In-situ measurement device and measurement method for viscosity coefficient of pyrolysis gas

Abstract

The invention discloses an in-situ measurement device and measurement method for the viscosity coefficient of pyrolysis gas, the in-situ measurement device comprises an experiment module, the experiment module is connected with a vacuum pump and an inert gas storage tank, a heat flow measurement assembly, an air pressure sensor and a pressure sensor are arranged in the experiment module, and a material to be measured is placed on the pressure sensor; the measuring device further comprises a heat source system used for heating the heat flow measuring assembly or the to-be-measured material and a temperature measuring assembly used for detecting the surface temperature of the to-be-measured material. The device has the advantages that the steady-state heat flow value of the heat source system can be recorded through the heat flow measuring assembly, then the heat flow value of the to-be-measured material is obtained, meanwhile, the pressure in the experiment module is recorded through the air pressure sensor, and the pressure sensor can obtain the mass flow rate of overflowed pyrolysis gas in real time; and calculating the dynamic change of the viscosity coefficient of the gas on the surface of the to-be-measured material along with the temperature through a pyrolysis inversion algorithm.

Description

Technical Field

[0001] The present invention relates to the field of thermal protection of aviation and aerospace materials, and in particular to an in-situ measuring device and a measuring method for the viscosity coefficient of pyrolysis gas. Background Art

[0002] In cutting-edge fields such as aerospace, resin-based composite materials have become the core materials of thermal protection structures due to their excellent specific strength, specific modulus and good molding processability. When these aircraft pass through the atmosphere at hypersonic speed, the surface and air rub violently, causing the temperature of the environment in which the resin-based composite materials are located to rise sharply, causing the gas generated by the pyrolysis of the material to flow inside the material and in the surrounding boundary layer, and its viscosity coefficient has a profound impact on the performance of the entire thermal protection system. On the one hand, it determines the permeation characteristics of the pyrolysis gas in the pore system structure of the composite material, thereby affecting the heat conduction path and heat dissipation efficiency inside the material. On the other hand, the viscosity coefficient of the pyrolysis gas is directly related to its cooling effect on the surface of the aircraft and its interaction with the external high-temperature and high-speed airflow, which is related to whether the aircraft can maintain structural integrity and stability in extreme thermal environments. If the viscosity coefficient of the pyrolysis gas cannot be accurately determined, the design of the thermal protection system can only rely on empirical formulas and approximate estimates, which will lead to a large deviation between the design plan and the actual needs. It may increase the weight of the aircraft and reduce performance due to overly conservative design, or it may cause flight accidents due to insufficient protection. Therefore, developing an accurate and reliable device and method for measuring the viscosity coefficient of pyrolysis gas of resin-based composite materials under high-temperature conditions is crucial to promoting the development of aerospace technology and ensuring aircraft safety.

[0003] At present, there are obvious deficiencies in the measurement technology for the high-temperature viscosity coefficient of pyrolysis gas. Traditional test methods are difficult to simulate the extreme operating conditions of hypersonic aircraft during actual flight, resulting in large deviations between the test results and the actual situation. Existing test equipment and technology also have bottlenecks in terms of accuracy, stability and scope of application, and cannot meet the requirements of thermal protection design for high-precision pyrolysis gas parameters. This makes the design of thermal protection systems lack reliable data support, greatly increasing the risk and cost of aircraft development.

[0004] The patent with application number "202210809476.4" discloses "a gas viscosity coefficient measuring device and its measuring method", and the patent with application number "202210180418.X" discloses "a liquid viscosity coefficient measuring device". Although the above patents involve the measurement of fluid viscosity coefficient, there are the following problems during use: First, the influence of temperature on the viscosity coefficient of pyrolysis gas is not considered; second, the influence of external air pressure on the viscosity coefficient of pyrolysis gas is not considered; third, a real-time measurement method for the change of pyrolysis gas viscosity coefficient with temperature during the pyrolysis of resin-based composite materials is not proposed. Summary of the invention

[0005] The purpose of the present invention is to provide an in-situ measurement device and method for the viscosity coefficient of pyrolysis gas, which not only takes into account the influence of temperature and air pressure on the viscosity coefficient, but also can measure the change of its viscosity coefficient in real time when the external temperature changes.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] An in-situ measuring device for the viscosity coefficient of pyrolysis gas comprises an experimental cabin connected to a vacuum pump and an inert gas storage tank, a heat flow measurement component, an air pressure sensor and a pressure sensor are arranged in the experimental cabin, and a material to be measured is placed on the pressure sensor;

[0008] The measuring device also includes a heat source system for heating the heat flow measuring component or the material to be measured and a temperature measuring component for detecting the surface temperature of the material to be measured.

