A porous wave leading edge bionic combined configuration blade

Abstract

The present invention discloses a porous wave leading edge bionic combination configuration blade, which belongs to the turbulent broadband noise control of aviation turbines. The blade is based on the innovative idea of "wave leading edge" coupled with "porous medium". First, the wave leading edge blade is designed, and secondly, the porous medium material is coupled on the basis of the wave leading edge. Compared with the "single" wave leading edge configuration and the "single" porous medium configuration, the innovative bionic combination configuration proposed in the present invention can significantly improve the noise reduction level of the bionic configuration. Whether from the sound pressure level spectrum or from the total sound pressure level directivity, the beneficial effect of the innovative "wave leading edge" coupled with "porous medium" bionic combination configuration proposed in the present invention is that it can significantly improve the noise reduction level of the bionic configuration, and it is a passive noise control solution with great noise reduction potential.

Description

1. Technical Field

[0001] The technical field to which the present invention belongs is the control of turbulent broadband noise of aviation turbines. 2. Background Technology

[0002] As engine bypass ratios gradually increase, the broadband turbulent noise of aircraft turbine fans has become increasingly prominent, becoming a technical bottleneck and a key scientific challenge in further reducing aircraft noise. The bionic flow noise control theory, which "learns from nature," offers a new breakthrough in reducing fan noise. Current bionic noise control theories draw inspiration from two main sources: the "super-quiet" flight of owls and the "super-maneuverable" movement of humpback whales.

[0003] To mimic the structural characteristics of the "super-quiet" flying owl's wings, a "porous medium" biomimetic noise reduction configuration has been proposed. To mimic the structural characteristics of the "super-maneuverable" humpback whale's flippers, a "wave leading edge" biomimetic noise reduction configuration has been proposed. Through extensive scientific research by numerous scholars, both porous media and wave leading edges have been proven to be effective noise control methods. However, both porous media and wave leading edges have certain drawbacks. For example, porous media can significantly increase high-frequency noise, while the "trough" of the wave leading edge still presents a very strong noise source, severely limiting the noise reduction potential of biomimetic configurations. The fundamental reason for this is that current research has exclusively used a "single" porous medium or "single" wave leading edge configuration. To address the scientific and technological challenges currently existing in biomimetic noise reduction research, this paper proposes an innovative biomimetic configuration combining a "wave leading edge" with a "porous medium," aiming to significantly improve the noise reduction capabilities of this biomimetic configuration.

[0004] Among the patents that have been applied for, those involving the wavy leading edge of the blade include "A method for constructing the wavy leading edge of a low-pressure turbine stator blade" (application number: CN202110064795.2), "A method for designing a blade with a wavy leading edge and a serrated trailing edge" (application number: CN201911068586.4), "A bionic hypocycloid wavy leading edge blade and design method" (application number: 202210557354.0), and "A bionic elliptical wavy leading edge blade and design method" (application number: 202111362884.1). The above patents mainly use a "single" wavy leading edge, while the innovation of this invention lies in the use of a new bionic combination configuration of "wavy leading edge" coupled with "porous medium". 3. Summary of the Invention

[0005] The purpose of the present invention is to provide a porous wave leading edge bionic combined configuration blade, based on the innovative idea of "wave leading edge" coupling "porous medium", firstly designing the wave leading edge blade, and then coupling the porous medium material on the basis of the wave leading edge.

[0006] The technical solution of the present invention is: a porous wave leading edge bionic combined configuration blade, characterized in that the blade configuration is a wave leading edge blade, the leading edge portion of the wave leading edge blade 10% to 30% of the chord length is made of porous medium material, refer to Figure 8 ;

[0007] The conventional wavy leading edge blade configuration is generated based on a two-dimensional reference blade profile, see Figure 2 , the two-dimensional reference blade leading edge point O, chord length c, maximum thickness d and maximum thickness position P;

[0008] See Figure 3 The blade generates a wavy leading edge line based on the two-dimensional reference blade profile according to the following cosine function:

[0009]

[0010] The wavy cosine line mainly has two characteristic parameters: amplitude A and wavelength W. It includes three characteristic sections: crest, mid-wave and trough. The mid-wave section is the same as the reference blade profile, and z is the spanwise coordinate.

