Fin-based aircraft flap and method of designing the same

Abstract

The application discloses a fin-based aircraft flap and a design method thereof, and belongs to the technical field of aircraft design. The application solves the problem of poor noise reduction effect and difficulty in maintenance of the traditional aircraft flap and the design method thereof in the prior art. The application provides a fin-based aircraft flap, which comprises a main wing, an inboard trailing edge flap, an outboard trailing edge flap and a fin structure. The inboard trailing edge flap and the outboard trailing edge flap are connected with the main wing, and the fin structure is installed inside a side edge of the outboard trailing edge flap, so that a fin-shaped ventilation structure is formed on the side edge of the flap. The fin structure is composed of fins, the curvature of the outer contour surface of the fin structure is consistent with the curvature of the original flap surface, and the span length of the fins is linearly distributed. The application effectively reduces the noise of the aircraft body and can be applied to the design of a noise reduction flap.

Description

TECHNICAL FIELD

[0001] The present application relates to a fin-based aircraft flap and a design method thereof, and belongs to the technical field of aircraft design. BACKGROUND

[0002] At present, the problem of aerodynamic noise is one of the key problems in the development process of large passenger aircraft, which is directly related to whether the large passenger aircraft can be certified for airworthiness. Most large passenger aircraft adopt high-lift configurations with trailing edge flaps to meet the lift-drag ratio characteristics during take-off and landing stages and suppress stall, while the aerodynamic noise generated by the trailing edge flaps increases the overall noise level of the large passenger aircraft. The high-intensity side edge vortex pair formed by the pressure difference on the upper and lower surfaces of the flap side edge occupies a large proportion of the fuselage noise. Due to the instability of the high-intensity side edge vortex pair and the mutual interference with the solid wall, unsteady pressure pulsation is induced, resulting in an increase in noise level. Therefore, it is urgent to develop an efficient and stable noise control method to solve the problem of flap side edge noise.

[0003] In the prior art, the flap side edge noise reduction technology mainly includes active control and passive control, and the core idea of both is to eliminate or weaken the flap side edge vortex structure. The active control method controls the vortex structure by injecting energy into the flow field, including air blowing control, plasma, etc. The passive control technology reduces noise by changing and modifying the side edge configuration, and the methods mainly include: side edge flap end plate, installation of porous material, continuous linear method and micro perturbation fin, etc. However, the active control technology has limited noise reduction effect, and it needs additional driving mechanism or storage space. The side edge flap end plate and the continuous linear method increase the additional weight and manufacturing difficulty of the aircraft, and the installation of porous material and the micro perturbation fin method affects the aerodynamic performance of the aircraft and is not easy to maintain.

[0004] In view of the above, a fin-based aircraft flap and a design method thereof are needed. SUMMARY

[0005] In the following, a brief summary of the present application is given in order to provide a basic understanding of some aspects of the present application. It should be understood that this summary is not a comprehensive summary of the present application. It is not intended to determine the key or important parts of the present application, nor to limit the scope of the present application. Its purpose is only to give some concepts in a simplified form as a prelude to the more detailed description discussed later.

[0006] In view of this, in order to solve the problem of poor noise reduction effect and difficult maintenance of the traditional aircraft flap and its design method in the prior art, the present application provides a fin-based aircraft flap and a design method thereof.

[0007] The technical scheme one is as follows: a fin-based aircraft flap, comprising a main wing, a trailing edge inner side flap, a trailing edge outer side flap and a fin structure.

[0008] The rear edge inner flap, the rear edge outer flap and the main wing are connected, and the fin structure is installed inside the side edge of the rear edge outer flap, so that the side edge of the flap forms a fin-shaped ventilation structure.

[0009] The fin structure is composed of a fin.

[0010] Further, the curvature of the outer contour surface of the fin structure is consistent with the curvature of the original flap surface, and the spanwise length of the fin is linearly distributed.

[0011] Technical solution two is as follows: An aircraft flap based on a fin and a design method thereof, for designing the aircraft flap based on the fin in technical solution one, comprising the following steps:

[0012] S1. Determine the chordwise installation length and installation position of the fin according to the chord length of the end surface airfoil of the rear edge outer flap;

[0013] S2. Determine the maximum spanwise length of the flap rear edge fin and the maximum spanwise length of the flap front edge fin according to the thickness of the end surface airfoil of the rear edge outer flap, and complete the design of the fin-based flap.

