High efficiency tip vortex reversal and induced drag reduction
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
B64C-023/06
B64C-023/00
B64C-003/00
출원번호
US-0483935
(2006-07-10)
등록번호
US-7497403
(2009-03-03)
발명자
/ 주소
McCarthy,Peter T.
출원인 / 주소
McCarthy,Peter T.
인용정보
피인용 횟수 :
4인용 특허 :
24
초록▼
Methods for increasing the performance of a foil (100) by using tip droop (102) having an inward directed camber capable of generating an inward directed lifting force on the tip droop (102) in order to control spanwise flow conditions adjacent the tip (112) of a foil (100). Methods for varying the
Methods for increasing the performance of a foil (100) by using tip droop (102) having an inward directed camber capable of generating an inward directed lifting force on the tip droop (102) in order to control spanwise flow conditions adjacent the tip (112) of a foil (100). Methods for varying the inward lifting shape of a tip droop (102) are provided along with methods for varying the angle of attack and camber of the tip droop (102) as the angle of attack of the foil (100) is changed and as spanwise flow conditions vary.
대표청구항▼
I claim: 1. A method for providing a foil, comprising: (a) providing a foil having an inward portion, a tip, a chordwise direction, a relatively higher pressure foil surface, a relatively lower pressure foil surface, a leading edge and a trailing edge, said foil having relative movement to a fluid
I claim: 1. A method for providing a foil, comprising: (a) providing a foil having an inward portion, a tip, a chordwise direction, a relatively higher pressure foil surface, a relatively lower pressure foil surface, a leading edge and a trailing edge, said foil having relative movement to a fluid medium that is arranged to permit said foil to experience lift generation that produces a foil lifting force on said foil having a direction that is substantially from said relatively higher pressure surface toward said relatively lower pressure surface, said tip having a tendency to create an induced drag vortex within said fluid medium in the wake behind said foil; and (b) providing a vortex generator connected to said foil near said tip, said vortex generator having a substantially streamwise alignment, said vortex generator being arranged to generate a counter vortex within said fluid medium in said wake behind said vortex generator that has a direction of spin that is opposite of said induced drag vortex, said vortex generator having a relatively lower pressure generator surface and a relatively higher pressure generator surface that are arranged to create a predetermined generator lifting force on said vortex generator, said vortex generator being oriented to substantially avoid creating a significant reduction in said foil lifting force on said foil during said lift generation, said substantially streamwise alignment being at an angle to said chordwise direction to generate said counter vortex; (c) adjusting said substantially streamwise alignment to control the strength of said counter vortex so as to create a reduction in the strength of said induced drag vortex. 2. The method of claim 1 wherein said vortex generator is arranged to generate said counter vortex in a manner effective to create a net increase in the efficiency of said lift generation of said foil. 3. The method of claim 1 wherein said predetermined generator lifting force is arranged to be oriented in a predetermined direction relative to said direction of said foil lifting force that is capable of minimizing the formation of a negative lifting force on said vortex generator that could significantly oppose said foil lifting force as said vortex generator generates said counter vortex, said predetermined direction being capable of increasing the efficiency of said lift generation of said foil. 4. The method of claim 3 wherein said predetermined direction of said predetermined generator lifting force is arranged to be substantially perpendicular to said direction of said foil lifting force. 5. The method of claim 1 wherein at least one portion of said vortex generator is arranged to generate a forward directed component of said predetermined generator lifting force. 6. The method of claim 1 wherein at least one portion of said vortex generator is arranged to create beneficial lifting force that is oriented in said direction of said foil lifting force during said lift generation of said foil. 7. The method of claim 1 wherein said vortex generator has a predetermined profile relative to said relative movement within said fluid medium, and the combination of said predetermined profile, said predetermined generator lifting force and said counter vortex are arranged to create an overall net increase in the efficiency of said foil during said lift generation. 