Environment-friendly silencer flow resistance analysis method and system

Abstract

The invention relates to the technical field of silencer flow resistance analysis, in particular to an environment-friendly silencer flow resistance analysis method and system. Performing numerical simulation on the silencing process of the resistive silencer by using fluid dynamics calculation software and acoustic software to determine a noise reduction amount simulation range, a flow velocity difference simulation range, an air pressure difference simulation range and a silencing frequency simulation range; the average inlet sound pressure level and the average outlet sound pressure level of the resistive silencer are obtained to determine the actual noise reduction amount; determining a flow resistance characterization state of the resistive silencer according to the actual noise reduction amount; determining whether flow resistance state diagnosis is carried out or not according to the flow resistance characterization state; according to the environment-friendly silencer flow resistance analysis method provided by the invention, the flow resistance state of a resistive silencer can be comprehensively and accurately evaluated in a mode of combining numerical simulation and actual measurement, the accuracy of silencing effect evaluation is improved, and a reliable basis is provided for optimal design and maintenance of the silencer.

Description

Technical Field

[0001] The present invention relates to the technical field of muffler flow resistance analysis, and in particular to a method and system for analyzing flow resistance of an environmentally friendly muffler. Background Art

[0002] Environmentally friendly muffler is a device that can effectively reduce noise and meet environmental protection requirements. Resistive muffler uses sound-absorbing materials to absorb sound energy. It is filled with porous sound-absorbing materials such as glass wool and rock wool. When sound waves enter the muffler, the sound energy is converted into heat energy by the sound-absorbing materials and consumed. Flow resistance is closely related to muffler performance, and for equipment such as ventilation systems or engine exhaust systems, flow resistance directly affects the operating efficiency of the equipment.

[0003] Patent application publication number CN116467961A discloses a muffler flow resistance analysis method, device, equipment and storage medium. The present invention reduces the hardware requirements for flow resistance calculation by importing the fluid domain model of the muffler into the simulation software, and then determines the simulation function corresponding to the fluid domain model, and initializes the monitoring parameters of the simulation function to facilitate the subsequent flow resistance simulation calculation. Finally, the flow resistance monitoring information of each position obtained by the simulation calculation is exported to generate a flow resistance cloud map of the muffler to facilitate the flow resistance analysis of the muffler, simplifying the steps of flow resistance calculation and reducing hardware costs. The existing technology for calculating the flow resistance of vehicle mufflers has complex steps and high costs, and improves the efficiency of flow resistance calculation and analysis. It can be seen that this method has the following problems:

[0004] This invention only imports the fluid domain model of the muffler into the simulation software to improve the simulation calculation accuracy of the vehicle muffler flow resistance, but does not combine the simulation calculation with the actual test results to quickly and effectively analyze the muffler flow resistance. Summary of the invention

[0005] To this end, the present invention provides an environmentally friendly muffler flow resistance analysis method and system to overcome the problem in the prior art that simulation calculations are not combined with actual test results to quickly and effectively analyze the muffler flow resistance.

[0006] To achieve the above object, on the one hand, the present invention provides a method for analyzing flow resistance of an environmentally friendly muffler, comprising:

[0007] The silencing process of the resistive muffler is numerically simulated using fluid dynamics calculation software and acoustic software to determine the simulation range of noise reduction, velocity difference, air pressure difference, and silencing frequency.

[0008] Obtain the average inlet sound pressure level and average outlet sound pressure level of the resistive muffler to determine the actual noise reduction;

[0009] Determining a flow resistance characterization state of the resistive muffler according to the actual noise reduction amount;

[0010] Determining whether to perform flow resistance state diagnosis according to the flow resistance characterization state includes:

[0011] Outputting the flow resistance characterization status does not perform flow resistance status diagnosis;

[0012] or, performing flow resistance state diagnosis and outputting flow resistance state diagnosis result;

[0013] Wherein, the method for diagnosing the flow resistance state includes:

[0014] Acquire inlet data and outlet data of the resistive muffler, wherein the inlet data includes an inlet flow rate, an inlet air pressure, and an inlet audio spectrum, and the outlet data includes an outlet flow rate, an outlet air pressure, and an outlet audio spectrum;

[0015] Determine the actual flow rate difference according to the absolute value of the difference between the inlet flow rate and the outlet flow rate, and determine the actual air pressure difference according to the absolute value of the difference between the inlet air pressure and the outlet air pressure;

[0016] Determining a flow resistance characterization trend according to the actual flow velocity difference and the actual air pressure difference;

[0017] Determine the actual range of the muffler frequency and the regeneration frequency range according to the inlet audio spectrum diagram and the outlet audio spectrum diagram;

[0018] Determine the anechoic frequency failure range according to the anechoic frequency actual range and the anechoic frequency simulation range;

[0019] The accuracy of the flow resistance characterization trend is determined based on the muffler frequency failure range and the regeneration frequency range to determine a flow resistance state diagnosis result of the resistive muffler.

[0020] Furthermore, the method for determining the actual noise reduction amount includes:

[0021] Obtaining the inlet sound pressure level at each inlet measuring point of the resistive muffler, and determining the average inlet sound pressure level according to the average value of each of the inlet sound pressure levels;

[0022] Obtaining the outlet sound pressure level at each outlet measuring point of the resistive muffler, and determining the average outlet sound pressure level according to the average value of each outlet sound pressure level;

[0023] determining an actual noise reduction amount according to an absolute value of a difference between the average inlet sound pressure level and the average outlet sound pressure level;

[0024] The number of the entry measuring points is equal to the number of the exit measuring points.

