A rudder with an attached acoustic black hole

Abstract

The present invention discloses a rudder with an attached acoustic black hole, relating to the field of aerospace technology. The rudder comprises a rudder body and an acoustic black hole structure. The rudder body is provided with a cavity, a base is provided within the rudder body, and the acoustic black hole structure is located in the cavity and mounted on the base. The acoustic black hole structure and the base are detachably connected. Based on the wave energy concentration effect and dynamic vibration absorption principle of the acoustic black hole, the present invention, by providing the acoustic black hole structure, can reduce the flutter amplitude of the rudder to a certain extent, thereby improving the flutter Mach number, flutter critical speed, and flutter pressure of the rudder.

Description

Technical Field

[0001] The present invention relates to the field of aerospace technology, in particular to a rudder with an attached acoustic black hole. Background Art

[0002] Flutter refers to the self-excited vibration of an elastic body, with increasing amplitude, caused by the interaction of aerodynamic, inertial, and elastic forces. Flutter suppression primarily involves delaying, suppressing, or even preventing this increasing amplitude through vibration control. Existing flutter suppression methods are primarily categorized into active flutter suppression and passive flutter suppression. Active flutter suppression involves three steps: first, sensors acquire the vibration response signals of the wing structure; second, a control system outputs control commands based on the input vibration response signals; and third, these control commands drive the deflection of the wing control surfaces to adjust the flow field distribution around the wing, thereby suppressing wing flutter. Passive flutter suppression is simpler than active flutter suppression. Common methods involve modifying the wing structure and material properties, optimizing the mass counterweight, and increasing the natural frequency of the wing's coupled modes, thereby raising the critical flutter speed of the wing.

[0003] The existing active flutter suppression control process is complex and still has a certain distance from practical application, while most passive flutter suppression may increase wing mass and increase flight costs. Summary of the Invention

[0004] The purpose of the present invention is to provide a rudder with an attached acoustic black hole, which solves the problem of rudder flutter suppression by utilizing the principle of dynamic vibration absorber and acoustic black hole effect.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a rudder with an attached acoustic black hole, comprising a rudder body and an acoustic black hole structure. A cavity is provided inside the rudder body, a base is provided inside the rudder body, the acoustic black hole structure is located in the cavity and is arranged on the base, and the acoustic black hole structure and the base are detachably connected.

[0007] Preferably, the acoustic black hole structure includes one or two acoustic black hole components.

[0008] Preferably, the acoustic black hole assembly includes a damping plate and an acoustic black hole, one end of the damping plate is connected to one end of the acoustic black hole, and the acoustic black hole is provided with a connecting hole, which is eccentrically arranged.

[0009] Preferably, both ends of the damping plate and both ends of the acoustic black hole are planes, one end of the damping plate is connected to the large end of the acoustic black hole, the outer contour size of the large end of the acoustic black hole is the same as the outer contour size of the damping plate, the outer contour size of the small end of the acoustic black hole is smaller than the outer contour size of the large end of the acoustic black hole, and there is a curved surface structure between the small end of the acoustic black hole and the large end of the acoustic black hole, and the thickness of the curved surface structure varies in the form of a power exponent.

[0010] Preferably, the damping plate is annular, and the first through hole of the damping plate is connected to the connecting hole.

[0011] Preferably, when the acoustic black hole structure includes two acoustic black hole components, the small end of the acoustic black hole of one acoustic black hole structure passes through the damping plate of the other acoustic black hole structure and is connected to the large end of the acoustic black hole of the other acoustic black hole structure, and the connecting holes of the two acoustic black holes are concentrically arranged.

[0012] Preferably, an annular gasket is provided between the small end of the acoustic black hole of one acoustic black hole structure and the large end of the acoustic black hole of another acoustic black hole structure, and the annular gasket is provided with a second through hole, and the second through hole is concentrically arranged with the connecting hole of each acoustic black hole.

[0013] Preferably, both ends of the damping plate and both ends of the acoustic black hole are planes, one end of the damping plate is connected to the large end of the acoustic black hole, and there is a curved surface structure between the small end of the acoustic black hole and the large end of the acoustic black hole, and the thickness of the curved surface structure varies in the form of a power exponent.

