Acoustic liner, power propulsion system and noise reduction method

Abstract

The invention relates to an acoustic liner, a power propulsion system and a noise reduction method. The acoustic liner comprises a shell, a perforated plate is arranged on the first end face of the shell, a back plate is arranged on the second end face of the shell, and a sound absorption cavity is defined by the first end face, the second end face and the wall face of the shell; the porous medium layer is located in the sound absorption cavity and divides the sound absorption cavity into a first sound absorption cavity and a second sound absorption cavity; and the piezoelectric crystal is connected with the porous dielectric layer, and the piezoelectric crystal can deform after being electrified so as to drive the porous dielectric layer to deform and change the volume ratio of the first sound absorption cavity to the second sound absorption cavity.

Description

Technical Field

[0001] The invention relates to a sound lining component, a power propulsion system and a noise reduction method. Background Art

[0002] The power propulsion system, such as the turbofan engine commonly used in gas turbine engines as a civil aviation engine, has the following operating principles: the outside atmosphere first passes through the air intake nacelle equipped with an acoustic liner, then flows through a large-sized fan, and then is divided into two airflows. One part of the airflow is discharged through the fan outlet; the other part of the airflow is the mainstream airflow, which is pressurized by the boost stage and the high-pressure compressor in turn, and becomes high-temperature, high-pressure combustion gas after combustion in the combustion chamber, and then expands and works in the high-pressure turbine and the low-pressure turbine, and is discharged from the outlet. The rotating shafts of the engine are the connecting shafts of the high-pressure compressor and the high-pressure turbine, and the connecting shafts of the fan, the boost stage and the low-pressure turbine.

[0003] The noise problem of civil aviation engines poses an important issue for the continuously growing aviation transportation industry. The noise level is directly related to the acquisition of engine airworthiness certification. This is undoubtedly a huge challenge for the civil aviation engines that are being developed in my country. The noise level of large civil aircraft is one of the important contents of airworthiness certification. The noise certification standards are constantly changing over time. Annex 16 of the International Civil Aviation Organization (ICAO) has made detailed technical specifications for aircraft noise certification. This technical specification adopts the "Effective Perceived Noise Level" (EPNL) and considers three certification benchmark conditions: Sideline, Cutback, and Approach. EPNL is used to quantify aircraft noise and consider the perceived annoyance based on noise measurement. Approach: The state of the aircraft preparing to land on the runway. The airworthiness standards of different aircraft are different. The meaning of each condition is as follows: flyover: the state of the aircraft taking off and rolling for a certain distance, and the airworthiness standards of different aircraft are different; sideline: the state of the maximum noise level after the aircraft leaves the ground, and the airworthiness standards of different aircraft are different; sound pressure level (Sound Power Level) refers to the logarithm of the ratio of sound power to reference sound power multiplied by 10, unit decibel blade passing frequency (BPF): the noise frequency caused by the blade passing the tongue of the volute, also known as the fundamental frequency. The fan is a typical fluid machine. The airflow flows between the rotating rotor and the stator blade row, generating strong single-tone noise and broadband noise. The fan blades of aircraft engines widely adopt a design with a small number of blades and a wide chord length. The working points that are most concerned about external field noise are approach landing and takeoff. The blade tip Mach number is at a subsonic blade tip speed. The fan noise spectrum is characterized by the blade passing frequency single tone and its harmonics superimposed in the broadband noise spectrum.

