Metamaterial silencer

Abstract

The application provides a metamaterial muffler, comprising: a main body section, the main body section comprising a low-frequency muffling module and a medium-frequency muffling module connected, a plurality of low-frequency muffling channels provided in the low-frequency muffling module and a plurality of medium-frequency muffling channels provided in the medium-frequency muffling module are in one-to-one correspondence and in communication; a transition section, at least one end of the main body section is connected with the transition section, the transition section comprises a plurality of air guide modules, the plurality of air guide modules are spliced with each other and are arranged in one-to-one correspondence with the plurality of low-frequency muffling channels; each air guide module comprises: an outer frame, which is hollow; an inner frame, which is arranged in the outer frame, the inner frame is hollow to form an air guide channel, a first end of the inner frame is fixedly connected with a first end of the outer frame in a circumferential direction, a second end of the inner frame is flush with a second end of the outer frame, an inner diameter of the inner frame gradually decreases in a direction towards the second end of the inner frame, an elastic membrane is fixed to an inner wall of the inner frame, and the second end of the inner frame is arranged towards the main body section; a baffle, which blocks a space between the inner frame and the outer frame at the second end of the inner frame, and the inner frame, the outer frame and the baffle enclose a cavity.

Description

Technical Field

[0001] The present invention relates to the technical field of mufflers, and in particular to a metamaterial muffler. Background Art

[0002] Silencers are widely used in ventilation ducts. Traditional mufflers use porous sound-absorbing materials or perforated plates mounted on the sidewalls to attenuate noise within the duct. However, these mufflers are ineffective at attenuating low-frequency sound waves, resulting in good mid- and high-frequency sound insulation and poor low-frequency sound insulation. To overcome this limitation, researchers have developed an acoustic metamaterial broadband sound isolator based on a thin-film resonator. Its frequency range and amount of sound insulation can be adjusted by adjusting the design of the thin-film resonator and the volume of the sealed cavity, allowing for separate low-, mid-, or high-frequency sound insulation. Typically, when broadband noise reduction is required, a metamaterial muffler is constructed by stacking multiple layers. Different layers consist of low-, mid-, and high-frequency modules to address low-, mid-, and high-frequency noise, respectively. A transition section is connected to the air inlet side to introduce airflow. In practical scenarios, the channel length of a traditional muffler must be relatively long. However, with a metamaterial muffler, the channel length can be reduced to one-fourth to one-fifth to achieve the same sound insulation, leveraging its compact size. However, in some special scenarios where the installation space is severely limited, the size of the metamaterial silencer that integrates low-frequency, medium-frequency and high-frequency modules cannot meet the installation requirements while eliminating noise in a wide frequency range, and still needs to be further reduced in size. Summary of the Invention

[0003] In view of this, the present invention provides a metamaterial muffler to solve the above technical problems.

[0004] The metamaterial muffler provided by the present invention comprises:

[0005] The main body section includes a low-frequency muffler module and a medium-frequency muffler module connected to each other, wherein the low-frequency muffler module is provided with a plurality of low-frequency muffler channels, and the medium-frequency muffler module is provided with a plurality of medium-frequency muffler channels, and the plurality of low-frequency muffler channels and the plurality of medium-frequency muffler channels are connected in a one-to-one correspondence;

[0006] A transition section, wherein at least one end of the main section is connected to the transition section, and the transition section includes a plurality of air guide modules, the plurality of air guide modules are spliced ​​together and arranged in a one-to-one correspondence with the plurality of low-frequency muffler channels;

[0007] Each of the air guide modules comprises:

[0008] An outer frame, wherein the outer frame is hollow;

[0009] an inner frame, the inner frame being disposed within the outer frame, the inner frame being hollow to form an air guide channel, the first end of the inner frame being circumferentially fixedly connected to the first end of the outer frame, the second end of the inner frame being flush with the second end of the outer frame, and the inner diameter of the inner frame gradually decreasing in a direction toward the second end thereof, an elastic membrane being fixed on an inner wall of the inner frame, and the second end of the inner frame being disposed toward the main body segment;

[0010] A shielding plate is provided at the second end of the inner frame to block the space between the inner frame and the outer frame, so that the inner frame, the outer frame and the shielding plate enclose a cavity.