[0025] Further, the method for determining the flow resistance characterization state of the resistive muffler according to the actual noise reduction amount includes:

[0026] comparing the actual noise reduction amount with the noise reduction amount simulation range;

[0027] The flow resistance characterization state is determined according to the comparison result, wherein:

[0028] If the actual noise reduction amount exceeds the noise reduction amount simulation range, determining that the flow resistance representation state is a flow resistance abnormal state;

[0029] If the actual noise reduction amount is within the noise reduction amount simulation range, it is determined that the flow resistance representation state is a normal flow resistance state.

[0030] Further, determining whether to perform flow resistance state diagnosis according to the flow resistance characterization state includes:

[0031] If the flow resistance characterization state is a normal flow resistance state, it is determined that no flow resistance state diagnosis is performed and the flow resistance characterization state is output;

[0032] If the flow resistance characterization state is a flow resistance abnormal state, it is determined that a flow resistance state diagnosis is performed and a flow resistance state diagnosis result is output.

[0033] Further, determining the flow resistance characterization trend according to the actual flow velocity difference and the actual air pressure difference includes:

[0034] If the actual flow velocity difference is greater than the flow velocity difference simulation range and the actual air pressure difference is greater than the air pressure difference simulation range, it is determined that the flow resistance characterization trend is an excessive flow resistance trend;

[0035] If the actual flow velocity difference is smaller than the flow velocity difference simulation range and / or the actual air pressure difference is smaller than the air pressure difference simulation range, it is determined that the flow resistance characterization trend is a trend of too small flow resistance.

[0036] Further, the method for determining the actual range of the muffler frequency and the regeneration frequency range according to the inlet audio spectrum diagram and the outlet audio spectrum diagram includes:

[0037] Determine an inlet audio range and an outlet audio range according to the inlet audio spectrum diagram and the outlet audio spectrum diagram respectively;

[0038] Determining the actual range of the muffled frequency according to the relative complement of the outlet audio range in the inlet audio range;

[0039] The reproduction frequency range is determined based on the relative complement of the inlet audio range to the outlet audio range.

[0040] Furthermore, the muffler frequency failure range is determined according to the absolute complement of the muffler frequency actual range within the muffler frequency simulation range.

[0041] Further, the method for determining the flow resistance state diagnosis result of the resistive muffler includes:

[0042] The accuracy of the flow resistance characterization trend is determined based on the muffler frequency failure range and the regeneration frequency range, wherein:

[0043] If both the muffler frequency failure range and the regeneration frequency range belong to high frequencies, the determination that the flow resistance characterization trend is an excessive flow resistance trend is accurate, and the flow resistance state diagnosis result of the resistive muffler is determined to be an excessive flow resistance;

[0044] If the muffler frequency failure range and the regeneration frequency range are both low frequencies, the determination that the flow resistance characterization trend is too small flow resistance is accurate, and the flow resistance state diagnosis result of the resistive muffler is determined to be too small flow resistance.

[0045] On the other hand, the present invention also provides an environmental protection muffler flow resistance analysis system, comprising:

[0046] Numerical simulation module, used to perform numerical simulation on the muffler process of the resistive muffler using fluid dynamics calculation software and acoustic software to determine the simulation range of noise reduction, flow velocity difference, air pressure difference, and muffler frequency;

[0047] A data acquisition module, used to obtain the inlet sound pressure level at each inlet measuring point of the resistive muffler, the outlet sound pressure level at each outlet measuring point, the inlet flow rate, the inlet air pressure, the outlet flow rate, the outlet air pressure, the inlet audio data and the outlet audio data; a data processing module, which is connected to the data acquisition module, and is used to determine the average inlet sound pressure level according to the inlet sound pressure level at each inlet measuring point, determine the average outlet sound pressure level according to the outlet sound pressure level at each outlet measuring point, and determine the inlet audio spectrum and the outlet audio spectrum according to the inlet audio data and the outlet audio data respectively;

[0048] a flow resistance analysis module, which is connected to the numerical simulation module and the data processing module respectively, and is used to determine the flow resistance characterization state of the resistive muffler according to the actual noise reduction amount to determine whether to perform flow resistance state diagnosis, determine the actual flow velocity difference according to the absolute value of the difference between the inlet flow velocity and the outlet flow velocity, determine the actual air pressure difference according to the absolute value of the difference between the inlet air pressure and the outlet air pressure, determine the flow resistance characterization trend according to the actual flow velocity difference and the actual air pressure difference, determine the actual range of silencer frequency and the regeneration frequency range according to the inlet audio spectrum diagram and the outlet audio spectrum diagram, determine the silencer frequency failure range according to the actual range of silencer frequency and the silencer frequency simulation range, and determine the accuracy of the flow resistance characterization trend according to the silencer frequency failure range and the regeneration frequency range to determine the flow resistance state diagnosis result of the resistive muffler.

[0049] Furthermore, the data acquisition module includes:

[0050] A sound pressure level acquisition unit, including a plurality of sound level meters, for obtaining the inlet sound pressure level at each inlet measuring point of the resistive muffler and the outlet sound pressure level at each outlet measuring point;

[0051] A flow rate sensor unit for obtaining an inlet flow rate and an outlet flow rate of a resistive sensor;

[0052] An air pressure sensor unit for obtaining the inlet and outlet air pressures of the resistive muffler;

[0053] The audio sensor unit is used to obtain the inlet audio data and the outlet audio data of the resistive muffler.

