Loudspeaker array and method for increasing sound pressure level applied to a flow tube

Abstract

The application relates to the field of acoustic test technology, and discloses a loudspeaker array applied to a flow pipe and a method for improving a sound pressure level. A first module of the loudspeaker array comprises a first pipe, two skeleton perforated plates, two metal wire meshes and two first loudspeakers, and the first module is arranged in an overall up-down symmetry; a second module comprises a second pipe, two skeleton perforated plates, two metal wire meshes and two second loudspeakers, and the second module is arranged in an overall left-right symmetry; the metal wire meshes constitute main flow channel wall surfaces at openings; and the array configuration of the loudspeakers arranged in the "staggered symmetry" of the main flow pipe wall surfaces is realized. In the sound absorption capacity test, sound waves generated by the loudspeakers are guided into the main flow pipe, the phase control of the loudspeakers at different positions is realized, the sine sound wave peak-peak superposition is realized, and the sound pressure of the loudspeaker array output is effectively improved; and in particular, the problem that a high sound intensity sound source cannot be obtained due to the limited number of loudspeakers installed in a small-size cross-section flow pipe can be avoided.

Description

Technical Field

[0001] This invention relates to the field of acoustic testing technology applications, and discloses a loudspeaker array applied to a flow tube and a method for increasing the sound pressure level. Background Technology

[0002] The acoustic liner installed on the nacelle wall of an aircraft engine is a key component for controlling engine radiated noise. Testing the acoustic performance of the liner using a flow duct is a necessary step in the liner design process. In addition, the silencers of the exhaust duct equipment also need to be tested for their sound absorption capacity under different operating conditions (including noise sources of different intensities). During the testing process, generating stable sound waves with controllable amplitude in the flow duct is crucial.

[0003] Chinese invention patent CN113435028A discloses a "Method and Device for Measuring Acoustic Parameters of Acoustic Liners," proposing a method for measuring the acoustic impedance and transmission loss of acoustic liners under different flow velocities and incident sound pressure levels. It employs a small-section pipe advantageous for acoustic measurement, with an effective measurable frequency up to 6000Hz. However, this method and device require a stable sound source, but it does not mention the method of sound source generation. Chinese invention patent CN113532827A, "Acoustic Liner Comprehensive Performance Test Platform," discloses a device for measuring the acoustic impedance and aerodynamic drag of acoustic liners. This device uses a loudspeaker array as the test sound source. The main flow pipe of this device has a large cross-sectional size, allowing one loudspeaker to be arranged on each wall of the rectangular pipe, and four loudspeakers to be arranged in the same axial position. However, the large cross-section results in a lower maximum measurable frequency, failing to meet high-frequency testing requirements. The disclosure also does not mention the loudspeaker installation method, its impact on the flow field, or the phase control method. Summary of the Invention

[0004] The purpose of this invention is to provide a loudspeaker array applied to a flow tube and a method for improving the sound pressure level, which can effectively improve the sound pressure output of the entire loudspeaker array, and in particular, can avoid the problem that a high sound intensity sound source cannot be obtained due to the limited number of small-size cross-section flow tube loudspeakers installed.

[0005] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows: A loudspeaker array applied to a flow tube includes: The first module includes a first pipe that can be coaxially connected to the main pipe, and two first speakers disposed opposite each other on both sides of the first pipe, wherein the center line connecting the two first speakers intersects the center line of the first pipe perpendicularly. The second module includes a second pipe coaxially connected to the first pipe, and two second speakers disposed opposite each other on both sides of the second pipe. The center line connecting the two second speakers intersects the center line of the second pipe perpendicularly; and the center line connecting the two second speakers is perpendicular to the center line connecting the two first speakers. The first pipe has an opening at each installation position corresponding to the first speaker, and the second pipe has an opening at each installation position corresponding to the second speaker; the first speaker of the first module and the second speaker of the second model are respectively installed at the corresponding opening positions through a connecting component; the connecting component includes a skeleton perforated plate disposed on the opening, and the side of the skeleton perforated plate facing the corresponding opening is covered with a metal wire mesh to form the flow channel wall of the first pipe or the second pipe at the corresponding opening position.

[0006] Furthermore, the adapter assembly also includes an adapter section fixed at the corresponding opening position, the adapter section being provided with a straight section cavity corresponding to the opening, and the first speaker and the second speaker being installed at the end of the straight section cavity away from the opening.

[0007] Furthermore, the transition section is also provided with a boss that can extend into the corresponding opening, and the perforated plate of the skeleton is fixed on the boss.

[0008] Furthermore, a bypass sealing ring is provided at the contact position between the transition section and the corresponding first or second pipe.

