WO2018094959A1

WO2018094959A1 - Helmholtz resonance muffling unit based on labyrinth structure, and resonance muffler

Info

Publication number: WO2018094959A1
Application number: PCT/CN2017/081098
Authority: WO
Inventors: 赖耘; 刘晨凯
Original assignee: 苏州大学张家港工业技术研究院
Priority date: 2016-11-22
Filing date: 2017-04-19
Publication date: 2018-05-31
Also published as: CN106382432A

Abstract

A Helmholtz resonance muffling unit based on a labyrinth structure, and a resonance muffler. The Helmholtz resonance muffling unit based on a labyrinth structure comprises a pipe body (1), a connection tube (3) connected to the pipe body (1), and a labyrinth cavity (4) which is in communication with the connection tube (3), a sound wave incident end of the labyrinth cavity (4) being in communication with the connection tube; the resonance cavity structure can lower the phonon forbidden band height, and can eliminate wide and low frequency noise while occupying a smaller space volume compared to a traditional Helmholtz resonance cavity. The resonance muffler (6) comprises a Helmholtz resonance muffling unit based on a labyrinth structure.

Description

Helmholtz resonance muffling unit and resonance muffler based on labyrinth structure

Technical field

The invention relates to the field of noise control, in particular to a Helmholtz resonance muffling unit and a resonance muffler based on a labyrinth structure.

Background technique

Pipeline systems have a wide range of applications in the fields of shipbuilding, water conservancy, chemical engineering, and aerospace. Noise propagation and noise control in the pipeline is a very important research content. The noise in the duct has low frequency characteristics caused by reciprocating or rotating motion of a fan or pump in the duct. The traditional Helmholtz resonator has a Helmholtz resonator, and by setting the structural parameters of the Helmholtz resonator, the problem of large noise in the pipeline can be solved. The reason is that when the sound wave reaches the Helmholtz resonance cavity, the sound wave cannot continue to propagate due to the change of the acoustic impedance at the junction, and the sound wave is completely reflected back at a certain frequency.

1 shows a schematic structural view of a conventional Helmholtz resonator including a pipe body 1, a Helmholtz cavity structure 2, and a connecting pipe 3. The pipe body 1 is in communication with the connecting pipe 3, and the connecting pipe 3 is in communication with the Helmholtz resonant cavity 2. Among them, the Helmholtz resonant cavity 2 is a rectangular cavity. According to the classical lumped parameter theory, the resonant frequency of a Helmholtz resonator:

Where: c ₀ is the speed of sound; V is the volume of the cavity; L is the length of the connecting pipe; S is the cross-sectional area of the connecting pipe; δ is the acoustic end correction. The main parameters of the Helmholtz resonator structure are the pipe body diameter, the diameter of the connecting pipe, the length of the connecting pipe and the volume of the cavity. The purpose of eliminating noise at a specific frequency can be achieved by changing these parameters. It can be known from the formula that if the resonance frequency is to be reduced, the cavity volume or the length of the connecting pipe must be increased, but the piping system of each precision field is compactly arranged and the size control is strict. Therefore, it is particularly important to reduce the resonance frequency without increasing the cavity volume and the length of the connecting tube, or to reduce the volume of the cavity and the length of the connecting tube while maintaining the resonant frequency.

Summary of the invention

The inventor of the present application has found that for the conventional Helmholtz resonator shown in Fig. 1, if the length of the pipe body is 0.3 m and the width is 0.02 m, the structure of the Helmholtz cavity is 0.2 m long and 0.236 m wide. The connecting tube is 0.02 meters long and 0.03 meters wide, and the Helmholtz resonant cavity structure is used as a repeating unit. After several cycles are connected in any direction via the pipe body, the simulation of the simulation software COMSOL Multiphysics will obtain the change of the transmittance of the Helmholtz resonator shown in Fig. 2 with the sound wave. As shown in Fig. 2, the scatter plot of the black triangle represents the change of the reflectance with the frequency of the sound wave, and the scatter plot of the gray star represents the change of the transmittance with the frequency of the sound wave. The smaller the transmittance (the higher the reflectance), the more the noise loss is, and the better the noise is eliminated. As can be seen from Fig. 2, the conventional Helmholtz resonator effectively eliminates noise in the wide frequency range of 100 Hz to 360 Hz. However, in the field of precision control, the piping system is compact and the size control is strict. The noise has low frequency characteristics and requires a small volume of Helmholtz resonator. However, as shown in Fig. 2, the conventional Helmholtz resonator It is difficult to achieve low frequency noise reduction under the limitation of small volume.

