Leading edge slat and aircraft comprising such leading edge slat
By designing the transitional profile of the continuous convex curved surface of the first and second parts on the side end surfaces of the leading edge slat wing, the problem of maximum lift coefficient limitation caused by the end surface vortex in the prior art is solved, and the effect of delayed flow separation and improving the maximum lift coefficient is achieved.
Patent Information
- Application Number
- CN202510354574.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-24
- Publication Date
- 2025-06-10
AI Technical Summary
The existing leading edge slat design limits the maximum lift coefficient of the aircraft due to the existence of end surface vortex, causing the aircraft to stall in advance when flying at low speeds.
A new type of leading edge slit is designed, with the side end faces of which are divided into a first part and a second part and extending a continuous convex curved surface portion between the first part and the trailing edge of the slit to establish a curved surface transition profile from the slit end face to the trailing edge.
Through the slat end face vortex that falls off early, it weakens its induction on the fixed wing steps and adjacent areas, delays flow separation, and increases the maximum lift coefficient of the aircraft.
Smart Images
Figure CN120117166A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of aircraft structural design, and more particularly to a leading-edge slat. The present invention also relates to an aircraft including such a leading-edge slat. Background Art
[0002] When an aircraft takes off, various coefficients of the aircraft affect its flight speed. Among these coefficients, the maximum lift coefficient is a key parameter for the low-speed performance of the aircraft. Increasing the maximum lift coefficient enables the aircraft to take off and land at a lower flight speed, reducing the requirement for the length of the airport runway.
[0003] Modern large aircraft usually adopt wing structure lift augmentation devices such as leading-edge slats and trailing-edge flaps to increase the maximum lift coefficient during low-speed flight. After the leading-edge slat is opened, the airflow passes through the gap and adheres to the upper surface of the fixed wing, injecting energy into the upper surface flow, thereby delaying the flow separation and increasing the maximum lift coefficient.
[0004] The end faces of existing leading-edge slats usually adopt a flat or approximately flat design. However, after such leading-edge slats are opened, due to the pressure difference, vortices that wash upward (i.e., vortices that deflect upward around the slat), also known as "slat end face vortices", will be formed on the end faces on both sides of the slat. The slat end face vortices develop downstream and pass through the discontinuous steps formed on the fixed wing due to the opening of the slat. These fixed wing steps are often close to separation-sensitive areas such as the wing-body transition section, behind the nacelle suspension, and the wing tip of the aircraft wing. At this time, the upward induction of the end face vortices can easily trigger flow separation, causing the whole aircraft to stall in advance and restricting the increase of the maximum lift coefficient.
[0005] Since the existing leading-edge slat design is not conducive to the shedding of the end face vortices from the slat and has an adverse effect on the downstream flow, therefore, there is currently a need for a slat profile design that can minimize the upward washing effect of the end face vortices on the position of the fixed wing steps. Summary of the Invention
[0006] To solve the problem that the maximum lift coefficient of an aircraft is limited by the end face vortices of existing leading-edge slats, the present invention proposes a new type of leading-edge slat. By establishing a curved surface transition profile from the slat end face to the trailing edge, after the slat is deployed, the new aerodynamic profile can cause the slat end face vortices to shed in advance, effectively reducing the induction of the end face vortices on the fixed wing steps and adjacent areas. Moreover, the curved surface profile enables the slat to still maintain a relatively large chord length at the end face transition position, ultimately achieving the effect of suppressing separation and increasing the maximum lift coefficient.
[0007] Specifically, the leading-edge slat has an upper wing surface, a lower wing surface, and a side end surface. The upper wing surface defines a slat leading edge and a slat trailing edge, and the slat leading edge and the slat trailing edge define a slat plane. The contour of the side end surface is defined by the side edge of the upper wing surface and the side edge of the lower wing surface. Among them, the side end surface includes a first part and a second part. The first part extends from the slat leading edge. Among them, the second part is a continuous convex curved surface part that extends between the first part and the slat trailing edge.
[0008] In an embodiment of the present invention, the outer side end surface in the side end surface includes a first part and a second part.
[0009] In a preferred embodiment, the first part is a flat part.
[0010] In an embodiment, the first part is perpendicular to the slat plane.
[0011] In an embodiment, the second part is perpendicular to the slat plane.
[0012] Optionally, the second part extends at least 20% of the chord length of the slat in the chord length direction.
[0013] In an embodiment, the first part and the second part are continuous at their connection part. The continuous outer shape between the first part and the second part improves the effect of suppressing flow separation.
[0014] In an embodiment, the second part and the slat leading edge are continuous at their connection part. The continuous outer shape between the second part and the slat leading edge improves the effect of suppressing flow separation.
[0015] The present invention also relates to an aircraft, which includes the leading-edge slat as described above.
[0016] The additional features and advantages of the described leading-edge slat will be set forth in the detailed description below, and will be apparent to those skilled in the art from the following description or recognized by those skilled in the art from practicing the embodiments described herein. These descriptions include the following detailed description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] For the above purposes, the technical features of the present invention are clearly described in the following claims, and its advantages are obvious from the following detailed description with reference to the drawings. The drawings illustrate the preferred embodiments of the present invention by way of example, without limiting the scope of the inventive concept.
