CN114878116A - Pipeline low temperature vibration test system and method - Google Patents

Abstract

The invention provides a pipeline low temperature vibration test system, including a multi-function console, a low temperature liquid storage tank, a first switch valve, a first low temperature liquid filling pipe, a pressure gauge, a second switch valve, an exhaust pipe, Air tightness inspection tube, pipeline fixing platform, automatic balance auxiliary support device, first connection tool, second connection tool, low temperature protection plate, vibration table, second filling tube, fourth switch valve, air pillow tube, pressure relief pipe, third switch valve, temperature sensor; the multifunctional console includes a nitrogen supply system; the cryogenic protection plate is installed on the upper end surface of the movable part of the automatic balance auxiliary support device; automatic balance auxiliary support The lower end face of the movable part of the device is connected with the vibrating table; the present invention provides a deep low temperature and high internal pressure environment for the pipeline test piece through the overall pipeline arrangement and cooperates with the external low temperature liquid nitrogen filling device, which is suitable for aerospace products. The pipeline low temperature vibration test provides a real simulation environment.

Description

Pipeline low temperature vibration test system and method

technical field

The invention relates to the technical field of vibration testing, in particular, to a system and method for low-temperature vibration testing of pipelines, and in particular, to a system and method for low-temperature vibration testing of pipelines of aerospace products.

Background technique

In order to comprehensively improve the overall level and capability of my country's aerospace products, meet the needs of future aerospace development, and maintain the status of my country's aerospace technology as a major power in the world's aerospace field, my country has carried out the research and development of a new generation of aerospace products. Different from traditional aerospace products that use solid or solid-liquid hybrid engine technology, the new generation of aerospace products uses advanced cryogenic liquid engines. How to ensure that the "heart" of cryogenic liquid engines works normally during rocket flight key problem. The piping system, as a crucial "aorta" connecting the engine and the fuel tank, needs to withstand harsh mechanical environments such as deep and low temperature, high-frequency vibration, and high pressure during flight. Whether it can transport fuel to the engine smoothly , is a prerequisite to ensure the normal operation of the engine, and even one of the key factors that determine the success or failure of rocket flight.

In order to ensure the reliability of aerospace products during flight, it is necessary to simulate the real dynamic environment of the pipeline system with deep low temperature and high internal pressure on the ground. big problem.

Patent document CN211729606U discloses a vibration table, comprising a base; an upper platform supported on the base; at least one group of vibration motor units installed on the side of the upper platform facing the base, each of the vibration motor units It includes two vibration motors, the two vibration motors are symmetrically arranged along the center line of the upper platform parallel to the first direction, and the rotation directions of the two vibration motors are opposite. However, this scheme does not have the real dynamic environment simulation of deep low temperature and high internal pressure.

SUMMARY OF THE INVENTION

In view of the defects in the prior art, the purpose of the present invention is to provide a system and method for low-temperature vibration testing of pipelines.

A pipeline low-temperature vibration test system provided according to the present invention includes a multi-function console, a low-temperature liquid storage tank, a first switch valve, a first low-temperature liquid filling pipe, a pressure gauge, a second switch valve, and an exhaust pipe , Air tightness inspection pipe, pipeline fixing platform, automatic balance auxiliary support device, first connection tool, second connection tool, low temperature protection plate, vibration table, second filling pipe, fourth switch valve, air pillow pipe, drain pressure pipe, third switch valve, temperature sensor; the multifunctional console includes a nitrogen supply system;

The first connecting tool and the second connecting tool are used to fix the pipeline test piece, and the first connecting tool and the second connecting tool are both connected with the pipeline test piece; the upper end of the pipeline test piece passes through the first connecting tool It is fixed on the pipeline fixing platform, the upper end of the pipeline test piece and the contact surface of the first connecting tool are provided with a temperature sensor, the first connecting tool and the pipeline fixing platform are not communicated with each other, and the bottom of the pipeline test piece passes through The second connection tool is connected with the cryogenic protection panel, the second connection tool is not communicated with the cryogenic protection panel, and the cryogenic protection panel is installed on the movable part of the automatic balance auxiliary support device The upper end face of the automatic balance auxiliary support device is connected to the lower end face of the movable part of the vibrating table;