[0011] Optionally, the inner frame is formed by connecting multiple side panels end to end in sequence, the first end of each side panel is connected to the first end of the outer frame, the second end of each side panel is connected to the shielding plate, and the elastic membrane is fixed on each side panel.

[0012] Optionally, each of the side panels is configured as an isosceles trapezoid, the upper base of each side panel is connected to the shielding plate, the lower base of each side panel is connected to the first end of the outer frame, and the waists of adjacent side panels are connected.

[0013] Optionally, the angle between the side panel and the outer frame ranges from 10° to 25°.

[0014] Optionally, the width of the elastic membrane accounts for 15%-30% of the width of the lower bottom of the side panel.

[0015] Optionally, the air guide module further includes: a partition plate, which is arranged in the cavity, connects the inner frame and the outer frame, and divides the cavity into a plurality of independent chambers.

[0016] Optionally, the outer frame is formed by connecting a plurality of frame plates end to end in sequence.

[0017] Optionally, the metamaterial muffler further includes a reinforcement plate, which is fixedly connected to the circumference of the transition section.

[0018] Optionally, a mounting flange is fixed to one end of the transition section away from the main body section.

[0019] Optionally, a connecting flange is fixed to at least one end of the main body section, and the transition section is connected to the main body section via the connecting flange.

[0020] Compared with the prior art, the above technical solution provided by the present invention has at least the following beneficial effects:

[0021] By adopting the metamaterial silencer of the present invention, the low-frequency silencer module in the main section eliminates low-frequency noise, the medium-frequency silencer module eliminates medium-frequency noise, and each wind guide module in the transition section uses a thin film resonator composed of a thin film and a cavity to eliminate high-frequency noise. Therefore, there is no need to set a high-frequency silencer module in the main section. With the help of the cooperation of the low-frequency silencer module, the medium-frequency silencer module and the transition section, the silencer effect in a wide frequency range can be achieved, the overall length and volume of the silencer are reduced, and the advantages of the short channel and small volume of the metamaterial silencer are ensured, so that it can be widely used when space is limited. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A three-dimensional structural diagram of a metamaterial muffler according to an embodiment of the present invention;

[0023] Figure 2 for Figure 1 A three-dimensional structural diagram of the transition section of the metamaterial muffler shown;

[0024] Figure 3 for Figure 2 a side view of the transition section shown;

[0025] Figure 4 for Figure 2 A three-dimensional structural diagram of the air guide module of the transition section shown;

[0026] Figure 5 for Figure 4 Side view of the air guide module shown.

[0027] Reference numerals:

[0028] 100: Main section; 200: Transition section; 1: Air guide module; 11: Outer frame; 111: Frame plate; 12: Inner frame; 121: Side plate; 13: Elastic membrane; 2: Reinforcement plate; 3: Mounting flange; 4: Connecting flange. DETAILED DESCRIPTION

[0029] The embodiments of the present invention will be further described below with reference to the accompanying drawings. In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only simplified descriptions for the convenience of describing the present invention, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0030] Figure 1A three-dimensional structural diagram of a metamaterial muffler according to an embodiment of the present invention; Figure 2 for Figure 1 A three-dimensional structural diagram of the transition section of the metamaterial muffler shown; Figure 3 for Figure 2 a side view of the transition section shown; Figure 4 for Figure 2 A three-dimensional structural diagram of the air guide module of the transition section shown; Figure 5 for Figure 4 Side view of the air guide module shown.

