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WO2003008267A1 - Extremite en boucle ovale pour pales de voilures tournantes - Google Patents

Extremite en boucle ovale pour pales de voilures tournantes Download PDF

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Publication number
WO2003008267A1
WO2003008267A1 PCT/US2001/022243 US0122243W WO03008267A1 WO 2003008267 A1 WO2003008267 A1 WO 2003008267A1 US 0122243 W US0122243 W US 0122243W WO 03008267 A1 WO03008267 A1 WO 03008267A1
Authority
WO
WIPO (PCT)
Prior art keywords
tip
rotary
rotor
wing
blade
Prior art date
Application number
PCT/US2001/022243
Other languages
English (en)
Inventor
T. Alan Egolf
Brian E. Wake
Original Assignee
United Technologies Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by United Technologies Corporation filed Critical United Technologies Corporation
Priority to PCT/US2001/022243 priority Critical patent/WO2003008267A1/fr
Publication of WO2003008267A1 publication Critical patent/WO2003008267A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C27/00—Rotorcraft; Rotors peculiar thereto
    • B64C27/32—Rotors
    • B64C27/46—Blades
    • B64C27/463—Blade tips
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C23/00—Influencing air flow over aircraft surfaces, not otherwise provided for
    • B64C23/06—Influencing air flow over aircraft surfaces, not otherwise provided for by generating vortices
    • B64C23/065—Influencing air flow over aircraft surfaces, not otherwise provided for by generating vortices at the wing tips
    • B64C23/069—Influencing air flow over aircraft surfaces, not otherwise provided for by generating vortices at the wing tips using one or more wing tip airfoil devices, e.g. winglets, splines, wing tip fences or raked wingtips
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T50/00—Aeronautics or air transport
    • Y02T50/10—Drag reduction

