Performance test method of sound absorption material for underwater vehicle

Abstract

A performance test method of a sound absorption material for an underwater vehicle comprises the following steps that an elastic material meeting the sound absorption performance is selected, a plate-shaped sample piece is manufactured, one side of the plate-shaped sample piece is a first test face, and a first sensor mounting hole penetrating through the first test face is formed; the plate-shaped sample piece is assembled on the rigid sample piece, a plate-shaped body of the rigid sample piece is provided with a second test surface and a second sensor mounting hole penetrating through the second test surface, and the first test surface is flush with the second test surface; installing a first pulsating pressure sensor and a second pulsating pressure sensor; the plate-shaped body is fixedly mounted on the side wall of the circulating water tank, and the first sensor mounting hole is located at the downstream of the second sensor mounting hole; the first pulsating pressure sensor detects the pulsating pressure of water located on the first testing face, the second pulsating pressure sensor detects the pulsating pressure of water located on the second testing face, and therefore the performance of the sound absorption material can be tested and evaluated more comprehensively.

Description

Technical Field

[0001] This invention relates to the field of stealth technology for underwater vehicles, and in particular to a method for testing the performance of sound-absorbing materials for underwater vehicles. Background Technology

[0002] Underwater vehicles with acoustic stealth capabilities are important naval equipment. The sound-absorbing materials applied to the hull surface of these vehicles play a crucial role in suppressing target intensity and enhancing stealth capabilities. Therefore, the selection and application of sound-absorbing materials have always been a key focus of research in this field.

[0003] Currently, the selection process for sound-absorbing materials typically prioritizes their acoustic shielding performance. This performance evaluation is generally conducted under laboratory conditions. Specifically, material samples are placed in a deep-tube testing device to simulate a hydrostatic pressure environment. Sound waves are emitted through an active noise source, and a hydrophone array is positioned on the other side of the material to detect the intensity of the transmitted sound waves. The sound absorption coefficient of the material is then calculated, serving as the primary basis for evaluating its sound wave shielding capability. High-performance sound-absorbing materials selected based on this standard are considered to effectively reduce the acoustic signature of underwater vehicles.

[0004] However, the applicant discovered in actual engineering applications that even some sound-absorbing materials that showed excellent shielding performance in the laboratory may induce significant "self-noise" problems when applied to the surface of real underwater vehicles or their scaled-down models, failing to achieve the expected stealth effect and affecting the design and manufacturing of underwater vehicles.

[0005] Therefore, the current material evaluation system cannot fully reflect the comprehensive acoustic behavior of sound-absorbing materials under real navigation conditions, and has obvious technical limitations. There is an urgent need to establish a more comprehensive material performance evaluation method. Summary of the Invention

[0006] In response to the shortcomings of the existing production technology, the applicant provides a performance testing method for sound-absorbing materials used in underwater vehicles, thereby enabling a more comprehensive evaluation of the performance of sound-absorbing materials.

[0007] The technical solution adopted in this invention is as follows: A method for testing the performance of sound-absorbing materials for underwater vehicles includes the following steps: Select an elastic material that meets the sound absorption performance and make a plate-shaped sample. One side of the plate-shaped sample is the first test surface, and the plate-shaped sample is provided with a first sensor mounting hole that penetrates the first test surface. A plate-shaped sample is assembled onto a rigid sample. The rigid sample includes a plate-shaped body with a groove on it. A second test surface is provided on the side of the plate-shaped body with the groove. When the plate-shaped sample is assembled onto the rigid sample, the plate-shaped sample is sealed to the groove. The first test surface is flush with the second test surface. A second sensor mounting hole penetrating the second test surface is provided on the plate-shaped body. A first pulsating pressure sensor is installed in the first sensor mounting hole, and a second pulsating pressure sensor is installed in the second sensor mounting hole. The plate-shaped body is fixedly installed on the side wall of the circulating water tank, and the second test surface is flush with the inner wall of the circulating water tank. The first sensor mounting hole is located downstream of the second sensor mounting hole. The water in the circulating water tank is made to flow at a predetermined flow rate and a predetermined pressure. The first pulsating pressure sensor detects the pulsating pressure of the water located at the first test surface, and the pulsating pressure value is T. The second pulsating pressure sensor detects the pulsating pressure of the water located at the second test surface, and the pulsating pressure value is G1.

[0008] As a further improvement to the above technical solution: The plate-shaped body is provided with a third sensor mounting hole that penetrates the second test surface. The third sensor mounting hole is located downstream of the first sensor mounting hole. The third sensor mounting hole is used to install a third pulsating pressure sensor. When the water in the circulating water tank flows at a predetermined flow rate and a predetermined pressure, the third pulsating pressure sensor detects the pulsating pressure of the water at the second test surface. The pulsating pressure value is G2.

[0009] A tubular sensor adapter is threaded into the first sensor mounting hole, the second sensor mounting hole, and the third sensor mounting hole. The first pulsating pressure sensor is connected to the inner thread of the sensor adapter in the first sensor mounting hole. The second pulsating pressure sensor is connected to the inner thread of the sensor adapter in the second sensor mounting hole; The inner hole of the sensor adapter in the third sensor mounting hole is threaded to the third pulsating pressure sensor.