[0031] like Figure 1-Figure 5 As shown, the metamaterial silencer includes a main section 100 and a transition section 200. The main section 100 includes a low-frequency silencer module and a medium-frequency silencer module connected to each other. The low-frequency silencer module is provided with multiple low-frequency silencer channels, and the medium-frequency silencer module is provided with multiple medium-frequency silencer channels. The multiple low-frequency silencer channels and the multiple medium-frequency silencer channels are connected one by one; at least one end of the main section 100 is connected to the transition section 200, and the transition section 200 includes multiple air guide modules 1. The multiple air guide modules 1 are spliced ​​with each other and are arranged one by one with the multiple low-frequency silencer channels; each air guide module 1 includes an outer frame 11, an inner frame 12 and a shielding plate, and the outer frame 11 is hollow. ; The inner frame 12 is arranged in the outer frame 11, and the inner frame 12 is hollow to form an air guide channel. The first end of the inner frame 12 is circumferentially fixedly connected to the first end of the outer frame 11, and the second end of the inner frame 12 is flush with the second end of the outer frame 11, and the inner diameter of the inner frame 12 gradually decreases in the direction toward its second end. An elastic membrane 13 is fixed on the inner wall of the inner frame 12, and the second end of the inner frame 12 is arranged toward the main section 100; the baffle blocks the space between the inner frame 12 and the outer frame 11 at the second end of the inner frame 12, so that the inner frame 12, the outer frame 11 and the baffle enclose a cavity.

[0032] When the elastic membrane 13 is fixed to the inner wall of the inner frame 12, a certain pulling force is applied to the elastic membrane 13, so that it is in a certain degree of tension. Then, a thin film resonator composed of a membrane and an air layer is formed between the elastic membrane 13 and the cavity. The thin film resonator has a large sound absorption effect near the resonant frequency. When noise passes through the air guide channel, the resonance state generated by the coupling between the cavity and the elastic membrane 13 interacts with the noise, which can effectively reduce the noise. The frequency of the resonance state is closely related to the volume of the cavity. The larger the cavity volume, the lower the resonance state frequency, and the lower the noise frequency band to which the wind guide module 1 responds; the smaller the cavity volume, the higher the resonance state frequency, and the higher the noise frequency band to which the wind guide module 1 responds. The volume of the cavity of each wind guide module 1 in the transition section 200 is smaller than the volume of the corresponding cavity in the medium-frequency silencer module. Therefore, each wind guide module 1 in the transition section 200 can effectively silence high-frequency noise in the noise. Thus, the low-frequency silencer module eliminates low-frequency noise, the medium-frequency silencer module eliminates medium-frequency noise, and the wind guide module 1 in the transition section 200 eliminates high-frequency noise. The combination of the three realizes the noise elimination effect of the metamaterial silencer on noise within a wide frequency range of low, medium and high frequencies.

[0033] By using the metamaterial silencer of the present invention, the low-frequency silencer module in the main section 100 eliminates low-frequency noise, the medium-frequency silencer module eliminates medium-frequency noise, and each wind guide module 1 in the transition section 200 uses a thin film resonator composed of a thin film and a cavity to eliminate high-frequency noise. Therefore, there is no need to set a high-frequency silencer module in the main section 100. With the help of the cooperation of the low-frequency silencer module, the medium-frequency silencer module and the transition section 200, the noise reduction effect in a wide frequency range can be achieved, the overall length and volume of the silencer are reduced, and the advantages of the short channel and small volume of the metamaterial silencer are ensured, so that it can be widely used when space is limited.

[0034] In this embodiment, the low-frequency muffler module includes nine low-frequency muffler channels, and the medium-frequency muffler module includes nine medium-frequency muffler channels, which are arranged in three rows and three columns. The low-frequency muffler channels and the medium-frequency muffler channels are connected one by one. Correspondingly, the transition section 200 includes nine air guide modules 1 arranged in the same manner, such as Figure 1-Figure 5 As shown, the outer frame 11 of each air guide module 1 is a hollow cuboid, and the side walls of adjacent outer frames 11 are fixedly connected. The inner frame 12 of each air guide module 1 is arranged in the outer frame 11 and is the same length as the outer frame 11. The end of the inner frame 12 facing away from the main section 100 is circumferentially fixedly connected to the end of the outer frame 11 facing away from the main section 100. The end of the inner frame 12 facing the main section 100 is flush with the end of the outer frame 11 facing the main section 100. In the direction toward the main section 100, the inner diameter of the inner frame 12 gradually decreases, that is, the distance between the inner frame 12 and the outer frame 11 gradually increases. The baffle is connected to the inner frame 12 and the end of the outer frame 11 facing the main section 100, and the three enclose a cavity for noise reduction with the elastic membrane 13 on the inner frame 12.

