WO2006027630A2 - Procede de regulation de l'eclatement de tourbillons - Google Patents

Procede de regulation de l'eclatement de tourbillons Download PDF

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Publication number
WO2006027630A2
WO2006027630A2 PCT/GB2005/050147 GB2005050147W WO2006027630A2 WO 2006027630 A2 WO2006027630 A2 WO 2006027630A2 GB 2005050147 W GB2005050147 W GB 2005050147W WO 2006027630 A2 WO2006027630 A2 WO 2006027630A2
Authority
WO
WIPO (PCT)
Prior art keywords
wing
gas
vanes
fins
leading edge
Prior art date
Application number
PCT/GB2005/050147
Other languages
English (en)
Other versions
WO2006027630A3 (fr
Inventor
Clyde Warsop
Norman Wood
Artur Jerzy Jaworski
Mark Watson
Original Assignee
Bae Systems Plc
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 Bae Systems Plc filed Critical Bae Systems Plc
Publication of WO2006027630A2 publication Critical patent/WO2006027630A2/fr
Publication of WO2006027630A3 publication Critical patent/WO2006027630A3/fr

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Classifications

    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C2230/00—Boundary layer controls
    • B64C2230/02—Boundary layer controls by using acoustic waves generated by transducers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C2230/00—Boundary layer controls
    • B64C2230/18—Boundary layer controls by using small jets that make the fluid flow oscillate
    • 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 a method of controlling vortex bursting on an aerodynamic surface associated with separated flows and, in particular, relates to control of flows over aerodynamic surfaces that may have highly-swept leading edges, including but not limited to delta wing surfaces.
  • Many high-performance aircraft and missiles employ lifting surfaces that have highly-swept leading edges, e.g. delta wings.
  • Such wings utilise a strong axial vortex over their upper surface to augment the lift force they can produce at various angles of attack.
  • the vortex is derived from flow separation at the leading edge of the wing that, at high sweep angles, forms a separated shear layer that rolls up to form a strong, steady lift-inducing vortex.
  • the conical vortex structure originates at the apex of the wing, grows along the leading edge of the wing and passes into the wake behind the wing.
  • Vortex burst When a certain angle of attack is exceeded, this organised vortex structure rapidly stagnates and collapses at a point above the wing resulting in a highly unsteady flow region over a portion of the wing lifting surface, generally towards its trailing edge. This phenomenon is usually referred to as vortex burst or vortex breakdown. Vortex breakdown leads to unsteady flow over the rest of the wing. As the angle of attack is increased, the location of vortex bursts moves forward towards the apex of the wing leading to a greater portion of the wing being exposed to unsteady flow. The unsteady flow may cause significant structural loading of the wing and other adjacent components (so- called “buffeting”) that will lead to premature fatigue problems and even catastrophic failure.
  • the piston 14 or diaphragm 18 is driven in the direction shown by the arrows in Figure 1 and Figure 2 thereby forcing a jet of air out into the air flow over the leading edge of the wing 10 thereby influencing flow separation and, as a consequence, the lift generated by the wing 10.
  • Two frequencies of operation of the synthetic jet devices are mentioned. The first is half the shedding frequency of vortices on the wing leading edge such that an increase in lift is achieved. The second is twice the shedding frequency such that a decrease in lift is achieved (this is useful in combination with using half the frequency so that turns may be achieved by increasing the lift on one wing while decreasing the lift on the other). Typical shedding frequencies are provided of 12Hz for a lifting surface travelling through water at 0.8ms-1 and of 30Hz for a military jet travelling at 600ms-1.
  • the present invention provides a method of controlling vortex bursting on an aerodynamic surface of a wing, the method comprising providing a plurality of gas jets on or in said surface, the gas jets being equally spaced along at least a length of the wing, at the leading edge thereof or adjacent the leading edge within a distance therefrom corresponding to the leading 5% to 10% per cent of the chord of the wing measured in the direction of airflow across or under the surface, operating control means associated with the gas jets at a repeated frequency to emit pulses of gas therefrom, the gas being pulsed under pressure at regular intervals through the jets from at least one gas source so that there is pressure is maintained at ambient pressure between gas pulses.
  • the present invention provides a gas pulsing system for an aerodynamic wing in which a plurality of gas jets is provided, the gas jets being evenly distributed along or adjacent a leading edge of the wing, the gas jets being connected to a source of gas under pressure by control means for regular and intermittent operation to permit pulses of the gas under pressure to be emitted at the gas jets while maintaining gas pressure not - A - less than atmospheric when gas pulses are not emitted.