[0018] Figure 1 A partial schematic view of the leading-edge slat of an aircraft of the prior art is shown.
[0019] Figure 2 A schematic view of the flow at the leading-edge slat of an aircraft of the prior art is shown.
[0020] Figure 3 Shows a partial schematic view of a leading edge slat of an aircraft according to an embodiment of the present invention.
[0021] Figure 4 Partial schematic views of a leading edge slat of an aircraft according to an embodiment of the present invention are shown at different angles.
[0022] Figure 5 Shows a top view of a leading edge slat of an aircraft according to an embodiment of the present invention.
[0023] Figure 6 Shows a schematic view of the flow at the leading edge slat of an aircraft according to an embodiment of the present invention.
[0024] Figure 7 Shows a comparison chart of the maximum lift coefficient results between the leading edge slat of an aircraft in the prior art and the leading edge slat of an aircraft according to an embodiment of the present invention.
[0025] Reference numerals
[0026] 1, 1' upper wing surface
[0027] 2, 2' lower wing surface
[0028] 3 side end face
[0029] 4 slat leading edge
[0030] 5 slat trailing edge
[0031] 6 first part
[0032] 7 second part
[0033] 8 first connecting part
[0034] 9 second connecting part. Detailed implementation manners
[0035] The present invention will be further described in detail below with reference to the drawings and embodiments, but it is not used as a basis for any limitation to the present invention.
[0036] The term "leading edge" used herein refers to the edge of the wing that first contacts the oncoming flow. The straight slat leading edge is shown at the bottom in the Figure 5 top view, and the term "trailing edge" refers to the edge of the wing that last contacts the airflow. The straight slat trailing edge is shown at the top in the Figure 5 top view.
[0037] The term "slat plane" as used herein is used to describe the plane defined by the leading edge of the slat and the trailing edge of the slat. Note that the slat plane is not a specific structure, but is only defined for the convenience of describing the positions of the first part and the second part hereinafter.
[0038] The term "outer side" as used herein is used to describe the side facing away from the aircraft fuselage.
[0039] The term "chord length" as used herein is used to describe the distance from the leading edge to the trailing edge.
[0040] The term "chordwise station" as used herein is used to describe a specific position along the chord length of the wing
[0041] "A certain part is perpendicular to the slat plane" as described herein means that the perpendicular projection of this part on the slat plane is a line (not a plane) with endpoints.
[0042] The term "continuous" as used herein, unless otherwise explained, always means that at any point of the connection between two parts, the second derivative (curvature tensor) is continuous, that is, the curvature is continuous, so that the transition between the two parts is completely smooth.
[0043] The term "convex" as used herein means that a certain surface protrudes towards the outside of the aircraft structure relative to the tangent plane formed by its connection part.
[0044] The present invention relates to a leading edge slat profile, which divides the side end face of the leading edge slat into a first part and a second part, and designs the second part to be convex to increase the maximum lift coefficient of the aircraft. Those skilled in the art will understand that as long as there is a need, this design can be not limited to the leading edge slat, but can be applied to any other slat or even other wing structures.
[0045] Refer to Figure 1 and Figure 2 , a partial schematic diagram of the leading edge slat of an aircraft of the prior art and the flow at the leading edge slat is shown. The leading edge slat of the prior art has an upper wing surface 1, a lower wing surface 2 and a side end face 3, and the contour of the side end face 3 is defined by the side edges of the upper wing surface 1 and the lower wing surface 2. The shape contours of the upper wing surface 1 and the lower wing surface 2 are known to those skilled in the art and will not be described in detail herein.
[0046] From Figure 2 it can be seen that in such a leading edge slat, vortices usually attach to the side end face 3, forming an upward wash of the air flow, causing the flow separation to occur earlier at the fixed wing downstream of this area, reducing the maximum lift coefficient.
[0047] Refer to Figures 3 - 5, To address this issue, a leading-edge slat according to an embodiment of the present invention is provided. As shown in the figure, the leading-edge slat has an upper wing surface 1', a lower wing surface 2', and side end faces. The upper wing surface 1' defines a slat leading edge 4 and a slat trailing edge 5, and the slat leading edge 4 and the slat trailing edge 5 define a slat plane. The contour of the side end face is defined by the side edges of the upper wing surface 1' and the lower wing surface 2'. Different from the side end face 3 of the prior art (refer to Figure 1 or Figure 5 ), in the embodiment of the present invention, the side end face is divided into a first part 6 and a second part 7. The first part 6 extends from the slat leading edge 4 to a first connection portion 8, where the first part 6 meets the second part 7, and the second part 7 extends from the first connection portion 8 to a second connection portion 9, where the second part 7 meets the slat trailing edge 5.
