A test system for flow-induced sound vibration of aircraft surface structure gaps and seals

Abstract

A kind of test system of aircraft surface structure gap and seal piece flow-induced sound vibration, wherein the test system is substantially a longitudinally extending multi-pipe segment closed structure, the multi-pipe segment closed structure is mounted on a support, and includes gas supply section, noise elimination and flow stabilizing and pressure stabilizing section, test section and gas release section connected in sequence;Wherein the test section includes sample mounting part, the test sample container of the sample mounting part is detachably connected, the pressure and temperature in the test sample container are controlled;The test section further includes microphone and vibration meter.The system can simulate aircraft cruising speed flow field and can simulate temperature and pressure difference environment when aircraft is running, obtain flow-induced noise spectrum, flow-induced vibration spectrum and transfer characteristics of typical structure gap and seal piece in simulated aircraft working environment, and key data in the field of civil aircraft vibration reduction and noise reduction control technology.

Description

Technical Field

[0001] This invention relates to the field of aircraft manufacturing, and in particular to a testing system for flow-induced acoustic vibrations in aircraft surface structure gaps and seals. Background Technology

[0002] During flight, such as when a civil aircraft accelerates from a low ground speed to cruising speed (e.g., within the Mach 0.8 to Mach 0.9 range), the high-speed airflow over the aircraft's surface often creates self-sustaining oscillations as it passes through gaps in the surface structure or seals. This generates severe noise and structural vibration, affecting cabin comfort and potentially causing structural damage. Furthermore, due to the widespread presence and complex structure of gaps in the aircraft's surface structure and seals, the detection of such flow-induced acoustic vibration problems often relies on testing methods. Existing testing methods often employ wind tunnel testing, but this falls short of the necessary acoustic and vibration measurements and cannot simulate the temperature and pressure environment that significantly impacts rubber seals during aircraft operation. Therefore, current technologies have limitations in testing flow-induced acoustic vibration in aircraft surface structure gaps and seals.

[0003] Specifically, the main purpose of commonly used wind tunnel testing systems is to test the characteristics of the flow field itself and study the pressure changes in the flow field caused by airflow, without collecting sound and vibration signals, thus making it impossible to conduct flow-induced acoustic vibration testing. Although a few existing acoustic wind tunnel testing systems can achieve flow-induced sound field testing, the following problems still exist: 1. Acoustic wind tunnels are usually located in anechoic chambers, and their large size results in low flow field velocities, typically around Mach 0.3, far lower than the cruising speed of civil aircraft; 2. Their test objects are simple rigid structures, making it impossible to conduct acoustic testing of flexible structures such as seals under flow field excitation; 3. Acoustic wind tunnels only collect flow field and sound field signals, making it impossible to conduct flow-induced vibration testing; 4. They lack temperature and pressure difference control systems, making it impossible to conduct flow-induced acoustic vibration testing of seals (rubber-fabric products) under the influence of high and low temperatures and pressure differences, i.e., unable to simulate the real aircraft cruising environment.

[0004] Furthermore, testing of aircraft seals primarily focuses on the seal's mechanical properties, fire resistance, and leakage under differential pressure. Traditional testing systems in this area cannot perform flow-induced acoustic vibration testing. Moreover, the mechanical properties of civil aircraft seals, which are mainly composed of rubber, are highly sensitive to temperature. The typical operating temperature range for civil aircraft is ±60°C, making temperature a crucial control variable in the testing system. Additionally, because civil aircraft operate under pressurization during cruise, the pressure difference between the cabin and the outside can reach 8 PSI. The seals are subjected to this pressure load, resulting in significant variations in their acoustic vibration performance. Therefore, existing civil aviation seal testing technologies are also unable to perform flow-induced acoustic vibration testing.

[0005] Existing technology CN110287643A relates to a wind tunnel simulation method for the coupling characteristics of flow-induced vibration and flow-induced noise in cavities. It uses equation analysis to establish the governing equations and boundary conditions for the coupling characteristics of flow-induced vibration and flow-induced noise in cavities, transforming dimensional physical parameters into a similarity criterion dataset of dimensionless physical parameters. Based on this similarity criterion dataset, it designs wind tunnel experimental models, selects incoming flow conditions, and corrects wind tunnel experimental results. However, this existing technology addresses the problem of the coupling characteristics of flow-induced vibration and flow-induced noise in cavities, not the problem of testing flow-induced acoustic vibration caused by gaps and seals in aircraft surface structures. Furthermore, while it establishes a similarity criterion dataset by setting up governing equations and boundary conditions for the coupling characteristics of flow-induced vibration and flow-induced noise in cavities and modifies wind tunnel data, it does not solve the problem of testing flow-induced acoustic vibration caused by gaps and seals in the fuselage structure and changes in the flight environment, which is the focus of this invention.

