Testing device and method for measuring full-angle frequency response characteristics of nose cone

Abstract

The invention relates to the technical field of nose cone frequency response characteristic testing, in particular to a testing device and method for measuring the full-angle frequency response characteristic of a nose cone, and the device comprises a microphone which is connected with a nose cone to be measured and is used for generating an acoustic signal; the rotatable microphone bracket is used for carrying a microphone; the standard sound source is used for generating sound waves with different preset frequencies and amplitudes; the standard sound source bracket is used for carrying a standard sound source; the data acquisition system is used for acquiring acoustic signals of the corresponding microphones when the rotatable microphone bracket rotates at different angles, generating a noise curve under the full angle of the nose cone, and normalizing the noise curve to generate frequency response curves of the nose cone under various angles; based on the testing device, the obtained full-angle frequency response characteristics can be comprehensively and accurately measured, the obtained nose cone acoustic characteristic testing data are more accurate, and specific use requirements are better met.

Description

Technical Field

[0001] The present invention relates to the technical field of testing frequency response characteristics of a nose cone, and in particular to a testing device and method for measuring the full-angle frequency response characteristics of a nose cone. Background Art

[0002] When an aircraft or other object is conducting an acoustic test in an acoustic wind tunnel laboratory, the test section is in the airflow area. In order to obtain accurate acoustic test data, a nose cone is often installed on the microphone in the test section to reduce the additional noise brought to the microphone by the flow of gas. Each nose cone has its own unique acoustic characteristics, and its acoustic characteristics are related to the wind speed, the frequency of the sound source, and the orientation of the sound source and the nose cone. The sound source frequency and the orientation of the sound source and the nose cone represent the frequency response characteristics of the nose cone in different sound wave input directions. In related technologies, the acoustic characteristics of the nose cone only consider the relationship between the nose cone and the wind speed, and do not consider the relationship between the sound source frequency and the orientation of the sound source and the nose cone, which brings errors to the test data and causes inaccurate test data.

[0003] The front end of the nose cone is a streamlined structure similar to a bullet head, in order to minimize air resistance and the disturbances generated. Installing this nose cone at the front end of the microphone can greatly reduce the noise generated by the airflow passing through the microphone by about 10dB, effectively reducing the self-noise of the microphone working in high-speed flowing gas. Each nose cone has its own unique acoustic characteristics. Even nose cones with the same structure will have different acoustic characteristics. Their acoustic characteristics are related to wind speed, sound source frequency, and the orientation of the sound source and nose cone. The relationship between acoustic characteristics and wind speed refers to the size of the self-noise generated by the nose cone at different incoming wind speeds. In the related art, in an acoustic wind tunnel laboratory, a microphone with a nose cone installed is placed in the mainstream area of ​​the airflow, and the noise spectrum of the microphone at different incoming wind speeds is measured, thereby obtaining the self-noise generated by the nose cone at different incoming wind speeds; the relationship between acoustic characteristics and sound source frequency refers to the frequency response characteristics of the nose cone; the relationship between acoustic characteristics and sound source orientation refers to the directivity of the nose cone.

[0004] In the related art, the acoustic characteristics of the nose cone only consider the self-noise of the nose cone, while ignoring the frequency response characteristics and directivity of the nose cone, resulting in low accuracy of the test results, and even completely wrong test results at certain sound incident angles and noise frequency bands. Summary of the invention

[0005] In view of this, the present invention provides a test device and method for measuring the full-angle frequency response characteristics of the nose cone, so as to solve the problem that the test data of the acoustic characteristics of the nose cone is inaccurate because the acoustic characteristics of the nose cone do not take into account the relationship between the sound source frequency and the orientation of the sound source and the nose cone.

[0006] In a first aspect, the present invention provides a test device for measuring the full-angle frequency response characteristics of a nose cone, comprising:

[0007] A microphone connected to the nose cone to be tested and used to generate an acoustic signal;

[0008] A rotatable microphone holder for carrying a microphone;

[0009] A standard sound source is set at a preset distance directly in front of the microphone and is used to generate sound waves of preset different frequencies and amplitudes;

[0010] Standard sound source bracket, used to carry standard sound source;

[0011] The data acquisition system is used to collect the acoustic signals of the microphone corresponding to different rotation angles of the rotatable microphone bracket, generate the noise curve at all angles of the nose cone, and normalize the noise curve to generate the frequency response curve of the nose cone at various angles.