Definitions

  • This invention relates to wings, and more particularly to rotary-wing blade tips for aircraft. More particularly still, the invention relates to an improved rotary-wing blade tip for noise reduction.
  • a spiroidal tip device of particular geometry and orientation depicted in Prior Art Figs. 1A-1C, is used principally to reduce induced drag.
  • a typical wing end portion 1 has a spiroid 2 attached thereto.
  • the spiroid 2 joins the wing at a sweep angle ⁇ , measured relative to the wing tip chord line 4 and included angle ⁇ , measured relative to the projected wing plane 3.
  • the subscripts F and A are used to designate the forward and aft ends respectively.
  • the spiroid surface cross sections are typical airfoil sections 5, shown inset in Fig. 1A.
  • the spiroid chord which is a function of distance along a spiroidal generator 6, decreases approximately linearly from slightly more than half the wing tip chord at its forward end to about 0.3 of the wing tip chord at the spiroid midpoint; thereafter it increases approximately line-arly to about half the wing tip chord at its aft end.
  • Another undesirable effect of such tip vortices is the noise, typically audible, created when the vortex interacts with an object, such as another trailing blade or the body and empennage structures of an aircraft. This phenomenon is known as blade vortex interaction, or simply, "BVI".
  • the resulting noise may be particularly objectionable with respect to the operation of rotorcraft, such as helicopters, tilt-rotors, and other rotary-wing aircraft, especially during low speed descent to landing and maneuvers. It is this latter effect (i.e., BVI) that is to be addressed by the present invention.
  • ⁇ 068 Patent also suggests applicability of its spiroid-tipped wing to reduce noise and that it may be used with helicopters, its geometry and orientation are relatively complex and not well suited for use under the high centrifugal loadings imposed by rotary-wing aircraft.
  • the spiroid- tipped wing of that patent discloses only an arrangement that is highly asymmetrical to the loadings normally occasioned at the tip of a rotary-wing blade, as noted by the placement of spiroid 2 entirely above the extended plane 3 of wing 1.
  • its geometry is sufficiently varied over the extent of the spiroid as to make it difficult to manufacture.
  • the present invention is for an improved aircraft rotor having a plurality of rotary-wing blades for rotation in a direction about a common rotor axis.
  • Each of the rotary-wing blades includes a tip portion radially outward from the rotor axis, which tip portion is improved by the inclusion of an ovate loop tip at its radially outer end.
  • Each ovate loop tip has an ovate geometry transverse to the direction of blade rotation and is substantially symmetric with respect to a plane defined substantially by the chord of the tip portion of the rotary-wing blade.
  • the ovate loop tip structure reduces substantially the intensity of blade tip vortices, thereby also reducing the noise otherwise produced by blade vortex interference.
  • the loop forming the ovate loop tip comprises upper and lower halves that are substantially coextensive and coincident with each other in the direction of ro or rotation.
  • Each of the loop halves has a root portion, and the respective root portions of the upper and lower halves are attached to the rotary-wing tip portion.
  • the upper and lower halves of the ovate loop diverge at an angle ⁇ from their attachment at their respective roots with the rotary-wing tip portion, that angle ⁇ being less than 90°, typically in the range of 35° to 65°.
  • each ovate loop tip is substantially a linear continuum of the leading edge of the rotary-wing tip portion adjacent thereto, both of which may be rearwardly swept relative to the direction of rotor rotation.
  • the ovate loop tip has a geometry in the form of airfoil sections, with fore to aft thickness in the chordal direction. In the illustrated embodiment, the thickness is substantially constant over the entire upper and lower halves of the ovate loop tip, however variations may occur as required to satisfy the objects of the invention.
  • the ovate loop tip also is provided with twist, which may be constant or may vary around the loop commensurate with good design practice.
  • Figs. 1A, IB, and 1C are, respectively, a plan view, a rear view, and a left-hand side view of a spiroid- tipped wing in accordance with the Prior Art;
  • Fig. 2 is a diagrammatic plan view of an aircraft rotor having 4 rotary-wing blades, and showing blade vortex generation and interaction
  • Fig. 3A is a plan view of the tip portion of a rotary-wing blade with tip sweep, showing the ovate loop tip of the invention attached at the blade tip;
  • Fig. 3B is a front view, looking aft, of the rotary- wing blade with ovate loop tip of Fig. 3A;
  • Fig. 3C is an airfoil section of the ovate loop tip of Fig. 3B, taken along line 3C-3C thereof;
  • Fig. 4 is a perspective view of the rotary-wing ovate loop tip of the invention.
  • a wing end portion 1 with a spiroid 2 attached thereto as described previously with respect to the 068 patent in the Background Art section.
  • the wing-tip spiroid of that patent varies its chord length as a function of the length of the spiroid, as well as varying the twist of that airfoil.
  • the spiroid is asymmetrically positioned relative to the projected wing plane 3, with substantially the entire spiroid 2 being positioned above that plane.
  • FIG.2 there is depicted a plan- view diagram of the rotor 10 of a multi-blade, rotary- wing aircraft, as for instance, a helicopter.
  • the rotor 10 includes four rotary-wing blades 12 connected for counterclockwise rotation about the rotor axis 14.
  • the radially outward portions of blades 12 are termed the tip portions 16, and include the end tips of the blades 12 being illustrated as swept in this embodiment, though it is not essential to the invention. It is at the outer ends of these tip portions 16 that the disruptive vortices are formed.
  • These tip vortices are represented by the solid/broken lines 18 trailing from the tips of the respective blades 12.
  • FIG. 2 depicts the aircraft (not shown) and its rotor 10 moving from right to left, and the relative wind velocity vector V is depicted as being directed from left to right.
  • the reference for blade azimuth angle ⁇ is presumed to be the longitudinal centerline of the aircraft, extending aft from the rotor axis 14.
  • the lines 18 represent a kinematic prediction of the paths taken by the vortices shed by the rotor 10 at an advance ratio of 0.2.
  • the solid line portions 18' of vortices 18 represent the generation of those vortices at the tip portions 16 of the blades 12, both for advancing side blades and for retreating side blades.
  • the solid line portions 18 " of vortices 18 represent vortex interactions with subsequent advancing and retreating side blades, which then result in noise.
  • Fig. 3A depicts an ovate loop tip 20 affixed to the radially outer end of a blade 12 having a tip portion 16 of large swept tapered design.
  • the blade 12 is advancing from right to left, as in the 1 st or 2 nd quadrants of rotation of the rotor 10.
  • the ovate loop tip 20, or simply OLT 20 is formed as a continuous loop having upper and lower halves 20' and 20" respectively, seen in Fig.
  • the OLT 20 as viewed in the front view of Fig. 3B in the direction of relative blade to air motion, has an ovate cross-sectional shape. This shape has been found to significantly reduce the intensity of the vortex created at the tip region of the rotary-wing blades 12.
  • the OLT 20 of the present invention is substantially symmetrical with respect to a plane 24 which is defined substantially by "the locus of the chord of blade 12 in its tip portion 16, which plane is also nominally the plane of the blade in that region.
  • the upper and lower halves 20' and 20" of the OLT 20 diverge at an interior angle ⁇ from their attachment to the blade tip portion 16 at their common root chord 22. That angle ⁇ is less than 90°, typically being in the range of about
  • the radially outer portion of the OLT 20 comprises the arc of a circle having its center on the plane 24 and being of such diameter and length as to smoothly transition with the root-end portion at angle ⁇ .
  • the OLT 20 is substantially symmetrical about the chordal plane 24 of tip portion 16. 5 This geometry minimizes out-of plane loading and stresses on the blade 12, and effectively reduces the energy and intensity of any resulting tip vortex.
  • the fore to aft length of the chord of the OLT 20 is substantially constant for the entire spanwise extent of the OLT, that length being substantially the same as the length of its root chord 22.
  • this chord length parameter may vary along
  • At least the leading edge of the OLT 20 forms a substantially linear continuum with the leading edge of the tip portion 16 to which it is
  • the tip portion 12 is tapered but the OLT 20 has a constant chord length, it will be noted that the trailing edge of the OLT 20 may be at a different angle than the trailing edge of the tip portion 12, however this difference is minor and of no significant adverse consequence. In fact, the OLT 20 could be tapered.
  • Fig. 3c depicts an airfoil section of the OLT 20, and is a NACA 0007 airfoil section. Because the geometry of the exemplary embodiment of the invention is relatively constant for the entirety of the OLT 20, the depicted airfoil section is generally representative of an airfoil section anywhere along either of the upper and lower halves 20' and 20'' of the OLT. However, it will be appreciated that the range of good aerodynamic design practice does allow for variation in at least the chordal length of OLT 20 along its upper and lower halves 20' and 20' ' , in which case the airfoil section may vary accordingly.
  • the airfoil section may vary somewhat in shape and orientation as a function of its position on the OLT 20.
  • the resulting vortex shed from this tip region of the blade 12 is substantially more diffused and has a larger core diameter than would otherwise be the case without the OLT 20.