  • Provision of the regular and intermittent pulses of gas can be by any suitable device but we have found that an electromagnetic arrangement, where the control means are provided by solenoid operated valves, responding to an electrical signal, can provide adequate control of the pulse frequency.
  • This signal may be sinusoidal, impulse, square or amplitude modulated to effect repeated operation of the gas source.
  • Piezo-electric valves and rotary valves, employing high-speed rotors that periodically open and close an orifice, may also be used.
  • a method according to the present invention may further comprise the step of providing a signal with a frequency at least as large as the dominant frequencies in the variation of pressures on the wing caused by vortex bursts.
  • These frequencies have been found to be effective in controlling vortex bursting. Moreover, they are in contrast to the lower frequencies employed by Blackwelder for the purposes of controlling lift from an aerodynamic surface. The difference in frequencies arises from the fact Blackwelder operates at frequencies linked to the shedding frequency of vortices on the wing leading edge, whereas the present invention operates at frequencies linked to pressure variation at the vortex burst site.
  • the method comprises the step of providing a signal with a frequency that is a harmonic or sub-harmonic of a dominant frequency in the variation of pressures on the wing caused by vortex bursts.
  • the method may further comprise the step of providing a signal with a frequency an order of magnitude larger than the dominant frequencies in the variation of pressures on the wing caused by vortex bursts.
  • a signal with a frequency in the range 800Hz to 1200Hz is employed.
  • the gas jets may, as stated above, be supplied from a single gas source or optionally, from a plurality of gas sources and a method according to the present invention may then further comprise the step of operating the gas sources in phase.
  • the gas sources may be operated out of phase such that, for example, the flow of gas ejected by each gas jet into the airflow passing over the surface reaches a common point or common line simultaneously.
  • a gas jet may comprise a cavity defined by an enclosing wall set into the leading edge of the surface with a moveable element provided by the associated valve, with the enclosing wall providing an orifice to allow flow of a gas into the cavity.
  • the moveable element can permit a bleed of gas into the cavity to ensure that reduced pressure does not result from the ambient fluid flow over the surface where the system is installed. This may be achieved by locating the moveable element close to the exit of the gas jet. Providing a relatively-small orifice relative to the cavity ensures that gas is ejected from the cavity as a stream of vortical, jet-like disturbances.
  • the orifice may be a rectangular slit.
  • the orifice has a circular cross-section and may optionally have a diameter of less than 1 cm, 1 mm being particularly preferred.
  • the gas jets are pitched at about 45 degrees to the surface and skewed at about 90 degrees to the freestream flow over the surface.
  • the attitude of the gas jets may be varied according to prevailing conditions.
  • the source of gas can be provided by individual gas supplies each associated with its respective jet or the source may be any convenient arrangement of one or more gas supplies, including one or more pumps for pumping ambient air or air from a source of compressed air, in the case of a wing of an aircraft, or may be air directed from the compressor or turbine of a jet engine ducted through the wing to the jets.
  • the present invention also resides in an aircraft wing comprising the aerodynamic surface described immediately above.
  • the wing may be delta shaped.
  • the present invention also resides in an aircraft comprising such an aircraft wing (delta shaped or otherwise).
  • the present invention further provides, in another aspect a method of controlling vortex bursting on an aerodynamic surface of a wing having a leading edge and a trailing edge, the method comprising providing a plurality of fins or vanes on the surface, the fins or vanes being at least substantially equally spaced on the surface at the leading edge thereof, or adjacent the leading edge within a distance therefrom corresponding to the leading 5% to 10% per cent of the chord of the wing measured in the direction of airflow across or under the surface, operating control means associated with the fins or vanes to move the fins or vanes between a position in which they are at least flush with the surface and a position in which they are proud of the surface, the fins or vanes being movable at a repeatable frequency to generate vortices in the direction of flow across the surface.
  • the fins or vanes may be unidirectional or may be rotatable in an oscillatory motion once raised from the profile of the surface.
  • Means is provided for moving the fins or vanes; such means may provide mechanical, electromechanical, electromagnetic or piezoelectric control of the fins or vanes.
  • a method of controlling vortex bursting on an aerodynamic surface or a hydrodynamic surface having a leading edge and a trailing edge comprising providing a plurality of fins or vanes on the surface, the fins or vanes being at least substantially equally spaced on the surface at the leading edge thereof, or adjacent the leading edge within a distance therefrom corresponding to the leading 5% to 10% per cent of the chord of the surface, operating control means associated with the fins or vanes to adjust the attitude thereof relative to freestream flow over the surface, the fins or vanes being movable at a repeatable frequency to generate vortices in the direction of flow across the surface.