[0012] Beneficial effects: The present invention provides a test device for measuring the full-angle frequency response characteristics of the nose cone. The rotatable microphone bracket can be used to achieve flexible adjustment of different angles. Combined with the data acquisition system to collect the acoustic signals of the microphone at various angles, the frequency response characteristics of the nose cone in the full angle range can be comprehensively and accurately obtained, which is helpful to understand in detail the specific situation of the nose cone's response to sound waves in various directions, and provide accurate angle-dependent data for subsequent related research, design optimization, etc. Configuring a standard sound source and setting it at a preset distance directly in front of the microphone can ensure that the generated sound waves have stable and known parameters such as frequency. With this as a reference, the input of sound waves during the measurement process is standardized and traceable, thereby improving the accuracy and reliability of the entire measurement result and facilitating comparative analysis between different measurements and different test devices; the digital acquisition system can not only collect acoustic signals to generate noise curves, but also further perform normalization processing to obtain frequency response curves at various angles. Based on the full-angle frequency response characteristics that can be comprehensively and accurately measured by the above-mentioned test device, the obtained nose cone acoustic characteristics test data is more accurate, and designers can clearly know the advantages and disadvantages of the acoustic performance of the nose cone at different angles, and then optimize and adjust the structure, materials and other aspects of the nose cone in a targeted manner. According to the test results of the nose cone acoustic characteristics, a nose cone that meets the requirements of the acoustic wind tunnel test is selected. At the same time, the acoustic wind tunnel test results are corrected according to the test results of the nose cone acoustic characteristics, so as to obtain accurate test data to better meet specific usage needs.

[0013] In an optional implementation, the distance between the standard sound source and the microphone is not less than a preset multiple of the wavelength of the sound wave of the standard sound source.

[0014] Beneficial effects: When the distance between the sound source and the microphone is close, a near-field effect will occur. When the distance between the standard sound source and the microphone is not less than the wavelength of the preset multiple of the sound wave of the standard sound source, the position of the microphone is closer to the far-field condition, which can avoid the interference of the complex relationship between sound pressure and particle velocity caused by the near-field effect, making the measured acoustic signal more consistent with the simple and stable propagation law in the far field. Under the same experimental conditions, the signal obtained each time is measured has high stability and repeatability, thereby improving the accuracy of the measurement.

[0015] In an optional embodiment, both the rotatable microphone holder and the standard sound source holder are wrapped with a sound-absorbing device.

[0016] Beneficial effects: The rotatable microphone bracket and the standard sound source bracket are both wrapped with a silencer, which can reduce the interference of the bracket on the sound field, optimize the measurement environment, and reduce the impact of background noise, thereby improving the accuracy and reliability of the measurement.

[0017] In a second aspect, the present invention provides a test method for measuring the full-angle frequency response characteristics of a nose cone based on the above test device, comprising:

[0018] The microphone with the nose cone is fixed to the rotatable microphone holder;

[0019] The sound wave frequency and the sound wave amplitude of the standard sound source are adjusted according to the preset sound wave frequency and the preset sound wave amplitude, and after stabilization, the acoustic signal of the microphone is continuously collected by the data acquisition system;

[0020] Rotate the rotatable microphone stand base to one circle at a preset constant angle, and use the data acquisition system to continuously collect microphone sound signals at different angles;

[0021] Adjust the sound wave frequency of the standard sound source, rotate the rotatable microphone stand base once again at a preset constant angle, and use the data acquisition system to continuously collect microphone acoustic signals at different angles;

[0022] The digital acquisition system collects microphone acoustic signals at different angles and at different frequencies to generate noise curves at all angles of the nose cone. The noise curves are normalized to generate frequency response curves of the nose cone at various angles.