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  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)

Abstract

Le bruit d'interaction dû au tourbillon des pales (BVI), associé au fonctionnement d'un aéronef à voilure tournante est réduit grâce à l'inclusion d'un bout en boucle ovale (20) à la portion d'extrémité (16) de chacune des pales. L'extrémité en boucle (20) est de forme générale ovale, transversalement à la direction de rotation des pales (12) de la voilure tournante. L'extrémité en boucle ovale (20) comprend des moitiés supérieure et inférieure (20, 20') de géométrie analogue ou sensiblement identique, et est positionnée sensiblement symétriquement par rapport à un plan (24) défini sensiblement par la corde de profil de la pale de la voilure tournante, ou au voisinage de la portion d'extrémité (16). Les moitiés supérieure et inférieure (20', 20'') de l'extrémité en boucle ovale (20) ont une origine commune ou un pied de pale commun à leur point de liaison avec la portion d'extrémité (16) de la pale. Cette géométrie et ce positionnement de l'extrémité de boucle ovale (20) réduisent l'intensité du tourbillon d'extrémité résultant, tout en minimisant les charges et les contraintes additionnelles sur la pale.
PCT/US2001/022243 2001-07-16 2001-07-16 Extremite en boucle ovale pour pales de voilures tournantes WO2003008267A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US2001/022243 WO2003008267A1 (fr) 2001-07-16 2001-07-16 Extremite en boucle ovale pour pales de voilures tournantes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US2001/022243 WO2003008267A1 (fr) 2001-07-16 2001-07-16 Extremite en boucle ovale pour pales de voilures tournantes

Publications (1)

Publication Number Publication Date
WO2003008267A1 true WO2003008267A1 (fr) 2003-01-30

Family

ID=21742701

Family Applications (1)

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PCT/US2001/022243 WO2003008267A1 (fr) 2001-07-16 2001-07-16 Extremite en boucle ovale pour pales de voilures tournantes

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2223853A1 (fr) * 2009-02-25 2010-09-01 Deutsches Zentrum für Luft- und Raumfahrt e.V. Surface à écoulement dynamique dotée d'une turbine entraînée par un écoulement induit à l'aide de la surface d'écoulement
GB2524824A (en) * 2014-04-04 2015-10-07 Airbus Operations Ltd An aircraft wing with a wing tip device and a strut
GB2580064A (en) * 2018-12-20 2020-07-15 Airbus Operations Ltd Wingtip device for an aircraft
US11136109B2 (en) 2015-11-30 2021-10-05 General Electric Company Airfoil for a rotary machine including a propellor assembly

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR726674A (fr) * 1931-11-24 1932-06-01 Perfectionnements aux surfaces portantes des appareils se mouvant dans un fluide
US5102068A (en) 1991-02-25 1992-04-07 Gratzer Louis B Spiroid-tipped wing
DE19752369A1 (de) * 1997-11-26 1999-05-27 Rudolf Dr Bannasch Schlaufenförmiger Quertriebskörper (Splitwing Loop)

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR726674A (fr) * 1931-11-24 1932-06-01 Perfectionnements aux surfaces portantes des appareils se mouvant dans un fluide
US5102068A (en) 1991-02-25 1992-04-07 Gratzer Louis B Spiroid-tipped wing
DE19752369A1 (de) * 1997-11-26 1999-05-27 Rudolf Dr Bannasch Schlaufenförmiger Quertriebskörper (Splitwing Loop)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2223853A1 (fr) * 2009-02-25 2010-09-01 Deutsches Zentrum für Luft- und Raumfahrt e.V. Surface à écoulement dynamique dotée d'une turbine entraînée par un écoulement induit à l'aide de la surface d'écoulement
GB2524824A (en) * 2014-04-04 2015-10-07 Airbus Operations Ltd An aircraft wing with a wing tip device and a strut
US10501170B2 (en) 2014-04-04 2019-12-10 Airbus Operations Limited Aircraft wing with a wing tip device and a strut
GB2524824B (en) * 2014-04-04 2020-06-24 Airbus Operations Ltd An aircraft wing with a wing tip device and a strut
US11136109B2 (en) 2015-11-30 2021-10-05 General Electric Company Airfoil for a rotary machine including a propellor assembly
GB2580064A (en) * 2018-12-20 2020-07-15 Airbus Operations Ltd Wingtip device for an aircraft

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