Railway noise control method and device based on Helmholtz resonance

Abstract

The invention relates to the technical field of railway vibration and noise reduction, in particular to a railway noise control method and device based on Helmholtz resonance. Comprising the following steps: S1, establishing a Helmholtz resonance sound absorber simulation model, and verifying the effectiveness of the Helmholtz resonance sound absorber simulation model to obtain a simulation tool which can be used for structural design; s2, analyzing sound transmission loss frequency characteristics of different resonant cavity shapes and multi-unit arrangement modes based on the simulation model, and obtaining an influence rule of the sound transmission loss frequency characteristics on sound transmission loss; s3, obtaining the noise frequency characteristics of the target line under the normal working condition through a test or simulation, and determining a target noise control frequency band according to the noise frequency characteristics; and S4, designing the Helmholtz resonance sound absorption structure by using the simulation model according to the rule and the target frequency band. According to the method, the simulation model is established and verified, the structure rule is extracted, design and verification are carried out in combination with the target frequency band, and efficient noise reduction control for the railway noise specific frequency band is achieved.

Description

Technical Field

[0001] This invention relates to the field of railway vibration reduction and noise reduction technology, and in particular to a railway noise control method and device based on Helmholtz resonance. Background Technology

[0002] Currently, railways, with their speed, convenience, and large transport capacity, have become one of the main modes of transportation in my country's rapid development. However, the noise generated during railway operation can adversely affect the environment along the line, reducing the comfort of workers and residents, and even causing health problems. Therefore, railway noise control has always been a research hotspot in railway engineering. Existing technologies mainly address noise sources and propagation paths. For example, measures such as using embedded tracks, damped rails, rail dynamic vibration absorbers, heavy-duty rails, and seamless rails can reduce wheel-rail noise, or sound barriers can be installed to block or absorb train noise and reduce its propagation to the surrounding area. Although these measures have improved the noise environment along railway lines to some extent, their noise reduction effects are still limited. Helmholtz resonant sound absorption, as a new noise reduction principle, has advantages such as flexible and adjustable noise reduction frequency, significant peak noise reduction, simple structure, and low maintenance costs. However, research and application of this principle in railway vibration reduction and noise control are still limited, especially in the areas of combining Helmholtz resonators with dynamic vibration absorbers to control rail vibration noise, and combining them with sound barriers to control rail noise propagation. Therefore, there is an urgent need to propose a control method and device that can utilize the Helmholtz resonance sound absorption principle combined with the characteristics of railway noise to effectively reduce noise at specific frequencies, thereby overcoming the shortcomings of existing technologies in terms of flexibility, targeting, and noise reduction effectiveness. Summary of the Invention

[0003] This application aims to address at least one of the technical problems existing in the prior art by proposing a railway noise control method and device based on Helmholtz resonance. Through simulation models, the influence of adjusting the cavity geometric parameters (such as aspect ratio and diameter-to-height ratio) and the unit arrangement (parallel or series) on the resonant frequency and peak transmission loss is clarified. This allows the acquisition of the target noise reduction frequency corresponding to the corresponding structural parameters. Furthermore, the structural design is carried out in conjunction with the spectral characteristics of railway noise, thereby achieving effective control of the target noise frequency band and compensating for the shortcomings of existing railway noise reduction methods in terms of flexibility, specificity, and noise reduction effect.

[0004] In a first aspect, embodiments of this application provide a railway noise control method based on Helmholtz resonance, which may include: S1. Establish a simulation model of the Helmholtz resonant sound absorber, and verify the effectiveness of the simulation model by comparing it with the calculation results or experimental results, thereby obtaining simulation tools that can be used for structural design; S2. Based on the simulation model, analyze the frequency characteristics of transmission loss for different resonant cavity shapes and multiple resonant sound-absorbing unit arrangements, and obtain the influence of the shape parameters and arrangement on the transmission loss. S3. Obtain the noise frequency characteristics of the target railway line under normal operating conditions through experiments or simulations, and determine the target noise control frequency band based on the frequency characteristics; S4. Based on the influence law and the target noise control frequency band, the Helmholtz resonant sound absorption structure is designed using the simulation model to determine the resonant cavity shape, size, and unit arrangement that meet the noise reduction requirements of the target frequency band.

[0005] The railway noise control method based on Helmholtz resonance according to the embodiments of this application has at least the following beneficial effects: The method of this application first establishes and verifies a simulation model of the Helmholtz resonant absorber to ensure that the simulation tools used can accurately reflect the transmission loss characteristics. Then, the simulation model is used to analyze different resonant cavity shapes and multi-unit arrangements, summarizing their influence on the transmission loss characteristics. Next, combined with the target railway line noise spectrum characteristics obtained from experiments or simulations, the target noise frequency band that needs to be controlled is determined. Finally, guided by the stated rules and the target frequency band, the design of the Helmholtz resonant sound-absorbing structure is completed by adjusting the cavity geometric parameters and unit arrangement. This method, by combining simulation analysis with parameter adjustment, enables designers to gradually achieve structural matching for specific frequency bands of railway noise, achieving adjustable noise reduction frequency, significant peak suppression, and overall noise reduction effects superior to traditional measures.