[0023] Beneficial effect: Based on the above-mentioned test device, the present invention provides a test method for measuring the full-angle frequency response characteristics of the nose cone. By adding the nose cone to the microphone and rotating the microphone bracket base for one circle, the acoustic signal of the nose cone in the full angle range can be obtained. By adjusting the sound wave frequency and sound wave amplitude of the standard sound source and using a digital acquisition system to continuously collect microphone acoustic signals, the relationship between the acoustic characteristics of the nose cone and the sound source orientation and the sound wave frequency and sound wave amplitude of the standard sound source is obtained, and the noise curve at the full angle of the nose cone is generated, and the noise curve is normalized to generate the frequency response curve of the nose cone at each angle. Through the full-angle frequency response characteristics obtained by comprehensive and accurate measurement, the designer can clearly know the advantages and disadvantages of the acoustic performance of the nose cone at different angles, and then optimize and adjust the structure, material and other aspects of the nose cone in a targeted manner. According to the test results of the acoustic characteristics of the nose cone, the nose cone that meets the requirements of the acoustic wind tunnel test is selected, and the acoustic wind tunnel test results are corrected according to the test results of the acoustic characteristics of the nose cone, so as to obtain accurate test data to better meet specific usage requirements.

[0024] In an optional implementation, the sound wave frequency of the standard sound source is a preset octave center frequency of (1-20K) Hz.

[0025] Beneficial effect: The standard sound source frequency selects the preset octave center frequency of (1-20K) Hz. The preset octave (that is, the frequency range of each frequency band is a preset multiple of the center frequency) can provide fine frequency division, which can more effectively improve the measurement accuracy and analysis convenience for precise acoustic measurements.

[0026] In an optional implementation, the rotatable microphone stand base is rotated one circle at a preset constant angle, and a data acquisition system is used to continuously collect microphone sound signals at different angles, including:

[0027] The rotatable microphone holder base is rotated clockwise / counterclockwise at a preset constant angle for one circle. Each time it is rotated by one angle, the data acquisition system continuously collects the microphone sound signal to obtain the noise curve of the nose cone at the incident wave angle corresponding to the preset sound wave frequency and preset size of the standard sound source.

[0028] Beneficial effect: By rotating at a constant angle, it can be ensured that the microphone evenly collects sounds from different directions on a complete circle, and more comprehensive and uniform sound data can be obtained, thereby improving the representativeness and accuracy of the test results.

[0029] In an optional implementation, normalizing the noise curve includes:

[0030] The sound pressure value measured at the preset frequency is used as the reference value, and the ratio of the amplitude of the sound pressure values ​​measured at other frequencies on the noise curve to the sound pressure value measured at the preset frequency is used as the normalized value of other frequencies.

[0031] Beneficial effect: In the unnormalized noise curve, the absolute value of the sound pressure value will be affected by many factors. The normalization process can eliminate the dimensional influence of different characteristics and enhance numerical stability. Therefore, the normalized curve can more clearly show the changing trend of the nose cone frequency response characteristics.

[0032] In an optional implementation, the preset sound wave size does not exceed the measuring range of the microphone.

[0033] Beneficial effects: The range of a microphone refers to the maximum sound pressure level range that it can accurately capture and convert. If the size of the sound wave exceeds the range of the microphone, it may cause signal distortion or nonlinear response. The distortion will affect the accuracy of the measurement results and fail to truly reflect the characteristics of the sound field. Ensuring that the size of the sound wave does not exceed the range will help the microphone operate within its linear operating range and maintain the authenticity of the acoustic signal.

[0034] In an optional implementation, the test for measuring the full-angle frequency response characteristics of the nose cone is conducted in an anechoic chamber.

[0035] Beneficial Effects: The anechoic chamber provides a low-noise, non-reflective, environmentally stable test environment, which helps to eliminate interference from external noise and reflections, thereby improving the accuracy, reliability and stability of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 A test device for measuring the full-angle frequency response characteristics of the nose cone;

[0038] Figure 2 This is a schematic diagram of the nose cone;

[0039] Figure 3 is a schematic diagram of a microphone;

[0040] Figure 4 A schematic diagram of the microphone mounted on the nose cone;

[0041] Figure 5 is a schematic diagram of a rotatable bracket;

[0042] Figure 6 The test method flow for measuring the full-angle frequency response characteristics of the nose cone;

[0043] Figure 7 Typical 1 / 3 octave noise curve for the full angle of the nose cone;

[0044] Figure 8 It is the frequency response curve under a single preset angle;

[0045] Fig. 9 It is the 1 / 3 octave center.

