Full-frequency-domain strong sound insulation and noise reduction silicon dioxide aerogel felt assembly for rotorcraft and preparation method and application of silicon dioxide aerogel felt assembly

Abstract

The invention discloses a full-frequency-domain strong sound insulation and noise reduction silicon dioxide aerogel felt assembly for a rotorcraft and a preparation method and application of the full-frequency-domain strong sound insulation and noise reduction silicon dioxide aerogel felt assembly. The assembly comprises a nano-porous aerogel plate serving as a first layer of sound insulation barrier, a porous sound absorption material plate serving as a middle sound absorption and noise reduction layer and a hard foam material plate serving as a third layer of sound insulation barrier which are sequentially stacked. The three-layer structure is bonded through an adhesive to form an integrated composite structure, the total thickness is smaller than or equal to 50 mm, the surface density is smaller than or equal to 2 kg / m, and a noise reduction structure with acoustic impedance changing in a gradient mode is formed. By means of the mode, full-frequency-domain efficient sound insulation and noise reduction are achieved through the three-layer gradient impedance structure, meanwhile, the requirements for light weight and high strength are met, the excellent heat insulation and hydrophobic characteristics are achieved, the composite material can be widely applied to noise reduction and thermal protection in a rotorcraft cabin, the comfort level of pilots and passengers is remarkably improved, and hearing damage is prevented.

Description

Technical Field

[0001] This invention relates to the field of sound insulation and noise reduction materials, and in particular to a full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft, its preparation method and application. Background Technology

[0002] The internal sound insulation and noise reduction engineering of transportation vehicles such as rotorcraft, helicopters, flying cars, seaplanes, and aircraft using turbofan engines is a complex and difficult project. At present, there is still a lack of ideal sound insulation materials that can effectively solve the impact of internal noise on the physical and mental health of flight crews and passengers.

[0003] Taking helicopters as an example, the cabin noise intensity is affected by multiple factors, including differences in aircraft type, flight status, cabin location, and existing noise reduction measures. A comprehensive analysis of existing research data shows that: Untreated helicopter cockpit noise levels range from 102.5 to 111.1 dB, equivalent to the noise levels of heavy machinery such as chainsaws (approximately 110 dB) or tractors (approximately 105 dB). It is noteworthy that noise levels fluctuate significantly under different flight conditions, particularly during hovering, climbing, or maneuvering, where noise levels may reach peak levels. Even with a professional noise-reducing helmet conforming to the GJB1564A-2012 military standard, pilots may still be exposed to noise levels exceeding 100 dB.

[0004] In-depth analysis of the spectral characteristics of helicopter cabin noise revealed that it is primarily dominated by low-frequency noise below 500Hz. This noise originates from the superposition effect of multiple sources of noise, including rotor vortices, engine mechanical vibrations, and aerodynamic turbulence, ultimately forming a broadband sound field covering 20-3000Hz. Of particular note is the extremely strong penetrating power of low-frequency sound waves, which limits the sound attenuation effect of conventional sound insulation materials.

[0005] Taking flying cars as an example, the noise they generate during operation has multi-source characteristics, mainly including the following key noise sources: Motor noise: Although electric motor systems have a significant advantage in quietness compared to traditional internal combustion engines, electromagnetic vibration and mechanical transmission will still generate medium- to high-frequency noise under high power output conditions; Rotor noise: As the main source of noise, the rotor generates high-bandwidth noise during takeoff and landing due to tip vortices and dynamic stall effects. Its sound pressure level increases exponentially with the increase of rotational speed. Airflow noise: During flight, the interaction between airflow and the vehicle body and rotor excites boundary layer turbulence, generating low- to mid-frequency noise.

[0006] The challenges encountered by the aforementioned helicopters in the noise reduction process are as follows: The engine's native noise level can reach 140-160dB, and the sound insulation of the fuselage needs to balance weight, fuel efficiency and acoustic performance. International requirements: The International Civil Aviation Organization (ICAO) stipulates that the cabin noise of civil aircraft must be below 85 dB, but helicopters generally exceed the standard by 10-25 dB due to their special configuration; Domestic progress: The "MHT6128-2024 Aircraft Noise Measurement and Assessment" implemented in 2024 has strengthened noise control and data collection requirements, incorporated helicopter dynamic noise testing into the mandatory standard, and required that the noise data collection accuracy reach ±1dB throughout the entire flight phase.