  • the fins or vanes may be movable in unison or separately and may be moved in different directions.
  • the present invention further provides a system for controlling vortex burst on an aerodynamic or hydrodynamic surface, the system comprising a plurality of fins or vanes mounted at or adjacent a leading edge of the surface in evenly spaced relationship.
  • Figure 3 is a plan view of a delta wing showing the location of discrete gas jets as used in one embodiment of the present invention
  • Figure 3A is a diagrammatic representation of part of a delta wing showing the position of gas jets relative to the leading edge of the wing according to one embodiment of the invention
  • Figure 4 is a cross-sectional view taken along line IV-IV of Figure 3;
  • Figure 5 is a cross-sectional view of the leading edge of the wing of Figure 3, showing a gas jet for use in one embodiment of the present invention
  • Figure 6 is a cross-sectional view corresponds to Figure 7, but shows detail of the vortex rings formed in the jet of air expelled from the gas jet;
  • Figure 7 illustrates diagrammatically an arrangement which permits the gas jet to be rotated
  • Figure 8 illustrates a cross-section of Figure 7
  • Figure 9 illustrates diagrammatically an arrangement similar to that of Figure 7 but illustrating the provision of a rotatable slit through which gas can be expelled;
  • Figure 10 illustrates a cross-section of Figure 9
  • Figure 11 is a plan view of a part of a highly swept wing having a plurality of fins or vanes mounted thereon in accordance with a further embodiment of the present invention
  • Figure 12 is a side elevation partly in section illustrating one fin or vane mounted on a portion of a wing such as is shown in Figure 11 ;
  • Figure 13 is a side elevation partly in section of a variant of Figure
  • Figure 14 is a side elevation partly in section and similar to Figure
  • Figure 15 is a plan view of a part of a highly swept wing, similar to Figure 11 but showing the fins or vanes thereon rotated in accordance with a further embodiment of the present invention
  • Figures 16 and 17 are side and front elevations of a fin or vane according to a further embodiment of the present invention.
  • Figure 3 shows a delta wing 20 having a plurality of gas jets 22.
  • the wing 20 has a sharp sweep angle and has a sharp trailing edge 24 formed by a bevelled lower surface, as best seen in the cross-sectional view of Figure 4.
  • the absolute shape and size of the wing 20 is not critical to the invention and any details given herein are for the purposes of illustration only.
  • the plurality of gas jets 22 is located adjacent the curved leading edge 26 of each wing 20, with an equal number of gas jets 22 on each side of the apex 25 arranged in symmetric fashion.
  • the gas jets 22 may be provided on an upper or lower surface of the wing and are located in a region up-stream of the primary separation line which leads to roll up of the vortex, and are equally spaced along at least a length of the leading edge of the wing that corresponds to the leading 5% to 10% per cent of the chord of the wing, this is shown in Figure 3A.
  • gas jets 22A, 22B of a sequence extending along and adjacent the leading edge 26A are shown, these gas jets are located rearwardly of the leading edge.
  • the distance by which they are set back from the leading edge of the wing is dependent upon the location of the gas jet along the leading edge.
  • the gas jet is preferably set back by a distance approximately 5% to 10% of the length of the chord passing through that location, the length of that chord being determined by the distance between the leading edge at that location and the trailing edge of the wing, measured in the direction of airflow or airstream over the surface.
  • the gas jets may be set back by a constant distance from the leading edge 26A.
  • Each gas jet 22 can generate a time-varying disturbance in the thin shear-layer flowing over the wing 20.
  • the gas jets 22 each comprise a small cylindrical orifice 28 extending through the leading edge of the wing as can be seen in Figure 5.
  • an electromagnetically operable valve 32 At the rear of the orifice 28 is an electromagnetically operable valve 32 that is made to open and close under the control of electrical signals supplied thereto to allow gas under pressure to flow through the valve and the orifice 28 in the direction indicated by the arrow of Figure 5.
  • the orifice 28 has a diameter of 1 mm.
  • the valves 32 are operated by a central signal generator (not shown) that can provide sinusoidal signals of variable frequency and amplitude.
  • the shape and size of the wing 20 is not critical, as the gas jets 22 will find useful application in any number of wings.
  • the method described herein could be applied to unsteady separated flows on other shapes (e.g., bluff bodies) where vortex bursting is a problem.
  • examples include missile and aircraft forebodies and tailfins.