[0006] According to some embodiments of this application, the method further includes: S5. Verify the noise reduction effect of the designed Helmholtz resonant sound absorption device, and output the noise reduction effect evaluation result of the device in the target noise control frequency band.

[0007] According to some embodiments of this application, S2 includes: while keeping the volume of the resonant cavity constant, adjusting the aspect ratio of the bottom surface of the square cavity. As the aspect ratio of the bottom surface increases, the resonant frequency gradually shifts to a lower frequency, but the shift range is limited, thereby obtaining the variation law of the aspect ratio of the square cavity with the resonant frequency and the peak position of the transmission loss.

[0008] According to some embodiments of this application, S2 includes: adjusting the diameter-to-height ratio of the cylindrical cavity while keeping the resonant cavity volume constant. When the diameter-to-height ratio gradually increases, the resonant frequency shows a trend of first increasing and then decreasing. A diameter-to-height ratio that is too large or too small will cause the simulation results to deviate more from the formula calculation results. When the diameter-to-height ratio is in the range of 0.3 to 5, the resonant frequency is basically stable in the range of 496 to 500 Hz. Thus, the influence law of diameter-to-height ratio on resonant frequency and peak transmission loss is obtained.

[0009] According to some embodiments of this application, S2 includes: under the condition of keeping the volume of the resonant cavity unchanged, a spherical cavity structure is adopted. Simulation calculation results show that its resonant frequency is about 496 Hz and the peak transmission loss is about 50 dB, thereby obtaining the characteristic law of the spherical cavity for the resonant frequency and the peak transmission loss.

[0010] According to some embodiments of this application, S2 further includes: analyzing the series and parallel arrangements of multiple resonant sound-absorbing units, and obtaining the following rules based on the simulation model: When cavities of different volumes are arranged in parallel, multiple resonant attenuation peaks are formed within the target noise control frequency band, thereby achieving broadband noise reduction; When cavities of the same volume are arranged in parallel, the attenuation effect is enhanced at a single frequency point. When two or more cavities are arranged in series, distributed attenuation is formed at different frequency points.

[0011] Secondly, embodiments of this application provide a railway noise control device based on Helmholtz resonance, the device comprising: The modeling and verification module is used to build a simulation model of the Helmholtz resonant sound absorber and compare and verify its effectiveness in order to generate a simulation tool that can be used for structural design. The influence analysis module is used to analyze the transmission loss frequency characteristics of different resonant cavity shapes and multiple resonant sound-absorbing unit arrangements based on the simulation tool, so as to obtain the influence law of the shape parameters and arrangement on the transmission loss. The spectrum acquisition and target frequency band determination module is used to acquire the noise frequency characteristics of the target railway line and determine the target noise control frequency band based on the noise frequency characteristics. The structural design module is used to design a Helmholtz resonant sound-absorbing structure using the simulation tool based on the influence law and the target noise control frequency band, and to determine the shape, size and unit arrangement of the resonant cavity that meet the noise reduction requirements of the target frequency band.

[0012] The railway noise control device based on Helmholtz resonance according to the embodiments of this application has at least the following beneficial effects: The apparatus of this application embodiment first establishes and verifies a simulation model of the Helmholtz resonant sound absorber through a modeling and verification module, ensuring that the generated simulation tool can accurately reflect the acoustic characteristics. Then, an influence analysis module uses this simulation tool to analyze different resonant cavity shapes and unit arrangements to obtain their impact on sound transmission loss. Next, a spectrum acquisition and target frequency band determination module collects and processes the noise characteristics of the target railway line to identify the target frequency band that needs to be controlled. Finally, a structural design module, guided by the aforementioned patterns and target frequency band, completes the design of the Helmholtz resonant sound-absorbing structure by adjusting geometric parameters and unit arrangements. The apparatus, through the division of labor and collaboration among functional modules, provides designers with tools to adjust the structure and match the frequency, achieving flexible adaptation to the target frequency band, adjustable noise reduction frequency, significant peak suppression, and an overall noise reduction effect superior to traditional measures.

[0013] According to some embodiments of this application, it further includes: an effect verification module, used to verify the noise reduction effect of the Helmholtz resonant sound absorption device output by the structural design module, and output the noise reduction effect evaluation result of the device in the target noise control frequency band.

[0014] According to some embodiments of this application, the structural design module is configured to adjust the aspect ratio of the bottom surface of the square cavity, the diameter-to-height ratio of the cylindrical cavity, or to adopt a spherical cavity structure while keeping the volume of the resonant cavity constant, so as to adjust the resonant frequency and the peak position of the transmission loss.

[0015] According to some embodiments of this application, the railway noise control device is as follows: The rail resonant sound absorber is installed on the rail web and / or rail bottom and consists of multiple resonant sound absorbing units of different sizes arranged in parallel. Alternatively, the railway noise control device may be a trackside resonant sound-absorbing barrier, which includes a sound barrier frame and a Helmholtz resonant sound-absorbing panel disposed therein, wherein multiple Helmholtz resonant sound-absorbing units are regularly distributed within the panel.

