A test analysis method for determining distribution of wind noise contribution of a vehicle

Abstract

The application provides a test analysis method for determining the distribution of automobile wind noise contribution, which comprises the following steps: arranging wind noise source sampling points around the outer surface of the whole vehicle body, arranging in-vehicle noise receiving points at the in-vehicle noise receiving positions of interest, designing and selecting at least two point arrangement schemes, selecting the point arrangement scheme with the optimal accurate test analysis result, making an isolation and absorption distribution cloud map according to the test data, performing a wind tunnel test through a planar microphone array wind noise source positioning, obtaining a planar array positioning result, calculating the wind noise contribution distribution and making a cloud map, and thus evaluating the distribution of the contribution of automobile wind noise to the in-vehicle receiving points along the vehicle body, so that a more real and accurate contribution distribution can be obtained, and a more accurate basis for the low wind noise design scheme of the automobile can be provided.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of automobile noise control, and particularly relates to the research on the contribution of automobile noise. BACKGROUND

[0002] With the progress of automobile technology and the improvement of people's living standards, automobile users have higher and higher requirements for the ride comfort of automobiles, and the noise level in the vehicle during driving has become an important indicator affecting user satisfaction. As one of the main noise sources of automobiles, wind noise becomes more obvious with the increase of vehicle speed. Usually, wind noise becomes significant at a speed of 80 kph or above and gradually becomes the dominant part of the noise perceived by people. Compared with other main noise sources of automobiles such as power noise and tire noise during driving, wind noise originates from the air outflow field during driving, and is distributed around almost the entire vehicle body surface. The distribution range is quite scattered, and how to determine the spatial distribution characteristics of the noise source and the contribution of the noise source at different positions to the perception of the driver and passenger after being isolated by the vehicle body becomes a unique problem of wind noise.

[0003] The current understanding of the distribution of wind noise in the relevant engineering field is not clear, and the targeted test analysis method is relatively lacking. The technique of testing wind noise with a microphone array during wind tunnel testing is widely used in this regard. The distribution cloud map given by this technique can reflect the sound source distribution characteristics of wind noise on the corresponding vehicle body surface. However, since the transmission paths of aerodynamic sound sources originating from different positions to the human ear are not the same, the degree of sound absorption and insulation by the vehicle body structure will be different. The sound source positioning cloud map obtained by testing outside the vehicle using a microphone array cannot truly reflect the distribution characteristics of the noise energy perceived by the driver and passenger around the vehicle body. SUMMARY

[0004] The purpose of the present application is to overcome the above-mentioned difficulties in understanding the distribution of the contribution of automobile wind noise, and to provide a test analysis method for determining the distribution of the contribution of automobile wind noise, evaluating the contribution of automobile wind noise to the receiving point in the vehicle along the vehicle body, and providing a more true and accurate basis for the low wind noise design scheme of the automobile.

[0005] To achieve the above-mentioned purpose, the technical solution of the present application is as follows:

[0006] The present application provides a test analysis method for determining the distribution of the contribution of automobile wind noise, which comprises the following steps:

[0007] Step 1, determination and arrangement of wind noise sound source sampling measurement points on the vehicle body surface and vehicle interior noise receiving points.

[0008] Step 2, sound transmission function test.

[0009] Step 3, production of sound absorption and insulation distribution cloud map.

[0010] Step 4, planar microphone array wind noise source positioning wind tunnel test, get planar array positioning results,

[0011] Step 5, wind noise contribution distribution calculation and cloud map making.

[0012] Preferably, in step 1, the distribution method is to arrange wind noise source sampling points around the entire vehicle body surface, and the sampling points are evenly distributed and cover the characteristics of each surface structure; arrange the in-vehicle noise receiving points at the in-vehicle noise receiving positions.

[0013] For relatively independent complete surface structures on the vehicle body, the distances between the sampling points are basically consistent, and the sampling points are distributed from the center to the edge; for the joints between different independent components, the sampling points should be evenly arranged along the joints. The in-vehicle noise receiving points are arranged at the in-vehicle noise receiving positions, which are usually the ear positions of the person beside the seat. Strictly speaking, the sampling point distribution and density should be selected as reasonably as possible to obtain the contribution distribution results that can best represent the actual situation.

[0014] Preferably, in step 1, at least two distribution schemes are designed and selected, and the specific method is to design two sets of sampling point schemes with different distribution densities according to the above method, and then perform step 2 to obtain the sound absorption and insulation distribution cloud map, compare the differences, and if the differences are significant and not within the acceptable range, further increase the sampling points and test again, and repeat the process until a set of sampling point scheme with insignificant differences is obtained. Take the set with fewer sampling points as the final arrangement standard, and the test analysis result is considered as the final accurate result.