[0054] Compared with the prior art, the beneficial effect of the present invention is that the environmental protection muffler flow resistance analysis method provided by the present invention can comprehensively and accurately evaluate the flow resistance state of the resistive muffler by combining numerical simulation with actual measurement, improve the accuracy of the muffler effect evaluation, and provide a reliable basis for the optimization design and maintenance of the muffler;

[0055] Furthermore, the present invention uses fluid dynamics calculation software and acoustic software to perform numerical simulations to determine the simulation range of noise reduction, flow velocity difference, air pressure difference and silencing frequency, providing a theoretical reference for subsequent actual measurements; and by comparing the actual measurement values ​​with the simulation values, the performance of the muffler can be evaluated more accurately and the error can be reduced;

[0056] Furthermore, the present invention determines the flow resistance characterization state by obtaining the inlet and outlet sound pressure levels of the resistive muffler to determine the actual noise reduction amount, determines whether the flow resistance is appropriate according to the flow resistance characterization state, and preliminarily determines the flow resistance characterization trend (flow rate is too large / too small) by considering the flow velocity difference and the air pressure difference when it is not appropriate, and comprehensively determines the accuracy of the flow resistance characterization trend according to the actual range of the muffler frequency and the regeneration frequency range, thereby being able to comprehensively, systematically and accurately evaluate the flow resistance state of the muffler;

[0057] Furthermore, the present invention can timely discover problems existing in the muffler based on the flow resistance state diagnosis results, and can provide a clear direction for the optimal design and maintenance of the muffler, which is helpful to improve the muffler effect and extend the service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 A step diagram of a method for analyzing flow resistance of an environmentally friendly muffler according to an embodiment of the present invention;

[0059] Figure 2 This is a flow chart of environmental protection flow resistance state diagnosis according to an embodiment of the present invention;

[0060] Figure 3 A diagram showing the steps of determining the actual range of the muffler frequency and the regeneration frequency range according to an embodiment of the present invention;

[0061] Figure 4 It is a connection diagram of the environmental protection muffler flow resistance analysis system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0062] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0063] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0064] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0065] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0066] See also Figure 1 and Figure 2 As shown, they are respectively a step diagram of an environmental muffler flow resistance analysis method according to an embodiment of the present invention and a flow chart of an environmental flow resistance state diagnosis according to an embodiment of the present invention. The present invention provides an environmental muffler flow resistance analysis method, comprising:

[0067] Step S1, using fluid dynamics calculation software and acoustic software to perform numerical simulation on the muffler process of the resistive muffler to determine the noise reduction amount simulation range, flow velocity difference simulation range, air pressure difference simulation range, and muffler frequency simulation range; in implementation, the same parameters as the actual detection process are input into the fluid dynamics calculation software and the acoustic software for simulation to obtain the corresponding noise reduction amount simulation range (this range belongs to the range that can be heard by humans), flow velocity difference simulation range, air pressure difference simulation range, and muffler frequency simulation range;

[0068] Step S2, obtaining the average inlet sound pressure level and the average outlet sound pressure level of the resistive muffler to determine the actual noise reduction amount;

[0069] Step S3, determining the flow resistance characterization state of the resistive muffler according to the actual noise reduction amount;

[0070] Step S4, determining whether to perform flow resistance state diagnosis according to the flow resistance characterization state, including:

[0071] Outputting the flow resistance characterization status does not perform flow resistance status diagnosis;

[0072] or, performing flow resistance state diagnosis and outputting flow resistance state diagnosis result;

[0073] Wherein, the method for diagnosing the flow resistance state includes:

[0074] Acquire inlet data and outlet data of the resistive muffler, wherein the inlet data includes an inlet flow rate, an inlet air pressure, and an inlet audio spectrum, and the outlet data includes an outlet flow rate, an outlet air pressure, and an outlet audio spectrum;

[0075] Determine the actual flow rate difference according to the absolute value of the difference between the inlet flow rate and the outlet flow rate, and determine the actual air pressure difference according to the absolute value of the difference between the inlet air pressure and the outlet air pressure;

[0076] Determining a flow resistance characterization trend according to the actual flow velocity difference and the actual air pressure difference;

[0077] Determine the actual range of the muffler frequency and the regeneration frequency range according to the inlet audio spectrum diagram and the outlet audio spectrum diagram;

[0078] Determine the anechoic frequency failure range according to the anechoic frequency actual range and the anechoic frequency simulation range;

[0079] The accuracy of the flow resistance characterization trend is determined based on the muffler frequency failure range and the regeneration frequency range to determine a flow resistance state diagnosis result of the resistive muffler.

[0080] It can be understood that the environmentally friendly silencer flow resistance analysis method provided by the present invention can comprehensively and accurately evaluate the flow resistance state of the resistive silencer through a combination of numerical simulation and actual measurement, improve the accuracy of the silencer effect evaluation, and provide a reliable basis for the optimal design and maintenance of the silencer. (1) First, numerical simulation is performed using fluid dynamics calculation software and acoustic software to determine the simulation range of noise reduction, flow velocity difference, air pressure difference and silencing frequency, which provides a theoretical reference for subsequent actual measurements; then, by comparing the actual measured values ​​with the simulated values, the performance of the muffler can be evaluated more accurately and the error can be reduced; (2) The actual noise reduction is determined by obtaining the inlet and outlet sound pressure levels of the resistive muffler to determine the flow resistance characterization state, and whether the flow resistance size is appropriate is determined based on the flow resistance characterization state. If it is not appropriate, the flow velocity difference and air pressure difference are considered to preliminarily determine the flow resistance characterization trend (flow velocity is too large / too small), and the accuracy of the flow resistance characterization trend is comprehensively determined based on the actual silencing frequency range and the regeneration frequency range, so that the flow resistance state of the muffler can be comprehensively, systematically and accurately evaluated; (3) According to the flow resistance state diagnosis results, the problems existing in the muffler can be discovered in time, which can provide a clear direction for the optimization design and maintenance of the muffler, help improve the silencing effect, and extend the service life of the equipment; (4) By accurately evaluating and optimizing the flow resistance state of the muffler, noise pollution can be reduced and environmental quality can be improved.

