness to correspondingly reduce the differential pressure between the upper and lower surfaces and reduce the strength of the vortices produced thereby.
Specification