[0004] Acoustic lining is a common means of controlling turbine noise. The structure of acoustic lining can include single-degree-of-freedom acoustic lining, double-degree-of-freedom acoustic lining and multi-degree-of-freedom acoustic lining. Single-degree-of-freedom acoustic lining is the earliest form of honeycomb acoustic lining structure, which is composed of perforated plate, honeycomb layer core and rigid back plate. This structure has the advantages of simple process, small structure thickness, convenient structure layout, etc., and is widely used. Double-degree-of-freedom acoustic lining structure includes two honeycomb cores superimposed, that is, it is composed of perforated plate, honeycomb core, middle layer, honeycomb core and back plate. The middle layer can adopt perforated plate, metal mesh, sound-absorbing film with micro holes, embedded sound-absorbing structure and other structures. The embedded sound-absorbing structure can realize non-equal height design according to acoustic needs. Double-degree-of-freedom acoustic lining increases the weight and production cost of the acoustic lining, but the double-degree-of-freedom acoustic lining uses two resonators in series, which can broaden the sound absorption frequency band of the acoustic lining and significantly reduce noise. The multi-degree-of-freedom sound-absorbing structure is to change a single-layer honeycomb into a multi-layer honeycomb, and add a layer of porous plate between each honeycomb layer. However, this sound-absorbing structure has certain problems in use. For example, when the micro-perforated plate is bonded to the honeycomb core material, it is necessary to ensure that the holes are not blocked during the bonding process. In addition, the mechanical properties of the multi-degree-of-freedom sound-absorbing sound lining are greatly reduced during the design and preparation process. At the same time, the addition of the micro-perforated plate has greatly increased the weight of the material itself. Therefore, a porous material diaphragm intermediate layer can be set in the honeycomb core to avoid excessive weight and improve the acoustic performance of the sound lining. The sound-absorbing principle of the sound lining can be regarded as a combination of a large number of Helmholtz resonance cavities, taking the simplest degree-of-freedom sound lining as an example. The acoustic resistance is determined by the micropores, and the size of the resonance cavity determines its resonant frequency, that is, the acoustic reactance. After the sound wave of a specific frequency enters the honeycomb cavity through the small holes on the perforated plate, it will resonate, so that the sound energy is converted into internal energy and consumed. In this way, the two cooperate to achieve the purpose of noise reduction at a specific frequency.

[0005] The schemes and concepts for improving the sound-absorbing effect of the sound lining include the panel hole structure design, the honeycomb core structure design and the addition of other sound-absorbing structures. It is also possible to set a porous material lining core and increase the layer structure in the honeycomb core to improve the noise reduction performance, as well as set a multi-section diaphragm structure, absorber, lining core inside the honeycomb core and set a perforated plate, cotton felt sound absorption and other layer structures between the panel and the core material.

[0006] However, the inventors have found that due to the existence of airworthiness noise regulations, the low-noise design of the fan is required to take into account as many operating conditions as possible, such as the aforementioned sideline, flyover, and approach conditions. However, the current sound lining design can only take one main fundamental frequency as the noise reduction target each time, and through forward optimization iterative design, take into account the fundamental frequencies corresponding to other operating conditions as much as possible to obtain a local optimal solution for the total noise. Such noise reduction effect needs to be improved.

[0007] Therefore, there is a need in the art for an acoustic lining component, a power propulsion system, and a noise reduction method so that the acoustic lining can take into account the noise reduction effect of the fundamental frequency corresponding to more working conditions. Summary of the invention

[0008] An object of the present invention is to provide an acoustic lining.

[0009] Another object of the present invention is to provide a power propulsion system.

[0010] Another object of the present invention is to provide a noise reduction method.

[0011] According to one aspect of the present invention, an acoustic lining comprises a shell, a first end face of the shell providing a perforated plate, a second end face providing a back plate, the first end face, the second end face and the wall face of the shell defining a sound absorption chamber; a porous medium layer located inside the sound absorption chamber and dividing the sound absorption chamber into a first sound absorption chamber and a second sound absorption chamber; and a piezoelectric crystal connected to the porous medium layer, the piezoelectric crystal being able to deform after being energized to drive the porous medium layer to deform and change the volume ratio of the first sound absorption chamber to the second sound absorption chamber.

[0012] In the scheme of the acoustic lining introduced above, by adopting the means of piezoelectric crystals and porous medium layers, the size of the resonance cavity that plays a sound-absorbing role can be adjusted according to different working conditions, so that different working conditions correspond to different acoustic cavity sizes of the Helmholtz resonator, thereby corresponding to different target noise reduction frequencies. In this way, the same acoustic lining can achieve targeted noise reduction processing for specific noise frequencies under different working conditions, so that the acoustic lining can take into account the fundamental frequencies corresponding to various working conditions, thereby improving the noise reduction effect.

