Micro-grid device for inhibiting aerodynamic noise induced by acoustic liner material framework and application of micro-grid device

Abstract

The invention relates to the technical field of noise reduction, in particular to a micro-grid device for inhibiting aerodynamic noise induced by an acoustic liner material framework and application of the micro-grid device. The micro-grid device provided by the invention comprises a cylinder, an acoustic liner material layer fixed on the surface of the cylinder and a plurality of micro-grid structures fixed in the acoustic liner material layer, the plurality of micro-grid structures are arranged at intervals along the circumferential direction and the axial direction of the cylinder; the mesh size of the micro-grid structure ranges from 0.005 mm to 0.1 mm; the micro-grid structure is made of stainless steel, titanium alloy or high polymer material; the high polymer material is one or more of polytetrafluoroethylene, polyimide and polyethylene. According to the invention, through combination of the acoustic liner material and the micro-grid structure, full-band suppression of low and medium frequency and high frequency noise can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of noise reduction, and in particular to a microgrid device for suppressing aerodynamic noise induced by a sound lining material skeleton and application thereof. Background Art

[0002] Cylindrical structures are widely used in aerospace, automotive engineering, wind power generation, construction equipment and other high-speed fluid dynamics environments. However, when a cylinder is exposed to high-speed airflow, it will produce complex aerodynamic noise problems. When the airflow flows around the cylinder, it will produce obvious vortex streets, which alternate with the airflow and lead to the formation of noise. This aerodynamic noise has a negative impact on the surrounding environment, equipment performance, operator comfort, etc. Therefore, how to effectively reduce the aerodynamic noise generated by the cylindrical structure has become an engineering problem that needs to be solved urgently.

[0003] At present, in order to reduce the aerodynamic noise of a cylinder, the method of coating the surface of the cylinder with a sound lining material is usually adopted. The sound lining material is a porous or composite sound-absorbing material. Its working principle is to absorb the sound energy in the aerodynamic noise and convert the sound energy into heat energy, thereby reducing the propagation of noise. Common sound lining materials include foam materials, glass fibers, ceramic fibers and metal meshes, etc. These materials can usually effectively reduce noise in the low-frequency range.

[0004] Although traditional sound lining materials can reduce aerodynamic noise to a certain extent, especially low-frequency noise, they are limited in their effectiveness in dealing with high-frequency noise and may generate additional high-frequency noise. The structural characteristics of the sound lining material (such as pore size, material density, etc.) determine its ability to absorb noise of different frequencies. Generally speaking, sound lining materials are more suitable for absorbing low-frequency noise with longer wavelengths, but have poor sound absorption effects on high-frequency noise with shorter wavelengths. In addition, since the sound lining materials are exposed to the airflow, they themselves may vibrate and rub against the high-speed airflow, thereby generating additional high-frequency noise, which further exacerbates the aerodynamic noise problem.

[0005] The generation of high-frequency noise is closely related to the aerodynamic characteristics of the cylinder and the surface characteristics of the sound lining material. When the airflow passes through the sound lining material coated on the surface of the cylinder, the velocity gradient of the local airflow increases, and turbulent areas are easily formed. Especially in the process of interaction between the sound lining material and the airflow, these turbulences will excite high-frequency noise. High-frequency noise has a shorter wavelength, slower propagation attenuation, and stronger penetration, and has a more significant impact on the surrounding environment and equipment. Therefore, how to effectively reduce the high-frequency noise caused by the sound lining material has become an important problem in noise reduction technology. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a microgrid device for suppressing aerodynamic noise induced by the skeleton of a sound lining material and its application. The microgrid device provided by the present invention can effectively suppress high-frequency noise.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a microgrid device for suppressing aerodynamic noise induced by a sound lining material skeleton, comprising a cylinder, a sound lining material layer fixed on the surface of the cylinder, and a plurality of microgrid structures fixed inside the sound lining material layer;

[0009] The plurality of microgrid structures are arranged at intervals along the circumferential direction and the axial direction of the cylinder;

[0010] The mesh size of the micro-mesh structure is 0.005-0.1 mm; the material of the micro-mesh structure is stainless steel, titanium alloy or polymer material; the polymer material is one or more of polytetrafluoroethylene, polyimide and polyethylene.

[0011] Preferably, the cylinder is made of aluminum alloy, steel or a composite material of aluminum alloy and steel; and the diameter of the cylinder is 10 to 1000 mm.

[0012] Preferably, the circumferential spacing angle between every two of the microgrid structures is 10° to 60°.