[0081] It can be understood that the noise reduction amount is a physical quantity that measures the degree to which noise is reduced by noise reduction measures (such as the use of silencers, sound insulation materials, etc.), and reflects the difference in noise intensity before and after the measures are taken; that is, the degree to which the sound energy of the noise source is attenuated after noise reduction treatment under specific environments and conditions, and the unit is usually decibel (dB).

[0082] Specifically, in step S2, the method for determining the actual noise reduction amount includes:

[0083] Step S21, obtaining the inlet sound pressure level at each inlet measuring point of the resistive muffler, and determining the average inlet sound pressure level according to the average value of each inlet sound pressure level;

[0084] Step S22, obtaining the outlet sound pressure level at each outlet measuring point of the resistive muffler, and determining the average outlet sound pressure level according to the average value of each outlet sound pressure level;

[0085] Step S23, determining an actual noise reduction amount according to an absolute value of a difference between the average inlet sound pressure level and the average outlet sound pressure level;

[0086] The number of the entry measuring points is equal to the number of the exit measuring points.

[0087] It can be understood that when measuring the average sound pressure level difference, first, each sound level meter is placed at a suitable position of the muffler inlet cross section (at each inlet measuring point). For a stable noise source, multiple measuring points can be selected on the cross section (for example, on a circular pipe cross section, multiple points are selected at a certain angle interval and radius position); then the microphone of the sound level meter is aimed at each measuring point in turn, and the sound pressure level of each measuring point is recorded; after the measurement is completed, the sound level meter uses the built-in statistical function or transfers the data to the computer software for averaging calculation to obtain the average sound pressure level of the inlet cross section (average inlet sound pressure level), and then the sound level meter is placed at a suitable position of the muffler outlet (at each outlet measuring point) to perform the same measurement operation to obtain the average outlet sound pressure level; finally, the actual noise reduction amount is calculated based on the difference between the two average sound pressure levels.

[0088] In practice, the methods for arranging measuring points include: (1) circular inlet: if the muffler inlet is circular, the equal-area circular ring method or the equal-angle ray method is usually used to arrange the measuring points; for the equal-area circular ring method, the inlet cross section is divided into several concentric circular rings, and the measuring points are evenly arranged on each circular ring. In one implementation, 3 to 5 circular rings can be divided, and 4 to 8 measuring points are arranged on each circular ring; for the equal-angle ray method, a number of rays are radiated outward from the center of the circle, and the measuring points are arranged at equal distances on each ray. The number of rays is generally not less than 6; (2) square or rectangular inlet: for square or rectangular inlet, the grid method can be used to arrange the measuring points; the inlet cross section is divided into several equal small rectangular or square grids, and the measuring points are arranged at the center of each grid. The size of the grid is determined according to the inlet size and the measurement accuracy requirements. Generally, the side length of the grid is less than one-third of the side length of the inlet.

[0089] In practice, the measurement process includes: firstly, placing the sound level meter at each measuring point to ensure that the microphone is pointed in the correct direction (towards the direction of the sound source); turning on the sound level meter and recording the sound pressure level readings at each measuring point.

[0090] In practice, only one sound level meter may be used to determine the sound pressure level at each measuring point one by one.

[0091] Specifically, the method for determining the flow resistance characterization state of the resistive muffler according to the actual noise reduction amount includes:

[0092] Step S31, comparing the actual noise reduction amount with the noise reduction amount simulation range; it can be understood that in implementation, the noise reduction amount is used to represent the noise reduction amount of the resistive muffler;

[0093] Step S32, determining the flow resistance characterization state according to the comparison result, wherein:

[0094] If the actual noise reduction amount exceeds the noise reduction amount simulation range (in implementation, the actual noise reduction amount is less than the noise reduction amount simulation range), the flow resistance characterization state is determined to be a flow resistance abnormal state;

[0095] If the actual noise reduction amount is within the noise reduction amount simulation range, it is determined that the flow resistance representation state is a normal flow resistance state.

[0096] It can be understood that the flow resistance is closely related to the sound attenuation. When the flow resistance is moderate, the sound waves can be better propagated and absorbed in the sound-absorbing material inside the muffler, which is beneficial to improve the sound attenuation. In one implementation, at a certain air flow speed, appropriate flow resistance can make the sound waves pass through the area filled with the sound-absorbing material evenly, so that the sound-absorbing material can give full play to its sound absorption effect. However, if the flow resistance is too large, it will cause the airflow to form an uneven flow inside the muffler. In one implementation, high-speed airflow channels may be generated in certain local areas of the sound-absorbing material, so that the sound waves cannot fully contact the sound-absorbing material, thereby reducing the sound absorption effect and reducing the sound attenuation. On the contrary, too small a flow resistance may mean that the filling density of the sound-absorbing material is insufficient or the muffler structure is too simple to effectively attenuate the sound waves, which will also lead to insufficient sound attenuation.

[0097] Specifically, determining whether to perform flow resistance state diagnosis according to the flow resistance characterization state includes:

[0098] If the flow resistance characterization state is a normal flow resistance state, it is determined that no flow resistance state diagnosis is performed and the flow resistance characterization state is output;

[0099] If the flow resistance characterization state is an abnormal flow resistance state, the flow resistance state diagnosis is performed and the flow resistance state diagnosis result is output; it can be understood that if the actual noise reduction amount is less than the noise reduction amount simulation range, the flow resistance characterization state is judged to be abnormal. At this time, it is impossible to determine whether the flow resistance is too large or too small, so the flow resistance state diagnosis is required.