[0016] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing this application. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the steps of the railway noise control method based on Helmholtz resonance in Embodiment 1 of this application. Figure 2 This is a schematic diagram of the basic unit of the Helmholtz resonant sound-absorbing structure in Embodiment 2 of this application; Figure 3This is a schematic diagram of the simulation model of the Helmholtz resonant sound absorber in Embodiment 2 of this application; Figure 4 This is a schematic diagram of the sound transmission loss of a single Helmholtz resonant absorber in Embodiment 2 of this application. Figure labels: (a) is a schematic diagram comparing the results of the prediction formula and the simulation model; (b) is a schematic diagram of the influence of the aspect ratio of the resonant cavity on the sound transmission loss; (c) is a schematic diagram of the influence of the spherical cavity on the sound transmission loss; (d) is a schematic diagram of the influence of the cylindrical cavity on the sound transmission loss. Figure 5 This diagram illustrates the impact of the arrangement of multiple Helmholtz resonant absorbers in an embodiment of this application on sound transmission loss. The attached figures are labeled as follows: (a) is a schematic diagram of three series connection methods, (b) is a schematic diagram of the impact of series connection method on sound transmission loss, (c) is a schematic diagram of three parallel connection methods, and (d) is a schematic diagram of the impact of parallel connection method on sound transmission loss. Figure 6 This is a schematic diagram of a rail resonant sound absorber designed based on the Helmholtz resonant sound absorption principle according to Embodiment 3 of this application. Figure labels: (a) Schematic diagram of Helmholtz rail resonant sound absorber, (b) Schematic diagram of the noise reduction effect of Helmholtz rail resonant sound absorber; Figure 7 This is a schematic diagram of a trackside sound-absorbing panel designed based on the Helmholtz resonance sound absorption principle in Embodiment 4 of this application. Attached figures: (a) Schematic diagram of Helmholtz trackside sound-absorbing panel; (b) Schematic diagram of the installation position of trackside sound-absorbing panel; (c) Schematic diagram of the noise reduction effect of trackside sound-absorbing panel. Figure 8 This is a structural block diagram of the railway noise control device based on Helmholtz resonance according to Embodiment 5 of this application. Detailed Implementation

[0018] The present application will now be described in further detail with reference to experimental examples and specific embodiments. However, this should not be construed as limiting the scope of the subject matter of the present application to the following embodiments. All technologies implemented based on the content of the present application fall within the scope of protection of the present application.

[0019] Unless otherwise specified, the terms "upper," "lower," "left," "right," "center," "inner," "outer," and "side" used in the description of specific embodiments of this application to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is usually placed during use. These terms are merely for the purpose of facilitating the description of the solution in this application or simplifying the description in specific embodiments, so as to enable those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on this application.

[0020] In the description of the embodiments of this application, technical terms such as "first" and "second" only distinguish one entity or operation from another, and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary or secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] Example 1 During the research process, the applicant discovered that when using existing noise reduction measures such as embedded tracks, damped rails, rail dynamic vibration absorbers, and sound barriers, effectively controlling specific frequency peak noise generated during railway operation requires complex structural designs or large-scale engineering measures. These procedures are cumbersome and struggle to balance noise reduction effectiveness with engineering applicability, only reducing noise within a limited range. In solving practical engineering problems, existing technologies clearly cannot meet the requirements for flexibly adjusting noise frequencies and effectively reducing peak noise. Therefore, after researching this issue, the applicant proposed a railway noise control method and device based on the Helmholtz resonance sound absorption principle. Addressing the technical problem of controlling specific peak frequencies concentrated in the mid-frequency band of railway noise, the applicant established and verified a simulation model of a Helmholtz resonance sound absorber, analyzed the influence of cavity shape and arrangement on sound transmission loss, and designed a suitable sound-absorbing structure based on the actual railway noise spectrum characteristics. This achieved effective control of rail and trackside noise, resulting in adjustable noise reduction frequency, significant peak attenuation, and improved noise environment along the railway line.

[0023] Please refer to Figure 1 , Figure 1 A schematic diagram illustrating the steps of a railway noise control method based on Helmholtz resonance provided in an embodiment of this application. The method may include: S1. Establish a simulation model of the Helmholtz resonant sound absorber, and verify the effectiveness of the simulation model by comparing it with the calculation results or experimental results, thereby obtaining simulation tools that can be used for structural design; S2. Based on the simulation model, analyze the frequency characteristics of transmission loss for different resonant cavity shapes and multiple resonant sound-absorbing unit arrangements, and obtain the influence of the shape parameters and arrangement on the transmission loss. S3. Obtain the noise frequency characteristics of the target railway line under normal operating conditions through experiments or simulations, and determine the target noise control frequency band based on the frequency characteristics; S4. Based on the influence law and the target noise control frequency band, the Helmholtz resonant sound absorption structure is designed using the simulation model to determine the resonant cavity shape, size, and unit arrangement that meet the noise reduction requirements of the target frequency band.

[0024] The railway noise control method based on Helmholtz resonance according to the embodiments of this application has at least the following beneficial effects: The method of this application first establishes and verifies a simulation model of the Helmholtz resonant absorber to ensure that the simulation tools used can accurately reflect the transmission loss characteristics. Then, the simulation model is used to analyze different resonant cavity shapes and multi-unit arrangements, summarizing their influence on the transmission loss characteristics. Next, combined with the target railway line noise spectrum characteristics obtained from experiments or simulations, the target noise frequency band that needs to be controlled is determined. Finally, guided by the stated rules and the target frequency band, the design of the Helmholtz resonant sound-absorbing structure is completed by adjusting the cavity geometric parameters and unit arrangement. This method, by combining simulation analysis with parameter adjustment, enables designers to gradually achieve structural matching for specific frequency bands of railway noise, achieving adjustable noise reduction frequency, significant peak suppression, and overall noise reduction effects superior to traditional measures.