[0014] Preferably, the projection of the acoustic black hole on a plane perpendicular to the axis of the connecting hole is fan-shaped, the projection of the damping plate on a plane perpendicular to the axis of the connecting hole is arc-shaped, the damping plate includes an inner arc edge and an outer arc edge, the inner arc edge is located on the inner side of the outer arc edge, the outer arc edge has the same size as the arc edge of the acoustic black hole, and the outer arc edge coincides with the projection of the arc edge on a plane perpendicular to the axis of the connecting hole.

[0015] Compared with the prior art, the present invention has achieved the following technical effects:

[0016] Based on the wave energy gathering effect and dynamic vibration absorption principle of the acoustic black hole, the present invention can reduce the flutter amplitude of the rudder to a certain extent by setting an acoustic black hole structure, and improve the flutter Mach number, flutter critical speed and flutter pressure of the rudder. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 is a schematic diagram of a rudder body of the present invention;

[0019] Figure 2 for Figure 1 AA section view;

[0020] Figure 3 for Figure 2 A partial enlarged view of FIG;

[0021] Figure 4 for Figure 1 BB cross-sectional view;

[0022] Figure 5 for Figure 1 Bottom view of

[0023] Figure 6 for Figure 5 A partial enlarged view of

[0024] Figure 7 Schematic diagram of the acoustic black hole structure of the present invention (Example 1);

[0025] Figure 8 for Figure 7 CC sectional view (Example 1);

[0026] Figure 9 for Figure 7 DD sectional view (Example 1);

[0027] Figure 10 Schematic diagram of the acoustic black hole structure of the present invention (Example 2);

[0028] Figure 11 for Figure 10 EE cross-sectional view (Example 1);

[0029] Figure 12 for Figure 10 FF cross-sectional view (Example 1);

[0030] Figure 13 Schematic diagram of the acoustic black hole structure of the present invention (Example 3);

[0031] Figure 14 for Figure 13 GG cross-sectional view (Example 1);

[0032] Figure 15 for Figure 13 HH sectional view (Example 1);

[0033] Figure 16 is a schematic diagram of the mass block;

[0034] Figure 17 is a schematic diagram of a disk of equal mass;

[0035] Figure 18 for Figure 17 II sectional view;

[0036] Figure 19 for Figure 17 JJ sectional view;

[0037] Figure 20 Schematic diagram of a rudder with an attached acoustic black hole according to the present invention (including the acoustic black hole structure in Example 1);

[0038] Figure 21 Schematic diagram of a rudder with an attached acoustic black hole according to the present invention (including the acoustic black hole structure in Example 2);

[0039] Figure 22 Schematic diagram of a rudder with an attached acoustic black hole according to the present invention (including the acoustic black hole structure in Example 3);

[0040] Figure 23 This is a schematic diagram of the installation of the mass block and the rudder body;

[0041] Figure 24 This is a schematic diagram of the installation of the equal-mass disk and the rudder body;

[0042] Figure 25 is the critical response curve of flutter displacement of the rudder with mass block and the rudder with equal mass disk;

[0043] Figure 26 The graphs are critical flutter response curves of a rudder with an equal-mass disk and a rudder with an attached acoustic black hole according to Example 1;

[0044] Figure 27 The flutter critical displacement response curves of the equal-mass disk (dashed line) and the rudder body containing the equal-mass disk (solid line) under the air flow of 2.20 Ma;

[0045] Figure 28 The critical flutter displacement response curves of the attached acoustic black hole (dashed line) and the rudder with the attached acoustic black hole (solid line) under the air flow of 2.35 Ma;

[0046] Among them: 1-rudder body, 2-cavity, 3-base, 4-wingtip surface, 5-wing root surface, 6-axis of rudder shaft, 7-boundary condition area, 8-damping plate, 9-acoustic black hole, 10-connecting hole, 11-first through hole, 12-gasket, 13-mass block, 14-equal mass disk structure, 15-annular damping plate, 16-disc. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] The purpose of the present invention is to provide a rudder with an attached acoustic black hole, which solves the problem of rudder flutter suppression by utilizing the principle of dynamic vibration absorber and acoustic black hole effect.

[0049] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] Example 1

[0051] The acoustic black hole effect utilizes changes in the structural impedance to alter the phase and group velocity of waves propagating through the structure, thereby converging the waves in specific areas of the structure. If the cross-sectional thickness of the structure is reduced exponentially to the minimum machinable value, the shear wave vibration amplitude will gradually increase as it propagates to the tip of the variable thickness section. The damping material affixed to the tip of the structure effectively dissipates the vibration energy.

