An environmentally friendly muffler flow resistance analysis method and system

Abstract

The present application relates to the technical field of muffler flow resistance analysis, and particularly relates to an environmental protection muffler flow resistance analysis method and system, which uses fluid dynamics calculation software and acoustic software to perform numerical simulation on the muffling process of a resistive muffler to determine a noise reduction amount simulation range, a flow velocity difference simulation range, a gas pressure difference simulation range and a muffling frequency simulation range; average inlet sound pressure level and average outlet sound pressure level of the resistive muffler are obtained to determine an actual noise reduction amount; a flow resistance characterization state of the resistive muffler is determined according to the actual noise reduction amount; whether to perform flow resistance state diagnosis is determined according to the flow resistance characterization state; the environmental protection muffler flow resistance analysis method provided by the present application 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 evaluation of the muffling effect, and provide a reliable basis for the optimized design and maintenance of the muffler.

Description

Technical Field

[0001] This invention relates to the field of flow resistance analysis technology for mufflers, and in particular to a method and system for flow resistance analysis of environmentally friendly mufflers. Background Technology

[0002] An environmentally friendly silencer is a device that effectively reduces noise while meeting environmental protection requirements. A resistive silencer utilizes sound-absorbing materials to absorb sound energy. Its interior is filled with porous sound-absorbing materials such as glass wool or rock wool. When sound waves enter the silencer, the sound energy is converted into heat energy and dissipated by the sound-absorbing material. Flow resistance is closely related to noise reduction 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 method, apparatus, device, and storage medium for muffler flow resistance analysis. This invention reduces the hardware requirements for flow resistance calculation by importing the muffler's fluid domain model into simulation software. It then determines the simulation function corresponding to the fluid domain model and initializes the monitoring parameters of the simulation function to facilitate subsequent flow resistance simulation calculations. Finally, it exports the flow resistance monitoring information obtained from the simulation calculations at various locations to generate a flow resistance cloud map of the muffler, facilitating flow resistance analysis. This simplifies the flow resistance calculation steps and reduces hardware costs. Existing technologies for calculating vehicle muffler flow resistance suffer from complex steps and high costs, thus improving the efficiency of flow resistance calculation and analysis. However, 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 flow resistance of the vehicle muffler, but does not combine the simulation calculation with the actual test results to quickly and effectively analyze the flow resistance of the muffler. Summary of the Invention

[0005] Therefore, the present invention provides a method and system for analyzing the flow resistance of environmentally friendly mufflers, which overcomes the problem in the prior art that the simulation calculations and actual test results are not combined to quickly and effectively analyze the flow resistance of mufflers.

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

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

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

[0009] The flow resistance characterization state of the resistive muffler is determined based on the actual noise reduction amount.

[0010] Determining whether to perform flow resistance status diagnosis based on the described flow resistance characterization status includes,

[0011] The output flow resistance characterization status does not perform flow resistance status diagnosis.

[0012] Alternatively, perform flow resistance status diagnosis and output the flow resistance status diagnosis results;

[0013] The method for diagnosing flow resistance includes:

[0014] Acquire inlet and outlet data of the resistive muffler. The inlet data includes inlet flow velocity, inlet air pressure, and inlet audio spectrum. The outlet data includes outlet flow velocity, outlet air pressure, and outlet audio spectrum.

[0015] The actual velocity difference is determined based on the absolute value of the difference between the inlet velocity and the outlet velocity, and the actual pressure difference is determined based on the absolute value of the difference between the inlet pressure and the outlet pressure.

[0016] The flow resistance characterization trend is determined based on the actual flow velocity difference and the actual air pressure difference.

[0017] The actual range of the silencing frequency and the regeneration frequency range are determined based on the inlet audio spectrum diagram and the outlet audio spectrum diagram.

[0018] The failure range of the silencing frequency is determined based on the actual range of the silencing frequency and the simulated range of the silencing frequency.

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

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

[0021] Obtain the inlet sound pressure level at each inlet measuring point of the resistive silencer, and determine the average inlet sound pressure level based on the average value of each inlet sound pressure level;

[0022] Obtain the outlet sound pressure level at each outlet measuring point of the resistive silencer, and determine the average outlet sound pressure level based on the average value of each outlet sound pressure level.

[0023] The actual noise reduction amount is determined based on the absolute value of the difference between the average inlet sound pressure level and the average outlet sound pressure level.

[0024] The number of inlet measuring points is equal to the number of outlet measuring points.

[0025] Furthermore, the method for determining the flow resistance characterization state of the resistive muffler based on the actual noise reduction amount includes,

[0026] Compare the actual noise reduction amount with the simulated range of the noise reduction amount;

[0027] The flow resistance characterization state is determined based on the comparison results, wherein,

[0028] If the actual noise reduction exceeds the noise reduction simulation range, the flow resistance characterization state is determined to be an abnormal flow resistance state.