  • the shape of the orifice 28 can also be varied from the circular cross- section described above to any number of shapes such as small rectangular slits.
  • the embodiment described above has the orifices 28 oriented to be normal to the leading edge 26 of the wing 20.
  • Alternative arrangements include skewing and pitching the jets so that they are off-normal relative to the leading edge 26.
  • the size and number of gas jets 22 can also be varied, as can their mode of operation.
  • the gas jets 22 are advantageously set back from the leading edge 26 of the wing 20 and may be provided on the upper wing surface or the lower wing surface at a distance from the leading edge, when measured in the airstream direction, which is approximately 10% of the local chord distance, i.e.
  • valves 32 As measured in the direct line from the leading edge of the wing through the position of the gas jet.
  • other waveforms such as impulse, square or amplitude modulated may be used.
  • a phase offset could be introduced between adjacent valves 32 such that the disturbances they create reach the location of vortex, the valves may be operated out of bursting coincidentally.
  • the actuators 22 described above blow air out from and draw air into the cavity 30, provided that the air pressure in the cavity does not fall below ambient, they may be adapted to blow air out only.
  • each gas jet 22 is mounted in a rotatable mount 50 which is in the form of a plate 52 set into the surface of a wing a part of which is shown at 54 either at or, in the preferred embodiment of the invention, adjacent the leading edge of the wing.
  • the gas jet 22 is provided by the end portion of a duct 56 which is inclined to the surface of the wing and to which gas under pressure can be fed from a gas supply (not shown) via a control valve (also not shown).
  • the plate 52 can be rotated so that gas can be expressed from the gas jet with the jet set at an angle other than in the direction of airflow over the wing. This construction will permit vortex creation at the gas jet outlet to optimise the effect of the gas, as described above.
  • Rotation of the plate 52 can be effected by mounting the plate 52 on a rotatable shaft 58 which can be controlled by conventional means to rotate the plate either in unison with others of the array of gas jets or independently thereof.
  • the control means can be operated to rotate the gas jets in the same direction or in counter clockwise directions.
  • FIGs 9 and 10 is shown a variation of the embodiment illustrated in Figures 7 and 8.
  • the gas jet is replaced by a slit 60 provided in the plate 52, the plate again being rotatable on a hollow spindle 62 through which gas can be supplied under pressure to the slit 60.
  • the attitude of each slit can be varied relative to the airflow over the wing in the same manner as described with reference to Figures 7 and 8.
  • FIG. 11 to 17 there are shown therein embodiments of the invention in which the orifices permitting pulsed air to be emitted at the leading edge 106 of a wing are replaced by fins or vanes 100 which are mounted at or adjacent the leading edge of a wing 102 in spaced relationship which is dependent upon the angle of incidence of the wing, its maximum angle of attack and the angle that the leading edge subtends relative to the axis of the aircraft.
  • the fins or vanes are equally spaced along at least a length of the leading edge of the wing that corresponds to the leading 5% to 10% per cent of the local chord of the wing.
  • Each fin or vane 100 can be positioned such that it is aligned with the direction of airflow over the wing, as shown in Figure 11.
  • Each fin or vane can be rigidly mounted on the surface of the wing but it is preferred that it is adjustable.
  • Each fin or vane 100 can be mounted in a slot provided therefore above and to the rear of the leading edge 106 of the wing a portion of which is as shown in diagrammatic form in Figure 12.
  • the fin or vane 100 can then be moved between a position in which it is raised from the slot to be proud of the surface of the wing and a further position in which it is flush with the surface of the wing, as shown in both Figures 13 and 14.
  • the fin or vane 100 is pivotally mounted so that it can be lowered until its uppermost surface is flush with the surface of the wing.
  • the fin or vane is physically lowered below the surface of the wing.
  • each fin or vane 100 can be rotatable about an axis when it is clear of the wing surface, as illustrated in Figure 15. If the fin or vane is mounted so that it is positioned on the wing surface, then it can be rotated in either direction about a fixed pivot. Alternatively, where the fin or vane is mounted to be retractable, it can be mounted on a retractable pivot so that it can be rotated when it is proud of the surface of the wing.
  • the fins of vanes can be rotated in unison or separately so that, for example, adjacent fins or vanes can be counter rotated.
  • each individual fin or vane may include one or more gas jets 104 providing one or more gas jets through which gas can be pulsed, thereby providing the dual advantage of having the fins or vanes providing the vortex formation previously described, enhanced by that produced by the presence of the pulses of gas.
  • the gas jets are coupled to conduits 108 provided in the body of the fin or vane which are connected via a control valve to a supply (not shown) of gas under pressure.

