A rail transit sound barrier based on phononic crystal unit cells

Abstract

The present invention discloses a rail transit sound barrier based on phononic crystal cells, which is divided into several cells of equal volume by dividing modules; a resonance cavity with an opening on one side is embedded in each cell; one side of the opening of the resonance cavity faces the sound source; the opening extends outward in a trumpet shape to increase the sound receiving area; several phononic crystal cells that do not contact each other are fixedly arranged in the resonance cavity; the resonance cavity in the present invention can achieve triple acoustic performance improvements, namely sound insulation, sound elimination and sound absorption: its overall appearance belongs to a Holmhelix resonance cavity, which is itself a good sound elimination device, which is the first sound elimination; the trumpet-like opening structure on the sound source side is conducive to the introduction of sound waves, and the phononic crystal cells are arranged inside, which is the second sound insulation of the device; the tail adopts a boss with the same size as the end of the trumpet mouth, which is conducive to the flow of sound waves, and a certain thickness of sound-absorbing rock wool is used on the inner wall of the tail, which is the third sound absorption.

Description

Technical Field

[0001] The present invention relates to the field of sound barriers, and in particular to a rail transit sound barrier based on phononic crystal unit cells. Background Art

[0002] In the field of rail transit noise control, the main method is to install sound barriers on both sides of the line, so it is necessary to further improve the acoustic performance and service performance of the sound barriers.

[0003] When running, rail trains not only cause serious noise pollution, but also form multiple noise sources, and the sound radiation can cover the entire frequency band. Therefore, traditional sound barriers can no longer meet the needs of rail transit noise prevention and control in terms of sound insulation performance. There are also problems with the singleness of noise prevention and control and the difficulty of replacement. In particular, the installation requirements of some rail transit lines are extremely strict. While improving the acoustic performance of the sound barrier, it is required to retain its appearance as much as possible. Therefore, when multiple needs coexist, it is difficult to meet the above requirements at the same time. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a rail transit sound barrier based on phononic crystal cells, which is easy to replace, has strong applicability, and can simultaneously meet the requirements of sound insulation, sound elimination and sound absorption.

[0005] To this end, the present invention adopts the following technical solutions:

[0006] A rail transit sound barrier based on phononic crystal unit cells, wherein a plurality of sound barrier unit panels are installed between two I-shaped steel columns. The sound barrier unit panels divide the area between the two I-shaped steel columns into a plurality of sound barrier blocks, and the sound barrier blocks are divided into a plurality of cells of equal volume by a dividing module.

[0007] Each of the units is embedded with a resonance cavity with an opening on one side;

[0008] One side of the opening of the resonance cavity faces the sound source; the opening extends outward in a trumpet shape to increase the sound receiving area;

[0009] A plurality of phononic crystal unit cells that are not in contact with each other are fixedly arranged in each of the resonance cavities;

[0010] The outer layer of the phononic crystal unit cell is a hexagonal tube, and the inner layer is a hexagonal plum blossom tube, and the two are not in contact; the hexagonal tube has a first notch on the side facing the sound source.

[0011] Preferably, a front panel and a back panel are provided on both sides of the sound barrier block.

[0012] Preferably, the dividing module is specifically a number of vertical ribs and transverse ribs arranged at equal intervals, and the vertical ribs and transverse ribs are also used to increase the stability of the unit plates on the upper and lower sides of the sound barrier block.

[0013] Preferably, a boss is further provided on a side of the resonance cavity away from the sound source, the area of ​​the boss is the same as the area of ​​the opening, and the height of the boss and the opening of the same resonance cavity is the same.

[0014] Preferably, the long side of the opening on the resonance cavity is parallel to the horizontal plane, and the area of ​​the opening occupies 32% of the plane.

[0015] Preferably, the inner surface of the resonance cavity away from the sound source is paved with sound-absorbing rock wool with a thickness of 5mm-8mm.

[0016] Preferably, the gap between the resonance cavity and the cells is filled with sound-absorbing rock wool.

[0017] Preferably, the first notch is one side of the hexagon of the hexagonal tube.

[0018] Preferably, four phononic crystal unit cells are arranged in each resonance cavity.

[0019] Preferably, the trumpet-shaped opening extending outward in a trumpet shape is divided into upper and lower sides and left and right sides, the four sides are seamlessly connected, the width of the four sides is set between 25mm and 35mm, the angle between the upper and lower sides of the trumpet-shaped opening and the side surfaces on which they are located is between 45° and 60°, and the angle between the left and right sides of the trumpet-shaped opening and the side surfaces on which they are located is between 30° and 45°.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention redesigns the internal structure of the traditional sound barrier and retains the overall shape of the original sound barrier as much as possible, so it will not affect the overall design of the original rail transit line.