It is an object of the present invention to provide a Helmholtz resonance muffling unit and a resonance muffler based on a labyrinth structure for solving the problem that the conventional Helmholtz resonator cannot satisfy the low frequency noise cancellation.

In particular, the present invention provides a Helmholtz resonance muffling unit based on a labyrinth structure for eliminating noise, including:

Pipe body

a connecting pipe in communication with the pipe body; and

a labyrinth cavity in communication with the connecting tube for resonating with sound waves transmitted from the pipe body in an incident direction to completely eliminate sound waves in a transmission direction corresponding to the incident direction at certain frequencies .

Further, the labyrinth cavity is configured to be arranged in a zigzag parallel manner by a plurality of pipes.

Further, the plurality of pipes include:

An auxiliary duct communicating with the connecting pipe and extending in any initial direction for receiving sound waves transmitted from the pipe body along the connecting pipe;

A plurality of main pipes, one of the plurality of main pipes being in communication with the auxiliary pipe, the plurality of main pipes being for resonating with sound waves transmitted from the auxiliary pipe.

Further, the plurality of main pipes are equal in length.

Further, the labyrinth cavity is a semi-closed structure.

Further, the pipe body, the connecting pipe and the labyrinth cavity are prepared from a hard boundary material;

Optionally, the pipe body, the connecting pipe and the labyrinth cavity are made of the same hard boundary The material is prepared.

Further, the hard boundary material refers to a rigid boundary material, and the normal sound pressure of the incident sound wave at the boundary of the rigid boundary material is zero.

In particular, the present invention also provides a resonance muffler comprising the above-described labyrinth structure based Helmholtz resonance muffling unit.

Further, the labyrinth cavity has a main axis of the pipe body, and is wound around the pipe body in a parallel spiral manner from a position communicating with the connecting pipe to form a spiral pipe.

Further, the axial pitch of the spiral pipe is equal, and the radial pitch is zero;

Optionally, the pipe body, the connecting pipe and the spiral pipe are made of a plastic material.

The Helmholtz resonance muffling unit based on the labyrinth structure of the invention reduces the phonon forbidden band height by adopting the labyrinth structure resonance cavity. Compared with the conventional Helmholtz resonator, the Helmholtz resonance muffling unit of the present invention achieves lower frequency noise reduction in the case of the same occupied volume. In other words, the Helmholtz resonance muffling unit of the present invention achieves a reduction in cavity volume while maintaining a constant muffling frequency. Therefore, the solution of the invention can realize the elimination of the same frequency noise with a smaller volume of the resonant cavity, or can eliminate the lower frequency noise in the case of the same volume as the resonant cavity, and meet the requirements of the small volume of the precision instrument. . In addition, in the labyrinth cavity of the present invention, the more the number of turns of the meandering, the lower the corresponding noise frequency, so that the ultra-low frequency noise can be effectively suppressed.

Further, in the resonance muffler of the present invention, the labyrinth cavity is wound in a parallel spiral manner around the pipe body to form a spiral pipe, which occupies a small volume and can eliminate noise of a lower frequency. In addition, the maze structure material has wide selection, simple manufacture, low cost, convenient assembly, and wide application prospect.

The above as well as other objects, advantages and features of the present invention will become apparent to those skilled in the <

DRAWINGS

The background art and some specific embodiments of the present invention are described in detail, by way of example The same reference numbers in the drawings identify the same or similar parts. Those skilled in the art should understand that the drawings are not necessarily drawn to scale. In the figure:

Figure 1 is a schematic structural view of a conventional Helmholtz resonant cavity;

Figure 2 is a graph showing the transmittance and reflectance of a conventional Helmholtz resonator according to the acoustic wave frequency of Figure 1. Schematic diagram of the change;

3 is a schematic structural view of a Helmholtz resonance muffling unit based on a labyrinth structure according to an embodiment of the present invention;

4 is a schematic diagram showing changes in transmittance and reflectance of a Helmholtz resonator according to the labyrinth structure according to the sound wave frequency;

Figure 5 is a schematic perspective view of a resonance muffler in accordance with another embodiment of the present invention;

6 is a schematic diagram showing changes in transmittance and reflectance of a Helmholtz resonator of the resonance muffler of FIG. 5 as a function of sound wave frequency.

