A metal bellows modal and flow-induced vibration test device

Abstract

The present invention discloses a metal bellows modal and flow-induced vibration test device, which belongs to the field of cryogenic fluid transmission technology, and includes an adjustable bellows system, a circulation pipeline system and a signal acquisition device; the circulation pipeline system includes an upstream pipeline, a downstream pipeline and a load loading mechanism; the upstream pipeline extracts liquid from a water tank, and an air compressor introduces gas into the pipeline; the adjustable bellows system in the downstream pipeline is connected to the left side of the T-shaped three-way pipe, and the pipeline outlet is arranged at the lower side of the T-shaped three-way pipe, connected to the water tank; the load loading mechanism is connected to the right side of the T-shaped three-way pipe, and is used to apply an axial load; the adjustable bellows system is used to fix the bellows specimen and adjust the effective length of the bellows specimen; the signal acquisition device is used to collect data of the bellows specimen under different working conditions. The present invention can simulate the actual working conditions of various bellows used to transmit cryogenic fluids by simulating the internal flow effect, the modal and flow-induced vibration characteristics of the bellows under different bending and stretching states.

Description

Technical Field

[0001] The invention belongs to the technical field of low-temperature fluid transmission, and more specifically is a metal bellows modal and flow-induced vibration test device. Background Art

[0002] Metal bellows is a cylindrical metal thin-walled pipe with a pleated shape. Because of its special structure, it can maintain good flexibility and pressure resistance in low-temperature environments, and can effectively compensate for the displacement caused by thermal expansion and contraction. In recent years, metal bellows have been widely used in the transmission of cryogenic liquids such as liquid hydrogen, liquid nitrogen, and liquefied natural gas. However, the corrugated structure that gives the metal bellows these excellent properties significantly enhances the coupling between the pipe and the internal fluid, which becomes the main cause of its vibration. In the process of high-speed fluid transmission, metal bellows are prone to fatigue failure, and the vibration induced by the internal flow is one of the key factors leading to fatigue. Therefore, it is necessary to propose an experimental device to measure the modal characteristics of the metal bellows (including modal and natural frequency) and the exciting force generated by the internal flow on the bellows, so as to determine the working conditions that may cause the resonance of the bellows and avoid fatigue failure caused by excessive vibration.

[0003] The fluid in the bellows will produce an additional mass effect on the inner wall of the metal bellows, significantly reducing its natural frequency. In addition, longer bellows usually bend to a certain extent during use, and the axial contraction caused by the cryogenic fluid may cause the pipe to be subjected to axial tension when the end is fixed. Different bending radii and axial tensions may affect the modal characteristics of the bellows. When the cryogenic liquid passes through the crest of the bellows, vortex shedding may occur due to boundary layer separation, thereby generating an exciting force on the wall. At the same time, the gas-liquid two-phase flow caused by the vaporization of the cryogenic liquid will also exert an exciting force on the wall of the bellows, and the wall exciting force caused by the internal flow will also be affected by the bending state of the bellows.

[0004] The existing vibration test device for metal bellows does not consider the influence of the flow in the pipeline on its vibration characteristics, and cannot apply axial load to the bellows to adjust its bending radius and axial tension. Most of these devices are designed for bellows expansion joints (short length), and cannot apply axial load to the bellows while the flow is flowing. CN113514216A introduces a modal test device for a metal diaphragm accumulator structure (whose core is constructed as a bellows expansion joint). The device uses a vibration test bench for modal test input, and uses a mass pressure plate to simulate the compression deformation of the bellows. CN209689862U shows a modal test method for a high-voltage switchgear (GIS) containing a bellows compensator, but does not achieve the conditions of flow and tension in the bellows. In addition, the existing test system for smooth pipelines does not simulate the tension of the pipeline, and only performs modal tests on the condition of fluid in it, with the purpose of comparing with the condition without fluid to determine the influence of the additional mass of the fluid on the vibration characteristics of the pipeline. Summary of the invention

