CN217606549U - Frequency-adjustable Helmholtz resonator - Google Patents
Frequency-adjustable Helmholtz resonator Download PDFInfo
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- CN217606549U CN217606549U CN202220509920.6U CN202220509920U CN217606549U CN 217606549 U CN217606549 U CN 217606549U CN 202220509920 U CN202220509920 U CN 202220509920U CN 217606549 U CN217606549 U CN 217606549U
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Abstract
The utility model discloses a frequency-adjustable Helmholtz resonator, which comprises a shell, wherein a cylindrical cavity is horizontally arranged in the shell, a rotatable cylinder is arranged at the center of the cylindrical cavity, one end of the cylinder extends out of the shell, and a knob is fixed at the end part of the cylinder; the top end of the partition board positioned on the upper layer is in close contact with the inner wall of the cylindrical cavity, the bottom end of the partition board positioned on the lower layer is in close contact with the outer wall of the cylinder, the front end and the rear end of the partition board are fixed on the shell, and a bent air channel is formed between the adjacent partition boards; the shell is provided with a slit communicated with the air channel, and the cylinder is provided with a strip-shaped opening along the axial direction. The utility model discloses a resonator increases air duct's length through setting up crisscross baffle from top to bottom, changes the length of neck pipe promptly to change the resonant frequency of helmholtz resonator, and then realize the purpose of frequency adjustable.
Description
Technical Field
The utility model belongs to the technical field of noise control, in particular to helmholtz resonator that can frequency modulation.
Background
A helmholtz resonator is a basic acoustic unit consisting of a closed resonance chamber and a connected neck. When sound waves are incident, the air in the neck tube can be regarded as a mass to vibrate integrally, and the air in the closed cavity is subjected to expansion and contraction changes due to the vibration of the air in the neck tube, so that the Helmholtz resonator can be regarded as a spring-mass system with a damping term. When the incident frequency of the sound wave reaches the natural frequency of the system, the resonator resonates, and the sound absorption effect is good. Helmholtz resonators are widely used in duct muffling systems and in architectural acoustic structures because of their simple structure.
For the Helmholtz resonator, the sound absorption frequency depends on the volume of the closed cavity, the length of the neck pipe and the cross-sectional area of the neck pipe, when the parameters are determined, the resonance frequency is determined, the resonance frequency cannot be changed along with the change of the excitation frequency and the environmental conditions, the resonance frequency band is narrow, and when the excitation frequency is changed, the noise reduction effect is greatly reduced.
In order to obtain sound absorption with variable frequency, measures such as adjusting the volume of the closed cavity, changing the length of the neck pipe, changing the cross-sectional area of the neck pipe and the like can be taken. In general, due to the limitation of using space, it is difficult to freely change the volume of the resonant cavity in practical situations, especially in situations where low frequency noise reduction is to be achieved. While at the same time, changing the neck characteristics of the resonator is easier to handle and also enables the resonant frequency and resonant sound absorption coefficient to be changed simultaneously.
At present, there is also a structure for changing the resonance frequency and the resonance sound absorption coefficient by changing the neck characteristics of the resonator, but the length of the neck is limited, the width of the sound absorption frequency is limited, and sound absorption of a wide range of frequencies cannot be realized, so that a sound absorption structure with a wider frequency modulation width is required.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem, the utility model provides a helmholtz resonator of adjustable frequency to reach the length that increases air duct through setting up crisscross baffle from top to bottom, change the length of neck promptly, thereby change the resonant frequency of helmholtz resonator, and then realize frequency adjustable purpose.
In order to achieve the above purpose, the technical scheme of the utility model is as follows:
a frequency-adjustable Helmholtz resonator comprises a shell, wherein a cylindrical cavity is horizontally arranged in the shell, a rotatable cylinder is arranged in the center of the cylindrical cavity, one end of the cylinder extends out of the shell, and a knob is fixed at the end of the cylinder; the top end of the partition board positioned on the upper layer is in close contact with the inner wall of the cylindrical cavity, the bottom end of the partition board positioned on the lower layer is in close contact with the outer wall of the cylinder, the front end and the rear end of the partition board are fixed on the shell, and a bent air channel is formed between the adjacent partition boards; the shell is provided with a slit communicated with the air channel, and the cylinder is provided with a strip-shaped opening along the axial direction; the top end of a partition plate positioned on one side of the slit is in close contact with the inner wall of the cylindrical cavity, and the bottom end of the partition plate is in close contact with the outer wall of the cylinder.
In the above scheme, the shell is a cube or a cuboid.
In the above aspect, the length of the slit is not greater than the length of the cylinder, and the width of the slit is not greater than the distance between adjacent partitions.
In a further technical scheme, 50 partition plates are arranged on the upper layer, and 50 partition plates are arranged on the lower layer.
Through the technical scheme, the utility model provides a pair of helmholtz resonator of adjustable frequency has following beneficial effect:
the utility model discloses utilize the sound wave to be the scalar, can freely propagate this characteristic in crooked air duct, crooked along sound wave incident direction with the neck pipe of Helmholtz resonator to change air duct's length through setting up crisscross baffle from top to bottom, change the length of neck pipe promptly, thereby change the resonant frequency of Helmholtz resonator, and then realize that the frequency is adjustable. The utility model discloses under the condition that does not increase the casing volume, effectively utilize spatial structure, reached the purpose of making an uproar that falls in the low frequency.
Drawings
In order to clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below.
Fig. 1 is a schematic diagram of a frequency-tunable helmholtz resonator according to an embodiment of the present invention;
fig. 2 is a schematic cross-sectional view of a frequency-tunable helmholtz resonator according to an embodiment of the present invention.
