Aero-engine acoustic liner structure based on polymorphic three-period minimal curved surface and construction method

Abstract

The invention belongs to the technical field of engine sound insulation and noise resistance, and particularly discloses an aero-engine acoustic liner structure based on a polymorphic three-period minimal curved surface and a construction method.The aero-engine acoustic liner structure comprises a micro-perforated plate, a polymorphic TPMS core layer is fixedly connected under the micro-perforated plate, the polymorphic TPMS core layer comprises P-type TPMS cell elements and I-WP-type TPMS cell elements, and the P-type TPMS cell elements and the I-WP-type TPMS cell elements are connected with the micro-perforated plate. The P-type TPMS cell element and the I-WP-type cell element are gradually connected into a whole through a Sigmoid function, and the lower end of the polymorphic TPMS core layer is fixedly connected with the rigid panel. The low-frequency sound absorption material has excellent low-frequency sound absorption performance, and the noise of the aero-engine is effectively controlled within the low-frequency range of 100-400 Hz; the material shows a double-platform stress characteristic in the aspect of mechanical properties, and has excellent energy absorption capacity; besides, TPMS structures with different sizes, types and porosities can be designed by adjusting TPMS structure parameters, and the multi-form TPMS structure is multifunctional and has more flexible design freedom.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of engine sound insulation and noise reduction, and particularly relates to an aero-engine sound lining structure based on a multi-form triply periodic minimal surface and a construction method. BACKGROUND

[0002] Aero-engine noise is a complex sound field composed of multiple sound sources, and the characteristics of the sound sources evolve with the development of engine technology. With the widespread application of high-bypass-ratio turbofan engines, jet noise has been significantly reduced, while fan noise has increased significantly, becoming the main noise source of modern aero-engines. However, in the design of ultra-high-bypass-ratio engines, the short-cabin length is continuously reduced to reduce weight and flight resistance, resulting in a decrease in the ratio of sound lining area to bypass diameter, which severely weakens the noise reduction capability of the engine. In addition, low-frequency noise has the characteristics of long propagation distance and slow attenuation, which not only affects the environmental noise level, but also may excite aircraft structure vibration, causing fatigue damage and even catastrophic failure, so low-frequency noise control has become a major challenge in the field of aero-acoustics.

[0003] Currently, honeycomb micro-perforated panel sound lining structures are widely used in aero-engines for noise suppression. The structure is composed of a perforated panel and a honeycomb core, and its sound absorption mechanism is mainly based on the Helmholtz resonance principle: when the frequency of the sound wave matches the resonance frequency of the honeycomb cell, the viscous friction effect of air in the hole neck can efficiently dissipate sound energy. However, the sound absorption frequency band of the traditional sound lining is severely dependent on the geometric parameters of the honeycomb cell (such as hole diameter and cavity depth), and the resonance frequency is usually in the medium-high frequency range. The resonance frequency of the traditional sound lining structure is difficult to match with low-frequency sound waves with longer wavelengths, and the control effect on low-frequency noise is limited. Although increasing the depth of the honeycomb cavity can lower the resonance frequency of the structure, due to the space limitation of the short cabin, the traditional structure is difficult to achieve low-frequency broadband sound absorption within a limited thickness.

[0004] In recent years, acoustic metamaterials have provided a new approach to breaking through the frequency band limitation of traditional sound lining. Among them, the triply periodic minimal surface (TPMS) structure, as a new type of topological optimization configuration, has the characteristics of continuous smooth surface and developed pore structure. Its unique hole connectivity and multi-scale topological design can precisely control the sound wave propagation path, which is expected to enhance the low-frequency sound absorption efficiency and widen the effective frequency band within a limited space, while maintaining good mechanical properties of the overall structure. SUMMARY

[0005] To solve the above technical problems, the application designs an aero-engine sound lining structure based on a multi-form triply periodic minimal surface and a construction method, which connects different types of TPMS through

[0006] The sigmoid function gradual connection is connected into a multi-form TPMS acoustic metamaterial structure, which is used to replace the honeycomb core layer as the sandwich layer of the engine acoustic liner, and the control ability of the acoustic liner structure on low-frequency noise is enhanced.

[0007] The aero-engine acoustic liner structure based on the multi-form three-period minimal surface of the application comprises a micro-perforated plate, a multi-form TPMS core layer is fixedly connected below the micro-perforated plate, the multi-form TPMS core layer comprises P-type TPMS cells and I-WP type TPMS cells, the P-type TPMS cells and the I-WP type cells are connected into a whole through sigmoid function gradual connection, and a rigid panel is fixedly connected to the lower end of the multi-form TPMS core layer.

