Wingtip vortex drag reduction method using backwash convergence
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
B64C-023/06
B64D-027/02
F03D-001/06
출원번호
US-0505300
(2014-10-02)
등록번호
US-9776710
(2017-10-03)
발명자
/ 주소
Duke, John Hincks
출원인 / 주소
Duke, John Hincks
인용정보
피인용 횟수 :
0인용 특허 :
16
초록▼
A fuel efficient aircraft propulsion system comprises a wingtip mounted ducted pusher fan with convergent backwash and a skewed conical engine nacelle. The system both mitigates wingtip vortex drag and converts a portion of vortex energy into propulsion force and lift force. The forward-tapering nac
A fuel efficient aircraft propulsion system comprises a wingtip mounted ducted pusher fan with convergent backwash and a skewed conical engine nacelle. The system both mitigates wingtip vortex drag and converts a portion of vortex energy into propulsion force and lift force. The forward-tapering nacelle skews both downward and inward, so the lower nacelle surface is flush with the lower wing surface and the inboard nacelle surface does not alter flow over the upper wing surface. This firstly preserves lift at the outboard wing end. Secondly, air displacement by the nacelle accelerates flow only on the outboard and upper nacelle surfaces, and because the nacelle occupies the core of the nascent wingtip vortex, rotational air velocity is greatest on the upper nacelle surface. The resultant pressure drop on the upper nacelle surface contributes to aircraft lift. And because the nacelle surface tapers forward, this pressure drop does not exert backward-acting drag on the aircraft. Aft of the nacelle, the pusher fan hub surface conforms with the aft nacelle surface and tapers aft. Propulsion foils project from the forward portion of the pusher fan hub at an outward-aft angle, which directs convergent high pressure backwash flow along the aft tapering hub surface. This isolates aft-facing hub surfaces from drag-inducing vortex core pressure drop. Downstream fan backwash convergence then forms a central volume of high pressure flow where the low pressure trailing vortex core would otherwise develop. This is an efficient means to dissipate the cyclonic structure of the vortex, because vortex persistence requires low pressure core persistence. The direction of pusher fan rotation opposes the direction of wingtip vortex rotation as described in the prior art. This cross-flow interaction increases the effective power of the fan and also further counters vortex formation. An integral peripheral duct links the outer ends of the fan propulsion foils to provide thrust efficiency similar to that of a high bypass fanjet engine, but without the internal air friction within a bypass channel. In an alternative horizontal axis wind turbine embodiment, the same nacelle form supports secondary power-takeoff turbines mounted in high energy density flow at the turbine blade tips.
대표청구항▼
1. A method to reduce drag force from a lift-induced vortex at a free end of a lifting foil in a stream of a fluid during recovery of energy from the vortex, the method comprising: displacing the fluid radially outward with respect to the rotation axis of the vortex during inception of the vortex an
1. A method to reduce drag force from a lift-induced vortex at a free end of a lifting foil in a stream of a fluid during recovery of energy from the vortex, the method comprising: displacing the fluid radially outward with respect to the rotation axis of the vortex during inception of the vortex andangularly accelerating the fluid in both a radial direction towards the rotation axis of the vortex and a circumferential direction opposite to the vortex rotation direction,where the angular acceleration is reacting to one of either a propulsion fan with a set of outward-aft swept propulsion foils or a power generating turbine with a set of outward-forward swept power takeoff foils. 2. The method of claim 1 in which said radially outward fluid displacement is in the portion of vortex rotation with a component of movement in the foil lift direction. 3. The method of claim 1 in which said angular acceleration is in reaction to propulsion. 4. The method of claim 1 where the angular acceleration is reacting to the propulsion fan with the set of outward-aft swept propulsion foils and where the method of claim 1 is performed by: an aircraft wing with an inboard end and an outboard end, a forward leading edge and an aft trailing edge, and an upper low pressure surface and a lower high pressure surface,where flight motion of the wing causes formation of the lift-induced vortex at the outboard wing end,where the outboard wing end body projects into a nacelle body so that the vortex forms around the nacelle,where the nacelle tapers forward,where the nacelle taper skews so a lower nacelle surface is substantially tangent to the lower high pressure wing surface,where the nacelle taper also skews so an inboard nacelle surface is substantially tangent to a vertical longitudinal plane,a rotary engine contained within the nacelle,a propulsion hub of the propulsion fan that rotatably connects to the aft end of the nacelle substantially co-axial with the vortex,where the propulsion hub tapers aft,where the propulsion hub is driven by the engine in a direction opposing the vortex in flight,where the set of propulsion foils of the propulsion fan projects from the propulsion hub,where each propulsion foil has a high pressure surface and a low pressure surface, andwhere the high pressure propulsion foil surfaces are pitched to face axially aft, radially inwards towards the propulsion hub rotation axis, and circumferentially opposite the direction of vortex rotation. 