[0029] If the actual noise reduction is within the noise reduction simulation range, then the flow resistance characterization state is determined to be a normal flow resistance state.

[0030] Further, based on the described flow resistance characterization status, it is determined whether to perform flow resistance status diagnosis, including...

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

[0032] If the flow resistance characterization state is an abnormal flow resistance state, then a flow resistance state diagnosis is performed and the flow resistance state diagnosis result is output.

[0033] Furthermore, the flow resistance characterization trend is determined based on the actual flow velocity difference and the actual air pressure difference, including:

[0034] If the actual flow velocity difference is greater than the simulated range of the flow velocity difference and the actual air pressure difference is greater than the simulated range of the air pressure difference, then the flow resistance characterization trend is determined to be an excessive flow resistance trend.

[0035] If the actual flow velocity difference is less than the simulated range of the flow velocity difference and / or the actual air pressure difference is less than the simulated range of the air pressure difference, then the flow resistance characterization trend is determined to be a trend of excessively low flow resistance.

[0036] Furthermore, the method for determining the actual range of the silencing frequency and the regeneration frequency range based on the inlet audio spectrogram and the outlet audio spectrogram includes,

[0037] The inlet audio range and the outlet audio range are determined based on the inlet audio spectrogram and the outlet audio spectrogram, respectively.

[0038] The actual range of the silencing frequency is determined based on the relative complement of the exit audio range to the inlet audio range.

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

[0040] Furthermore, the failure range of the silencing frequency is determined based on the absolute complement of the simulated range of the silencing frequency to the actual range of the silencing frequency.

[0041] Furthermore, methods for determining the flow resistance status diagnostic results of resistive mufflers include,

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

[0043] If both the silencing frequency failure range and the regeneration frequency range are high frequencies, then the determination that the flow resistance characterization trend is an excessive flow resistance trend is accurate, and the flow resistance status diagnosis result of the resistive silencer is determined to be excessive flow resistance.

[0044] If both the silencing frequency failure range and the regeneration frequency range are low frequencies, then the determination that the flow resistance characterization trend is a trend of excessively low flow resistance is accurate, and the flow resistance status diagnosis result of the resistive silencer is determined to be excessively low flow resistance.

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

[0046] The numerical simulation module is used to perform numerical simulations of the noise reduction 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 noise reduction frequency.

[0047] The data acquisition module is used to acquire the inlet sound pressure level, outlet sound pressure level, inlet flow velocity, inlet air pressure, outlet flow velocity, outlet air pressure, inlet audio data, and outlet audio data at each inlet measuring point of the resistive muffler; the data processing module, connected to the data acquisition module, is used to determine the average inlet sound pressure level based on the inlet sound pressure level at each inlet measuring point, determine the average outlet sound pressure level based on the outlet sound pressure level at each outlet measuring point, and determine the inlet audio spectrum and outlet audio spectrum based on the inlet audio data and the outlet audio data, respectively.

[0048] The flow resistance analysis module, connected to both the numerical simulation module and the data processing module, is used to determine the flow resistance characterization state of the resistive muffler based on the actual noise reduction amount to determine whether flow resistance state diagnosis is necessary. It determines the actual velocity difference based on the absolute value of the difference between the inlet and outlet flow velocities, the actual pressure difference based on the absolute value of the difference between the inlet and outlet air pressures, the flow resistance characterization trend based on the actual velocity difference and the actual air pressure difference, the actual range of the silencing frequency and the regeneration frequency range based on the inlet and outlet audio spectrum diagrams, the silencing frequency failure range based on the actual and simulated silencing frequency ranges, and the accuracy of the flow resistance characterization trend based on the silencing 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] The sound pressure level acquisition unit includes several sound level meters, used to acquire the inlet sound pressure level at each inlet measuring point of the resistive silencer and the outlet sound pressure level at each outlet measuring point.

[0051] A flow rate sensor unit is used to obtain the inlet and outlet flow rates of the resistive sensor.

[0052] A pressure sensor unit is used to obtain the inlet and outlet pressures of the resistive muffler;

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

[0054] Compared with the prior art, the beneficial effects of the present invention are that the flow resistance analysis method for environmental protection silencers provided by the present invention, through a combination of numerical simulation and actual measurement, can comprehensively and accurately evaluate the flow resistance state of resistive silencers, improve the accuracy of the silencing effect evaluation, and provide a reliable basis for the optimized design and maintenance of silencers.