detailed description

3 shows a schematic structural view of a Helmholtz resonance muffling unit based on a labyrinth structure for noise cancellation of a pipe according to an embodiment of the present invention. In order to compare the Helmholtz resonance muffling unit of the present application with the noise canceling effect of the conventional Helmholtz resonant cavity, the Helmholtz resonance muffling unit of the present application is adopted with the traditional Helmhol The pipe body 1 and the connecting pipe 3 have the same resonant cavity, wherein the connecting pipe 3 is in communication with the pipe body 1. The Helmholtz resonance muffling unit further includes a labyrinth cavity 4 communicating with the connecting pipe 3 for resonating with sound waves transmitted from the pipe body 1 in the incident direction to be completely at some frequencies Acoustic waves in the transmission direction corresponding to the incident direction are eliminated.

As shown in FIG. 3, the labyrinth cavity 4 is configured to be arranged in a zigzag parallel manner by a plurality of ducts. The plurality of pipes includes an auxiliary pipe and a plurality of main pipes. The auxiliary duct communicates with the connecting pipe 3 and extends in any initial direction as an acoustic wave incident end of the labyrinth cavity 4 for receiving sound waves transmitted from the pipe body 1 along the connecting pipe 3. One of the plurality of main pipes is in communication with the auxiliary pipe. The plurality of main conduits are for resonating with sound waves transmitted from the auxiliary conduit. In the embodiment shown in Figure 3, the auxiliary duct extends from the connecting pipe 3 in a direction parallel to the pipe body 1, the plurality of main pipes being parallel to the auxiliary pipe, and the plurality of main pipes being of equal length. The acoustic wave incident end of the labyrinth cavity 4 communicates with the connecting pipe 3 to form a semi-closed structure. Compared with the conventional Helmholtz resonator, the structure of the labyrinth cavity 4 of the present invention can reduce the phonon forbidden band height, wherein the phonon band gap height corresponds to the elimination of the noise frequency. Therefore, the solution of the invention can realize the elimination of the same frequency noise with a smaller volume of the resonant cavity, or can eliminate the lower frequency noise in the case of the same volume as the resonant cavity, and meet the requirements of the small volume of the precision instrument. . In addition, in the labyrinth cavity of the present invention, the more the number of turns extended by the meandering, the corresponding noise frequency The lower the rate, the more effective it is to suppress ultra low frequency noise.

In order to verify that the Helmholtz resonance muffling unit of the present invention has the above-mentioned advantageous effects, in one embodiment, the labyrinth cavity 4 is 0.2 m long and 0.236 m wide, and the labyrinth cavity 4 is a straight pipe with a width of 0.02 m. Arranged in parallel in any initial direction in a meandering manner. The acoustic wave incident end of the labyrinth cavity 4 is in communication with the connecting pipe 3. FIG. 4 is a schematic diagram showing the variation of the transmittance and the reflectance with the frequency of the acoustic wave after the Helmholtz resonant cavity 1 based on the labyrinth structure is connected periodically in any direction. As shown in Fig. 4, the black triangle scatter plot shows the reflectance as a function of the sound wave frequency, and the gray star scatter plot shows the change of the transmittance as a function of the sound wave frequency. Among them, the smaller the transmittance (the higher the reflectance), the more the noise loss is, and the better the noise is eliminated. As can be seen from Fig. 4, the transmittance achieves an almost perfect silencing effect in the wide frequency range of 48 Hz to 80 Hz. The Helmholtz resonator of the present application greatly reduces the frequency at which noise can be eliminated compared to a conventional Helmholtz resonator of the same volume. It is thus shown that the labyrinth structure-based Helmholtz resonator of the present invention can achieve lower frequency noise cancellation while maintaining the same occupied volume of the resonant cavity. In other words, the present invention can reduce the space occupied by the resonant cavity while maintaining a specific muffling frequency.

The pipe body 1, the connecting pipe 3, and the labyrinth cavity 4 are prepared using a hard boundary material. The hard boundary material refers to a rigid boundary material, and the normal sound pressure of the incident sound wave at the boundary of the rigid boundary material is zero. In one embodiment, the pipe body 1, the connecting pipe 3, and the labyrinth cavity 4 are fabricated using the same hard boundary material. In one embodiment, the hard boundary material, ie, the rigid boundary material, is a plastic material, such as ABS plastic. Therefore, the labyrinth structure material is widely selected, simple to manufacture, low in cost, and easy to assemble.