[0010] The sensor adapter includes a tubular body, with one axial end of the tubular body facing the inside of the circulating water tank having a threaded outer surface, and the other axial end of the tubular body facing the outside of the circulating water tank having a fastening joint.

[0011] The plate-shaped body is provided with a first clearance hole corresponding to the mounting hole of the first sensor, and the diameter of the first clearance hole is [missing information]. ,

[0012] in, Where is the mounting diameter of the first pulsating pressure sensor, and E is the elastic modulus of the elastic material. The density of the elastic material, For elastic materials, Poisson's ratio The thickness of the plate-shaped sample. The lowest frequency among the frequencies of interest in the experiment. The maximum allowable deflection of the plate-shaped sample. This represents the pressure acting on the plate-shaped sample.

[0013] The plate-shaped body is provided with a second clearance hole corresponding to the first sensor mounting hole. One end of the second clearance hole penetrates the bottom surface of the groove, and the other end of the second clearance hole penetrates the side of the plate-shaped body away from the groove. After the first pulsating pressure sensor is installed on the first sensor mounting hole, the support base is installed on the second clearance hole. The first clearance hole is located on the support base and is directly opposite the first pulsating pressure sensor. The support base is in contact with the surface of the plate-shaped sample.

[0014] The support base is cylindrical. When the support base is installed on the second clearance hole, the outer circumferential surface of the support base is threadedly connected to the inner wall surface of the second clearance hole.

[0015] A third clearance hole is provided on the plate-shaped body of the rigid sample. The third clearance hole is a blind hole that is away from the second test surface. The second sensor mounting hole is directly opposite a third clearance hole and penetrates through the bottom of the third clearance hole.

[0016] The number of mounting holes for the first sensor is greater than or equal to two.

[0017] The mounting holes for the multiple first sensors are arranged in a straight line along the direction of water flow in the circulating water tank.

[0018] The beneficial effects of this invention are as follows: This invention features a compact and reasonable structure and is easy to operate. By ensuring that the sound absorption performance of the sound-absorbing material meets the requirements, a plate-shaped sample is made using the sound-absorbing material. The plate-shaped sample is then assembled with a rigid sample and placed simultaneously in a circulating water tank. The pulsating pressure of the water at different material properties is measured, thereby comparing and evaluating the hydrodynamic noise performance of the sound-absorbing material. This further narrows down the selection range of sound-absorbing materials and avoids the increase in self-noise of the vehicle after applying sound-absorbing materials, allowing for a more comprehensive test and evaluation of the performance of sound-absorbing materials.

[0019] Furthermore, the present invention also has the following advantages: (1) Pulsating pressure sensors are set on the rigid samples upstream and downstream of the plate-shaped sample made of sound-absorbing material. Two comparative tests are formed on the rigid sample, which can simultaneously test whether the sound-absorbing material will extend the suppression effect of pressure pulsation to the downstream structure. This makes it easier to select the sound-absorbing material with the best performance and optimize the layout design of the sound-absorbing material of the aircraft. The assembly structure of the rigid sample and the plate-shaped sample is simple and easy to install the sensors.

[0020] (2) A sensor adapter is set up to indirectly connect the pulsating pressure sensor to the plate-shaped sample or the rigid sample via a thread. The connection of the three types of components greatly reduces the probability of resonance caused by mechanical vibration, improves the accuracy of the pulsating pressure test, and reduces the design difficulty. In addition, compared with the first pulsating pressure sensor being directly threaded to the first sensor mounting hole 21, the connection thread depth with the first sensor mounting hole is increased by the sensor adapter, which improves the strength of the first pulsating pressure sensor mounting structure.

[0021] (3) Taking into account the performance of the elastic material and the installation requirements in the test, the upper and lower limits of the diameter of the first clearance hole are reasonably set. Under the premise of meeting the installation requirements, the elastic material can maintain its own elastic performance while being able to withstand pressure, so as to accurately measure the corresponding water pulsation pressure of the elastic material.

[0022] (4) While ensuring that the size of the first clearance hole meets the requirements, a second clearance hole and a support seat that can be detachably connected to the second clearance hole are set on the rigid sample. The first clearance hole is set on the support seat. After the first pulsating pressure sensor is installed, the outer periphery of the measuring part of the plate sample is rigidly supported. When the size of the first clearance hole is small and the thickness of the rigid sample is large, the test conditions are met while improving the convenience of operation. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention.

[0024] Figure 2 This is a schematic diagram (exploded view) of the structure of the present invention.

[0025] Figure 3 This is a schematic diagram of the assembly structure of the plate-shaped sample and the rigid sample of the present invention.

[0026] Figure 4 This is a schematic diagram of the assembly structure of the plate-shaped sample and the rigid sample of the present invention (bottom view).

[0027] Figure 5 This is a schematic diagram (sectional view) of the assembly structure of the plate-shaped sample and the rigid sample of the present invention.

[0028] Figure 6This is a schematic diagram (I) of the assembly process of the plate-shaped sample and the rigid sample of the present invention.

[0029] Figure 7 This is a schematic diagram (II) of the assembly process of the plate-shaped sample and the rigid sample of the present invention.