[0015] Preferably, the sound transmission function test in step 2 is tested by using a volume sound source excitation method to test the sound transmission function from each vehicle body surface noise source sampling point to the receiving point. For each sampling point, the frequency band is iHz (usually the sound transmission function in the one-third octave frequency band is recorded as NRi.

[0016] The sound transmission function above takes dB as the unit, and its physical meaning is the noise attenuation after the sound transmission through the transmission medium and the sound absorption and insulation effect.

[0017] In specific implementation, there are two kinds of volume sound source arrangement methods:

[0018] One is to use the volume sound source to excite the vehicle body surface noise source sampling point as the excitation point of the sound transmission function test system, and arrange the microphone as the response point of the test system at the in-vehicle noise receiving point. Move the sound outlet of the volume sound source to test each sampling point.

[0019] Another approach involves using the sampling points of wind noise sources on the vehicle body surface as the response points of the sound transfer function (STF) testing system, and arranging microphones there. The noise receiving points inside the vehicle are used as the excitation points of the testing system, excited by a volumetric sound source. The microphones (or groups of microphones) are then moved to test each measurement point on the vehicle body surface. According to the reciprocity theorem of sound transmission, the STF results obtained by both methods are consistent. During testing, the distance between the volumetric sound source or microphone and the measurement points on the vehicle body surface should be fixed and appropriate.

[0020] Preferably, step 3, the creation of the sound absorption and sound insulation distribution cloud map, includes:

[0021] The test vehicle is digitally modeled so that each measuring point can be represented by a spatial coordinate system (mainly used for three-dimensional analysis, which can be used when there is three-dimensional data for locating sound sources in wind tunnel tests, so as to obtain a more accurate contribution and vehicle position relationship in combination with subsequent steps) or a planar coordinate system of side projections (a more simplified two-dimensional analysis), thus obtaining the position set of each measuring point in the coordinate system.

[0022] For a certain frequency band (usually one-third octave bands or the entire frequency band), the measured sound transfer function value NRi is correlated with the location coordinates to obtain the sound absorption and sound insulation (sound transfer function) distribution matrix;

[0023] The distribution matrix is ​​interpolated in the coordinate system to generate a distribution cloud map.

[0024] Overlay the photograph or simplified model of the test vehicle facing the analysis plane with the distribution cloud map, so that the measurement points on the coordinate system correspond to the positions on the picture, and retain the cloud map content inside the vehicle body. The value of any point on the map represents the noise attenuation of the sound source at that point on the vehicle body to the receiving point inside the vehicle for the frequency band being analyzed.

[0025] Preferably, step 5, the calculation of wind noise contribution distribution and cloud map creation, includes:

[0026] For a certain frequency band (usually one-third octave bands or the entire frequency band), the sound pressure level SPLi of the noise source at each measuring point is extracted based on the planar array positioning results. The sound transfer function test value NRi is subtracted to obtain the contribution decibel value of the wind noise source from the measuring point to the receiving point inside the vehicle. The contribution decibel value is correlated with the position coordinates to obtain the contribution distribution matrix.

[0027] Interpolate the distribution matrix in the coordinate system to create a distribution contour map;

[0028] Overlay a photograph or simplified model of the test vehicle facing the analysis plane with a distribution cloud map, so that the measurement points on the coordinate system correspond to the positions on the image, and retain the cloud map content inside the vehicle body. The value of any point on the map represents the decibel contribution of the wind noise generated at that point on the surface of the vehicle body in the analyzed frequency band to the receiving point inside the vehicle.

[0029] The advantages of this invention are as follows:

[0030] The above-described test and analysis method for determining the distribution of wind noise contribution in automobiles involves arranging wind noise source sampling points around the entire outer surface of the vehicle body and placing noise receiving points inside the vehicle at the noise receiving locations of interest. At least two sampling point design and selection processes are performed, and the optimal sampling point scheme for accurate test and analysis results is chosen. A sound insulation and absorption distribution cloud map is then created based on the test data. Furthermore, a wind tunnel test is conducted using a planar microphone array to locate the wind noise source, obtaining the planar array positioning results. Finally, the wind noise contribution distribution is calculated and a cloud map is created. This method assesses the distribution of wind noise contribution along the vehicle body at the receiving points inside the vehicle, providing a more realistic and accurate picture of the contribution distribution and offering a more accurate basis for low wind noise design schemes for automobiles. Attached Figure Description