[0055] Furthermore, this invention utilizes fluid dynamics calculation software and acoustic software to perform numerical simulations, determining the simulation range of noise reduction, flow velocity difference, air pressure difference, and silencing frequency, providing a theoretical reference for subsequent actual measurements; by comparing actual measured values ​​with simulated values, the performance of the muffler can be evaluated more accurately, reducing errors;

[0056] Furthermore, this invention determines the actual noise reduction amount by obtaining the inlet and outlet sound pressure levels of the resistive muffler to determine the flow resistance characterization state. Based on the flow resistance characterization state, it determines whether the flow resistance size is appropriate. If it is inappropriate, it considers the flow velocity difference and air pressure difference to preliminarily determine the flow resistance characterization trend (flow velocity too high / too low). It also comprehensively determines the accuracy of the flow resistance characterization trend based on the actual range of the silencing frequency and the regeneration frequency range. Thus, it can comprehensively, systematically and accurately evaluate the flow resistance state of the muffler.

[0057] Furthermore, based on the flow resistance status diagnosis results, the present invention can promptly identify problems with the silencer, providing a clear direction for the optimized design and maintenance of the silencer, which helps to improve the noise reduction effect and extend the service life of the equipment. Attached Figure Description

[0058] Figure 1 This is a flowchart illustrating the steps of the flow resistance analysis method for environmentally friendly mufflers according to an embodiment of the present invention.

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

[0060] Figure 3 A flowchart illustrating the steps for determining the actual range of the silencing frequency and the regeneration frequency range in an embodiment of the present invention;

[0061] Figure 4 This is a connection diagram of the flow resistance analysis system for the environmentally friendly muffler according to an embodiment of the present invention. Detailed Implementation

[0062] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0063] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0064] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0065] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0066] Please see Figure 1 and Figure 2 The figures shown are, respectively, a step diagram of the environmentally friendly muffler flow resistance analysis method according to an embodiment of the present invention and a flowchart of the environmentally friendly flow resistance status diagnosis according to an embodiment of the present invention. The present invention provides an environmentally friendly muffler flow resistance analysis method, including,

[0067] Step S1: Numerical simulation of the noise reduction process of the resistive muffler 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 noise reduction frequency. In practice, the same parameters as the actual detection process are input into the fluid dynamics calculation software and acoustic software to obtain the corresponding simulation range of noise reduction (this range is within the range that humans can hear), flow velocity difference, air pressure difference, and noise reduction frequency.

[0068] Step S2: Obtain the average inlet sound pressure level and average outlet sound pressure level of the resistive silencer to determine the actual noise reduction amount;

[0069] Step S3: Determine the flow resistance characterization state of the resistive muffler based on the actual noise reduction amount;

[0070] Step S4, determining whether to perform flow resistance status diagnosis based on the flow resistance characterization status, including:

[0071] The output flow resistance characterization status does not perform flow resistance status diagnosis.

[0072] Alternatively, perform flow resistance status diagnosis and output the flow resistance status diagnosis results;

[0073] The method for diagnosing flow resistance includes:

[0074] Acquire inlet and outlet data of the resistive muffler. The inlet data includes inlet flow velocity, inlet air pressure, and inlet audio spectrum. The outlet data includes outlet flow velocity, outlet air pressure, and outlet audio spectrum.

[0075] The actual velocity difference is determined based on the absolute value of the difference between the inlet velocity and the outlet velocity, and the actual pressure difference is determined based on the absolute value of the difference between the inlet pressure and the outlet pressure.

[0076] The flow resistance characterization trend is determined based on the actual flow velocity difference and the actual air pressure difference.

[0077] The actual range of the silencing frequency and the regeneration frequency range are determined based on the inlet audio spectrum diagram and the outlet audio spectrum diagram.

[0078] The failure range of the silencing frequency is determined based on the actual range of the silencing frequency and the simulated range of the silencing frequency.

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

[0080] It is understood that the flow resistance analysis method for environmentally friendly mufflers provided by this invention, through a combination of numerical simulation and actual measurement, can comprehensively and accurately evaluate the flow resistance state of resistive mufflers, improve the accuracy of the muffler effect evaluation, and provide a reliable basis for the optimized design and maintenance of mufflers. (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 measurement; then, by comparing the actual measured value and the simulation value, the performance of the silencer 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 silencer to determine the flow resistance characterization state, and the flow resistance characterization state is determined to determine whether the flow resistance size is appropriate. If it is inappropriate, the flow velocity difference and air pressure difference are considered to preliminarily determine the flow resistance characterization trend (flow velocity too large / too small), and the accuracy of the flow resistance characterization trend is determined by comprehensively considering the actual range of silencing frequency and the regeneration frequency range, so that the flow resistance state of the silencer can be evaluated comprehensively, systematically and accurately; (3) According to the flow resistance state diagnosis results, the problems of the silencer can be found in time, which can provide a clear direction for the optimization design and maintenance of the silencer, which helps to improve the silencing effect and extend the service life of the equipment; (4) By accurately evaluating and optimizing the flow resistance state of the silencer, noise pollution can be reduced and environmental quality can be improved.

