Low-noise undercarriage structure

Abstract

The invention relates to the technical field of noise control, and particularly discloses a low-noise undercarriage structure which comprises an undercarriage main body and a noise reduction acoustic surface, and the noise reduction acoustic surface coats at least part of sound source components on the undercarriage main body in an attached manner so as to realize the noise reduction function of the undercarriage; the noise reduction acoustic surface is of a multi-layer flexible composite structure and comprises an inner side attaching layer, a middle functional layer and an outer side auxiliary layer which are sequentially stacked. The noise reduction acoustic surface is installed on the outer surface of the sound source component of the undercarriage body in an attached mode, on one hand, non-steady flow such as vortex shedding and flow separation of the structure is restrained, on the other hand, non-steady loads generated by interaction of the wake of the upstream component and the downstream component are weakened, and then noise is effectively restrained; the structure of the undercarriage body does not need to be changed, the weight is light, and replacement is convenient.

Description

Technical Field

[0001] This invention relates to the field of noise control technology, and more specifically to a low-noise landing gear structure. Background Technology

[0002] External noise during the takeoff and landing phases of civil aircraft is a significant factor affecting their airworthiness certification. Among these, noise from the airframe configuration, including landing gear and lift-enhancing devices, is a major source of external noise. The landing gear structure is complex, resulting in complex flow phenomena during flight, and a wide variety of noise-generating sub-components, including tires, main struts, side struts, doors, the fuselage, and small to medium-sized accessories (such as lamp covers, torsion bars, tow bars, and pipelines).

[0003] Currently, the primary technical means for landing gear noise control is the fairing, while other noise reduction methods such as tire cavity filling, installing speed brakes, adding spoilers, and plasma excitation have also received attention. Overall, current noise reduction designs have achieved certain noise reduction effects, especially the fairing. However, these designs also have some shortcomings, mainly including increased weight, additional aerodynamic drag, and issues related to structural installation reliability. Furthermore, they may not significantly suppress overall noise in real-world conditions, and may be limited by space constraints and structural movement, making it difficult to achieve sufficient noise reduction. Summary of the Invention

[0004] The purpose of this invention is to provide a low-noise landing gear structure to address the aforementioned problems in landing gear noise control. This solution is achieved by applying a thin, lightweight composite noise-reducing surface to the sound source components on the landing gear body. This does not alter the structure of the landing gear body and is lightweight, easy to install, and easy to replace.

[0005] This invention is achieved through the following technical solution: This invention provides a low-noise landing gear structure, including a landing gear body and a noise-reducing surface. The noise-reducing surface achieves noise reduction by covering at least a portion of the sound source components on the landing gear body. The noise-reducing surface is a multi-layer flexible composite structure, including an inner bonding layer, a middle functional layer, and an outer auxiliary layer stacked sequentially. The inner bonding layer is used to bond with the outer surface of the sound source components on the landing gear body. The middle functional layer is made of felt or fleece material and is used to suppress the interaction between the landing gear body and the external airflow. The outer auxiliary layer is used to protect the material of the middle functional layer.

[0006] As a feasible solution of the present invention, the sound source components include, but are not limited to, one or more of the following on the landing gear body: tire cavity / hub, axle, main strut, diagonal brace, lamp cover, steering rod, torsion bar, and arc disc.

[0007] As a feasible solution of the present invention, the noise reduction surface is installed on the sound source component of the landing gear body by means of binding or bonding.

[0008] As a feasible solution of the present invention, the inner bonding layer is an adhesive layer, which is coated on the surface of the middle functional layer away from the outer auxiliary layer, and is used to achieve the bonding and installation of the noise reduction surface and the sound source components on the landing gear body.

[0009] As a feasible solution of the present invention, the inner bonding layer is an anti-slip layer, which is composed of a solidified rough surface rubber thin layer formed by spraying on the surface of the middle functional layer away from the outer auxiliary layer, so as to increase the friction between the noise reduction surface and the surface of the sound source component on the landing gear body.

[0010] As a feasible embodiment of the present invention, the outer auxiliary layer is a fabric layer made of a rough and tough composite material, and the outer auxiliary layer has a fiber rope net, which is connected and combined with the fabric layer.

[0011] As a feasible solution of the present invention, the intermediate functional layer includes a plurality of functional layer unit blocks arranged in the same direction, with a separation seam formed between adjacent functional layer unit blocks, each functional layer unit block being connected to an outer auxiliary layer, and the outer auxiliary layer being a complete layer with good elasticity.

[0012] As a feasible solution of the present invention, each functional layer unit block is connected to the outer auxiliary layer in a linear manner or at several points by stitching along the center line.

[0013] As a feasible solution of the present invention, the intermediate functional layer includes a support unit and a buffer unit. The support unit has multiple slots along the same direction, and the buffer unit has multiple slots that are respectively filled in the slots of the support unit.