[0031] Figure 1 This is a schematic diagram illustrating the implementation process of the test and analysis method described in this invention;

[0032] Figure 2 Schematic diagram of a sound transfer function testing device;

[0033] Figure 3 Schematic diagram of a wind tunnel test setup for locating noise sources;

[0034] Figure 4 Example of sound insulation and absorption distribution diagrams on three sides of a test vehicle in the 400Hz frequency band;

[0035] Figure 5 This is an example of the wind noise contribution distribution of a test vehicle in two frequency bands: 400Hz and 1250Hz. Detailed Implementation

[0036] Taking a certain model of test vehicle as an example, the present invention will be further described in conjunction with the accompanying drawings:

[0037] The main steps of the test and analysis method for determining the distribution of wind noise contribution in automobiles proposed in this invention include: determining and arranging sampling points for wind noise sources on the vehicle surface and noise receiving points inside the vehicle, sound transfer function testing, creating sound insulation and absorption distribution cloud maps, wind tunnel testing for locating wind noise sources using a planar microphone array, and calculating and creating wind noise contribution distribution cloud maps.

[0038] Specifically as follows:

[0039] Step 1: Determination and arrangement of sampling points for wind noise sources on the vehicle body surface and noise receiving points inside the vehicle:

[0040] For a specific vehicle model, noise excitation measurement points were arranged around the entire outer surface of the vehicle body. The measurement points were evenly distributed and covered the characteristics of each surface structure. For relatively independent and complete surface structures on the vehicle body, the spacing between the measurement points was basically the same, and measurement points were distributed from the center to the edge. Measurement points were evenly arranged at the seams between different independent components. Noise receiving points were arranged at the ear position next to the seats inside the vehicle. In order to make the distribution and density of the measurement points as reasonable as possible and to obtain the contribution distribution results that best represent the real situation, the distribution of measurement points was designed and selected multiple times. Specifically, two sets of measurement point schemes with different distribution densities were designed according to the above method, and step two was performed for each scheme to obtain sound insulation and absorption distribution cloud maps. The differences were compared. If the differences were significant and outside the acceptable range, the distribution of points was further densified and the test was repeated. This process was repeated until a set of distribution schemes with no significant differences was obtained. The set with fewer points was taken as the final standard for the arrangement method, and its test analysis results were considered to be the final accurate results.

[0041] Step 2, Sound Transfer Function Test:

[0042] The acoustic transfer function from the sampling point to the response point of wind noise sources on each vehicle body surface was tested using the volumetric sound source excitation method. The test setup is shown below. Figure 2 The microphones (groups) are placed inside the vehicle, while the volumetric sound source is placed outside the vehicle. The PC is connected to the volumetric sound source and the microphones respectively through the data acquisition front end.

[0043] The acoustic transfer function (AST) is expressed in one-third octave band form. For each measurement point, the AST at sub-band iHz is denoted as NRi. In this test, the sampling points of the wind noise source on the vehicle surface are used as the excitation points of the AST test system, excited by a volumetric sound source. The noise receiving points inside the vehicle are used as the response points of the test system, and a microphone is placed there. The sound source's emitting port is moved to test each measurement point. During the test, the distance between the volumetric sound source or microphone and the measurement point on the vehicle surface is fixed and appropriate.

[0044] Step 3: Creating a sound insulation and absorption distribution cloud map:

[0045] A digital model of the test vehicle is created. In this example, a two-dimensional model is used, allowing each measurement point to be represented by a planar coordinate system based on the projections of its sides, thus obtaining the position set [x, y] of each measurement point in the coordinate system. For each sub-band of the one-third octave band and the entire frequency band, the measured acoustic transfer function (NRi) values ​​are mapped to the position coordinates to obtain the sound absorption / insulation (acoustic transfer function) distribution matrix [x, y, NRi]. Interpolation of this distribution matrix in the planar coordinate system yields a distribution cloud map (see [link]). Figure 4Overlay a photograph or simplified model of the test vehicle facing the analysis plane with a distribution cloud map, so that the measurement points on the coordinate system correspond to the positions on the image. Only the cloud map content inside the vehicle body is retained. The value of any point on the map represents the noise attenuation of the sound source at that point on the vehicle body in the analyzed frequency band as it is transmitted to the receiving point inside the vehicle.

[0046] Step 4: Wind tunnel test for locating wind noise sources using a planar microphone array.

[0047] The test vehicle underwent routine external wind noise source localization testing in an acoustic wind tunnel. The testing setup is described below. Figure 3 The test vehicle was placed in an acoustic wind tunnel, and wind noise was obtained through a planar microphone array. The data was collected by a PC through a data acquisition front-end to obtain the planar array positioning results.