[0005] In view of this, the present invention provides a metal bellows modal and flow-induced vibration test device, which tests the modal characteristics and internal flow exciting force frequency of the bellows by simulating the internal fluid, bending state and axial tension. It can simulate a variety of working conditions of bellows used to transmit cryogenic liquids, and provide a reference for avoiding resonance and fatigue failure of metal bellows.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A metal bellows modal and flow-induced vibration test device, comprising an adjustable bellows system, a circulation pipeline system and a signal acquisition device; the circulation pipeline system comprises an upstream pipeline, a downstream pipeline and a load loading mechanism arranged upstream and downstream of the adjustable bellows system; a water tank, a centrifugal pump and an air compressor are arranged in sequence on the upstream pipeline; the centrifugal pump is used to extract liquid medium from the water tank, and together with the air compressor, liquid and air are introduced into the upstream pipeline to form a gas-liquid two-phase flow; a T-shaped three-way pipe and a pipeline outlet are arranged in sequence on the downstream pipeline; the adjustable bellows system is connected to The left side opening of the T-shaped tee; the pipeline outlet is arranged at the lower side opening of the T-shaped tee, connected to the water tank, so that the upstream pipeline, the downstream pipeline and the bellows specimen in the adjustable bellows system form a circulation pipeline; the load loading mechanism is connected to the right side opening of the T-shaped tee, and is used to apply an axial load to the bellows; a bellows specimen is arranged in the adjustable bellows system, which is used to fix the bellows specimen and adjust the effective length of the bellows specimen; the signal acquisition end of the signal acquisition device is connected to the bellows specimen, and is used to collect data of the bellows specimen under different working conditions.

[0008] Furthermore, an exhaust valve and a liquid flow meter are sequentially arranged downstream of the centrifugal pump, the liquid flow meter is used to detect the liquid flow pumped into the upstream pipeline by the centrifugal pump; the exhaust valve is used to pre-empty the air pumped into the upstream pipeline by the centrifugal pump; and a valve is also arranged at the outlet end of the centrifugal pump.

[0009] Furthermore, the load loading mechanism is an actuator, and a blind plate is provided between the actuator and the right opening of the T-shaped tee pipe for sealing the pipeline; the actuator provides an axial load to the bellows specimen by connecting the blind plate.

[0010] Furthermore, the air compressor outlet is connected to the pipeline downstream of the liquid flow meter through a pipeline; a gas flow meter is also provided between the air compressor and the upstream pipeline for detecting the air flow of the air compressor entering the upstream pipeline.

[0011] Furthermore, a transparent acrylic tube and a rectifying plate are provided on the upstream pipeline downstream of the connection point between the air compressor and the upstream pipeline; the transparent acrylic tube is used to observe the flow state of the gas-liquid two-phase flow in the tube; the rectifying plate is used to eliminate the turbulence caused by the centrifugal pump in the upstream pipeline, thereby ensuring the stability of the fluid flow entering the bellows specimen.

[0012] Furthermore, a pressure gauge is provided on the pipeline downstream of the adjustable bellows system and connected to the left opening of the T-shaped tee, which is used to detect the pressure changes inside the bellows specimen; a rubber hose and a valve are successively provided between the lower opening of the T-shaped tee and the pipeline outlet; the valve is used to control the discharge of liquid in the downstream pipeline.

[0013] Furthermore, the adjustable bellows system includes a bellows specimen, a flange, a fixed support frame, a sliding support frame, a guide rail platform and a U-shaped clamp; the flange is fixedly arranged at the left and right ends of the bellows specimen, and is used to connect the bellows specimen into the circulation pipeline; the guide rail platform is used to support the setting of the fixed support frame and to support the sliding of the sliding support frame; the fixed support frame and the sliding support frame are both used to support the bellows specimen; the fixed support frame is fixedly arranged on the upstream side of the guide rail platform; the sliding support frame is slidably arranged on the downstream side of the guide rail platform, and is used to adjust the effective length of the bellows specimen.

[0014] Furthermore, the fixed support frame includes two groups of fixing units; each group of fixing units includes a truss and a fastener; the truss is fixed on the guide rail platform; an inverted U-shaped clamp is sandwiched between the two groups of fixing units to fix the corrugated pipe specimen; the fastener is used to fix the two groups of sliding units, thereby fixing the U-shaped clamp.

[0015] Furthermore, the sliding support frame includes two groups of sliding units, each group of sliding units includes a pulley, a truss and a fastener, the pulley is arranged at the lower end of the truss, and is used for the truss to walk on the guide rail platform; an inverted U-shaped clamping ring is clamped between the two groups of sliding units, which is used to limit the corrugated pipe specimen; the fastener is used to fix the two groups of sliding units, thereby fixing the U-shaped clamping ring.