[0046] Description of reference numerals:

[0047] 1. Microphone; 2. Rotatable microphone holder; 201. Microphone mounting support rod; 202. Holder rotation limiting mechanism; 203. Bearing; 204. Mounting support pillar; 205. Chassis with scale; 3. Standard sound source; 4. Standard sound source holder; 5. Data acquisition system. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0049] The full-angle frequency response characteristics of the nose cone refer to how to measure and analyze the frequency response of sound at different angles in acoustic research. The frequency response characteristics of the nose cone determine its sound response characteristics at different frequencies and directions. Understanding its full-angle frequency response characteristics is crucial to improving sound propagation, design optimization, and enhancing equipment performance.

[0050] The present invention provides a test device for measuring the full-angle frequency response characteristics of a nose cone, wherein a microphone is connected to a nose cone to be tested, and the nose cone to be tested is fixed while simulating the working state of the microphone in high-speed flowing gas; a standard sound source is used to generate sound waves with preset different frequencies and amplitudes to measure the acoustic signals of the microphone at different sound source frequencies, and a preset distance set in front of the microphone ensures that the standard sound source can be regarded as a point sound source; a standard sound source bracket is used to fix the standard sound source and provide structural support for the standard sound source; a data acquisition system is used to collect the acoustic signals of the microphone, and simultaneously generate a noise curve and a frequency response curve of the nose cone at various angles generated by normalizing the noise curve.

[0051] Combine the following Figures 1 to 9 , describing an embodiment of the present invention.

[0052] According to an embodiment of the present invention, in a first aspect, a test device for measuring the full-angle frequency response characteristics of a nose cone is provided, such as Figure 1 As shown, including:

[0053] Microphone 1 is connected to the nose cone to be tested and is used to generate acoustic signals. The main function of microphone 1 is to convert acoustic signals into electrical signals. Through its internal structure, the mechanical vibration of sound waves is converted into corresponding electrical signals, thereby achieving sound capture and transmission. Figure 2 As shown, the microphone is Figure 3 The microphone with the nose cone connected is shown in Figure 4 shown.

[0054] The rotatable microphone holder 2 is used to carry the microphone 1; the rotatable microphone holder 2 in the embodiment of the present invention is as follows Figure 5 As shown, it includes: a microphone mounting support rod 201, a support rotation limiting mechanism 202, a bearing 203, a mounting support column 204 and a chassis 205 with a scale. The bearing 203 is arranged at one end of the mounting support column 204, and the microphone mounting support rod 201 is arranged at the other end of the mounting support column 204. The support rotation limiting mechanism 202 is connected to the bearing 203. The chassis 205 with a scale is detachable. When the rotation angles of two adjacent tests are inconsistent or the frequency response characteristics of a single special angle are measured, for example, the angles required for two adjacent tests are 45° and 30° or a single rotation angle of 37° is required, it is only necessary to replace the chassis 205 with a scale, which can improve the convenience and speed of the test device. As an implementation form, the chassis 205 with a scale and the bearing 203 are an integrated structure; as another implementation form, the chassis 205 with a scale and the bearing 203 are single parts and are installed by matching. Generally, the microphone mounting support rod 201, the support rotation limiting mechanism 202 and the mounting support pillar 204 are an integrated structure.

[0055] The rotatable microphone holder 2 can conveniently adjust the angle of the microphone 1, so as to obtain sound waves measured in different directions and angles, which is crucial for capturing the omnidirectional sound field distribution of the sound source. The rotatable microphone holder 2 has a certain flexibility and can conveniently adjust the angle and position of the microphone 1 when needed. For different experimental requirements, researchers can quickly adjust the equipment configuration to perform sound field measurements in different directions and distances.

[0056] The standard sound source 3 is arranged at a preset distance in front of the microphone 1, and is used to generate sound waves of preset different frequencies and amplitudes; the standard sound source 3 provides a stable and known reference signal to ensure the accuracy, standardization and comparability of the acoustic measurement. The embodiment of the present invention adjusts the voltage of the signal generator in the standard sound source 3 and adjusts the frequency of the standard sound source 3 in combination with the power amplifier.

[0057] The standard sound source bracket 4 is used to carry the standard sound source 3; the standard sound source bracket 4 ensures that the standard sound source 3 maintains stable, safe and effective operation during the measurement or experiment process, and can effectively reduce the impact of external vibration on the standard sound source 3.