[0006] Prior art US14069691 relates to a flow-induced noise source identification method for automatically detecting and tracking temporal and spatial changes in flow structures to locate and characterize the flow structures that generate noise, and quantifying the acoustic radiation characteristics of the response. However, this prior art addresses the problem of flow-induced noise source identification in flow field acoustic simulation. It identifies and tracks eddies by analyzing flow field data, obtaining parameters such as the position, length, and radius of the eddies in multiple time steps to simulate the noise generated by the eddies. However, it does not address the testing of flow-induced acoustic vibrations caused by changes in the flight environment of aircraft fuselage structures and seals, which is the focus of this invention.

[0007] Therefore, it can be understood that both traditional high-speed and low-speed wind tunnels are mainly used to measure the pulsating pressure on the surface of a structure under airflow excitation. Consequently, the (flow-induced) noise of these systems is very high, making them unsuitable for acoustic measurements. To address this issue, acoustic wind tunnels have been designed, which involve noise reduction treatment of the wind tunnel system to meet acoustic measurement requirements. These acoustic wind tunnels can meet acoustic measurement needs, but they are generally large in size and have extremely high construction and testing costs.

[0008] In view of the above-mentioned situation of the existing technology, there is an urgent need to provide a test system for flow-induced acoustic vibration of structural gaps and seals on aircraft surfaces. This system can simulate the flow field at the cruising speed of an aircraft, test the acoustic vibration characteristics of typical structural gaps and seals under flow field excitation, and simulate the temperature and pressure difference environment of the aircraft during operation near the test pieces such as typical structural gaps and seals on the aircraft surface. It can obtain key data in the field of vibration reduction and noise control technology of civil aircraft, such as the flow-induced noise spectrum, flow-induced vibration spectrum and transmission characteristics of typical structural gaps and seals simulating the aircraft working environment. Summary of the Invention

[0009] In view of the above-mentioned situation of the prior art, the purpose of the present invention is to provide a test system for flow-induced acoustic vibration of aircraft surface structural gaps and seals. The system can simulate the flow field at the aircraft's cruise speed and test the acoustic vibration characteristics of typical structural gaps and seals under flow field excitation.

[0010] Furthermore, the present invention aims to simulate the temperature and pressure difference environment of an aircraft during operation near test pieces such as typical structural gaps and seals on the aircraft surface, and obtain key data in the field of vibration reduction and noise control technology for civil aircraft, such as the flow-induced noise spectrum, flow-induced vibration spectrum and transmission characteristics of typical structural gaps and seals simulating the aircraft working environment.

[0011] Furthermore, the present invention aims to provide a small-size, low-cost system that can perform high subsonic flow-induced noise testing, a function that other systems do not possess.

[0012] Furthermore, the present invention aims to address the different acoustic vibration characteristics of rubber due to varying material properties at different temperatures. A temperature control system for the test sample (rubber-based) and a pressure control system are added to the testing system to better simulate the real working environment of rubber. To achieve the above technical effects, the present invention provides a testing system for flow-induced acoustic vibration of aircraft surface structural gaps and seals. The testing system is generally a longitudinally extending multi-segment closed structure mounted on a support, and includes a gas supply section, a noise reduction and flow / pressure stabilization section, a testing section, and a gas release section connected sequentially. The testing section includes a sample mounting part, to which a test sample container is detachably connected. The pressure and temperature inside the test sample container are controlled. The testing section also includes a microphone and a vibration meter.

[0013] Preferably, the noise reduction and voltage stabilization section includes a first noise reduction and voltage stabilization section and a second noise reduction and voltage stabilization section, which are respectively connected to the upstream and downstream sides of the test section.

[0014] Preferably, it also includes an expansion section connected between the upstream of the gas release section and the downstream of the test section.

[0015] Preferably, it also includes a flow rate control section, which includes at least one flow control valve connected to the outlet pipe of the gas supply section.

[0016] Preferably, the gas supply section includes a gas storage tank, which is a high-temperature and high-pressure air storage tank.

[0017] Preferably, a flow rate control valve is provided on the outlet pipeline of the gas storage tank.

[0018] Preferably, the noise reduction and pressure stabilization section includes a pipe section shell, and the pipe section shell is provided with a honeycomb rectification structure.

[0019] Preferably, a microphone is installed at an appropriate location on the pipe section housing of the noise-absorbing and pressure-stabilizing flow section to measure sound pressure, and a flow meter or flow probe is also provided on the pipe section housing of the noise-absorbing and pressure-stabilizing flow section at a location corresponding to the microphone or at another appropriate location.