[0030] Figure 8 This is a schematic diagram of the assembly structure of the sensor adapter and the first pulsating pressure sensor of the present invention.

[0031] in: 1. Circulating water tank; 11. Installation window; 2. Plate-shaped sample; 20. First test surface; 21. First sensor mounting hole; 3. First pulsating pressure sensor; 4. Rigid sample; 40. Second test surface; 41. Second sensor mounting hole; 42. Groove; 43. Third clearance hole; 44. Plate-shaped body; 45. Third sensor mounting hole; 46. Second clearance hole; 5. Second pulsating pressure sensor; 6. Sensor adapter; 60. Tubular body; 61. Threaded surface; 62. Fastening connector; 7. Support base; 71. First clearance hole; 72. Insertion hole; 8. Third pulsating pressure sensor. Detailed Implementation

[0032] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0033] Example 1: The performance testing method for sound-absorbing materials used in underwater vehicles according to this embodiment includes the following steps: Prepare the materials to be tested: such as Figure 1 As shown, an elastic material that meets the sound absorption performance is selected and a plate-shaped sample 2 is made. One side of the plate-shaped sample 2 is the first test surface 20, and the plate-shaped sample 2 is provided with a first sensor mounting hole 21 that penetrates the first test surface 20. Assemble the material to be tested: Assemble the plate-shaped sample 2 onto the rigid sample 4. The rigid sample 4 includes a plate-shaped body 44, a groove 42 on the plate-shaped body 44, and a second test surface 40 on the side of the plate-shaped body 44. When the plate-shaped sample 2 is assembled onto the rigid sample 4, the plate-shaped sample 2 and the groove 42 are sealed together. The first test surface 20 and the second test surface 40 are flush. The plate-shaped body 44 is provided with a second sensor mounting hole 41 that penetrates the second test surface 40. Install sensors: such as Figures 3-5 As shown, a first pulsating pressure sensor 3 is installed in the first sensor mounting hole 21, and a second pulsating pressure sensor 5 is installed in the second sensor mounting hole 41. Place the material to be tested in the test environment: such as Figures 1-2 As shown, the plate-shaped body 44 is fixedly installed on the side wall of the circulating water tank 1, and the second test surface 40 is flush with the inner wall of the circulating water tank 1. The first sensor mounting hole 21 is located downstream of the second sensor mounting hole 41. Performance test: Water in the circulating water tank 1 is made to flow at a predetermined flow rate and a predetermined pressure. The first pulsating pressure sensor 3 detects the pulsating pressure of the water located at the first test surface 20, and the pulsating pressure value is T. The second pulsating pressure sensor 5 detects the pulsating pressure of the water located at the second test surface 40, and the pulsating pressure value is G1.

[0034] Elastic materials that meet sound absorption requirements can absorb sound waves emitted by sonar, thus achieving a stealth effect during sonar detection. The applicant's analysis suggests that the high noise level generated by the interaction of sound-absorbing materials with complex flow fields, or by the vibration response of the sound-absorbing materials themselves during actual underwater motion, increases the radiated noise of the vessel, negatively impacting overall acoustic stealth performance. Pulsating pressure is a noise source. Therefore, based on selecting elastic materials that meet sound absorption requirements, before applying the sound-absorbing materials to the underwater vessel, the pulsating pressure of the water at the surface of the sound-absorbing material under target operating conditions should be tested to infer the hydrodynamic excitation characteristics of the sound-absorbing material. This serves as an indicator for evaluating the performance of the sound-absorbing material, significantly improving the accuracy of material selection.

[0035] The aforementioned pulsating pressure sensor is an externally purchased product. It is a fluid dynamics pulsating pressure sensor, in which the pressure changes over time during measurement. The pulsating pressure value referred to is the total sound pressure level calculated using the OASPNL formula.

[0036]

[0037] in, The pressure is the pulsating pressure at a frequency of i Hz, expressed in Pa, and N is the upper limit of the frequency.

[0038] The circulating water tank 1 can be a water tunnel, a high-speed cavitation water cylinder, or an ordinary water pool, as long as it can ensure that the water flowing over the test surface is in a stable random state. The flow direction of the water in the circulating water tank 1 is as follows: Figure 1 , Figure 3 , Figure 5 As shown by the arrow in the image.

[0039] When the first pulsating pressure sensor 3 is installed on the plate-shaped sample 2, the first pulsating pressure sensor 3 passes through the plate-shaped sample 2, the test end of the first pulsating pressure sensor 3 faces the inside of the circulating water tank 1 and is flush with the inner wall of the circulating water tank 1, and the wiring terminal of the first pulsating pressure sensor 3 is located outside the circulating water tank 1 and is connected to the test system through a signal line; the test end of the second pulsating pressure sensor 5 faces the inside of the circulating water tank 1 and is flush with the inner wall of the circulating water tank 1, and the wiring terminal of the second pulsating pressure sensor 5 is located outside the circulating water tank 1 and is connected to the test system through a signal line.

