Pressure measuring device and method for small inner diameter pipeline under positive pressure low temperature alternating working condition

Abstract

This invention belongs to the field of wind tunnel testing technology and discloses a pressure measurement device and method for a very small inner diameter pipeline under positive pressure, low temperature, alternating operating conditions. The pressure measurement device for a very small inner diameter pipeline under positive pressure, low temperature, alternating operating conditions comprises a temperature-controllable vacuum insulation chamber, high-precision pressure and temperature measurement devices, a highly reliable reference pressure and temperature environment device, a stable positive pressure gas source, and a test gas input with a high dew point temperature. The pressure measurement method for a very small inner diameter pipeline under positive pressure, low temperature, alternating operating conditions solves the problem that very small inner diameter pressure measuring pipeline components cannot accurately test airtightness and permeability under low temperature conditions. It establishes a low-temperature test platform with controllable pressure and temperature conditions and high pressure detection accuracy, and has practical engineering value.

Description

Technical Field

[0001] This invention belongs to the field of wind tunnel testing technology, specifically relating to a pressure measurement device and method for a very small inner diameter pipeline under positive pressure low temperature alternating conditions. Background Technology

[0002] Currently, the ventilation and airtightness testing of pressure measurement pipelines for wind tunnel test models can only be conducted at room temperature. The pressure measurement pipelines of the test models in low-temperature test equipment are extremely small-diameter pipelines operating under positive pressure and low-temperature alternating conditions, with a temperature range of -196℃ to 25℃ and an inner diameter of 0.1mm to 0.3mm.

[0003] Existing pressure measurement devices and methods for normal temperature environments cannot simulate low-temperature test conditions, the accuracy of measuring instruments is low, and the pressure detection error is large due to the influence of ambient temperature fluctuations on the extremely small volume of gas inside the tested pipeline.

[0004] Currently, there is an urgent need to develop a pressure measurement device and method for pipelines with extremely small inner diameters under positive pressure, low temperature, and alternating operating conditions. Summary of the Invention

[0005] One technical problem to be solved by the present invention is to provide a pressure measuring device for a pipeline with an extremely small inner diameter under positive pressure and low temperature alternating conditions. Another technical problem to be solved is to provide a pressure measuring method for a pipeline with an extremely small inner diameter under positive pressure and low temperature alternating conditions, so as to overcome the defects of the prior art.

[0006] The main body of the pressure measuring device for a very small inner diameter pipeline under positive pressure low temperature alternating conditions of the present invention is a vacuum insulation chamber. The vacuum insulation chamber is a double-layered closed chamber with several external interfaces on the top flange surface. The pressure measuring device includes a reference pressure vessel placed inside the vacuum insulation chamber, a very small inner diameter pipeline test piece, several connecting valves connected to the external interfaces, thermometers and pressure gauges installed on the corresponding connecting valves, a solenoid valve control module for controlling the on / off state of the connecting valves, and a display module for displaying the measured values ​​of the thermometers and pressure gauges.

[0007] The pressure measuring device also includes thermometer #1 and thermometer #2 placed inside the vacuum insulation chamber, as well as liquid nitrogen Dewar, manual valve #1, helium source, manual valve #2, exhaust port, air pump, ambient temperature solenoid valve #1, ambient temperature solenoid valve #2, cryogenic solenoid valve, ambient temperature solenoid valve #3, pressure gauge #1, ambient temperature solenoid valve #4, pressure gauge #2, pressure gauge #5, ambient temperature solenoid valve #6, and pressure gauge #3 arranged around the vacuum insulation chamber.