[0025] According to some embodiments of this application, the method further includes: S5. Verify the noise reduction effect of the designed Helmholtz resonant sound absorption device, and output the noise reduction effect evaluation result of the device in the target noise control frequency band.

[0026] According to some embodiments of this application, S2 includes: while keeping the volume of the resonant cavity constant, adjusting the aspect ratio of the bottom surface of the square cavity. As the aspect ratio of the bottom surface increases, the resonant frequency gradually shifts to a lower frequency, but the shift range is limited, thereby obtaining the variation law of the aspect ratio of the square cavity with the resonant frequency and the peak position of the transmission loss.

[0027] According to some embodiments of this application, S2 includes: adjusting the diameter-to-height ratio of the cylindrical cavity while keeping the resonant cavity volume constant. When the diameter-to-height ratio gradually increases, the resonant frequency shows a trend of first increasing and then decreasing. A diameter-to-height ratio that is too large or too small will cause the simulation results to deviate more from the formula calculation results. When the diameter-to-height ratio is in the range of 0.3 to 5, the resonant frequency is basically stable in the range of 496 to 500 Hz. Thus, the influence law of diameter-to-height ratio on resonant frequency and peak transmission loss is obtained.

[0028] According to some embodiments of this application, S2 includes: under the condition of keeping the volume of the resonant cavity unchanged, a spherical cavity structure is adopted. Simulation calculation results show that its resonant frequency is about 496 Hz and the peak transmission loss is about 50 dB, thereby obtaining the characteristic law of the spherical cavity for the resonant frequency and the peak transmission loss.

[0029] According to some embodiments of this application, S2 further includes: analyzing the series and parallel arrangements of multiple resonant sound-absorbing units, and obtaining the following rules based on the simulation model: When cavities of different volumes are arranged in parallel, multiple resonant attenuation peaks are formed within the target noise control frequency band, thereby achieving broadband noise reduction; When cavities of the same volume are arranged in parallel, the attenuation effect is enhanced at a single frequency point. When two or more cavities are arranged in series, distributed attenuation is formed at different frequency points.

[0030] The railway noise control method based on Helmholtz resonance provided in this application can be applied to many technical fields, such as railway transportation, urban rail transit, and subway lines. In the above implementation, when controlling rail-radiated noise and trackside propagated noise, the noise spectrum characteristics of the operating line can be obtained, and the cavity shape and arrangement rules obtained by simulation model analysis can be flexibly designed to meet the target frequency band. Different sized sound-absorbing units can be arranged on the rail web and rail bottom to reduce rail-radiated noise, or multiple sound-absorbing units can be arranged in an array in the trackside sound barrier panel to weaken the noise propagating along the line. Through the above design and application, effective reduction of railway noise in the target frequency band is achieved, thereby achieving adjustable noise reduction frequency, significant peak suppression, and improved sound environment along the line.

[0031] Example 2 As a further optimization of the preceding embodiments, this application provides a specific implementation of a railway noise control method based on Helmholtz resonance.

[0032] First, based on a simple Helmholtz resonant sound-absorbing structure, its sound absorption and noise reduction principle is derived. The basic Helmholtz resonant sound-absorbing structure is as follows: Figure 2 As shown, it consists of a main pipe 1, a connecting pipe 2, and a resonant cavity 3. When the wavelength of the incident sound wave is much larger than the structural dimensions of the resonant cavity and connecting pipe, and the volume of the connecting pipe is much smaller than the volume of the resonant cavity, the air inside the neck can be considered as a whole with constant volume. The air inside the cavity is equivalent to a spring, forming a spring-mass system. The air in the connecting pipe is equivalent to a mass block with constant volume. The air inside the resonant cavity, under the action of external excitation, is equivalent to a spring with constant mass. The elastic coefficient k of the equivalent spring can be expressed as... (1) in, air density, The speed of sound in air. This represents the cross-sectional area of ​​the connecting pipe. The volume of the resonant cavity.

[0033] The system's natural frequency for (2) Transmission loss of a single-cavity resonator TL for (3) in, p i The fluctuation amount of the incident sound wave's sound pressure. p t This refers to the fluctuation amount of the sound pressure of the projected and transmitted sound waves. f Let be the frequency of the sound wave propagating in the pipe. The formula shows that the sound transmission loss of a single Helmholtz resonant sound-absorbing structure is related to the resonant cavity volume. The cross-sectional area of ​​the connecting pipe The cross-sectional area of ​​the supervisor and the length of the connecting pipe This is relevant. By designing the geometric parameters of the resonant cavity, connecting pipe, and main pipe, the resonant absorption frequency can be flexibly controlled. Furthermore, multiple resonant absorbers of different structural sizes can be arranged in series and parallel to achieve broadband noise reduction at multiple frequencies.