[0008] The micro-perforated plate is provided with regularly distributed circular holes, and the perforation rate is 4%.

[0009] The application further provides a construction method of the aero-engine acoustic liner structure, comprising the following steps:

[0010] S1, constructing P-type TPMS cells and I-WP type TPMS cells:

[0011] The P-type TPMS cells are constructed in Mathematica through the following level set approximation equation:

[0012] P (x,y,z)cos(2x / l)cos(2y / l)cos(2z / l)C;

[0013] The I-WP type TPMS cells are constructed in Mathematica through the following level set approximation equation:

[0014] IWP (x,y,z)sin(2x / l)sin(2y / l)sin(2z / l)sin(2x / l)cos(2y / l)cos(2z / l)

[0015] sin(2y / l)cos(2x / l)cos(2z / l)sin(2z / l)cos(2x / l)cos(2y / l)C

[0016] Wherein x, y and z represent spatial coordinates, l represents the size of a single TPMS cell, different sizes of TPMS structures can be obtained by changing the value of l; C is a constant for controlling the topological structure of the TPMS cell surface, represents the volume fraction φ of the TPMS cell structure, and different volume fractions φ of the TPMS model can be obtained by changing the value of the constant C;

[0017] S2, the P-type TPMS cell and the I-WP type TPMS cell are connected together through a connection function to build a multi-morphology TPMS core layer; the multi-morphology TPMS core layer structure is described in Mathematica through the following continuous function:

[0018] PIWP (x,y,z) P (x,y,z)(1) IWP (x,y,z)

[0019] Wherein P (x,y,z) and IWP (x,y,z) respectively represent the P-type and I-WP type TPMS cell, PIWP (x,y,z) represents the multi-morphology TPMS core layer, and beta represents a space weighting function, the value range of which is 0<=beta<=1, and the space weighting function (x,y,z) can be described through the following sigmoid function:

[0020]

[0021] Wherein G(x,y,z) represents a transition boundary function at the fusion stage between the P and I-WP two TPMS structure regions, is used for controlling the transition boundary of the two TPMS substructures intersecting to constitute the multi-morphology TPMS core layer, and parameter K represents the transition width between the two TPMS types;

[0022] S3, the micro-perforated plate is fixedly connected at the top end of the multi-morphology TPMS core layer, and the rigid panel is fixedly connected at the lower end of the multi-morphology TPMS core layer, so as to constitute an aero-engine sound lining structure.

[0023] The parameter K in the S2 is 1.

[0024] Compared with the prior art, the beneficial effects of the present application are:

[0025] (1) the present application has excellent low-frequency sound absorption performance, the sound absorption bandwidth ratio reaches 41.67% (sound absorption coefficient > 0.5) in the low-frequency range of 100-400Hz, the sound absorption coefficient peak value at the resonance frequency of 240Hz reaches 0.9523, which approaches perfect sound absorption, and the thickness of the structure is only 1 / 23 of the wavelength at the resonance frequency, the large wavelength is controlled through the small size structure, and the deep subwavelength characteristics of the structure are embodied.

[0026] (2) the multi-morphology TPMS core layer structure has strong controllable performance, different sizes and different void distributions of the structure can be obtained by adjusting the TPMS cell parameters in the design of the structure parameters, and the structure has developed pores, which meets the lightweight requirement.

[0027] (3) In terms of mechanical properties, the multi-morphology TPMS structure presents a double-platform stress response characteristic, and absorbs a large amount of energy in the stress platform stage, and has good compression performance and energy absorption capacity. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the embodiment description are briefly introduced as follows.

[0029] Figure 1 It is a three-dimensional schematic view of the multi-morphology TPMS core layer structure in the embodiment.

[0030] Figure 2 It is a structure schematic view of the P-type TPMS cell and the I-WP type TPMS cell in the embodiment, wherein A is the P-type TPMS cell, and B is the I-WP type TPMS cell.

[0031] Figure 3 It is a Sigmoid function schematic view of the multi-morphology TPMS core layer transition region under different parameters K in the embodiment.

[0032] Figure 4 It is a sound absorption coefficient schematic view of the multi-morphology TPMS core layer structure in the embodiment within 100-400Hz.

[0033] Figure 5 It is a stress-strain schematic view of the multi-morphology TPMS core layer structure under quasi-static compression in the embodiment.

[0034] Figure 6 It is a specific energy absorption schematic view of the multi-morphology TPMS core layer structure in the embodiment.