[0009] Preferably, the measuring device further comprises:

[0010] An external source starting high pressure device connected to the heat source system;

[0011] A data acquisition system connected to the heat flow measurement component, air pressure sensor, pressure sensor, and temperature measurement component;

[0012] A cooling system that cools the back of the heat flow measurement component and the bottom of the pressure sensor.

[0013] Preferably, a first placement platform for placing a heat flow measurement component and a second placement platform for placing a pressure sensor are provided in the experimental chamber, and a sample table for accommodating a material to be tested is placed on the pressure sensor; the side wall of the experimental chamber is also provided with a placement chamber for accommodating an air pressure sensor.

[0014] Preferably, a sealing ring and a secondary sealing device are provided at the door of the experimental cabin, an observation window is provided at the front end of the experimental cabin, and a first window for the heat source system to pass through, a second window and a third window for the temperature measuring component to pass through are provided at the top of the experimental cabin;

[0015] The first window is located directly above the heat flow measurement component, and the second window is located directly above the material to be measured.

[0016] Preferably, the secondary sealing device comprises a threaded hole opened on the surface of the experimental cabin, a bolt is screwed into the threaded hole, and a gasket that can apply pressure to the cabin door is sleeved on the bolt.

[0017] Preferably, the heat source system comprises a bracket, a movable device placer is provided on the bracket, a laser is mounted on the device placer, a positioning hole is opened on the bracket, and a positioning key cooperating with the positioning hole is provided on the device placer.

[0018] Preferably, the present application also discloses an in-situ measurement method of the viscosity coefficient of pyrolysis gas, comprising the following steps:

[0019] S1. Install the heat flow measurement assembly, air pressure sensor, pressure sensor and the material to be tested in the experimental cabin;

[0020] S2. Start the vacuum pump to evacuate the experimental chamber;

[0021] S3, injecting inert gas into the experimental chamber through the inert gas storage tank;

[0022] S4. Use the heat source system to heat the heat flow measurement component and record the steady-state heat flow value;

[0023] S5. Use a heat source system to heat the material to be tested;

[0024] S6. When performing step S5, the temperature measuring component is synchronously operated to measure the surface temperature of the material to be tested, the mass flow rate of the pyrolysis gas overflow is measured by the pressure sensor, and the cabin pressure is measured by the air pressure sensor;

[0025] S7. Data processing based on pyrolysis inversion algorithm.

[0026] Preferably, the data processing in step S7 includes the following process:

[0027] The gas constant R, carbonization layer permeability K, and specimen top surface area S are used to measure the pyrolysis gas overflow mass flow rate. Substitute the surface temperature T and air pressure P into the following formula:

[0028]

[0029] The viscosity coefficient μ and the pyrolysis gas pressure gradient at the internal surface of the specimen can be obtained: The measured heat flux, surface temperature, air pressure and other parameters are substituted into the control equation, boundary conditions and initial conditions, and another pressure gradient is obtained by numerical solution. The relationship between the viscosity coefficient μ and the viscosity coefficient μ can be used to calculate the viscosity coefficient of the pyrolysis gas under certain ambient pressure conditions.

[0030] The governing equation is as follows:

[0031]

[0032] The boundary conditions are as follows:

[0033] p=p w x=x w

[0034]

[0035] The initial conditions are as follows:

[0036]

[0037] The meanings of the parameters in the formula are as follows:

[0038] K——Permeability (m 2 ); μ——viscosity coefficient (Pa·s); q——heat flux of hot wall (W / m 2 ); ——heat blocking coefficient (-); ξ——porosity (-); u——pyrolysis gas velocity (m / s); S——specimen area (m 2 ); A——pre-exponential factor; E——activation energy (J); n——reaction order (-); t——time (s); ρ——density (kg / m 3 );h——enthalpy value (J / kg);x——material thickness direction coordinate (m);k——thermal conductivity (W / (m·K));T——temperature (K); ——specimen mass flow rate (kg / s); ΔH——pyrolysis heat (J / kg); R——gas constant (J / (kg·K)); subscript g——gas; subscript p——interface between original material layer and pyrolysis layer; subscript c——interface between pyrolysis layer and carbonization layer; subscript w——material surface; subscript 1——original material layer; subscript 2——pyrolysis layer; subscript 3——carbonization layer.

