Dome for aircraft flap mechanism

Abstract

The invention relates to a fairing (26) for a flight vehicle flap mechanism, comprising a fairing front section (32) located in front of the trailing edge of the flight vehicle wing and a fairing rear section (33) located behind the trailing edge of the flight vehicle wing, the fairing front section (32) and the fairing rear section (33) meeting in a bottom region of the fairing (26) at a front-rear section meeting point (P3), the lowest point (P2) of the fairing rear section (33) being at a height which is lower than or equal to the height of the front-rear section meeting point (P3). Compared to conventional fairing solutions, the use of a fairing according to the invention not only leads to a significant reduction in lift loss, but also to an improved wing circulation distribution in flight, both resulting in an increase in aerodynamic efficiency.

Description

Technical Field

[0001] This invention relates to a fairing structure, and more specifically, to an improved fairing structure for an aircraft flap mechanism. Background Technology

[0002] To ensure safe flight of aircraft under varying speeds and attitudes, those skilled in the art typically employ various movable surface measures based on the wing shape during cruise to increase lift. These lift-enhancing devices are called lift-boosting devices. Lift-boosting devices are generally used during takeoff and landing and usually fall under the category of low-speed aerodynamics.

[0003] Modern large civil aircraft typically employ lift enhancement systems such as leading-edge slats, Kruger flaps, leading-edge droop flaps, and trailing-edge flaps. Because of the relative motion between the lift enhancement system and the main wing, additional mechanisms are required to achieve these motions. For example, the trailing-edge flap mechanism protrudes from the original clean wing, necessitating the installation of an additional fairing for the flap mechanism. Conventional fairings reduce local lift, alter the aircraft's wingspan loading, and increase drag on the wing, resulting in numerous adverse effects.

[0004] Chinese invention patent application CN111284683A, filed by Bombardier on December 10, 2019, entitled "Aircraft Wing Assembly," discloses an aircraft and an aircraft wing assembly for the aircraft. The wing assembly includes a wing body assembly comprising a wing body and at least one protruding portion connected to the wing body. The protruding portion extends rearward from the rear side of the wing body assembly. The leading edge of the wing body assembly defines a leading edge line, and the trailing edge of the wing body assembly defines a trailing edge line extending between an inner end and an outer end, the trailing edge including the trailing edge of the protruding portion. The trailing edge line is a smooth line, and a chord distance is defined longitudinally from the leading edge line to the trailing edge line. The chord distance at the center of the protruding portion is greater than the chord distances at the inner and outer sides of the protruding portion.

[0005] The aforementioned technical solution addresses the adverse effects of the flap fairing by increasing the local chord length of the wing to mitigate lift reduction. However, this solution has drawbacks: it significantly alters the wing's projected area and adds additional structural weight.

[0006] A method for adjusting the lift distribution of an aircraft wing is disclosed in PCT international invention patent application CN101678892A, filed by Boeing on May 16, 2008, entitled "Aerospace Vehicle Fairing System and Auxiliary Method Thereof". The method includes: positioning the point of maximum curvature of a first fairing at least approximately forward of the trailing edge of the wing near a first inboard portion of the wing, based at least partially on a target lift distribution; and positioning the point of maximum curvature of a second fairing at least approximately behind the trailing edge of the wing near a second outboard portion of the wing, based at least partially on the target lift distribution.

[0007] The aforementioned technical solution proposes altering the relative position of the maximum curvature location point to the wing trailing edge to improve lift distribution. However, given a fixed flap mechanism, the maximum curvature location point is constrained by the available space. If the maximum curvature point is located behind the wing trailing edge, it would increase the fairing's volume, adding extra weight and increasing overall aircraft drag.

[0008] Therefore, it is necessary to design a fairing for the flap mechanism that can solve the above-mentioned shortcomings. This fairing can optimize the wingspan load of the aircraft and reduce the lift loss of the fairing through simple design. Summary of the Invention

[0009] The purpose of this invention is to provide a fairing for a flap mechanism that, through a simple design, can optimize the wingspan load of an aircraft and reduce lift loss.