8. The method of claim 1 further including providing said vortex generator with a predetermined profile relative said fluid medium that creates a predetermined generator profile drag on said foil during said relative movement, and selecting said predetermined profile of said vortex generator so as to permit said counter vortex to create an increase in the efficiency of said foil that exceeds said profile drag so as to create a net increase in said efficiency of said lift generation of said foil. 9. The method of claim 1 wherein said tip of said foil has a tendency to create an outward directed cross flow condition within said fluid medium relative to said relatively higher pressure foil surface near said tip, and said vortex generator is arranged to generate said counter vortex in manner effective to permit the rotation of said fluid medium within said counter vortex to create a net reduction in said outward cross flow condition relative to said tip. 10. The method of claim 9 wherein said net reduction in said outward spanwise expansion of said relatively higher pressure is sufficient to create an increase in the efficiency of said lift generation of said foil. 11. The method of claim 1 wherein said vortex generator is arranged to generate said counter vortex in a manner sufficient to create an upwash field within said fluid medium in said wake behind at least one portion of said foil, said upwash field is arranged to occur substantially in the direction of said foil lifting force during said lift generation of said foil. 12. The method of claim 1 wherein said counter vortex is arranged to form sufficiently close to said induced drag vortex in said wake to cause a reduction in the strength of said induced drag vortex. 13. The method of claim 1 wherein a downwash field is created by said induced drag vortex in said wake behind said foil, said downwash field extending in a substantially opposite direction to said direction of said lift generation, said vortex generator is arranged to generate said counter vortex with sufficient strength to create a net reduction in said downwash field. 14. The method of claim 1 wherein said vortex generator is arranged to generate said counter vortex in an amount sufficient to enable said counter vortex to move said induced drag tip vortex to a position within said wake that is inward of vortex generator. 15. The method of claim 1 wherein said vortex generator comprises an anhedral tip droop that extends downward below said relatively higher pressure foil surface. 16. The method of claim 15 wherein said relatively lower pressure generator surface is an inward surface on said anhedral tip droop, at least one portion of said inward surface being oriented at a divergent alignment relative to said relative movement of said fluid medium, said vortex generator being arranged to generate said counter vortex in a manner sufficient to create a net inward deflection within said fluid medium relative to said relatively higher pressure foil surface, and said net inward deflection being arranged to create an increase the efficiency of said lift generation. 17. The method of claim 15 wherein said relatively lower pressure generator surface comprises an inward surface relative to said foil and said relatively higher pressure generator surface comprises an outward surface relative to said foil, said inward surface being convexly curved along a chordwise direction and said outward surface being relatively straighter than said inward facing surface along said chordwise direction. 18. The method of claim 15 wherein said relatively lower pressure generator surface comprises an inward surface relative to said foil and said relatively higher pressure generator surface comprises an outward surface relative to said foil, said inward surface being arranged to be convexly curved along a chordwise direction and at least one portion of said outward surface being arranged to be concavely curved along said chordwise direction. 19. The method of claim 15 wherein said anhedral tip droop is curved in an outward and downward direction relative to said tip of said foil. 20. The method of claim 1 wherein said vortex generator is arranged to be pivotable. 21. The method of claim 1 wherein at least one movable flap member is connected to said vortex generator. 22. The method of claim 1 wherein at least one portion of said vortex generator is arranged to pivot around an axis that is substantially parallel to the direction of said foil lifting force of said foil. 23. A method for providing a foil, comprising: (a) providing a foil having an inward portion, a tip, a relatively higher pressure foil surface, a relatively lower pressure foil surface, a leading edge and a trailing edge, said foil having relative movement to a fluid medium that is arranged to permit said foil to experience lift generation that produces a foil lifting force on said foil having a direction that is substantially directed from said relatively higher pressure surface toward said relatively lower pressure surface; (b) providing an anhedral tip droop connected to said tip, said tip droop extending below said relatively higher pressure foil surface in a substantially vertical direction that is significantly perpendicular to the spanwise alignment of said foil, said tip droop having a lower end, a tip droop leading edge, a tip droop trailing edge, an inward surface and an outward surface; and (c) arranging said tip droop to be able to pivot around a substantially vertical axis relative to the plane of said foil, at least one pivoting portion of said tip droop being arranged to pivot to an outward position that is outward of said tip of said foil to form a gap between said at least one pivoting portion and said tip of said foil, said tip droop having a movable foil portion that is substantially parallel to the plane of said foil and is arranged to substantially fill said gap between said at least one movable foil portion of said tip droop and said tip of said foil when said tip droop is pivoted toward said outward position. 