[0034] However, Formula 3 cannot calculate the transmission loss under conditions of varying resonant cavity shape and different resonator arrangements. Further, formulas such as... Figure 3The simulation model of a single Helmholtz resonant absorber shown is used to compare the simulated transmission loss results with the calculation results of Equation 3. The simulation model and the calculation use the same structural dimensions: the main pipe diameter is 10 mm, the length is 100 mm, and the resonator cavity is a cube with a volume of 9000 mm². 3 The connecting pipe has a diameter of 5 mm and a length of 21 mm. The sound transmission loss results for both are attached. Figure 4 As shown in (a), the simulated resonant frequency of the single-cavity resonant silencer is 502 Hz, and the peak transmission loss is 55 dB; the calculated resonant frequency is 505 Hz, and the peak transmission loss is 60 dB. The simulation results deviate slightly from the calculated results. The main reason for this difference is that the lumped parameter model is a one-dimensional model and cannot account for the influence of higher-order acoustic modes propagating at the cross-sectional changes of the connecting pipe. However, overall, the simulation results are basically consistent with the calculated results, and the error is within the acceptable range. Therefore, the simulation model will be used to design the cavity shape, resonator arrangement, etc.

[0035] Furthermore, based on the Helmholtz resonant absorber simulation model verified by the formula, the insertion loss of different cavity shapes (square cavity, spherical cavity, cylindrical cavity) is analyzed.

[0036] For square cavities, keeping the cavity volume and height constant, the influence of the cavity aspect ratio on a single Helmholtz resonant sound-absorbing structure is discussed. The results are attached. Figure 4 As shown in (b), when the cavity is square, the resonant frequency of the resonator gradually shifts to lower frequencies as the aspect ratio of the cavity bottom surface gradually increases. However, the change in the aspect ratio of the bottom surface has a relatively small effect on the resonant frequency.

[0037] Furthermore, for a single Helmholtz resonant sound-absorbing structure, keeping the cavity volume constant, the influence of the spherical cavity on the resonant frequency and transmission loss of the resonator is discussed. The results are attached. Figure 4 As shown in (c), when the cavity is spherical, the simulated resonant frequency is 496 Hz and the transmission loss is 50.6 dB.

[0038] Furthermore, for a single Helmholtz resonant sound-absorbing structure, keeping the cavity volume constant, the influence of the cavity's cylindrical diameter-to-height ratio on the resonator's resonant frequency and transmission loss is discussed. The results are as follows: Figure 4As shown in (d), when the cavity is cylindrical, the resonant frequency of the resonator tends to shift first to higher frequencies and then to lower frequencies as the cavity diameter-to-height ratio gradually increases. Both excessively large and small diameter-to-height ratios will cause significant deviations between the simulated and calculated resonant frequencies. When the diameter-to-height ratio varies within the range of 0.3 to 5, the simulated resonant frequency varies within the range of 496 to 500 Hz.

[0039] Furthermore, the influence of the resonator arrangement on the resonant frequency and transmission loss is discussed.

[0040] First, we discuss the impact of series connection of cavities, and design three series connection methods for cavities of different sizes, as shown in the attached diagram. Figure 5 As shown in (a), the volume ratio of the upper and lower cavities in models a, b, and c is... V 1: V The ratios of the cavities were 1:2, 1:1, and 2:1, with the sum of the volumes of the upper and lower cavities remaining constant, and the geometry of the connecting tube also unchanged. The effects of these different volume ratios on the resonant frequency and transmission loss were investigated. The results are attached. Figure 5 As shown in (b), when the two cavities are arranged in series, there are two resonant frequencies. As the volume of the upper cavity increases, the high-frequency resonant frequency of the muffler gradually shifts to a lower frequency, consistent with the rule that the resonant frequency of a single-cavity resonant muffler decreases as the volume of the resonant cavity increases. Simultaneously, the difference between the two resonant frequencies gradually decreases as the volume of the upper cavity increases. Regarding transmission loss, the transmission loss corresponding to the low-frequency resonant frequency is in the range of 35–55 dB, while the transmission loss corresponding to the high-frequency resonant frequency is in the range of 15–35 dB. The above analysis shows that this is because, with a fixed geometric dimension of the connecting tube, the effective cavity volume corresponding to the low-frequency resonant frequency is larger than that corresponding to the high-frequency resonant frequency, resulting in better noise reduction at the low-frequency resonant frequency. Therefore, in the structural design of a Helmholtz resonator, multiple cavities can be arranged in series to suppress noise at multiple frequencies.

[0041] Furthermore, the influence of parallel cavity arrangement on resonant frequency and transmission loss is discussed. Three parallel connection methods for cavities of different sizes are designed, as shown in the appendix. Figure 5 As shown in (c), the volume ratios V1:V2 of the left and right cavities in models a, b, and c are 1:1, 1:2, and 1:3, respectively, with the sum of the volumes of the left and right cavities remaining constant and the geometric dimensions of the connecting tube unchanged. The influence of parallel connection of cavities with different volume ratios on the resonant frequency and transmission loss is investigated. The results are attached. Figure 5As shown in (d), when two cavities are arranged in parallel, there are two resonant frequencies. When the two cavities have the same volume, the resonant frequencies coincide. When the volume of one resonator cavity increases, the corresponding resonant frequency also shifts to a lower frequency, which is consistent with the rule that the resonant frequency of a single-cavity resonant silencer decreases as the volume of the resonant cavity increases; and the difference between the two resonant frequencies also decreases as the difference in volume between the two cavities decreases. Regarding transmission loss, when the volumes of the two cavities are different, the transmission loss is in the range of 30~35 dB; when the volumes of the two cavities are the same, the transmission loss is the sum of the single-cavity resonant silencer. Therefore, in the structural design of Helmholtz resonators, the purpose of suppressing multiple frequency noises can be achieved by arranging cavities of different volumes in parallel, and the purpose of improving the silencing performance can be achieved by arranging cavities of the same volume in parallel.