[0010] A first aspect of the present invention relates to a fairing for an aircraft flap mechanism, comprising:

[0011] The forward section of the fairing located in front of the trailing edge of the aircraft's wing; and

[0012] The rear section of the fairing, located behind the trailing edge of the aircraft's wing.

[0013] The front and rear sections of the fairing meet at the junction point between the front and rear sections in the bottom region of the fairing.

[0014] The lowest point of the rear section of the fairing is lower than or equal to the height of the junction between the front and rear sections.

[0015] In the above technical solutions, the terms "front," "rear," "top," "bottom," and "lowest point" all refer to an aircraft in normal flight. In special cases, these terms will change as the state of the reference object changes.

[0016] The front and rear sections of the fairing are defined by their horizontal height based on the streamlined shape of the fairing, regardless of whether they are independent of each other or form a single unit. Those skilled in the art can divide the fairing into two parts based on common knowledge in the field, and the term "boundary" in the technical description encompasses the meaning of convergence and joining, which is readily understood by those skilled in the art.

[0017] The “top region” and “bottom region” of the fairing refer to the surface regions of the fairing located at the top and bottom of the aircraft relative to it, the exact locations of which are well known to those skilled in the art.

[0018] In a preferred embodiment, the fairing can extend rearward along a straight line from the junction of the front and rear sections in the direction of the local airfoil chord, in which case the lowest point of the rear section of the fairing is not higher than this straight line.

[0019] Preferably, the rear section of the fairing can be monotonically bent downwards, in which case the lowest point of the rear section of the fairing is the lower trailing edge point of the rear section in the bottom region of the fairing.

[0020] In the above embodiment, if the height difference between the lower trailing edge point of the rear segment and the junction point of the front and rear segments is h1, and the lower trailing edge point of the rear segment being located above the straight line is defined as a positive value, then h1≤0.

[0021] Ideally, the absolute value of the height difference h1 can be less than or equal to 5% of the local airfoil chord length.

[0022] In the above embodiments, the term "monotonous" refers to the fact that, taking any two points along the entire length of the rear section of the fairing, the absolute value of the distance between these two points and the aforementioned straight line (or, the height difference between these two points and the junction of the front and rear sections) always gradually increases along the direction from the nose to the tail of the aircraft.

[0023] In another preferred embodiment, the rear section of the fairing may intersect with the plane of the local airfoil. In this case, the first intersection line obtained in the top region of the fairing is a straight line or an outwardly convex curve, and is tangent to the main wing of the aircraft at the main wing junction.

[0024] Preferably, if the first intersection line is a straight line, an arc-shaped surface can be used near the intersection of the main wings to ensure a smooth transition of curvature.

[0025] In the above embodiments, the rear section of the fairing may intersect with the plane where the local airfoil is located. In this case, the second intersection line obtained in the bottom region of the fairing is a straight line or a concave curve, and is tangent to the front section of the fairing at the junction of the front and rear sections.

[0026] Preferably, if the second intersection line is a straight line, an arc-shaped surface can be used near the intersection point of the front and rear segments to ensure a smooth transition of curvature.

[0027] A second aspect of the invention relates to an aircraft equipped with a flap mechanism and a fairing as described above, wherein the fairing is used for the flap mechanism of the aircraft.

[0028] The fairing for the flap mechanism according to the present invention offers the following advantages:

[0029] (1) The present invention utilizes the change in the shape of the fairing along the flow direction to improve the local pressure distribution and optimize the wingspan load of the aircraft;

[0030] (2) Compared with conventional fairing schemes, not only is the lift loss significantly reduced, but the wing circulation distribution in flight is also improved, both of which lead to improved aerodynamic efficiency. Attached Figure Description

[0031] To further illustrate the technical effects of the fairing used in the flap mechanism according to the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, wherein:

[0032] Figure 1 This is a schematic diagram of an aircraft with a fairing for a flap mechanism installed;

[0033] Figure 2 It is a wing along the fairing equipped with a conventional flap mechanism. Figure 1 The sectional view obtained after cutting along line AA in the diagram;

[0034] Figure 3 yes Figure 2 A schematic diagram of lift loss of the fairing shown;

[0035] Figure 4 The wing edge is equipped with a fairing for the flap mechanism according to the present invention. Figure 1 The sectional view obtained after cutting along line AA in the diagram;

[0036] Figure 5 yes Figure 4 A schematic diagram illustrating the lift gain of the fairing;

[0037] Figure 6 The coordinate axes are shown with the horizontal axis representing wingspan and the vertical axis representing wingspan load, where the change in wing load gain is shown by comparing the wing load curves of the fairing according to the invention and a conventional fairing.