[0022] 2. The sound barrier of the present invention increases the stability of the sound barrier unit plate through the cells and reduces its own vibration noise; the designed horizontal and vertical ribs are conducive to the replacement and maintenance of the resonance cavity.

[0023] 3. The sound barrier of the present invention adopts a cell design, which greatly simplifies the subsequent maintenance method of the sound barrier. If the resonance cavity inside a cell is damaged, the resonance cavity of the same type can be directly replaced, which solves the current problem that the sound barrier is difficult to repair after being damaged, and greatly reduces the subsequent maintenance cost.

[0024] 4. The resonance cavity of the present invention achieves triple acoustic performance improvements: sound insulation, sound attenuation, and sound absorption. First, its overall shape is a Holmheitz resonance cavity, which is itself an excellent sound attenuation device. This design represents the first level of sound attenuation. The horn-shaped opening on the sound source side facilitates the transmission of sound waves, and the phononic crystal unit cell is arranged inside. This design represents the second level of sound insulation. The tail portion uses a boss of the same size as the end of the horn mouth to facilitate the flow of sound waves. The inner wall of the tail portion uses a certain thickness of sound-absorbing rock wool, which represents the third level of sound absorption. Therefore, the resonance cavity of the present invention has superior acoustic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0026] Figure 2 This is a schematic front view of the structure of a traditional sound barrier according to the present invention;

[0027] Figure 3 It is a schematic diagram of the back side of the traditional sound barrier structure of the present invention;

[0028] Figure 4 Schematic diagram of the position structure of the cell in the present invention;

[0029] Figure 5 is a three-dimensional schematic diagram of the resonant cavity in the present invention;

[0030] Figure 6 is a schematic cross-sectional perspective view of the resonant cavity of the present invention;

[0031] Figure 7 is a schematic diagram of a longitudinal cross-section of the resonant cavity of the present invention;

[0032] Figure 8 Schematic diagram of the top view of the phononic crystal unit cell in one embodiment of the present invention;

[0033] Figure 9 A resonant cavity comprising a quincunx-shaped phononic crystal unit cell;

[0034] Figure 10 It is a resonant cavity containing a tetragonal quincunx-shaped phononic crystal unit cell;

[0035] Figure 11 A resonant cavity comprising a cross-sandwich plate-shaped phononic crystal unit cell;

[0036] Figure 12 The resonant cavity comprises a cylindrical embedded quincunx-shaped phononic crystal unit cell;

[0037] Figure 13 A comparison chart of the noise reduction effects of crystal unit cells with various structures;

[0038] Figure 14 A comparison chart of the average acoustic transmission loss of crystal cells with various structures;

[0039] Figure 15 Schematic diagram of the structure in the cell of Comparative Example 2;

[0040] Figure 16 This is a comparison diagram of the noise reduction effect of the structure in comparative example 2;

[0041] Figure 17 This is a comparison chart of the noise reduction effects of the two resonant cavities in comparative example three.

[0042] In the picture:

[0043] 1. Front panel, 2. I-shaped steel column, 3. Back panel, 4. Sound barrier unit panel, 5. Cell, 6. Sound-absorbing rock wool, 7. Fixed grid. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0045] See also Figure 1-Figure 5 The rail transit sound barrier based on the phononic crystal unit cell of the present invention is installed on both sides of the rail transit line through the I-shaped steel columns 2. Several sound barrier unit panels 4 are horizontally erected between the two I-shaped steel columns 2. The sound barrier unit panels 4 divide the area between the two I-shaped steel columns 2 into several sound barrier blocks. A front panel 1 and a back panel 3 are also provided on both sides of each sound barrier block. The front panel 1 faces the side of the sound source and has pores.

[0046] In each sound barrier block, a dividing module is provided. The dividing module is a number of vertical ribs and horizontal ribs arranged at equal intervals. The dividing module is used to divide the sound barrier block into a number of cells 5 of equal volume.

[0047] In one embodiment of the present invention, the opening surface of each cell is a square with a side length of 250 mm; the thickness of the cell is 300 mm;

[0048] like Figure 6 and Figure 7 As shown, a resonant cavity is embedded in each cell 5. The volume of the resonant cavity is adapted to the volume of the cell 5. Any gap between the outer side of the resonant cavity and the cell 5 is filled with sound-absorbing rock wool. The resonant cavity is a cavity with an opening on one side close to the sound source. Four phononic crystal cells are evenly and fixedly arranged inside it. A fixed grid 7 is provided at the bottom of the resonant cavity to fix the phononic crystal cells.

[0049] like Figure 5As shown, the opening is located in the center of the opening surface of the resonant cavity, and the opening extends outward from the cavity in a trumpet shape. The area of ​​the hole accounts for the area of ​​the side where it is located. 32％； The side of the resonant cavity away from the sound source protrudes in the direction away from the cavity to form a boss, the area of ​​the boss is the same as the area of ​​the hole, and the horizontal position is also the same; the inner surface of the cavity on the side of the resonant cavity away from the sound source is also paved 5mm-8mm Thickness of sound-absorbing rock wool 6.