[0013] Preferably, the material of the sound lining material layer includes porous foam, glass fiber felt, ceramic fiber or composite sound absorbing material; the composite sound absorbing material is obtained by compounding at least two of porous foam, glass fiber felt and ceramic fiber.

[0014] Preferably, the thickness of the sound lining material layer is calculated by formula I;

[0015]

[0016] In formula I, t is the thickness of the sound lining material layer; K t is the adjustment factor, K t The value range of is 0.01~0.1, which is determined according to different sound lining materials and absorption frequencies; c is the speed of sound;

[0017] f h Calculated by formula II;

[0018]

[0019] In formula II, St is the Strouhal number, which is 0.2; D is the diameter of the cylinder; U ∞ is the incoming flow velocity.

[0020] Preferably, the porosity of the microgrid structure ranges from 20% to 70%.

[0021] Preferably, the sound lining material layer is fixed to the outside of the cylinder by a mechanical fastener or by adhesive bonding.

[0022] Preferably, the microgrid structure is fixed inside the sound lining material by means of mechanical fixings, adhesive bonding, hot melting or welding; the mechanical fixings include mechanical buckles or mechanical clamps.

[0023] The present invention also provides the application of the microgrid device described in the above technical solution in the aircraft landing gear support structure of an aerospace vehicle, an automobile exhaust pipe and a building exhaust equipment.

[0024] The present invention provides a microgrid device for suppressing aerodynamic noise induced by a sound lining material skeleton, comprising a cylinder, a sound lining material layer fixed on the surface of the cylinder, and a plurality of microgrid structures fixed inside the sound lining material layer; the plurality of microgrid structures are arranged at intervals along the circumference and axial direction of the cylinder; the mesh size of the microgrid structure is 0.005-0.1 mm; the material of the microgrid structure is stainless steel, titanium alloy or polymer material; the polymer material is one or more of polytetrafluoroethylene, polyimide and polyethylene. The technical advantages of the present invention are: (1) the present invention adds a microgrid layer with porosity and high ventilation performance to the sound lining material skeleton structure, so that it interferes with the airflow, reduces the turbulence and small-scale vortex structure generated by the airflow disturbing the sound lining material skeleton, and thus reduces the high-frequency noise component. In addition, the sound lining material is a porous sound-absorbing material with good low-frequency and medium-frequency noise absorption performance. In summary, the present invention can achieve full-band suppression of medium-low-frequency and high-frequency noise by combining the sound lining material and the microgrid structure. (2) The arrangement of the microgrid structure of the present invention is flexible and can be adjusted according to the shape of different cylinders and the application environment. It has a simple structure and is easy to install. The overall noise reduction performance can be flexibly adjusted by changing the thickness, material and mesh size of the microgrid structure. (3) The material of the microgrid structure provided by the present invention has the advantages of low cost, light structure, wide adaptability, significant noise reduction effect, and simple design and manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the acoustic liner microgrid technology used for noise control of cylinders;

[0026] Figure 2 Schematic diagrams defining the main characterization parameters for acoustic lining and microgrid layout;

[0027] Figure 3 Schematic diagram for defining the main characterization parameters of microgrid layout. DETAILED DESCRIPTION

[0028] like Figure 1 As shown, the present invention provides a microgrid device for suppressing aerodynamic noise induced by a sound lining material skeleton, comprising a cylinder, a sound lining material layer fixed on the surface of the cylinder, and a plurality of microgrid structures fixed inside the sound lining material layer;

[0029] The plurality of microgrid structures are arranged at intervals along the circumferential direction and the axial direction of the cylinder;

[0030] The mesh size of the micro-mesh structure is 0.005-0.1 mm; the material of the micro-mesh structure is stainless steel, titanium alloy or polymer material; the polymer material is one or more of polytetrafluoroethylene, polyimide and polyethylene.

[0031] As an embodiment, the material of the cylinder is aluminum alloy, steel or a composite material of aluminum alloy and steel. As an embodiment, the diameter of the cylinder is 10 to 1000 mm. In a specific embodiment, the diameter of the cylinder can be 20 mm. As an embodiment, the cylinder is a hollow pipe or a solid cylinder, which is suitable for scenes where noise reduction is required, such as landing gear cylindrical parts and aircraft protrusions.

[0032] As an embodiment, the material of the sound lining material layer includes porous foam, glass fiber felt, ceramic fiber or composite sound absorbing material; the composite sound absorbing material is composited from at least two of porous foam, glass fiber felt and ceramic fiber.

[0033] In the present invention, the material of the sound lining material layer has good sound absorption performance and is suitable for low-frequency noise suppression.