[0039] The beneficial effects of the present invention are:

[0040] 1. The heat flow measurement component can record the steady-state heat flow value of the heat source system, and then obtain the heat flow value of the material to be tested. At the same time, the pressure in the experimental chamber can be recorded by the air pressure sensor. The pressure sensor can obtain the mass flow rate of the pyrolysis gas overflow in real time, and then calculate the dynamic change of the gas viscosity coefficient on the surface of the material to be tested with temperature through the pyrolysis inversion algorithm.

[0041] 2. The heat source system can be moved and accurately positioned above the experimental cabin to heat the heat flow measurement components and the material to be tested respectively, ensuring that the heat source provided is stable and reliable, thereby improving the accuracy of the test results.

[0042] 3. The secondary sealing device is used to achieve reliable sealing of the door of the experimental cabin to avoid heat leakage. At the same time, it is also equipped with a cooling system to quickly cool the equipment after the measurement is completed, which is convenient for the next test.

[0043] 4. The present invention also discloses an in-situ measurement method for the viscosity coefficient of pyrolysis gas, and calculates the viscosity coefficient based on the test data. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is the overall structural diagram of the measuring device;

[0045] Figure 2 It is a schematic diagram of the working process of the measuring device;

[0046] Figure 3 This is a schematic diagram of the structure of the experimental cabin in the measurement device;

[0047] Figure 4 It is a schematic diagram of the structure of the heat source system in the measuring device;

[0048] Figure 5 It is a structural schematic diagram of the secondary sealing device.

[0049] The drawings are only used for illustrative purposes and should not be construed as limitations on this patent. In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged, or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. DETAILED DESCRIPTION

[0050] The present invention is further described below in conjunction with the accompanying drawings.

[0051] The following is an explanation of some terms in this application:

[0052] Pyrolysis gas: When a hypersonic vehicle flies at high speed in the atmosphere, the intense friction with the air generates extremely high aerodynamic heat, which seriously threatens the structural safety of the vehicle. Resin-based composite materials have become one of the important materials for thermal protection of hypersonic vehicles due to their excellent performance. Under the action of aerodynamic heat, resin-based composite materials decompose to produce pyrolysis gas; the gas composition produced by the pyrolysis of different types of resin-based composite materials varies, and the common components mainly include methane (CH4), ethylene (C2H4), propylene (C3H6), carbon monoxide (CO), carbon dioxide (CO2), and water (H2O).

[0053] Viscosity coefficient: a physical quantity that measures the viscosity of a fluid. For the pyrolysis gas produced by the pyrolysis of resin-based composite materials, the viscosity coefficient indicates the property of the internal friction generated when there is relative motion between adjacent fluid layers inside the gas when the gas is flowing. The viscosity coefficient of pyrolysis gas is affected by many factors. On the one hand, it is closely related to the composition of the gas. Different pyrolysis products have different molecular structures and properties, which will make the viscosity coefficient different. On the other hand, temperature has a significant effect on the viscosity coefficient. Generally speaking, as the temperature of the pyrolysis gas increases, the molecular thermal motion intensifies, and the viscosity coefficient usually increases. At the same time, pressure will also have an effect on it. Under certain conditions, pressure changes will change the distance and interaction between gas molecules, thereby affecting viscosity. In the thermal protection system of hypersonic aircraft, it determines the flow characteristics of the pyrolysis gas in the carbonized layer, which in turn affects the heat transfer process and thermal protection effect.

[0054] In-situ measurement of pyrolysis gas viscosity coefficient: The pyrolysis gas generated by thermal decomposition of resin-based composite materials is directly measured based on the measuring device of the invention, and the relationship between the viscosity coefficient and temperature and air pressure is obtained in real time, which can truly reflect the composition and properties of the pyrolysis gas.

[0055] Importance of pyrolysis gas viscosity coefficient: Accurate measurement of pyrolysis gas viscosity coefficient can make aerodynamic heat and aerodynamic calculations more accurate, and provide accurate thermal and mechanical load data for thermal protection system design; combined with the viscosity coefficient, the thermal response and ablation rate of materials under the action of pyrolysis gas can be analyzed, providing a basis for selecting and improving thermal protection materials; based on the viscosity coefficient, the system structure and material layout can be optimized to improve the reliability and effectiveness of the thermal protection system.