[0008] The connecting valve circuit includes a gas replacement valve circuit, a gas environment valve circuit, a gas testing valve circuit, and a pressure measurement bypass circuit. The gas replacement valve circuit includes an air pump and a No. 3 ambient temperature solenoid valve connected in sequence. The gas environment valve circuit includes a liquid nitrogen Dewar, a No. 1 manual valve, and a cryogenic solenoid valve connected in sequence. The gas testing valve circuit includes a helium source, a No. 2 manual valve, a No. 1 ambient temperature solenoid valve, a reference pressure vessel, a No. 5 ambient temperature solenoid valve, a No. 1 thermometer, a minimum inner diameter pipe test piece, a No. 2 thermometer, a No. 1 pressure gauge, a No. 2 ambient temperature solenoid valve, and an exhaust port connected in sequence. The pressure measurement bypass circuit includes a No. 4 ambient temperature solenoid valve, a No. 2 pressure gauge, a No. 5 ambient temperature solenoid valve, and a No. 6 ambient temperature solenoid valve connected in sequence. One node on the pressure measurement bypass circuit is connected to the gas testing valve circuit, and the other node is connected to the display module through the No. 6 ambient temperature solenoid valve.

[0009] Furthermore, the external interfaces of the vacuum insulation chamber are connected by welding; all connecting valves and instrument cable interfaces are arranged on the top flange face of the vacuum insulation chamber; the interlayer vacuum degree of the vacuum insulation chamber is 1×10⁻⁶. -3 Pa, total leakage < 1×10 -6 Pam 3 / s.

[0010] Furthermore, the temperature range of the inner cavity of the vacuum insulation chamber is -196℃ to 25℃, and the temperature control accuracy is ±2℃; within the test temperature range, the pressure control accuracy of the test piece in the smallest inner diameter pipeline is 10Pa.

[0011] Furthermore, the core components of the reference pressure vessel are placed in an ice-water mixture, wrapped with multiple layers of insulation material, and the entire vessel is placed inside a vacuum shell.

[0012] Furthermore, the inner diameter range of the extremely small inner diameter pipeline test piece is 0.1 mm to 0.3 mm.

[0013] The pressure measurement method for a very small inner diameter pipeline under positive pressure low temperature alternating conditions of the present invention includes the following steps:

[0014] S10. Perform gas replacement;

[0015] Start the air pump and input high dew point clean air, which has been filtered, cooled and dehydrated, and purified by molecular sieve, into the vacuum insulation chamber through the No. 3 ambient temperature solenoid valve to replace the gas inside the vacuum insulation chamber.

[0016] S20. Establish a low-temperature environment;

[0017] Open the No. 1 manual valve, and the liquid nitrogen gas in the liquid nitrogen Dewar enters the inner cavity of the vacuum insulation chamber through the No. 1 manual valve and the cryogenic solenoid valve along the pipeline, and is sprayed onto the test piece with a very small inner diameter pipeline, forming a low temperature environment with controllable temperature and pressure in the inner cavity of the vacuum insulation chamber.

[0018] S30. Establish a stable positive pressure test gas;

[0019] Open manual valve #2. Helium from the helium source enters the vacuum insulation chamber through manual valve #2 and ambient temperature solenoid valve #1 along the pipeline. It then forms a stable positive pressure test gas through the reference pressure vessel. It then enters the extremely small inner diameter pipeline test piece through ambient temperature solenoid valve #5 along the pipeline. A stable positive pressure test gas is established in the extremely small inner diameter pipeline test piece. Finally, it is discharged through the exhaust port through ambient temperature solenoid valve #2.

[0020] S40. Perform pressure and temperature measurements of the stable positive pressure test gas;

[0021] Pressure gauge #1, ambient temperature solenoid valve #4, pressure gauge #2, ambient temperature solenoid valve #6, and pressure gauge #3 are used to detect the pressure of the test gas in the test specimen of the extremely small inner diameter pipeline by combining the on and off states of the solenoid valve control module; thermometer #1 and thermometer #2 are used to detect the temperature of the gas entering and exiting the test specimen of the extremely small inner diameter pipeline.

[0022] S50. Perform on / off control of each connected valve of the pressure measuring device and measure pressure and temperature;

[0023] The solenoid valve control module controls the on / off state of solenoid valves 1#, 2#, 3#, 4#, 5#, and 6# according to a preset program; the display module displays and records the detection results of pressure gauges 1#, 2#, and 3#, as well as thermometers 1# and 2#; thus realizing the on / off control of each connected valve of the pressure measuring device and the measurement of pressure and temperature.