5. The method of claim 4 in which the aft circumferential surface of the nacelle is substantially tangent to the forward circumferential surface of the propulsion hub. 6. The method of claim 4 in which the angle between the span axes of the propulsion foils and a transverse plane is between 15 and 40 degrees. 7. The method of claim 4 in which the angle between the direction of the propulsion foils' backwash and a freestream direction is between 10 and 35 degrees. 8. The method of claim 4 further comprising a streamlined circular propulsion duct connecting to the peripheral propulsion foil ends. 9. The method of claim 8 in which the propulsion duct chord tapers inward-aft towards the propulsion hub rotation axis. 10. The method of claim 9 in which the angle between the propulsion duct chord and a freestream direction is between 1 and 5 degrees. 11. The method of claim 1 where the angular acceleration is reacting to the power generating turbine with the set of outward-forward swept power takeoff foils and where the method of claim 1 is performed by: a radial primary turbine blade with an axis of rotation substantially parallel to a free stream fluid flow, an inner end and an outer end, a leading edge and a trailing edge, and an upstream high pressure surface and a downstream low pressure surface,where power generating rotary motion of the turbine blade causes formation of the lift-induced vortex at the outer turbine blade end,where a forward direction is substantially into the fluid flow relative to the rotating outer turbine blade end,where an aft direction is opposite the forward direction,where the outer turbine blade end body projects into a nacelle body so that the vortex forms around the nacelle,where the nacelle tapers forward,where the nacelle taper skews so an upstream nacelle surface is substantially tangent to the primary turbine blade's high pressure surface at the primary turbine blade's outer end,where the nacelle has an inner surface facing towards the primary turbine blade's rotation axis,where the nacelle taper also skews so the inner nacelle surface is substantially tangent to a cylinder in space that is concentric with the primary turbine blade's rotation axis,a power takeoff hub of the power generating turbine that rotatably connects to the aft end of the nacelle substantially co-axial with the vortex,where the power takeoff hub tapers aft,where the set of power takeoff foils of the power generating turbine projects from the power takeoff hub,where each power takeoff foil has a high pressure surface and a low pressure surface,where the power takeoff foil high pressure surfaces are pitched to face axially forward on the power takeoff hub, radially inwards towards the power takeoff hub rotation axis, and circumferentially opposite the direction of vortex rotation, anda rotary power generator contained within the nacelle that is driven by the power takeoff hub. 12. The method of claim 11 in which the aft circumferential surface of the nacelle is substantially tangent to the forward circumferential surface of the power takeoff hub. 13. The method of claim 11 in which the angle between the span axes of the power takeoff foils and a transverse nacelle plane is between 15 and 40 degrees. 14. The method of claim 11 in which the angle between the direction of the power takeoff foils' backwash and a direction of relative flow of the fluid when the primary turbine blade is turning is between 10 and 35 degrees. 15. The method of claim 11 further comprising a streamlined circular power takeoff duct connecting to the peripheral power takeoff foil ends. 16. The method of claim 15 in which the power takeoff duct chord tapers inward-aft towards the power takeoff hub rotation axis. 17. The method of claim 16 in which the angle between the power takeoff duct chord and the power takeoff hub rotation axis is between 1 and 5 degrees.
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이 특허에 인용된 특허 (16)
Haney William R. (6507 Foxboro Dr. Mayfield Village OH 44143), Air foil providing vortex attenuation.
Kroll William B. (Roscoe IL) Curran Patrick D. (Rockford IL), Deployable vortex turbine for dissipating or extracting energy from a lift induced vortex emanating from an aircraft.
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