[0056] Embodiment 1

[0057] like Figure 1 — Figure 3 As shown, the in-situ measuring device of the viscosity coefficient of pyrolysis gas includes an experimental chamber 3, and two inlet and outlet valves 302 are arranged on the side wall of the experimental chamber 3, which are respectively connected to the vacuum pump 1 and the inert gas storage tank 2, and a heat flow measurement component 17, an air pressure sensor 16 and a pressure sensor 13 are arranged in the experimental chamber 3, and a material to be measured 15 is placed on the pressure sensor 13;

[0058] The measuring device further comprises a heat source system 6 for heating the heat flow measuring component 17 or the material to be measured 15 and a temperature measuring component 4 for detecting the surface temperature of the material to be measured 15 .

[0059] In this embodiment, the heat flow measurement component 17 is a Gordon heat flow meter, the inert gas storage tank 2 is an argon gas tank, the temperature measurement component 4 is an infrared temperature measurement device located outside the experimental cabin 3, and the heat source system 6 is a laser heat source system. The ultimate vacuum degree of the vacuum pump is 5×10 -4Pa, argon purity ≥99.999%, inflation pressure range is adjustable from 0.1-5MPa.

[0060] Since the starting voltage of the strong laser providing the heat source is high voltage electricity, an external source starting high voltage device 5 is required as the starting voltage to activate the laser. In order to collect data of the heat flow measurement component 17, the air pressure sensor 16, the pressure sensor 13, and the temperature measurement component 4 in real time, a data acquisition system connected to the aforementioned devices is also provided. The data acquisition system includes a collector and an industrial computer 7, a data acquisition wire 8, and the data acquisition wire 8 is a shielded cable. The data acquisition system is connected to the following sensors through the data acquisition wire 8: the temperature signal T of the temperature measurement component 4 s , the pressure difference signal ΔP of the pressure sensor 13, and the cabin pressure signal P of the air pressure sensor 16 g As well as the heat flow signal Q0 of the heat flow measurement component 17, the industrial computer runs the data acquisition program to achieve multi-parameter synchronous acquisition and real-time display.

[0061] In order to timely cool the back of the heat flux measurement component 17 and the bottom of the pressure sensor 13, a cooling system 9 is also provided. The cooling system 9 adopts a circulating water cooling form and has a water pump, a water outlet pipe 10 and a water inlet pipe 11. The cooling circuit of the heat flux measurement component 17 is in close contact with the back of the heat flux measurement component 17 through a copper heat sink, and the cooling circuit of the pressure sensor 13 is integrated at its bottom.

[0062] The experimental chamber 3 is provided with a first placement platform 306 for placing the heat flux measurement component 17 and a second placement platform 305 for placing the pressure sensor 13. A sample table 14 for accommodating the material to be tested 15 is placed on the pressure sensor 13; the sample table 14 is made of high-temperature resistant alumina ceramics, and has a low thermal conductivity high-temperature resistant ceramic plate inside. The material to be tested 15 is placed on the ceramic plate, which can avoid three-dimensional heating of heat and ensure one-dimensional heat transfer of the test piece. The size requirement of the sample table 14 is to allow the material to be tested to be completely embedded, with no gaps around, to ensure that the pyrolysis gas only diffuses vertically above the material during the heating process; the pressure sensor 13 is located at the bottom of the sample table 14, and the pressure sensor can obtain the mass flow rate of the pyrolysis gas overflow in real time. Due to the reduction in the mass of the test piece caused by the pyrolysis gas overflow, the weight of the test piece is obtained through the pressure sensor, and the reduced weight is the weight of the pyrolysis gas. The side wall of the experimental chamber 3 is also provided with an air pressure sensor 16. The air pressure sensor 16 adopts a capacitive film sensor and is directly welded to the side wall of the chamber to eliminate pipeline delay. A placement cabin 307 may also be provided outside the air pressure sensor 16 to provide a certain degree of protection therefor.

