High-lift-drag-ratio low-speed airfoil profile and Evtol aircraft with high-lift-drag-ratio low-speed airfoil profile

Abstract

The invention discloses a high-lift-drag-ratio low-speed airfoil profile and an Evtol aircraft with the same, and relates to the technical field of airfoil profile design. Comprising an airfoil profile body, the maximum camber of the airfoil profile body is 4%-4.5%, the maximum camber position is 45%-50%, the maximum thickness of the airfoil profile body is 15%-17%, and the maximum thickness position is 30%-35%. The airfoil profile body has the beneficial effects that the provided airfoil profile body has the high lift-drag ratio, and the take-off performance of the Evtol aircraft is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of airfoils, and in particular to a low-speed airfoil with a high lift-to-drag ratio and an eVTOL aircraft having the same. Background Art

[0002] The basic airfoil (low-speed airfoil) commonly used in eVTOL aircraft has a maximum thickness of 15% - 19%, a maximum thickness position of 25% - 40%, a maximum camber of 4% - 6%, and a maximum camber position of 30% - 50%. Such a basic airfoil with a relatively large leading-edge radius has the characteristics of a large lift-to-drag ratio, a high maximum lift coefficient, a low minimum drag coefficient, a wide low-drag range, and a gentle stall process. The above performance coefficients of the low-speed airfoil determine the takeoff performance of the eVTOL aircraft. In order to improve the takeoff performance of the eVTOL aircraft, it is necessary to improve the lift-drag characteristics of the airfoil, and try to ensure a relatively large laminar flow region, so as to reduce the frictional drag of the airfoil, increase the lift-to-drag ratio, and further improve the takeoff performance of the eVTOL aircraft. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a low-speed airfoil with a high lift-to-drag ratio and an eVTOL aircraft having the same, which has relatively high takeoff performance.

[0004] The present invention provides a low-speed airfoil with a high lift-to-drag ratio, including an airfoil body. The maximum camber of the airfoil body is 4% - 4.5%, the maximum camber position is 45% - 50%, the maximum thickness is 15% - 17%, and the maximum thickness position is 30% - 35%.

[0005] Optionally, a camber reversal section that bends towards the upper surface of the airfoil body is provided on the lower surface of the region of the airfoil body near the trailing edge.

[0006] Optionally, the camber reversal section includes a front section and a rear section. In the direction of the airfoil body's lower surface extending from the leading edge to the trailing edge of the airfoil body, the front section gradually inclines towards the direction close to the upper surface of the airfoil body; the rear section is connected to the front section, and in the direction of the airfoil body's lower surface extending from the leading edge to the trailing edge of the airfoil body, the rear section gradually inclines towards the direction away from the upper surface of the airfoil body.

[0007] Optionally, the front section of the camber reversal section extends in the shape of a cubic parabola, the rear section is symmetrically distributed with the front section, and the curvature at the connection of the front section and the rear section is continuous.

[0008] Optionally, the included angle between the cubic parabola presented by the shapes of the front section and the rear section of the camber reversal section and the chord of the airfoil body is 1° - 5°.

[0009] Optionally, the position of the reverse camber section is 85% - 100%.

[0010] The present invention also provides an eVTOL aircraft, including the high lift - to - drag ratio low - speed airfoil as described above.

[0011] The beneficial effects of the present invention are as follows: By designing the maximum camber, the position of the maximum camber, the maximum thickness, and the position of the maximum thickness of the airfoil body, the airfoil body has a relatively large lift - to - drag ratio. Description of the Drawings

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0013] Figure 1 It is a schematic structural diagram of an existing basic airfoil.

[0014] Figure 2 It is a schematic structural diagram of a high lift - to - drag ratio low - speed airfoil of the present invention.

[0015] Figure 3 It is a schematic diagram of the airfoil CFD grid topology and boundary - layer grid of a high lift - to - drag ratio low - speed airfoil of the present invention.

[0016] Figure 4 It is a comparison diagram of the drag coefficient curves between the high lift - to - drag ratio low - speed airfoil provided by the present invention and the existing basic airfoil.

[0017] Figure 5 It is a comparison diagram of the lift coefficient curves between the high lift - to - drag ratio low - speed airfoil provided by the present invention and the existing basic airfoil.

[0018] Figure 6 It is a comparison diagram of the lift - to - drag ratio curves between the high lift - to - drag ratio low - speed airfoil provided by the present invention and the existing basic airfoil.

[0019] In the figure: Airfoil body 10, reverse camber section 11, front section 111, rear section 112, leading edge 12, trailing edge 13. Detailed Embodiments

[0020] The following will describe in detail specific embodiments of the present invention with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the description of the present invention without creative efforts fall within the scope of protection of the present invention.

[0021] Unless otherwise clearly defined and limited, terms such as "set", "installed", "connected", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0022] The orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is customarily placed during use. It is only for the convenience of description and simplification of the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0023] Terms such as "first", "second", "third", etc. are only used to distinguish elements with similar attributes, rather than indicating or implying relative importance or a specific order.

[0024] The term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion. In addition to the listed elements, it may also include other elements not expressly listed.