[0014] As a feasible solution of the present invention, the inner bonding layer is removed at the position corresponding to each of the buffer units.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention achieves landing gear noise reduction by flexibly installing lightweight, flexible composite material noise-reducing surfaces on the main landing gear structure. By installing these surfaces, unsteady flows such as vortex shedding and flow separation within the structure are suppressed, and unsteady loads from the interaction between upstream and downstream components are reduced, thus effectively suppressing noise. This invention does not alter or damage the main landing gear structure and can directly achieve noise reduction configurations for existing aircraft landing gear structures through targeted acoustic surface noise reduction design and installation, offering outstanding lightweight, convenience, and practicality. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 The diagram shows a low-noise landing gear structure with noise-reducing surface design in this invention (left) and a corresponding combination of noise-reducing surfaces (right). Figure 2 The diagram shows the low-noise landing gear structure with locally simplified noise-reducing surface design in this invention (top left), the corresponding noise-reducing surface combination diagram (top right), and the exploded assembly view (bottom). Figure 3 This is a schematic diagram of the noise reduction surface basic structure I in this invention; Figure 4 This is a schematic diagram of the noise reduction surface basic structure II in this invention; Figure 5 This is a test scenario and noise reduction effect comparison diagram of the low-noise landing gear structure with noise reduction surface design in this invention. Figure 6 This is a schematic diagram of a low-noise take-off and landing architecture with acoustic surface treatment in some key areas of the present invention; Figure 7 This is a schematic diagram of the noise reduction surface design configuration for moving parts in this invention. Figure 8 This is a schematic diagram of the acoustic surface design configuration with a composite intermediate functional layer in this invention.

[0017] The attached diagram shows the markings and corresponding component names: 1-Inner bonding layer, 2-Middle functional layer, 21-Functional layer unit block, 22-Support unit, 23-Buffer unit, 3-Outer auxiliary layer, 4-Fiber rope net, A-Landing gear body, B-Noise reduction surface. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0020] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0023] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0024] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.

[0025] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to 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 the embodiments of this application.

[0026] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0027] Please refer to Figures 1 to 8 This application provides a low-noise landing gear structure, including a landing gear body A and a noise-reducing surface B. The noise-reducing surface B is fitted onto at least a portion of the outer surface of the sound source components on the landing gear body A to achieve noise reduction. The noise-reducing surface B is a multi-layer flexible composite structure, including an inner bonding layer 1, a middle functional layer 2, and an outer auxiliary layer 3 stacked sequentially. The inner bonding layer 1 is used to fit against the outer surface of the sound source components on the landing gear body A. The middle functional layer 2 is made of felt or fleece material and is used to suppress the interaction between the landing gear body A and the external airflow. The outer auxiliary layer 3 is used to protect the material of the middle functional layer.

[0028] The noise-reducing surface B in this application is a multi-layered flexible composite structure, whose basic components include an inner bonding layer 1 (which can be an adhesive layer or an anti-slip layer), a middle functional layer 2 (which can be felt or fleece material), and an outer auxiliary layer 3. The outer auxiliary layer 3 should generally possess characteristics such as softness, thinness, and a rough surface. The layers of this noise-reducing surface should be stably connected. When installed on the outer surface of the sound source components of the landing gear main body, it should be able to provide micro-scale turbulence and buffer unsteady aerodynamic loads. Furthermore, it can be designed differently for different sub-sound source areas; the shape of the noise-reducing surface can be tailored and specifically designed according to the specific structural characteristics of the sub-sound source areas to achieve a good fit.

[0029] The low-noise landing gear configuration in this application, by installing noise-reducing surfaces on some or all of the sound-source components of the landing gear body, can, on the one hand, exert a micro-scale turbulence effect to suppress unsteady flows such as large-scale vortex shedding and flow separation in the structure itself, and reduce the spatiotemporal correlation of unsteady flows. On the other hand, it can buffer unsteady aerodynamic loads, reduce the dynamic pressure caused by the interaction between the unsteady flows caused by the wakes of upstream components and downstream structures and itself, thereby effectively suppressing the aerodynamic noise of the landing gear.

[0030] Regarding this technical solution, the applicant has conducted large-scale wind tunnel testing and verification on a full-size high-fidelity landing gear model for the specific equipment. The results show that the design can achieve significant noise reduction. Comparisons of test photographs and noise curves between the basic configuration and the noise-reduced configuration are shown in the figures. Figure 5 As shown. At the same time, due to its noise reduction components being made of lightweight composite materials, adopting a thin and light design (the total thickness can be 0.5-1cm or even thinner), and its modular and easy-to-disassemble design, it can be flexibly installed and has good engineering practicality.