[0007] Currently, helicopter noise levels are generally in the high-intensity range of 90-110 dB, far exceeding civil aviation noise standards (<85 dB). Furthermore, its low-frequency characteristics can exacerbate human discomfort. Although active noise reduction technologies (such as adaptive filtering technology) have entered the research and development stage, current methods primarily rely on physical sound insulation and protective equipment to mitigate the impact of noise.

[0008] Prolonged exposure to this type of noise environment can significantly harm the health and experience of pilots and crew members. Mild exposure can lead to increased fatigue, decreased concentration, and sluggish thinking and responsiveness, potentially causing unclear command transmission. More severe exposure can result in endocrine disorders, tinnitus, hearing loss or even deafness, and accelerated heart rhythm disturbances. For military helicopters, these effects can directly weaken the crew's combat effectiveness, thus negatively impacting combat capability. Summary of the Invention

[0009] The main technical problem solved by this invention is to provide a full-frequency domain strong sound insulation and noise reduction silica aerogel felt component for rotorcraft, its preparation method and application. It achieves efficient sound insulation and noise reduction in the full frequency domain through a three-layer gradient impedance structure, while meeting the requirements of lightweight and high strength. It also has excellent heat insulation and water-repellent properties, and can be widely used in noise reduction and thermal protection in rotorcraft cabins, significantly improving the comfort of pilots and passengers and preventing hearing damage.

[0010] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: to provide a full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft, comprising: a nanoporous aerogel board as the first sound insulation barrier, a porous sound-absorbing material board as the middle sound absorption and noise reduction layer, and a rigid foam material board as the third sound insulation barrier. The three-layer structure is bonded together with adhesive to form an integrated composite structure with a total thickness of ≤50mm and a surface density of ≤2kg / m², and constitutes a noise reduction structure with varying acoustic impedance gradient.

[0011] In a preferred embodiment of the present invention, the nanoporous aerogel plate is any one of silica aerogel felt, alumina aerogel plate, carbon aerogel plate or cellulose aerogel plate.

[0012] In a preferred embodiment of the present invention, the nanoporous aerogel board is a silica aerogel felt board with a density ≤360kg / m³, which is used to isolate thermal radiation.

[0013] In a preferred embodiment of the present invention, the silica aerogel felt board includes a flexible felt material matrix and silica aerogel blocks: silica aerogel blocks with different solid contents are filled and solidified in the fiber gaps of a flexible felt material matrix with different densities, and after aging, hydrophobic modification, and supercritical CO2 drying, lightweight silica aerogel felt boards with different densities are formed.

[0014] In a preferred embodiment of the present invention, the porous sound-absorbing material board is any one of melamine foam material board, sound-absorbing cotton, meltblown glass wool, or meltblown basalt wool.

[0015] In a preferred embodiment of the present invention, the rigid foam material board is any one of rigid PU polyurethane foam board, XPS foam extruded board, PE board, PP board, PEEK board, aluminum foam board or titanium foam board.

[0016] In a preferred embodiment of the present invention, the porous sound-absorbing material board is a melamine foam material board, and the rigid foam material board is a rigid PU polyurethane foam board.

[0017] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is: a method for preparing a full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft, comprising the following steps: S1. Material preparation: Prepare nanoporous aerogel boards, porous sound-absorbing material boards, and rigid foam material boards; S2. Cutting: Cut the three-layer material board according to the predetermined dimensions; S3. Adhesive bonding: Apply adhesive between the nanoporous aerogel board and the porous sound-absorbing material board, and between the porous sound-absorbing material board and the rigid foam material board, and press them together to form a three-layer composite structure. S4. Reinforcement: The three-layer composite structure is fixed by through-riveting with nylon nails; S5. Inspection: Test the thickness, surface density and sound insulation performance of the components to ensure that the sound insulation at 250Hz is ≥20dB, the sound insulation at 500Hz is ≥25dB ​​and the sound insulation at 1000Hz is ≥25dB. S6. Packaging and Delivery: Protectively package and deliver qualified components.

[0018] In a preferred embodiment of the present invention, the adhesive in step S3 is a high-temperature resistant epoxy resin adhesive or a polyurethane structural adhesive, the coating thickness of the adhesive is 0.1-0.36 mm, the curing temperature is ≤80℃, and the curing time is 20-40 min; the distribution density of the nylon nails in step S4 is 4-6 per square meter.

[0019] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is to provide an application of a full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft, which can be used for the treatment of sound insulation and noise reduction and heat insulation engineering in the interior of rotorcraft, flying cars, seaplanes, and turbofan engines.