[0025] As Figure 1 shown, Figure 1 is an existing basic airfoil, with a maximum thickness of 15% - 19%, a maximum thickness position of 25% - 40%, a maximum camber of 4% - 6%, and a maximum camber position of 30% - 50%.

[0026] Example 1: As Figure 2 shown, this example provides a high lift-to-drag ratio low-speed airfoil, including an airfoil body 10. The maximum camber of the airfoil body 10 is 4%, the maximum camber position is 45%, the maximum thickness is 15%, and the maximum thickness position is 30%.

[0027] Compared with the existing basic airfoil, in the airfoil body 10 provided in this embodiment, the maximum curvature of the airfoil body 10 is 4%, which can improve the maximum lift coefficient of the airfoil body 10. The maximum curvature position of the airfoil body 10 is 45%, which is conducive to enhancing the stability of the boundary layer of the airfoil body 10 close to the trailing edge 13. The maximum lift coefficient is slightly reduced, but a relatively gentle speed characteristic can be obtained. In addition, the maximum thickness of the airfoil body 10 is 15%, which can reduce the resistance of the airfoil body 10. At the same time, the maximum thickness position of the airfoil body 10 is 30%, which can make the minimum pressure position of the airfoil body 10 backward, and further make the pressure distribution on the upper surface of the airfoil body 10 tend to be flat, thereby shortening the range of action of the adverse pressure gradient. Finally, within the range of about 40% of the chord length of the airfoil body 10, there is an obvious favorable pressure gradient, the flow is always accelerating, and the laminar flow area is wide.

[0028] The lower surface of the airfoil body 10 near the trailing edge 13 is provided with a recurved section 11 that is curved toward the upper surface of the airfoil body 10. By providing the recurved section 11 at the lower surface of the airfoil body 10 near the trailing edge 13, a greater positive pressure than the existing basic airfoil can be generated, so that the lift of the rear part of the airfoil body 10 is increased, thereby generating a greater forward component, reducing the pressure difference drag, and improving the lift-to-drag ratio of the airfoil body 10. The position of the recurved section is 85%, that is, the ratio of the distance of the recurved section 11 from the leading edge of the airfoil body 10 to the chord length.

[0029] Specifically, the reverse curved section 11 includes a front section 111 and a rear section 112. The front section 111 gradually tilts toward the upper surface of the airfoil body 10 in the direction extending from the leading edge 12 to the trailing edge 13 of the airfoil body 10 on the lower surface of the airfoil body 10. The rear section 112 is connected to the front section 111. The rear section 112 gradually tilts away from the upper surface of the airfoil body 10 in the direction extending from the leading edge 12 to the trailing edge 13 of the airfoil body 10 on the lower surface of the airfoil body 10. The front section 111 and the rear section 112 are symmetrically distributed. The position of the reverse curved section 11 is defined by the farthest point of the rear section 111 from the upper surface of the airfoil body 10 as a reference point.

[0030] The front section 111 of the recurved section 11 extends in the shape of a cubic parabola, the rear section 112 is symmetrically distributed with the front section 111, and the curvature of the connection between the front section 111 and the rear section 112 is continuous. The angle between the cubic parabola presented by the shapes of the front section 111 and the rear section 112 of the recurved section 11 and the chord of the airfoil body 10 is 1°.

[0031] Embodiment 2: Figure 2 As shown, the airfoil body 10 provided in this embodiment has a maximum curvature of 4.2%, a maximum curvature position of 47%, a maximum thickness of 16%, and a maximum thickness position of 32%.

[0032] Compared with the existing basic airfoil, in the airfoil body 10 provided in this embodiment, the maximum camber of the airfoil body 10 is 4.2%, which can improve the maximum lift coefficient of the airfoil body 10. The position of the maximum camber of the airfoil body 10 is 47%, which is beneficial to enhancing the stability of the boundary layer of the part of the airfoil body 10 near the trailing edge 13. The maximum lift coefficient is slightly reduced, but a relatively gentle speed characteristic can be obtained. And the maximum thickness of the airfoil body 10 is 16%, which can reduce the drag of the airfoil body 10. At the same time, the position of the maximum thickness of the airfoil body 10 is 32%, which can make the position of the minimum pressure of the airfoil body 10 move backward, further making the pressure distribution on the upper surface of the airfoil body 10 tend to be flat, thereby shortening the action range of the adverse pressure gradient. Finally, there is an obvious favorable pressure gradient within about 40% of the chord length of the airfoil body 10, and the flow is always accelerating, and the laminar flow region has a wide range. The position of the camber reversal section 11 is 92%, that is, the ratio of the distance from the camber reversal section 11 to the leading edge of the airfoil body 10 to the chord length. The angles between the cubic parabolas presented by the front section 111 and the rear section 112 of the camber reversal section 11 and the chord of the airfoil body 10 are 3°. Other parts of this embodiment are the same as those of Embodiment 1 and will not be elaborated here.