[0058] The data acquisition system 5 is used to collect the acoustic signals of the microphone 1 corresponding to different rotation angles of the rotatable microphone holder 2, generate the noise curve at all angles of the nose cone, and perform normalization processing on the noise curve to generate the frequency response curve of the nose cone at each angle;

[0059] The data acquisition system is a system that converts physical signals into digital signals and processes them. It can provide efficient and accurate real-time data acquisition and processing functions. The continuous acquisition time of the microphone 1 sound signal of the data acquisition system should be no less than 10s. The microphone is used as a device for capturing sound signals. Its output end is connected to the input end of the data acquisition system. It is usually physically connected through cables and other means to transmit the electrical signal converted by the microphone to the data acquisition system. For example, in a common condenser microphone, it converts the sound pressure change into a capacitance change, and then generates a changing voltage signal. This voltage signal is transmitted to the data acquisition system through a wire for subsequent processing. The data acquisition system may generate electromagnetic interference during operation. If this interference is too close to the microphone, it may affect the microphone's capture and conversion of sound signals. Therefore, in terms of layout, the data acquisition system is usually placed a certain distance away from the microphone, and measures such as electromagnetic shielding may be taken to reduce interference.

[0060] The test device provided by the embodiment of the present invention can realize flexible adjustment of different angles through the rotatable microphone bracket. Combined with the data acquisition system to collect the acoustic signals of the microphone at various angles, the frequency response characteristics of the nose cone in the full angle range can be comprehensively and accurately obtained, which is helpful to understand in detail the specific situation of the nose cone's response to sound waves in various directions, and provide accurate angle-dependent data for subsequent related research, design optimization, etc., and configure a standard sound source and set it at a preset distance directly in front of the microphone, which can ensure that the generated sound wave has stable and known parameters such as frequency, so that the input of the sound wave during the measurement process is standardized and traceable, thereby improving the accuracy and reliability of the entire measurement result, and facilitating comparative analysis between different measurements and different test devices; the data acquisition system can not only collect acoustic signals to generate noise curves, but also further perform normalization processing to obtain frequency response curves at various angles. Based on the full-angle frequency response characteristics that can be comprehensively and accurately measured by the above test device, the test data of the acoustic characteristics of the nose cone is more accurate, and the designer can clearly know the advantages and disadvantages of the acoustic performance of the nose cone at different angles, and then optimize and adjust the structure, materials, etc. of the nose cone in a targeted manner to better meet specific usage requirements.

[0061] In some embodiments, the distance between the standard sound source 3 and the microphone 1 is not less than a preset multiple of the wavelength of the sound wave of the standard sound source 3 .

[0062] In acoustic measurement, when the distance between the sound source and the microphone is close, a near-field effect will occur. The near field refers to an area very close to the sound source. In this area, the relationship between sound pressure and particle velocity is relatively complex and does not conform to the simple acoustic theory applicable in the far field. For example, for a simple point sound source, the sound pressure is inversely proportional to the distance in the far field, but this relationship does not hold true in the near field. Generally, the distance between the standard sound source 3 and the microphone 1 is not less than the multiple wavelength of the preset maximum sound wave of the standard sound source 3 (i.e., the wavelength corresponding to the lowest frequency). In this embodiment, the distance between the standard sound source 3 and the microphone 1 is not less than 2-3 wavelengths of the sound wave of the standard sound source 3, which can avoid the interference of the complex relationship between sound pressure and particle velocity caused by the near-field effect, so that the measured acoustic signal is more in line with the simple and stable propagation law in the far field. Under the same experimental conditions, the signal obtained each time has high stability and repeatability, thereby improving the accuracy of the measurement.

[0063] In some embodiments, both the rotatable microphone bracket 2 and the standard sound source bracket 4 are wrapped with a noise reduction device.