[0016] Furthermore, the signal acquisition equipment includes a three-axis acceleration sensor, a dynamic data acquisition instrument and a computer; the three-axis acceleration sensor is arranged in three groups, evenly distributed in the middle part of the two fixed positions of the bellows specimen, bonded to the wave crest of the bellows specimen, and used to capture the vibration response of the bellows specimen under different working conditions; the input end of the dynamic data acquisition instrument is connected to the three-axis acceleration sensor, and the output end is connected to the computer, which is used to transmit the collected vibration acceleration signal to the computer for data processing and analysis.

[0017] The beneficial effects of the present invention are:

[0018] Compared with the prior art, the present invention discloses a metal bellows modal and flow-induced vibration test device, which can test the modes and natural frequencies of the flow-through metal bellows under different bending and stretching states, and clarify the modes and frequencies of the bellows that are most likely to resonate, so as to regulate other vibration sources in the pipeline to avoid them from exciting the resonance of the bellows. At the same time, the device can also measure the frequency of the exciting force on the pipeline wall caused by the single-phase turbulence and gas-liquid two-phase flow in the bellows and the resulting pipeline vibration response, determine the flow conditions that lead to a large vibration amplitude, and combine the bellows natural frequency test data to clarify the conditions that cause pipeline resonance. In general, the device can effectively prevent fatigue damage caused by excessive vibration of metal bellows, especially metal bellows used to transmit cryogenic fluids, through test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of the structure of the device of the present invention;

[0021] Figure 2 It is a partial enlarged schematic diagram of the sliding support frame of the present invention;

[0022] Among them, in the figure:

[0023] 1- Bellows specimen; 2- Flange; 3- Adjustable bellows system; 4- Centrifugal pump; 5- Valve; 6- Water tank; 7- Rectifier; 8- T-type tee; 9- Three-axis acceleration sensor; 10- Computer; 11- Liquid flow meter; 12- Pressure gauge; 13- Vibration damping pad; 14- Fixed support frame; 15- Sliding support frame; 16- Guide rail platform; 17- Blind plate; 18- Actuator; 19- Transparent acrylic tube; 20- Air compressor; 21- Gas flow meter; 22- Exhaust valve; 23- Rubber hose; 24- Pulley; 25- Truss; 26- Fasteners; 27- Elbow; 28- U-shaped clamp; 29- Dynamic data acquisition instrument. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Please see attached Figure 1-2 The present invention provides a metal bellows modal and flow-induced vibration test device, which includes an adjustable bellows system 3, a circulation pipeline system and a signal acquisition device.

[0026] The circulation pipeline system includes an upstream pipeline, a downstream pipeline and a load loading mechanism arranged upstream and downstream of the adjustable bellows system 3. A water tank 6, a centrifugal pump 4, an air compressor 20, a transparent acrylic tube 19 and a rectifier 7 are arranged in sequence on the upstream pipeline; the centrifugal pump 4 is used to extract liquid medium from the water tank 6; a liquid flow meter 11 is arranged downstream of the centrifugal pump 4, and the liquid flow meter 11 is an electromagnetic flow meter for detecting the liquid flow rate pumped into the upstream pipeline by the centrifugal pump 4; an exhaust valve 22 is arranged between the centrifugal pump 4 and the liquid flow meter 11, which is used to pre-empt the air pumped into the upstream pipeline by the centrifugal pump 4; a valve 5 is also arranged at the outlet end of the centrifugal pump 4; the outlet of the air compressor 20 is connected to the pipeline downstream of the liquid flow meter 11 through a pipeline, which is used to inject air into the upstream pipeline; a gas flow meter 21 is also arranged between the air compressor 20 and the upstream pipeline, which is used to detect the air flow rate of the air compressor 20 into the upstream pipeline. The centrifugal pump 4 draws liquid medium from the water tank 6, and enters the upstream pipeline after passing through the liquid flowmeter 11. The air compressor 20 injects air into the upstream pipeline through the gas flowmeter 21, and forms a gas-liquid two-phase flow with the body in the upstream pipeline. The exhaust valve 22 can pre-empt the air in the liquid to avoid interference with the data of the gas flowmeter 21. The transparent acrylic tube 19 is used to observe the flow state of the gas-liquid two-phase flow in the tube; the rectifying plate 7 is used to eliminate the turbulence caused by the centrifugal pump 4 in the upstream pipeline to ensure the stability of the fluid flow entering the bellows specimen 1. The elbow 27 arranged upstream of the transparent acrylic tube 19 and upstream of the rectifying plate 7 is wrapped with vibration-damping pads 13 upstream and downstream, which are used to absorb the vibration caused by the fluid flowing through the elbow, reduce the vibration interference of the non-test section pipeline, and ensure the accuracy of the test data of the test section of the bellows specimen 1.