[0020] Preferably, the test section includes a pipe housing, and a microphone hole is provided on the side wall of the housing for the microphone to be installed therein in a sealed manner.

[0021] Preferably, the microphone holes are arranged in an array.

[0022] Preferably, the transverse cross-section of the pipe section shell is square, rectangular, or circular.

[0023] Preferably, the sample mounting portion of the test section is an opening on the side wall of the pipe section shell, having a stepped engagement structure for detachably engaging with the sample container.

[0024] Preferably, at least one of the sidewalls of the test section housing that does not include the sample mounting portion is transparent, so that the laser of the non-contact laser vibrometer can penetrate the sidewall to perform vibration testing on the test sample.

[0025] Preferably, the test sample container includes an edge portion for cooperating with the test sample mounting portion and a container body, the container body for accommodating the test sample and forming a temperature and pressure control zone within the container body so that the temperature and pressure therein are controlled to have a temperature difference and pressure difference with the flow field within the pipe section shell of the test section.

[0026] Preferably, the test sample container is provided with a gas inlet, through which an external gas pump supplies gas to the temperature and pressure control zone to achieve the required gas pressure, thereby creating a stable pressure difference at the interface between the test sample at the sample mounting part of the test section and the flow field inside the pipe shell of the test section.

[0027] Preferably, the inner wall of the sample container is provided with a heating wire and a circulating cooling system at an appropriate position to heat the gas in the temperature and pressure control zone to obtain the required temperature, or to inject the gas required for the test into the sample container so as to form a stable temperature field at the interface between the test sample at the sample mounting part of the test section and the flow field inside the pipe shell of the test section.

[0028] Preferably, the expansion section includes a tube housing that is generally funnel-shaped to cause the airflow pressure from the test section to drop rapidly.

[0029] Preferably, the gas release section includes a vacuum tank; the inner end of the vacuum tank is also equipped with a sound-absorbing wedge that can operate normally under vacuum negative pressure, high pressure and airflow impact to suppress the sound pressure of the gas release section and the overall test system.

[0030] Preferably, the support consists of a bracket assembly composed of multiple brackets and a track. The bracket assembly is slidably mounted on the track, and the multi-segment enclosed structure is supported by the bracket assembly, thereby allowing it to slide on the track.

[0031] Preferably, vibration dampers are also provided on the bracket assembly and the track.

[0032] Preferably, the test section may include one or more sample mounting parts, each sample mounting part being detachably connected to a corresponding number of test sample containers for testing one or more test samples. Attached Figure Description

[0033] Figure 1 This is a perspective view of an embodiment of a test system for testing aircraft surface structure gaps and flow-induced acoustic vibrations of seals according to the present invention;

[0034] Figure 2 This is the present invention. Figure 1 A partial schematic diagram of the noise reduction and current / voltage stabilization sections in the test system shown, in which part of the housing has been removed to reflect its internal structure;

[0035] Figure 3 It is perpendicular to Figure 1 Paper orientation relative to the present invention Figure 1 A partial schematic diagram of the test section in the test system shown, in which the test sample has been installed;

[0036] Figure 4 It is parallel to Figure 1 Viewing the invention from the paper orientation Figure 1 A top view of the test section in the test system shown, which schematically illustrates the flow field state within the test section shell;

[0037] Figure 5 yes Figure 3 A partial schematic diagram of the test section is shown, illustrating another embodiment of the test sample container; and

[0038] Figure 6 It is parallel to Figure 1 Paper orientation relative to the present invention Figure 1 A partial schematic diagram of the expansion section and vacuum tank section in the test system shown. Detailed Implementation

[0039] like Figure 1 As shown in the figure, an embodiment of a test system for testing flow-induced acoustic vibrations of aircraft surface structure gaps and seals according to the present invention is illustrated. The test system of the present invention is generally a longitudinally extending tubular structure. For clarity of explanation of the structure of the test system of the present invention, it is referred to herein as... Figure 1 The left and right directions of the image are vertical, the left and right sides perpendicular to it are horizontal, and the up and down directions perpendicular to it are vertical.

[0040] This invention provides a testing system for flow-induced acoustic vibration of aircraft surface structural gaps and seals. The testing system is generally a longitudinally extending multi-segment closed structure mounted on a bracket and includes a gas supply section, a noise reduction and flow / pressure stabilization section, a testing section, and a gas release section. The testing section includes a sample mounting part, to which a test sample container is detachably connected. The pressure and temperature within the test sample container are controlled. The testing section also includes a microphone and a vibration meter. The following description, in conjunction with specific embodiments, illustrates the solution of this invention.