[0081] It is understandable that noise reduction is a physical quantity that measures the degree to which noise reduction measures (such as using silencers, sound insulation materials, etc.) reduce noise. It reflects the difference in noise intensity before and after the measures are taken; that is, the degree to which the sound energy of a noise source is attenuated after noise reduction treatment under specific environmental and conditions. The unit is usually decibel (dB).

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

[0083] Step S21: Obtain the inlet sound pressure level at each inlet measuring point of the resistive silencer, and determine the average inlet sound pressure level based on the average value of each inlet sound pressure level;

[0084] Step S22: Obtain the outlet sound pressure level at each outlet measuring point of the resistive silencer, and determine the average outlet sound pressure level based on the average value of each outlet sound pressure level.

[0085] Step S23: Determine the actual noise reduction amount based on the absolute value of the difference between the average inlet sound pressure level and the average outlet sound pressure level;

[0086] The number of inlet measuring points is equal to the number of outlet measuring points.

[0087] Understandably, when measuring the average sound pressure level difference, each sound level meter is first placed at a suitable position on the inlet section of the silencer (at each inlet measuring point). For a stable noise source, multiple measuring points can be selected on the section (for example, on a circular pipe section, multiple points are selected at certain angular intervals and radius positions). Then, the microphone of the sound level meter is aligned with each measuring point in turn, and the sound pressure level at each measuring point is recorded. After the measurement is completed, the sound level meter uses its built-in statistical function or transmits the data to computer software for averaging calculation to obtain the average sound pressure level of the inlet section (average inlet sound pressure level). Then, the sound level meter is placed at a suitable position on the outlet of the silencer (at each outlet measuring point) and the same measurement operation is performed to obtain the average outlet sound pressure level. Finally, the actual noise reduction 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 inlet of the silencer is circular, the measuring points are usually arranged using the equal area circular ring method or the equal angle ray method. For the equal area circular ring method, the inlet cross section is divided into several concentric circular rings, and 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, several rays are radiated outward from the center of the circle, and measuring points are arranged at equal intervals on each ray. The number of rays is generally not less than 6. (2) Square or rectangular inlet: For square or rectangular inlet, the measuring points can be arranged using the grid method. The inlet cross section is divided into several equal small rectangular or square grids, and measuring points are arranged at the center of each grid. The size of the grid is determined according to the inlet size and measurement accuracy requirements. Generally, the grid side length is less than one-third of the inlet side length.

[0089] In practice, the measurement process includes: first, placing the sound level meter at each measuring point and ensuring that the microphone is pointing correctly (towards the sound source); then turning on the sound level meter and recording the sound pressure level readings at each measuring point.

[0090] In practice, a single sound level meter can be used to determine the sound pressure level at each measuring point individually.

[0091] Specifically, the method for determining the flow resistance characterization state of a resistive muffler based on the actual noise reduction amount includes,

[0092] Step S31: Compare the actual noise reduction amount with the simulated noise reduction range; it is understood that, in practice, the noise reduction amount is used to represent the noise reduction amount of the resistive muffler.

[0093] Step S32: Determine the flow resistance characterization state based on the comparison results, wherein,

[0094] If the actual noise reduction exceeds the simulated noise reduction range (in practice, the actual noise reduction is less than the simulated noise reduction range), then the flow resistance characterization state is determined to be an abnormal flow resistance state.

[0095] If the actual noise reduction is within the noise reduction simulation range, then the flow resistance characterization state is determined to be a normal flow resistance state.

[0096] It is understandable that flow resistance is closely related to noise reduction. When the flow resistance is moderate, sound waves can propagate and be absorbed well in the sound-absorbing material inside the muffler, which is beneficial to improving the noise reduction. In one implementation, under a certain airflow velocity, appropriate flow resistance can allow sound waves to pass evenly through the area filled with sound-absorbing material, allowing the sound-absorbing material to fully exert its sound absorption effect. However, if the flow resistance is too high, it will cause the airflow to form uneven flow inside the muffler. In one implementation, high-speed airflow channels may be generated in some local areas of the sound-absorbing material, preventing sound waves from fully contacting the sound-absorbing material, thereby reducing the sound absorption effect and reducing the noise reduction. Conversely, if the flow resistance is too low, it may mean that the filling density of the sound-absorbing material is insufficient or the muffler structure is too simple, which cannot effectively attenuate sound waves, also leading to insufficient noise reduction.

