Sound liner device with adjustable noise reduction frequency band based on folding structure

Abstract

The invention discloses a noise reduction frequency band adjustable acoustic liner device based on a folding structure, which comprises a perforated panel, a honeycomb sandwich and a back plate, the honeycomb sandwich is composed of a plurality of honeycomb single cavities arranged in an array, the lower end of the honeycomb sandwich is fixed on the back plate, the perforated panel covers the upper end of the honeycomb sandwich, the perforated panel is provided with a plurality of panel through holes, and the panel through holes are communicated with the honeycomb sandwich. The panel penetrating holes are communicated with the honeycomb single cavities, folding structures are placed at the bottoms of the honeycomb single cavities, the folding structures can adjust the size and height of the folding structures through folding or stretching, then the cavity size of the honeycomb single cavities is changed, and the resonant frequency of the honeycomb single cavities is adjusted. Resonant frequency deviation of the resonant cavity is achieved through the folding structure, and the effect that the sound absorption frequency of the acoustic liner is adjustable is achieved. Meanwhile, a telescopic motor is combined with an adjusting plate and a pull rod, synchronous adjustment of all folding structures is achieved, the number of adopted assemblies is small, the structure is simple, and the good engineering application value is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of acoustic noise reduction, and in particular to a noise reduction frequency band adjustable sound lining device based on a folding structure. Background Art

[0002] The mechanism of noise generation is that the sound source propagates irregularly in the form of waves in solid, gas, liquid and other media. Noise pollution, as one of the four major environmental pollutions, not only pollutes the surrounding environment, but also harms human health. In the industrial field, the rapid development of the aviation industry in recent years has brought great convenience to people's lives. Although aircraft have become an important means of modern transportation, the noise they generate also brings serious environmental pollution problems, affecting the riding comfort of passengers, and has become one of the major issues of aircraft design and environmental protection. During takeoff, landing and level flight, various types of noise will be generated. Generally speaking, it can be divided into two parts: engine noise and fuselage noise. Among them, engine noise is the main source. Therefore, the key to aircraft noise reduction is engine noise control. Technologies for reducing engine noise include: sound-absorbing bushings and fairings, improving bypass ratio, flow control noise reduction technology, etc. Among them, nacelle sound lining noise reduction technology has the most development potential in the noise problem of engines. Sound lining is a noise suppression element derived from the model of resistive muffler. It is widely used in the engine nacelle of aviation turbofan engines, mainly distributed on the inner wall of the engine nacelle. The typical sound lining structure is mainly composed of a resonance cavity, a perforated panel and a back panel. With the increasing requirements for the noise reduction effect of the sound lining, the single perforated plate sound lining has gradually transitioned to a composite perforated plate sound absorption structure. The use and research of sound lining has a history of more than 70 years. New sound lining designs such as multi-degree-of-freedom design and foam metal design have also emerged in recent years. However, due to the fixed limitations of its own geometric parameters and material properties, the conventional sound lining structure has a narrow noise reduction bandwidth and the frequency range is not adjustable. Based on this, the development of a high-performance low-frequency broadband vibration and noise reduction lining structure with adjustable frequency band is a technical problem that needs to be solved urgently by technicians in this field. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a noise reduction frequency band adjustable sound liner device based on a folding structure in view of the above-mentioned deficiencies of the prior art, so as to overcome the problem that the sound absorption frequency of the sound liner in the prior design cannot be adjusted.

[0004] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0005] A noise reduction frequency band adjustable sound lining device based on a folding structure comprises a perforated panel, a honeycomb core and a back plate, wherein the honeycomb core is composed of a plurality of honeycomb single cavities arranged in an array, the lower end of the honeycomb core is fixed on the back plate, the perforated panel covers the upper end of the honeycomb core, a plurality of panel perforations are arranged on the perforated panel, the panel perforations are connected with the honeycomb single cavity, a folding structure is placed at the bottom of the honeycomb single cavity, the folding structure can adjust its own volume and height by folding or stretching, thereby changing the volume of the honeycomb single cavity and adjusting the resonance frequency of the honeycomb single cavity.