[0031] According to some embodiments of this application, the sound source components include, but are not limited to, one or more of the following on the landing gear body: tire recesses / hubs, axles, main struts, diagonal braces, lamp covers, steering rods, torsion bars, and arc discs. It should be noted that all components on the landing gear body that generate noise are referred to as sound source components; an exhaustive list is not provided here.

[0032] According to some embodiments of this application, the noise-reducing surface B can be installed on the sound source component of the landing gear body A by strapping or bonding. This installation method facilitates adjustment or replacement of the noise-reducing surface.

[0033] The noise-reducing surface in this application can be effectively installed on the main structure of the landing gear through methods such as bundling and bonding. In addition, through modular and disassembly design for different sound sources, the noise-reducing installation area can be flexibly combined according to the noise reduction requirements and the main sound source. For example, the best effect can usually be achieved by treating all sub-sound source areas, but for some noise reduction index limits, treating only the main sound source is sufficient to meet the requirements.

[0034] like Figure 1 and Figure 2 As shown, the low-noise landing gear structure in this application has advantages such as not changing the main landing gear structure, lightweight and small size of the noise reduction configuration, and flexible installation; and the noise reduction area can be flexibly adjusted through modular and splicing design according to the noise reduction target and the composition of the main sound sources. The low-noise landing gear structure in this application is based on the basic landing gear structure and performs close-fitting noise reduction surface installation on sound source components of different sizes on the landing gear, such as tire cavities / hubs, axles, main struts, diagonal braces, lamp covers, steering rods, and torsion bars.

[0035] like Figure 6 The diagram shows a low-noise landing gear design where only some key areas undergo acoustic surface treatment. The treated areas include tire recesses / hubs, axles, lamp covers, steering rods, and swivel discs. Compared to a fully treated design, it eliminates moving parts and most secondary noise sources (overhead noise), uses fewer noise reduction components, is relatively lighter, requires less installation work, and still achieves good noise reduction results despite only treating the key areas.

[0036] This application achieves landing gear noise reduction by flexibly installing lightweight, flexible composite material noise-reducing surfaces on the main landing gear structure. By installing these noise-reducing surfaces on the landing gear structure, unsteady flows such as vortex shedding and flow separation are suppressed, and unsteady loads from the interaction between upstream and downstream components are reduced, thereby effectively suppressing noise.

[0037] This application does not alter or damage the main structure of the landing gear, and can achieve modular and splicing installation as well as the combination of different noise reduction treatment areas. Furthermore, for landing gear structures already in use on aircraft, noise reduction effects can be achieved directly through targeted acoustic surface noise reduction design and installation, exhibiting outstanding lightweight, convenience, and practicality.

[0038] According to some embodiments of this application, the inner bonding layer 1 is an adhesive layer, which is coated on the surface of the middle functional layer 2 facing away from the outer auxiliary layer 3, and is used to achieve the bonding and installation of the noise reduction surface and the sound source components on the landing gear body.

[0039] According to some embodiments of this application, the inner bonding layer 1 is an anti-slip layer, which may be composed of a solidified rough surface rubber thin layer formed by spraying on the surface of the middle functional layer 2 away from the outer auxiliary layer 3, and is used to increase the friction between the noise reduction surface and the surface of the sound source component on the landing gear body.

[0040] According to some embodiments of this application, the outer auxiliary layer 3 is a fabric layer made of a rough and tough composite material, and the outer auxiliary layer 3 has a fiber rope net 4, which is connected and combined with the fabric layer.

[0041] like Figure 3 , Figure 4 The diagram shows two schematic representations of noise reduction surface configurations. Figure 3 The noise-reducing surface design shown has an inner bonding layer 1 that is an adhesive layer, which mainly achieves the bonding and installation of the noise-reducing surface to the landing gear structure; the middle functional layer 2 can be felt or the like, which mainly suppresses the interaction between the landing gear structure and the external airflow; and the outer auxiliary layer 3 is made of a rough and tough composite material fabric, which mainly protects the material of the middle functional layer 2.

[0042] right Figure 4 The noise-reducing acoustic surface design shown has an inner bonding layer 1 that is an anti-slip layer. It can be composed of a thin layer of rough rubber formed by spraying or other means on the lower surface of the intermediate functional layer 2. It mainly serves to increase the friction between the acoustic surface and the landing gear structure. The intermediate functional layer 2 can still use felt or the like. The outer auxiliary layer 3 can be composed of a fiber rope net 4 and a thin layer of fabric assembled together. In use, the fiber rope net 4 is used to increase the structural strength of the noise-reducing acoustic surface on the one hand, and to bind the acoustic surface on the other hand, so that it is firmly installed on the structural surface.