[0011] According to the cosine line, the variation law of the chord length of the wavy blade along the span direction is determined as follows:

[0012]

[0013] Based on the local chord length at different spanwise positions, the reference blade profile is stretched or compressed according to the following formula:

[0014]

[0015] Among them, x old ,y old , x new ,y new are the reference blade coordinates and the new coordinates after stretching or compressing, respectively. max The horizontal coordinate corresponding to the maximum thickness position is shown in Figure 2. The three characteristic cross-section diagrams of the peak, middle and trough are shown in Figure 2. Figure 5 As shown;

[0016] The blade profile at the current span direction is stacked spanwise to obtain a conventional wavy leading edge blade as shown in the following figure: Figure 6 shown.

[0017] The beneficial effect of the present invention is that it combines the design concepts of conventional wave leading edge blades and conventional porous medium blades, adopts the strategy of "wave leading edge" coupled with "porous medium", and finally generates a new porous wave leading edge bionic combination configuration blade. Compared with the "single" wave leading edge configuration and the "single" porous medium configuration, the innovative bionic combination configuration proposed by the present invention can significantly improve the noise reduction level of the bionic configuration, such as Figure 1 As shown. Figure 1 From the sound pressure level spectrum of (a), it can be seen that the "single" wave leading edge configuration can significantly reduce broadband noise, but its ability to reduce single-tone noise is limited; the "single" porous medium configuration can significantly reduce single-tone noise, but its ability to reduce broadband noise is limited. However, the bionic combination configuration proposed in the present invention takes into account the advantages of the two "single" bionic configurations, and can effectively reduce both single-tone noise and broadband noise, greatly expanding the noise reduction frequency band and noise reduction amount of the bionic configuration. Figure 1 As shown in the total sound pressure level directivity of (b), the bionic combination configuration improves noise reduction at all azimuth angles. For example, at an azimuth angle of 90°, the wave leading edge reduces noise by 4.4 dB, the porous medium reduces noise by 8.8 dB, and the porous wave leading edge bionic combination configuration reduces noise by 11.5 dB. Whether viewed from the sound pressure level spectrum or the total sound pressure level directivity, the innovative "wave leading edge" coupled with "porous medium" bionic combination configuration proposed in this invention significantly improves the noise reduction level of the bionic configuration, making it a passive noise control solution with great noise reduction potential. 4. Description of the Figures

[0018] Figure 1 Beneficial effects of the porous wave leading edge bionic combination configuration proposed in the present invention: (a) analysis of the noise reduction effect of sound pressure level; (b) analysis of the noise reduction effect of total sound pressure level.

[0019] Figure 2 Schematic diagram of the reference blade and reference blade profile: (a) front view of the reference straight blade; (b) two-dimensional reference blade profile.

[0020] Figure 3 Schematic diagram of the leading edge line of a wavy leading edge blade.

[0021] Figure 4 Verification of the smoothness of sinusoidal lines generated by different numbers of sections in a single cycle.

[0022] Figure 5 Schematic diagram of the two-dimensional cross-section profile of a wavy leading edge blade.

[0023] Figure 6 Schematic diagram of a conventional wavy leading edge blade.

[0024] Figure 7 Schematic diagram of a conventional porous media blade.

[0025] Figure 8 Schematic diagram of the new porous wavy leading edge bionic combined configuration blade. 5. Specific Implementation Methods

[0026] In this embodiment, the porous wave leading edge bionic combined configuration blade has a conventional wave leading edge blade, and the leading edge portion of the conventional wave leading edge blade having a 30% chord length is made of a porous medium material. Figure 8 In this embodiment, the material used for the leading edge portion is a porous medium material with a porosity of 0.95 and a chord-wise length of 30% of the chord length.

[0027] The process of determining the conventional wavy leading edge configuration blade in this embodiment is as follows:

[0028] (1) Determine the leading edge point O, chord length c, maximum thickness d, and the position P of the maximum thickness of the two-dimensional reference blade profile, as follows: Figure 2 In this embodiment, the chord length c is 150 mm and the maximum thickness d is 18 mm.

[0029] (2) Generate a wavy leading edge line based on the following cosine function, such as Figure 3 shown.

[0030]

[0031] The wavy cosine line mainly has two characteristic parameters: amplitude A and wavelength W, including three characteristic sections: crest, middle and trough. The middle section is the same as the reference blade profile, and z is the spanwise coordinate.