[0020] The beneficial effects of this invention are: Full-frequency domain high-efficiency noise reduction: Through the acoustic impedance gradient design of three-layer materials, full-frequency domain sound insulation is achieved, and the cabin noise can be controlled below 85dB, significantly improving auditory comfort; especially for rotor noise above 2000Hz, the sound insulation reaches 35-40dB, which is better than traditional materials. Lightweight and high strength: The component has a surface density of ≤2kg / m², making it the first inorganic aerogel sound insulation material in China to meet the requirements of aviation lightweighting, while also possessing high mechanical strength; Integrated sound insulation, heat insulation and protection: The silica aerogel layer can not only insulate sound, but also effectively block heat radiation, protect the internal melamine foam and rigid PU from deformation at high temperatures, and maintain the overall shape of the component. Hydrophobicity and weather resistance: The aerogel has a hydrophobicity of ≥98%, does not absorb water or increase in weight during long-term use, adapts to high humidity environments, and ensures that it does not increase in weight during long-term use; Multi-scenario applicability: Applicable to sound and heat insulation engineering treatment in the cabins and engine compartments of rotary-wing aircraft, helicopters, flying cars, seaplanes, turbofan engines, etc. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a schematic diagram of a preferred embodiment of the full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft of the present invention. Figure 2 This is a sound insulation measurement curve of the silica aerogel felt assembly in Embodiment 3 of the present invention; The components in the attached diagram are labeled as follows: 1. Silica aerogel felt board; 2. Melamine foam board; 3. Rigid PU polyurethane foam board. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. Example

[0024] This invention provides a full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft, comprising a nanoporous aerogel board, a porous sound-absorbing material board, and a rigid foam material board, the three layers being stacked sequentially and bonded together with an adhesive to form an integrated composite structure.

[0025] The nanoporous aerogel board, serving as the first layer of sound insulation barrier, can be any one of silica aerogel felt, alumina aerogel board, carbon aerogel board, or cellulose aerogel board.

[0026] The porous sound-absorbing material board, serving as the intermediate sound-absorbing and noise-reducing layer, can be any one of melamine foam material board, sound-absorbing cotton, meltblown glass wool, or meltblown basalt wool.

[0027] The rigid foam material board, serving as the third layer of sound insulation barrier, can be any one of rigid PU polyurethane foam board, XPS foam extruded board, PE board, PP board, PEEK board, aluminum foam board, or titanium foam board.

[0028] The above three-layer structure is integrated into a composite structure with a total thickness controlled to ≤50mm and a surface density controlled to ≤2kg / m², which can ensure both lightweight and sound and heat insulation.

[0029] The three-layer structural materials of the above components have complementary sound insulation and sound absorption properties, forming a noise reduction structure with a gradient change in acoustic impedance. This causes sound waves to be reflected, scattered, and dissipated multiple times when passing through the interfaces of each layer, reducing transmitted energy and forming a noise reduction effect that covers the entire frequency domain.

[0030] After comprehensive noise reduction, the cabin noise can be effectively controlled below 85 dB, meeting the noise control requirements of helicopter cabins. It is suitable for aviation noise reduction application scenarios with strict limitations on weight, thickness and high temperature environment. Example

[0031] This invention provides a full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft.

[0032] In this embodiment, the nanoporous aerogel board is a silica aerogel felt board 1, the porous sound-absorbing material board is a melamine foam material board 2, and the rigid foam material board is a rigid PU polyurethane foam board 3.

[0033] In detail: First, the silica aerogel felt board includes a flexible felt material matrix and silica aerogel blocks. Silica aerogel blocks with different solid contents are filled and solidified in the fiber gaps of the flexible felt material matrix with different densities. After aging, hydrophobic modification, and supercritical CO2 drying, lightweight silica aerogel felt boards with different densities that can isolate heat radiation are formed.

[0034] Furthermore, the flexible felt material matrix is ​​made of low-density flexible felt material. The low-density flexible felt material matrix is ​​impregnated in silica sol, and then heated to allow the low-solids silica sol to gel and solidify in the interfiber gaps of the matrix, forming a wet gel felt. After aging and hydrophobic modification, it is dried with supercritical CO2 to form a soft, rollable, lightweight silica aerogel felt with a density ≤360kg / m³.

[0035] This silica aerogel felt material is soft, flexible, and has good strength. It can adapt to the curved surfaces of the aircraft cabin, has good installation fit, and has no internal stress release. It fits well with the curved surfaces of the aircraft cabin, which is beneficial for the construction and installation of curved surfaces in the aircraft interior. At the same time, the silica aerogel felt material has a high water repellency rate, does not absorb water, and does not increase the weight of the aircraft during long-term use.