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  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Control Of Positive-Displacement Air Blowers (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
  • Aerodynamic Tests, Hydrodynamic Tests, Wind Tunnels, And Water Tanks (AREA)

Abstract

La présente invention concerne l'éclatement de tourbillons sur des structures de deltaplanes par répartition de jets de gaz et / ou d'ailettes / aubes le long du bord d'attaque ou en retrait de ce dernier pour émettre des impulsions de gaz à partir des jets de gaz dans le flux d'air s'écoulant sur le bord d'attaque des ailes.
PCT/GB2005/050147 2004-09-10 2005-09-08 Procede de regulation de l'eclatement de tourbillons WO2006027630A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB0420293.3A GB0420293D0 (en) 2004-09-10 2004-09-10 Method of controlling vortex bursting
GB0420293.3 2004-09-10

Publications (2)

Publication Number Publication Date
WO2006027630A2 true WO2006027630A2 (fr) 2006-03-16
WO2006027630A3 WO2006027630A3 (fr) 2006-06-08

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2005/050147 WO2006027630A2 (fr) 2004-09-10 2005-09-08 Procede de regulation de l'eclatement de tourbillons

Country Status (2)

Country Link
GB (1) GB0420293D0 (fr)
WO (1) WO2006027630A2 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7942994B2 (en) 2006-05-27 2011-05-17 Bae Systems Plc Bonding tool and method
CN103963964A (zh) * 2013-02-01 2014-08-06 株式会社东芝 漩涡产生装置及漩涡产生方法
US20220411046A1 (en) * 2019-11-21 2022-12-29 University Of Washington Vortex control on engine nacelle strake and other vortex generators

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4697769A (en) 1984-04-23 1987-10-06 Flow Industries, Inc. Method and apparatus for controlling bound vortices in the vicinity of lifting surfaces
GB2303135A (en) 1995-07-12 1997-02-12 Shell Int Research Process for incorporation of epoxidised polydienes into epoxy resins
WO2004110863A1 (fr) 2003-06-11 2004-12-23 Bae Systems Plc Procede de controle de la dislocation de tourbillons

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5758823A (en) * 1995-06-12 1998-06-02 Georgia Tech Research Corporation Synthetic jet actuator and applications thereof
US6457654B1 (en) * 1995-06-12 2002-10-01 Georgia Tech Research Corporation Micromachined synthetic jet actuators and applications thereof
US6390116B1 (en) * 2001-07-16 2002-05-21 Illinois Institute Of Technology Large amplitude pneumatic oscillator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4697769A (en) 1984-04-23 1987-10-06 Flow Industries, Inc. Method and apparatus for controlling bound vortices in the vicinity of lifting surfaces
GB2303135A (en) 1995-07-12 1997-02-12 Shell Int Research Process for incorporation of epoxidised polydienes into epoxy resins
WO2004110863A1 (fr) 2003-06-11 2004-12-23 Bae Systems Plc Procede de controle de la dislocation de tourbillons

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7942994B2 (en) 2006-05-27 2011-05-17 Bae Systems Plc Bonding tool and method
CN103963964A (zh) * 2013-02-01 2014-08-06 株式会社东芝 漩涡产生装置及漩涡产生方法
EP2769912A1 (fr) * 2013-02-01 2014-08-27 Kabushiki Kaisha Toshiba Appareil et procédé de génération de vortex
US10086926B2 (en) 2013-02-01 2018-10-02 Kabushiki Kaisha Toshiba Vortex generating apparatus and vortex generating method
US20220411046A1 (en) * 2019-11-21 2022-12-29 University Of Washington Vortex control on engine nacelle strake and other vortex generators

Also Published As

Publication number Publication date
GB0420293D0 (en) 2005-08-10
WO2006027630A3 (fr) 2006-06-08

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