[0006] To optimize the above technical solutions, the specific measures taken also include:

[0007] The above-mentioned folding structure includes an upper flat section, a bending section and a lower flat section. The bending section is arranged between the upper flat section and the lower flat section. The bending section is a hollow cylindrical structure formed by splicing a number of creased plates. The bending section can bend toward the inside or outside of the hollow cylindrical structure along each creased plate connection, thereby changing the volume and height of the folding structure.

[0008] The above-mentioned noise reduction frequency band adjustable sound lining device also includes an adjustment structure, which includes an adjustment plate, a pull rod and a telescopic motor. The lower flat plate section is fixedly installed on the bottom of the honeycomb single cavity, the upper end of the pull rod is fixed on the upper flat plate section, the adjustment plate is located below the back plate, and the lower end of each pull rod passes through the back plate and is fixedly connected to the adjustment plate. The telescopic motor is fixed on the adjustment plate, and the telescopic shaft of the telescopic motor is connected to the lower surface of the back plate. The telescopic motor drives the adjustment plate to move up and down by telescoping, thereby causing the pull rod to pull the folding structure to unfold or fold.

[0009] The middle part of the pull rod passes through the lower flat plate section.

[0010] The upper end of the pull rod is fixedly connected to the upper flat plate section through two upper and lower nuts, wherein the upper nut is located above the upper flat plate section, and the lower nut is located below the upper flat plate section. The upper nut and the lower nut are both screwed on the pull rod, and the upper nut and the lower nut clamp the upper flat plate section.

[0011] The upper flat plate section is provided with a folding structure through hole, which is communicated with the hollow columnar structure formed by the bending section.

[0012] The above honeycomb single cavity is a regular hexagonal honeycomb.

[0013] The perforated panel and back panel are made of metal materials.

[0014] The perforated panel and back panel are made of composite materials.

[0015] The above-mentioned folding structure is made of non-metallic material.

[0016] The present invention has the following advantages:

[0017] 1. The present invention sets a folding structure in the resonance cavity (i.e., honeycomb single cavity) of the acoustic liner, and uses the foldable and expandable characteristics of the folding structure to adjust the cavity volume, thereby achieving a resonance frequency shift of the resonance cavity and achieving an adjustable sound absorption frequency effect of the acoustic liner.

[0018] 2. The present invention realizes synchronous adjustment of the entire folding structure by combining a telescopic motor with an adjustment plate and a pull rod. It uses a small number of components and has a simple structure, and has certain engineering application value.

[0019] 3. The present invention provides a folding structure through hole on the upper flat plate section, so that the folding structure also forms a separate resonance cavity. By adjusting the volume of the folding structure, the sound lining device can have a dual-frequency sound absorption function, thereby enabling the device of the present invention to adapt to scenes with dual-frequency sound absorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the sound liner structure in the first embodiment of the present invention;

[0021] Figure 2 is a structural diagram of a folding structure in a first embodiment of the present invention;

[0022] Figure 3 It is a schematic diagram of the resonance cavity structure of the present invention;

[0023] Figure 4 This is a schematic diagram of the bending section structure of the present invention ( Figure 3 , Figure 4 The units of the figures are all mm);

[0024] Figure 5 is a transmission loss diagram of the acoustic liner unit in different folding and unfolding states when Ma=0 in the first embodiment;

[0025] Figure 6 is a schematic diagram of changes in the resonance frequency of the acoustic liner under three folding and unfolding states of each tangential flow in the first embodiment;

[0026] Figure 7 It is a schematic diagram of the sound liner structure in the second embodiment of the present invention.