[0038] Figure Labels

[0039] 21. Nose

[0040] 22 fuselage

[0041] 23 Wings

[0042] 24 posterior body

[0043] 25. Vertical tail

[0044] 26 Fairing

[0045] 27. Trailing edge flap

[0046] 28 Central Axis

[0047] 29. Straight Line

[0048] 30 First intersection line

[0049] 31 Second intersection line

[0050] 32 Front section of fairing

[0051] 33 Rear section of fairing

[0052] 34. Load curves of the comparison scheme

[0053] 35 Load curves of this scheme

[0054] P0 Main wing junction position

[0055] P1 Upper trailing edge point

[0056] P2 Lower trailing edge point

[0057] P3 Intersection of front and rear segments

[0058] h1 height difference Detailed Implementation

[0059] The structure and technical effects of the fairing used in the flap mechanism according to the present invention will be described below with reference to the accompanying drawings.

[0060] It should be understood that the embodiments described in this specification cover only a portion of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this specification without inventive effort are within the scope of protection of this invention.

[0061] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings are intended to cover a non-exclusive inclusion. The singular forms "a," "described," and "the" as used in the embodiments of the invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0062] Based on the same orientational understanding, in the description of this invention, the terms "chord direction", "top", "bottom", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship when the aircraft is in normal flight. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0063] Figure 1 An aircraft with a fairing for a flap mechanism is shown. (Example) Figure 1 As shown, a large passenger aircraft typically consists of a nose 21, a fuselage 22, paired wings 23, and a rear body 24. The rear body 24 also forms a vertical stabilizer 25, and the wings 23 form trailing-edge flaps 27 extending outwards from the wings. To increase lift during takeoff and landing, the wings 23 are also equipped with fairings 26 for the flap mechanism. Since the connections and assembly relationships of these components are well known to those skilled in the art and are irrelevant to the inventive point of this application, they will not be described in detail herein.

[0064] Figure 2 It is a wing edge equipped with a conventional fairing Figure 1 The sectional view obtained after cutting along line AA.

[0065] like Figure 2 As shown, a conventional fairing for an aircraft flap mechanism includes: a flap fairing section (also called the forward fairing section) 32 located in front of the trailing edge of the aircraft's wing; and a flap fairing section (also called the aft fairing section) 33 located behind the trailing edge of the aircraft's wing. Furthermore, Figure 2 The figure also shows a cross-section of the wing, which is located within the area indicated by reference numeral c, where the axis is indicated by the dashed line 28.

[0066] In the top region of the forward section 32 and the aft section 33 of the fairing, the forward section 32 and the aft section 33 intersect at the main wing junction point P0, and the aft section 33 terminates at the upper trailing edge point P1. In the bottom region of the forward section 32 and the aft section 33 of the fairing, the forward section 32 and the aft section 33 intersect at the junction point P3, and the aft section 33 terminates at the lower trailing edge point P2.

[0067] A conventional fairing extends a straight line 29 from the junction point P3 of the fore-and-aft sections along the local airfoil chord direction. The lowest point of the rear section 33 of the fairing is located above this straight line 29. In other words, the lowest point of the rear section 33 is higher than the height of the junction point P3. Figure 2 As shown, the rear section 33 of the fairing is designed to bend monotonically upwards. In this case, the highest point of the rear section 33 is the lower trailing edge point P2 at the end of the rear section 33, and the lowest point is the junction point P3 between the front and rear sections. At this time, the lower trailing edge point P2 is above the straight line 29. If the height difference between the lower trailing edge point P2 and the junction point P3 is defined as h1, and the fact that the lower trailing edge point P2 is above the straight line 29 is defined as a positive value, then h1 > 0.