[0048] In the embodiment of the present invention, the outer side end face (i.e., the side end face closer to the wing tip) of the two side end faces of the slat has the first part 6 and the second part 7 as shown. In another embodiment, both side end faces of the slat can have the above-mentioned first part and second part. In yet another embodiment, the inner side end face (i.e., the side end face closer to the wing root) of the two side end faces of the slat can have the above-mentioned first part and second part.
[0049] In one embodiment, the first part 6 is preferably a planar part and perpendicular to the slat plane (refer to Figure 5 ), which can maintain a good aerodynamic shape of the slat. However, the present invention does not limit the shape contour of the first part 6. For example, in other embodiments, the first part 6 can also be a curved surface part. Further, the first part can also be continuous with the second part to jointly form a continuous convex curved surface part, such that the entire side end face is a convex curved surface (in other words, there is no "planar part" visually). In a further embodiment, the first part 6 can also be inclined with respect to the slat plane.
[0050] In the embodiment of the present invention, the second part 7 is a continuous convex curved surface part that extends between the first part and the slat trailing edge and bulges towards the outside of the slat. The second part 7 can also be perpendicular to the slat plane (refer to Figure 5 ). It should be understood that in other variant embodiments, the second part 7 can also be inclined with respect to the slat plane.
[0051] Considering that in the prior art, end face vortex shedding usually occurs at the chordwise station near the trailing edge, such as the 95%-100% position (defining the slat leading edge as the 0% chordwise station; the slat trailing edge as the 100% chordwise station), the second part 7 can extend at least 20%, at least 30%, or at least 40% of the chord length of the slat in the chord length direction to satisfy the early shedding of the slat end face vortex at the desired position.
[0052] Preferably, the first part 6 is continuous with the second part 7 at the first connecting part 8, that is, there is no sudden change in curvature. Similarly preferably, the second part 7 is continuous with the leading edge of the slat 4 at the second connecting part 9. The continuous profile improves the effect of suppressing flow separation.
[0053] From Figure 6 It can be seen that in the leading edge slat of the present invention, the slat end face vortex has left the end face in advance, thereby weakening the upwash effect of the end face vortex on the position of the fixed wing step, achieving the effect of delaying stall and increasing the maximum lift coefficient of the whole aircraft.
[0054] Figure 7 The figure shows a comparison chart of the maximum lift coefficient results of the leading edge slat of an aircraft of the prior art and the leading edge slat of an aircraft according to an embodiment of the present invention. The solid line represents the leading edge slat representing an embodiment of the present invention, the dashed line represents the leading edge slat of the prior art, the horizontal axis represents the angle of attack (α, unit: degree) of the aircraft during takeoff, and the vertical axis represents the maximum lift coefficient (C L L). It can be seen that at a relatively large angle of attack, the maximum lift coefficient of the aircraft is significantly improved.
[0055] It should be understood that in other embodiments, the side end face can also have different designs. For example, in some embodiments, the side end face can be divided into a first part, a second part, a third part, etc.
[0056] The present invention proposes a new leading edge slat profile. By establishing a curved surface transition profile from the slat end face to the trailing edge, after the slat is deployed, the new aerodynamic profile can make the slat end face vortex shed in advance, effectively reducing the induction of the end face vortex on the fixed wing step and the adjacent area, and the curved surface profile enables the slat to still maintain a relatively large chord length at the end face transition position, ultimately achieving the effect of suppressing separation and increasing the maximum lift coefficient.
[0057] Although the structure of the present invention has been described above in combination with preferred embodiments, those of ordinary skill in the art in this technical field should recognize that the above examples are only for illustration and cannot be used as a limitation to the present invention. Therefore, the present invention can be modified and varied, and these modifications and variations will all fall within the scope defined by the appended claims of this application.
Claims
1. A leading edge slat, the leading edge slat comprising an upper wing surface, a lower wing surface and a side end surface, the upper wing surface defines a slat leading edge and a slat trailing edge, the slat leading edge and the slat trailing edge define a slat plane, and the profile of the side end surface is defined by the side edge of the upper wing surface and the side edge of the lower wing surface, It is characterized in that At least one of the side end surfaces includes a first portion and a second portion, the first portion extending from the slat leading edge, wherein the second portion is a continuous convexly curved portion extending between the first portion and the slat trailing edge.
2. The leading edge slat according to claim 1, characterized in that: The outer side end surface of the side end surface includes the first portion and the second portion.
3. The leading edge slat according to claim 1, characterized in that: The first portion is continuous with the second portion to form a continuous convex curved portion.
4. The leading edge slat according to claim 1, characterized in that: The first portion is a planar portion.
5. The leading edge slat according to claim 1, characterized in that: The first portion is perpendicular to the slat plane.
6. The leading edge slat according to claim 1, characterized in that: The second portion is perpendicular to the slat plane.
7. The leading edge slat according to claim 1, characterized in that: The second portion extends in the chord direction by at least 20% of the chord length of the slat.
8. The leading edge slat according to claim 1, characterized in that: The first portion and the second portion are continuous at their connection portion.
9. The leading edge slat according to claim 1, characterized in that: The second portion is continuous with the slat leading edge at their connection.
10. An aircraft comprising the leading edge slat according to any one of claims 1 to 9.