[0027] In the figure, the reference numerals are: perforated panel 1, panel perforation 11, honeycomb core 2, folding structure 3, upper flat section 31, bending section 32, lower flat section 33, folding structure through hole 34, back plate 4, adjustment structure 5, adjustment plate 51, pull rod 52, telescopic motor 53, upper nut 54, lower nut 55. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0029] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0030] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0031] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or units (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" / "several" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0032] First embodiment:

[0033] refer to Figure 1 A noise reduction frequency band adjustable sound lining device based on a folding structure comprises a perforated panel 1, a honeycomb core 2, a back plate 4 and a folding structure 3, wherein the folding structure 3 is arranged between the perforated panel 1 and the back plate 4, the perforated panel 1 is provided with panel perforations 11, the folding structure 3 is formed by splicing a plurality of creased plates, and the volume of the cavity of the honeycomb core 2 is changed differently through different folding and unfolding states, and the panel perforations 11 on the perforated panel 1 are directly opposite to the cavity of the honeycomb core 2 to form a Helmholtz resonance cavity to produce sound absorption.

[0034] refer to Figure 2 The adjustment structure 5 includes an adjustment plate 51, a pull rod 52 and a telescopic motor 53. Each folding structure 3 is equipped with two pull rods 52, which are respectively arranged on the left and right sides of the folding structure 3. The pull rods 52 pass through the upper flat section 31, the lower flat section 33 and the back plate 44 at the same time, and are fixed to the adjustment plate 51. The telescopic motor 53 is fixed to the adjustment plate 51. The telescopic shaft of the telescopic motor 53 is connected to the lower surface of the back plate 4. When the telescopic shaft of the telescopic motor 53 is extended or retracted, the adjustment plate 51 pulls the folding structure 3 to be unfolded or folded through the pull rod 52.

[0035] refer to Figure 3,For the main parameters of the sound lining structure: porosity, hole diameter, thickness of perforated panel 1 and resonance cavity depth, the porosity of perforated panel 1 is 0.011, the hole diameter is 0.99mm, the thickness of perforated panel 1 is 0.64mm, and the resonance cavity depth is 20mm.

[0036] refer to Figure 4 For the bending section 32 of the folding structure 3, its length and width are both 6 mm, and its height is 6.79 mm, wherein the height is only the height during the folding process, and the height will change at different folding degrees. The height in the maximum unfolded state is 7.36 mm.

[0037] The perforated panel 1 and the back panel 4 can be made of metal material or composite material, and the folding structure 3 can be made of non-metal material. The folding structure 3 can also be made of metal material.

[0038] The working principle of the sound lining device of the present invention is as follows:

[0039] When the noise sound wave passes through the perforated panel 11 tangentially and passes through the panel perforations 11, it will be divided into two branches: (1) enter the resonance cavity from the small hole and stimulate a certain mass of air in the resonance cavity to move; (2) continue to propagate forward. When the size of the resonance cavity is much smaller than the wavelength of the external sound wave in the pipeline, its neck air column will reciprocate like a piston, and when its natural frequency is equal to the frequency of the noise sound wave, the resonance cavity air column and the pipeline sound wave will resonate, and the neck air column will make the strongest forced motion, converting the sound energy into internal energy, thereby achieving the maximum sound absorption effect. Figure 5 It can be seen that the resonance frequency of the acoustic liner in the undeployed state is 1550 Hz.

[0040] The folding and unfolding driving method of the folding structure 3 in the cavity adopts the method of combining the telescopic motor 44 with the adjustment plate 51 and the pull rod 52 to realize the folding and unfolding of the folding structure 3. Under the condition of Mach number Ma=0, as the folding structure 3 is gradually unfolded, the maximum transmission loss of the resonance cavity gradually decreases from 5.22dB to 4.83dB, and the resonance frequency shifts to high frequency from 1550Hz to 1600Hz, and then to 1650Hz; Figure 6 As shown in Figure 2, when Ma = 0.05 and 0.1, the changes in the three folding forms have little effect on the transmission loss. However, it can be seen from the resonance frequency that as the folding structure 3 unfolds, the resonance frequency still gradually shifts to high frequency. The specific shift is shown in Figure 5 .

[0041] Second embodiment:

[0042] like Figure 7As shown, a folding structure through hole 34 is opened on the folding structure 3, and the folding structure through hole 34 is connected to the hollow columnar structure formed by the bending section 32, so that the folding structure 3 forms a separate resonance cavity, and the rest of the structure is the same as the first embodiment.