[0040] The sidewalls of the circulating water tank 1 include a top wall, vertical sidewalls, and a bottom wall. Multiple sidewalls are provided with installation windows 11. When the plate-shaped body 44 is fixedly installed on the sidewall of the circulating water tank 1, the plate-shaped sample 2 is completely located within the installation window 11, and part of the plate-shaped body 44 is located within the installation window 11. Simultaneously, when the plate-shaped body 44 is fixedly connected to the circulating water tank 1, the plate-shaped sample 2 and part of the plate-shaped body 44 located within the installation window 11 fill the installation window 11. The first test surface 20 and the second test surface 40 serve as the wall surface of the circulating water tank 1 at the installation window 11. Figure 1 As shown.

[0041] Since the fluid flowing through the top wall of the circulating water tank 1 may contain air bubbles, affecting the accuracy of the sensor's measurement values, it is preferable that the plate-shaped body 44 is fixedly installed on the vertical side wall or bottom wall of the circulating water tank 1. When the plate-shaped body 44 is fixedly installed on the vertical side wall of the circulating water tank 1, it simulates the state of the sound-absorbing material located on the port and starboard sides of the aircraft. When the plate-shaped body 44 is fixedly installed on the bottom wall of the circulating water tank 1, the first test surface 20 and the second test surface 40 are horizontal planes, simulating the state of the sound-absorbing material located on the top of the aircraft.

[0042] One specific testing process is as follows: Step 1: Prepare the material to be tested: Select an elastic material that meets the sound absorption performance and make a plate-shaped sample 2. One side of the plate-shaped sample 2 is the first test surface 20. The plate-shaped sample 2 is provided with a first sensor mounting hole 21 that penetrates the first test surface 20. Step 2: Assemble the material to be tested: Assemble the plate-shaped sample 2 onto the rigid sample 4. The rigid sample 4 includes a plate-shaped body 44, which has a groove 42. A second test surface 40 is provided on one side of the plate-shaped body 44 with the groove 42. When the plate-shaped sample 2 is assembled onto the rigid sample 4, the plate-shaped sample 2 is sealed to the groove 42. The first test surface 20 is flush with the second test surface 40. The plate-shaped body 44 has a second sensor mounting hole 41 that penetrates the second test surface 40. Step 3: Install the sensors: Install the first pulsating pressure sensor 3 in the first sensor mounting hole 21, and install the second pulsating pressure sensor 5 in the second sensor mounting hole 41. Step 4: Place the material to be tested in the test environment: Fix the plate-shaped body 44 to the side wall of the circulating water tank 1, and make the second test surface 40 flush with the inner wall of the circulating water tank 1. The first sensor mounting hole 21 is located downstream of the second sensor mounting hole 41. Step 5, Performance Test: The water in the circulating water tank 1 is made to flow at a predetermined flow rate and a predetermined pressure. The first pulsating pressure sensor 3 detects the pulsating pressure of the water located at the first test surface 20, and the pulsating pressure value is T. The second pulsating pressure sensor 5 detects the pulsating pressure of the water located at the second test surface 40, and the pulsating pressure value is G1.

[0043] In the performance test results, if T is less than or equal to G1, the sound-absorbing material meets the requirements; if T is greater than G1, the sound-absorbing material does not meet the requirements.

[0044] Once it is determined that the sound absorption performance of the sound-absorbing material meets the requirements, a plate-shaped sample 2 is made using the sound-absorbing material. The plate-shaped sample 2 and the rigid sample 4 are then assembled and placed in a circulating water tank 1. The pulsating pressure of the water at different material properties is measured, and the hydrodynamic noise performance of the sound-absorbing material is compared and evaluated. This further narrows down the selection range of sound-absorbing materials, avoids the increase in the self-noise of the aircraft after the application of sound-absorbing materials, and allows for a more comprehensive test and evaluation of the performance of the sound-absorbing materials.

[0045] Specifically, the number of the first sensor mounting holes 21 is greater than or equal to two, such as... Figure 6 As shown, there are three first sensor mounting holes 21. The multiple first sensor mounting holes 21 are arranged in a straight line along the flow direction of water in the circulating water tank 1.

[0046] The pulsating pressure of the water at multiple test points on the first test surface 20 is measured, and the average value is taken to ensure the reliability of the test data. The multiple first sensor mounting holes 21 are arranged in a straight line along the water flow direction in the circulating water tank 1, which reduces the requirements for the cross-sectional size of the circulating water tank 1 and reduces the test cost.

[0047] After the pressure sensors are installed, the second pulsating pressure sensor 5, the first pulsating pressure sensor 3, and the third pulsating pressure sensor 8 are arranged in a straight line.

[0048] Example 2: Based on Example 1, the performance testing method for sound-absorbing materials used in underwater vehicles in this example includes, for example... Figure 6 As shown, the plate-shaped body 44 is provided with a third sensor mounting hole 45 that penetrates the second test surface 40. The third sensor mounting hole 45 is used to install the third pulsating pressure sensor 8. When installing the sensor, install the third pulsating pressure sensor 8 at the third sensor mounting hole 45; When the material to be tested is placed in the test environment, the third sensor mounting hole 45 is located downstream of the first sensor mounting hole 21, that is, the third pulsating pressure sensor 8 is located downstream of the first sensor mounting hole 21. When the water in the circulating water tank 1 flows at a predetermined flow rate and a predetermined pressure, the third pulsating pressure sensor 8 detects the pulsating pressure of the water at the second test surface 40, and the pulsating pressure value is G2.