[0013] A power propulsion system according to another aspect of the present invention comprises any one of the above-mentioned acoustic lining components.

[0014] In one or more embodiments of the power propulsion system, the power propulsion system is a gas turbine engine, and the acoustic lining is disposed in a nacelle of the gas turbine engine.

[0015] According to another aspect of the present invention, a noise reduction method for a power propulsion system adopts the above-mentioned sound lining member, and the noise reduction method includes: in a first operating condition of the power propulsion system, the volume ratio of the first sound absorption chamber to the second sound absorption chamber is a first volume ratio; in a second operating condition of the power propulsion system, the volume ratio of the first sound absorption chamber to the second sound absorption chamber is a second volume ratio; the first volume ratio is different from the second volume ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which:

[0017] Figure 1A , Figure 1BIt is a schematic structural diagram of a cross-sectional view of an acoustic lining member of an embodiment.

[0018] Figure 2 It is a schematic diagram of the installation structure of the piezoelectric crystal of the acoustic lining member according to one embodiment.

[0019] Figure 3 It is a structural schematic diagram of the function of the piezoelectric crystal of the acoustic lining member of one embodiment.

[0020] Reference numerals:

[0021] 10- Acoustic Lining

[0022] 1- Shell

[0023] 11-Perforated plate

[0024] 12-Back panel

[0025] 101-first end surface

[0026] 102- Second end surface

[0027] 103-Wall

[0028] 100-Sound absorption chamber

[0029] 1001-First sound absorption chamber

[0030] 1002-Second sound absorption chamber

[0031] 2-Porous medium layer

[0032] 201-First position

[0033] 202-Second position

[0034] 3-Piezoelectric crystal

[0035] 31-Electrode pad. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with specific embodiments and drawings. More details are elaborated in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from the description herein. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0037] At the same time, the present application uses specific words to describe the embodiments of the present application, such as "one embodiment", "an embodiment", and / or "some embodiments" to refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" mentioned twice or more in different locations in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0038] The acoustic lining components described in the following embodiments are applied to gas turbine engines, specifically, the nacelle of a turbofan engine as an example, but are not limited to this. They are applicable to all power propulsion systems, including power propulsion systems with fans, blades, propeller fans, etc., and are not limited to gas turbine engines. For example, they may be a hybrid propulsion system including a gas turbine engine, or a purely electrically driven power propulsion system with fans, blades, and propeller fans to reduce fan noise and / or intake noise.

[0039] refer to Figure 1A , Figures 1B to 3 As shown, in some embodiments, the acoustic lining member 10 may include a shell 1 , a porous medium layer 2 and a piezoelectric crystal 3 .

[0040] The first end surface 101 of the housing 1 provides a perforated plate 11 , and the second end surface 102 provides a back plate 12 . The first end surface 101 , the second end surface 102 and the wall surface 103 of the housing define a sound absorbing chamber 100 .

[0041] The porous medium layer 2 is located inside the sound absorption chamber 100, and divides the sound absorption chamber 100 into a first sound absorption chamber 1001 and a second sound absorption chamber 1002. That is, the porous medium layer 2 is equivalent to a partition, which divides the sound absorption chamber 100 into a first sound absorption chamber 1001 and a second sound absorption chamber 1002. The two are generally only connected through the small holes of the porous medium layer 2, and there is no other connection path. Preferably, in some embodiments, the porous medium layer 2 can be a film (or a thin plate) structure, that is, a planar structure, so that the structure is simple, easy to process and set the corresponding deformation and the relationship between the volume ratio of the first sound absorption chamber and the second sound absorption chamber. Preferably, in some embodiments, its porosity is 5%-15%, and the material can be a common flexible porous material, such as silica gel.

[0042] like Figure 2 as well as Figure 3 As shown, the piezoelectric crystal 3 is connected to the porous medium layer 2 , and the piezoelectric crystal 3 can deform after being energized to drive the porous medium layer 2 to deform, thereby changing the volume ratio of the first sound absorption chamber 1001 and the second sound absorption chamber 1002 .