The multi-function console is connected with the cryogenic liquid storage tank through an airtight inspection pipe, an exhaust pipe is arranged on the cryogenic liquid storage tank, and a second switch valve is arranged on the exhaust pipe; the bottom of the cryogenic liquid storage tank, The top is respectively provided with a first low-temperature liquid filling pipe and a gas pillow pipe, and both the first low-temperature liquid filling pipe and the gas pillow pipe are in communication with the first connecting tool; the first low-temperature liquid filling pipe is provided with There is a first switch valve; a pressure gauge and a pressure relief pipe are arranged on the air pillow pipe, and a third switch valve is installed on the pressure relief pipe;

The second filling pipe is communicated with the second connecting tool, and the second filling pipe is provided with a fourth on-off valve; the second filling pipe is used to connect the external low-temperature liquid nitrogen filling device;

The position of the cryogenic liquid storage tank is higher than the upper end of the pipeline test piece.

Preferably, a safety valve is provided on the cryogenic liquid storage tank.

Preferably, it also includes a first control line, a second control line, and a second control line;

The multi-function console further includes a control system, the first on-off valve, the second on-off valve and the third on-off valve are all solenoid valves, and the first on-off valve, the second on-off valve and the third on-off valve pass through respectively The first control line, the second control line, and the second control line are electrically connected with the control system of the multi-function console.

Preferably, the cryogenic protection panel is made of FRP material.

Preferably, the fourth on-off valve is a mechanical valve.

According to a pipeline low-temperature vibration test method provided by the present invention, the pipeline low-temperature vibration test system is adopted, and further comprises the following steps:

Step 1: Carry out an air tightness test on the pipeline low temperature vibration test system;

Step 2: perform gas replacement on the pipeline low temperature vibration test system;

Step 3: Filling the pipeline test piece and the cryogenic liquid storage tank with cryogenic liquid;

Step 4: Make sure the temperature of the pipeline test piece is -196℃～-185℃.

Step 5: pressurize the pipeline test piece, and use the automatic balance auxiliary support device to restore the original length of the pipeline test piece;

Step 6: Pressurize the pipeline specimen.

Step 7: Turn on the vibration table to apply vibration excitation to the pipeline specimen, and record the vibration test data through the measuring instrument.

Step 8: Depressurize and empty the pipeline low-temperature vibration test system.

Preferably, the step 1 includes:

Close the fourth on-off valve, the second on-off valve, and the third on-off valve, open the first on-off valve, and use the multi-function console to add nitrogen to the cryogenic liquid storage tank and pipeline test piece through the air-tight inspection tube, and pressurize When the pressure reaches 0.2MPa, the air pressure is maintained for 15min. If the pressure drop is less than 0.01MPa within 15min, it means that the air tightness of the whole test system is good. Finally, open the third switch valve to relieve the pressure of the test system.

Preferably, the step 2 includes:

Open the fourth on-off valve, the second on-off valve, and the first on-off valve, use the multi-function console to charge and release nitrogen into the pipeline system, and remove the water vapor in the pipeline for more than 10 minutes.

Preferably, the step 3 includes:

Open the fourth on-off valve, the second on-off valve and the first on-off valve, close the third on-off valve, connect the low-temperature liquid nitrogen filling device to the second filling pipe, and use the low-temperature liquid nitrogen filling device to fully preheat the pipeline. Cold, with the injection of liquid nitrogen, the cryogenic liquid nitrogen filling device injects cryogenic liquid nitrogen into the pipeline specimen through the second filling pipe, and then fills the cryogenic liquid storage tank through the first cryogenic liquid filling pipe , When the liquid nitrogen is discharged from the exhaust pipe, it means that the liquid nitrogen has filled the test pipeline and the cryogenic liquid storage tank, and the fourth switch valve and the second switch valve are closed to stop the filling of liquid nitrogen.