[0063] like Figure 5As shown, the hatch of the experimental cabin 3 is provided with a sealing ring 304 and a secondary sealing device 12. A high temperature resistant rubber sealing ring 304 is embedded at the edge of the hatch. When the hatch is closed, the sealing ring 304 fits tightly with the hatch to block the flow of gas in the cabin from the outside air. The secondary sealing device 12 includes a threaded hole 1203 opened on the surface of the experimental cabin 3. A bolt 1201 is screwed into the threaded hole 1203. A metal gasket 1202 that can apply pressure to the hatch is sleeved on the bolt 1201. When the hatch is closed, the bolt 1201 is turned to apply pressure so that the metal gasket 1202 is tightly pressed on the hatch, making the seal with the cabin more reliable. The metal gasket 1202 is not easy to deform or age at high temperature, can withstand high temperature and pressure, and is suitable for harsh environments such as high temperature and high vacuum. The combination of the sealing ring 304 and the secondary sealing device 12 can improve the sealing effect.

[0064] An observation window 303 is provided at the front end of the experimental chamber 3, which is convenient for real-time observation of the experimental conditions in the chamber; a first window 308, a second window 309 and a third window 310 for the temperature measuring component 4 to pass through are provided on the top of the experimental chamber 3; the temperature measuring component 4 is located outside the third window 310. When the laser heat source heats the material to be tested, the temperature measuring component 4 can measure the surface temperature of the material to be tested through the third window 310. During installation, it is necessary to ensure that the infrared light beam of the temperature measuring component 4 is directly aimed at the center of the material to be tested to ensure the accuracy of the temperature measurement.

[0065] The first window 308, the second window 309 and the third window 310 are all sapphire windows. Since sapphire has the characteristics of high temperature resistance and high light transmittance, its melting point is as high as 2050°C, so it can withstand the high temperature environment generated by the laser in the experiment and has excellent light transmittance in the infrared and visible light bands, which is convenient for the temperature measurement component and the heat source laser beam to penetrate while ensuring the sealing.

[0066] The first window 308 is located directly above the heat flow measurement component 17. The diameter of the copper sensor of the heat flow measurement component 17 is strictly matched with the aperture of the first window 308, ensuring that the laser beam completely covers the surface of the heat flow measurement component 17 when passing through the first window 308, avoiding energy loss or edge effect caused by aperture mismatch during heat flow measurement, and ensuring data accuracy. The second window 309 is located directly above the material to be measured 15.

[0067] like Figure 4As shown, the heat source system 6 includes a bracket 601, a movable device placer 605 is arranged on the bracket 601, a laser is installed on the device placer 605, two positioning holes 602 are opened on the bracket 601, and a positioning key 604 cooperating with the positioning hole 602 is arranged on the device placer 605; the device placer 605 is also provided with a button 603 that can control the extension or retraction of the positioning key 604, the button 603 is connected to a spring, when not subject to external force, the positioning key 604 is extended under the elastic force of the spring; when the button 603 is pressed by external force, the positioning key 604 is retracted into the device placer 605. When the positioning key 604 is retracted, the device placement device 605 can drive the laser to move back and forth on the bracket 601. When the button 603 is released during the movement, the positioning key 604 is always subjected to the driving force extending outward. When the positioning key 604 moves to the alignment positioning hole 602, it will automatically enter the positioning hole 602. At this time, the device placement device 605 cannot move, and the positioning of the laser is realized. When the positioning key 604 enters the two positioning holes 602, the laser is respectively aligned with the first window 308 and the second window 309, which can realize the heating of the heat flow measurement component 17 or the material to be measured 15. When the device placement device 605 needs to be moved again, press the button 603 to retract the positioning key 604.

[0068] This embodiment also discloses an in-situ measurement method of the viscosity coefficient of pyrolysis gas, comprising the following steps:

[0069] S1, place the heat flow measurement assembly 17 on the first placement platform 306, install the air pressure sensor 16 into the placement cabin 307, place the pressure sensor 13 on the second placement platform 305, and place the sample table 14 and the material to be tested 15 in sequence;

[0070] S2, close the door, tighten the bolts 1201, and then start the vacuum pump 1 to evacuate the experimental chamber 3 to ensure that no oxidation reaction occurs during the pyrolysis of the material and burns the test piece;

[0071] S3, injecting inert argon gas into the experimental chamber 3 through the inert gas storage tank 2 to avoid oxidation reaction during the material pyrolysis process or air interference with gas viscosity measurement;

[0072] S4, moving the heat source system 6 to above the first window 308, heating the heat flux measurement component 17 with the power density required by the experiment, and recording the steady-state heat flux value;

[0073] S5, moving the heat source system 6 to above the second window 309, and using the heat source system 6 to heat the material to be tested 15;

[0074] S6. When performing step S5, the temperature measuring component 4 is started synchronously to measure the surface temperature of the material 15 to be tested, the mass flow rate of the pyrolysis gas overflow is measured by the pressure sensor 13, and the cabin pressure is measured by the air pressure sensor 16;

[0075] S7. Data processing based on pyrolysis inversion algorithm.