[0043] like Figures 1A to 3As shown, in some embodiments, the piezoelectric crystal 3 is a sheet structure (hereinafter also referred to as a "piezoelectric sheet"), which is bonded to the porous medium layer 2. In some embodiments, the material of the piezoelectric sheet can be piezoelectric ceramics or quartz crystal materials, or PVDF piezoelectric film. Figure 2 As shown, in some embodiments, by attaching electrodes 31 on both sides of the piezoelectric sheet, the piezoelectric sheets are grouped and connected, and different voltages are set, a multi-band noise reduction effect can be achieved.

[0044] Specifically, if Figure 1A , Figure 1B As shown, when not powered, the acoustic liner 10 can be regarded as a double-freedom sound-absorbing plate, which can achieve noise reduction in two frequency bands. That is, the acoustic liner 10 is in the initial state, the piezoelectric crystal 3 is in the non-powered state, the porous medium layer 2 is located at the first position 201, the first sound-absorbing chamber 1001 corresponds to the first noise reduction frequency, and the second sound-absorbing chamber 1002 corresponds to the second noise reduction frequency. Figure 3 As shown, after power is turned on, the acoustic lining 10 is in an adjustment state, the piezoelectric crystal 3 will deform, driving the porous medium layer 2 of the thin film structure to deform to the second position 202, changing the volume of the upper and lower cavities, that is, changing the volume of the first sound absorption chamber 1001 and the second sound absorption chamber 1002, so that the first sound absorption chamber 1001 corresponds to the third noise reduction frequency, and the second sound absorption chamber 1002 corresponds to the fourth noise reduction frequency, thereby achieving different acoustic cavity sizes of the Helmholtz resonator corresponding to different working conditions, thereby corresponding to different target noise reduction frequencies, so that the same acoustic lining can achieve targeted noise reduction processing for specific noise frequencies under different working conditions, so that the acoustic lining can take into account the fundamental frequencies corresponding to various working conditions, thereby improving the noise reduction effect.

[0045] It can be noted that the embodiment shown in the figure is different from the traditional sound lining. It does not have a honeycomb core in the sound absorption chamber. Its sound elimination principle is that the Helmholtz resonator can be simplified as a spring damping system. The neck air can be regarded as a mass block, and the air in the cavity can be regarded as a spring. Its sound absorption frequency can be expressed by the formula: Among them, V0 is the cavity volume, S0 is the neck cross-sectional area, and L0 is the neck height. It can be seen that by adjusting the cavity volume, the sound absorption frequency of the sound-absorbing panel can be effectively adjusted.

[0046] Targeted sound absorption effect can be achieved by adjusting the voltage value of the piezoelectric film, and multi-band sound absorption can be achieved.

[0047] As described above, the present application also includes a noise reduction method, using the acoustic lining member 10 described in the above embodiment, the noise reduction method includes:

[0048] In the first working condition of the power propulsion system, the volume ratio of the first sound absorbing chamber 1001 to the second sound absorbing chamber 1002 is a first volume ratio;

[0049] In the second working condition of the power propulsion system, the volume ratio of the first sound absorbing chamber 1001 to the second sound absorbing chamber 1002 is a second volume ratio;

[0050] Wherein, the first volume ratio is different from the second volume ratio.

[0051] In some embodiments, a specific way of changing the first volume ratio and the second volume ratio may be to apply different voltage values ​​to the acoustic liner 10 to change the volume ratio of the first sound absorbing chamber 1001 and the second sound absorbing chamber 1002 .

[0052] For example, the first working condition can be set as the approach working condition. For the initial state of the acoustic lining member 10, the first sound absorption chamber 1001 can correspond to the first noise reduction frequency, and the second sound absorption chamber 1002 can correspond to the second noise reduction frequency, which can be applicable to the approach working condition. For example, when the working condition is the overflight working condition, the voltage of the piezoelectric crystal 3 can be adjusted so that the volume of the first sound absorption chamber 1001 and the second sound absorption chamber 1002 changes to the corresponding noise reduction frequency, which can be applicable to the overflight working condition. When the working condition is the sideline working condition, the voltage of the piezoelectric crystal 3 can be further adjusted so that the volume of the first sound absorption chamber 1001 and the second sound absorption chamber 1002 changes to the corresponding noise reduction frequency, which can be applicable to the sideline working condition.

