A solid propellant thermal gravimetric and high initial temperature burning rate in-situ testing system

Abstract

This invention discloses an in-situ testing system for the thermogravimetric loss and high initial temperature burning rate of solid propellants, relating to the field of solid propellant technology. The invention uses a PID heating controller to adjust the heating temperature and duration of the solid propellant charge, a high-precision force sensor to test the weight loss rate of the charge during heating, a high-speed thermal imager to record the surface temperature distribution during the thermal response of the charge, and a laser to perform non-contact ignition of the high initial temperature charge and in-situ measurement of its burning rate. The testing system proposed in this invention can test the weight loss rate of solid propellants under programmed temperature rise heat loads and achieves in-situ testing of the high initial temperature burning rate of solid propellants. This is significant for research on the correlation between the thermal decomposition characteristics and combustion performance of solid propellants, as well as their thermal safety and combustion response. Compared to existing designs, this invention offers higher visualization, more diverse in-situ measurable data, smaller overall size, safer and more reliable operation, and simpler operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of solid power technology, and in particular to a solid propellant thermal weight loss rate and high initial temperature thermal damage propellant strip burning rate in-situ testing system under programmed temperature heating load. BACKGROUND

[0002] Solid propellant is a solid-state mixture of energy and working medium for solid rocket engine to obtain thrust, which is an energetic material and belongs to one type of gunpowder. Solid propellant is inevitably subjected to thermal stimulation due to heat source, friction or impact heat generation during production, storage, transportation and use. A large number of propellant combustion accidents caused by thermal stimulation have occurred in the history of solid propellant development, often causing casualties and production line damage. Therefore, the study of thermal safety of solid propellant is of great significance to improve the safety of aerospace engines and weapon equipment. Therefore, since the advent of solid propellant, the thermal safety of different types of propellants has been an important issue.

[0003] Under the action of thermal load, the active components in the solid propellant will decompose to change the chemical composition of the remaining part. The gas escaping after the decomposition of the active components will cause the thermal weight loss of the propellant. The decomposition of the components, thermal stress and other reasons will also cause thermal damage (microstructure change, such as the generation of pores and cracks) to the propellant. In general, thermal load will cause changes in the chemical composition and microstructure of the propellant, which will further affect the ignition threshold and ignition response intensity of the propellant. Therefore, researchers have been committed to revealing the correlation between the thermal decomposition characteristics and the combustion performance of the propellant and the thermal ignition response mechanism of the propellant. In order to study the response law of the solid propellant under high temperature load stimulation, researchers have designed various fast and slow baking and burning equipment and gradually established standards. It is found that the baking and burning response of the propellant is closely related to the burning rate characteristics after thermal damage, which is affected by the propellant formula, shell constraint and thermal load history. Therefore, the key to studying the baking and burning response mechanism of the propellant is to establish the relationship between the thermal decomposition characteristics and the combustion performance. The existing test systems for studying the correlation between thermal decomposition and burning rate characteristics are all ex situ tests, that is, the thermal treatment and burning rate test are carried out ex situ. The error introduced by the change of the initial temperature of the propellant is an inherent limitation of this test method. In addition, the invasive temperature measurement method such as inserting a thermocouple into the propellant and the contact ignition method such as using an electric heating wire to ignite will cause large errors in the propellant burning rate test results.

[0004] In order to solve the above problems, the present application provides a solid propellant thermal weight loss and high initial temperature burning rate in-situ testing system. SUMMARY

[0005] The purpose of the present application is to provide a solid propellant thermal weight loss and high initial temperature burning rate in-situ testing system to solve the problems raised in the background art:

[0006] The existing research thermal decomposition and burning rate correlation test system is all ex situ test, that is, the thermal treatment and the burning rate test are carried out in different places, and the error caused by the change of the initial temperature of the propellant is the inherent limitation of this test mode; in addition, the invasive temperature measurement mode such as inserting a thermocouple into the propellant and the contact ignition mode such as using an electric heating wire to ignite will cause a large error in the propellant burning rate test result.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0008] A solid propellant thermal weight loss and high initial temperature burning rate in-situ test system, characterized in that the test system comprises a test mechanism, a heating controller, a charge amplifier, a data acquisition card, a high-speed infrared thermal imager and a computer;

[0009] The heating controller is matched with the test mechanism to control and record the heating temperature of the test mechanism;

[0010] The charge amplifier is used to amplify the signal generated by the test mechanism;

[0011] The data acquisition card is used to collect the signal amplified by the charge amplifier;

[0012] The high-speed infrared thermal imager is used to shoot and monitor the image data in the test process of the test mechanism;

[0013] The computer is used to collect the temperature data from the heating controller, the signal data from the data acquisition card and the image data from the high-speed infrared thermal imager;

[0014] The test mechanism comprises a laser, a bracket, an end cover, a clamp, an infrared germanium glass box, heat conducting oil, a thermocouple, a U-shaped heating pipe, a high-temperature resistant quartz tube, a rubber ring, a force sensor and a propellant stick; the heat conducting oil is contained in the infrared germanium glass box, the end cover is fixedly arranged at the top end of the infrared germanium glass box, the force sensor is fixedly arranged at the center of the top surface of the end cover, the open end of the high-temperature resistant quartz tube is clamped and connected to the rubber ring, and the rubber ring is placed on the force sensor; the rubber ring is designed in a ring structure, through holes are arranged at the center of the rubber ring and the end cover, the end of the high-temperature resistant quartz tube penetrates through the through hole and is placed in the heat conducting oil, and the propellant stick is arranged in the high-temperature resistant quartz tube; the U-shaped heating pipe is connected to the end cover, and the thermocouple is integrally arranged in the U-shaped heating pipe; the bracket is a truss structure and is clamped and fixed to the end cover through the clamp, and the laser is fixedly connected to the top end of the bracket.