[0014] Further, in S1, the chordwise distance between the airfoil leading edge point and the starting installation position of the fin is represented as:

[0015] ;

[0016] wherein, is the chord length of the end surface airfoil of the rear edge outer flap;

[0017] The chordwise distance between the airfoil trailing edge point and the ending installation position of the fin is represented as:

[0018] ;

[0019] The chordwise installation length of the fin is represented as:

[0020] .

[0021] Further, in S2, the maximum spanwise length of the flap rear edge fin is represented as:

[0022] ;

[0023] wherein, is the maximum thickness of the end surface airfoil of the rear edge outer flap;

[0024] The maximum spanwise length of the flap front edge fin is represented as:

[0025] .

[0026] The beneficial effects of the present invention are as follows: The present invention proposes an aircraft flap based on fins and its design method. Fins are installed on the basis of conventional wings to replace the side edges of the flaps, so that the side edges of the flaps form a fin-shaped ventilation structure. The fins help to suppress the generation and development of large-scale vortex structures on the side edges, thereby reducing the noise of the aircraft. The fin-shaped structure has the characteristics of not interfering with the flaps' retraction and extension, and does not lose the aerodynamic performance of the lift enhancement device, and is more practical in engineering. Specifically: (1) The present invention is based on the noise generation mechanism of the flap side edges. The high-intensity side edge vortex pair structure is its main noise source. By adopting a fin-shaped ventilation structure to design the side edges of the flaps into a hollow form, the large-scale vortex structure is effectively decomposed into a small-scale vortex structure, suppressing the formation and development of side edge vortex pairs, weakening the vortex intensity of the side edge vortex, and achieving the purpose of reducing noise; (2) The present invention The outer surface profile of the fin-shaped structure of the invention has the same surface curvature as the original wing. In addition, the chordal installation length of the fin and the maximum spanwise length of the fin are related to the airfoil size of the flap side edge end face and the vortex size of the flap side edge. That is, the aerodynamic shape is maximized to ensure consistency with the original shape. Therefore, the aircraft flap based on the fin can reduce noise while also having good aerodynamic performance. (3) Compared with the active control method, the present invention adopts passive control, that is, there is no need to inject external energy into the flow field and there is no additional drive structure, which is easier to implement in engineering. Compared with other passive control measures, the fin-shaped structure is installed inside the flap side edge, without generating additional weight, which saves more material costs. In addition, the flap with the fin-shaped structure can be freely extended and retracted during takeoff, landing and cruise, which is more applicable and feasible. Attached Figure Description

[0027] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1 This is a schematic diagram of a fin-based aircraft flap configuration;

[0029] Figure 2 A cross-sectional view of a fin-based aircraft flap configuration (AA section).

[0030] Figure 3 This is a schematic cross-sectional view of the fin-like structure;

[0031] Figure 4 This is a schematic diagram of the overall fin-like structure;

[0032] Figure 5 This is a schematic diagram comparing the aerodynamic performance of aircraft.

[0033] Figure 6 Contrast diagram of vorticity characteristics of a basic configuration and a fin-based aircraft flap configuration, wherein (a) is a contrast diagram of vorticity characteristics of the basic configuration, and (b) is a contrast diagram of vorticity characteristics of the fin-based aircraft flap configuration;

[0034] Figure 7 Contrast diagram of observation point spectrum curves, (a) is a diagram of near-field observation point spectrum curves, and (b) is a diagram of far-field observation point spectrum curves;

[0035] Figure 8 Flow diagram of a design method of a fin-based aircraft flap.

[0036] The figure marks: 1. aircraft; 2. fuselage; 3. wing; 4. engine; 5. leading edge inboard slat; 6. leading edge outboard slat; 7. main wing; 8. trailing edge inboard flap; 9. trailing edge outboard flap; 10. first sliding rail; 11. second sliding rail; 12. pylon; 13. fin structure; 14. fin. DETAILED DESCRIPTION

[0037] In order to make the technical solutions and advantages in the embodiments of the present application clearer, the exemplary embodiments of the present application are further described in detail below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, and are not an exhaustive enumeration of all embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0038] Embodiment 1: Reference Figures 1-8 In this embodiment, a fin-based aircraft flap includes a main wing 7, a trailing edge inboard flap 8, a trailing edge outboard flap 9, and a fin structure 13.

[0039] The trailing edge inboard flap 8 and the trailing edge outboard flap 9 are connected to the main wing 7, and the fin structure 13 is installed inside the side edge of the trailing edge outboard flap 9, so that the side edge of the flap forms a fin-shaped ventilation structure.