[0027] The downstream pipeline is provided with a pressure gauge 12, a T-shaped three-way pipe 8, a rubber hose 23 and a pipeline outlet in sequence; the pressure gauge 12 is arranged on the pipeline downstream of the bellows test piece 1 and connected to the left opening of the T-shaped three-way pipe 8, and is located at the left opening of the T-shaped three-way pipe 8, and is used to detect the pressure change inside the bellows test piece 1. The rubber hose 23 is arranged at the lower opening of the T-shaped three-way pipe 8; a pipeline outlet is arranged downstream of the rubber hose 23, and is connected to the water tank 6, and the liquid in the downstream pipeline is discharged into the water tank 6, so that the upstream pipeline, the downstream pipeline and the bellows test piece 1 in the adjustable bellows system 3 form a circulation pipeline; a valve 5 is also arranged between the pipeline outlet and the rubber hose 23, which is used to control the discharge of the liquid in the downstream pipeline. The elbow 27 arranged downstream of the rubber hose 23 is wrapped with a vibration-damping pad 13 on both the upper and downstream sides, which is used to absorb the vibration generated by the fluid flowing through the elbow, reduce the vibration interference of the non-test section pipeline, and ensure the accuracy of the test data of the test section of the bellows test piece 1.

[0028] The load loading mechanism is an actuator 18, which is arranged on the right side of the T-shaped tee 8; the actuator 18 is used to apply an axial load to the bellows; the actuator 18 and the right opening of the T-shaped tee 8 are also provided with the blind plate 17 for sealing the pipeline. The actuator 18 can provide an axial load to the bellows specimen 1 by connecting the blind plate 17. A vibration-damping pad 13 is arranged on the pipeline between the blind plate 17 and the T-shaped tee 8 to absorb the vibration caused by the fluid flowing through the elbow.

[0029] Each component on the upstream pipeline and the downstream pipeline is connected by a stainless steel smooth pipe.

[0030] The adjustable bellows system 3 includes a bellows specimen 1, a flange 2, a fixed support frame 14, a sliding support frame 15, a guide rail platform 16 and a U-shaped clamping ring 28; the flange 2 is fixedly arranged at the left and right ends of the bellows specimen 1, and is used to connect the two ends of the bellows specimen 1 to the upstream pipeline and the downstream pipeline, and connect them into the circulation pipeline; the guide rail platform 16 is used to support the setting of the fixed support frame 14 and to support the sliding of the sliding support frame 15; the fixed support frame 14 and the sliding support frame 15 are both used to support the bellows specimen 1; the fixed support frame 14 is fixedly arranged on the upstream side of the guide rail platform 16; the sliding support frame 15 is slidably arranged on the downstream side of the guide rail platform 16, and is used to adjust the effective length of the bellows specimen 1.

[0031] The fixed support frame 14 includes two groups of fixing units; each group of fixing units includes a truss 25 and a fastener 26; the truss 25 is fixed on the guide rail platform 16; an inverted U-shaped clamping ring 28 is sandwiched between the two groups of fixing units for fixing the corrugated pipe specimen 1; the fastener 26 is used to fix the two groups of sliding units, thereby fixing the U-shaped clamping ring 28.

[0032] The sliding support frame 15 includes two sets of sliding units to make the sliding process more stable; each set of sliding units includes a pulley 24, a truss 25 and a fastener 26, the pulley 24 is arranged at the lower end of the truss 25, and is used for the truss 25 to walk on the guide rail 16; an inverted U-shaped clamp 28 is sandwiched between the two sets of sliding units to limit the position of the bellows specimen 1; the fastener 26 is used to fix the two sets of sliding units, thereby fixing the U-shaped clamp 28; the sliding support frame 15 can slide on the guide rail 16, and by adjusting the position of the sliding support frame 15, the length of the bellows specimen in the adjustable bellows system 3 can be changed to meet different test requirements. The length of the bellows specimen 1 needs to be greater than the length required for the turbulence in the bellows to fully develop.

[0033] After determining the length of the bellows specimen 1, use the actuator 18 to apply an axial load, control the bending radius and tension state of the bellows specimen 1, and simulate different stress conditions. The actuator 18 is connected to one end of the bellows specimen 1, and the displacement generated is absorbed by the T-shaped tee 8, the blind plate 17 and the rubber hose 23 to ensure that the bellows does not affect the flow of the pipeline during the stress process. After the adjustment is completed, use the U-shaped clamping ring 28 to fix the bellows specimen 1 on the sliding support frame 15 and the fixed support frame 14 to ensure that it remains stable during the test.