[0053] In summary, the beneficial effects of the acoustic lining components, power propulsion systems, and noise reduction methods introduced in the above embodiments include, but are not limited to, by adopting piezoelectric crystals and porous medium layers, the size of the resonance cavity that plays a sound-absorbing role can be adjusted according to different working conditions, so that different working conditions correspond to different acoustic cavity sizes of the Helmholtz resonator, thereby corresponding to different target noise reduction frequencies. In this way, the same acoustic lining can achieve targeted noise reduction processing for specific noise frequencies under different working conditions, so that the acoustic lining can take into account the fundamental frequencies corresponding to various working conditions, thereby improving the noise reduction effect.

[0054] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. An acoustic lining member (10), characterized in that: include: A shell (1), wherein a first end surface (101) of the shell (1) provides a perforated plate (11), and a second end surface (102) provides a back plate (12), and the first end surface (101), the second end surface (102) and the wall surface (103) of the shell define a sound absorption chamber (100); A porous medium layer (2) is located inside the sound absorption chamber (100) and divides the sound absorption chamber (100) into a first sound absorption chamber (1001) and a second sound absorption chamber (1002); A piezoelectric crystal (3) is connected to the porous medium layer (2), and the piezoelectric crystal (3) can deform after being energized, thereby driving the porous medium layer (2) to deform and changing the volume ratio of the first sound absorption chamber (1001) to the second sound absorption chamber (1002).

2. The acoustic lining member (10) according to claim 1, characterized in that: The porous medium layer (2) is a film-like structure.

3. The acoustic lining member (10) according to claim 2, characterized in that: The porosity of the thin-film porous medium layer (2) is 5%-15%; the material is silica gel.

4. The acoustic lining member (10) according to claim 1, characterized in that: The acoustic lining member (10) comprises an initial state and an adjustment state. In the initial state, the piezoelectric crystal (3) is in a non-energized state, the porous medium layer (2) is located at a first position (201), the first sound absorption chamber (1001) corresponds to a first noise reduction frequency, and the second sound absorption chamber (1002) corresponds to a second noise reduction frequency; in the adjustment state, the piezoelectric crystal (3) is in a energized state, the porous medium layer (2) is located at a second position (202) as the piezoelectric crystal (3) is deformed, the first sound absorption chamber (1001) corresponds to a third noise reduction frequency, and the second sound absorption chamber (1002) corresponds to a fourth noise reduction frequency.

5. The acoustic lining member (10) according to claim 4, characterized in that: The piezoelectric crystal (3) is a sheet-like structure and is bonded to the porous medium layer (2).

6. The acoustic lining member (10) according to claim 5, characterized in that: The sheet-shaped piezoelectric crystal (3) is connected to electrode sheets (31) located on both sides thereof.

7. A power propulsion system, characterized in that: It comprises the acoustic lining member (10) as claimed in any one of claims 1 to 6.

8. The propulsion system according to claim 7, characterized in that: The power propulsion system is a gas turbine engine, and the acoustic lining component (10) is arranged in the nacelle of the gas turbine engine.

9. A noise reduction method for a power propulsion system, characterized in that: Using the acoustic lining member (10) according to any one of claims 1 to 6, the noise reduction method comprises: In a first operating condition of the power propulsion system, a volume ratio of the first sound absorption chamber (1001) to the second sound absorption chamber (1002) is a first volume ratio; In a second operating condition of the power propulsion system, the volume ratio of the first sound absorption chamber (1001) to the second sound absorption chamber (1002) is a second volume ratio; The first volume ratio is different from the second volume ratio.

10. The noise reduction method according to claim 9, characterized in that: Different voltage values ​​are applied to the acoustic lining member (10) to change the volume ratio of the first sound absorbing chamber (1001) to the second sound absorbing chamber (1002).

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