[0052] like Figures 1 to 9 As shown: This embodiment provides a rudder with an attached acoustic black hole, including a rudder body 1 and an acoustic black hole structure. A cavity 2 is provided inside the rudder body 1, a base 3 is provided inside the rudder body 1, and the base 3 is provided with holes. The acoustic black hole structure is located in the cavity 2 and is arranged on the base 3. The acoustic black hole structure does not contact the inner wall of the rudder body 1, and the acoustic black hole structure and the base 3 are detachably connected by bolts. The position of the base 3 changes with the installation position of the acoustic black hole structure, but different installation positions of the acoustic black hole structure have completely different effects on the flutter of the rudder body 1. The best installation position of the base 3 is at the rightmost position of the rudder body 1 close to the wingtip surface 4 (with Figure 1(The perspective is used as the basis). At this time, the vibration displacement amplitude of the base 3 is large, achieving the best dynamic vibration absorption effect. The rudder body 1 serves as the main structure of the dynamic vibration absorber, and the acoustic black hole structure serves as an additional structure of the dynamic vibration absorber. When the vibration frequency (flutter frequency) caused by the aerodynamic force acting on the main structure equals the natural frequency of the additional structure, the additional structure and the main structure will engage in dynamic vibration absorption. In other words, the rudder body 1 transfers a portion of the vibration energy to the acoustic black hole structure, causing it to vibrate violently and achieve dynamic vibration absorption.

[0053] Specifically, in this embodiment, the rudder body 1 is an improved version of the HD3103B rudder model, the small end of the rudder body 1 is the wingtip surface 4, the large end of the rudder body 1 is the wingroot surface 5, and a rudder shaft is provided in the rudder body 1, and the rudder body 1 rotates around the axis 6 of the rudder shaft.

[0054] In this embodiment, the acoustic black hole structure includes an acoustic black hole 9 component.

[0055] In this embodiment, the acoustic black hole 9 component includes a damping plate 8 and an acoustic black hole 9. One end of the damping plate 8 is connected to one end of the acoustic black hole 9 by glue. The acoustic black hole 9 is provided with a connecting hole 10, and the connecting hole 10 is eccentrically arranged.

[0056] In this embodiment, both ends of the damping plate 8 and the acoustic black hole 9 are flat. One end of the damping plate 8 is connected to the larger end of the acoustic black hole 9. The outer contour dimensions of the larger end of the acoustic black hole 9 are the same as those of the damping plate 8. The outer contour dimensions of the smaller end of the acoustic black hole 9 are smaller than those of the larger end of the acoustic black hole 9. A curved surface structure is formed between the smaller end of the acoustic black hole 9 and the larger end of the acoustic black hole 9. The curved surface structure is an irregular curved surface structure with a certain thickness. The projected distance from a point on the irregular curved surface to the end face of the larger end of the acoustic black hole 9 is the thickness of the irregular curved surface. The thickness direction of the irregular curved surface is parallel to the axis of the connecting hole 10. The thickness of the irregular curved surface varies from the edge of the acoustic black hole 9 to the center of the connecting hole 10 according to a certain power exponent. The curved surface structure possesses the basic characteristics of energy concentration of the acoustic black hole 9.

[0057] In this embodiment, the damping plate 8 is annular and has a certain thickness. The damping plate 8 has a first through hole 11 and a connecting hole 10 .

[0058] Example 2

[0059] like Figures 10 to 12As shown, the difference between this embodiment and embodiment 1 is that: in this embodiment, when the acoustic black hole structure includes two acoustic black hole 9 components, the small end of the acoustic black hole 9 of one acoustic black hole structure passes through the damping plate 8 of the other acoustic black hole structure and is connected to the large end of the acoustic black hole 9 of the other acoustic black hole structure, the connecting holes 10 of the two acoustic black holes 9 are concentrically arranged, and the acoustic black hole 9 of the other acoustic black hole structure is connected to the base 3.

[0060] In this embodiment, an annular gasket 12 is arranged between the small end of the acoustic black hole 9 of one acoustic black hole structure and the large end of the acoustic black hole 9 of another acoustic black hole structure. The annular gasket 12 is provided with a second through hole, and the second through hole is concentrically arranged with the connecting hole 10 of each acoustic black hole 9. The material of the annular gasket 12 is ceramic or other metal material with high hardness, which can not only avoid the mutual contact between the outer edges of the two acoustic black hole structures, but also facilitate the efficient transfer of the vibration energy of the acoustic black hole structure fixed on the rudder body 1 to the other acoustic black hole structure that is not in direct contact with the rudder body 1, so that both structures can absorb the vibration energy well and perform stronger damping consumption.