Preferably, the step 5 includes:

Close the second on-off valve and pressurize the pipeline system by the volatilization of liquid nitrogen in the cryogenic liquid storage tank and the pipeline specimen; during the pressurization process of the pipeline system, adjust the height of the airbag of the automatic balance auxiliary support device to increase the pressure on the pipeline. The position of the lower end of the test piece is adjusted so that the pipeline test piece returns to its original length.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention provides a deep low temperature and high internal pressure environment for the pipeline test piece through the overall pipeline arrangement and cooperates with the external low temperature liquid nitrogen filling device, and provides a real simulation for the pipeline low temperature vibration test of aerospace products. surroundings.

2. The invention effectively prevents the damage of the low temperature fluid to the vibrating table through the design of the low temperature protection plate.

3. The present invention controls the opening or closing of the solenoid valve through the multi-function console, precisely controls the pressure of the pipeline system, and provides a reliable guarantee for the test of the aerospace product and the successful completion of the flight mission of the aerospace product.

Description of drawings

Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic structural diagram of the present invention.

The figure shows:

Detailed ways

The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the inventive concept. These all belong to the protection scope of the present invention.

The present invention provides a pipeline low-temperature vibration test system, as shown in FIG. 1, including a multi-function console 1, a low-temperature liquid storage tank 2, a first switch valve 3, a first low-temperature liquid filling pipe 5, a pressure gauge 6. The second switch valve 7, the exhaust pipe 10, the airtight inspection pipe 11, the pipeline fixing platform 12, the automatic balance auxiliary support device 13, the first connection tool 151, the second connection tool 152, the cryogenic protection plate 16, the vibration Stage 17, second filling pipe 18, fourth switch valve 19, air pillow pipe 20, pressure relief pipe 21, third switch valve 22, temperature sensor 24; the multifunctional console 1 includes a nitrogen supply system.

The first connecting tool 151 and the second connecting tool 152 are used to fix the pipeline test piece 14, and the first connecting tool 151 and the second connecting tool 152 are both connected with the pipeline test piece 14; the pipeline test piece The upper end of 14 is fixed on the pipeline fixing platform 12 through the first connecting tool 151, the upper end of the pipeline test piece 14 and the contact surface of the first connecting tool 151 are provided with a temperature sensor 24, and the first connecting tool 151 and the pipe are provided with a temperature sensor 24. The road fixing platform 12 is not connected to each other; the bottom of the pipeline test piece 14 is connected to the cryogenic protection panel 16 through the second connection tool 152 , and the second connection tool 152 and the cryogenic protection panel 16 are not connected to each other. The cryogenic protection plate 16 is installed on the upper end surface of the movable part of the automatic balance auxiliary support device 13; the lower end surface of the movable part of the automatic balance auxiliary support device 13 is connected to the vibration table 17, specifically, the automatic balance The lower end surface of the movable part of the auxiliary support device 13 is connected to the moving coil of the vibration table 17 , and the moving coil of the vibration table can transmit the vibration excitation to the pipeline test piece 14 through the automatic balancing device. In a preferred example, the pipeline fixing platform 12 is a bracket structure, the bottom of the pipeline test piece 14 is connected to the second connection tool 152 by stainless steel screws, and the second connection tool 152 is connected to the cryogenic temperature through stainless steel screws. The protection plate 16 is connected, the cryogenic protection plate 16 is installed on the upper end surface of the movable part of the automatic balance auxiliary support device 13 through stainless steel screws, and the lower end surface of the movable part of the automatic balance auxiliary support device 13 is connected with the stainless steel screw. The vibrating table 17 is connected to the moving coil. In a preferred example, the automatic balance auxiliary support device 13 adopts the airbag-type vertical pressure self-balance auxiliary support device for vibration test in the patent number CN201611025392, and the automatic balance auxiliary support device 13 has movable parts of The upper end surface is the fixed table C1 surface in CN201611025392, and the lower end surface of the movable part of the automatic balance auxiliary support device 13 is the fixed table C2 surface in CN201611025392.