[0043] According to some embodiments of this application, the intermediate functional layer 2 includes a plurality of functional layer unit blocks 21 arranged in the same direction, with a separation seam formed between adjacent functional layer unit blocks 21, each functional layer unit block 21 being connected to an outer auxiliary layer, and the outer auxiliary layer being a complete layer with good elasticity.

[0044] According to some embodiments of this application, each functional layer unit block 21 is linearly connected to the outer auxiliary layer or connected at several points by stitching along the center line.

[0045] Specifically, such as Figure 7The diagram shows a noise-reducing surface design for moving components. The intermediate functional layer 2 is divided into multiple functional layer unit blocks 21. Each functional layer unit block 21 is assembled with an outer auxiliary layer via linear connections (or point connections) along the centerline. The outer auxiliary layer is a complete layer with good elasticity. Accordingly, when the moving components on the landing gear undergo relative positional shifts, resulting in changes in the total structural area or external shape, this noise-reducing surface can still achieve complete and effective coverage of the corresponding components.

[0046] According to some embodiments of this application, the intermediate functional layer 2 includes a support unit 22 and a buffer unit 23. The support unit 22 has multiple slots along the same direction, and the buffer unit 23 has multiple slots that are respectively filled in the slots on the support unit 22. The support unit 22 and the buffer unit 23 are made of different materials.

[0047] According to some embodiments of this application, the inner bonding layer 1 is removed at positions corresponding to each buffer unit 23.

[0048] Specifically, such as Figure 8 The diagram shows a noise-reducing surface design configuration with a composite intermediate functional layer 2. The intermediate functional layer 2 is composed of at least two materials, dividing it into a support unit 22 and a high-efficiency buffer unit 23. The support unit 22 primarily provides a certain spatial thickness to the noise-reducing surface, preventing it from being compressed under aerodynamic loads and reducing load buffering effectiveness. The high-efficiency buffer unit 23 further suppresses interactions by using a lighter and softer material.

[0049] In addition, considering irregular and complex local spatial configurations such as the landing gear main strut joint area and wheel axle, and taking into account factors such as more complete coverage and easier installation, a body-fitting noise reduction surface can be designed. Furthermore, considering the convenience of installation, some areas can be perforated or overlapped.

[0050] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-noise landing gear structure, characterized in that, The system includes a landing gear body and a noise-reducing surface. The noise-reducing surface achieves noise reduction by covering at least a portion of the sound source components on the landing gear body. The noise-reducing surface is a multi-layer flexible composite structure, including an inner bonding layer, a middle functional layer, and an outer auxiliary layer stacked sequentially. The inner bonding layer is used to bond with the outer surface of the sound source components on the landing gear body. The middle functional layer is made of felt or fleece material and is used to suppress the interaction between the landing gear body and the external airflow. The outer auxiliary layer is used to protect the material of the middle functional layer.

2. The low-noise landing gear structure according to claim 1, characterized in that, The sound source components include, but are not limited to, one or more of the following on the landing gear body: tire recess / hub, axle, main strut, diagonal brace, lamp cover, steering rod, torsion bar, and arc disc.

3. The low-noise landing gear structure according to claim 1, characterized in that, The noise-reducing surface is installed on the sound source component of the landing gear body by means of binding or bonding.

4. The low-noise landing gear structure according to claim 1, characterized in that, The inner bonding layer is an adhesive layer, which is coated on the surface of the middle functional layer away from the outer auxiliary layer, and is used to achieve the bonding and installation of the noise reduction surface with the sound source components on the landing gear body.

5. The low-noise landing gear structure according to claim 1, characterized in that, The inner bonding layer is an anti-slip layer, which is composed of a solidified rough surface rubber layer formed by spraying on the surface of the middle functional layer away from the outer auxiliary layer, in order to increase the friction between the noise reduction surface and the surface of the sound source component on the landing gear body.

6. The low-noise landing gear structure according to claim 1, characterized in that, The outer auxiliary layer is a fabric layer made of a rough and tough composite material, and the outer auxiliary layer has a fiber rope net, which is connected and combined with the fabric layer.

7. The low-noise landing gear structure according to claim 1, characterized in that, The intermediate functional layer includes multiple functional layer unit blocks arranged in the same direction, with a separation seam formed between adjacent functional layer unit blocks. Each functional layer unit block is connected to the outer auxiliary layer, and the outer auxiliary layer is a complete layer with good elasticity.

8. The low-noise landing gear structure according to claim 7, characterized in that, Each functional layer unit block is connected to the outer auxiliary layer in a linear manner or at several points along the centerline.

9. The low-noise landing gear structure according to claim 1, characterized in that, The intermediate functional layer includes a support unit and a buffer unit. The support unit has multiple slots along the same direction, and the buffer unit has multiple slots that are respectively filled in the slots of the support unit.

10. The low-noise landing gear structure according to claim 9, characterized in that, The inner bonding layer is removed at positions corresponding to each of the buffer units.

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