[0049] Specifically, the test end of the third pulsating pressure sensor 8 faces into the circulating water tank 1 and is flush with the inner wall of the circulating water tank 1. The wiring end of the third pulsating pressure sensor 8 is located outside the circulating water tank 1 and is connected to the test system via a signal line. The second test surface 40 consists of two locations, one on each side of the plate-shaped sample 2 and the other on the other side of the groove 42, respectively, along the water flow direction in the circulating water tank 1. Figure 6 As shown.

[0050] A specific testing process is as follows: Step 1: Prepare the material to be tested: Select an elastic material that meets the sound absorption performance and make a plate-shaped sample 2. One side of the plate-shaped sample 2 is the first test surface 20. The plate-shaped sample 2 is provided with a first sensor mounting hole 21 that penetrates the first test surface 20. Step 2: Assemble the material to be tested: Assemble the plate-shaped sample 2 onto the rigid sample 4. The rigid sample 4 includes a plate-shaped body 44, which has a groove 42. The plate-shaped body 44 on the side of the groove 42 has a second test surface 40. The second test surface 40 consists of two locations on both sides of the groove 42 along the water flow direction in the circulating water tank 1. When the plate-shaped sample 2 is assembled onto the rigid sample 4, the plate-shaped sample 2 is sealed to the groove 42. The first test surface 20 is flush with the second test surface 40. The plate-shaped body 44 has a second sensor mounting hole 41 and a third sensor mounting hole 45 that penetrate the second test surface 40. Step 3: Install the sensors: Install the first pulse pressure sensor 3 in the first sensor mounting hole 21, install the second pulse pressure sensor 5 in the second sensor mounting hole 41, and install the third pulse pressure sensor 8 in the third sensor mounting hole 45. Step 4: Place the material to be tested in the test environment: Fix the plate-shaped body 44 to the side wall of the circulating water tank 1, and make the second test surface 40 flush with the inner wall of the circulating water tank 1. The first sensor mounting hole 21 is located downstream of the second sensor mounting hole 41, and the third sensor mounting hole 45 is located downstream of the first sensor mounting hole 21. At this time, the first pulsating pressure sensor 3 is located downstream of the second sensor mounting hole 41, and the third pulsating pressure sensor 8 is located downstream of the first pulsating pressure sensor 3. Step 5, Performance Test: The water in the circulating water tank 1 is circulated at a predetermined flow rate and pressure. The pulsating pressure values ​​simultaneously output by three pulsating pressure sensors positioned along the water flow direction in the circulating water tank 1 are as follows: The second pulsating pressure sensor 5 detects a pulsating pressure value of G1. The pulsating pressure value detected by the first pulsating pressure sensor 3 is T. The third pulsating pressure sensor 8 detects a pulsating pressure value of G2; If T is less than or equal to G1, then the sound-absorbing material meets the requirements. If T is greater than G1, then the sound-absorbing material does not meet the requirements. If T is less than or equal to G1 and G2 is less than T, the noise reduction performance of the sound-absorbing material can be extended downstream. This type of sound-absorbing material has better performance. When designing the layout of the sound-absorbing material, sound-absorbing materials with T less than or equal to G1 and G2 less than T can be used upstream of local locations of the aircraft carrier where sound-absorbing materials cannot be laid (such as observation windows) to ensure that the self-noise of the aircraft carrier is minimized. Alternatively, sound-absorbing materials can be left unlaid in local areas of the aircraft carrier to optimize the layout design of the sound-absorbing materials.

[0051] Pulsating pressure sensors are installed on both the upstream and downstream rigid samples 4 of the plate-shaped sample 2 made of sound-absorbing material. Two comparative tests are formed on the rigid sample 4, which can simultaneously test whether the sound-absorbing material will extend the suppression effect of pressure pulsation to the downstream structure. This makes it easier to select the sound-absorbing material with the best performance and optimize the layout design of the sound-absorbing material of the aircraft. The assembly structure of the rigid sample 4 and the plate-shaped sample 2 is simple and easy to install the sensors.

[0052] Example 3: Based on Examples 1 and 2, in the performance testing method for sound-absorbing materials for underwater vehicles in this embodiment, when installing the sensor, such as... Figure 5 , Figure 7 , Figure 8 As shown, a tubular sensor adapter 6 is threaded into the first sensor mounting hole 21, the second sensor mounting hole 41, and the third sensor mounting hole 45. The sensor adapter 6 inside the first sensor mounting hole 21 is threaded to the first pulsating pressure sensor 3. The second pulsating pressure sensor 5 is threaded into the inner hole of the sensor adapter 6 inside the second sensor mounting hole 41. The inner hole of the sensor adapter 6 in the third sensor mounting hole 45 is threaded to connect to the third pulsating pressure sensor 8.

[0053] The ends of all the sensor adapters 6 located inside the circulating water tank 1 are flush with the ends of the pulsating pressure sensors, and are also flush with the first test surface 20 and the second test surface 40.