The multi-function console 1 is connected with the cryogenic liquid storage tank 2 through an airtight inspection pipe 11. The cryogenic liquid storage tank 2 is provided with an exhaust pipe 10, and the exhaust pipe 10 is provided with a second on-off valve 7; the The bottom and top of the cryogenic liquid storage tank 2 are respectively provided with a first cryogenic liquid filling pipe 5 and an air pillow pipe 20 , and the first cryogenic liquid filling pipe 5 and the air pillow pipe 20 are both connected to the first connection tool 151 The first low temperature liquid filling pipe 5 is provided with a first on-off valve 3; the air pillow pipe 20 is provided with a pressure gauge 6 and a pressure relief pipe 21; the pressure gauge 6 is used to monitor the pipeline test piece 14 A third on-off valve 22 is installed on the pressure relief pipe 21;

The second filling pipe 18 is communicated with the second connecting tool 152, and a fourth switching valve 19 is arranged on the second filling pipe 18. Preferably, the fourth switching valve 19 is arranged on the second filling pipe 18. Fill the end of tube 18. The second filling pipe 18 is used to connect the external low-temperature liquid nitrogen filling device, and the low-temperature liquid nitrogen filling device can fill the low-temperature liquid into the pipeline test piece 14 through the second filling pipe 18. The fourth on-off valve 19 can control the on-off of cryogenic liquid filling. In a preferred example, the second filling pipe 18 is covered with a heat-insulating and cold-preserving layer.

The position of the cryogenic liquid storage tank 2 is higher than the upper end of the pipeline test piece 14 to ensure that the cryogenic liquid can flow into the pipeline test piece 14 through the first cryogenic liquid filling pipe 5 .

In a preferred example, the cryogenic liquid storage tank 2 is provided with a safety valve 9, preferably, a safety valve 9 is provided on the top of the cryogenic liquid storage tank 2, and the safety pressure of the safety valve 9 can be adjusted according to the test pressure requirements , to ensure that the pressure in the cryogenic liquid storage tank 2 is stable.

In a preferred example, the fourth on-off valve 19 is a mechanical valve, and the pipeline low-temperature vibration test system further includes a first control line 4, a second control line 8, and a second control line 23; the first on-off valve 3 , the second on-off valve 7 and the third on-off valve 22 are all solenoid valves, the multi-function console 1 also includes a control system, the first on-off valve 3, the second on-off valve 7, and the third on-off valve 22 pass through the The first control line 4 , the second control line 8 , and the second control line 23 are electrically connected to the control system of the multi-function console 1 .

In a preferred example, the cryogenic protection panel 16 is made of glass fiber reinforced plastic. The use of FRP material can not only prevent the low temperature liquid from freezing the moving coil of the vibrating table 17 , but also ensure that the vibration excitation generated by the vibrating table 17 can be rigidly transmitted to the pipeline specimen 14 .

The invention also provides a pipeline low-temperature vibration test method, which adopts the pipeline low-temperature vibration test system, and further comprises the following steps:

Step 1: Carry out an air tightness test on the pipeline low temperature vibration test system. The step 1 includes: closing the fourth on-off valve 19, the second on-off valve 7, and the third on-off valve 22, opening the first on-off valve 3, and using the multi-function console 1 to pass the air-tight inspection pipe 11 to the cryogenic liquid storage tank. 2. Add nitrogen to the pipeline test piece 14, pressurize it to 0.2MPa, turn off the nitrogen supply switch of the multi-function console 1, suspend the supply of nitrogen, keep the air pressure for 15 minutes, and pass the pressure gauge of the multi-function console 1. Observe the pressure of the whole test system. If the pressure drop is less than 0.01MPa within 15min, it means that the whole test system is airtight. Finally, open the third switch valve 22 to release the pressure of the test system.

Step 2: Perform gas replacement on the pipeline low temperature vibration test system. The step 2 includes: opening the fourth on-off valve 19, the second on-off valve 7, and the first on-off valve 3, using the multi-function console 1 to charge and release nitrogen into the pipeline system, and remove the water vapor in the pipeline for more than 10 minutes .

Step 3: Filling the pipeline specimen 14 and the cryogenic liquid storage tank 2 with cryogenic liquid; the step 3 includes: opening the fourth on-off valve 19, the second on-off valve 7, and the first on-off valve 3, and closing the The third switch valve 22 connects the low-temperature liquid nitrogen filling device to the second filling pipe 18, and uses the low-temperature liquid nitrogen filling device to fully pre-cool the pipeline (ie, slowly fill liquid nitrogen), and as the liquid nitrogen is injected , the low-temperature filling device fills the low-temperature liquid into the pipeline test piece 14 through the second filling pipe 18, and then fills the low-temperature liquid storage tank 2 through the first low-temperature liquid filling pipe 5. When the exhaust pipe 10 When the liquid nitrogen is discharged, it means that the liquid nitrogen has filled the test pipeline and the cryogenic liquid storage tank 2, and the fourth switch valve 19 and the second switch valve 7 are closed to stop the filling of liquid nitrogen.