[0036] Silica aerogel felt can serve as a high-impedance sound insulation layer. Its dense aerogel structure can form an efficient acoustic impedance barrier, which can reflect high-frequency noise and prevent high-frequency sound waves from penetrating to subsequent structural layers, thus reducing the transmission path of high-frequency noise at the source.

[0037] Using silica aerogel felt for sound insulation and noise reduction in helicopter cabin interiors has a good sound insulation and noise reduction effect, while also blocking heat radiation, achieving the dual functions of sound insulation and heat insulation.

[0038] Secondly, melamine foam material board, as a sound-absorbing transition layer, is suitable for use between aerogel felt board and PU foam. Its open structure can absorb noise, reduce sound wave reflection back to the aerogel layer, and avoid secondary noise interference. At the same time, the material has a certain structural strength and can serve as a supporting medium to ensure the interlayer stability and overall structural rigidity of the entire sound insulation component.

[0039] Furthermore, as a high-rigidity material, rigid PU polyurethane foam board can suppress low-frequency vibration transmission, especially effectively blocking vibration noise generated by equipment such as engines. It can effectively block the transmission of residual low-frequency sound waves into the cabin after the first two layers of treatment, ultimately forming a full-band sound insulation and noise reduction system from high-frequency reflection, mid-frequency absorption to low-frequency blocking.

[0040] The three-layer structure of the above components has complementary sound insulation and sound absorption properties, forming a noise reduction structure with gradient changes in acoustic impedance: high impedance aerogel felt → medium impedance melamine foam → low impedance PU foam, resulting in a noise reduction effect covering the entire frequency domain.

[0041] The silica aerogel felt can both isolate the heat radiation temperature of helicopters and protect melamine foam boards and rigid PU polyurethane foam boards from high temperatures, maintaining their shape.

[0042] The above three-layer structure is integrated into a single composite, with a total thickness of 50mm and a surface density of 2kg / m², achieving both lightweight design and high performance. Its sound insulation performance in the key frequency range is as follows: The sound insulation is ≥20dB in the 250Hz frequency band, ≥25dB ​​in the 500Hz frequency band, and ≥25dB ​​in the 1000Hz frequency band.

[0043] The full-frequency domain strong sound insulation and noise reduction component with silica aerogel felt as the core of this embodiment, when applied to the sound insulation and noise reduction project inside the aircraft, will greatly reduce the harm of noise to helicopter pilots and passengers, ensure the physical and mental health of pilots and passengers and a comfortable flight environment experience, enable flight crew members to carry out work efficiently with good hearing, concentration, clear communication of commands, and quick response, and improve the combat effectiveness of the crew.

[0044] The full-frequency-domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft in this embodiment can be used for sound insulation and noise reduction projects in rotorcraft, flying cars, seaplanes, turbofan engine aircraft, etc.

[0045] After comprehensive noise reduction, the cabin noise can be effectively controlled below 85 dB, meeting the cabin noise control requirements. It is suitable for aviation noise reduction application scenarios with strict limitations on weight, thickness and high temperature environment. Example

[0046] This invention provides a method for preparing a full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft. The assembly uses silica aerogel felt as the first sound barrier, melamine foam as the intermediate sound absorption and noise reduction layer, and rigid PU polyurethane foam as the third sound barrier. The specific preparation steps are as follows: S1. Material preparation: Prepare silica aerogel felt board, melamine foam material board and rigid PU polyurethane foam board.

[0047] S2. Cutting: Cut the silica aerogel felt board, melamine foam board and rigid PU polyurethane foam board according to the predetermined size.

[0048] S3. Applying adhesive and bonding: Apply high-temperature resistant epoxy resin or polyurethane structural adhesive between the silica aerogel felt board and the melamine foam board, with an adhesive thickness of 0.15-0.25 mm. A high-temperature resistant epoxy resin or polyurethane structural adhesive is applied between the melamine foam board and the rigid PU polyurethane foam board, with a coating thickness of 0.20-0.30 mm. The three-layer composite structure is formed by hot pressing and curing at 60-80℃ for 20-40 minutes.

[0049] S4. Mechanical reinforcement: The three-layer composite structure is fixed by through-riveting with nylon nails, with a distribution density of 4-6 nails per square meter. After riveting, silicone rubber sealant can be applied to the nail heads.