[0024] The vacuum insulation chamber in the pressure measuring device for extremely small inner diameter pipelines under positive pressure low temperature alternating conditions of the present invention adopts a vacuum structure and a high-level sealing structure design, which can reduce the external size and weight of the test platform, reduce the loss of cold energy inside the chamber, prevent the leakage of liquid nitrogen, and improve refrigeration efficiency and safety.

[0025] The pressure measuring device for extremely small inner diameter pipelines under positive pressure low temperature alternating conditions of the present invention uses high dew point clean air that has been filtered, cooled, and purified by molecular sieves to replace the gas in the vacuum insulation chamber and raise the temperature during the test process, which solves the problems of icing and frosting on the surface of the test piece of the extremely small inner diameter pipeline; and uses helium as the test gas to improve the test safety performance.

[0026] The core component of the reference pressure vessel in the pressure measuring device for a very small inner diameter pipeline under positive pressure low temperature alternating conditions of the present invention is placed in an ice-water mixture and wrapped with multiple layers of heat insulation material and a vacuum shell, which solves the problem that the pressure of the gas in the very small volume inside the pipeline being measured is affected by the fluctuation of ambient temperature.

[0027] The solenoid valve control module in the pressure measuring device for extremely small inner diameter pipelines under positive pressure low temperature alternating conditions of the present invention can realize automatic control of different test temperature conditions and repeatability tests according to a preset program.

[0028] The display module in the pressure measuring device for a very small inner diameter pipeline under positive pressure low temperature alternating conditions of the present invention can realize high-frequency acquisition, recording and real-time display of test data under different test conditions.

[0029] The pressure measurement device for extremely small inner diameter pipelines under positive pressure low temperature alternating conditions of the present invention has a temperature-controllable vacuum insulation chamber, a high-precision pressure and temperature measurement device, a highly reliable reference pressure and temperature environment device, a stable positive pressure gas source, and a test gas input with a high dew point temperature. The pressure measurement method for extremely small inner diameter pipelines under positive pressure low temperature alternating conditions of the present invention solves the problem that extremely small inner diameter pressure measuring pipeline components cannot accurately test airtightness and ventilation under low temperature conditions, and establishes a low temperature test platform with controllable pressure and temperature conditions and high pressure detection accuracy, which has practical engineering value. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the pressure measuring device for a very small inner diameter pipeline under positive pressure low temperature alternating conditions according to the present invention.

[0031] In the diagram: 1. Liquid nitrogen Dewar; 2. 1# Manual valve; 3. Helium source; 4. 2# Manual valve; 5. Exhaust port; 6. Air pump; 7. 1# Ambient temperature solenoid valve; 8. 2# Ambient temperature solenoid valve; 9. Cryogenic solenoid valve; 10. 3# Ambient temperature solenoid valve; 11. 1# Pressure gauge; 12. 4# Ambient temperature solenoid valve; 13. 2# Pressure gauge; 14. 5# Ambient temperature solenoid valve; 15. 6# Ambient temperature solenoid valve; 16. 3# Pressure gauge; 17. Display module; 18. Solenoid valve control module; 19. Vacuum insulation chamber; 20. 1# Thermometer; 21. Reference pressure vessel; 22. Minimal inner diameter pipeline test piece; 23. 2# Thermometer. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] Example: The vacuum insulation chamber 19 in this example has an outer diameter of φ410mm and a length of 852mm.

[0034] like Figure 1As shown, the main body of the pressure measuring device for the extremely small inner diameter pipeline under positive pressure low temperature alternating conditions in this embodiment is a vacuum insulation chamber 19. The vacuum insulation chamber 19 is a double-layer closed chamber with several external interfaces on the top flange surface. The pressure measuring device includes a reference pressure vessel 21 placed inside the vacuum insulation chamber 19, an extremely small inner diameter pipeline test piece 22, several connecting valves connected to the external interfaces, thermometers and pressure gauges installed on the corresponding connecting valves, a solenoid valve control module 18 for controlling the on / off state of the connecting valves, and a display module 17 for displaying the measured values ​​of the thermometers and pressure gauges.