[0050] In the above embodiment, the opening surface of the resonant cavity is square, with a side length of 250 mm. The thickness of the resonant cavity is 260 mm. The trumpet-shaped opening is divided into upper and lower sides and left and right sides, which are seamlessly connected. The width of the four sides is set between 25 mm and 35 mm. The angle between the upper and lower sides of the trumpet-shaped opening and the opening surface is between 45° and 60°, and the angle between the left and right sides of the trumpet-shaped opening and the opening surface is between 30° and 45°. The long side of the hole in the opening surface is 200 mm, and the wide side is 100 mm. The long side of the hole is parallel to the horizontal plane. The thickness of the boss is 20 mm.

[0051] The outer layer of the phononic crystal unit cell is a hexagonal tube, and the inner layer is a hexagonal plum blossom tube; the side of the hexagonal tube close to the sound source is a notch; in the above embodiment, Figure 8 As shown, considering the thickness of the solid iron plate, the inner side length of the hexagonal tube is 53mm, and the outer side length is 58mm; the outer wall radius of the plum blossom-shaped tube is 13mm, and the inner wall radius is 11mm.

[0052] like Figure 6 and Figure 7 As shown, the resonant cavity utilizes the Holmheitz resonant cavity and phononic crystal theory, and the specific design is as follows:

[0053] 1. The phononic crystal unit cell adopts a hexagonal shape (the hexagonal edge is eliminated on the sound source side) and an internal hexagonal plum blossom design;

[0054] Second, a horn-shaped opening design is used on the sound source side to facilitate the transmission of sound waves into the resonance cavity;

[0055] 3. Since the more periods of the phononic crystal cell, the better the sound absorption effect, in view of the actual installation problem of the overall sound barrier, multi-period phononic crystals are not conducive to actual engineering applications. Therefore, the resonance cavity adopts a rectangular design and a layer of sound-absorbing rock wool is added to the inner wall of the tail, thereby achieving a third sound absorption effect.

[0056] In general, the present invention can achieve six levels of noise reduction, namely, the front panel reflected noise on the sound source side, the outer shell of the resonance cavity silencer, the phononic crystal unit cell silencer, the sound absorption and sound insulation on the back of the Holmhausen resonance cavity, and the back panel sound insulation; this structure effectively improves the acoustic performance of the sound barrier; the use of different phononic crystals effectively improves the sound insulation range, which can achieve effective control of various noises, and maintain the original shape of the sound barrier as much as possible, which is beneficial to its actual engineering application; the vertical ribs and horizontal ribs can effectively reduce the vibration noise of the sound barrier itself and improve its noise reduction function; and enhance the stability and service life of the sound barrier; the resonance cavity has the advantage of small size and can be prefabricated in batches, so it is also more conducive to later replacement and maintenance.

[0057] Comparative Example 1

[0058] The sound barrier unit panels in this comparative example are mounted on standard 150x150mm I-shaped steel columns. The panels feature protruding sides, facilitating effective integration with the I-shaped steel columns and enabling installation. The partitioning modules utilize a grid-like design to form multiple cells, each embedded within a resonant cavity. The sound barriers in this comparative example have four different structures, differing in the structure of the phononic crystal unit cells within the resonant cavity. The other components are identical.

[0059] The top view of the four phononic crystal unit cell structures in this comparative example is as follows Figures 9 to 12 As shown, Figure 9 A resonant cavity comprising a quincunx-shaped phononic crystal unit cell; Figure 10 It is a resonant cavity containing a tetragonal quincunx-shaped phononic crystal unit cell; Figure 11 A resonant cavity comprising a cross-sandwich plate-shaped phononic crystal unit cell; Figure 12 The resonant cavity comprises a cylindrical embedded quincunx-shaped phononic crystal unit cell;

[0060] Specifically, the acoustic transmission loss index is used to compare the actual use effects of these four structures with the structure of the present invention. Figure 13 As shown, by comparing the sound transmission loss and frequency images of the sound barriers using the above four structures and the sound barrier of the present invention, it can be clearly found that the sound transmission loss of the structure of the present invention is the highest, which reflects the excellent effect in sound insulation, sound elimination and sound absorption; Figure 13 The average of the sound transmission loss results of various structures at all frequencies is obtained Figure 14 The results show that, specifically, the structure of the present invention improves by 18.6dB, 20.4dB, 20.8dB and 8.1dB respectively compared with the cross-shaped plum blossom, square-shaped plum blossom and cross-shaped partition.