[0050] S5. Inspection: Test the thickness, areal density, and sound insulation performance of the components. The total thickness is 50mm, the tolerance is ±1mm, and the surface density is 2.0kg / m². Sound insulation ≥20dB at 250Hz, and ≥25dB ​​at 500Hz and 1000Hz.

[0051] S6. Packaging and Delivery: Protectively package qualified components and deliver them to the customer.

[0052] The three-layer composite structure in Example 3 was used as the test sample for testing.

[0053] I. Test method: The sound insulation characteristics of aerogel felt are determined by standing wave tube test method according to GB / T18696.2-2002.

[0054] II. Testing Standard: Based on GB / T 18696.2-2002 "Measurement of Sound Absorption Coefficient and Acoustic Impedance in Acoustic Impedance Tubes, Part 2: Transfer Function Method", dual-diameter testing is adopted.

[0055] III. Sample Preparation: 1. Prepare samples of two different sizes, with diameters of Φ100mm and Φ30mm respectively; 2. Test frequency range: Φ100mm sample: Test frequency range 50-1600Hz, used for low-frequency sound insulation performance analysis. Φ30mm sample: The test frequency range is 800-6300Hz, covering the mid-to-high frequency range acoustic response characteristic testing.

[0056] Table 1: Sound insulation test data record of silica aerogel felt assembly:

[0057] Analysis of the full-frequency domain sound insulation performance in the table above shows that: 1. Low frequency band (50-250Hz): At 250Hz, the sound insulation of a single-layer silica aerogel felt board is only 5.565dB, the sound insulation of a single-layer melamine foam board is only 1.141dB, and the sound insulation of a rigid PU polyurethane foam board is 18.74dB. The sound insulation of the three-layer composite structure in this frequency band is stable at 25-29dB, proving that the sound insulation effect is significantly improved after the three-layer structure works together.

[0058] 2. Mid-frequency band (315-1000Hz): Single-layer silica aerogel felt boards exhibit a low sound insulation performance (1.73-17.704dB) in the 315-800Hz range, but the overall sound insulation performance can be maintained through the sound absorption compensation of the melamine layer (0.697-2.641dB). The sound insulation of the three-layer composite structure in this frequency band reaches 25.601dB at 500Hz, which fully meets the technical specifications (≥25dB).

[0059] 3. High-frequency band (1250-6300Hz): The silica aerogel felt reached a peak of 30.11 dB at 4000 Hz, demonstrating the high-frequency advantages of the nanoporous structure. Meanwhile, the sound insulation of the three-layer composite structure in this frequency band is significantly improved to 35-47dB.

[0060] 4. Regarding the sound insulation of silica aerogel felt boards: In the low and mid frequencies, the sound insulation of the three-layer composite structure is 25-29dB, which meets the standard. However, at this time, it mainly relies on the low-frequency sound insulation advantage of rigid PU polyurethane foam board. For example, at 500Hz, PU foam contributes 28.444dB. As the frequency increases, the reflective effect of the aerogel felt gradually becomes more prominent (e.g., aerogel contributes 23.167dB at 1000Hz), complementing the PU foam.

[0061] In the high-frequency range, the sound insulation of the three-layer composite structure is significantly improved to 40-47 dB, and exhibits the following characteristics: The sound insulation of a single layer of aerogel felt reaches 29.96dB at 3150Hz, which is close to its peak performance; At this point, the sound insulation of the rigid PU polyurethane foam board actually decreased to 18.708dB, indicating that the high-frequency sound insulation is mainly dominated by aerogel felt.

[0062] Therefore, it can be seen that silica aerogel felt components not only have excellent sound insulation effects in the low and medium frequency range, but also have stronger sound insulation effects in the high frequency range.

[0063] IV. Test Conclusion: The sound insulation at 250Hz is 29.043dB, which is greater than 20dB, meeting the sound insulation performance requirements of the key frequency band. The sound insulation at 500Hz is 25.601dB, which is greater than 25dB and meets the sound insulation performance requirements of the key frequency band. The sound insulation at 1000Hz is 27.626dB, which is greater than 25dB, meeting the sound insulation performance requirements of the key frequency band.