Figure 5 shows a resonant muffler 6 machined in accordance with one embodiment of the present invention. As shown in FIG. 5, the resonance muffler 6 includes a Helmholtz resonance muffling unit based on a labyrinth structure. The Helmholtz resonance muffling unit based on the labyrinth structure has the same structure as the Helmholtz resonance muffling unit based on the labyrinth structure in the above embodiment. Therefore, the resonance muffler has the same advantageous effects as the above-described Helmholtz resonance muffling unit based on the labyrinth structure, and will not be described herein.

In the embodiment shown in Fig. 5, the labyrinth cavity 4 is wound around the pipe body 1 in a parallel spiral manner from the point where the pipe body 1 is in communication with the pipe body 1 to form the spiral pipe 5. The axial pitches of the spiral ducts 5 are kept equal. In one embodiment, the spiral conduit 5 has a length of 0.025 meters, a number of turns of 7, and a radial pitch of zero. This further reduces the space occupied by the space. FIG. 6 is a schematic diagram showing the variation of the transmittance and the reflectance with the frequency of the acoustic wave after the resonant muffler 6 is periodically connected in any direction via the pipe body 1. As shown in Figure 6, the black triangle is scattered The dot plot shows the reflectance as a function of the acoustic frequency, and the gray star scatter plot shows the plot of the transmittance as a function of the acoustic frequency. Among them, the smaller the transmittance, the more the noise loss is, and the better the noise is eliminated. It can be seen from Fig. 6 that the transmittance also achieves almost perfect noise cancellation in the wide frequency range of 48 Hz to 80 Hz, and the noise reduction frequency can be greatly reduced compared with the conventional Helmholtz resonance cavity of the same volume, and greatly Reduce the space occupied by the volume, to meet the requirements of small size preparation of various precision instruments. In addition, the pipe body 1, the connecting pipe 3 and the spiral pipe 5 are prepared from ordinary plastics, for example, still made of ABS plastic, so that the material of the resonant muffler 6 is widely selected, simple to manufacture, low in cost and easy to assemble.

In this regard, it will be appreciated by those skilled in the <RTIgt;the</RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; The content directly determines or derives many other variations or modifications consistent with the principles of the invention. Therefore, the scope of the invention should be understood and construed as covering all such other modifications or modifications.

Claims

A Helmholtz resonance muffling unit based on a maze structure for eliminating noise, including:

Pipe body

a connecting pipe in communication with the pipe body; and

a labyrinth cavity in communication with the connecting tube for resonating with sound waves transmitted from the pipe body in an incident direction to completely eliminate sound waves in a transmission direction corresponding to the incident direction at certain frequencies .
The labyrinth structure-based Helmholtz resonance muffling unit according to claim 1, wherein the labyrinth cavity is configured to be arranged in a zigzag parallel manner by a plurality of ducts.
The labyrinth structure-based Helmholtz resonance muffling unit according to claim 2, wherein the plurality of pipes comprise:

An auxiliary duct communicating with the connecting pipe and extending in any initial direction for receiving sound waves transmitted from the pipe body along the connecting pipe;

A plurality of main pipes, one of the plurality of main pipes being in communication with the auxiliary pipe, the plurality of main pipes being for resonating with sound waves transmitted from the auxiliary pipe.
The labyrinth structure-based Helmholtz resonance muffling unit according to claim 3, wherein the plurality of main pipes are equal in length.
The labyrinth structure-based Helmholtz resonance muffling unit according to claim 1, wherein the labyrinth cavity is a semi-closed structure.
The labyrinth structure-based Helmholtz resonance muffling unit according to any one of claims 1 to 5, wherein the duct body, the connecting pipe and the labyrinth cavity are made of a hard boundary material Prepared

Optionally, the duct body, the connecting tube and the labyrinth cavity are prepared from the same hard boundary material.
The Helmholtz resonance muffling unit based on the labyrinth structure according to claim 6, wherein the hard boundary material refers to a rigid boundary material, and the normal sound pressure of the incident acoustic wave at the boundary of the rigid boundary material Zero.
A resonance muffler comprising the Helmholtz resonance muffling unit based on the labyrinth structure according to any one of claims 1-7.
The resonance muffler according to claim 8, wherein the labyrinth cavity is wound in a parallel spiral manner from a position communicating with the connecting pipe with the pipe body as a main axis. Around the pipe body to form a spiral pipe.
A resonance muffler according to claim 9, wherein said spiral conduits have equal axial pitches and a radial pitch of zero;

Optionally, the pipe body, the connecting pipe and the spiral pipe are made of a plastic material.