[0032] In the design of wavy leading edge blades, the number of sections N in a single cycle is an important factor affecting the smoothness of the leading edge line. The present invention first studies this, such as Figure 4 As shown, the number of sections within a single cycle is N = 5, 9, 17, 33, and 1025, respectively. A larger N yields a smoother curve, but the generation process takes longer. Comparative analysis shows that N = 33 ensures sufficient smoothness. Therefore, for the wavy leading edge design, considering both curve smoothness and generation efficiency, N = 33 is chosen in this embodiment.

[0033] (3) Based on the cosine line determined in the previous step, the variation law of the chord length of the wavy blade along the span direction is determined as follows.

[0034]

[0035] Based on the local chord length at different spanwise positions, the reference blade profile is stretched or compressed according to the following formula.

[0036]

[0037] Among them, xold ,y old , x new ,y new are the reference blade coordinates and the new coordinates after stretching or compressing, respectively. max The horizontal coordinate corresponding to the maximum thickness position is shown in the following figure: Figure 5 shown.

[0038] (4) According to the conclusion obtained in the second step, a single-cycle wave leading edge blade can be generated by using 33 sections in one cycle. By stacking all the sections (the total number of spanwise sections is determined by the spanwise direction of the blade), a conventional wave leading edge blade can be obtained, such as Figure 6 shown.

[0039] (5) Based on the mechanism of porous media controlling turbulence-leading edge interference noise, filling the leading edge of the blade with porous media materials can effectively control the leading edge noise. Conventional porous media blades such as Figure 7 shown.

[0040] (6) Combining the design ideas of conventional wave leading edge blades and conventional porous medium blades, the “wave leading edge” coupled with “porous medium” strategy can generate the final new porous wave leading edge bionic combined configuration blade, such as Figure 8 According to the incoming flow conditions, the noise reduction level of the porous wave leading edge bionic combination configuration can be significantly improved by comprehensively adjusting the structural parameters of the porous wave leading edge bionic combination configuration blade, such as amplitude, wave, porous medium flow length, porous medium porosity, etc.

[0041] like Figure 1 As shown in FIG, the sound pressure level spectrum and the total sound pressure level directivity of the reference blade, wave leading edge blade, porous medium blade and porous wave leading edge bionic combination blade in this embodiment are given. Figure 1 (a) It can be seen that within the range of 1000Hz to 4000Hz, the wave leading edge blade can effectively reduce noise, but its ability to reduce single-tone noise within 500Hz to 600Hz is limited; within 1000Hz to 4000Hz, the porous medium blade has limited noise reduction, but its ability to reduce single-tone noise within 500Hz to 600Hz is relatively strong; for the "wave leading edge" coupled "porous medium" bionic combination configuration proposed in the present invention, it can effectively reduce single-tone noise within 500Hz to 600Hz, and can also effectively reduce broadband noise within 1000Hz to 4000Hz. Figure 1(b) It can be seen that the novel bionic combination configuration proposed in this invention significantly improves noise reduction capabilities at all azimuth angles, combining the noise reduction advantages of two single bionic configurations. This example clearly demonstrates that the novel "wave leading edge" coupled with "porous medium" porous wave leading edge bionic combination blade configuration proposed in this invention significantly improves noise reduction, demonstrating its potential as a bionic configuration with enormous noise reduction potential.

Claims

1. A porous wave leading edge bionic combined configuration blade, characterized in that: The blade configuration is a wavy leading edge blade, and the material of the leading edge portion of 10% to 30% of the chord length of the wavy leading edge blade is a porous medium material; The conventional wavy leading edge blade configuration is generated based on a two-dimensional reference blade profile, including a leading edge point O, a chord length c, a maximum thickness d, and a position P where the maximum thickness is located. The blade generates a wavy leading edge line based on the two-dimensional reference blade profile according to the following cosine function: The wavy cosine line mainly has two characteristic parameters: amplitude A and wavelength W. It includes three characteristic sections: crest, mid-wave and trough. The mid-wave section is the same as the reference blade profile, and z is the spanwise coordinate. According to the cosine line, the variation law of the chord length of the wavy blade along the span direction is determined as follows: Based on the local chord length at different spanwise positions, the reference blade profile is stretched or compressed according to the following formula: Among them, xold, yold, xnew, and ynew are the reference blade profile coordinates and the new coordinates after stretching or compression operations, respectively, and xmax represents the horizontal coordinate corresponding to the maximum thickness position.

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