[0061] Compared with the acoustic black hole structure including one acoustic black hole 9 component in the first embodiment, the acoustic black hole structure including two acoustic black hole 9 components in this embodiment has a better effect on the rudder body 1 (such as Figure 21 (as shown) has a stronger flutter suppression effect. When flutter occurs, the double-layer acoustic black hole structure accumulates and absorbs more energy than a single-layer acoustic black hole structure. As a result, when the rudder body 1 transfers more energy to the double-layer acoustic black hole structure, maintaining the critical flutter state of the rudder body 1 with constant amplitude vibration requires increasing the work done by the aerodynamic force on the rudder body 1, that is, increasing the incoming flow velocity.

[0062] Example 3

[0063] like Figures 13 to 15 As shown, the difference between this embodiment and embodiment 1 is that: in this embodiment, both ends of the damping plate 8 and both ends of the acoustic black hole 9 are planes, one end of the damping plate 8 is connected to the large end of the acoustic black hole 9, and there is a curved surface structure between the small end of the acoustic black hole 9 and the large end of the acoustic black hole 9, and the thickness of the curved surface structure changes in the form of a power exponent.

[0064] In this embodiment, the projection of the acoustic black hole 9 on the plane perpendicular to the axis of the connecting hole 10 is fan-shaped, and the projection of the damping plate 8 on the plane perpendicular to the axis of the connecting hole 10 is arc-shaped. The damping plate 8 includes an inner arc edge and an outer arc edge. The inner arc edge is located on the inner side of the outer arc edge. The outer arc edge has the same size as the arc edge of the acoustic black hole 9, and the projection of the outer arc edge on the plane perpendicular to the axis of the connecting hole 10 coincides with the projection of the arc edge.

[0065] In this embodiment, the acoustic black hole structure is an eccentrically slotted structure, an improvement on the acoustic black hole structure of Example 1. Two straight lines tangent to the circular edge of the small end serve as the cutting path, and these two lines are cut twice at a predetermined angle. This eccentrically slotted acoustic black hole structure can be adjusted in its installation orientation based on the maximum vibration displacement amplitude of the rudder body 1 to find the optimal energy absorption angle.

[0066] for Figure 13 The acoustic black hole structure of the eccentric groove structure shown has different natural frequencies corresponding to different groove angles. By finding a suitable groove angle, the first two natural frequencies of the acoustic black hole structure of the eccentric groove structure are matched with the natural frequency of the flutter of the rudder body 1, which is more conducive to the occurrence of dynamic vibration absorption.

[0067] Compared with the acoustic black hole structure including an acoustic black hole 9 component in the first embodiment, the acoustic black hole structure with an eccentric groove structure in this embodiment has a more efficient flutter suppression effect on the rudder body 1.

[0068] The experimental comparison is as follows:

[0069] The flight environment of the rudder body 1 is a supersonic air flow of 1.5-5 Mach, and the flow direction is from left to right (with Figure 1 The incoming airflow is parallel to the wingtip surface 4 and the wing root surface 5. During the wind tunnel test, the wing root surface 5 is placed vertically downward and the wingtip surface 4 is placed vertically upward to offset the static deformation of the rudder body 1 caused by gravity.

[0070] For ease of analysis during simulation, displacement boundary conditions for the rudder body 1 are set in the center of the wing root surface 5. The boundary condition region 7 primarily consists of a central circular region and two rectangular regions. The circular region is set to a full displacement constraint, essentially keeping it stationary. Displacement constraints are set perpendicular to the wing root surface 5, effectively eliminating displacements perpendicular to the wing root surface 5. These two constraints simulate the fixed connection between the rudder body 1 and the rudder shaft. Using the bidirectional fluid-structure interaction method of ANSYS & Fluent, the critical flutter displacement response of the rudder body 1 containing different acoustic black hole structures under varying incoming flow velocities is determined.

[0071] Control group 1: mass 13

[0072] like Figure 16 As shown, the mass block 13 is a solid cylinder. The material of the mass block 13 can be selected from materials with high density and small volume such as iron, lead, or conventional aluminum alloy materials, as long as the mass block 13 can be normally installed on the base 3 of the rudder body 1.