24. The method of claim 23 wherein said tip of said foil has a tendency to create an induced drag vortex within said fluid medium in the wake behind said foil during said lift generation, said anhedral tip droop having at least one counter vortex generating member that is arranged to generate a counter vortex within said fluid medium in said wake behind said foil that has a direction of spin that is opposite to said induced drag vortex. 25. The method of claim 24 wherein said at least one counter vortex generating member is arranged to generate said counter vortex in a manner effective to create a net increase in the efficiency of said lift generation of said foil. 26. The method of claim 24 wherein said at least one counter vortex generating member creates a predetermined generator lifting force that is arranged to be oriented in a predetermined direction relative to said direction of said foil lifting force that is capable of minimizing the formation of a negative lifting force on said vortex generator that could significantly oppose said foil lifting force as said at least one counter vortex generating member generates said counter vortex. 27. The method of claim 26 wherein said predetermined direction of said predetermined generator lifting force is arranged to be substantially perpendicular to said direction of said foil lifting force. 28. The method of claim 26 wherein at least one portion of said at least one counter vortex generating member is arranged to generate a forward directed component of said predetermined generator lifting force. 29. The method of claim 26 wherein said at least one counter vortex generating member has a predetermined profile relative to said relative movement within said fluid medium, and the combination of said predetermined profile, said predetermined generator lifting force and said counter vortex are arranged to create an overall net increase in the efficiency of said foil during said lift generation. 30. The method of claim 26 wherein said tip of said foil has a tendency to create an outward spanwise directed cross flow condition within said fluid medium relative to said relatively higher pressure foil surface near said tip, and said vortex generator is arranged to generate said counter vortex in manner effective to permit the rotation of said fluid medium within said counter vortex to create a net reduction in said outward cross flow condition relative to said tip. 31. The method of claim 30 wherein said net reduction in said outward cross flow condition of said relatively higher pressure is sufficient to create an increase in the efficiency of said foil. 32. The method of claim 26 wherein said at least one counter vortex generating member is arranged to generate said counter vortex in a manner sufficient to create an upwash field within said fluid medium in said wake behind at least one portion of said foil, said upwash field is arranged to occur substantially in the direction of said foil lifting force during said lift generation of said foil. 33. The method of claim 26 wherein said counter vortex is arranged to form sufficiently close to said induced drag vortex in said wake to cause a reduction in the strength of said induced drag vortex. 34. The method of claim 26 wherein a downwash field is created by said induced drag vortex in said wake behind said foil, said downwash field extending in a substantially opposite direction to said direction of said lift generation, said at least one counter vortex generating member is arranged to generate said counter vortex with sufficient strength to create a net reduction in said downwash field. 35. The method of claim 26 wherein said at least one counter vortex generating member is arranged to generate said counter vortex in an amount sufficient to enable said counter vortex to move said induced drag tip vortex to a position within said wake that is inward of vortex generator. 36. The method of claim 26 wherein said predetermined direction is arranged to increase the efficiency of said foil. 37. The method of claim 26 wherein at least one portion of said inward surface being oriented at a divergent alignment relative to said relative movement of said fluid medium, said at least one counter vortex generating member being arranged to generate said counter vortex in a manner sufficient to create a net inward deflection within said fluid medium relative to said relatively higher pressure foil surface, and said net inward deflection being arranged to create an increase the efficiency of said lift generation. 38. The method of claim 24 wherein a trailing portion of said tip droop is arranged to pivot. 