[0048] Step 5: Calculation of wind noise contribution distribution and creation of cloud map:

[0049] For each sub-band iHz of each one-third octave band, the sound pressure level SPLi of the noise source at each measuring point is extracted based on the planar array positioning results. Subtracting the measured sound transfer function value NRi yields the decibel contribution of the wind noise source from the measuring point to the in-vehicle receiving point in the iHz band. Mapping the measured values ​​to the location coordinates yields the contribution distribution matrix [x,y,SPLi-NRi]. Interpolating this distribution matrix in a planar coordinate system generates a distribution cloud map (see...). Figure 5 Overlay a photograph or simplified model of the test vehicle facing the analysis plane with a distribution cloud map, so that the measurement points on the coordinate system correspond to the positions on the image. Only the cloud map content inside the vehicle body is retained. The value at any point on the map represents the decibel contribution of wind noise generated at that point on the vehicle surface in the analyzed frequency band to the receiving point inside the vehicle.

[0050] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0051] It should be understood that the steps described in the method embodiments of this application may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of this application is not limited in this respect.

Claims

1. A test and analysis method for determining the distribution of wind noise contribution in automobiles, characterized in that, The method includes: Step 1: Determine and arrange sampling points for wind noise sources on the vehicle body surface and noise receiving points inside the vehicle; Step 2, Sound transfer function test: The sound transfer function from the sampling point to the receiving point of each noise source on the vehicle body surface is tested using the volumetric sound source excitation method. For each sampling point, the sound transfer function at frequency band iHz is denoted as NRi. Step 3, creating a sound absorption and sound insulation distribution cloud map, including: The test vehicle is digitally modeled to obtain the position set of each test point in the coordinate system; For a certain frequency band, the measured sound transfer function value NRi is correlated with the location coordinates to obtain the sound absorption and sound insulation distribution matrix; The distribution matrix is ​​interpolated in the coordinate system to generate a distribution cloud map; Overlay the test vehicle photograph or simplified model diagram facing the analysis plane with the distribution cloud map, so that the measurement points on the coordinate system correspond to the positions on the picture, retaining the cloud map content inside the vehicle body. The value of any point on the map represents the noise attenuation of the sound source at that point on the vehicle body to the receiving point inside the vehicle for the analyzed frequency band. Step 4: Wind tunnel test for locating wind noise sources using a planar microphone array to obtain the planar array location results; Step 5, wind noise contribution distribution calculation and cloud map creation, including: For a certain frequency band, the sound pressure level SPLi of the noise source at each measuring point is extracted based on the planar array positioning results. The sound transfer function test value NRi is subtracted to obtain the contribution decibel value of the wind noise source from the measuring point to the receiving point inside the vehicle. The contribution decibel value is correlated with the position coordinates to obtain the contribution distribution matrix. Interpolate the distribution matrix in the coordinate system to create a distribution contour map; Overlay a photograph or simplified model of the test vehicle facing the analysis plane with a distribution cloud map, so that the measurement points on the coordinate system correspond to the positions on the image, and retain the cloud map content inside the vehicle body. The value of any point on the map represents the decibel contribution of the wind noise generated at that point on the surface of the vehicle body in the analyzed frequency band to the receiving point inside the vehicle.

2. The test and analysis method for determining the distribution of vehicle wind noise contribution according to claim 1, characterized in that, In step 1, the sampling points are arranged as follows: wind noise source sampling points are arranged around the entire outer surface of the vehicle body, and the sampling points are evenly distributed and cover the characteristics of each surface structure; in-vehicle noise receiving points are arranged at the noise receiving locations of interest inside the vehicle.

3. The test and analysis method for determining the distribution of vehicle wind noise contribution according to claim 2, characterized in that, In step 1, at least two layout schemes are designed and selected: first, two layout schemes with different distribution densities are designed, and sound absorption and sound insulation distribution cloud maps are obtained by testing them respectively. Then, the differences are compared. If the difference exceeds the preset range, the layout is further densified and tested again. This process is repeated until a set of layout schemes with differences that meet the requirements is obtained. The set with fewer layouts is taken as the final layout standard.

4. The test and analysis method for determining the distribution of vehicle wind noise contribution according to claim 1, characterized in that, The coordinate system is either a spatial coordinate system or a planar coordinate system projected from each side.

5. The test and analysis method for determining the distribution of vehicle wind noise contribution according to claim 1, characterized in that, The frequency band mentioned is usually one-third octave bands of each sub-band or the entire frequency band.

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