[0040] The fin structure 13 is composed of a fin 14.

[0041] Further, the outer contour surface curvature of the fin structure 13 is consistent with the original flap surface curvature, and the spanwise length of the fin 14 is linearly distributed.

[0042] Specifically, the upper and lower surfaces and the side surface of the fin-based aircraft flap are in a hollow form, and the side surface of the fin structure 13 and the end surface of the side edge of the flap are in the same vertical plane.

[0043] The shape of the fin 14 has diversity, which can be a cuboid, a cylinder, etc.

[0044] refer to Figure 1 The aircraft 1 includes a fuselage 2, a wing 3 and an engine 4. The wing 3 includes an inner leading edge slat 5, an outer leading edge slat 6, a main wing 7, an inner trailing edge flap 8, and an outer trailing edge flap 9. The inner leading edge slat 5 and the outer leading edge slat 6 extend and retract along a first slide rail 10 mounted on the main wing 7. The inner trailing edge flap 8 and the outer trailing edge flap 9 extend and retract along a second slide rail 11 mounted on the main wing 7. The fin structure 13 is composed of fins 14 and is mounted on the scissor-slit side of the outer trailing edge flap 9. The engine 4 is mounted below the main wing 7 via a pylon 12 that bears the weight and thrust of the engine.

[0045] refer to Figure 2 Point C is the leading edge of the airfoil, point D is the trailing edge of the airfoil, and points E and F represent the airfoil thickness. The chordal distance between the midpoints of points E and F defines the installation length of the fin structure 13. To avoid sacrificing the aerodynamic performance of the lift enhancement device, the chordal distance between points E and C, i.e., the chordal distance between the leading edge of the airfoil and the initial installation position of the fin, is also defined. e =0.15 c =0.026m, where m is the unit, representing the chordal distance between points F and D, i.e., the chordal distance between the trailing edge of the airfoil and the fin termination installation position. f =0.15 c =0.026m, chordal installation length of fin structure 13 s Airfoil chord length at the flap end face c Maintaining 70% of the original aerodynamic shape at the leading and trailing edges of the outer trailing edge flap 9 ensures stable airflow at the leading edge and reliable trailing edge structure. It should be noted that the chordal distance between points E and C... e chordal distance between point F and point D f These values ​​can be different. Points E and F are only used to indicate the start and end installation positions of the fin structure 13 and should not be considered as other limitations.

[0046] refer to Figure 3 The fin-like structure 13 is composed of a set of tiny fins 14. It should be understood that the smaller the size of the fins 14 and the smaller the spacing between adjacent fins 14, the more air passages are formed by the fin-like structure 13, which is more conducive to decomposing large-scale vortex structures into small-scale vortex structures. In this embodiment, l and d These are the length and width of fin 14, respectively. , , q and n These represent the left-right and top-bottom distances between the center points of adjacent fin 14, respectively. , It should be noted that, in order not to change the aerodynamic shape of the high-lift device, the outer contour line of the fin structure 13 is consistent with the original flap outer contour line, and the dashed line is the original flap outer contour line;

[0047] Reference Figure 4 The fin 14 is arranged inside the outboard flap 9 at the trailing edge, and the span length of the fin 14 is h Specifically: , The span length of the fin 14 is h The size of the side edge vortex is positively correlated, that is, the fin 14 has a shorter span length at the leading edge of the flap and a longer span length at the trailing edge of the flap. In addition, in order not to affect the aerodynamic performance of the high-lift device, in the embodiment, the value of is limited to 1.5 times the maximum thickness of the outboard flap end surface airfoil, The value of is It should be noted that the fin structure 13 can be adjusted to other forms according to user requirements, such as using a cylindrical fin to form a fin structure;

[0048] Reference Figure 5 The aerodynamic force of the aircraft flap based on the fin is not much different from the base configuration, and the fin has little effect on the aerodynamic performance of the aircraft high-lift device. BASE_CL and BASE_CD represent the lift coefficient and drag coefficient of the base configuration, respectively, and FINS_CL and FINS_CD represent the lift coefficient and drag coefficient of the aircraft flap based on the fin, respectively.

[0049] Reference Figure 6 The base configuration has a clear double-vortex structure, and at about 1 / 2 of the flap chord length, the two vortices merge to form a single-vortex structure. In the aircraft flap based on the fin, the fin 14 decomposes the large-scale vortex structure of the flap side edge into a small-scale vortex structure, effectively inhibiting the generation and development of the double-vortex structure of the flap side edge, and significantly reducing the vorticity intensity of the flap side edge. VorticityMagnitude represents the vorticity.