[0035] The pressure measuring device also includes thermometer 20 (No. 1) and thermometer 23 (No. 2) placed inside the vacuum insulation chamber 19, and liquid nitrogen Dewar 1, manual valve 2 (No. 1), helium source 3, manual valve 4 (No. 2), exhaust port 5, air pump 6, ambient temperature solenoid valve 7 (No. 1), ambient temperature solenoid valve 8 (No. 2), cryogenic solenoid valve 9, ambient temperature solenoid valve 10 (No. 3), pressure gauge 11 (No. 1), pressure gauge 13 (No. 4), pressure gauge 14 (No. 5), ambient temperature solenoid valve 15 (No. 6), and pressure gauge 16 (No. 3) arranged around the vacuum insulation chamber 19.

[0036] The connecting valve circuit includes a gas replacement valve circuit, a gas environment valve circuit, a gas testing valve circuit, and a pressure measurement bypass circuit. The gas replacement valve circuit includes an air pump 6 and a #3 ambient temperature solenoid valve 10 connected in sequence. The gas environment valve circuit includes a liquid nitrogen Dewar 1, a #1 manual valve 2, and a cryogenic solenoid valve 9 connected in sequence. The gas testing valve circuit includes a helium source 3, a #2 manual valve 4, a #1 ambient temperature solenoid valve 7, a reference pressure vessel 21, a #5 ambient temperature solenoid valve 14, a #1 thermometer 20, a minimum inner diameter pipe test piece 22, a #2 thermometer 23, a #1 pressure gauge 11, a #2 ambient temperature solenoid valve 8, and an exhaust port 5 connected in sequence. The pressure measurement bypass circuit includes a #4 ambient temperature solenoid valve 12, a #2 pressure gauge 13, a #5 ambient temperature solenoid valve 14, and a #6 ambient temperature solenoid valve 15 connected in sequence. One node on the pressure measurement bypass circuit is connected to the gas testing valve circuit, and the other node is connected to the display module 17 through the #6 ambient temperature solenoid valve 15.

[0037] Furthermore, the external interfaces of the vacuum insulation chamber 19 are connected by welding; all connecting valves and instrument cable interfaces are arranged on the top flange surface of the vacuum insulation chamber 19; the interlayer vacuum degree of the vacuum insulation chamber 19 is 1×10⁻⁶. -3 Pa, total leakage < 1×10 -6 Pam 3 / s.

[0038] Furthermore, the temperature range of the inner cavity of the vacuum insulation chamber 19 is -196℃ to 25℃, and the temperature control accuracy is ±2℃; within the test temperature range, the pressure control accuracy within the minimal inner diameter pipeline test piece 22 is 10Pa.

[0039] Furthermore, the core components of the reference pressure vessel 21 are placed in an ice-water mixture, wrapped with multiple layers of insulation material, and placed entirely within a vacuum shell.

[0040] Furthermore, the inner diameter of the extremely small inner diameter pipeline test piece 22 ranges from 0.1 mm to 0.3 mm.

[0041] The pressure measurement method for a very small inner diameter pipeline under positive pressure low temperature alternating conditions in this embodiment includes the following steps:

[0042] S10. Perform gas replacement;

[0043] Start the air pump 6 and input high dew point clean air that has been filtered, cooled and dehydrated, and purified by molecular sieve into the vacuum insulation chamber 19 through the No. 3 ambient temperature solenoid valve 10 to replace the gas inside the vacuum insulation chamber 19.

[0044] S20. Establish a low-temperature environment;

[0045] Open manual valve 2 (1), and liquid nitrogen gas in liquid nitrogen Dewar 1 enters the inner cavity of vacuum insulation chamber 19 through manual valve 2 (1) and cryogenic solenoid valve 9, and is sprayed onto the test piece 22 with a very small inner diameter pipeline, forming a low temperature and pressure controllable low temperature environment in the inner cavity of vacuum insulation chamber 19.

[0046] S30. Establish a stable positive pressure test gas;

[0047] Open manual valve 4 (2#). Helium from helium source 3 enters the inner cavity of vacuum insulation chamber 19 through manual valve 4 (2#) and ambient temperature solenoid valve 7 (1#). It then forms a stable positive pressure test gas through reference pressure vessel 21. It enters the extremely small inner diameter pipeline test piece 22 through ambient temperature solenoid valve 14 (5#). A stable positive pressure test gas is established in the extremely small inner diameter pipeline test piece 22. Finally, it is discharged through exhaust port 5 through ambient temperature solenoid valve 8 (2#).