[0041] In this embodiment, the multi-segment closed structure, running longitudinally from right to left, may include a gas storage segment 1 (serving as a gas supply segment), a flow rate control segment 2, a first noise reduction and flow / pressure stabilization segment 3, a testing segment 4, a second noise reduction and flow / pressure stabilization segment 5, an expansion segment 6, and a vacuum tank 7 (serving as a gas release segment), etc. These segments can be placed on a support 8 of the testing system. The following detailed description, in conjunction with the accompanying drawings, will provide a clearer understanding of the function and effect of each component:

[0042] The test system embodiment of the present invention includes a gas supply section 1, which is used to generate and store high-pressure gas for testing. This gas supply section can be, for example, a gas storage tank 11, which can be small and placed in a typical test room. To control the gas supply to the gas storage tank 11, a control valve (not shown in the figure) can be installed on the outlet pipe 12 of the gas storage tank 11. Preferably, since the compressed air in the gas storage tank 11 causes the air temperature to rise, the actual high-temperature, high-pressure gas flowing in the outlet pipe of the gas storage tank can reach a temperature as high as 180°C. Therefore, a high-speed, high-pressure solenoid valve suitable for temperatures of approximately 180°C can be used. Furthermore, a safety detection system can be installed inside the gas storage tank 11 to detect the internal pressure. Because the gas storage tank 11 is a pressure vessel, for safety reasons, the pressure difference between the detected pressure inside the gas storage tank 11 and atmospheric pressure must not exceed a safe range. This range is determined by the characteristics of the gas storage tank 11 itself; exceeding this range may cause safety problems. Therefore, an automatic pressure relief system (not shown in the figure) can be configured to automatically or manually release pressure when the pressure inside the gas tank reaches the warning value, ensuring the safety of the testing system. Of course, checking whether the pressure inside the gas tank exceeds the safe range is performed before the test begins. Once the test begins, gas tank 1 is generally in a depressurized state, and the possibility of exceeding the pressure warning value is low.

[0043] The test system embodiment of the present invention preferably includes a flow rate control section 2, which includes one or more flow control valves, such as pneumatic or electromagnetic control valves (not shown in the figure), to control the gas flow rate in the test system to meet experimental requirements by opening or closing one or more control valves. These control valves are connected after the outlet pipe 12 of the gas storage section 1 to control the flow of high-pressure gas from the outlet to the next section at a certain flow rate. Typically, the function of the flow rate control section 2 is to control the flow rate at a rate slightly higher than the test requirement, because there will be some flow rate loss when the airflow passes through the subsequent silenced flow stabilization and pressure stabilization section 3. In other words, the actual air flow rate in the test system of the present invention is determined based on the flow rate required by the test section 4. Furthermore, it will be understood by those skilled in the art that this flow rate control section 2 is also optional. When the gas flow rate out of the gas storage tank 1 can be advantageously controlled due to the setting of control valves, this flow rate control section 2 can also be avoided in the test system to make the system more compact or reduce the system installation size.

[0044] The test system embodiment of the present invention includes a first noise reduction and flow / pressure stabilization section 3, which is connected to the flow rate control section 2 or directly connected to the gas storage tank 1. Its typical structure is as follows: Figure 2As shown, in this embodiment, the system includes a pipe section housing 31 and a honeycomb rectification structure 32 disposed therein. The honeycomb rectification structure 32 is composed of high-strength, high-aperture metal wire mesh layers, which optimizes the flow field of the airflow from the flow rate control section. Its purpose is to reduce the turbulence of the subsequent test section and to suppress the airflow noise in upstream and downstream sections, such as the gas storage tank 1 (excluding test section 4). Furthermore, a microphone 33 can be installed at an appropriate location on the pipe section housing 31 to measure the sound pressure at that location, thereby determining the sound pressure of the airflow upstream of test section 4. A flow meter 34 or a flow probe 35 can also be installed on the housing 31 at a location corresponding to the microphone 33 or other appropriate locations to measure the flow velocity of the test system at this stage. If the airflow velocity does not meet the test flow velocity requirements, the pneumatic control valve in the flow rate control section 2 or the control valve in the gas storage tank 1 should be adjusted so that the flow velocity measured in the first noise reduction and flow stabilization section 3 meets the flow velocity requirements for the subsequent test section 4.

[0045] Test segment 4, specifically as follows Figure 3 and Figure 4 As shown, Figure 3 It is perpendicular to Figure 1 Paper orientation relative to the present invention Figure 1 A partial schematic diagram of the test section in the test system shown, in which the test sample has been installed; Figure 4 It is parallel to Figure 1 Viewing the invention from the paper orientation Figure 1 The diagram shows a top view of the test section in the test system, which schematically illustrates the airflow conditions in the pipe section.