[0054] Specifically, to facilitate the installation of sensor adapter 6, such as Figure 8As shown, the sensor adapter 6 in this embodiment includes a tubular body 60. The central hole of the tubular body 60 is threadedly connected to the pulsating pressure sensor. The outer circumferential surface of one axial end of the tubular body 60 facing the circulating water tank 1 is a threaded surface 61, used for threaded connection with the sensor mounting hole. The other axial end of the tubular body 60 facing the outside of the circulating water tank 1 is provided with a fastening connector 62. The fastening connector 62 can be a hexagonal columnar structure for matching fastening tools, or a socket matching fastening tools can be provided at the end of the inner hole of the tubular body 60 to facilitate the installation of the sensor adapter 6. In order to meet the universality of the sensor adapter 6, the axial dimension of the sensor adapter 6 is usually small. Therefore, in order to avoid the sensor adapter 6, the axial cross-section of the first sensor mounting hole 21, the second sensor mounting hole 41, and the third sensor mounting hole 45 is T-shaped, such as... Figure 5 As shown, a space is formed to avoid the fastening joint 62; the sensor adapter 6 is made of steel.

[0055] The sensor adapter 6 is used to indirectly connect the pulsating pressure sensor to the plate-shaped sample 2 or the rigid sample 4 via a threaded connection. The connection of the three types of components greatly reduces the probability of resonance caused by mechanical vibration, improves the accuracy of pulsating pressure testing, and reduces design difficulty. In addition, compared with the first pulsating pressure sensor 3 being directly threaded to the first sensor mounting hole 21, the sensor adapter 6 increases the thread depth of the connection with the first sensor mounting hole 21, thereby improving the strength of the mounting structure of the first pulsating pressure sensor 3.

[0056] To accurately compare the pulsating pressure values ​​output simultaneously by the three pulsating pressure sensors, the first sensor mounting hole 21, the second sensor mounting hole 41, and the third sensor mounting hole 45 have the same structural dimensions, all sensor adapters 6 have the same structural dimensions, and the first pulsating pressure sensor 3, the second pulsating pressure sensor 5, and the third pulsating pressure sensor 8 have the same model, such as Kisler 601D, to ensure the consistency of test accuracy and sensor installation accuracy.

[0057] Example 4: Based on the above embodiments, in the performance testing method for sound-absorbing materials for underwater vehicles in this embodiment, the plate-shaped body 44 is provided with a first clearance hole 71 corresponding to the first sensor mounting hole 21, and the diameter of the first clearance hole 71 is [missing information]. ,

[0058] in, Where E is the mounting diameter of the first pulsating pressure sensor 3, and E is the elastic modulus of the elastic material. The density of the elastic material, For elastic materials, Poisson's ratio The thickness of plate-shaped sample 2 The lowest frequency among the frequencies of interest in the experiment. The maximum allowable deflection for plate-shaped sample 2. The pressure is the force applied to the plate-shaped sample 2.

[0059] The mounting diameter of the first pulsating pressure sensor 3 is Specifically, if the first pulsating pressure sensor 3 is directly mounted on the first sensor mounting hole 21, then This refers to the maximum diameter of the first pulsating pressure sensor 3. If the first pulsating pressure sensor 3 is mounted on the first sensor mounting hole 21 via the sensor adapter 6, then... It is the maximum diameter of sensor adapter 6.

[0060] First and foremost, it must be ensured that the first pulsating pressure sensor 3 can pass through the first clearance hole 71; when the axial cross-section of the first sensor mounting hole 21, the second sensor mounting hole 41, and the third sensor mounting hole 45 is T-shaped, the maximum diameter of the sensor mounting hole is [missing information]. , Greater than the installation diameter ,like Figure 5 As shown.

[0061] The diameter of the aforementioned first clearance hole 71 The derivation of the expressions for the upper and lower limits of the value range is as follows: (i) If the size of the first clearance hole 71 is to have no effect on the vibration of the vibrating plate-shaped sample 2, then the diameter of the first clearance hole 71 needs to be ensured. The wavelength of the bending wave is greater than that of plate-shaped sample 2; According to the wave velocity formula for bending waves (applicable to thin plates): , and the relationship between wavelength and frequency The wavelength of the bent wave can be obtained as: , That is, the diameter of the first clearance hole 71 The lower limit for calculation.

[0062] For example, for common rubber elastic materials, the elastic modulus is... ,density Poisson's ratio The plate thickness is taken here. The frequencies we are interested in are between 10Hz and 10000Hz; here we take the lowest frequency we are interested in, which is... The frequency is 10Hz. Substituting this into the equation, we get a bending wavelength of 20mm. This means the diameter of the circular hole needs to be greater than 20mm. Additionally, the mounting diameter of the first pulsating pressure sensor 3... If the diameter is 12mm, then the diameter of the first clearance hole 71 is... The lower limit is 20mm.