[0068] Figure 3 It shows having Figure 2 Lift loss due to the construction of a conventional fairing.

[0069] like Figure 3 As shown in the figure, this diagram compares the pressure coefficient distribution of a clean wing and a wing section equipped with conventional fairings. The red curve with hollow squares represents the pressure coefficient of a clean wing section without flap fairings, while the green curve with solid triangles represents the pressure coefficient of a wing section equipped with flap fairings. Figure 3 The x-axis represents the position x of the airfoil from the leading edge to the trailing edge, and the y-axis represents the surface pressure coefficient cp.

[0070] according to Figure 3 The pressure distribution comparison shown reveals that the flap fairing disrupts the original wing design's pressure distribution pattern, resulting in a significant reduction in wing load and a corresponding decrease in the local lift coefficient.

[0071] Figure 4 The wing edge is equipped with a fairing for the flap mechanism according to the present invention. Figure 1 The sectional view obtained after cutting along line AA.

[0072] like Figure 4As shown, similar to a conventional fairing, the fairing for an aircraft flap mechanism according to the present invention includes: a front fairing section 32 located in front of the trailing edge of the wing of the aircraft; and a rear fairing section 33 located behind the trailing edge of the wing of the aircraft, wherein the front fairing section 32 and the rear fairing section 33 intersect at the junction point P3 in the bottom region of the fairing 26.

[0073] Unlike conventional fairings, this fairing extends a straight line 29 from the junction point P3 of the fore-and-aft sections along the local airfoil chord direction. The lowest point of the rear section 33 of the fairing is located below or no higher than this straight line 29. In other words, the lowest point of the rear section 33 is at an altitude lower than or equal to the altitude of the junction point P3. Figure 4 As shown, the rear section 33 of the fairing is designed to bend downwards monotonically. In the bottom region of the fairing 26, the highest point of the rear section 33 is the junction point P3 between the front and rear sections, and the lowest point is the lower trailing edge point P2 at the end of the rear section 33. At this time, the lower trailing edge point P2 is located below the straight line 29. If the height difference between the lower trailing edge point P2 and the junction point P3 is defined as h1, and the location of the lower trailing edge point P2 above the straight line 29 is defined as a positive value, then h1 ≤ 0.

[0074] As a preferred embodiment, the absolute value of the height difference h1 can be designed to be less than or equal to 5% of the local airfoil chord length. Of course, those skilled in the art can also reasonably set the range of values ​​for the height difference h1 according to the actual situation, and such range should all fall within the protection scope of this invention.

[0075] See also Figure 4 The rear section 33 of the fairing intersects with the plane containing the local airfoil. The line of intersection located in the top region of the fairing 26 is defined as the first line of intersection 30, and the line of intersection located in the bottom region of the fairing 26 is defined as the second line of intersection 31. It can be seen that the first line of intersection 30 can be designed as a straight line or a convex curve, and is tangent to the main wing of the aircraft at the main wing junction point P0. Correspondingly, the second line of intersection 31 can be designed as a straight line or a concave curve, and is tangent to the front section 32 of the fairing at the junction point P3.

[0076] In a preferred embodiment, if the first intersection line 30 is a straight line, the surface at or near the main wing intersection position P0 can be designed as an arc-shaped surface or a roughly arc-shaped surface to ensure a smooth transition of curvature at or near the main wing intersection position P0.

[0077] Similarly, if the second intersection line 31 is a straight line, the surface at or near the intersection point P3 of the front and rear segments can be designed as an arc-shaped surface or a roughly arc-shaped surface to ensure a smooth transition of curvature at or near the intersection point P3 of the front and rear segments.

[0078] Figure 5It shows having Figure 4 The lift gain of the constructed fairing.

[0079] and Figure 3 Similarly, the figure shows a comparison of the pressure coefficient distributions of a wing with a conventional fairing and a wing with a fairing according to the invention, wherein the green curve with a solid triangle represents the pressure coefficient of the wing section with a conventional fairing, and the blue curve with a hollow circle represents the pressure coefficient of the wing section with a fairing according to the invention. Figure 5 The x-axis represents the position x of the airfoil from the leading edge to the trailing edge, and the y-axis represents the surface pressure coefficient cp.