[0015] Preferably, the heating controller is connected to the upper two ends of the U-shaped heating tube, and the U-shaped heating tube is heated by the input signal of the thermocouple and the PID control module. The U-shaped design is conducive to uniform heating of the heat conducting oil through heat convection.

[0016] Preferably, the charge amplifier is used to amplify the signal collected by the force sensor. The force sensor is selected from high-precision high-temperature-resistant sensors, and the maximum working temperature is ≥300℃. The measurement data of the force sensor can be used to calculate the in-situ measurement curve of the thermal weight loss of the drug strip.

[0017] Preferably, the heat conducting oil is selected from high-temperature-resistant modified silicon oil, and the heat-resistant temperature is ≥250℃. It is not easy to oxidize in an open heating environment for a long time, and it does not burn spontaneously at normal pressure.

[0018] Preferably, the infrared-transparent germanium glass box is made of heat-resistant infrared-transparent germanium glass, and the heat-resistant temperature is ≥500℃. The infrared-transparent germanium glass material is more conducive to high-speed infrared thermal imaging.

[0019] Preferably, the high-temperature-resistant quartz tube has a heat-resistant temperature of ≥1500℃. The actual measurement shows that the burning speed of the solid propellant drug strip in the quartz tube is fast, and the local burning time of the quartz tube is short. Such a quartz tube will not break when used to contain the drug strip for burning; the side surface of the high-temperature-resistant quartz tube is evenly marked with scale lines with a spacing of 1mm, which is convenient for use as a length scale when measuring the burning speed using infrared images.

[0020] Preferably, the laser is selected from a high-power CO2 laser, which is fixed on the support through a ball hinge. The non-contact ignition method of the laser does not damage the thermal damage microstructure of the high-initial-temperature drug strip, and does not affect the accuracy of the drug strip burning speed test. The laser is vertically installed above the high-temperature-resistant quartz tube for igniting the drug strip. The distance between the bottom end of the laser and the top end of the high-temperature-resistant quartz tube is greater than or equal to 50cm, so as to prevent the flame and high-temperature jet of the drug strip from burning the laser.

[0021] Preferably, the high-speed infrared thermal imager shoots the surface temperature distribution of the drug strip during the heating process through the infrared-transparent germanium glass box, records the infrared image for a long time at a frame rate of 1000fps, measures the burning speed of the thermal damage drug strip under the condition of high initial temperature in situ, and captures the surface temperature distribution and burning image of the drug strip during the thermal response process through the high-speed infrared thermal imager.

[0022] A solid propellant thermal weight loss and high-initial-temperature burning speed in-situ testing method based on the system comprises the following steps:

[0023] S1: The rubber ring is sleeved on the open end of the high-temperature-resistant quartz tube, and the counterweight of the rubber ring is adjusted to ensure that the high-temperature-resistant quartz tube does not float in the heat conducting oil when it is empty. The force sensor reading is F0 when it is empty.

[0024] S2: Adjust the focusing position of the laser, vertically align the center of the upper surface of the drug strip;

[0025] S3: Start the high-speed infrared thermal imager and the temperature rising program of the heating controller, monitor the thermocouple temperature and the surface temperature of the drug strip;

[0026] S4: Record the force sensor reading after the drug strip is placed in the heat-resistant quartz tube as F1, record the force sensor reading during the heating process as F2, and calculate the thermal weight loss rate δ of the drug strip by the following formula:

[0027]

[0028] S5: When the propellant reaches the expected high initial temperature thermal damage condition after program heating, start the laser to ignite the drug strip in situ;

[0029] S6: After the drug strip is burned out, the temperature rising program of the heating controller is turned off, the air cooling system is started to cool the heat conducting oil, and the new high-temperature-resistant quartz tube is replaced after the heat conducting oil is cooled;

[0030] S7: Calculate the high initial temperature drug strip burning rate using the infrared image of the drug strip burning taken by the high-speed infrared thermal imager, and output the weight loss rate-temperature curve and the high initial temperature drug strip burning rate-initial temperature curve after data processing.