[0063] For a simply supported elastic circular plate under a uniformly distributed load... Under action, the maximum deflection of the elastic plate With the diameter of the elastic plate The relationship between them can be expressed by the following formula:

[0064] It is the elastic modulus of elastic materials. It is the thickness of the elastic plate. This refers to the pressure applied to the elastic plate (in this embodiment, it is the pressure acting on the plate-shaped sample 2). To avoid the dangers of loose screws causing leaks, The thread depth of the sensor mounting diameter is taken as the maximum allowable deflection. If the first pulsating pressure sensor 3 is directly mounted on the first sensor mounting hole 21, the thread depth of the mounting diameter is the thread depth of the first pulsating pressure sensor 3. If the first pulsating pressure sensor 3 is mounted on the first sensor mounting hole 21 through the sensor adapter 6, the thread depth of the mounting diameter is the thread depth of the thread surface 61.

[0065] For example, if the thread depth of the sensor mounting diameter is 1.4mm, and the pressure on the elastic plate is calculated based on a hydrostatic pressure of 0.2m, then the diameter of the first clearance hole 71 can be obtained. The upper limit is 59.6mm.

[0066] Taking into account the performance of the elastic material and the installation requirements in the test, the upper and lower limits of the diameter of the first clearance hole 71 are reasonably set. Under the premise of meeting the installation requirements, the elastic material can maintain its elastic properties while being able to withstand pressure, so as to accurately measure the corresponding water pulsation pressure of the elastic material.

[0067] In another specific implementation, such as Figures 6-7 As shown, the plate-shaped body 44 is provided with a second clearance hole 46 corresponding to the first sensor mounting hole 21. One end of the second clearance hole 46 penetrates the bottom surface of the groove 42, and the other end of the second clearance hole 46 penetrates the side of the plate-shaped body 44 away from the groove 42. After the first pulsating pressure sensor 3 is installed on the first sensor mounting hole 21, the support base 7 is installed on the second clearance hole 46. The first clearance hole 71 is located on the support base 7 and is directly opposite the first pulsating pressure sensor 3. The support base 7 is in contact with the surface of the plate-shaped sample 2.

[0068] Specifically, the second clearance hole 46 is 100mm in size, which facilitates the insertion of a hand to install the first pulsating pressure sensor 3. Step 3, during sensor installation: With the second clearance hole 46 on the plate-shaped body 44 exposed, the first pulsating pressure sensor 3 is installed on the first sensor mounting hole 21 (specifically, the sensor adapter 6 can be installed first and then the first pulsating pressure sensor 3 can be installed on the sensor adapter 6), and the signal line of the first pulsating pressure sensor 3 is passed through the first clearance hole 71. Then, the support base 7 is fixedly connected to the second clearance hole 46, and the end face of the support base 7 along the axial direction of the second clearance hole 46 is made to contact the surface of the plate-shaped sample 2, and spliced ​​with the bottom surface of the groove 42 to form a complete plane for supporting the plate-shaped sample 2.

[0069] While ensuring that the size of the first clearance hole 71 meets the requirements, a second clearance hole 46 and a support base 7 detachably connected to the second clearance hole 46 are provided on the rigid sample 4. The first clearance hole 71 is set on the support base 7. After the first pulsating pressure sensor 3 is installed, the outer peripheral surface of the measuring part of the plate sample 2 is rigidly supported. When the size of the first clearance hole 71 is small and the thickness of the rigid sample 4 is large, the test conditions are met while improving the convenience of operation.

[0070] Specifically, such as Figure 7 As shown, the support base 7 is cylindrical. When the support base 7 is installed on the second clearance hole 46, the outer circumferential surface of the support base 7 is threadedly connected to the inner wall surface of the second clearance hole 46. The support base 7 is provided with a pair of insertion holes 72 for inserting rotating tools to facilitate operator work when installing the support base 7.

[0071] In another specific embodiment, two third clearance holes 43 are provided on the plate-shaped body 44 of the rigid sample 4. The third clearance holes 43 are blind holes that are away from the second test surface 40. The second sensor mounting hole 41 and the third sensor mounting hole 45 are respectively opposite to one of the third clearance holes 43 and penetrate through the bottom of the third clearance hole 43.

[0072] When the pulsating pressure sensor is small, the rigid sample 4 is thick, and the sensor mounting hole is too deep to operate and install, a third clearance hole 43 is provided on the plate-shaped body 44 of the rigid sample 4, which is directly opposite to the second sensor mounting hole 41 and the third sensor mounting hole 45. The diameter of the second sensor mounting hole 41 and the third sensor mounting hole 45 is much smaller than that of the third clearance hole 43, and it penetrates through the bottom of the third clearance hole 43. Specifically, the diameter of the third clearance hole 43 is 100mm.

[0073] When installing the sensor in the third step: The sensor adapter 6 is first installed in the second sensor mounting hole 41 and the third sensor mounting hole 45 by manually passing through the third clearance hole 43. Then, the second pulsating pressure sensor 5 and the third pulsating pressure sensor 8 are installed in place by manually passing through the third clearance hole 43.