[0042] By studying the influence of cavity geometry, resonator geometry parameters, and resonator arrangement on the sound transmission loss of the Helmholtz resonant sound absorption structure, we can understand the influence of these key parameters on the sound transmission loss of the Helmholtz resonant sound absorption structure and develop a design method for Helmholtz resonant sound absorption devices suitable for railways.

[0043] Furthermore, based on the proposed Helmholtz resonance-based railway noise control method, two Helmholtz resonance sound-absorbing structures are proposed for rail noise reduction and trackside sound-absorbing barriers, respectively, and their application effects in practical engineering scenarios are analyzed. This part is described in detail in the specific implementation plan.

[0044] In the embodiments of this application, the proposed method can take into account the sound absorption and noise reduction effect of the resonant cavity shape and size, the connecting pipe size, and the arrangement and combination of resonant sound absorbers in the Helmholtz resonant sound absorption structure.

[0045] In this embodiment, based on the proposed Helmholtz resonant sound-absorbing structure design method, noise reduction structures suitable for railway scenarios, such as rail sound absorption and trackside sound-absorbing panels, can be flexibly designed to achieve fixed-frequency and wide-band noise reduction for railways, effectively alleviating railway noise pollution problems. Simultaneously, due to the numerous small pipes within the trackside sound-absorbing panel structure, some train airflow can pass through these pipes, thereby reducing wind pressure and improving the wind resistance stability of the trackside sound barrier panel.

[0046] Example 3 As a further optimization of the preceding embodiments, this application provides a specific implementation of a railway noise control method based on Helmholtz resonance.

[0047] As attached Figure 6As shown in (a), a rail resonant sound absorber is designed based on the Helmholtz resonant sound-absorbing structure design method proposed in the embodiments of this application. It includes Helmholtz resonant sound-absorbing structures installed on the rail web and rail bottom. The Helmholtz rail resonant sound absorber is composed of multiple resonant sound-absorbing structures of different sizes arranged in parallel.

[0048] First, the radiated noise of the rails under normal operating speed conditions is analyzed to determine the main noise peak frequencies and identify the target frequency band for noise control. Taking a 60 km / h subway as an example, the rail radiated noise spectrum is shown in the attached figure. Figure 6 As shown in (b). (From the appendix) Figure 6 From (b), it can be seen that without rail noise reduction measures, the rail vibration radiated sound power is 103 dBA, the main noise frequency is the 1 / 3 octave band with the center frequency of 250~1250 Hz, and the noise peak is the 1 / 3 octave band with the center frequency of 800 Hz.

[0049] Furthermore, the target frequency band for rail noise control was determined to be 250~1250 Hz, with the key target being the 1 / 3 octave band of the center frequency at 800 Hz.

[0050] Furthermore, by applying the proposed Helmholtz resonant sound-absorbing structure design method, the shape, size, and arrangement of the Helmholtz resonant sound absorber that can meet the noise reduction requirements of the target frequency band are designed.

[0051] Specifically, based on the establishment and verification of the Helmholtz resonant sound absorber simulation model, this application further analyzes the influence of different cavity geometric parameters and multi-unit arrangement on the frequency characteristics of transmission loss. For example, while keeping the cavity volume constant, adjusting the aspect ratio of the bottom surface of a square cavity, the diameter-to-height ratio of a cylindrical cavity, or using a spherical cavity structure will all cause changes in the resonant frequency and the peak position of transmission loss. By arranging multiple resonant cavities in parallel or series, broadband attenuation, enhanced single-frequency attenuation, or distributed attenuation effects can be achieved, respectively. Based on the above principles, after performing spectral analysis on the target railway line noise and determining the target noise control frequency band, the cavity shape, size, and arrangement can be selected to match the peak frequency within the corresponding frequency band, thereby completing the targeted design of the Helmholtz resonant sound absorption structure. Therefore, this application not only proposes an overall design method but also provides the correspondence between structural parameters and frequency response, enabling those skilled in the art to complete the structural design and achieve the expected noise reduction effect.

[0052] Furthermore, the noise reduction effect of the designed Helmholtz resonant sound absorber on the rail was analyzed, and the results are attached. Figure 6As shown in (b), after installing the Helmholtz resonant sound absorbers designed in this application at the rail web and rail bottom, the rail radiated sound power is 95.2 dBA, which is 7.8 dBA lower than that without the Helmholtz resonant sound absorbers; within the 1 / 3 octave band with a center frequency of 250~1250 Hz, the rail radiated sound power level decreases by 8.3~15.3 dBA, with the largest decrease in sound power level at the 1 / 3 octave band with a center frequency of 800 Hz, where the rail radiated sound power level decreases by 15.3 dBA.