Step 4: Make sure that the temperature of the pipeline test piece 14 is -196°C to -185°C. Specifically, whether the pipeline test piece 14 is filled with low-temperature liquid is judged by the temperature value of the temperature sensor 24 . The step 5 includes: after the liquid nitrogen filling and pressurization are completed, observe whether the temperature of the temperature sensor 24 is between -196°C and -185°C. If it is greater than this temperature range, it means that the liquid nitrogen in the pipeline is not full. Open the first on-off valve 3 to make the liquid nitrogen in the cryogenic liquid storage tank 2 fill the pipeline test piece 14 to ensure that the pipeline test piece 14 is filled with liquid nitrogen throughout the test.

Step 5: Pressurize the pipeline test piece 14, and use the automatic balance auxiliary support device 13 to restore the original length of the pipeline test piece 14. The step 4 includes: closing the second switch valve 7, and relying on the volatilization of the liquid nitrogen in the cryogenic liquid storage tank 2 and the pipeline test piece 14 to pressurize the pipeline system; if the self-pressurization rate of the test system is too slow, it can be Nitrogen was charged into the test system through the multi-function console 1 for rapid pressurization. During the pressurization process of the pipeline system, the volatilized liquid nitrogen will make the pipeline test piece 14 elongate. The position of the lower end of the road test piece is adjusted to restore the original length of the pipe test piece 14 .

The principle and process of restoring the initial length of the pipeline test piece 14 are as follows: when the pipeline test piece 14 is elongated due to the volatilization process of the liquid nitrogen, the fixed table surface C1 of the automatic balance auxiliary support device 13 located under the pipeline test piece 14 will be damaged. The pipeline test piece 14 is driven by the elongation, thereby moving downward. At this time, the sensor of the automatic balance auxiliary support device 13 will record the value of the downward movement of the fixed table C1 (that is, the elongation of the pipeline test piece 14). ). On the premise that the position of the upper end of the pipeline test piece 14 remains unchanged, adjust the height of the airbag of the automatic balance auxiliary support device 13 according to the value of the downward movement of the fixed table C1, and use the automatic balance auxiliary support device 13 to make the lower end of the pipeline test piece 14 move upward. The displacement can make the elongated pipeline specimen 14 return to its original length.

Step 6: Maintain pressure on the pipeline test piece 14 . In a preferred example, the pressure holding time is 10 min. Specifically, when the pressure in the pipeline system reaches the pressure required by the test, the safety valve 9 adjusts and maintains the pressure in the pipeline system at this time.

Step 7: Turn on the vibration table 17 to apply vibration excitation to the pipeline test piece 14, and record the vibration test data through the measuring instrument. Specifically, after the pressure holding in step 6 is completed, the vibrating table 17 is turned on, and vibration excitation is applied to the pipeline specimen 14 by controlling the vibrating table 17 according to the test conditions, and parameters such as acceleration, strain, and temperature are recorded by the measuring instrument.

Step 8: Depressurize and empty the pipeline low-temperature vibration test system. Specifically, after the test is completed, open the second on-off valve 7 to release pressure, when the gauge pressure of the pressure gauge on the cryogenic liquid storage tank 2 is released to 0, close the third on-off valve 22 and open the fourth on-off valve 19 Evacuate the remaining liquid nitrogen and nitrogen in the pipeline test piece 14 .

The invention provides a pipeline low temperature vibration test system and method which can be applied to aerospace products, which can simulate the environment of deep low temperature and high internal pressure, meet the requirements of coupling test of large acceleration level, and provide low temperature vibration test of pipelines of aerospace products. Experiments provide a realistic simulation environment.