[0064] The rotatable microphone bracket 2 and the standard sound source bracket 4 may generate certain mechanical noise or vibration during operation. These interferences may affect the measurement accuracy of the microphone 1 or the signal quality of the standard sound source 3. By installing a silencer on the bracket, these unnecessary noise sources can be effectively isolated. At the same time, the reflection of sound waves can be effectively reduced, making the sound field more uniform, and improving the accuracy of the signal received by the microphone. The silencer is usually made of vibration-absorbing material, which can reduce the vibration of the bracket and the equipment itself, and prevent these vibrations from being transmitted to the microphone 1 or the standard sound source 3, thereby affecting the accuracy of the measurement data. In this embodiment, the silencer is a silencer cotton, which is only used as an example and is not limited to this.

[0065] In a second aspect, the present invention provides a test method for measuring the full-angle frequency response characteristics of the nose cone, such as Figure 6 As shown, including:

[0066] S1, fix the microphone with the nose cone on the rotatable microphone holder;

[0067] In the embodiment of the present invention, the rotatable microphone holder 2 enables the microphone 1 to be accurately positioned and adjusted at different angles and directions, and is suitable for omnidirectional sound wave collection. The rotatable design means that the measurement personnel can quickly adjust the position and direction of the microphone 1 to perform rapid measurement or experimental setup, thereby reducing the time and operation complexity of manual intervention. Combining the nose cone with the rotatable microphone holder 2 can ensure that the microphone 1 is accurately pointed to the standard sound source 3, thereby minimizing deviations or errors in the measurement process, while avoiding stray sounds or noises from other directions, ensuring signal clarity and accuracy. The fixed nose cone can ensure that the sound waves received by the microphone 1 are consistent during each measurement, thereby avoiding differences caused by changes in the position or angle of the microphone 1. By using a stable rotatable holder, the nose cone can always be maintained at the desired position, thereby reducing measurement deviations caused by inaccurate position, thereby improving the reliability of the test results.

[0068] S2, adjusting the sound wave frequency and sound wave amplitude of the standard sound source according to the preset sound wave frequency and preset sound wave amplitude, and continuously collecting the acoustic signal of the microphone by using the data acquisition system after stabilization;

[0069] The embodiment of the present invention adjusts the standard sound source according to the preset sound wave frequency and sound wave amplitude, thereby ensuring that the sound wave input of each experiment is stable and controllable. By adjusting the sound wave frequency and sound wave amplitude of the standard sound source 3, and continuously collecting the acoustic signal of the microphone using the digital acquisition system after it is stable, the acoustic test can be effectively carried out, the sound wave frequency and sound wave amplitude of the standard sound source are adjusted to ensure that the output signal of the standard sound source is stable, the digital acquisition system is used for continuous signal acquisition, and the data is stored in real time to ensure the accuracy of the test and the availability of the data.

[0070] S3, rotating the rotatable microphone stand base to one circle at a preset constant angle, and continuously collecting microphone sound signals at different angles using a data acquisition system;

[0071] The embodiment of the present invention can completely cover all angles around the nose cone by rotating the microphone bracket base for one circle, and can obtain the response of the nose cone to sound waves in all directions within a 360° range. By using a digital acquisition system to continuously collect sound signals at different angles, the dynamic response of the nose cone during the angle change process can be captured. In a practical environment, the sound wave environment faced by the nose cone is dynamically changing. For example, the angle of the front of the car (nose cone) will change with the steering during driving, and the direction of the surrounding noise source is also changing. In the field of aerospace, the nose cone of an aircraft will be subject to aerodynamic noise and engine noise from different directions during flight. This full-angle measurement can simulate various possible situations in flight and provide complete data support for analyzing the acoustic performance of the nose cone in different flight postures.

[0072] S4, adjusting the sound wave frequency of the standard sound source, rotating the rotatable microphone stand base again at a preset constant angle to one circle, and continuously collecting microphone acoustic signals at different angles using a data acquisition system;

[0073] The rotatable microphone holder 2 can adjust the direction of the sound source. By adjusting the sound wave frequency and sound wave amplitude of the standard sound source 3, the microphone acoustic signal is continuously collected by the digital acquisition system, so as to obtain the acoustic signals of the nose cone at different frequencies and all angles, and the relationship between the acoustic characteristics of the nose cone and the sound source direction and the sound wave frequency and sound wave amplitude of the standard sound source 3 is obtained, which helps to accurately locate the acoustic performance characteristics of the nose cone at different frequency-angle combinations.