[0097] Specifically, determining whether to perform flow resistance status diagnosis based on the described flow resistance characterization status includes...

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

[0099] If the flow resistance characterization state is an abnormal flow resistance state, then 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 is less than the noise reduction simulation range, the flow resistance characterization state is determined to be abnormal. At this time, it is impossible to determine whether the flow resistance is too large or too small, so flow resistance state diagnosis is required.

[0100] Understandably, by comparing the actual noise reduction with the simulated noise reduction range to determine the flow resistance characterization status 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 status diagnosis. This will enable timely detection and resolution of muffler performance problems, improve noise control efficiency, optimize equipment maintenance strategies, and ensure the long-term stable operation of the muffler.

[0101] Specifically, determining the flow resistance characterization trend based on the actual flow velocity difference and the actual air pressure difference includes,

[0102] If the actual flow velocity difference is greater than the simulated range of the flow velocity difference and the actual air pressure difference is greater than the simulated range of the air pressure difference, then the flow resistance characterization trend is determined to be an excessive flow resistance trend. It can be understood that the airflow velocity will decrease significantly in the area with high flow resistance inside the muffler, so the flow velocity difference should be large; a large flow resistance will lead to a large pressure loss; therefore, when both the actual flow velocity difference and the actual air pressure difference are greater than the simulated range of the flow velocity difference and the actual air pressure difference are greater than the simulated range of the air pressure difference, the flow resistance characterization trend can be determined to be an excessive flow resistance trend; and at this time, the judgment of the flow resistance characterization trend is highly likely to be accurate, and is generally considered to be accurate; therefore, in implementation, its accuracy can be determined based on the silencing frequency failure range and the regeneration frequency range, or its accuracy can be left undetermined.

[0103] If the actual velocity difference is less than the simulated velocity difference range and / or the actual pressure difference is less than the simulated pressure difference range, then the flow resistance characterization trend is determined to be a trend of excessively low flow resistance. It is understood that inside the silencer, the airflow velocity in channels with lower local flow resistance may decrease or increase slightly, so the velocity difference should be smaller; smaller flow resistance will result in smaller pressure loss. Therefore, when the actual velocity difference is less than the simulated velocity difference range and / or the actual pressure difference is less than the simulated pressure difference range, the flow resistance characterization trend is determined to be a trend of excessively low flow resistance, and the accuracy of its flow resistance characterization trend needs to be determined based on the silencer frequency failure range and the regeneration frequency range.

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

[0105] Understandably, flow resistance also directly leads to pressure loss: when airflow passes through a resistive silencer, the flow resistance will create a pressure difference between the silencer's inlet and outlet; a larger flow resistance will cause a larger pressure loss, which means that power equipment such as fans or engines need to consume more energy to overcome this pressure difference and push the airflow through the silencer.

[0106] Understandably, by comprehensively considering the actual flow velocity difference and the actual air pressure difference, the flow resistance characteristic trend of the resistive muffler can be quickly and initially judged, providing a scientific basis for the performance evaluation, fault diagnosis and optimization of the muffler.

[0107] As is understandable, the horizontal axis of an audio spectrogram represents frequency, typically in Hertz (Hz); the vertical axis represents amplitude, commonly in decibels (dB). Through the spectrogram, the energy distribution of a signal at different frequencies can be analyzed.

[0108] Please see Figure 3 The diagram illustrates the steps for determining the actual range of the silencing frequency and the regeneration frequency range according to an embodiment of the present invention. Specifically, the method for determining the actual range of the silencing frequency and the regeneration frequency range based on the inlet audio spectrum and the outlet audio spectrum includes the following steps:

[0109] The inlet audio range and the outlet audio range are determined based on the inlet audio spectrogram and the outlet audio spectrogram, respectively.

[0110] The actual range of the silencing frequency is determined based on the relative complement of the exit audio range within the entrance audio range. In one embodiment, the entrance audio range is A and its corresponding interval is a1~a2, the entrance audio range is B and its corresponding interval is b1~b2, and the relative complement of the exit audio range within the entrance audio range is the part that belongs to the interval a1~a2 but does not belong to the interval b1~b2, denoted as c1~c2. Then, the interval c1~c2 is the actual range of the silencing frequency.

[0111] The regenerated frequency range is determined based on the relative complement of the input audio range to the output audio range. In one embodiment, the input audio range is A and its corresponding interval is a1 to a2, the input audio range is B and its corresponding interval is b1 to b2, and the relative complement of the output audio range to the input audio range is the part that belongs to the b1 to b2 interval but does not belong to the a1 to a2 interval, denoted as d1 to d2. Then, the d1 to d2 interval is the regenerated frequency range.