The present invention realizes the automatic pressure balance function through the automatic balance auxiliary support device 13. Specifically, in step 5, when the pipeline test piece 14 is pressurized, the pipeline test piece 14 will automatically balance the auxiliary support device. 13 generates pressure, and the automatic balance auxiliary support device 13 can balance this part of the pressure due to the design of the air bag, thereby preventing the vibration table 17 from being damaged due to the partial pressure directly loading on the vibration table 17 . Therefore, the present invention can effectively balance the pressure of the internal pressure of the pipeline test piece 14 on the vibration table 17 through the automatic balance auxiliary support device 13 to increase the vibration level.

In addition, the present invention effectively prevents the low temperature fluid from damaging the vibration system (such as the vibration table 17 ) through the design of the cryogenic protection plate 16 and the like. In the present invention, the pipeline test piece 14 is connected with the cryogenic liquid storage tank 2 through the air pillow pipe, so as to keep the pressure in the two consistent, so as to ensure that the cryogenic liquid in the cryogenic liquid storage tank can be filled into the pipeline test piece at any time 14. The present invention also controls the opening or closing of the solenoid valve through the multifunctional console 1, and precisely controls the pressure of the pipeline system, thereby providing a reliable guarantee for the test of the aerospace product and the successful completion of the flight mission of the aerospace product.

In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", The orientation or positional relationship indicated by "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying the indicated device. Or elements must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as a limitation of the present application.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essential content of the present invention. The embodiments of the present application and features in the embodiments may be combined with each other arbitrarily, provided that there is no conflict.

Claims (10)

1. A pipeline low-temperature vibration test system is characterized by comprising a multifunctional control console (1), a low-temperature liquid storage tank (2), a first switch valve (3), a first low-temperature liquid filling pipe (5), a pressure gauge (6), a second switch valve (7), an exhaust pipe (10), an air tightness inspection pipe (11), a pipeline fixing platform (12), an automatic balance auxiliary supporting device (13), a first connecting tool (151), a second connecting tool (152), a low-temperature protection plate (16), a vibration table (17), a second filling pipe (18), a fourth switch valve (19), an air pillow pipe (20), a pressure relief pipe (21), a third switch valve (22) and a temperature sensor (24); the multifunctional console (1) comprises a nitrogen supply system;

the first connecting tool (151) and the second connecting tool (152) are used for fixing the pipeline test piece (14), and the first connecting tool (151) and the second connecting tool (152) are communicated with the pipeline test piece (14); the upper end of a pipeline test piece (14) is fixed on a pipeline fixing platform (12) through a first connecting tool (151), a temperature sensor (24) is arranged on the contact surface of the upper end of the pipeline test piece (14) and the first connecting tool (151), the first connecting tool (151) is not communicated with the pipeline fixing platform (12), the bottom of the pipeline test piece (14) is connected with a low-temperature protection plate (16) through a second connecting tool (152), the second connecting tool (152) is not communicated with the low-temperature protection plate (16), and the low-temperature protection plate (16) is installed on the upper end face of a movable part of an automatic balance auxiliary supporting device (13); the lower end face of a movable part of the automatic balance auxiliary supporting device (13) is connected with a vibrating table (17);

the multifunctional console (1) is connected with the low-temperature liquid storage tank (2) through an air tightness inspection pipe (11), an exhaust pipe (10) is arranged on the low-temperature liquid storage tank (2), and a second switch valve (7) is arranged on the exhaust pipe (10); the bottom and the top of the low-temperature liquid storage tank (2) are respectively provided with a first low-temperature liquid filling pipe (5) and an air pillow pipe (20), and the first low-temperature liquid filling pipe (5) and the air pillow pipe (20) are both communicated with the first connecting tool (151); a first switch valve (3) is arranged on the first low-temperature liquid filling pipe (5); a pressure gauge (6) and a pressure relief pipe (21) are arranged on the air pillow pipe (20), and a third switch valve (22) is arranged on the pressure relief pipe (21);

the second filling pipe (18) is communicated with a second connecting tool (152), and a fourth switch valve (19) is arranged on the second filling pipe (18); the second filling pipe (18) is used for connecting an external low-temperature liquid nitrogen filling device;

the position of the low-temperature liquid storage tank (2) is higher than the upper end of the pipeline test piece (14).