[0074] S5, based on the data acquisition system, collects microphone sound signals at different angles and at different frequencies, generates noise curves at all angles of the nose cone, and normalizes the noise curves to generate frequency response curves of the nose cone at various angles.

[0075] The test method provided in the embodiment of the present invention can obtain the acoustic signal of the nose cone in the full angle range by adding the nose cone to the microphone and rotating the microphone bracket base for one circle, and also takes into account the conditions of different sound wave frequencies. In this way, the acoustic response of the nose cone at various frequencies and full angles can be described in detail, thereby improving the accuracy of the test data.

[0076] like Figure 7 The figure shows the noise curve at all angles of the nose cone when the sound wave frequency and sound wave amplitude of the standard sound source 3 are a single specific value; when the orientation of the microphone 1 and the standard sound source 3 is fixed, the frequency response curves corresponding to different sound wave frequencies and sound wave amplitudes of the standard sound source 3 are shown in FIG. Figure 8 shown.

[0077] In some embodiments, the sound wave frequency of the standard sound source is a preset octave center frequency of (1-20K) Hz.

[0078] In this embodiment, Fig. 9 As shown, the standard sound source 3 frequency selects the 1 / 3 octave center frequency of (1-20K) Hz for testing. The higher the accuracy of the nose cone frequency response curve, the smaller the octave. For example, the 1 / 6 octave, 1 / 12 octave or 1 / 24 octave center frequency can be selected. The standard sound source frequency selects the 1 / 3 octave center frequency of (1-20K) Hz. The 1 / 3 octave (that is, the frequency range of each frequency band is 1 / 3 of the center frequency) can provide a finer frequency division, which can more effectively improve the accuracy of measurement and the convenience of analysis for precise acoustic measurements.

[0079] In some embodiments, the rotatable microphone stand base is rotated at a preset constant angle for one circle, and a data acquisition system is used to continuously acquire microphone sound signals at different angles, including:

[0080] The rotatable microphone holder base is rotated clockwise / counterclockwise at a preset constant angle for one circle. Each time it is rotated by one angle, the data acquisition system continuously collects the microphone sound signal to obtain the noise curve of the nose cone at the incident wave angle corresponding to the preset sound wave frequency and preset size of the standard sound source.

[0081] In this embodiment, the preset constant angle is 30°. The finer the noise curve of the nose cone, the smaller the rotation angle of the bracket base. The rotation angle of the bracket base can be selected to be a smaller angle (should be a multiple of 360°), such as 15°. By rotating at a constant angle, it can be ensured that the microphone 1 evenly collects sounds from different directions on a complete circle, and more comprehensive and uniform sound data can be obtained, thereby improving the representativeness and accuracy of the test results.

[0082] In some embodiments, normalizing the noise curve includes:

[0083] The sound pressure value measured at the preset frequency is used as the reference value, and the ratio of the amplitude of the sound pressure values ​​measured at other frequencies on the noise curve to the sound pressure value measured at the preset frequency is used as the normalized value of other frequencies.

[0084] During the measurement process, due to factors such as the intensity of the sound source and the measurement environment, the absolute values ​​of the sound pressure measured at different frequencies may vary greatly. Normalization can eliminate this difference and unify different noise curves into a common standard range, so that different noise curves can be directly compared and analyzed. Normalization can eliminate the dimensional influence of different characteristics and enhance numerical stability. Therefore, the normalized frequency response curve can more clearly show the changing trend of the nose cone frequency response characteristics with frequency. The unnormalized noise curve may mask the real changes in the frequency response characteristics due to the fluctuation of the absolute sound pressure value.

[0085] In some embodiments, the preset sound wave size does not exceed the range of the microphone.

[0086] The range of microphone 1 refers to the maximum sound pressure level range that it can accurately capture and convert. If the size of the sound wave exceeds the range of microphone 1, it may cause signal distortion or nonlinear response. Distortion will affect the accuracy of the measurement results and cannot truly reflect the characteristics of the sound field. Ensuring that the size of the sound wave does not exceed the range will help the microphone operate within its linear operating range and maintain the authenticity of the acoustic signal. Within the range of microphone 1, there is a clear linear relationship between the output and the intensity of the sound wave. If the sound wave exceeds this range, the response of microphone 1 may become nonlinear, resulting in measurement errors. Ensuring that the sound wave does not exceed the range of microphone 1 can ensure that the relationship between its output and the sound wave intensity is accurate, thereby improving measurement accuracy.