[0073] like Figure 23As shown, the mass block 13 is installed on the rudder body 1, and then a two-way flow coupling analysis is performed under different incoming flow Mach numbers to obtain the flutter critical response of the rudder body 1 including the mass block 13.

[0074] Control group 2: equal-mass disk structure 14 (mass of mass block 13, equal-mass disk structure 14, and acoustic black hole structure are equal)

[0075] like Figures 17 to 19 As shown, the equal-mass disc structure 14 comprises an annular damping plate 15 and a disc 16. One end of the annular damping plate 15 is glued to the other end of the disc 16. The annular damping plate 15 has a certain thickness and is made of butyl rubber or other alternative materials with a high damping coefficient. The disc 16 has an eccentric circular hole for connection to the base 3. The outer ring of the hole is marked with a circular marking line to guide the assembly of the disc 16 and the base 3.

[0076] like Figure 24 As shown, the equal-mass disk structure 14 is installed on the rudder body 1, and then a two-way flow coupling analysis is performed under different incoming flow Mach numbers to obtain the flutter critical response of the rudder body 1 containing the equal-mass disk 14.

[0077] Experimental Group 1: Acoustic Black Hole Structure includes an Acoustic Black Hole 9 Component

[0078] like Figure 20 As shown, the acoustic black hole structure is installed on the rudder body 1, and then a two-way flow coupling solution analysis is performed under different incoming flow Mach numbers to obtain the flutter critical response of the rudder body 1 containing an acoustic black hole 9 component.

[0079] Figure 25 It represents the critical displacement response of the flutter of the rudder with equal mass block and the rudder with equal mass disk. The flutter Mach number of the rudder with equal mass block is 2.18Ma, and the flutter Mach number of the rudder with mass disk is 2.20Ma, which shows that the equal mass disk has a preliminary flutter suppression effect on the rudder. Figure 26 The figure shows the critical flutter response of the rudder with equal mass blocks and the rudder with an attached acoustic black hole structure in Example 1. The critical flutter Mach number of the rudder with the acoustic black hole structure in Example 1 is 2.35 Ma, which shows that the acoustic black hole structure can further suppress the flutter of the rudder. Figure 25 and Figure 26From the displacement response curve amplitudes, it can be found that the maximum displacement response amplitude of the rudder body 1 with the equal-mass disk 14 is 31.44% lower than that of the rudder body 1 with the equal-mass block 13, and the maximum displacement response amplitude of the rudder body 1 with the acoustic black hole structure is 48.48% lower than that of the rudder body 1 with the equal-mass block 13. This shows that both the equal-mass disk 14 and the acoustic black hole structure can effectively reduce the flutter response amplitude of the rudder body 1, and the acoustic black hole structure has a more obvious effect on reducing the flutter amplitude of the rudder body 1.

[0080] Figure 27 The figure shows the critical flutter displacement responses of the equal-mass disk 14 (dashed line) and the rudder body 1 containing the equal-mass disk (solid line) under an air flow of 2.20 Ma. The average vibration response amplitude of the equal-mass disk 14 and the average vibration response amplitude of the rudder body 1 are approximately equal. Figure 28 The figure shows the critical flutter displacement responses of the attached acoustic black hole (dashed line) and the rudder containing the attached acoustic black hole (solid line) under the air flow of 2.35 Ma. The average vibration response amplitude of the attached acoustic black hole is about three times the vibration response amplitude of the rudder body 1. Figure 27 and Figure 28 The results show that the additional acoustic black hole structure 9 transfers and absorbs more vibration energy from the rudder body 1. In order to maintain the constant amplitude vibration of the rudder body 1, the rudder containing the additional acoustic black hole needs to further increase the incoming flow Mach number to increase the work done by the aerodynamic force on the rudder body 1. This also explains why the flutter Mach number of the rudder containing the additional acoustic black hole structure is greater than the flutter Mach number of the rudder containing the equal-mass disk.