[0050] Reference Figure 7 The fin 14 can reduce the near-field noise in the full frequency range, reduce the sound energy of the low frequency and medium frequency of the far-field noise, and reduce the total sound pressure level at the far-field observation point by 1dB in the range of 80Hz-20kHz. BASE is the base configuration, FINS is the aircraft flap based on the fin, PSD is the power spectral density, unit: dB / Hz, Frequency is the frequency, unit: Hz.

[0051] Embodiment 2: Reference Figures 1-8 Detailed description of this embodiment, a design method of an aircraft flap based on a fin, for designing the aircraft flap based on the fin of embodiment 1, specifically comprising the following steps:

[0052] S1. Determine the chordwise installation length and installation position of the fin according to the chord length of the trailing edge outboard flap end surface airfoil;

[0053] S2. Determine the maximum spanwise length of the flap trailing edge fin and the maximum spanwise length of the flap leading edge fin according to the thickness of the trailing edge outboard flap end surface airfoil, and complete the fin-based flap design.

[0054] Further, in S1, the chordwise distance between the airfoil leading edge point and the starting installation position of the fin is expressed as:

[0055] ;

[0056] wherein, is the chord length of the trailing edge outboard flap end surface airfoil;

[0057] The chordwise distance between the airfoil trailing edge point and the ending installation position of the fin is expressed as:

[0058] ;

[0059] The chordwise installation length of the fin is expressed as:

[0060] .

[0061] Further, in S2, the maximum spanwise length of the flap trailing edge fin is expressed as:

[0062] ;

[0063] wherein, is the maximum thickness of the trailing edge outboard flap end surface airfoil;

[0064] The maximum spanwise length of the flap leading edge fin is expressed as:

[0065] .

[0066] Specifically, through numerical simulation verification, the installation position of the fin 14 is 0.1 c times the baseline value of the chord length of the airfoil, which can ensure that the aircraft flap has good aerodynamic performance and reliable structure;

[0067] Through numerical simulation verification, when the fin 14 span length and the maximum thickness of the flap end surface airfoil are in the same order of magnitude, the fin structure 13 can have the flap side edge noise suppression effect while having good aerodynamic performance.

[0068] While the application has been described in accordance with the various embodiments shown and described, it is to be understood that the application is not limited to those precise embodiments, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the present application. Furthermore, the language used in this specification has been principally selected for readability and instructional purposes and can not have been selected to delineate or circumscribe the patent rights to which it refers. Accordingly, the present application is intended to be illustrative, but not limiting, of the scope of the application, which is set forth with particularity in the claims that follow.

Claims

1. A fin-based aircraft flap, characterized by, The wing includes a main wing (7), an inboard trailing edge flap (8), an outboard trailing edge flap (9) and a fin structure (13); The inboard trailing edge flap (8) and the outboard trailing edge flap (9) are connected to the main wing (7), and the fin structure (13) is arranged in a cavity structure at a side edge of the outboard trailing edge flap (9), so that the side edge of the flap forms a fin-shaped ventilation structure; The fin structure (13) is composed of a group of densely arranged fins (14), each layer of fins (14) is arranged in an up-and-down staggered manner, and is arranged in three dimensions, and extends inward along the spanwise direction from the side edge of the outboard trailing edge flap (9); The outer contour surface curvature of the fin structure (13) is consistent with the original flap surface curvature, and the spanwise length of the fin (14) is linearly distributed; The wing also includes a fin-based aircraft flap design method, and the specific steps are as follows: S1. According to the chord length of the outboard trailing edge flap end surface airfoil, the chordwise installation length and installation position of the fin are determined; S2. According to the thickness of the outboard trailing edge flap end surface airfoil, the maximum spanwise length of the trailing edge fin and the maximum spanwise length of the leading edge fin are determined, and the fin-based flap design is completed. The maximum spanwise length of the flap trailing edge fin in S2 is represented as: ； wherein tmax is the maximum thickness of the outboard trailing edge flap end plane airfoil; Maximum spanwise length of flap leading edge fin is represented as: 。 2. A fin-based aircraft flap according to claim 1, wherein, In the S1, the chordal distance of the airfoil leading edge point from the fin starting mounting position is represented as: ； wherein Cp is the chord length of the outboard trailing edge flap end plane airfoil; Chordwise distance of the trailing edge point of the airfoil from the fin termination mounting location is represented as: ； Chordwise mounting length of fin is represented as: 。

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