[0074] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. A method for testing the performance of sound-absorbing materials for underwater vehicles, characterized in that: Includes the following steps: Select an elastic material that meets the sound absorption performance and make a plate-shaped sample (2). One side of the plate-shaped sample (2) is the first test surface (20). The plate-shaped sample (2) is provided with a first sensor mounting hole (21) that penetrates the first test surface (20). The plate-shaped sample (2) is assembled onto the rigid sample (4). The rigid sample (4) includes a plate-shaped body (44). The plate-shaped body (44) has a groove (42). The plate-shaped body (44) on the side of the groove (42) has a second test surface (40). When the plate-shaped sample (2) is assembled onto the rigid sample (4), the plate-shaped sample (2) is sealed to the groove (42). The first test surface (20) is flush with the second test surface (40). The plate-shaped body (44) has a second sensor mounting hole (41) that penetrates the second test surface (40). A first pulsating pressure sensor (3) is installed in the first sensor mounting hole (21), and a second pulsating pressure sensor (5) is installed in the second sensor mounting hole (41). The plate-shaped body (44) is fixedly installed on the side wall of the circulating water tank (1), and the second test surface (40) is flush with the inner wall of the circulating water tank (1). The first sensor mounting hole (21) is located downstream of the second sensor mounting hole (41). The water in the circulating water tank (1) is made to flow at a predetermined flow rate and a predetermined pressure. The first pulsating pressure sensor (3) detects the pulsating pressure of the water located at the first test surface (20), and the pulsating pressure value is T. The second pulsating pressure sensor (5) detects the pulsating pressure of the water located at the second test surface (40), and the pulsating pressure value is G1.

2. The performance testing method for sound-absorbing materials used in underwater vehicles as described in claim 1, characterized in that: The plate-shaped body (44) is provided with a third sensor mounting hole (45) that penetrates the second test surface (40). The third sensor mounting hole (45) is located downstream of the first sensor mounting hole (21). The third sensor mounting hole (45) is used to install a third pulsating pressure sensor (8). When the water in the circulating water tank (1) flows at a predetermined flow rate and a predetermined pressure, the third pulsating pressure sensor (8) detects the pulsating pressure of the water at the second test surface (40). The pulsating pressure value is G2.

3. The performance testing method for sound-absorbing materials used in underwater vehicles as described in claim 2, characterized in that: A tubular sensor adapter (6) is threaded into the first sensor mounting hole (21), the second sensor mounting hole (41), and the third sensor mounting hole (45). The inner hole of the sensor adapter (6) in the first sensor mounting hole (21) is threaded to the first pulsating pressure sensor (3). The inner hole of the sensor adapter (6) in the second sensor mounting hole (41) is threaded to the second pulsating pressure sensor (5). The inner hole of the sensor adapter (6) in the third sensor mounting hole (45) is threaded to the third pulsating pressure sensor (8).

4. The performance testing method for sound-absorbing materials used in underwater vehicles as described in claim 3, characterized in that: The sensor adapter (6) includes a tubular body (60), with one axial end of the tubular body (60) facing the circulating water tank (1) having a threaded surface (61), and the other axial end of the tubular body (60) facing the circulating water tank (1) having a fastening joint (62).

5. The performance testing method for sound-absorbing materials used in underwater vehicles as described in claim 1, characterized in that: The plate-shaped body (44) is provided with a first clearance hole (71) corresponding to the first sensor mounting hole (21), and the diameter of the first clearance hole (71) is [missing information]. , in, Where E is the mounting diameter of the first pulsating pressure sensor (3), and E is the elastic modulus of the elastic material. The density of the elastic material, For elastic materials, Poisson's ratio The thickness of the plate-shaped sample (2) is... The lowest frequency among the frequencies of interest in the experiment. The maximum allowable deflection of the plate-shaped sample (2) is... The pressure is the pressure acting on the plate-shaped sample (2).

6. The performance testing method for sound-absorbing materials used in underwater vehicles as described in claim 5, characterized in that: The plate-shaped body (44) is provided with a second clearance hole (46) corresponding to the first sensor mounting hole (21). One end of the second clearance hole (46) penetrates the bottom surface of the groove (42), and the other end of the second clearance hole (46) penetrates the side of the plate-shaped body (44) away from the groove (42). After the first pulsating pressure sensor (3) is installed on the first sensor mounting hole (21), the support base (7) is installed on the second clearance hole (46). The first clearance hole (71) is located on the support base (7) and is directly opposite to the first pulsating pressure sensor (3). The support base (7) is in contact with the plate-shaped sample (2).

7. The performance testing method for sound-absorbing materials used in underwater vehicles as described in claim 6, characterized in that: The support base (7) is cylindrical. When the support base (7) is installed on the second clearance hole (46), the outer peripheral surface of the support base (7) is threadedly connected to the inner wall surface of the second clearance hole (46).

8. The performance testing method for sound-absorbing materials used in underwater vehicles as described in claim 5, characterized in that: A third clearance hole (43) is provided on the plate-shaped body (44) of the rigid sample (4). The third clearance hole (43) is a blind hole that is away from the second test surface (40). The second sensor mounting hole (41) is directly opposite to a third clearance hole (43) and penetrates the bottom of the third clearance hole (43).

9. The performance testing method for sound-absorbing materials used in underwater vehicles as described in claim 1, characterized in that: The number of the first sensor mounting holes (21) is greater than or equal to two.

10. The performance testing method for sound-absorbing materials used in underwater vehicles as described in claim 7, characterized in that: The multiple first sensor mounting holes (21) are arranged in a straight line along the flow direction of water in the circulating water tank (1).

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