[0009] Furthermore, the first pipe and the second pipe are coaxially fixedly connected by a flange mounting edge, and a main channel sealing ring is provided between the contact surfaces of the flange mounting edges of the first pipe and the second pipe.

[0010] To achieve the above-mentioned technical effects, the present invention also provides a method for improving the output sound pressure level. The method is based on the speaker array described above, applying a first excitation voltage to two first speakers of the first module and a second excitation voltage to two second speakers of the second module, wherein the first excitation voltage and the second excitation voltage are out of phase.

[0011] Furthermore, at least two speaker arrays are connected in series.

[0012] Furthermore, taking the excitation voltage of the first loudspeaker on the first pipe coaxially connected to the main pipe as a reference, the phase difference between the excitation voltages of the loudspeakers in other pipes and the reference excitation voltage is determined according to... Analysis yielded, among which For the first [type of sensor array] along the serial direction of the sensor array The phase difference between the loudspeaker excitation voltage on each pipe and the reference excitation voltage. For the speed of sound, The airflow velocity within the main duct, "This corresponds to the downstream and upstream propagation of sound waves in the direction of airflow, respectively. A "+" is used when the sound wave propagates downstream and a "-" is used when the sound wave propagates upstream." " The frequency of the sound waves produced simultaneously by all the speakers. For the first The perpendicular distance between the line connecting the centers of two speakers on the first pipe and the line connecting the centers of two first speakers on the first pipe.

[0013] Compared with existing technologies, the advantages of this invention are as follows: This invention uses an array configuration of loudspeakers arranged in an "alternating symmetrical" manner on the wall of the main flow pipe. During sound absorption testing, by guiding the sound waves generated by the loudspeakers into the main flow pipe, the phase control of loudspeakers at different positions is achieved to make the sinusoidal sound waves superimpose peak to peak, thereby effectively improving the sound pressure output of the entire loudspeaker array. In particular, it can avoid the problem of not being able to obtain a high sound intensity source due to the limited number of loudspeakers installed in small-section flow pipes. Attached Figure Description

[0014] Figure 1 This is a perspective view of the loudspeaker array applied to the flow tube in Example 1 or 2; Figure 2 This is a schematic diagram of the loudspeaker array structure applied to the flow tube in Example 1 or 2; Figure 3 This is a schematic diagram of the structure of the first module in Embodiment 1 or 2; Figure 4 This is a schematic diagram showing the installation position relationship between the first module and the second module in Embodiment 1 or 2; Among them, 1. First module; 101. First pipe; 102. First speaker; 2. Second module; 201. Second pipe; 202. Second speaker; 3. Perforated plate of skeleton; 4. Metal wire mesh; 5. Adapter section; 501. Straight section cavity; 502. Boss; 6. Bypass sealing ring; 7. Flange mounting edge; 8. Main channel sealing ring. Detailed Implementation

[0015] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0016] Example 1 See Figures 1 to 4 A loudspeaker array applied to a flow tube includes: The first module 1 includes a first pipe 101 that can be coaxially connected to the main pipe, and two first speakers 102 that are disposed opposite to each other on both sides of the first pipe 101. The center line connecting the two first speakers 102 intersects the center line of the first pipe 101 perpendicularly. The second module 2 includes a second pipe 201 coaxially connected to the first pipe 101, and two second speakers 202 disposed opposite to each other on both sides of the second pipe 201. The center line connecting the two second speakers 202 intersects the center line of the second pipe 201 perpendicularly; and the center line connecting the two second speakers 202 is perpendicular to the center line connecting the two first speakers 102. The first pipe 101 has an opening at the installation position corresponding to each first speaker 102, and the second pipe 201 has an opening at the installation position corresponding to each second speaker 202. The first speaker 102 of the first module 1 and the second speaker 202 of the second model are respectively installed at the corresponding opening positions via a connecting assembly. The connecting assembly includes a skeleton perforated plate 3 disposed on the opening. A metal mesh 4 is attached to the side of the skeleton perforated plate 3 facing the corresponding opening to form the flow channel wall of the first pipe 101 or the second pipe 201 at the corresponding opening position, ensuring that the flow channel wall is smooth and without bumps, so as to avoid the side branch straight section cavity 501 affecting the airflow quality of the flow channel. It should be noted that the skeleton perforated plate 3 and the metal mesh 4 can be replaced with other structures with gaps. The selection principle for the replacement structure here is: 1) Sound waves can penetrate this structure without significant attenuation; 2) The structure as a whole has a certain rigidity and can be regarded as a hard wall, thereby ensuring the smooth passage of airflow.