[0053] The method and the designed rail resonant sound absorber proposed in this application have a good rail noise control effect.

[0054] Example 4 As a further optimization of the preceding embodiments, this application provides a specific implementation of a railway noise control method based on Helmholtz resonance.

[0055] As attached Figure 7 As shown in (a), a trackside resonant sound-absorbing barrier is designed based on the Helmholtz resonant sound-absorbing structure design method proposed in the embodiments of this application. Figure 7 In (a), the three red circles represent progressively magnified images. This includes the sound barrier frame, Helmholtz resonant sound-absorbing panels, and a large number of Helmholtz resonant sound-absorbing units regularly distributed within the panels. (See attached image.) Figure 7 (b) is a schematic diagram of the installation position of the trackside sound-absorbing panel.

[0056] Using a point 7.5 m from the track centerline and 1.2 m above the track surface as the noise evaluation point along the track, the noise results under normal operating speed conditions were analyzed to determine the main noise peak frequencies and identify the target frequency band for noise control. Taking a 45 km / h urban rail transit system as an example, the noise spectrum along the line is shown in the attached figure. Figure 7 As shown in (c), without any noise control measures along the line, the noise level along the line is 86.8 dBA. The main frequency of the noise is in the 1 / 3 octave band with a center frequency of 200~1250 Hz, and the noise peak is in the 1 / 3 octave band with a center frequency of 315 Hz.

[0057] Furthermore, the target frequency band for noise control along the line was determined to be 200~1250 Hz, with the key target being the 1 / 3 octave band of the center frequency at 315 Hz.

[0058] Furthermore, by applying the proposed Helmholtz resonant sound-absorbing structure design method, the shape, size, and arrangement of the Helmholtz resonant sound absorber that can meet the noise reduction requirements of the target frequency band are designed.

[0059] Furthermore, the noise reduction effect of the designed trackside Helmholtz resonant sound-absorbing barrier was analyzed along the railway line, and the results are attached. Figure 7 As shown in (c), after installing the Helmholtz resonant sound-absorbing barrier designed in this embodiment of the application along the track, the noise level along the track is 74.0 dBA, which is 12.8 dBA lower than that without the Helmholtz resonant sound-absorbing barrier; within the 1 / 3 octave band with a center frequency of 200~1250 Hz, the noise level along the track is reduced by 7.6~35 dBA, with the largest reduction in sound pressure level at the 1 / 3 octave band with a center frequency of 315 Hz, where the noise sound pressure level along the track is reduced by 35.0 dBA.

[0060] The method and design of the trackside resonant sound-absorbing barrier proposed in this application have good noise control effects along the railway line. At the same time, due to the numerous small pipes inside the trackside sound-absorbing panel structure, some train air can pass through the pipes, thereby reducing wind pressure and improving the wind resistance stability of the trackside sound barrier panel.

[0061] Example 5 like Figure 8 As shown, this embodiment provides a railway noise control device based on Helmholtz resonance. The device includes: Modeling and Verification Module: This module is used to build a simulation model of the Helmholtz resonant sound absorber and verify the effectiveness of the simulation model by comparing it with calculation results or experimental results, thereby obtaining a simulation tool that can be used for subsequent design. Impact Analysis Module: Based on the simulation tool, this module analyzes the frequency characteristics of transmission loss of different resonant cavity shapes (such as square, spherical, cylindrical) and multi-unit arrangement methods (series, parallel), and obtains the influence of relevant structural parameters and arrangement methods on transmission loss. Spectrum acquisition and target frequency band determination module: used to collect the noise frequency characteristics of railway lines under normal operating conditions, and determine the target noise frequency band to be controlled, such as the range of 200 Hz to 1250 Hz. The structural design module is used to design the Helmholtz resonant sound absorption structure using the simulation tool based on the influence law and the target frequency band, determining the cavity shape, size, and unit arrangement. This module can generate structures with parallel arrangement of cavities of different volumes to form multiple attenuation peaks for broadband noise reduction, as well as structures with parallel arrangement of cavities of the same volume to enhance the attenuation effect at a single frequency point. It can also generate structures with multiple cavities arranged in series to form distributed attenuation at different frequency points. Effect verification module: used to analyze the noise reduction performance of the device output by the structural design module, and output the noise reduction effect evaluation results within the target frequency band.

[0062] In one specific embodiment, the railway noise control device is a rail resonant sound absorber, installed on the rail web and / or rail base, and composed of multiple resonant units of different sizes arranged in parallel to reduce rail radiated noise. Test results show that the device achieves significant noise reduction within the target frequency band, especially exhibiting significant sound power attenuation at the 800 Hz center frequency.

[0063] In another embodiment, the railway noise control device is a trackside resonant sound-absorbing barrier, which includes a sound barrier frame and regularly distributed Helmholtz resonant sound-absorbing panels, with multiple resonant units arranged in an array within the panels. This structure can not only significantly reduce noise along the railway line in the target frequency band of 200 Hz to 1250 Hz, but also reduce wind pressure and improve the wind resistance stability of the sound barrier through the internal pipe structure of the panels.