2. Pipeline cryogenic vibration test system according to claim 1, characterized in that a safety valve (9) is provided on the cryogenic liquid tank (2).

3. The pipeline low-temperature vibration test system according to claim 1, further comprising a first control line (4), a second control line (8), a second control line (23);

the multifunctional control console (1) further comprises a control system, the first switch valve (3), the second switch valve (7) and the third switch valve (22) are all electromagnetic valves, and the first switch valve (3), the second switch valve (7) and the third switch valve (22) are respectively electrically connected with the control system of the multifunctional control console (1) through a first control line (4), a second control line (8) and a second control line (23).

4. The pipeline low-temperature vibration test system according to claim 1, wherein the low-temperature protection plate (16) is made of glass fiber reinforced plastic materials.

5. Pipeline cryogenic vibration test system according to claim 1, characterized in that the fourth switching valve (19) is a mechanical valve.

6. A pipeline low-temperature vibration test method, characterized in that the pipeline low-temperature vibration test system of any one of claims 1 to 5 is adopted, and the method further comprises the following steps:

step 1: carrying out an airtight test on the pipeline low-temperature vibration test system;

step 2: performing gas replacement on the pipeline low-temperature vibration test system;

and step 3: filling the pipeline test piece (14) and the low-temperature liquid storage tank (2) with low-temperature liquid;

and 4, step 4: ensuring that the temperature of the pipeline test piece (14) is between-196 ℃ and-185 ℃;

and 5: pressurizing the pipeline test piece (14), and recovering the initial length of the pipeline test piece (14) by using the automatic balance auxiliary supporting device (13);

step 6: maintaining the pressure of the pipeline test piece (14);

and 7: starting a vibration table (17) to apply vibration excitation to the pipeline test piece (14), and recording vibration test data through a measuring instrument;

and 8: and carrying out pressure relief and evacuation on the pipeline low-temperature vibration test system.

7. The pipeline low-temperature vibration test method according to claim 6, wherein the step 1 comprises the following steps:

and (3) closing the fourth switch valve (19), the second switch valve (7) and the third switch valve (22), opening the first switch valve (3), adding nitrogen into the low-temperature liquid storage tank (2) and the pipeline test piece (14) through the air tightness inspection pipe (11) by using the multifunctional console (1), pressurizing to 0.2MPa, keeping the air pressure for 15min, if the pressure drop is less than 0.01MPa within 15min, indicating that the air tightness of the whole test system is good, finally opening the third switch valve (22), and unloading the pressure of the test system.

8. The pipeline low-temperature vibration test method according to claim 6, wherein the step 2 comprises:

and opening the fourth switch valve (19), the second switch valve (7) and the first switch valve (3), and filling nitrogen into the pipeline system by using the multifunctional console (1) to remove water vapor in the pipeline for more than 10 min.

9. The pipeline low-temperature vibration test method according to claim 6, wherein the step 3 comprises:

the fourth switch valve (19), the second switch valve (7) and the first switch valve (3) are opened, the third switch valve (22) is closed, the low-temperature liquid nitrogen filling device is connected with the second filling pipe (18), the pipeline is fully pre-cooled by using the low-temperature liquid nitrogen filling device, along with the filling of the liquid nitrogen, the low-temperature liquid nitrogen filling device fills the low-temperature liquid nitrogen into the pipeline test piece (14) through the second filling pipe (18), and then fills the low-temperature liquid into the low-temperature liquid storage tank (2) through the first low-temperature liquid filling pipe (5), when the liquid nitrogen is discharged from the exhaust pipe (10), the test pipeline and the low-temperature liquid storage tank (2) are filled with the liquid nitrogen, and the fourth switch valve (19) and the second switch valve (7) are closed to stop filling the liquid nitrogen.

10. The pipeline low-temperature vibration test method according to claim 6, wherein the step 5 comprises:

closing the second switch valve (7), and pressurizing the pipeline system by means of volatilization of liquid nitrogen in the low-temperature liquid storage tank (2) and the pipeline test piece (14); in the pressurization process of the pipeline system, the height of the air bag of the automatic balance auxiliary supporting device (13) is adjusted to adjust the position of the lower end of the pipeline test piece, so that the pipeline test piece is restored to the initial length.

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