[0112] Specifically, the silencing frequency failure range is determined based on the absolute complement of the actual silencing frequency range and the simulated silencing frequency range.

[0113] In practice, the actual range of silencing frequencies should be a subset of the simulated range of silencing frequencies (because simulations are calculated based on ideal conditions and should perform better than the actual effect, i.e., the range of silencing frequencies should be larger). The absolute complement of the actual range of silencing frequencies to the simulated range of silencing frequencies is the silencing frequency failure range.

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

[0115] Specifically, methods for determining the flow resistance status diagnostic results of a resistive muffler include,

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

[0117] If both the silencing frequency failure range and the regeneration frequency range are high frequencies, then the determination that the flow resistance characterization trend is an excessive flow resistance trend is accurate, and the flow resistance status diagnosis result of the resistive silencer is determined to be excessive flow resistance.

[0118] If both the silencing frequency failure range and the regeneration frequency range are low frequencies, then the determination that the flow resistance characterization trend is a trend of excessively low flow resistance is accurate, and the flow resistance status diagnosis result of the resistive silencer is determined to be excessively low flow resistance.

[0119] Understandably, the effective noise reduction frequency range of a muffler varies depending on its flow resistance. Generally, a moderate flow resistance helps broaden the effective noise reduction frequency bandwidth. For resistive mufflers, the noise reduction effect on mid-to-high frequency noise is usually better; that is, when the flow resistance is appropriate, mid-to-high frequency sound waves can be better absorbed in the sound-absorbing material, while low-frequency sound waves can also be attenuated to some extent through appropriate reflection and interference. However, if the flow resistance is too high, high-frequency sound waves may be reflected and scattered inside the muffler, failing to effectively enter the sound-absorbing material, thus reducing the effective range of high-frequency noise reduction. Conversely, if the flow resistance is too low, the attenuation capability for low-frequency sound waves may be weak, resulting in ineffective treatment of low-frequency noise within the muffler, which also limits the effective noise reduction frequency range of the muffler.

[0120] Understandably, the magnitude of flow resistance directly affects the frequency characteristics of airflow-generated noise: a larger flow resistance often leads to an increase in high-frequency regenerated noise components. This is because, under high flow resistance, airflow turbulence and eddies are more likely to generate high-frequency vibrations in small-scale structures (such as the pores of sound-absorbing materials, thin-walled structures, etc.). Therefore, when the flow resistance is too large, the airflow inside the muffler will be more turbulent, easily generating turbulence and eddies. These unstable airflows will excite the vibration of internal components of the muffler (such as pipe walls, baffles, and sound-absorbing materials, etc.), thereby generating strong airflow-generated noise. In this case, measures such as adding high-frequency sound-absorbing materials can be used to reduce the noise in response to high-frequency regenerated noise. Conversely, when the flow resistance is small, the regenerated noise generated by the relatively stable airflow is relatively low in intensity, and the regenerated noise may be dominated by low-frequency components. This is because the relatively stable airflow mainly causes low-frequency vibrations in larger structural components (such as the muffler shell, large-area baffles, etc.). In this case, the resistive muffler should be repaired to tighten the various structural parts of the muffler.

[0121] In practice, when the flow resistance is too high, both the silencing frequency failure range and the regeneration frequency range should exhibit high-frequency characteristics. Conversely, when the flow resistance is too low, both the silencing frequency failure range and the regeneration frequency range should exhibit low-frequency characteristics. Therefore, by comprehensively considering the consistency between the silencing frequency failure range and the regeneration frequency range, the accuracy of the flow resistance characterization trend can be accurately determined.

[0122] It is understandable that by comprehensively considering the consistency between the silencing frequency failure range and the regeneration frequency range, the flow resistance characteristic trend of the resistive muffler can be accurately judged, providing 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 a single parameter in the traditional method, thus 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, so as 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 to quickly locate the cause of the fault and improve the maintenance efficiency; (3) Designers can adjust the structural parameters of the muffler, the selection and layout of the sound-absorbing materials, etc., in a targeted manner based on this information, so as to improve its silencing effect in a specific frequency range and improve the overall performance.

[0123] Please see Figure 4 The diagram shown is a connection diagram of the environmentally friendly muffler flow resistance analysis system according to an embodiment of the present invention. The present invention also provides an environmentally friendly muffler flow resistance analysis system, comprising:

[0124] The numerical simulation module is used to perform numerical simulations of the noise reduction 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 noise reduction frequency.

[0125] The data acquisition module is used to acquire the inlet sound pressure level at each inlet measuring point of the resistive silencer, the outlet sound pressure level at each outlet measuring point, the inlet flow velocity, the inlet air pressure, the outlet flow velocity, the outlet air pressure, the inlet audio data, and the outlet audio data.