[0048] S40. Perform pressure and temperature measurements of the stable positive pressure test gas;

[0049] Pressure gauge 11, ambient temperature solenoid valve 12, pressure gauge 13, ambient temperature solenoid valve 15, and pressure gauge 16, through the on / off combination of solenoid valve control module 18, detect the pressure of the test gas in the minimal inner diameter pipeline test piece 22; thermometer 10 and thermometer 23 detect the temperature of the gas entering and exiting the minimal inner diameter pipeline test piece 22.

[0050] S50. Perform on / off control of each connected valve of the pressure measuring device and measure pressure and temperature;

[0051] The solenoid valve control module 18 controls the on / off state of solenoid valves 7 (1# ambient temperature), 8 (2# ambient temperature), 9 (low temperature), 10 (3# ambient temperature), 12 (4# ambient temperature), 14 (5# ambient temperature), and 15 (6# ambient temperature) according to a preset program; the display module 17 displays and records the detection results of pressure gauges 11 (1#), 13 (2#), 16 (3#), 20 (1# thermometer), and 23 (2# thermometer) in real time; thus realizing the on / off control of each connected valve of the pressure measuring device and the measurement of pressure and temperature.

[0052] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. For those skilled in the art, all features disclosed in the present invention, or all steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way without departing from the principles of the present invention. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A pressure measuring device for a small inner diameter pipe under positive pressure and low temperature alternating conditions, characterized in that, The main body of the pressure measuring device is a vacuum insulated cabin (19), which is a double-layer closed cabin body, and a plurality of external interfaces are arranged on the top flange surface; the pressure measuring device comprises a reference pressure container (21) placed in the inner cavity of the vacuum insulated cabin (19), a pipe test piece (22) with a very small inner diameter, a plurality of connecting valve paths in communication with the external interfaces, thermometers and pressure gauges installed on the corresponding connecting valve paths, an electromagnetic valve control module (18) for controlling the on-off of the connecting valve paths, and a display module (17) for displaying the measurement values of the thermometers and pressure gauges. The pressure measuring device further comprises a 1# thermometer (20) and a 2# thermometer (23) placed in the inner cavity of the vacuum insulated cabin (19), and a liquid nitrogen Dewar (1), a 1# manual valve (2), a helium source (3), a 2# manual valve (4), an exhaust port (5), an air pump (6), a 1# normal-temperature electromagnetic valve (7), a 2# normal-temperature electromagnetic valve (8), a low-temperature electromagnetic valve (9), a 3# normal-temperature electromagnetic valve (10), a 1# pressure gauge (11), a 4# normal-temperature electromagnetic valve (12), a 2# pressure gauge (13), a 5# normal-temperature electromagnetic valve (14), a 6# normal-temperature electromagnetic valve (15) and a 3# pressure gauge (16) arranged around the vacuum insulated cabin (19). The connecting valve paths comprise a gas replacement valve path, a gas environment valve path, a gas test valve path and a pressure measurement bypass; the gas replacement valve path comprises the air pump (6) and the 3# normal-temperature electromagnetic valve (10) connected in sequence; the gas environment valve path comprises the liquid nitrogen Dewar (1), the 1# manual valve (2) and the low-temperature electromagnetic valve (9) connected in sequence; the gas test valve path comprises the helium source (3), the 2# manual valve (4), the 1# normal-temperature electromagnetic valve (7), the reference pressure container (21), the 5# normal-temperature electromagnetic valve (14), the 1# thermometer (20), the pipe test piece (22) with a very small inner diameter, the 2# thermometer (23), the 1# pressure gauge (11), the 2# normal-temperature electromagnetic valve (8) and the exhaust port (5) connected in sequence; the pressure measurement bypass comprises the 4# normal-temperature electromagnetic valve (12), the 2# pressure gauge (13), the 5# normal-temperature electromagnetic valve (14) and the 6# normal-temperature electromagnetic valve (15) connected in sequence, one node of the pressure measurement bypass is in communication with the gas test valve path, and the other node is in communication with the display module (17) through the 6# normal-temperature electromagnetic valve (15).