[0087] In some embodiments, the test for measuring the full-angle frequency response characteristics of the nose cone is performed in an anechoic chamber.

[0088] In a conventional environment, sound waves are reflected by walls, floors and other objects, resulting in sound interference and complex reflection patterns. These reflected sounds may affect the accurate measurement of frequency response characteristics. In the anechoic chamber, due to its special design (such as sound-absorbing materials and structures), the reflection of sound waves is greatly reduced and the sound field tends to be uniform, thereby obtaining more realistic measurement results. The anechoic chamber provides a low-noise, non-reflective, and environmentally stable test environment, which helps to eliminate interference from external noise and reflections, thereby improving the accuracy, reliability, and stability of the test.

[0089] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the present invention.

Claims

1. A test device for measuring the full-angle frequency response characteristics of a nose cone, characterized in that: include: A microphone connected to the nose cone to be tested and used to generate an acoustic signal; A rotatable microphone holder for carrying the microphone; A standard sound source, arranged at a preset distance in front of the microphone, for generating sound waves of preset different frequencies and amplitudes; A standard sound source bracket, used for carrying the standard sound source; The data acquisition system is used to collect the acoustic signals of the microphone corresponding to different rotation angles of the rotatable microphone bracket, generate the noise curve at all angles of the nose cone, and normalize the noise curve to generate the frequency response curve of the nose cone at various angles.

2. The device according to claim 1, characterized in that The distance between the standard sound source and the microphone is not less than a preset multiple of the wavelength of the sound wave of the standard sound source.

3. The device according to claim 1, characterized in that The rotatable microphone bracket and the standard sound source bracket are both wrapped with a silencer.

4. A test method for measuring the full-angle frequency response characteristics of a nose cone, based on the test device according to any one of claims 1 to 3, characterized in that: include: The microphone with the nose cone is fixed to the rotatable microphone holder; The sound wave frequency and the sound wave amplitude of the standard sound source are adjusted according to the preset sound wave frequency and the preset sound wave amplitude, and after stabilization, the acoustic signal of the microphone is continuously collected by the data acquisition system; Rotate the rotatable microphone stand base to one circle at a preset constant angle, and continuously collect microphone sound signals at different angles using a data acquisition system; Adjust the sound wave frequency of the standard sound source, rotate the rotatable microphone stand base once again at a preset constant angle, and continuously collect microphone acoustic signals at different angles using a data acquisition system; The data acquisition system collects microphone sound signals at different angles and at different frequencies to generate noise curves at all angles of the nose cone, and the noise curves are normalized to generate frequency response curves of the nose cone at various angles.

5. The test method for measuring the full-angle frequency response characteristics of the nose cone according to claim 4, characterized in that: The sound wave frequency of the standard sound source is a preset octave center frequency of (1-20K) Hz.

6. The test method for measuring the full-angle frequency response characteristics of the nose cone according to claim 4, characterized in that: The method of rotating the rotatable microphone support base at a preset constant angle for one circle and continuously collecting microphone sound signals at different angles using a data acquisition system comprises: The rotatable microphone holder base is rotated clockwise / counterclockwise at a preset constant angle to complete one circle. Each time it rotates an angle, the data acquisition system continuously collects microphone sound signals to obtain the noise curve of the nose cone of the standard sound source at the incident wave angle corresponding to the preset sound wave frequency and preset size.

7. The test method for measuring the full-angle frequency response characteristics of the nose cone according to claim 4, characterized in that: The normalizing process of the noise curve includes: The sound pressure value measured at the preset frequency is used as the reference value, and the ratio of the amplitude of the sound pressure values ​​measured at other frequencies on the noise curve to the sound pressure value measured at the preset frequency is used as the normalized value of other frequencies.

8. The test method for measuring the full-angle frequency response characteristics of the nose cone according to claim 4, characterized in that: The preset sound wave size does not exceed the measuring range of the microphone.

9. The test method for measuring the full-angle frequency response characteristics of the nose cone according to any one of claims 4 to 8, characterized in that: The test for measuring the full-angle frequency response characteristics of the nose cone is carried out in an anechoic chamber.

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