[0064] It should be understood that the various modules of the railway noise control device based on Helmholtz resonance provided in the above embodiments are only illustrated by the division of functional modules in the above description when performing noise control. In practical applications, the above functions can be assigned to different functional modules as needed. That is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0065] The functional modules in the above embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of the embodiments of this application.

[0066] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects.

[0067] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A railway noise control method based on Helmholtz resonance, characterized in that, include: S1. Establish a simulation model of the Helmholtz resonant sound absorber, and verify the effectiveness of the simulation model by comparing it with the calculation results or experimental results, thereby obtaining simulation tools that can be used for structural design; S2. Based on the simulation model, analyze the frequency characteristics of transmission loss for different resonant cavity shapes and multiple resonant sound-absorbing unit arrangements, and obtain the influence of the shape parameters and arrangement on the transmission loss. S3. Obtain the noise frequency characteristics of the target railway line under normal operating conditions through experiments or simulations, and determine the target noise control frequency band based on the frequency characteristics; S4. Based on the influence law and the target noise control frequency band, the Helmholtz resonant sound absorption structure is designed using the simulation model to determine the resonant cavity shape, size, and unit arrangement that meet the noise reduction requirements of the target frequency band.

2. The method according to claim 1, characterized in that, The method further includes: S5. Verify the noise reduction effect of the designed Helmholtz resonant sound absorption device, and output the noise reduction effect evaluation result of the device in the target noise control frequency band.

3. The method according to claim 1, characterized in that, S2 includes: while keeping the volume of the resonant cavity constant, adjusting the aspect ratio of the bottom surface of the square cavity. As the aspect ratio of the bottom surface increases, the resonant frequency gradually shifts to a lower frequency, but the shift range is limited, thereby obtaining the variation law of the aspect ratio of the square cavity with the resonant frequency and the peak position of the transmission loss.

4. The method according to claim 1, characterized in that, S2 includes: while keeping the volume of the resonant cavity constant, adjusting the diameter-to-height ratio of the cylindrical cavity. When the diameter-to-height ratio gradually increases, the resonant frequency shows a trend of first increasing and then decreasing. Both excessively large and excessively small diameter-to-height ratios will lead to an increase in the deviation between the simulation results and the formula calculation results. When the diameter-to-height ratio is in the range of 0.3 to 5, the resonant frequency is basically stable in the range of 496 to 500 Hz. Thus, the influence law of diameter-to-height ratio on resonant frequency and peak transmission loss is obtained.

5. The method according to claim 1, characterized in that, S2 includes: under the condition of keeping the volume of the resonant cavity unchanged, a spherical cavity structure is adopted. Simulation calculation results show that its resonant frequency is about 496 Hz and the peak transmission loss is about 50dB, thereby obtaining the characteristic law of the spherical cavity for the resonant frequency and the peak transmission loss.

6. The method according to claim 1, characterized in that, S2 further includes: analyzing the series and parallel arrangements of multiple resonant sound-absorbing units, and obtaining the following rules based on the simulation model: When cavities of different volumes are arranged in parallel, multiple resonant attenuation peaks are formed within the target noise control frequency band, thereby achieving broadband noise reduction; When cavities of the same volume are arranged in parallel, the attenuation effect is enhanced at a single frequency point. When two or more cavities are arranged in series, distributed attenuation is formed at different frequency points.

7. A railway noise control device based on Helmholtz resonance, characterized in that, include: The modeling and verification module is used to build a simulation model of the Helmholtz resonant sound absorber and compare and verify its effectiveness in order to generate a simulation tool that can be used for structural design. The influence analysis module is used to analyze the transmission loss frequency characteristics of different resonant cavity shapes and multiple resonant sound-absorbing unit arrangements based on the simulation tool, so as to obtain the influence law of the shape parameters and arrangement on the transmission loss. The spectrum acquisition and target frequency band determination module is used to acquire the noise frequency characteristics of the target railway line and determine the target noise control frequency band based on the noise frequency characteristics. The structural design module is used to design a Helmholtz resonant sound-absorbing structure using the simulation tool based on the influence law and the target noise control frequency band, and to determine the shape, size and unit arrangement of the resonant cavity that meet the noise reduction requirements of the target frequency band.

8. The apparatus according to claim 7, characterized in that, Also includes: The effect verification module is used to verify the noise reduction effect of the Helmholtz resonant sound absorption device output by the structural design module, and output the noise reduction effect evaluation result of the device in the target noise control frequency band.

9. The apparatus according to claim 7, characterized in that, The structural design module is configured to adjust the aspect ratio of the bottom surface of the square cavity, the diameter-to-height ratio of the cylindrical cavity, or to adopt a spherical cavity structure, while keeping the volume of the resonant cavity constant, in order to adjust the resonant frequency and the peak position of the transmission loss.

10. The apparatus according to claim 7, characterized in that, The railway noise control device is The rail resonant sound absorber is installed on the rail web and / or rail bottom and consists of multiple resonant sound absorbing units of different sizes arranged in parallel. Alternatively, the railway noise control device may be a trackside resonant sound-absorbing barrier, which includes a sound barrier frame and a Helmholtz resonant sound-absorbing panel disposed therein, wherein multiple Helmholtz resonant sound-absorbing units are regularly distributed within the panel.

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