[0043] This embodiment enables the folded structure 3 to have a double resonance cavity, thereby obtaining a dual-frequency sound absorption function to adapt to the scene with dual-frequency sound absorption.

[0044] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A noise reduction frequency band adjustable sound lining device based on a folding structure, comprising a perforated panel (1), a honeycomb core (2) and a back plate (4), wherein the honeycomb core (2) is composed of a plurality of honeycomb single cavities arranged in an array, the lower end of the honeycomb core (2) is fixed on the back plate (4), the perforated panel (1) covers the upper end of the honeycomb core (2), the perforated panel (1) is provided with a plurality of panel perforations (11), and the panel perforations (11) are connected to the honeycomb single cavities, wherein: A folding structure (3) is placed at the bottom of the honeycomb single cavity. The folding structure (3) can adjust its own volume and height by folding or stretching, thereby changing the volume of the honeycomb single cavity and adjusting the resonance frequency of the honeycomb single cavity.

2. According to claim 1, a noise reduction frequency band adjustable sound lining device based on a folded structure is characterized by: The folding structure (3) comprises an upper flat section (31), a bending section (32) and a lower flat section (33); the bending section (32) is arranged between the upper flat section (31) and the lower flat section (33); the bending section (32) is a hollow columnar structure formed by splicing a plurality of creased plates; the bending section (32) can bend toward the inside or outside of the hollow columnar structure along each creased plate connection, thereby changing the volume and height of the folding structure (3).

3. The noise reduction frequency band adjustable sound lining device based on the folded structure according to claim 2 is characterized by: The noise reduction frequency band adjustable sound lining device also includes an adjustment structure (5), the adjustment structure (5) includes an adjustment plate (51), a pull rod (52) and a telescopic motor (53), the lower flat section (33) is fixedly mounted on the bottom of the honeycomb single cavity, the upper end of the pull rod (52) is fixed on the upper flat section (31), the adjustment plate (51) is located below the back plate (4), the lower end of each pull rod (52) passes through the back plate (4) and is fixedly connected to the adjustment plate (51), the telescopic motor (53) is fixed on the adjustment plate (51), the telescopic shaft of the telescopic motor (53) is connected to the lower surface of the back plate (4), and the telescopic motor (53) drives the adjustment plate (51) to move up and down by telescoping, thereby causing the pull rod (52) to pull the folding structure (3) to unfold or fold.

4. The noise reduction frequency band adjustable sound lining device based on a folded structure according to claim 3 is characterized by: The middle portion of the pull rod (52) passes through the lower flat plate section (33).

5. The noise reduction frequency band adjustable sound lining device based on the folded structure according to claim 4 is characterized by: The upper end of the pull rod (52) is fixedly connected to the upper flat section (31) via two upper and lower nuts, wherein the upper nut (54) is located above the upper flat section (31) and the lower nut (55) is located below the upper flat section (31). The upper nut (54) and the lower nut (55) are both screwed onto the pull rod (52), and the upper nut (54) and the lower nut (55) clamp the upper flat section (31) at the same time.

6. The noise reduction frequency band adjustable sound lining device based on the folded structure according to claim 5 is characterized by: The upper flat plate section (31) is provided with a folding structure through hole (34), and the folding structure through hole (34) is connected to the hollow columnar structure formed by the bending section (32).

7. The noise reduction frequency band adjustable sound lining device based on a folded structure according to claim 1 is characterized by: The honeycomb single cavity is a regular hexagonal honeycomb.

8. The noise reduction frequency band adjustable sound lining device based on a folded structure according to claim 1 is characterized by: The perforated panel (1) and the back panel (4) are made of metal material.

9. The noise reduction frequency band adjustable acoustic lining device based on a folded structure according to claim 1 is characterized by: The perforated panel (1) and the back panel (4) are made of composite materials.

10. The noise reduction frequency band adjustable sound lining device based on a folded structure according to claim 1 is characterized by: The folding structure (3) is made of non-metallic material.

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