[0061] Comparative Example 2

[0062] The sound barrier unit plate in this comparative example is on a standard I-shaped steel column with a size of 150*150. Its two sides adopt a protruding design to facilitate the effective combination of the unit plate and the I-shaped steel column to achieve its installation. The division module adopts a grid design to form multiple units. In each unit cell, only four phononic crystal units are set. The outer layer is a notched hexagonal tube and the inner layer is a hexagonal plum blossom tube. That is, the structure of the phononic crystal unit cell of the present invention is the same as that of the phononic crystal unit cell. No resonance cavity is set outside the phononic crystal unit cell. Figure 15 shown.

[0063] This structure is compared with the structure of the present invention, and the following results are obtained when other conditions and structures are the same: Figure 16 As shown in the figure, the lighter colored histogram represents the structure of the present invention, and the darker colored histogram represents the structure in the comparative example. At various frequencies, the structure of the present invention has obvious advantages over the structure in the comparative example.

[0064] Comparative Example 3

[0065] Based on the present invention, the resonant cavity's opening area is enlarged to account for 48% of the opening surface. Specifically, the enlarged opening is 200 mm long and 150 mm wide. The trumpet-shaped opening is divided into upper and lower sides and left and right sides, which are seamlessly connected. The width of each side is set between 25 mm and 35 mm. The upper and lower sides of the trumpet-shaped opening form an angle between 45° and 60° with the opening surface, and the left and right sides form an angle between 30° and 45° with the opening surface. This is referred to as the second resonant cavity, and the structure of the present invention is referred to as the first resonant cavity.

[0066] like Figure 17 As shown, when other conditions are the same, the sound insulation caused by the structure of the present invention is compared with that of this comparative example. At different frequencies, except that the noise reduction level of the first resonance cavity is not as good as that of the second resonance cavity at low frequencies, the noise reduction effect of the first resonance cavity is obviously better at other frequencies.

Claims

1. A rail transit sound barrier based on phononic crystal unit cells, wherein a plurality of sound barrier unit panels are installed between two I-shaped steel columns. The sound barrier unit panels divide the area between the two I-shaped steel columns into a plurality of sound barrier blocks, characterized by: The sound barrier block is divided into a number of cells of equal volume by a division module; Each of the units is embedded with a resonance cavity with an opening on one side; One side of the opening of the resonance cavity faces the sound source; The opening extends outward in a trumpet shape to increase the sound receiving area; A plurality of phononic crystal unit cells that are not in contact with each other are fixedly arranged in each of the resonance cavities; The outer layer of the phononic crystal unit cell is a hexagonal tube, and the inner layer is a hexagonal plum blossom tube, and the two are not in contact; the hexagonal tube has a first notch on the side facing the sound source.

2. The rail transit sound barrier based on phononic crystal unit cells according to claim 1 is characterized by: A front panel and a back panel are also provided on both sides of the sound barrier block.

3. The rail transit sound barrier based on phononic crystal unit cells according to claim 1 is characterized by: The dividing module is specifically a number of vertical ribs and transverse ribs arranged at equal intervals. The vertical ribs and transverse ribs are also used to increase the stability of the unit plates on the upper and lower sides of the sound barrier block.

4. The rail transit sound barrier based on phononic crystal unit cells according to claim 1 is characterized by: A boss is further provided on the side of the resonance cavity away from the sound source. The area of ​​the boss is the same as the area of ​​the opening. The boss and the opening of the same resonance cavity are at the same height.

5. The rail transit sound barrier based on phononic crystal unit cells according to claim 1 is characterized by: The long side of the opening on the resonance cavity is parallel to the horizontal plane, and the area of ​​the opening occupies 32% of the plane.

6. The rail transit sound barrier based on phononic crystal unit cells according to claim 1 is characterized by: The inner surface of the resonance cavity away from the sound source is paved with sound-absorbing rock wool with a thickness of 5mm-8mm.

7. The rail transit sound barrier based on phononic crystal unit cells according to claim 5 is characterized by: The gap between the resonance cavity and the cells is filled with sound-absorbing rock wool.

8. The rail transit sound barrier based on phononic crystal unit cells according to claim 1 is characterized by: The first notch is one side of the hexagon of the hexagonal tube.

9. The rail transit sound barrier based on phononic crystal unit cells according to claim 1, characterized in that: Four phononic crystal cells are set in each resonance cavity.

10. The rail transit sound barrier based on phononic crystal unit cells according to claim 1, characterized in that: The trumpet-shaped opening extending outward in a trumpet shape is divided into upper and lower sides and left and right sides, and the four sides are seamlessly connected. The width of the four sides is set between 25mm and 35mm. The angle between the upper and lower sides of the trumpet-shaped opening and the side surfaces on which they are located is between 45° and 60°, and the angle between the left and right sides of the trumpet-shaped opening and the side surfaces on which they are located is between 30° and 45°.

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