2. The pressure measuring device for a small-bore line under positive pressure and low temperature alternating conditions according to claim 1, characterized in that, The outer connection interface of the vacuum insulation cabin (19) is connected by welding; all connection valve paths and instrument cable interfaces are arranged on the top flange surface of the vacuum insulation cabin (19); the interlayer vacuum degree of the vacuum insulation cabin (19) is 1×10 -3 Pa. -6 Pa•m 3 / s.

3. The pressure measurement device for a small inside diameter pipe under positive pressure and low temperature alternating conditions according to claim 1, characterized by The temperature range of the inner cavity of the vacuum insulated cabin (19) is -196℃~25℃, and the temperature control accuracy is ±2℃; under the test temperature range, the pressure control accuracy in the pipe test piece (22) with a very small inner diameter is ±10Pa.

4. The pressure measurement device for small inside diameter tubing under positive pressure and low temperature alternating conditions of claim 1, wherein, The core component of the reference pressure container (21) is placed in an ice-water mixture, wrapped with multiple layers of thermal insulation materials, and placed in a vacuum shell as a whole.

5. The pressure measurement device for small inside diameter tubing under positive pressure and low temperature alternating conditions of claim 1, wherein, The inner diameter of the pipe test piece (22) with a very small inner diameter ranges from 0.1mm to 0.3mm.

6. The pressure measurement method for the small-bore pipe under the positive pressure low-temperature alternating condition, which is used in the pressure measurement device for the small-bore pipe under the positive pressure low-temperature alternating condition according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: S10. Perform gas replacement; Start air pump (6), through 3# normal temperature solenoid valve (10) to the vacuum insulated cabin (19) input after filtering dust, cooling water, molecular sieve high dew point clean air, to the vacuum insulated cabin (19) inner cavity gas replacement; S20. Establish low temperature environment; Open 1# manual valve (2), liquid nitrogen in liquid nitrogen dewar (1) through 1# manual valve (2) and low temperature solenoid valve (9) along the pipeline into the vacuum insulated cabin (19) inner cavity, spray on the small inner diameter pipeline test piece (22), in the vacuum insulated cabin (19) in the inner cavity form temperature and pressure controllable low temperature environment; S30. Establish stable positive test gas; Open 2# manual valve (4), helium in helium source (3) through 2# manual valve (4), 1# normal temperature solenoid valve (7) along the pipeline into the vacuum insulated cabin (19) inner cavity, after the reference pressure container (21) form stable positive test gas, along the pipeline through 5# normal temperature solenoid valve (14) into the small inner diameter pipeline test piece (22), in the small inner diameter pipeline test piece (22) to establish stable positive test gas, finally through 2# normal temperature solenoid valve (8) through the exhaust port (5) exhaust; S40. Pressure and temperature measurement of stable positive test gas; 1# pressure gauge (11), 4# normal temperature solenoid valve (12), 2# pressure gauge (13), 6# normal temperature solenoid valve (15), 3# pressure gauge (16) through the on-off combination of electromagnetic valve control module (18) to realize the detection of test gas pressure in the small inner diameter pipeline test piece (22); 1# thermometer (20), 2# thermometer (23) to detect the gas temperature in and out of the small inner diameter pipeline test piece (22); S50. The on-off control of each connection valve of the pressure measuring device and the pressure and temperature measurement; The electromagnetic valve control module (18) according to the preset program to 1# normal temperature solenoid valve (7), 2# normal temperature solenoid valve (8), low temperature solenoid valve (9), 3# normal temperature solenoid valve (10), 4# normal temperature solenoid valve (12), 5# normal temperature solenoid valve (14), 6# normal temperature solenoid valve (15) on-off control; Display module (17) real-time display 1# pressure gauge (11), 2# pressure gauge (13), 3# pressure gauge (16), 1# thermometer (20), 2# thermometer (23) detection results and record; Realize the on-off control of each connection valve of the pressure measuring device and the pressure and temperature measurement.

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