[0126] A data processing module, connected to the data acquisition module, is used to determine the average inlet sound pressure level based on the inlet sound pressure level at each inlet measuring point, determine the average outlet sound pressure level based on the outlet sound pressure level at each outlet measuring point, and determine the inlet audio spectrum and outlet audio spectrum based on the inlet audio data and the outlet audio data, respectively.

[0127] The flow resistance analysis module, connected to both the numerical simulation module and the data processing module, is used to determine the flow resistance characterization state of the resistive muffler based on the actual noise reduction amount to determine whether flow resistance state diagnosis is necessary. It determines the actual velocity difference based on the absolute value of the difference between the inlet and outlet flow velocities, the actual pressure difference based on the absolute value of the difference between the inlet and outlet air pressures, the flow resistance characterization trend based on the actual velocity difference and the actual air pressure difference, the actual range of the silencing frequency and the regeneration frequency range based on the inlet and outlet audio spectrum diagrams, the silencing frequency failure range based on the actual and simulated silencing frequency ranges, and the accuracy of the flow resistance characterization trend based on the silencing 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] The sound pressure level acquisition unit includes several sound level meters, used to acquire the inlet sound pressure level at each inlet measuring point of the resistive silencer and the outlet sound pressure level at each outlet measuring point.

[0130] Understandably, a sound level meter is a commonly used acoustic measurement instrument that converts sound signals into electrical signals. Then, it processes and analyzes these electrical signals through its internal circuitry. Its core components include a microphone, amplifier, filter, and display unit. The microphone receives the sound signal and converts it into an electrical signal. The amplifier amplifies the electrical signal. The filter can be selected to measure different frequency ranges as needed. Finally, the display unit outputs the measurement results, including information such as sound pressure level.

[0131] A flow rate sensor unit is used to obtain the inlet and outlet flow rates of the resistive sensor.

[0132] A pressure sensor unit is used to obtain the inlet and outlet pressures of the resistive muffler;

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

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

[0135] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles 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 all fall within the scope of protection of the present invention.

[0136] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An environmentally friendly muffler flow resistance analysis method, characterized by, The application relates to a method for determining the flow resistance state of a resistive muffler. The method comprises the following steps: numerical simulation of the muffling process of the resistive muffler by fluid dynamics calculation software and acoustic software to determine the simulation range of the noise reduction amount, the simulation range of the flow velocity difference, the simulation range of the air pressure difference, and the simulation range of the muffling frequency; acquiring the average inlet sound pressure level and the average outlet sound pressure level of the resistive muffler to determine the actual noise reduction amount; determining the flow resistance 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 state, which comprises: outputting the flow resistance state and not performing flow resistance state diagnosis; or, performing flow resistance state diagnosis and outputting the flow resistance state diagnosis result; wherein the method for flow resistance state diagnosis comprises: acquiring the inlet data and the outlet data of the resistive muffler, wherein the inlet data comprises the inlet flow velocity, the inlet air pressure and the inlet audio frequency spectrum diagram, and the outlet data comprises the outlet flow velocity, the outlet air pressure and the outlet audio frequency spectrum diagram; determining the actual flow velocity difference according to the absolute value of the difference between the inlet flow velocity and the outlet flow velocity, and determining the actual air pressure difference according to the absolute value of the difference between the inlet air pressure and the outlet air pressure; determining the flow resistance state trend according to the actual flow velocity difference and the actual air pressure difference; determining the actual range of the muffling frequency and the range of the regenerative frequency according to the inlet audio frequency spectrum diagram and the outlet audio frequency spectrum diagram; determining the invalid range of the muffling frequency according to the actual range of the muffling frequency and the simulation range of the muffling frequency; determining the accuracy of the flow resistance state trend according to the invalid range of the muffling frequency and the range of the regenerative frequency to determine the flow resistance state diagnosis result of the resistive muffler; the method for determining the actual noise reduction amount comprises: acquiring 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; acquiring 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 the actual noise reduction amount according to the absolute value of the difference between the average inlet sound pressure level and the average outlet sound pressure level; 2. The environmentally friendly muffler flow resistance analysis method of claim 1, wherein, wherein the number of the inlet measuring points is equal to the number of the outlet measuring points. the method for determining the flow resistance state of the resistive muffler according to the actual noise reduction amount comprises: comparing the actual noise reduction amount with the simulation range of the noise reduction amount; determining the flow resistance state according to the comparison result, wherein: if the actual noise reduction amount exceeds the simulation range of the noise reduction amount, it is determined that the flow resistance state is an abnormal flow resistance state; 3. The environmentally friendly muffler flow resistance analysis method of claim 1, wherein, if the actual noise reduction amount is within the simulation range of the noise reduction amount, it is determined that the flow resistance state is a normal flow resistance state. determining whether to perform flow resistance state diagnosis according to the flow resistance state, which comprises: if the flow resistance state is a normal flow resistance state, it is determined not to perform flow resistance state diagnosis and the flow resistance state is outputted; 4. The environmentally friendly muffler flow resistance analysis method of claim 3, wherein, if the flow resistance state is an abnormal flow resistance state, it is determined to perform flow resistance state diagnosis and the flow resistance state diagnosis result is outputted. determining the flow resistance state trend according to the actual flow velocity difference and the actual air pressure difference, which comprises: if the actual flow velocity difference is greater than the simulation range of the flow velocity difference and the actual air pressure difference is greater than the simulation range of the air pressure difference, it is determined that the flow resistance state trend is an excessively large flow resistance trend. If the actual flow rate difference is less than the flow rate difference simulation range and / or the actual air pressure difference is less than the air pressure difference simulation range, it is determined that the flow resistance characterization trend is a flow resistance too small trend.