[0017] In this embodiment, the loudspeaker array includes a first module 1 and a second module 2. The first module 1 includes a first duct 101, two perforated skeleton plates 3, two wire meshes 4, and two first loudspeakers 102. The first module 1 is arranged symmetrically from top to bottom. The second module 2 includes a second duct 201, two perforated skeleton plates 3, two wire meshes 4, and two second loudspeakers 202. The second module 2 is arranged symmetrically from left to right. The wire meshes 4 form the main channel wall at the opening, realizing the array configuration of loudspeakers arranged in an "alternating symmetrical" manner on the main channel wall. During the sound absorption capacity test, an external signal generator produces a sinusoidal AC voltage excitation signal with a specific frequency and amplitude. After being amplified by a power amplifier, the signal is applied to two loudspeakers to make the corresponding loudspeakers emit sound waves. By guiding the sound waves generated by the loudspeakers into the main duct, the phase control of the loudspeakers at different positions is achieved to make the sinusoidal sound waves superimpose peak to peak, thereby generating high-intensity sound waves in the upstream or downstream duct. This effectively improves the sound pressure output of the entire loudspeaker array, and in particular, it can avoid the problem of not being able to obtain a high-intensity sound source due to the limited number of small-section cross-section duct loudspeakers installed.

[0018] Based on the same inventive concept, a method for improving the output sound pressure level is provided. This method, based on the aforementioned loudspeaker array, applies a first excitation voltage to the two first loudspeakers 102 of the first module 1 and a second excitation voltage to the two second loudspeakers 202 of the second module 2, wherein the first and second excitation voltages are out of phase. Specifically, by adjusting the phase difference between the excitation voltages of the first module 1 and the second module 2, the sound waves generated by the loudspeakers at different positions under various flow velocities can be superimposed at their peaks, effectively improving the sound pressure level output by the loudspeaker array. Furthermore, utilizing the modular design of the loudspeaker array, the number of modules can be increased or decreased according to actual needs (at least two loudspeaker arrays can be connected in series) to meet the high sound intensity requirements during testing.

[0019] Example 2 See Figures 1 to 4 A loudspeaker array for use in a flow channel is described in this embodiment. The loudspeaker array device includes a first module 1, a second module 2, and a main channel sealing ring 8. The first module 1 includes a first pipe 101, two transition sections 5, two perforated skeleton plates 3, two wire meshes 4, and two bypass sealing rings 6. The first module 1 is arranged symmetrically from top to bottom. The second module 2 has a similar structure and components to the first module 1 and is arranged symmetrically from left to right.

[0020] In this embodiment, the first module 1 and the second module 2 are coaxially connected via their respective flange mounting edges 7. A mounting groove is provided between the contact surfaces of each pair of mating flange mounting edges 7 to accommodate the main channel sealing ring 8. Similarly, a sealing groove is provided at the contact position between the transition section 5 and the corresponding first pipe 101 or second pipe 201 to accommodate the bypass sealing ring 6.

[0021] In this embodiment, the first pipe 101 has an opening at the installation position corresponding to each first speaker 102, and the second pipe 201 has an opening at the installation position corresponding to each second speaker 202. The transition section 5 also has a boss 502 that can extend into the corresponding opening. A straight cavity 501 is provided inside the boss 502, which can hold the skeleton perforated plate 3 and the metal mesh 4. The boss 502 extends to the inner wall of the main pipe, ensuring that the metal mesh 4 forms the flow channel wall of the first pipe 101 or the second pipe 201 at the corresponding opening position. In this embodiment, the holes in the skeleton perforated plate 3 can be circular, square, or rhomboid, etc., and the metal mesh 4 uses a small-diameter, high-density mesh. The cross-sectional shape and size of the straight cavity 501 of the transition section 5 are the same as the speaker throat. The transition section 5 is fixed to the speaker and the main pipe. By reasonably setting the size of the transition section 5, after the transition section 5 is tightened, the skeleton perforated plate 3 and the corresponding bypass sealing ring 6 can be pressed tightly.

[0022] In this embodiment, the form and size of the transition section 5 of the first module 1 or the second module 2 can be reasonably set according to the size of the loudspeaker. When the cross-sectional size of the main pipe is too small and the diameter of the loudspeaker is too large, the length of the straight cavity 501 of the transition section 5 can be increased, thereby extending the distance between the two loudspeakers arranged opposite each other and avoiding spatial position conflicts between the first module 1 and the second module 2.

[0023] In this embodiment, the cross-sections of the first pipe 101 and the second pipe 201 can be any shape such as rectangle or circle, as long as they are consistent with the mainstream pipe being tested. The corresponding fastening method and the shape of the perforated plate skeleton need to be set according to the inner wall surface of the pipe.