[0034] As an implementation mode, the circumferential spacing angle of each two microgrid structures is 10° to 60°. In a specific embodiment, the circumferential spacing angle of each two microgrid structures can be 45°. In the present invention, the spacing arrangement of the microgrid structures can be optimized according to the shape of the cylinder and the airflow direction, and the spacing distance between the microgrid layers can be designed according to the noise characteristics to ensure uniform distribution of the airflow and effective attenuation of the noise.

[0035] In the present invention, the above fixing method can ensure the structural stability and long-term noise reduction performance of the microgrid structure in high-speed airflow.

[0036] As an implementation method, the thickness of the sound lining material layer is 5 to 50 mm. In a specific embodiment, since the thickness of the cylinder is 20 mm, the dominant frequency is

[0037]

[0038] According to the dominant noise frequency, the thickness of the acoustic lining t can be estimated by the empirical formula

[0039]

[0040] Take K t =0.02, substitute into the above formula

[0041]

[0042] The thickness of the sound lining material layer can be 7 mm. In the present invention, the thickness of the sound lining material can be adjusted according to the frequency range and intensity of the airflow noise to achieve effective absorption of medium and low frequency noise.

[0043] As an implementation mode, the sound lining material layer is fixed to the outside of the cylinder by a mechanical fastener or by adhesive bonding.

[0044] As an embodiment, the material of the micromesh structure is stainless steel, titanium alloy or polymer material; the polymer material is one or more of polytetrafluoroethylene, polyimide and polyethylene. In the present invention, the material of the micromesh structure has high air permeability, corrosion resistance and good mechanical strength, and is suitable for long-term use in airflow environment.

[0045] As an implementation mode, the mesh size (side length of the mesh) of the micro-mesh structure is 0.005-0.1 mm. In a specific embodiment, the mesh size of the micro-mesh structure can be 0.05 mm. In the present invention, the mesh size of the micro-mesh structure can be selected according to the target noise frequency. Smaller meshes (such as 0.005-0.02 mm) are suitable for absorbing high-frequency airflow noise (greater than 2000 Hz), while larger meshes (such as 0.05-0.1 mm) can be used to process medium and low frequency noise (500 Hz-2000 Hz).

[0046] As an implementation mode, the porosity of the micro-grid structure is 20-70%. In a specific embodiment, the porosity of the micro-grid structure can be 60%. In the present invention, by optimizing the porosity and mesh density, the micro-grid structure can reduce the turbulence and eddy flow when the airflow passes through, and is particularly suitable for suppressing high-frequency noise generated by high-speed airflow.

[0047] As an implementation mode, the microgrid structure is fixed inside the sound lining material by means of mechanical fixings, adhesive bonding, hot melting or welding; the mechanical fixings include mechanical clips or mechanical clamps.

[0048] In the present invention, the sound lining material and the microgrid structure are combined to form a multi-layer composite noise reduction structure, which can simultaneously suppress noise in different frequency bands, wherein the sound lining material mainly absorbs medium and low frequency noise, while the microgrid structure mainly suppresses high frequency noise.

[0049] The present invention also provides a method for preparing a microgrid device for suppressing aerodynamic noise induced by a sound lining material skeleton, comprising the following steps:

[0050] (1) Clean the surface of the cylinder until it is free of dust and oil;

[0051] (2) After the sound lining material is fixed on the surface of the cylinder, the edge of the sound lining material is smoothed;

[0052] (3) Fixing the micro-grid structure inside the sound lining material.

[0053] As an implementation, the sound lining material can be fixed by adhesive or mechanical fixing. As an implementation, the mechanical fixing includes a clamp.

[0054] In the present invention, the purpose of smoothing the edge of the sound lining material is to prevent the airflow from bypassing the edge of the material and generating unnecessary noise.

[0055] In the present invention, the micro-grid structures should be evenly distributed inside the sound lining material to ensure that there is no significant gap between the micro-grid structures and the sound lining material. The spacing between the micro-grid structures should be kept uniform to achieve the best noise suppression effect.

[0056] In the present invention, after the microgrid structure is fixed, the entire device is also inspected to ensure that all components are firmly installed and there are no obvious defects or gaps.

[0057] The present invention also provides the application of the microgrid device described in the above technical solution in the aircraft landing gear support structure of an aerospace vehicle, an automobile exhaust pipe and a building exhaust equipment.

[0058] In the present invention, the device can significantly reduce high-frequency noise components above 10kHz in the above-mentioned fields, improve the noise suppression effect, and improve the operating environment of the equipment.