39. The method of claim 24 wherein at least one portion of said at least one counter vortex generating member is arranged to create a beneficial lifting force that is oriented substantially in said direction of said foil lifting force during said lift generation of said foil. 40. The method of claim 24 further including providing said at least one counter vortex generating member with a predetermined profile relative said fluid medium that creates a predetermined generator profile drag on said foil during said relative movement, and selecting said predetermined profile of said at least one counter vortex generating member so as to permit said counter vortex to create an increase in the efficiency of said foil that exceeds said profile drag so as to create a net increase in said efficiency of said lift generation of said foil. 41. The method of claim 23 wherein said inward surface is convexly curved along a chordwise direction and said outward surface is less curved in said chordwise direction than said inward facing surface along said chordwise direction. 42. The method of claim 41 wherein said anhedral tip droop is curved in an outward and downward direction relative to said tip of said foil. 43. A method for providing a foil, comprising: (a) providing a foil having an inward portion, a tip, an upper surface, a lower surface, a foil leading edge and a foil trailing edge, said foil having a plane of said foil that extends between said foil leading edge and said foil trailing edge, said foil having relative movement to a fluid medium that is arranged to permit said foil to experience lift generation that produces a foil lifting force on said foil having a lift direction that is substantially directed from said relatively lower surface toward said upper surface, said foil having a tendency to create an induced drag vortex within said fluid medium in the wake behind said foil trailing edge that creates a drag inducing downwash field within said fluid medium in said wake behind said foil trailing edge that increases the net total drag created on said foil during said lift generation; (b) providing a winglet connected to said foil near said tip that extends in a substantially vertical direction away from the said plane of said foil, said vertical winglet having a root portion, an outward surface, an inward surface, an outer end, a winglet leading edge, a winglet trailing edge, and a midpoint of said winglet that is midway between said winglet leading edge and said winglet trailing edge; and (c) arranging said winglet to experience pivotal movement around a substantially vertical axis relative to the plane of said foil to a predetermined angle of attack relative to the chordwise direction of said foil near said tip and, said substantially vertical axis being sufficiently spaced from said midpoint of said winglet to permit said midpoint of said winglet to experience significant spanwise movement relative to said foil during said pivotal movement, wherein both said winglet and said predetermined angle of attack create a net counter vortex pattern that rotates in the opposite direction of said induced drag vortex in said wake behind said foil trailing edge, said net counter vortex pattern is arranged to be sufficiently strong enough relative to the strength of said induced drag vortex to create a net reduction in said net total drag on said foil when said winglet has pivoted to said predetermined angle of attack relative to said chordwise direction of said foil. 44. The method of claim 43 wherein said substantially vertical axis is located sufficiently closer to said winglet leading edge than said winglet trailing edge to cause said winglet trailing edge to experience a greater amount of said spanwise movement relative to said foil than said winglet leading edge during said pivotal movement. 45. The method of claim 43 wherein said substantially vertical axis is located sufficiently closer to said winglet trailing edge than said winglet leading edge to cause said winglet leading edge to experience a greater amount of said spanwise movement relative to said foil than said winglet trailing edge during said pivotal movement. 46. The method of claim 43 wherein said upper and lower surfaces being opposing surfaces, said winglet being a substantially independent pivoting winglet and said substantially independent pivoting winglet being arranged to extend vertically away from only one of said opposing surfaces but not the other of said opposing surfaces in an amount effective to permit said substantially independent pivoting winglet to substantially generate only said net counter vortex pattern that rotates in said opposite direction of said induced drag vortex of said foil while simultaneously avoiding creating a significantly strong drag inducing vortex that spins in the same direction of said induced drag vortex. 47. The method of claim 43 wherein said winglet has a predetermined range of pivotal movement relative to said foil, and a movable foil portion that is substantially parallel to said plane of said foil is connected to said winglet and is arranged to substantially prevent the formation of a spanwise gap between said winglet and said tip of said foil when said tip droop is pivoted across said predetermined range of pivotal motion. 