[0076] The data processing of step S7 includes the following process:

[0077] The gas constant R, carbonization layer permeability K, and specimen top surface area S are used to measure the pyrolysis gas overflow mass flow rate. Substitute the surface temperature T and air pressure P into the following formula:

[0078]

[0079] The viscosity coefficient μ and the pyrolysis gas pressure gradient at the internal surface of the specimen can be obtained: The relationship between the viscosity coefficient μ and the pyrolysis gas pressure gradient at the internal surface of the specimen The measured heat flux, surface temperature, air pressure and other parameters are substituted into the control equation, boundary conditions and initial conditions, and the combined numerical solution is used to obtain another pressure gradient. The relationship between the viscosity coefficient μ and the viscosity coefficient μ can be used to calculate the viscosity coefficient of the pyrolysis gas under certain ambient pressure conditions as it changes with temperature. It is worth noting that when the ambient pressure changes, the viscosity coefficient will also change accordingly.

[0080] The governing equation is as follows:

[0081]

[0082]

[0083] The boundary conditions are as follows:

[0084] p=p w x=x w

[0085]

[0086] The initial conditions are as follows:

[0087]

[0088] The meanings of the parameters in the formula are as follows:

[0089] K——Permeability (m 2 ); μ——viscosity coefficient (Pa·s); q——heat flux of hot wall (W / m 2 ); ——heat blocking coefficient (-); ξ——porosity (-); u——pyrolysis gas velocity (m / s); S——specimen area (m 2); A——pre-exponential factor; E——activation energy (J); n——reaction order (-); t——time (s); ρ——density (kg / m 3 );h——enthalpy value (J / kg);x——material thickness direction coordinate (m);k——thermal conductivity (W / (m·K));T——temperature (K); ——specimen mass flow rate (kg / s); ΔH——pyrolysis heat (J / kg); R——gas constant (J / (kg·K)); subscript g——gas; subscript p——interface between original material layer and pyrolysis layer; subscript c——interface between pyrolysis layer and carbonization layer; subscript w——material surface; subscript 1——original material layer; subscript 2——pyrolysis layer; subscript 3——carbonization layer.

[0090] The above embodiments do not impose any formal limitations on the shape, material, structure, etc. of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are within the protection scope of the technical solution of the present invention.

[0091] In the description of the present invention, it is necessary to understand that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the protection content of the present invention.

[0092] If the words "first", "second", etc. are used in this document to limit components, those skilled in the art should know that the use of "first" and "second" is only to facilitate the description of the present invention and simplify the description. Unless otherwise stated, the above words have no special meaning.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An in-situ measuring device for the viscosity coefficient of pyrolysis gas, comprising an experimental chamber (3), characterized in that: The experimental chamber (3) is connected to a vacuum pump (1) and an inert gas storage tank (2); a heat flow measurement component (17), an air pressure sensor (16) and a pressure sensor (13) are arranged in the experimental chamber (3); and a material to be tested (15) is placed on the pressure sensor (13); The measuring device also includes a heat source system (6) for heating a heat flow measuring component (17) or a material to be measured (15), and a temperature measuring component (4) for detecting the surface temperature of the material to be measured (15).

2. The in-situ measurement device for the viscosity coefficient of pyrolysis gas according to claim 1, characterized in that: Also includes: An external source starts a high pressure device (5) connected to a heat source system (6); A data acquisition system connected to the heat flow measurement component (17), the air pressure sensor (16), the pressure sensor (13), and the temperature measurement component (4); A cooling system (9) is provided for cooling the back side of the heat flow measurement component (17) and the bottom side of the pressure sensor (13).

3. The in-situ measurement device for the viscosity coefficient of pyrolysis gas according to claim 1, characterized in that: The experimental chamber (3) is provided with a first placement platform (306) for placing a heat flow measurement component (17) and a second placement platform (305) for placing a pressure sensor (13); a sample table (14) for accommodating a material to be tested (15) is placed on the pressure sensor (13); and a placement chamber (307) for accommodating an air pressure sensor (16) is also provided on the side wall of the experimental chamber (3).