[0035] In the drawings, the structure names represented by each number are as follows:

[0036] 1-micro-perforated panel, 2-circular hole, 3-P-type TPMS cell, 4-I-WP type TPMS cell, 5-multi-morphology TPMS core layer, 6-rigid panel. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described clearly and completely in the embodiments of the present application in combination with the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments.

[0038] Embodiment 1

[0039] Referring to Figure 1 The aviation engine sound lining structure based on the multi-morphology three-period minimal surface in the embodiment includes a micro-perforated panel 1, a multi-morphology TPMS core layer 5 is fixedly connected below the micro-perforated panel 1, and the multi-morphology TPMS core layer 5 includes a P-type TPMS cell 3 and an I-WP type TPMS cell 4. Figure 2The P-type TPMS cell 3 and the I-WP-type TPMS cell 4 are connected by a Sigmoid function to form a whole, and the multi-morphology TPMS core layer 5 is fixedly connected with the rigid panel 6 at the lower end.

[0040] The micro-perforated plate 1 has a length of 100 mm, a width of 100 mm, and a height of 1 mm. The micro-perforated plate 1 is provided with regularly distributed circular holes 2. The perforation rate of the micro-perforated plate 1 is 4%, and the diameter d of the circular holes 2 is 1 mm.

[0041] The P-type TPMS cell 3 is established in Mathematica by the following level set approximation equation:

[0042] P (x,y,z)cos(2x / l)cos(2y / l)cos(2z / l)C;

[0043] The I-WP-type TPMS cell 4 is established in Mathematica by the following level set approximation equation:

[0044] IWP (x,y,z)sin(2x / l)sin(2y / l)sin(2z / l)sin(2x / l)cos(2y / l)cos(2z / l)

[0045] sin(2y / l)cos(2x / l)cos(2z / l)sin(2z / l)cos(2x / l)cos(2y / l)C

[0046] Wherein x, y, and z represent spatial coordinates, l represents the size of a single TPMS cell, changing the value of l can obtain TPMS structures of different sizes; C is a constant for controlling the topological structure of the TPMS cell surface, representing the volume fraction φ of the TPMS cell structure, changing the value of the constant C can obtain TPMS models of different volume fractions φ, and when C=0, a shell-shaped TPMS structure can be obtained.

[0047] The size of the P-type TPMS cell 3 is l=10 mm, and the cell volume fraction φ is 20%. The size of the I-WP-type TPMS cell 4 is l=10 mm, and the cell volume fraction φ is 20%.

[0048] The P-type TPMS cell 3 and the I-WP-type TPMS cell 4 are connected together by a connection function to construct the multi-morphology TPMS core layer 5; the structure of the multi-morphology TPMS core layer 5 is described in Mathematica by the following continuous function:

[0049] PIWP (x,y,z) P (x,y,z)(1)IWP (x,y,z)

[0050] wherein P (x,y,z) and IWP (x,y,z) represent P-type and I-WP-type TPMS cells 4, respectively, PIWP (x,y,z) represents P-I-WP multi-morphology TPMS core layer 5, and β represents a spatial weighting function, whose value range is 0≤β≤1, which can be described by the following sigmoid function:

[0051]

[0052] wherein G(x,y,z) represents a transition boundary function between P and I-WP TPMS structure regions in the fusion stage, which is used to control the transition boundary of the intersection of the two TPMS substructures constituting the multi-morphology TPMS core layer 5, and parameter K represents the transition width between the two TPMS types.

[0053] The Sigmoid function diagram of the transition region of the fusion of the P-type TPMS cell 3 and the I-WP-type TPMS cell 4 with different parameters K is shown in Figure 3 The greater the value of parameter K, the narrower the transition region between the two substructures, and the more prominent the transition of the two substructures of the P-type TPMS cell 3 and the I-WP-type TPMS cell 4 after fusion, and the structural stress concentration increases. In order to reduce the structural stress concentration, parameter K=1 is selected.

[0054] In this embodiment, the size of the P-type TPMS cell 3 and the I-WP-type TPMS cell 4 is l=10 mm, and the height of the multi-morphology TPMS core layer 5 is 60 mm. The length, width and height of the rigid panel 6 are all 100 mm.

[0055] As shown in Figure 4 , the multi-morphology TPMS core layer 5 is used instead of the traditional honeycomb as the sandwich layer of the sound insulation structure, and the structure shows excellent sound absorption performance in the low frequency range of 100-400 Hz. The peak value of the sound absorption coefficient at the resonance frequency of 240 Hz reaches 0.9523, and the sound absorption coefficient of the structure in the frequency range of 185-310 Hz is all above 0.5, and the absorption bandwidth ratio is 41.67%, which effectively absorbs noise in a wide low frequency range.