[0024] The loudspeaker array device in this embodiment can increase the number of loudspeakers in the entire device by connecting several first modules 1 and second modules 2, thereby generating the required high-intensity sound waves in the upstream or downstream duct. Here, upstream and downstream refer to the upstream and downstream directions of the airflow in the main duct, respectively.

[0025] The method for increasing the output sound pressure level in this embodiment is to input a voltage excitation source with a different phase to each module speaker based on the distance between different module speakers, the flow velocity in the pipe, and the local sound velocity. Specifically: Taking the excitation voltage of the first loudspeaker 102 on the first pipe 101 coaxially connected to the main pipe as a reference, the phase difference between the loudspeakers and excitation voltages of other pipes and the reference excitation voltage is determined according to... Analysis yielded, among which For the first [type of sensor array] along the serial direction of the sensor array The phase difference between the loudspeaker excitation voltage on each pipe and the reference excitation voltage. For the speed of sound, The airflow velocity within the main duct, "This corresponds to the downstream and upstream propagation of sound waves in the direction of airflow, respectively. A "+" is used when the sound wave propagates downstream and a "-" is used when the sound wave propagates upstream." " The frequency of the sound waves produced simultaneously by all the speakers. For the first The vertical distance between the line connecting the centers of the two speakers on the first pipe and the line connecting the centers of the two first speakers 102 on the first pipe 101.

[0026] It should be noted that the excitation voltages of the two speakers loaded on the same first module 1 or second module 2 are in phase.

[0027] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A loudspeaker array applied to a flow tube, characterized in that, include: The first module includes a first pipe that can be coaxially connected to the main pipe, and two first speakers disposed opposite each other on both sides of the first pipe, wherein the center line connecting the two first speakers intersects the center line of the first pipe perpendicularly. The second module includes a second pipe coaxially connected to the first pipe, and two second speakers disposed opposite each other on both sides of the second pipe. The center line connecting the two second speakers intersects the center line of the second pipe perpendicularly; and the center line connecting the two second speakers is perpendicular to the center line connecting the two first speakers. The first conduit has an opening at each mounting position corresponding to the first speaker, and the second conduit has an opening at each mounting position corresponding to the second speaker; The first speaker of the first module and the second speaker of the second module are respectively installed at the corresponding opening positions via an adapter assembly; the adapter assembly includes a skeleton perforated plate disposed on the opening, and a metal wire mesh is attached to the side of the skeleton perforated plate facing the corresponding opening to form the flow channel wall of the first pipe or the second pipe at the corresponding opening position.

2. The loudspeaker array according to claim 1, characterized in that, The adapter assembly further includes an adapter section fixed at the corresponding opening position, the adapter section being provided with a straight section cavity corresponding to the opening, and the first speaker and the second speaker being installed at the end of the straight section cavity away from the opening.

3. The loudspeaker array according to claim 2, characterized in that, The transition section is also provided with a boss that can extend into the corresponding opening, and the perforated plate of the skeleton is fixed on the boss.

4. The loudspeaker array according to claim 2, characterized in that, A bypass sealing ring is provided at the contact position between the transition section and the corresponding first or second pipe.

5. The loudspeaker array according to claim 1, characterized in that, The first pipe and the second pipe are coaxially fixedly connected by a flange mounting edge, and a main channel sealing ring is provided between the flange mounting edge contact surfaces of the first pipe and the second pipe.

6. A method for increasing output sound pressure level, the method being based on a loudspeaker array according to any one of claims 1-5, characterized in that, A first excitation voltage is applied to the two first speakers of the first module, and a second excitation voltage is applied to the two second speakers of the second module, wherein the first excitation voltage and the second excitation voltage are out of phase.

7. The method for increasing output sound pressure level according to claim 6, characterized in that, Connect at least two speaker arrays in series.

8. The method for increasing output sound pressure level according to claim 6 or 7, characterized in that, Taking the excitation voltage of the first loudspeaker on the first pipe coaxially connected to the main pipe as a reference, the phase difference between the excitation voltage of the loudspeakers in other pipes and the reference excitation voltage is determined according to... Analysis yielded, among which For the first [type of sensor array] along the serial direction of the sensor array The phase difference between the loudspeaker excitation voltage on each pipe and the reference excitation voltage. For the speed of sound, The airflow velocity within the main duct, "These correspond to the downstream and upstream propagation of sound waves in the direction of airflow, respectively. A "+" is used when the sound wave propagates downstream, and a "" is used when the sound wave propagates upstream." " The frequency of the sound waves produced simultaneously by all the speakers. For the first The perpendicular distance between the line connecting the centers of two speakers on the first pipe and the line connecting the centers of two first speakers on the first pipe.

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