[0100] It can be understood that by comparing the actual noise reduction amount with the noise reduction simulation range to determine the flow resistance characterization state of the resistive muffler, it is possible to identify whether the flow resistance of the muffler is normal, and based on this, decide whether to conduct in-depth flow resistance state diagnosis, thereby timely discovering and solving muffler performance problems, improving noise control efficiency, optimizing equipment maintenance strategies, and ensuring long-term and stable operation of the muffler.

[0101] Specifically, determining the flow resistance characterization trend according to the actual flow velocity difference and the actual air pressure difference includes:

[0102] If the actual flow velocity difference is greater than the flow velocity difference simulation range and the actual air pressure difference is greater than the air pressure difference simulation range, then the flow resistance characterization trend is determined to be an excessive flow resistance trend; it is understandable that the air flow velocity will be greatly reduced in the area with larger flow resistance inside the muffler, so the flow velocity difference should be larger; larger flow resistance will bring about larger pressure loss; therefore, when the actual flow velocity difference is greater than the flow velocity difference simulation range and the actual air pressure difference is greater than the air pressure difference simulation range, it can be determined that the flow resistance characterization trend is an excessive flow resistance trend; and at this time, the judgment on the flow resistance characterization trend is highly likely to be accurate, and it is generally believed that the judgment is accurate; therefore, in implementation, its accuracy can be determined based on the muffler frequency failure range and the regeneration frequency range, or its accuracy can be no longer judged;

[0103] If the actual flow velocity difference is smaller than the flow velocity difference simulation range and / or the actual air pressure difference is smaller than the air pressure difference simulation range, the flow resistance characterization trend is determined to be a trend of too small flow resistance; it is understandable that inside the muffler, the air flow velocity in the channel with smaller local flow resistance may decrease or speed up slightly, so the flow velocity difference should be smaller; smaller flow resistance will bring smaller pressure loss; therefore, when the actual flow velocity difference is smaller than the flow velocity difference simulation range and / or the actual air pressure difference is smaller than the air pressure difference simulation range, the flow resistance characterization trend is determined to be a trend of too small flow resistance, and the accuracy of the flow resistance characterization trend needs to be determined based on the muffler frequency failure range and the regeneration frequency range.

[0104] It is understandable that flow resistance will change the air flow velocity distribution inside the muffler and at the inlet and outlet: when the air flow enters a muffler with a certain flow resistance, the air flow velocity will change due to the effect of resistance.

[0105] It is understandable that flow resistance also directly leads to pressure loss: when the airflow passes through a resistive muffler, the flow resistance will cause a pressure difference between the inlet and outlet of the muffler; a larger flow resistance will cause a larger pressure loss, which means that the power equipment such as the fan or engine needs to consume more energy to overcome this pressure difference and push the airflow through the muffler.

[0106] It can be understood that by comprehensively considering the actual flow velocity difference and the actual air pressure difference, the flow resistance characterization trend of the resistive muffler can be quickly preliminarily judged, which provides a scientific basis for the performance evaluation, fault diagnosis and optimization of the muffler.

[0107] It can be understood that the horizontal axis of the audio spectrum diagram is frequency, and the unit is generally Hertz (Hz); the vertical axis is amplitude, and the common unit is decibel (dB); through the spectrum diagram, the energy distribution of the signal at different frequencies can be analyzed.

[0108] See also Figure 3 As shown, it is a step diagram of determining the actual range of the muffler frequency and the regeneration frequency range according to an embodiment of the present invention. Specifically, the method for determining the actual range of the muffler frequency and the regeneration frequency range according to the inlet audio spectrum diagram and the outlet audio spectrum diagram includes:

[0109] Determine an inlet audio range and an outlet audio range according to the inlet audio spectrum diagram and the outlet audio spectrum diagram respectively;

[0110] The actual range of the muffler frequency is determined according to the relative complement of the outlet audio range in the inlet audio range; in one implementation, the inlet audio range is A and its corresponding interval is a1-a2, the inlet audio range is B and its corresponding interval is b1-b2, the relative complement of the outlet audio range in the inlet audio range is the part belonging to the a1-a2 interval but not belonging to the b1-b2 interval, which is recorded as c1-c2, and the c1-c2 interval is the actual range of the muffler frequency;

[0111] The regeneration frequency range is determined according to the relative complement of the inlet audio range in the outlet audio range; in one implementation, the inlet audio range is A and its corresponding interval is a1~a2, the inlet audio range is B and its corresponding interval is b1~b2, the relative complement of the outlet audio range in the inlet audio range is the part belonging to the b1~b2 interval but not belonging to the a1~a2 interval, which is denoted as d1~d2, and the interval d1~d2 is the regeneration frequency range.

[0112] Specifically, the muffler frequency failure range is determined according to the absolute complement of the muffler frequency actual range in the muffler frequency simulation range.

[0113] In implementation, the actual range of the anechoic frequency should be a subset of the anechoic frequency simulation range (because the simulations are all calculated according to ideal conditions and should perform better than the actual results, that is, the anechoic frequency range should be larger). The absolute complement of the actual range of the anechoic frequency in the anechoic frequency simulation range is the anechoic frequency failure range.