In the figure, 1, a housing; 2. a cylindrical cavity; 3. a cylinder; 4. a knob; 5. a partition plate; 6. an air channel; 7. a slit; 8. and (5) opening the strip shape.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
The utility model provides a helmholtz resonator of adjustable frequency, as shown in fig. 1, including casing 1, in this embodiment, casing 1 is the cuboid.
A cylindrical cavity 2 is horizontally arranged inside the shell 1, a rotatable cylinder 3 is arranged at the center of the cylindrical cavity 2, one end of the cylinder 3 extends out of the shell 1, a knob 4 is fixed at the end of the cylinder 3, and the cylinder 3 can be driven to rotate by rotating the knob 4.
As shown in fig. 2, the partition boards 5 are staggered up and down in the cylindrical cavity 2 outside the cylinder 3, the top end of the partition board 5 on the upper layer is in close contact with the inner wall of the cylindrical cavity 2, the bottom end of the partition board 5 on the lower layer is in close contact with the outer wall of the cylinder 3, the front end and the rear end of each partition board 5 are fixed on the shell 1, and a curved air channel 6 is formed between the adjacent partition boards 5.
A slit 7 communicated with the air channel 6 is formed in the shell 1, and external noise can enter the resonator through the slit 7; the cylinder 3 is provided with a strip-shaped opening 8 along the axial direction, and noise entering the air passage 6 can enter the cylinder 3 through the strip-shaped opening 8. A partition a located on one side of the slit 7 has a top end closely contacting the inner wall of the cylindrical cavity 2 and a bottom end closely contacting the outer wall of the cylinder 3, which ensures that the noise coming from the slit 7 can propagate in the air passage 6 only in one direction.
In this embodiment, the length of the slit 7 is not greater than the length of the cylinder 3, and the width of the slit 7 is not greater than the distance between adjacent partitions 5. In this embodiment, there are 50 separators located in the upper layer, and 50 separators located in the lower layer.
The working principle of the resonator is as follows:
noise enters the air channel 6 from the slit 7 on the shell 1, bypasses the partition plate 5, is transmitted in the bent air channel 6, reaches the strip-shaped opening 8 on the round through, enters the cylinder 3, and achieves the sound absorption effect. The cylinder 3 can be driven to rotate by rotating the knob 4 outside the shell 1, so that the transmission distance of noise in the air channel 6 is changed, and the purpose of adjusting the frequency is achieved.
The cylinder 3 is rotated to change the length of the neck, and the equivalent length calculation formula of the length l of the neck is as follows:
wherein, alpha is the rotation angle, the length of l will change along with the change of the rotation angle, and h is the depth of the slit.
Wherein, C 0 As the acoustic velocity of the background medium, S 0 Is the cross-sectional area of the neck tube, d is the width of the neck tube, and V is the volume of the closed cavity.
The outer diameter r =30mm of the cylinder 3; the outer diameter R =65mm, the axial length 80mm, the depth h =5mm of the slit 7 at the sound wave inlet, the axial length 80mm, the width d =3mm, the wall thickness t =2mm of the cylinder 3, and the cross-sectional area S of the neck tube 0 ＝3×80mm 2 When cylinder 3 is rotated, the sound absorption coefficient can be measured by the standing wave tube method, cylinder 3 can be rotated by 0 ° to 360 ° at different rotation angles, the adjustable resonance frequency of the helmholtz resonator is 36.63Hz to 788.28Hz, when α =0, the resonance frequency of the helmholtz resonator is 788.28Hz, and when α =2 π, the resonance frequency of the helmholtz resonator is 36.63Hz, which enables a wide range of frequency adjustment.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (4)
1. A frequency-adjustable Helmholtz resonator comprises a shell, and is characterized in that a cylindrical cavity is horizontally arranged in the shell, a rotatable cylinder is arranged in the center of the cylindrical cavity, one end of the cylinder extends out of the shell, and a knob is fixed at the end of the cylinder; the top end of the partition board positioned on the upper layer is in close contact with the inner wall of the cylindrical cavity, the bottom end of the partition board positioned on the lower layer is in close contact with the outer wall of the cylinder, the front end and the rear end of the partition board are fixed on the shell, and a bent air channel is formed between the adjacent partition boards; the shell is provided with a slit communicated with the air channel, and the cylinder is provided with a strip-shaped opening along the axial direction; the top end of a partition board positioned on one side of the slit is in close contact with the inner wall of the cylindrical cavity, and the bottom end of the partition board is in close contact with the outer wall of the cylinder.
2. A helmholtz resonator according to claim 1, wherein the housing is square or rectangular.
3. A frequency tunable helmholtz resonator according to claim 1, wherein the length of said slit is not greater than the length of said cylinder and the width of said slit is not greater than the distance between adjacent baffles.
4. A frequency tunable helmholtz resonator according to claim 1, wherein there are 50 baffles in the upper layer and 50 baffles in the lower layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220509920.6U CN217606549U (en) | 2022-03-09 | 2022-03-09 | Frequency-adjustable Helmholtz resonator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220509920.6U CN217606549U (en) | 2022-03-09 | 2022-03-09 | Frequency-adjustable Helmholtz resonator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN217606549U true CN217606549U (en) | 2022-10-18 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202220509920.6U Active CN217606549U (en) | 2022-03-09 | 2022-03-09 | Frequency-adjustable Helmholtz resonator |
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|---|---|
| CN (1) | CN217606549U (en) |
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- 2022-03-09 CN CN202220509920.6U patent/CN217606549U/en active Active
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