[0035] The inner diameter of the inner frame 12 at the end facing the main section 100 is consistent with the dimensions of the low-frequency and mid-frequency muffler channels, and they are interconnected. The inner diameter of the end facing away from the main section 100 is larger than the dimensions of the low-frequency and mid-frequency muffler channels, resulting in the inner frame 12 having a bell-shaped configuration. When the transition section 200 is connected to the windward side of the main section 100, the bell-shaped configuration of the inner frame 12 can smoothly guide airflow into the low-frequency and mid-frequency muffler channels of the main section 100, reducing wind resistance. When the transition section 200 is connected to the leeward side of the main section 100, the bell-shaped configuration of the inner frame 12 can improve the smoothness of the outgoing airflow. In this embodiment, the windward side and the leeward side of the main section 100 are both connected to a transition section 200, and the two transition sections 200 are configured identically, so that the airflow can be smoothly introduced from the transition section 200 on the windward side into the main section 100, and the smoothness of the airflow discharged from the main section 100 can be improved. At the same time, when the airflow passes through the two transition sections 200, the high-frequency noise is silenced by the thin film resonator of the wind guide module 1. According to the specific settings of the low-frequency silencer channel of the low-frequency silencer module and the intermediate-frequency silencer channel of the intermediate-frequency silencer module, the number and position of the wind guide modules 1 in the transition section 200 are adjusted accordingly. The transition section 200 can be set only on one side of the main section 100, and the volume of the cavity can be appropriately adjusted according to the frequency of the noise to be eliminated. The low-frequency silencer module and the intermediate-frequency silencer module of the metamaterial structure are mature existing technologies, and their specific structure and working principle will not be repeated here.

[0036] Optionally, the inner frame 12 is formed by connecting a plurality of side panels 121 end to end, with the first end of each side panel 121 connected to the first end of the outer frame 11, the second end of each side panel 121 connected to the shielding plate, and an elastic membrane 13 fixed to each side panel 121. This arrangement simplifies the structure of the inner frame 12 and facilitates its acquisition and assembly.

[0037] like Figure 2 and Figure 4 As shown, in this embodiment, the inner frame 12 is composed of four side panels 121 connected end to end. One end of each side panel 121 is connected to the edge of the outer frame 11 facing away from the main section 100, while the other end extends toward the main section 100 until it is flush with the outer frame 11 and connected to the shielding plate. Because the inner diameter of the inner frame 12 gradually decreases toward the main section 100, each side panel 121 is tilted, maintaining a certain distance from the outer frame 11. The flat, inclined surface can smoothly direct airflow into the main section 100 when positioned on the windward side of the main section 100, and can guide airflow smoothly out when positioned on the leeward side of the main section 100. As shown in the figure, an elastic membrane 13 is fixed to the same position on each of the four side panels 121. The shape, size, and number of the side panels 121 that comprise the inner frame 12 can be adjusted according to actual application.

[0038] Optionally, each side panel 121 is configured as an isosceles trapezoid, with the upper base of each side panel 121 connected to the shielding plate, the lower base of each side panel 121 connected to the first end of the outer frame 11, and the waists of adjacent side panels 121 connected. This configuration allows the side panels 121 to be uniformly manufactured and easily assembled.

[0039] like Figure 4 and Figure 5 As shown, in this embodiment, each side panel 121 is the same isosceles trapezoid and has the same inclination angle relative to the outer frame 11. The lower base with a larger length is connected to the end of the outer frame 11 away from the main section 100, and the upper base with a smaller length faces the main section 100 and is connected to the baffle, so that the cross-section of the inner frame 12 away from the end of the main section 100 is a larger square, and the cross-section toward the end of the main section 100 is a smaller square.

[0040] Optionally, the angle between the side panels 121 and the outer frame 11 ranges from 10° to 25°. The inner cavity formed by connecting the side panels 121 end to end, the outer frame 11, and the shielding plate enclose a cavity. The size of the cavity is directly related to the frequency of the noise eliminated. The transition section 200 mainly eliminates the high-frequency portion of the noise. The elastic membrane 13 is required to cooperate with the smaller cavity to form a thin film resonator that is effective for high-frequency noise. Setting the angle between the side panels 121 and the outer frame 11 to the above range ensures that the volume of the cavity is within a certain range, preventing the cavity from being too large and affecting the silencing effect on high-frequency noise.