[0114] It can be understood that by comparing the inlet audio spectrum with the outlet audio spectrum, the actual range of the muffler frequency and the regeneration frequency range can be accurately determined, and the failure range of the muffler frequency can be further analyzed, which provides strong data support for the performance evaluation and optimization of the muffler; this method helps to improve the accuracy of the muffler performance evaluation. (1) By comparing the inlet and outlet audio spectrum, it is possible to accurately identify the frequency ranges in which the muffler achieves effective noise elimination (actual range of the muffler frequency) and the frequency ranges in which noise regeneration or enhancement occurs (regeneration frequency range). This precise determination of the frequency range helps to gain a deeper understanding of the performance characteristics of the muffler and provide a basis for subsequent optimization design; (2) After determining the actual muffler frequency range, it is compared with the muffler frequency simulation range to identify the muffler frequency failure range, which helps to find the frequency region where the muffler fails to achieve the expected muffler effect in actual application, providing key clues for subsequent troubleshooting and performance optimization; (3) By obtaining the actual muffler frequency range, regeneration frequency range and muffler frequency failure range, more comprehensive and accurate data support is provided for the performance evaluation of the muffler. Compared with traditional evaluation methods, this method can more accurately reflect the actual performance of the muffler and help improve the accuracy and credibility of the evaluation results.

[0115] Specifically, the method for determining the flow resistance state diagnosis result of the resistive muffler includes:

[0116] The accuracy of the flow resistance characterization trend is determined based on the muffler frequency failure range and the regeneration frequency range, wherein:

[0117] If both the muffler frequency failure range and the regeneration frequency range belong to high frequencies, the determination that the flow resistance characterization trend is an excessive flow resistance trend is accurate, and the flow resistance state diagnosis result of the resistive muffler is determined to be an excessive flow resistance;

[0118] If the muffler frequency failure range and the regeneration frequency range are both low frequencies, the determination that the flow resistance characterization trend is too small flow resistance is accurate, and the flow resistance state diagnosis result of the resistive muffler is determined to be too small flow resistance.

[0119] It is understandable that the effective sound-absorbing frequency range of the muffler will also change under different flow resistances: usually moderate flow resistance helps to broaden the effective sound-absorbing frequency bandwidth of the muffler, and the muffler effect of resistive mufflers on medium and high frequency noise is usually better, that is, when the flow resistance is appropriate, the medium and high frequency sound waves can be better absorbed in the sound-absorbing material, and at the same time, the low frequency sound waves can be attenuated to a certain extent through appropriate reflection and interference. However, if the flow resistance is too large, the high frequency sound waves may be reflected and scattered inside the muffler, and cannot effectively enter the sound-absorbing material, thereby reducing the effective range of high frequency sound absorption; if the flow resistance is too small, the attenuation ability of low frequency sound waves may be weak, so that low frequency noise cannot be effectively processed in the muffler, and the effective sound absorption frequency range of the muffler will also be limited.

[0120] It is understandable that the size of the flow resistance will directly affect the frequency characteristics of the airflow regeneration noise: a larger flow resistance will often lead to an increase in high-frequency regeneration noise components. This is because under high flow resistance, the turbulence and eddy currents of the airflow are more likely to produce high-frequency vibrations on small-scale structures (such as pores in sound-absorbing materials, thin-walled structures, etc.). Therefore, when the flow resistance is too large, the flow of the airflow inside the muffler will be more turbulent, and turbulence and eddy currents will easily occur. These unstable airflows will excite the components inside the muffler (such as pipe walls, partitions, and sound-absorbing materials, etc.) to vibrate, thereby generating strong airflow regeneration noise. At this time, measures such as increasing high-frequency sound-absorbing materials can be used to reduce the high-frequency regeneration noise. On the contrary, when the flow resistance is small, the regeneration noise intensity generated by the relatively stable airflow is relatively low, and the regeneration noise may be dominated by low-frequency components. This is because the relatively stable airflow mainly causes low-frequency vibrations of larger structural components (such as muffler housings, large-area partitions, etc.). At this time, the resistive muffler should be repaired to tighten the various structures of the muffler.

[0121] In practice, when the flow resistance is too large, the anechoic frequency failure range and the regeneration frequency range should both be high frequency, and when the flow resistance is too small, the anechoic frequency failure range and the regeneration frequency range should both be low frequency. Therefore, by comprehensively considering the consistency of the anechoic frequency failure range and the regeneration frequency range, the accuracy of the flow resistance characterization trend can be accurately determined.

[0122] It can be understood that by comprehensively considering the consistency of the silencing frequency failure range and the regeneration frequency range, the flow resistance characterization trend of the resistive muffler can be accurately judged, which provides a scientific basis for the performance evaluation, fault diagnosis and optimization of the muffler; (1) By comparing the silencing frequency failure range and the regeneration frequency range, it is possible to accurately judge whether the flow resistance of the resistive muffler is too large or too small. This judgment method is not only direct and effective, but also avoids the misjudgment caused by single parameter judgment in traditional methods, thereby improving the accuracy and reliability of the judgment; (2) Accurate judgment of the flow resistance state can provide a scientific basis for the performance evaluation of the muffler: for example, when evaluating the noise reduction effect of the muffler, the flow resistance state can be comprehensively considered to more accurately judge whether the performance of the muffler meets the requirements; in addition, it can also provide strong support for the fault diagnosis of the muffler, help quickly locate the cause of the fault, and improve maintenance efficiency; (3) Based on this information, designers can adjust the structural parameters of the muffler, the selection and layout of sound-absorbing materials, etc. in a targeted manner to improve its muffler effect within a specific frequency range and enhance overall performance.