[0046] Specifically, test section 4 includes a pipe section shell 41, the cross-section of which can be, for example, square, circular, rectangular, etc., preferably square or rectangular to facilitate the installation of the test sample. The top wall of the pipe section shell 41 of this test section 4 ( Figure 4 (Schematic shown) or other sidewalls have holes 42, for example at least four holes, for mounting a microphone. Figure 4 The illustrated embodiment exemplifies the use of 12 microphones 43. These holes for mounting the microphones can be pre-fabricated in the housing wall, and the number should generally be sufficient to accommodate the number of microphones required for testing a large number of test samples. During testing, microphones can be installed in these holes according to the actual number required. It is important to note that after installing the microphones 43, the gaps between the microphones and the holes need to be sealed to maintain a sealed state within the pipe section. When no testing is being conducted or when there are extra holes without microphones installed, special plugs should be used to seal the holes to prevent air leakage in the system and to reduce acoustic signal measurement errors. Preferably, as shown... Figure 4As shown, the microphones 43 can be arranged in an array, such as the linear parallel array shown in the figure. However, as those skilled in the art will understand, they can also be arranged in other array configurations. The microphone aperture 42 and the microphones 43 can also be... Figure 3 As shown, it is installed on the side wall of the pipe section shell, from Figure 3 As can be seen, in the installed state, the microphone 43 is flush with the inner surface of the side wall of the pipe section shell, so that the installation does not interfere with the flow field of the pipe section shell 41.

[0047] like Figure 3 As shown, the test section 4 also has a test sample mounting part 44 on the side wall of the pipe section shell. This mounting part can be an opening on the side wall. To facilitate the connection of a test sample container 101, a stepped structure 441 as shown in the figure can be adopted. The inner wall of the pipe section shell can be polished and treated with anti-corrosion, especially the stepped structure part 441 of the mounting part 44 is preferably precision machined to facilitate high-precision engagement and assembly with the test sample container 101, achieving flush and seamless installation of the test sample container and the inner wall of the pipe section shell, simulating the actual installation state of a civil aircraft for typical configuration test samples. At the same time, as Figure 3 As shown, microphones 42 and 43 are located on the same side as the test sample mounting section 44.

[0048] In addition, such as Figure 3 and Figure 4 As shown, preferably, at least one sidewall of the pipe section housing 41 of the test section 4 that does not have a sample mounting portion should be transparent so that the laser of the non-contact laser vibrometer 102 can penetrate the sidewall for vibration testing; as shown Figure 3 The dashed line in the image represents the laser path during this non-contact vibration test.

[0049] In this embodiment, the microphone 42 in test section 4 and the microphone 33 in the first noise reduction and flow stabilization section 3 can complete the flow-induced sound field test. The microphone 33 in the noise reduction and flow stabilization section 3 is used to measure the noise of the airflow before entering test section 4 and its upstream pipeline (such as the gas storage tank 1 and the flow rate control section 2), i.e., the background noise of the test system. The microphone array composed of the microphones 42 provided on the side wall of the pipe section shell 41 of test section 4 is used to test the flow-induced noise generated by the sample under fluid excitation.

[0050] like Figure 3 and Figure 4As shown, the test sample container 101 of the test system of the present invention includes an edge portion 101A for engaging with the test sample mounting portion 44 and a container body 101B. The test sample S, such as a civil aircraft seal S, is placed inside the container body 101B. Through a locking structure that engages with the mounting portion 44, the container body 101B is connected to the mounting portion 44 of the test section 4 via the edge portion 101A. The edge portion 101A is flush with and sealed to the inner wall of the pipe section housing 41 without interfering with airflow.

[0051] Better, such as Figure 3 As shown, the test sample S is installed in the installation container 101 in a manner simulating the installation state of a civil aircraft seal. S1 is the civil aircraft cabin door seal, S2 is the civil aircraft cabin door seal stop, and S3 is the fuselage structure at the civil aircraft cabin door connection. The seal stop S2 and the fuselage structure S3, together with the inner wall of the test sample container 101, form a temperature and pressure control zone I. This control zone can achieve flow field control with the pipe section shell 41 of the test section 4 (in...). Figure 4 The temperature difference and pressure difference are shown schematically in the diagram.