[0041] like Figure 4 As shown, in this embodiment, the angle between the side panel 121 and the outer frame 11 is approximately 20°. Depending on the actual application, the angle between the two can also be set to any angle within the above range, such as 10°, 15°, 25°, etc.

[0042] Optionally, the width of the elastic membrane 13 accounts for 15%-30% of the width of the lower base of the side panel 121. The width of the elastic membrane 13 affects its frequency response and acoustic properties. A wider elastic membrane 13 generally has a lower resonant frequency, while a narrower elastic membrane 13 has a higher resonant frequency. The transition section 200 primarily eliminates the high-frequency portion of noise. Therefore, the width of the elastic membrane 13 should not be too large. Setting it within the above width range can ensure the thin film resonator's ability to eliminate high-frequency noise.

[0043] like Figure 5 As shown, in this embodiment, the width of the elastic membrane 13 is approximately 30% of the lower base width of the trapezoidal side panel 121. Depending on the actual application, the width of the elastic membrane 13 can be appropriately adjusted within the above range. For example, the width of the elastic membrane 13 is 15%, 20%, 25%, etc. of the lower base width of the trapezoidal side panel 121.

[0044] Optionally, the air guide module 1 further includes a partition plate (not shown), which is disposed within the cavity, connecting the inner frame 12 and the outer frame 11, and dividing the cavity into a plurality of independent chambers. The partition plate is used to separate the cavity enclosed by the outer frame 11, the inner frame 12, and the baffle into a plurality of chambers, so that the elastic membrane 13 fixed on the inner frame 12 no longer corresponds to a larger cavity, but corresponds to a smaller cavity. Thus, the elastic membrane 13 and its corresponding cavity form a new thin film resonator, and because the volume of the cavity is smaller than the volume of the entire cavity, the new thin film resonator formed by the elastic membrane 13 and the corresponding cavity can respond to noise in a higher frequency range, that is, the transition section 200 can eliminate higher frequency high-frequency noise.

[0045] like Figure 4 As shown, in this embodiment, the inner frame 12 is composed of four side panels 121 connected end to end, with a total of four partitions. One end of each partition is connected to the intersection line between two adjacent side panels 121, and the other end is connected to the outer frame 11, dividing the cavity into four independent chambers. An elastic membrane 13 is fixed to each side panel 121. Thus, each elastic membrane 13 and the corresponding chamber behind it form a thin film resonator to muffle high-frequency noise in the airflow flowing through the air guide channel. The number of partitions can be adjusted according to actual application. For example, two partitions can be provided to divide the cavity into two independent chambers, or three partitions can be provided to divide the cavity into three independent chambers. The volume of each chamber can be equal or unequal.

[0046] Optionally, the outer frame 11 is formed by connecting a plurality of frame plates 111 end to end. This arrangement simplifies the structure of the outer frame 11, and the frame plates 111 are uniformly manufactured for ease of assembly.

[0047] like Figure 4 As shown, in this embodiment, the outer frame 11 is a hollow cuboid, formed by splicing four rectangular frame panels 111 end to end, and one end of the inner frame 12 is connected to the end of the frame panel 111 away from the main body section 100. The shape, size, and number of the frame panels 111 can be adjusted according to the required size of the outer frame 11.

[0048] Optionally, the metamaterial muffler further includes a reinforcement plate 2, which is fixedly connected to the circumference of the transition section 200. The transition section 200 is composed of multiple air guide modules 1. The reinforcement plate 2 is provided and connected to the circumference of the transition section 200 to further strengthen the connection between the air guide modules 1.

[0049] like Figure 1 As shown, the transition section 200 includes three rows and three columns of nine air guide modules 1 , and reinforcement plates 2 are fixed to the upper, lower, left and right sides of the outer periphery of the transition section 200 .