4. The in-situ measurement device for the viscosity coefficient of pyrolysis gas according to claim 1, characterized in that: The door of the experimental cabin (3) is provided with a sealing ring (304) and a secondary sealing device (12); the front end of the experimental cabin (3) is provided with an observation window (303); the top of the experimental cabin (3) is provided with a first window (308) for the heat source system (6) to pass through, a second window (309) and a third window (310) for the temperature measurement component (4) to pass through; The first window (308) is located directly above the heat flow measurement component (17), and the second window (309) is located directly above the material to be measured (15).

5. The in-situ measurement device for the viscosity coefficient of pyrolysis gas according to claim 4, characterized in that: The secondary sealing device (12) comprises a threaded hole (1203) opened on the surface of the experimental cabin (3), a bolt (1201) is screwed into the threaded hole (1203), and a gasket (1202) capable of applying pressure to the cabin door is sleeved on the bolt (1201).

6. The in-situ measurement device for the viscosity coefficient of pyrolysis gas according to claim 1, characterized in that: The heat source system (6) comprises a bracket (601), a movable device placement device (605) is arranged on the bracket (601), a laser is installed on the device placement device (605), a positioning hole (602) is opened on the bracket (601), and a positioning key (604) cooperating with the positioning hole (602) is arranged on the device placement device (605).

7. An in-situ measurement method of pyrolysis gas viscosity coefficient, based on the in-situ measurement device of pyrolysis gas viscosity coefficient according to claim 1, characterized in that: The following steps are involved: S1, installing a heat flow measurement assembly (17), an air pressure sensor (16), a pressure sensor (13) and a material to be tested (15) in an experimental chamber (3); S2, starting the vacuum pump (1) to evacuate the experimental chamber (3); S3, injecting inert gas into the experimental chamber (3) through the inert gas storage tank (2); S4, using the heat source system (6) to heat the heat flow measurement component (17), and recording the steady-state heat flow value; S5, using the heat source system (6) to heat the material to be tested (15); S6. When performing step S5, the temperature measuring component (4) is synchronously operated to measure the surface temperature of the material to be tested (15), the mass flow rate of the pyrolysis gas overflow is measured by the pressure sensor (13), and the cabin pressure is measured by the air pressure sensor (16); S7. Data processing based on pyrolysis inversion algorithm.

8. The in-situ measurement method of the viscosity coefficient of pyrolysis gas according to claim 7, characterized in that: The data processing in step S7 includes the following steps: The gas constant R, carbonization layer permeability K, and specimen top surface area S are used to measure the pyrolysis gas overflow mass flow rate. Substitute the surface temperature T and air pressure P into the following formula: The viscosity coefficient μ and the pyrolysis gas pressure gradient at the internal surface of the specimen can be obtained: The measured heat flux, surface temperature, air pressure and other parameters are substituted into the control equation, boundary conditions and initial conditions, and another pressure gradient is obtained by numerical solution. The relationship between the viscosity coefficient μ and the viscosity coefficient μ can be used to calculate the viscosity coefficient of the pyrolysis gas under certain ambient pressure conditions. The governing equation is as follows: The boundary conditions are as follows: p=p w x=x w The initial conditions are as follows: The meanings of the parameters in the formula are as follows: K——Permeability (m 2 ); μ——viscosity coefficient (Pa·s); q——heat flux of hot wall (W / m 2 ); ——heat blocking coefficient (-); ξ——porosity (-); u——pyrolysis gas flow rate (m / s); S——Test piece area (m 2 ); A——pre-exponential factor; E——activation energy (J); n——reaction order (-); t——time(s); ρ——density (kg / m 3 ); h——enthalpy value (J / kg); x——Coordinate in the material thickness direction (m); k——thermal conductivity (W / (m·K)); T——temperature (K); ——mass flow rate of specimen (kg / s); ΔH——thermal decomposition heat (J / kg); R——Gas constant (J / (kg·K)) Subscript g—gas; Subscript p—interface between original material layer and pyrolysis layer; Subscript c—interface between pyrolysis layer and carbonization layer; Subscript w——material surface; Subscript 1—original material layer; Subscript 2—pyrolysis layer; Subscript 3—carbonized layer.

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