[0056] The total thickness of the multi-morphology TPMS core layer 5 structure is only 62 mm, which is only 1 / 23 of the wavelength corresponding to the resonance frequency of the structure, which reflects the deep subwavelength characteristics of the structure.

[0057] As shown in Figure 5 , when the multi-morphology TPMS core layer 5 is used as the sandwich layer, the structure shows a double-platform stress characteristic under quasi-static compression.

[0058] Under quasi-static compression, the substructure P type TPMS cell 3 of the multi-morphology TPMS core layer 5 deforms first as the applied load increases. Under the action of stress, the P type TPMS cell 3 gradually approaches to be dense, and the I-WP type TPMS cell 4 deforms subsequently as the applied load gradually increases. That is, the multi-morphology TPMS core layer 5 deforms in layers.

[0059] As shown in Figure 6 The structural energy absorption curve is divided into two stages at about 0.45 strain, the structure absorbs less energy before 0.45 strain, and the energy absorption performance of the structure improves sharply after 0.45 strain, the energy absorption performance of the structure is slow first and then fast. The specific energy absorption of the structure is close to 35 KJ / Kg after the strain reaches 0.75, which shows excellent energy absorption performance.

[0060] The preferred embodiments disclosed above are only used to help illustrate the present application. The preferred embodiments do not describe all the details, and the application is not limited to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of the present application.

Claims

1. Aeroengine acoustic liner structure based on a multi-modal three-period minimal surface, characterized in that, Micro-perforated panel (1) is fixedly connected with multi-form TPMS core layer (5) below, the multi-form TPMS core layer (5) includes P-type TPMS cell (3) and I-WP type TPMS cell (4), the P-type TPMS cell (3) and the I-WP type TPMS cell (4) are connected as a whole by Sigmoid function gradual change, and the multi-form TPMS core layer (5) is fixedly connected with rigid panel (6) at the lower end.

2. The aeroengine acoustic liner structure based on a multi-modal three-periodic minimal surface of claim 1, wherein, Regularly distributed circular holes (2) are formed in the micro-perforated panel (1), and the perforation rate is 4%.

3. The method of constructing an acoustic lining structure for an aeroengine according to any one of claims 1-2, wherein, The method comprises the following steps: S1, constructing P-type TPMS cell (3) and I-WP type TPMS cell (4): The P-type TPMS cell (3) is established in Mathematica by the following level set approximation equation: P (x, y, z) cos (2x / l) cos (2y / l) cos (2z / l) C; The I-WP type TPMS cell (4) is established in Mathematica by the following level set approximation equation: I WP (x, y, z) sin (2x / l) sin (2y / l) sin (2z / l) sin (2x / l) cos (2y / l) cos (2z / l) sin (2y / l) cos (2x / l) cos (2z / l) sin (2z / l) cos (2x / l) cos (2y / l) C Where x, y, z represent spatial coordinates, l represents the size of a single TPMS cell, and different sizes of TPMS structures can be obtained by changing the value of l;C is a constant for controlling the surface topological structure of the TPMS cell, which represents the volume fraction φ of the TPMS cell structure, and different volume fractions φ of the TPMS model can be obtained by changing the value of the constant C; S2, the P-type TPMS cell (3) and the I-WP type TPMS cell (4) are connected together to construct the multi-form TPMS core layer (5) by the connecting function;The structure of the multi-form TPMS core layer (5) is described in Mathematica by the following continuous function: PIWP (x,y,z) P (x,y,z)(1) IWP (x,y,z) wherein P (x,y,z) and IWP (x,y,z) represent the P-type and I-WP-type TPMS cells (4), respectively, PIWP (x,y,z) represents the polymorphic TPMS core layer (5), and β represents a spatial weighting function with a value range of 0≤β≤1, which can be described by the following sigmoid function: Where G (x, y, z) represents the transition boundary function of the fusion stage between the P and I-WP two TPMS structure regions, which is used to control the transition boundary of the intersection of the two TPMS substructures constituting the multi-form TPMS core layer (5), and the parameter K represents the transition width between the two TPMS types; S3, the micro-perforated panel (1) is fixedly connected with the multi-form TPMS core layer (5) at the top end, and the multi-form TPMS core layer (5) is fixedly connected with the rigid panel (6) at the lower end, so as to form an aero-engine sound lining structure.

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