5. The environmentally friendly muffler flow resistance analysis method of claim 1, wherein, The method for determining the actual range of sound attenuation frequencies and the range of regeneration frequencies according to the inlet audio spectrum and the outlet audio spectrum comprises, determining an inlet audio range and an outlet audio range according to the inlet audio spectrum and the outlet audio spectrum respectively; determining the actual range of sound attenuation frequencies according to the relative complement of the inlet audio range in the outlet audio range; determining the range of regeneration frequencies according to the relative complement of the outlet audio range in the inlet audio range.

6. The environmentally friendly muffler flow resistance analysis method of claim 1, wherein, determining a sound attenuation frequency failure range according to the absolute complement of the actual range of sound attenuation frequencies in the simulation range of sound attenuation frequencies.

7. The environmentally friendly muffler flow resistance analysis method of claim 1, wherein, The method for determining the flow resistance state diagnosis result of a resistive muffler comprises, determining the accuracy of the flow resistance characterization trend according to the sound attenuation frequency failure range and the range of regeneration frequencies, wherein, if the sound attenuation frequency failure range and the range of regeneration frequencies both belong to high frequencies, the determination of the flow resistance characterization trend being a flow resistance too large trend is accurate, and the flow resistance state diagnosis result of the resistive muffler is determined to be flow resistance too large; if the sound attenuation frequency failure range and the range of regeneration frequencies both belong to low frequencies, the determination of the flow resistance characterization trend being a flow resistance too small trend is accurate, and the flow resistance state diagnosis result of the resistive muffler is determined to be flow resistance too small.

8. An environmental muffler flow resistance analysis system applying the environmental muffler flow resistance analysis method of any one of claims 1-7, characterized in that, a numerical simulation module is configured to perform numerical simulation on the sound attenuation process of the resistive muffler by fluid dynamics calculation software and acoustic software to determine the simulation range of noise reduction, the simulation range of flow rate difference, the simulation range of air pressure difference, and the simulation range of sound attenuation frequencies; a data acquisition module is configured to acquire the inlet sound pressure level at each inlet measuring point, 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 of the resistive muffler; a data processing module is connected to the data acquisition module and configured 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. The flow resistance analysis module is connected with the numerical simulation module and the data processing module respectively, and is used for determining a flow resistance state of the resistive muffler according to an actual noise reduction amount, determining whether to perform a flow resistance state diagnosis, determining an actual flow rate difference according to an absolute value of a difference between the inlet flow rate and the outlet flow rate, determining an actual air pressure difference according to an absolute value of a difference between the inlet air pressure and the outlet air pressure, determining a flow resistance state trend according to the actual flow rate difference and the actual air pressure difference, determining a noise elimination frequency actual range and a regeneration frequency range according to the inlet audio spectrum graph and the outlet audio spectrum graph, determining a noise elimination frequency failure range according to the noise elimination frequency actual range and the noise elimination frequency simulation range, and determining an accuracy of the flow resistance state trend according to the noise elimination frequency failure range and the regeneration frequency range to determine a flow resistance state diagnosis result of the resistive muffler.

9. The environmentally friendly muffler flow resistance analysis system of claim 8, wherein, The data collection module comprises, a sound pressure level acquisition unit comprising a plurality of sound level meters, and used for acquiring an inlet sound pressure level at each inlet measuring point of the resistive muffler and an outlet sound pressure level at each outlet measuring point; a flow rate sensor unit, used for acquiring an inlet flow rate and an outlet flow rate of the resistive muffler; an air pressure sensor unit, used for acquiring an inlet air pressure and an outlet air pressure of the resistive muffler; an audio sensor unit, used for acquiring inlet audio data and outlet audio data of the resistive muffler.

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