[0033] Embodiment 3: As Figure 2 shown, for the airfoil body 10 provided in this embodiment, the maximum camber of the airfoil body 10 is 4.5%, the position of the maximum camber is 50%, the maximum thickness is 17%, and the position of the maximum thickness is 35%.

[0034] Compared with the existing basic airfoil, in the airfoil body 10 provided in this embodiment, the maximum camber of the airfoil body 10 is 4.5%, which can improve the maximum lift coefficient of the airfoil body 10. The position of the maximum camber of the airfoil body 10 is 50%, which is beneficial to enhancing the stability of the boundary layer of the part of the airfoil body 10 near the trailing edge 13. The maximum lift coefficient is slightly reduced, but a relatively gentle speed characteristic can be obtained. And the maximum thickness of the airfoil body 10 is 17%, which can reduce the drag of the airfoil body 10. At the same time, the position of the maximum thickness of the airfoil body 10 is 35%, which can make the position of the minimum pressure of the airfoil body 10 move backward, further making the pressure distribution on the upper surface of the airfoil body 10 tend to be flat, thereby shortening the action range of the adverse pressure gradient. Finally, there is an obvious favorable pressure gradient within about 40% of the chord length of the airfoil body 10, and the flow is always accelerating, and the laminar flow region has a wide range. The position of the camber reversal section 11 is 100%, that is, the ratio of the distance from the camber reversal section 11 to the leading edge of the airfoil body 10 to the chord length. The angles between the cubic parabolas presented by the front section 111 and the rear section 112 of the camber reversal section 11 and the chord of the airfoil body 10 are 5°. Other parts of this embodiment are the same as those of Embodiment 1 and will not be elaborated here.

[0035] In summary, the high lift-to-drag ratio low-speed airfoil provided in this embodiment has a relatively high lift-to-drag ratio.

[0036] As Figure 3 shown, Figure 3 This is a schematic diagram of the airfoil CFD mesh topology and boundary layer mesh of the high lift-to-drag ratio low-speed airfoil provided in this application. In the figure, the total number of meshes is approximately 120,000, the height of the first layer of meshes is 0.001 mm, the mesh growth rate is 1.15, the number of boundary layer layers N = 76, and the mesh topology is an O-type topology.

[0037] As Figures 4 to 6 shown, Figure 4 、 Figure 5 and Figure 6 are respectively the comparison diagrams of the drag coefficient curves, lift coefficient curves, and lift-to-drag ratio curves of the high lift-to-drag ratio low-speed airfoil and the basic airfoil provided in this application. It can be seen from the figure that at the same angle of attack, the drag coefficient of the high lift-to-drag ratio low-speed airfoil provided in this application is lower than that of the basic airfoil, the lift coefficient is higher than that of the basic airfoil, and the lift-to-drag ratio is higher than that of the basic airfoil. Therefore, the lift-to-drag ratio of the high lift-to-drag ratio low-speed airfoil provided in this application has been greatly improved compared with the basic airfoil.

[0038] This embodiment also provides an eVTOL aircraft, including the high lift-to-drag ratio low-speed airfoil as described above. In the case where the above-mentioned high lift-to-drag ratio low-speed airfoil has a relatively high lift-to-drag ratio, it can fully improve the takeoff performance of the eVTOL aircraft.

[0039] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A high lift-to-drag ratio low-speed airfoil, characterized in that: The airfoil body (10) comprises a maximum camber of 4%-4.5%, a maximum camber position of 45%-50%, a maximum thickness of 15%-17%, and a maximum thickness position of 30%-35%.

2. The high lift-to-drag ratio low-speed airfoil according to claim 1, characterized in that: The lower surface of the airfoil body (10) is provided with a reverse curved section (11) that curves towards the upper surface of the airfoil body (10).

3. The high lift-to-drag ratio low-speed airfoil according to claim 2, characterized in that: The reverse curved section (11) comprises a front section (111) and a rear section (112); the front section (111) is gradually inclined in a direction approaching the upper surface of the airfoil body (10) in a direction extending from the leading edge (12) of the airfoil body (10) to the trailing edge (13) on the lower surface of the airfoil body (10); and the rear section (112) is connected to the front section (111); the rear section (112) is gradually inclined in a direction away from the upper surface of the airfoil body (10) in a direction extending from the leading edge (12) of the airfoil body (10) to the trailing edge (13) on the lower surface of the airfoil body (10).

4. The high lift-to-drag ratio low-speed airfoil according to claim 3 is characterized in that: The front section (111) of the reverse curved section (11) extends in the shape of a cubic parabola, the rear section (112) is symmetrically distributed with the front section (111), and the curvature of the connection between the front section (111) and the rear section (112) is continuous.

5. The high lift-to-drag ratio low-speed airfoil according to claim 4, characterized in that: The front section (111) and the rear section (112) of the recurved section (11) present a cubic parabola whose included angle with the chord of the airfoil body (10) is 1°-5°.

6. The high lift-to-drag ratio low-speed airfoil according to claim 2, characterized in that: The position of the reverse bending section is 85%-100%.

7. An Evtol aircraft, characterized in that: It comprises a high lift-to-drag ratio low-speed airfoil as described in any one of claims 1-6.

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