[0052] like Figure 3 In the illustrated embodiment, a gas inlet 101C is also provided on the test sample container 101. An external air pump 103 supplies gas to the control zone I through the gas inlet 101C to achieve the required air pressure. A temperature and pressure probe 104 is installed at an appropriate position in the control zone I to monitor the pressure difference between the control zone I and the flow field inside the test section 4 pipe shell 41. This results in a stable pressure difference being formed at the interface between the sealed test sample S at the mounting part 44 of the test section 4 and the flow field inside the test section 4 pipe shell 41. At the same time, the temperature is also monitored to stabilize the pressure difference between the test sample and the test section interface and the temperature of the test sample within the operating range of the civil aircraft.

[0053] In this embodiment, in order to ensure that the flow field in the control section I and the housing 41 has a stable temperature field, the gas at the required temperature can be directly supplied by the external air pump 103.

[0054] like Figure 3 As shown, the accelerometer 105 is installed on the sealing baffle S2 of the test sample S. The vibration data measured by the accelerometer 105 or the laser vibration meter 102 can be used alone or in conjunction with the microphone signal to complete the measurement of acoustic vibration data such as the acoustic vibration transfer function.

[0055] Figure 5 yes Figure 3The diagram shows a partial view of the test section, illustrating another embodiment of the test sample container 101. Specifically, a heating wire and circulating cooling pipe assembly 106 is provided at an appropriate position on the inner wall of the sample container 101 to heat the gas in the temperature and pressure control zone I by raising or lowering the temperature inside the container 44, thereby obtaining the desired temperature. The temperature and pressure probe 104 monitors the pressure difference between the control zone I and the flow field inside the test section 4 pipe shell 41, thereby forming a stable temperature and pressure field at the interface between the sealed test sample S at the mounting part 44 of the test section 4 and the flow field inside the test section 4 pipe shell 41. Simultaneously, the temperature is monitored to adjust the temperature of the test sample to a specified temperature, thereby stabilizing the pressure difference and temperature of the test sample at the interface between the test sample and the test section within the operating range of the civil aircraft.

[0056] Although only one mounting section and one sample container are shown in the illustrated embodiment, a single testing system can be equipped with multiple test sample mounting sections and sample containers as needed. Furthermore, the connection structure between the mounting section and the sample container can be any detachable connection structure, such as an insertion type, in addition to the snap-fit ​​structure described above, as long as it does not easily cause flow field turbulence or generate noise that interferes with the measurement under flow field excitation.

[0057] The test system embodiment of the present invention also includes a second noise reduction and pressure stabilization section 5, which is connected between the test section 4 and the expansion section 6 and vacuum tank 7 described below. The structure of the second noise reduction and pressure stabilization section 5 is basically the same as that of the first noise reduction and pressure stabilization section 3, that is, it also includes the pipe section shell and the honeycomb rectification structure provided therein. The honeycomb rectification structure is made of high-strength, high-aperture metal wire mesh, which optimizes the flow field of the airflow from the flow rate control section. Its purpose is to reduce the turbulence of the subsequent test section, and at the same time suppress the airflow noise in the upstream and downstream pipe sections to a certain extent.

[0058] The test system embodiment of the present invention may also preferably include an expansion segment 6, such as Figure 1 and specifically as Figure 6 As shown, it is mainly used to quickly reduce the airflow outlet pressure of test section 4 and increase the flow velocity of test section 4, such as... Figure 6 As shown, it includes a pipe section housing 61, which is generally a funnel-shaped channel to rapidly reduce the airflow pressure from the test section 4 and allow it to enter the downstream vacuum tank 7.

[0059] The test system embodiment of the present invention also includes a vacuum tank 7, for example, which may serve as a gas release section. Figure 1The tank body 71 shown is preferably made of large-diameter seamless stainless steel tubing. In the event of an upstream airflow control failure or malfunction, such as during certain test failures where airflow control is compromised, the gas storage section 1 may rapidly release high-pressure gas into the entire system. This gas quickly rushes through the pipeline into the vacuum tank, potentially causing a high pressure shock to the vacuum tank in a very short time. If the vacuum tank cannot withstand the pressure, it may lead to localized damage. Therefore, the tank body 71 of the vacuum tank 7 must be able to withstand pressures of, for example, above 2 MPa. The tank body 71 can also be equipped with safety relief valves (not shown in the figure) for different pressures. Figure 6 As shown, the end of the vacuum tank is also equipped with a sound-absorbing wedge 72 that can work normally under vacuum negative pressure, high pressure and airflow impact to form a sound-absorbing end, suppress the sound pressure of the vacuum tank and the overall test system, and optimize the acoustic measurement conditions of the test section.