[0034] The signal acquisition equipment includes a triaxial acceleration sensor 9, a dynamic data acquisition instrument 29 and a computer 10. The triaxial acceleration sensor 9 is provided in three groups, evenly distributed in the middle part of the two fixed positions of the bellows specimen 1, and bonded to the wave crest of the bellows specimen 1, for capturing the vibration response of the bellows specimen 1 under different working conditions. The input end of the dynamic data acquisition instrument 29 is connected to the triaxial acceleration sensor 9, and the output end is connected to the computer 10, for transmitting the collected vibration acceleration signal to the computer 10 for data processing and analysis.

[0035] The test method of the present invention is as follows:

[0036] First, by adjusting the position of the sliding support frame 15 on the guide rail 16, the bellows specimen 1 is adjusted to the target test length to meet specific experimental requirements. Then, the actuator 18 is used to apply an axial load and adjust the bending radius or axial tension state of the bellows specimen 1 to simulate different stress conditions. After adjusting the length and stress state, the U-shaped clamping ring 28 is used to fix the bellows specimen 1 on the sliding support frame 15 and the fixed support frame 14 to ensure that it remains stable during the test and does not change position.

[0037] Next, start the centrifugal pump 4 and inject the liquid medium from the water tank 6 into the upstream pipeline. Adjust the exhaust valve 22 to remove the air in the pipeline. Air can be injected into the pipeline through the air compressor 20 to form a gas-liquid two-phase flow. Adjust the valve 5 and observe the liquid flow meter 11 and the gas flow meter 21 to control the flow rate and ratio of the medium. If the air compressor valve is closed, it will be a single-phase liquid flow.

[0038] Subsequently, the dynamic data acquisition instrument 29 and the computer 10 are turned on to monitor the vibration acceleration signal collected by the triaxial acceleration sensor 9 in real time. The mobile hammer percussion method is used to test the mode and natural frequency of the metal bellows when the tube is filled with liquid; the vibration acceleration signal of the bellows under different liquid and gas flow rates is tested to determine the single-phase flow velocity and gas-liquid two-phase flow state that cause pipeline resonance or large amplitude vibration, which can be observed through the transparent acrylic tube 19.

[0039] This test device can be used to comprehensively study the modal characteristics and flow-induced vibration response of metal bellows under different bending and stretching conditions. In particular, it can simulate the actual working conditions under low-temperature fluid transmission conditions (the pipeline is subjected to tensile loads and the gas-liquid two-phase flow is generated inside due to the evaporation of low-temperature liquid), providing an important experimental basis for preventing fatigue damage of metal bellows caused by excessive vibration.

[0040] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A metal bellows modal and flow-induced vibration test device, characterized in that: The invention comprises an adjustable bellows system (3), a circulation pipeline system and a signal acquisition device; the circulation pipeline system comprises an upstream pipeline, a downstream pipeline and a load loading mechanism arranged upstream and downstream of the adjustable bellows system (3); a water tank (6), a centrifugal pump (4) and an air compressor (20) are arranged in sequence on the upstream pipeline; the centrifugal pump (4) is used to extract liquid medium from the water tank (6) and, together with the air compressor (20), introduce liquid and air into the upstream pipeline to form a gas-liquid two-phase flow; a T-shaped three-way pipe (8) and a pipeline outlet are arranged in sequence on the downstream pipeline; the adjustable bellows system (3) is connected to the left and right sides of the T-shaped three-way pipe (8); The pipeline outlet is arranged at the lower opening of the T-shaped three-way pipe (8) and is connected to the water tank (6), so that the upstream pipeline, the downstream pipeline and the bellows test piece (1) in the adjustable bellows system (3) form a circulation pipeline; the load loading mechanism is connected to the right opening of the T-shaped three-way pipe (8) and is used to apply an axial load to the bellows; the bellows test piece (1) is arranged in the adjustable bellows system (3) and is used to fix the bellows test piece (1) and adjust the effective length of the bellows test piece (1); the signal acquisition end of the signal acquisition device is connected to the bellows test piece (1) and is used to collect data of the bellows test piece (1) under different working conditions; An exhaust valve (22) and a liquid flow meter (11) are sequentially arranged downstream of the centrifugal pump (4); the liquid flow meter (11) is used to detect the flow rate of liquid pumped into the upstream pipeline by the centrifugal pump (4); the exhaust valve (22) is used to pre-exhaust air pumped into the upstream pipeline by the centrifugal pump (4); and a valve (5) is also arranged at the outlet end of the centrifugal pump (4); The load loading mechanism is an actuator (18), and a blind plate (17) is further provided between the actuator (18) and the right opening of the T-shaped three-way pipe (8) for sealing the pipeline; the actuator (18) provides an axial load for the bellows test piece (1) by connecting to the blind plate (17); The outlet of the air compressor (20) is connected to the pipeline downstream of the liquid flow meter (11) through a pipeline; a gas flow meter (21) is also provided between the air compressor (20) and the upstream pipeline, for detecting the air flow rate of the air compressor (20) entering the upstream pipeline; A transparent acrylic tube (19) and a rectifying plate (7) are also provided on the upstream pipeline downstream of the connection point between the air compressor (20) and the upstream pipeline; the transparent acrylic tube (19) is used to observe the flow state of the gas-liquid two-phase flow in the tube; the rectifying plate (7) is used to eliminate turbulence caused by the centrifugal pump (4) in the upstream pipeline, thereby ensuring the stability of the flow of the fluid entering the bellows test piece (1).