[0059] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0060] Example 1

[0061] This embodiment is a device applied to a cylinder (landing gear support component, with a diameter of 20 mm), which uses an acoustic lining material and a micro-mesh structure to reduce aerodynamic noise.

[0062] The preparation process is:

[0063] First, select the sound lining material (specifically, polyurethane foam, the sound absorption coefficient of this material can reach 0.8-0.95 at a frequency of 500Hz). Since the thickness of the cylinder is 20mm, the dominant frequency is

[0064]

[0065] According to the dominant noise frequency, the thickness of the acoustic lining t can be estimated by the empirical formula

[0066]

[0067] Take K t =0.02, substitute into the above formula

[0068]

[0069] The thickness of the sound lining material layer may be 7 mm. After the sound lining material is fixed on the surface of the cylinder by means of an adhesive (specifically a polyurethane adhesive), the edge of the sound lining material is flattened.

[0070] Finally, the microgrid structure is fixed inside the sound lining material by bonding and pasting the microgrid on the inner surface of the sound lining. Specifically, the microgrid structure is distributed at equal angles along the circumference and axial direction of the cylinder.

[0071] The characterization parameters of the acoustic lining material and microgrid arrangement are as follows: Figure 2 As shown in the figure, the thickness of the acoustic liner is represented by t, the thickness of the microgrid is represented by d, and the angle is represented by θ. In addition, the porosity of the microgrid is represented by σ, as shown in the figure. Figure 3 Specifically, the data of t, d, θ and σ are 7 mm, 1 mm, 45° and 60% respectively.

[0072] Performance Testing:

[0073] (1) Noise test: The noise spectra of an unwrapped cylinder, a cylinder wrapped with an acoustic liner, and a cylinder wrapped with an acoustic liner with an embedded microgrid are compared through wind tunnel tests, with a focus on the noise in the high-frequency range above 500 Hz (the dominant frequency of the cylinder) and 2000 Hz (the additional high-frequency noise generated by the acoustic liner).

[0074] (2) Aerodynamic performance test: The aerodynamic drag of a cylinder wrapped with an acoustic liner and a micro-mesh structure was tested through a wind tunnel experiment. The results showed that the increase in aerodynamic drag was kept within 10% compared with the unwrapped cylinder.

[0075] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A microgrid device for suppressing aerodynamic noise induced by a sound lining material skeleton, characterized in that: It includes a cylinder, a sound lining material layer fixed on the surface of the cylinder, and a plurality of micro-grid structures fixed inside the sound lining material layer; The plurality of microgrid structures are arranged at intervals along the circumferential direction and the axial direction of the cylinder; The mesh size of the micro-mesh structure is 0.005-0.1 mm; the material of the micro-mesh structure is stainless steel, titanium alloy or polymer material; the polymer material is one or more of polytetrafluoroethylene, polyimide and polyethylene.

2. The microgrid device according to claim 1, characterized in that: The material of the cylinder is aluminum alloy, steel or a composite material of aluminum alloy and steel; the diameter of the cylinder is 10 to 1000 mm.

3. The microgrid device according to claim 1 or 2, characterized in that: The circumferential spacing angle between every two microgrid structures is 10° to 60°.

4. The microgrid device according to claim 1, characterized in that: The material of the sound lining material layer includes porous foam, glass fiber felt, ceramic fiber or composite sound absorbing material; the composite sound absorbing material is obtained by compounding at least two of the porous foam, glass fiber felt and ceramic fiber.

5. The microgrid device according to claim 1, characterized in that: The thickness of the sound lining material layer is calculated by formula I; In formula I, t is the thickness of the sound lining material layer; K t is the adjustment factor, K t The value range of is 0.01~0.1, which is determined according to different sound lining materials and absorption frequencies; c is the speed of sound; f h Calculated by formula II; In formula II, St is the Strouhal number, which is 0.2; D is the diameter of the cylinder; U ∞ is the incoming flow velocity.

6. The microgrid device according to claim 1, characterized in that: The porosity of the micro-grid structure ranges from 20% to 70%.

7. The microgrid device according to claim 1, characterized in that: The sound lining material layer is fixed to the outside of the cylinder by a mechanical fixing member or by an adhesive.

8. The microgrid device according to claim 1, characterized in that: The microgrid structure is fixed inside the sound lining material by means of mechanical fixings, adhesive bonding, hot melting or welding; the mechanical fixings include mechanical buckles or mechanical clamps.

9. Use of the microgrid device according to any one of claims 1 to 8 in aircraft landing gear support structures of aerospace vehicles, automobile exhaust pipes and building exhaust equipment.

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