[0060] Test system bracket 8, such as Figure 1 As shown, the support 8 consists of a bracket assembly composed of multiple brackets 81 and a track 82. The bracket assembly is slidably mounted on the track 82, and multiple pipe sections 1-7 are supported by the bracket assembly. This allows the bracket assembly to slide along the track 82 with the pipe sections 1-7, facilitating the overall docking and installation of the testing system onto the test piece. Furthermore, vibration dampers can be installed on the track 82 and the bracket assembly. By designing the vibration damper frequency, the testing environment can be isolated from the testing system, reducing the impact of environmental vibration on the testing system and improving the stability and vibration testing accuracy of the testing system.

[0061] Based on the testing system of the present invention described above, a specific test case is described below:

[0062] The test sample was a cabin door seal from a large civil aircraft, such as... Figure 5 As shown. The test sample S consists of three parts: a rubber seal S1, a metal seal stop S2, and a metal or composite material fuselage structure S3 at the connection point.

[0063] In the experimental cases of this invention, the specific structure of the civil aircraft sealing component test piece mounting container 101 is designed according to the specific structure of the test sample, such as... Figure 3 As shown.

[0064] The test sample is externally mounted to the side wall of the pipe section shell 41 of the test section 4 via the test sample container 101, using a stepped locking structure or insertion structure as described in the above embodiments. Figure 3 , Figure 4 As shown. After the experiment begins, a high-speed airflow flows from the gas storage section 1 to the vacuum tank 7 at a given Mach number. During this process, a stable flow field is formed in the intermediate test section 4, for example, through the action of the silencing and pressure-stabilizing sections 3 and 5. Figure 4 As shown.

[0065] The complex gap formed by the test sample S is exposed to the high-speed airflow in test section 4, such as Figure 3 As shown, this generates complex acoustic and vibration signals.

[0066] A microphone array was installed in test section 4. Figure 3 (43) Acoustic signals are collected by a non-contact laser vibration meter 102 through the transparent shell wall of the test section 4 to collect the vibration signal of the seal S1. The laser path is shown as a dashed line.

[0067] Since the seal S1 is made of rubber, it is sensitive to temperature and pressure difference. In the test sample container 101, an external air pump 103 supplies gas to the temperature and pressure control zone I to achieve the aforementioned gas pressure, thereby stabilizing the pressure difference at the interface between the test sample and the flow field inside the shell. At the same time, the supplied gas can be preheated or heated by the heating wire and circulating cooling assembly 106 built into the sample container 101, thereby stabilizing the temperature field at the interface between the test sample and the flow field inside the pipe section shell.

[0068] During the experiment, when the upstream and downstream flow meters or flow probes of the system under test reach the required Mach number, such as 0.8 MACH, the temperature and pressure indicators in temperature and pressure control zone I display the readings of the differential pressure temperature probe. If the required temperature and pressure, such as -20℃ and 3 PSI, are reached, the microphones (upstream and downstream monitoring microphones 33 and microphone array 43) and laser vibrometer 102 can be activated to collect signals. After signal collection, the flow-induced noise spectrum, flow-induced vibration spectrum, and transmission characteristics can be obtained through the upstream and downstream monitoring microphones 33, microphone array 43, and laser vibrometer 102. Combined with the environmental data of the test system, such as flow velocity, temperature, and pressure, the acoustic and vibration characteristics of the hatch seal sample S in the cruise environment can be analyzed.

[0069] Compared with the prior art, the present invention has the following advantages and innovations:

[0070] This invention can be used to directly measure the acoustic and vibration characteristics of surface structural gaps and seals of civil aircraft under stable inflow excitation, and can create a temperature and pressure difference environment that simulates the working environment of an aircraft in the test piece area, thereby improving the authenticity and reliability of the measurement.

[0071] The flow field velocity can reach Mach 0.9, which meets the requirements for measuring the cruise speed of civil aircraft;

[0072] The testing system features noise reduction and vibration isolation treatments to improve the accuracy of acoustic and vibration measurements;

[0073] The test section is equipped with a microphone array, contact or non-contact vibration acquisition system, which can be used to perform acoustic and vibration tests;

[0074] The temperature of the test sample area can be adjusted between ±60°C, and a pressure difference of up to 8 PSI can be formed at the interface between the test sample and the test system to simulate the actual working environment of the test sample during the operation of a civil aircraft.

[0075] The test samples and test sections are independent, and one test system can be equipped with multiple test specimen installation sections, which is convenient for replacement and improves measurement efficiency.

[0076] Although the present invention has been described above in conjunction with the accompanying drawings and embodiments, those skilled in the art will understand that any variations or modifications made within the scope of the inventive concept, as well as equivalent substitutions for the specific features described herein, fall within the protection scope of the appended claims.