[0080] and Figure 3 In comparison, by employing the fairing according to the present invention, the load loss on the lower surface of the trailing edge is somewhat compensated. Figure 3 Compared to conventional designs, the pressure distribution of the wing spanwise load is improved, and the induced drag is reduced by approximately 0.5 drag units.

[0081] Therefore, this invention utilizes the change in fairing shape along the flow direction to improve local pressure distribution. Compared with existing technologies, it can optimize the wingspan load of the aircraft, and not only significantly reduce lift loss, but also improve the wing circulation distribution during flight, both of which lead to improved aerodynamic efficiency.

[0082] Figure 6 The diagram shows a coordinate axis with wingspan on the horizontal axis and wingspan load on the vertical axis. Curve 34 represents the wing load curve of a conventional fairing, while curve 35 represents the wing load curve of the fairing according to the present invention. It can be seen that the load curve using the fairing according to the present invention further approaches... Figure 6 The ideal curve is obtained, so its effect is significantly better than that of using a conventional fairing.

[0083] While the structure and working principle of the fairing for the flap mechanism according to the present invention have been described above in conjunction with preferred embodiments and accompanying drawings, those skilled in the art should recognize that the above examples are merely illustrative and should not be construed as limiting the invention. Therefore, modifications and variations can be made to the invention within the spirit and scope of the claims, and all such modifications and variations will fall within the scope claimed by the claims.

Claims

1. A fairing (26) for an aircraft flap mechanism, comprising: The front section (32) of the fairing located in front of the trailing edge of the wing of the aircraft; as well as The rear section (33) of the fairing located behind the trailing edge of the wing of the aircraft. The front section (32) and the rear section (33) of the fairing meet at the junction point (P3) in the bottom region of the fairing (26). Wherein, the lowest point (P2) of the rear section (33) of the fairing is lower than or equal to the height of the junction point (P3) of the front and rear sections, the rear section (33) of the fairing is monotonically bent downwards, and in the bottom region of the fairing (26), the lowest point (P2) of the rear section (33) of the fairing is the lower trailing edge point (P2) of the rear section.

2. The fairing (26) as described in claim 1, characterized in that, The fairing (26) extends backward in a straight line (29) from the junction point (P3) of the front and rear sections along the local airfoil chord direction, and the lowest point (P2) of the rear section (33) of the fairing is not higher than the straight line (29).

3. The fairing (26) as described in claim 1, characterized in that, If the height difference between the lower trailing edge point (P2) of the rear segment and the junction point (P3) of the front and rear segments is h1, and the lower trailing edge point (P2) of the rear segment is defined as being above the straight line (29) as a positive value, then h1≤0.

4. The fairing (26) as described in claim 3, characterized in that, The absolute value of the height difference (h1) is less than or equal to 5% of the local airfoil chord length.

5. The fairing (26) as described in claim 1, characterized in that, The rear section (33) of the fairing intersects the plane of the local airfoil, and the first intersection line (30) obtained in the top region of the fairing (26) is a straight line or an outwardly convex curve, and is tangent to the main wing of the aircraft at the main wing junction position (P0).

6. The fairing (26) as described in claim 5, characterized in that, If the first intersection line (30) is a straight line, an arc surface is used near the main wing intersection position (P0) to ensure a smooth transition of curvature.

7. The fairing (26) as described in claim 5, characterized in that, The rear section (33) of the fairing intersects the plane of the local airfoil, and the second intersection line (31) obtained in the bottom region of the fairing (26) is a straight line or an inward curve, and is tangent to the front section (32) of the fairing at the junction point (P3) of the front and rear sections.

8. The fairing (26) as described in claim 7, characterized in that, If the second intersection line (31) is a straight line, an arc surface is used near the intersection point (P3) of the front and rear segments to ensure a smooth transition of curvature.

9. An aircraft equipped with a flap mechanism and a fairing (26) as claimed in any one of claims 1 to 8, wherein, The fairing (26) is used for the flap mechanism of the aircraft.

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