[0123] See also Figure 4 As shown, it is a connection diagram of the environmental protection muffler flow resistance analysis system of the embodiment of the present invention. The present invention also provides an environmental protection muffler flow resistance analysis system, including:

[0124] Numerical simulation module, used to perform numerical simulation on the muffler process of the resistive muffler using fluid dynamics calculation software and acoustic software to determine the simulation range of noise reduction, flow velocity difference, air pressure difference, and muffler frequency;

[0125] A data acquisition module is used to obtain the inlet sound pressure level at each inlet measuring point of the resistive muffler, the outlet sound pressure level at each outlet measuring point, the inlet flow rate, the inlet air pressure, the outlet flow rate, the outlet air pressure, the inlet audio data and the outlet audio data;

[0126] a data processing module connected to the data acquisition module, for determining an average inlet sound pressure level according to the inlet sound pressure level at each of the inlet measuring points, determining an average outlet sound pressure level according to the outlet sound pressure level at each of the outlet measuring points, and determining an inlet audio spectrogram and an outlet audio spectrogram according to the inlet audio data and the outlet audio data, respectively;

[0127] a flow resistance analysis module, which is connected to the numerical simulation module and the data processing module respectively, and is used to determine the flow resistance characterization state of the resistive muffler according to the actual noise reduction amount to determine whether to perform flow resistance state diagnosis, determine the actual flow velocity difference according to the absolute value of the difference between the inlet flow velocity and the outlet flow velocity, determine the actual air pressure difference according to the absolute value of the difference between the inlet air pressure and the outlet air pressure, determine the flow resistance characterization trend according to the actual flow velocity difference and the actual air pressure difference, determine the actual range of silencer frequency and the regeneration frequency range according to the inlet audio spectrum diagram and the outlet audio spectrum diagram, determine the silencer frequency failure range according to the actual range of silencer frequency and the silencer frequency simulation range, and determine the accuracy of the flow resistance characterization trend according to the silencer frequency failure range and the regeneration frequency range to determine the flow resistance state diagnosis result of the resistive muffler.

[0128] Specifically, the data acquisition module includes:

[0129] A sound pressure level acquisition unit, including a plurality of sound level meters, for obtaining the inlet sound pressure level at each inlet measuring point of the resistive muffler and the outlet sound pressure level at each outlet measuring point;

[0130] It can be understood that a sound level meter is a commonly used acoustic measuring instrument that can convert sound signals into electrical signals, and then process and analyze the electrical signals through internal circuits: its core components include microphones, amplifiers, filters and display units, etc. The microphone is used to receive sound signals and convert them into electrical signals, the amplifier amplifies the electrical signals, the filter can select different frequency ranges for measurement as needed, and finally the measurement results are output through the display unit, including information such as sound pressure level.

[0131] A flow rate sensor unit for obtaining an inlet flow rate and an outlet flow rate of a resistive sensor;

[0132] An air pressure sensor unit for obtaining the inlet and outlet air pressures of the resistive muffler;

[0133] The audio sensor unit is used to obtain the inlet audio data and the outlet audio data of the resistive muffler.

[0134] It is understandable that the flow rate sensor, the air pressure sensor and the audio sensor are any one of the existing sensors, so they will not be described in detail.

[0135] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0136] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for analyzing flow resistance of an environmentally friendly muffler, characterized in that: include: The silencing process of the resistive muffler is numerically simulated using fluid dynamics calculation software and acoustic software to determine the simulation range of noise reduction, velocity difference, air pressure difference, and silencing frequency. Obtain the average inlet sound pressure level and average outlet sound pressure level of the resistive muffler to determine the actual noise reduction; Determining a flow resistance characterization state of the resistive muffler according to the actual noise reduction amount; Determining whether to perform flow resistance state diagnosis according to the flow resistance characterization state includes: Outputting the flow resistance characterization status does not perform flow resistance status diagnosis; or, performing flow resistance state diagnosis and outputting flow resistance state diagnosis result; Wherein, the method for diagnosing the flow resistance state includes: Acquire inlet data and outlet data of the resistive muffler, wherein the inlet data includes an inlet flow rate, an inlet air pressure, and an inlet audio spectrum, and the outlet data includes an outlet flow rate, an outlet air pressure, and an outlet audio spectrum; Determine the actual flow rate difference according to the absolute value of the difference between the inlet flow rate and the outlet flow rate, and determine the actual air pressure difference according to the absolute value of the difference between the inlet air pressure and the outlet air pressure; Determining a flow resistance characterization trend according to the actual flow velocity difference and the actual air pressure difference; Determine the actual range of the muffler frequency and the regeneration frequency range according to the inlet audio spectrum diagram and the outlet audio spectrum diagram; Determine the anechoic frequency failure range according to the anechoic frequency actual range and the anechoic frequency simulation range; The accuracy of the flow resistance characterization trend is determined based on the muffler frequency failure range and the regeneration frequency range to determine a flow resistance state diagnosis result of the resistive muffler.

2. The environmental protection muffler flow resistance analysis method according to claim 1 is characterized in that: The method for determining the actual noise reduction amount includes: Obtaining the inlet sound pressure level at each inlet measuring point of the resistive muffler, and determining the average inlet sound pressure level according to the average value of each of the inlet sound pressure levels; Obtaining the outlet sound pressure level at each outlet measuring point of the resistive muffler, and determining the average outlet sound pressure level according to the average value of each outlet sound pressure level; determining an actual noise reduction amount according to an absolute value of a difference between the average inlet sound pressure level and the average outlet sound pressure level; The number of the entry measuring points is equal to the number of the exit measuring points.