[0064] The beneficial effects of the full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft, its preparation method, and its application are as follows: To address the challenge of cabin noise control in rotorcraft such as helicopters and flying cars, a full-frequency domain strong sound insulation and noise reduction component based on silica aerogel material was developed. By leveraging the complementary sound insulation and absorption properties of three layers of material, a noise reduction structure with gradient acoustic impedance was formed. Verification tests have shown that it achieves excellent sound insulation and noise reduction effects, reducing cabin noise to below 85dB. It significantly improves the auditory comfort and flight environment experience of pilots and passengers, and effectively prevents hearing damage caused by noise. In particular, the silica aerogel felt used not only has sound insulation and noise reduction effects, but also can isolate the heat radiation of helicopters, protect the melamine foam board and rigid PU polyurethane foam board from high temperature, and maintain the overall shape of the components. The overall areal density of this component is controlled to be ≤2kg / m³. 2 It is currently the only lightweight aerogel inorganic material component in China that meets the requirements for aircraft sound insulation and heat insulation engineering applications. This silica aerogel felt assembly not only has excellent sound insulation performance in the low and mid frequency range, but also has stronger sound insulation performance in the high frequency range, meeting the requirements of full-frequency domain strong sound insulation and noise reduction for rotorcraft. The silica aerogel felt material in this silica aerogel felt assembly has a high hydrophobicity and does not absorb water, which can ensure that the material does not increase in weight during long-term use of the aircraft. It can be used for sound insulation and heat insulation engineering in the interior of rotorcraft, flying cars, seaplanes, and turbofan engines.

[0065] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft, characterized in that, Including those that are stacked and combined in sequence: The first layer of sound barrier consists of a nanoporous aerogel board, the second layer of sound-absorbing and noise-reducing material board, and the third layer of sound barrier consists of a rigid foam material board. The three-layer structure is bonded together with adhesive to form an integrated composite structure with a total thickness of ≤50mm and a surface density of ≤2kg / m², and constitutes a noise reduction structure with varying acoustic impedance gradient.

2. The full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft according to claim 1, characterized in that, The nanoporous aerogel board is any one of silica aerogel felt board, alumina aerogel board, carbon aerogel board or cellulose aerogel board.

3. The full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft according to claim 2, characterized in that, The nanoporous aerogel board is a silica aerogel felt board with a density ≤360kg / m³, used for heat radiation isolation.

4. The full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft according to claim 3, characterized in that, The silica aerogel felt board comprises a flexible felt material matrix and silica aerogel blocks. Silica aerogel blocks with different solid contents are filled and solidified in the fiber gaps of flexible felt material matrices of different densities. After aging, hydrophobic modification, and supercritical CO2 drying, lightweight silica aerogel felt boards of different densities are formed.

5. The full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft according to claim 1, characterized in that, The porous sound-absorbing material board is any one of melamine foam material board, sound-absorbing cotton, meltblown glass wool, or meltblown basalt wool.

6. The full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft according to claim 5, characterized in that, The rigid foam material board is any one of rigid PU polyurethane foam board, XPS foam extruded board, PE board, PP board, PEEK board, aluminum foam board, or titanium foam board.

7. The full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft according to claim 6, characterized in that, The porous sound-absorbing material board is a melamine foam material board, and the rigid foam material board is a rigid PU polyurethane foam board.

8. The method for preparing the full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft according to claim 1, characterized in that, Includes the following steps: S1. Material preparation: Prepare nanoporous aerogel boards, porous sound-absorbing material boards, and rigid foam material boards; S2. Cutting: Cut the three-layer material board according to the predetermined dimensions; S3. Adhesive bonding: Apply adhesive between the nanoporous aerogel board and the porous sound-absorbing material board, and between the porous sound-absorbing material board and the rigid foam material board, and press them together to form a three-layer composite structure. S4. Reinforcement: The three-layer composite structure is fixed by through-riveting with nylon nails; S5. Inspection: Test the thickness, surface density and sound insulation performance of the components to ensure that the sound insulation at 250Hz is ≥20dB, the sound insulation at 500Hz is ≥25dB ​​and the sound insulation at 1000Hz is ≥25dB. S6. Packaging and Delivery: Protectively package and deliver qualified components.

9. The method for preparing the full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft according to claim 8, characterized in that, In step S3, the adhesive is a high-temperature resistant epoxy resin or polyurethane structural adhesive, the coating thickness of the adhesive is 0.1-0.36 mm, the curing temperature is ≤80℃, and the curing time is 20-40 min; in step S4, the distribution density of nylon nails is 4-6 per square meter.

10. The application of the full-frequency domain strong sound insulation and noise reduction silica aerogel felt assembly for rotorcraft according to claim 1, characterized in that, The silica aerogel felt assembly can be used for sound insulation, noise reduction, and thermal insulation applications in the interiors of rotorcraft, flying cars, seaplanes, and turbofan engines.

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