48. A method for providing a foil, comprising: (a) providing a foil having an inward portion, a tip, opposing surfaces including a relatively higher pressure foil surface; and a relatively lower pressure foil surface, a leading edge, a trailing edge, and a plane extending between said leading and trailing edges, said foil having relative movement to a fluid medium that is arranged to permit said foil to experience lift generation that produces a foil lifting force on said foil having a direction that is substantially from said relatively higher pressure surface toward said relatively lower pressure surface, said tip having a tendency to create an induced drag vortex within said fluid medium in the wake behind said foil; (b) providing a vortex generator connected to said foil near said tip, said vortex generator having a substantially streamwise alignment, said vortex generator having at least one relatively stationary foil shaped portion that remains relatively stationary during use and said vortex generator having at least one movable foil shaped portion that is arranged to experience a predetermined range of pivotal motion around a predetermined axis that is substantially perpendicular to said relatively higher pressure foil surface, said at least one movable foil shaped portion extending significantly away from only one of said opposing surfaces to a significant vertical distance from said one of said opposing surfaces, said at least one predetermined region of said vortex generator being arranged to generate a counter vortex within said fluid medium in said wake behind said vortex generator that has a direction of spin that is opposite of said induced drag vortex, and providing a movable foil portion that is substantially parallel to said plane of said foil and is arranged to substantially prevent the formation of a spanwise gap between said winglet and said tip of said foil when said tip droop is pivoted across said predetermined range of pivotal motion; and (c) arranging said at least one predetermined region of said vortex generator to generate said counter vortex with sufficient strength to create a net reduction in the strength of said induced drag vortex. 49. A method for providing a foil, comprising: (a) providing a foil having an inward portion, a tip, opposing surfaces that include a relatively higher pressure foil surface; and a relatively lower pressure foil surface, a leading edge and a trailing edge, said foil having relative movement to a fluid medium that is arranged to permit said foil to experience lift generation that produces a foil lifting force on said foil having a direction that is substantially from said relatively higher pressure surface toward said relatively lower pressure surface, said tip having a tendency to create an induced drag vortex within said fluid medium in the wake behind said foil; and (b) providing a vortex generator connected to said foil near said tip, said vortex generator having a substantially streamwise alignment, said vortex generator being arranged to generate a counter vortex within said fluid medium in said wake behind said vortex generator that has a direction of spin that is opposite of said induced drag vortex, said vortex generator having a relatively lower pressure generator surface and a relatively higher pressure generator surface that are arranged to create a predetermined generator lifting force on said vortex generator, said vortex generator being oriented to substantially avoid creating a significant reduction in said foil lifting force on said foil during said lift generation, said vortex generator having at least one independently pivoting vortex generator member that extends significantly away from only one of said opposing surfaces and is arranged to experience pivotal motion around a substantially vertical axis relative said one of said opposing surfaces so as to not create a significant winglet induced drag vortex that spins in the same direction of said induced drag vortex of said foil while generating said counter vortex. 50. The method of claim 49 wherein said at least one independently pivoting vortex generator member having a vortex generator leading edge, a vortex generator trailing edge, and a longitudinal midpoint between said vortex generator leading edge and said vortex generator trailing edge, said vertical axis being disposed in an area between said vortex generator leading edge and said longitudinal midpoint. 51. The method of claim 50 wherein said at least one independently pivoting vortex generator member has a predetermined range of pivotal movement relative to said foil, and a movable foil portion that is substantially parallel to said plane of said foil is connected to said at least one independently pivoting vortex generator member and is arranged to substantially prevent the formation of a spanwise gap between said winglet and said tip of said foil when said tip droop is pivoted across said predetermined range of pivotal motion.
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