2. The metal bellows modal and flow-induced vibration test device according to claim 1, characterized in that: A pressure gauge (12) is provided on the pipeline downstream of the adjustable bellows system (3) and connected to the left opening of the T-shaped three-way pipe (8) for detecting the pressure change inside the bellows test piece (1); a rubber hose (23) and a valve (5) are provided in sequence between the lower opening of the T-shaped three-way pipe (8) and the pipeline outlet; the valve (5) is used to control the discharge of liquid in the downstream pipeline.

3. The metal bellows modal and flow-induced vibration test device according to claim 1, characterized in that: The adjustable bellows system (3) comprises a bellows specimen (1), a flange (2), a fixed support frame (14), a sliding support frame (15), a guide rail platform (16) and a U-shaped clamping ring (28); the flange (2) is fixedly arranged at the left and right ends of the bellows specimen (1) and is used to connect the bellows specimen (1) to the circulation pipeline; the guide rail platform (16) is used to support the setting of the fixed support frame (14) and to support the sliding of the sliding support frame (15); the fixed support frame (14) and the sliding support frame (15) are both used to support the bellows specimen (1); the fixed support frame (14) is fixedly arranged on the upstream side of the guide rail platform (16); the sliding support frame (15) is slidably arranged on the downstream side of the guide rail platform (16) and is used to adjust the effective length of the bellows specimen (1).

4. The metal bellows modal and flow-induced vibration test device according to claim 3, characterized in that: The fixed support frame (14) comprises two groups of fixed units; each group of fixed units comprises a truss (25) and a fastener (26); the truss (25) is fixed on the guide rail platform (16); an inverted U-shaped clamping ring (28) is sandwiched between the two groups of fixed units for fixing the bellows test piece (1); the fastener (26) is used to fix the two groups of sliding units, thereby fixing the U-shaped clamping ring (28).

5. The metal bellows modal and flow-induced vibration test device according to claim 3, characterized in that: The sliding support frame (15) comprises two groups of sliding units, each group of sliding units comprises a pulley (24), a truss (25) and a fastener (26), the pulley (24) being arranged at the lower end of the truss (25) and being used for the truss (25) to move on the guide rail platform (16); an inverted U-shaped clamping ring (28) is sandwiched between the two groups of sliding units and is used for limiting the position of the corrugated pipe specimen (1); the fastener (26) is used to fix the two groups of sliding units, thereby fixing the U-shaped clamping ring (28).

6. The metal bellows modal and flow-induced vibration test device according to claim 1, characterized in that: The signal acquisition device comprises a triaxial acceleration sensor (9), a dynamic data acquisition instrument (29) and a computer (10); the triaxial acceleration sensor (9) is provided in three groups, evenly distributed in the middle part of two fixed positions of the bellows specimen (1), bonded to the wave crest of the bellows specimen (1), and used to capture the vibration response of the bellows specimen (1) under different working conditions; the input end of the dynamic data acquisition instrument (29) is connected to the triaxial acceleration sensor (9), and the output end is connected to the computer (10), and is used to transmit the collected vibration acceleration signal to the computer (10) for data processing and analysis.

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