Claims

1. A testing system for flow-induced acoustic vibration of aircraft surface structural gaps and seals, characterized in that, The testing system is generally a longitudinally extending multi-segment closed structure, which is mounted on a support and includes a gas supply section, a noise reduction and pressure stabilization section, a testing section, and a gas release section connected in sequence. The testing section includes a sample mounting section, to which a test sample container is detachably connected. The pressure and temperature inside the test sample container are controlled. The testing section also includes a microphone and a vibration meter. The test sample container includes an edge portion for cooperating with the test sample mounting portion and a container body. The container body is used to contain the test sample and forms a temperature and pressure control zone in the container body so that the temperature and pressure therein are controlled, so as to have a temperature difference and pressure difference with the flow field in the pipe section shell of the test section.

2. The testing system as described in claim 1, characterized in that, The noise reduction and voltage stabilization section includes a first noise reduction and voltage stabilization section and a second noise reduction and voltage stabilization section, which are respectively connected to the upstream and downstream sides of the test section.

3. The testing system as described in claim 1, characterized in that, It also includes an expansion section, which is connected between the upstream of the gas release section and the downstream of the test section.

4. The testing system as described in claim 1, characterized in that, It also includes a flow rate control section, which is connected to the outlet pipe of the gas supply section.

5. The testing system as described in claim 1, characterized in that, The gas supply section includes a gas storage tank, which is a high-temperature and high-pressure air storage tank.

6. The testing system as described in claim 5, characterized in that, A flow rate control valve is installed on the outlet pipe of the gas storage tank.

7. The testing system as described in claim 1, characterized in that, The noise reduction and pressure stabilization section includes a pipe section shell, and the pipe section shell is provided with a honeycomb rectification structure.

8. The testing system as described in claim 7, characterized in that, A microphone is installed at an appropriate location on the pipe section shell of the noise-absorbing and pressure-stabilizing flow section to measure sound pressure. A flow meter or flow probe is also provided on the pipe section shell of the noise-absorbing and pressure-stabilizing flow section at a location corresponding to the microphone or at another appropriate location.

9. The testing system as described in claim 1, characterized in that, The test section includes a pipe housing, and a microphone hole is provided on the side wall of the pipe housing for the microphone to be installed therein in a sealed manner.

10. The testing system as described in claim 9, characterized in that, The microphone holes are arranged in an array.

11. The testing system as described in claim 9, characterized in that, The transverse cross-section of the pipe section shell is square, rectangular, or circular.

12. The testing system as described in claim 9, characterized in that, The sample mounting portion of the test section is an opening on the side wall of the pipe section shell, and has a stepped engagement structure to be detachably engaged with the sample container.

13. The testing system as described in claim 9, characterized in that, At least one of the sidewalls of the test section housing, excluding the sample mounting portion, is transparent, so that the laser of the non-contact laser vibrometer can penetrate the sidewall to perform vibration testing on the test sample.

14. The testing system as described in claim 1, characterized in that, The test sample container is provided with a gas inlet, through which an external gas pump supplies gas to the temperature and pressure control zone to achieve the required gas pressure, thereby creating a stable pressure difference at the interface between the test sample at the sample mounting part of the test section and the flow field inside the pipe shell of the test section.

15. The testing system as described in claim 11, characterized in that, The sample container is equipped with a heating wire and a circulating refrigeration system at appropriate positions on its inner wall to heat the gas in the temperature and pressure control zone to obtain the required temperature, or to inject the gas required for the test into the sample container so as to form a stable temperature field at the interface between the test sample at the sample mounting part of the test section and the flow field inside the pipe shell of the test section.

16. The testing system as described in claim 3, characterized in that, The expansion section includes a tube housing that is generally funnel-shaped to cause a rapid decrease in airflow pressure from the test section.

17. The testing system as described in claim 1, characterized in that, The gas release section includes a vacuum tank; the inner end of the vacuum tank is also equipped with a sound-absorbing wedge that can work normally under vacuum negative pressure, high pressure and airflow impact to suppress the sound pressure of the gas release section and the overall test system.

18. The testing system as described in claim 1, characterized in that, The support consists of a bracket assembly composed of multiple brackets and a track. The bracket assembly is slidably mounted on the track. The multi-segment enclosed structure is supported by the bracket assembly, so that it can slide on the track with the support of the bracket assembly.

19. The testing system as described in claim 18, characterized in that, Vibration dampers are also provided on the bracket assembly and the track.

20. The testing system as described in claim 1, characterized in that, The test section may include one or more sample mounting parts, each sample mounting part being detachably connected to a corresponding number of test sample containers for testing one or more test samples.

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