[0050] Optionally, a mounting flange 3 is fixed to one end of the transition section 200 away from the main section 100. The mounting flange 3 is pre-connected to the transition section 200, and when the metamaterial muffler is fixed, it can be fixed to the desired position with the help of the mounting flange 3, saving installation time.

[0051] like Figure 1 As shown, the two ends of the main section 100 are respectively connected to the transition sections 200, and the ends of the two transition sections 200 away from the main section 100 are fixed with mounting flanges 3. The mounting flanges 3 are pre-opened with mounting holes, which are convenient for fixing the metamaterial silencer by using bolts to pass through the mounting holes for installation.

[0052] Optionally, a connecting flange 4 is fixed to at least one end of the main section 100, and the transition section 200 is connected to the main section 100 via the connecting flange 4. The flange connection between the main section 100 and the transition section 200 facilitates disassembly and has a sufficiently high connection strength.

[0053] like Figure 1 As shown, connecting flanges 4 are fixed to opposite ends of the main body section 100 , and the two transition sections 200 are fixed to the two ends of the main body section 100 through the connecting flanges 4 .

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A metamaterial muffler, characterized in that: include: The main body section includes a low-frequency muffler module and a medium-frequency muffler module connected to each other, wherein the low-frequency muffler module is provided with a plurality of low-frequency muffler channels, and the medium-frequency muffler module is provided with a plurality of medium-frequency muffler channels, and the plurality of low-frequency muffler channels and the plurality of medium-frequency muffler channels are connected in a one-to-one correspondence; A transition section, wherein at least one end of the main section is connected to the transition section, and the transition section includes a plurality of air guide modules, the plurality of air guide modules are spliced ​​together and arranged in a one-to-one correspondence with the plurality of low-frequency muffler channels; Each of the air guide modules comprises: An outer frame, wherein the outer frame is hollow; an inner frame, the inner frame being disposed within the outer frame, the inner frame being hollow to form an air guide channel, the first end of the inner frame being circumferentially fixedly connected to the first end of the outer frame, the second end of the inner frame being flush with the second end of the outer frame, and the inner diameter of the inner frame gradually decreasing in a direction toward the second end thereof, an elastic membrane being fixed on an inner wall of the inner frame, and the second end of the inner frame being disposed toward the main body segment; A shielding plate is provided at the second end of the inner frame to block the space between the inner frame and the outer frame, so that the inner frame, the outer frame and the shielding plate enclose a cavity.

2. The metamaterial muffler according to claim 1, characterized in that: The inner frame is formed by connecting multiple side panels end to end in sequence, the first end of each side panel is connected to the first end of the outer frame, the second end of each side panel is connected to the shielding plate, and the elastic membrane is fixed to each side panel.

3. The metamaterial muffler according to claim 2, characterized in that: Each of the side panels is configured as an isosceles trapezoid, the upper base of each side panel is connected to the shielding plate, the lower base of each side panel is connected to the first end of the outer frame, and the waists of adjacent side panels are connected.

4. The metamaterial muffler according to claim 3, characterized in that: The included angle between the side panel and the outer frame is in the range of 10°-25°.

5. The metamaterial muffler according to claim 3, characterized in that: The width of the elastic membrane accounts for 15%-30% of the width of the lower bottom of the side plate.

6. The metamaterial muffler according to any one of claims 1 to 5, characterized in that: The air guide module further includes: A partition plate is disposed in the cavity, connecting the inner frame and the outer frame, and dividing the cavity into a plurality of independent chambers.

7. The metamaterial muffler according to any one of claims 1 to 5, characterized in that: The outer frame is formed by connecting a plurality of frame plates end to end in sequence.

8. The metamaterial muffler according to any one of claims 1 to 5, characterized in that: Also includes: A reinforcing plate is fixedly connected to the circumference of the transition section.

9. The metamaterial muffler according to any one of claims 1 to 5, characterized in that: A mounting flange is fixed to one end of the transition section away from the main body section.

10. The metamaterial muffler according to any one of claims 1 to 5, characterized in that: A connecting flange is fixed to at least one end of the main body section, and the transition section is connected to the main body section via the connecting flange.

Images