[0081] Compared to the mass block 13 and the equal-mass disk 14, the acoustic black hole structure has a better flutter suppression effect on the rudder body 1. Because mass factors can significantly affect the flutter of the rudder body 1, the masses of the mass block 13, the equal-mass disk structure 14, and the acoustic black hole structure are set to the same to avoid the influence of mass factors on the flutter results. Although the equal-mass disk 14 and the acoustic black hole structure have rich modes and can well match the frequency of the rudder body 1 structure, both have dynamic vibration absorption functions and can effectively transfer energy, the energy concentration effect of the acoustic black hole structure, that is, the energy transferred from the rudder body 1 to the acoustic black hole structure through dynamic vibration absorption can be better transferred to the edges of the acoustic black hole structure through the energy concentration effect of the acoustic black hole structure for damping and consumption. The final manifestation is that under the same incoming flow conditions, the damping of the acoustic black hole structure absorbs more energy than the damping of the equal-mass disk 14. To maintain the critical flutter state of the rudder body 1, it is necessary to increase the incoming flow velocity to increase the work done by the aerodynamic force on the rudder body 1.

[0082] In summary, the acoustic black hole structure can not only effectively suppress the flutter of the rudder body 1, but also has obvious advantages. The research results show that under the same mass conditions, the flutter amplitude of the rudder body 1 containing the acoustic black hole structure is lower than that of the rudder body 1 without the acoustic black hole structure, and the critical flutter speed is significantly improved. The specific advantages are mainly reflected in the following two aspects: First, the control method for achieving rudder flutter suppression is simple. Traditional active flutter suppression

[0083] While complex aerodynamic servo control laws are required to suppress the vibration of the rudder body 1, this embodiment 5 simply requires the installation of an additional acoustic black hole structure within the rudder body 1 to suppress the vibration of the rudder body 1, and the vibration control effect is significant. Second, it significantly reduces flight costs. Although configuring the rudder body with mass can effectively suppress rudder flutter, doing so will increase the aircraft's takeoff weight and increase fuel consumption costs. The acoustic black hole structure of this embodiment is small in size, and its mass accounts for less than 3% of the mass of the rudder body 1, and does not increase the flight cost of the aircraft.

[0084] 0 This specification uses specific examples to illustrate the principles and implementation methods of the present invention.

[0085] The above embodiments are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary according to the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A rudder with an attached acoustic black hole, characterized in that: The rudder comprises a rudder body and an acoustic black hole structure, wherein a cavity is provided inside the rudder body, a base is provided inside the rudder body, the acoustic black hole structure is located in the cavity and is arranged on the base, and the acoustic black hole structure and the base are detachably connected; The acoustic black hole structure includes one or two acoustic black hole components; The acoustic black hole assembly includes a damping plate and an acoustic black hole, one end of the damping plate is connected to one end of the acoustic black hole, and the acoustic black hole is provided with a connecting hole, and the connecting hole is eccentrically arranged; Both ends of the damping plate and the acoustic black hole are planes. One end of the damping plate is connected to the large end of the acoustic black hole. The outer contour of the small end of the acoustic black hole is smaller than the outer contour of the large end of the acoustic black hole. There is a curved surface structure between the small end of the acoustic black hole and the large end of the acoustic black hole, and the thickness of the curved surface structure varies in the form of a power exponent.

2. The rudder with an attached acoustic black hole according to claim 1, characterized in that: The outer contour size of the large end of the acoustic black hole is the same as the outer contour size of the damping plate.

3. The rudder with an attached acoustic black hole according to claim 1, characterized in that: The damping plate is annular, and the first through hole of the damping plate is communicated with the connecting hole.

4. The rudder with an attached acoustic black hole according to claim 1, characterized in that: When the acoustic black hole structure includes two acoustic black hole components, the small end of the acoustic black hole of one acoustic black hole structure passes through the damping plate of the other acoustic black hole structure and is connected to the large end of the acoustic black hole of the other acoustic black hole structure, and the connecting holes of the two acoustic black holes are concentrically arranged.

5. The rudder with an attached acoustic black hole according to claim 4, characterized in that: An annular gasket is arranged between the small end of the acoustic black hole of one acoustic black hole structure and the large end of the acoustic black hole of another acoustic black hole structure, and the annular gasket is provided with a second through hole, which is concentrically arranged with the connecting hole of each acoustic black hole.

6. The rudder with an attached acoustic black hole according to claim 1, characterized in that: The projection of the acoustic black hole on the plane perpendicular to the axis of the connecting hole is fan-shaped, and the projection of the damping plate on the plane perpendicular to the axis of the connecting hole is arc-shaped. The damping plate includes an inner arc edge and an outer arc edge. The inner arc edge is located on the inner side of the outer arc edge. The outer arc edge has the same size as the arc edge of the acoustic black hole, and the outer arc edge coincides with the projection of the arc edge on the plane perpendicular to the axis of the connecting hole.

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