3. The environmental protection muffler flow resistance analysis method according to claim 1 is characterized in that: The method for determining the flow resistance characterization state of the resistive muffler according to the actual noise reduction amount includes: comparing the actual noise reduction amount with the noise reduction amount simulation range; The flow resistance characterization state is determined according to the comparison result, wherein: If the actual noise reduction amount exceeds the noise reduction amount simulation range, determining that the flow resistance representation state is a flow resistance abnormal state; If the actual noise reduction amount is within the noise reduction amount simulation range, it is determined that the flow resistance representation state is a normal flow resistance state.

4. The environmental protection muffler flow resistance analysis method according to claim 1 is characterized in that: Determining whether to perform flow resistance state diagnosis according to the flow resistance characterization state includes: If the flow resistance characterization state is a normal flow resistance state, it is determined that no flow resistance state diagnosis is performed and the flow resistance characterization state is output; If the flow resistance characterization state is a flow resistance abnormal state, it is determined that a flow resistance state diagnosis is performed and a flow resistance state diagnosis result is output.

5. The environmental protection muffler flow resistance analysis method according to claim 4 is characterized in that: Determining a flow resistance characterization trend according to the actual flow velocity difference and the actual air pressure difference includes: If the actual flow velocity difference is greater than the flow velocity difference simulation range and the actual air pressure difference is greater than the air pressure difference simulation range, it is determined that the flow resistance characterization trend is an excessive flow resistance trend; If the actual flow velocity difference is smaller than the flow velocity difference simulation range and / or the actual air pressure difference is smaller than the air pressure difference simulation range, it is determined that the flow resistance characterization trend is a trend of too small flow resistance.

6. The environmental protection muffler flow resistance analysis method according to claim 1 is characterized in that: The method for determining the actual range of the muffler frequency and the regeneration frequency range according to the inlet audio spectrum diagram and the outlet audio spectrum diagram comprises: Determine an inlet audio range and an outlet audio range according to the inlet audio spectrum diagram and the outlet audio spectrum diagram respectively; Determining the actual range of the muffled frequency according to the relative complement of the outlet audio range in the inlet audio range; The reproduction frequency range is determined based on the relative complement of the inlet audio range to the outlet audio range.

7. The environmental protection muffler flow resistance analysis method according to claim 1 is characterized in that: The muffler frequency failure range is determined according to the absolute complement of the muffler frequency actual range within the muffler frequency simulation range.

8. The environmental protection muffler flow resistance analysis method according to claim 1 is characterized in that: Methods for determining the flow resistance state diagnostic results of a resistive muffler include, The accuracy of the flow resistance characterization trend is determined based on the muffler frequency failure range and the regeneration frequency range, wherein: If both the muffler frequency failure range and the regeneration frequency range belong to high frequencies, the determination that the flow resistance characterization trend is an excessive flow resistance trend is accurate, and the flow resistance state diagnosis result of the resistive muffler is determined to be an excessive flow resistance; If the muffler frequency failure range and the regeneration frequency range are both low frequencies, the determination that the flow resistance characterization trend is too small flow resistance is accurate, and the flow resistance state diagnosis result of the resistive muffler is determined to be too small flow resistance.

9. An environmental muffler flow resistance analysis system using the environmental muffler flow resistance analysis method according to any one of claims 1 to 8, characterized in that: Numerical simulation module, used to perform numerical simulation on the muffler process of the resistive muffler using fluid dynamics calculation software and acoustic software to determine the simulation range of noise reduction, flow velocity difference, air pressure difference, and muffler frequency; A data acquisition module is used to obtain the inlet sound pressure level at each inlet measuring point of the resistive muffler, the outlet sound pressure level at each outlet measuring point, the inlet flow rate, the inlet air pressure, the outlet flow rate, the outlet air pressure, the inlet audio data and the outlet audio data; a data processing module connected to the data acquisition module, for determining an average inlet sound pressure level according to the inlet sound pressure level at each of the inlet measuring points, determining an average outlet sound pressure level according to the outlet sound pressure level at each of the outlet measuring points, and determining an inlet audio spectrogram and an outlet audio spectrogram according to the inlet audio data and the outlet audio data, respectively; a flow resistance analysis module, which is respectively connected to the numerical simulation module and the data processing module, and is used to determine the flow resistance characterization state of the resistive muffler according to the actual noise reduction amount to determine whether to perform flow resistance state diagnosis, determine the actual flow velocity difference according to the absolute value of the difference between the inlet flow velocity and the outlet flow velocity, determine the actual air pressure difference according to the absolute value of the difference between the inlet air pressure and the outlet air pressure, determine the flow resistance characterization trend according to the actual flow velocity difference and the actual air pressure difference, determine the actual range of the muffler frequency and the regeneration frequency range according to the inlet audio spectrum diagram and the outlet audio spectrum diagram, determine the muffler frequency failure range according to the actual range of the muffler frequency and the muffler frequency simulation range, and determine the accuracy of the flow resistance characterization trend according to the muffler frequency failure range and the regeneration frequency range to determine the flow resistance state diagnosis result of the resistive muffler.

10. The environmentally friendly muffler flow resistance analysis system according to claim 9, characterized in that: The data acquisition module includes: A sound pressure level acquisition unit, including a plurality of sound level meters, for obtaining the inlet sound pressure level at each inlet measuring point of the resistive muffler and the outlet sound pressure level at each outlet measuring point; A flow rate sensor unit for obtaining an inlet flow rate and an outlet flow rate of a resistive sensor; An air pressure sensor unit for obtaining the inlet and outlet air pressures of the resistive muffler; The audio sensor unit is used to obtain the inlet audio data and the outlet audio data of the resistive muffler.

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