[0031] Compared with the prior art, the present application provides a solid propellant thermal weight loss and high initial temperature burning rate in-situ testing system, which has the following beneficial effects:

[0032] The present application provides a solid propellant thermal weight loss and high initial temperature burning rate in-situ testing system, which improves and optimizes the structure of the existing solid propellant thermal decomposition and burning rate testing equipment, and can realize the in-situ testing of the high initial temperature drug strip burning rate of the solid propellant. It is very meaningful for the correlation between the thermal decomposition characteristics and the combustion performance of the solid propellant, the thermal safety and the baking combustion response research. The present application adjusts the heating temperature and duration of the solid propellant drug strip through the PID heating controller, tests the weight loss rate of the drug strip during the heating process through the high-precision force sensor, records the surface temperature distribution during the thermal response process of the drug strip through the high-speed thermal imager, and non-contact ignites the high initial temperature drug strip during heating through the laser and measures the high initial temperature drug strip burning rate in situ. In summary, the present application can realize the in-situ measurement of the high initial temperature drug strip burning rate, and the system has high visualization, can use the high-speed thermal imager to shoot the response process, the testing system can measure a variety of data in situ, has small overall size, is safe and reliable in work, and is easy to operate. BRIEF DESCRIPTION OF DRAWINGS

[0033] Fig. 1 is a front view of a solid propellant thermal weight loss and high initial temperature burning rate in-situ testing system mentioned in embodiment 1 of the present application;

[0034] Fig. 2 Figure 1 is a schematic diagram of the overall layout of a solid propellant thermal gravimetric and high initial temperature burning rate in-situ testing system mentioned in embodiment 1 of the present application;

[0035] Figure 1 is a schematic diagram of the overall layout of a solid propellant thermal gravimetric and high initial temperature burning rate in-situ testing system mentioned in embodiment 1 of the present application;

[0036] 1, laser; 2, bracket; 3, end cover; 4, clamp; 5, infrared germanium glass box; 6, heat conducting oil; 7, thermocouple; 8, U-shaped heating tube; 9, high-temperature-resistant quartz tube; 10, rubber ring; 11, force sensor; 12, propellant stick; 13, heating controller; 14, charge amplifier; 15, data acquisition card; 16, high-speed infrared thermal imager; 17, computer. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all.

[0038] The present application improves and optimizes the structure of the existing solid propellant thermal decomposition and burning rate testing equipment, and proposes a solid propellant thermal gravimetric and high initial temperature burning rate in-situ testing system. The heating temperature and duration of the solid propellant stick are adjusted by the PID heating controller, the weight loss rate of the propellant stick during heating is tested by the high-precision force sensor, the surface temperature distribution of the propellant stick during the thermal response process is recorded by the high-speed thermal imager, and the high initial temperature propellant stick during heating is non-contact ignited by the laser and the high initial temperature propellant stick burning rate is in-situ measured. The present application can realize in-situ measurement of the high initial temperature propellant stick burning rate, and the system has high visualization, can use the high-speed thermal imager to shoot the response process, the testing system can in-situ measure various data, has small overall size, is safe and reliable in work, and is easy to operate. Specifically, the following contents are included.

[0039] Embodiment 1

[0040] Please refer to Figs. 1-2 The present application proposes a solid propellant thermal gravimetric and high initial temperature burning rate in-situ testing system, which comprises a laser 1, a bracket 2, an end cover 3, a clamp 4, an infrared germanium glass box 5, heat conducting oil 6, a thermocouple 7, a U-shaped heating tube 8, a high-temperature-resistant quartz tube 9, a rubber ring 10, a force sensor 11, a propellant stick 12, a heating controller 13, a charge amplifier 14, a data acquisition card 15, a high-speed infrared thermal imager 16, and a computer 17. The laser 1 is used for igniting the propellant stick 12, is fixed on the crossbeam of the bracket 2 through a spherical hinge, and is suspended above the high-temperature-resistant quartz tube 9 and the propellant stick 12.

[0041] The bracket 2 is a truss structure, is clamped and fixed on the end cover 3 through the clamp 4, and is used for clamping the laser 1.

[0042] The end cover 3 is an upper cover of the infrared-transparent germanium glass box 5, and a through hole is formed on the surface of the end cover 3 for the U-shaped heating tube 8 and the high-temperature-resistant quartz tube 9 to pass through;

[0043] The infrared-transparent germanium glass box 5 is filled with heat-conducting oil 6, and the infrared-transparent germanium glass material is beneficial to the shooting of the high-speed infrared thermal imager 16;

[0044] The thermocouple 7 is fixedly connected with the U-shaped heating tube 8 and is immersed in the heat-conducting oil 6 to measure the oil temperature near the cigarette 12;

[0045] The U-shaped design of the U-shaped heating tube 8 is beneficial to uniformly heating the heat-conducting oil 6 through heat convection; the opening end of the high-temperature-resistant quartz tube 9 is clamped by the rubber ring 10 and is placed on the force sensor 11, the closed end is vertically immersed in the heat-conducting oil 6, and the cigarette 12 is placed in the high-temperature-resistant quartz tube 9;

[0046] The force sensor 11 has a ring structure, the through hole in the middle passes through the high-temperature-resistant quartz tube 9, and the whole is placed on the end cover 3; the heating controller 13 is connected with the two ends on the upper side of the U-shaped heating tube 8, and the U-shaped heating tube 8 is heated through the input signal of the thermocouple 7 and the PID control module;

[0047] The signal of the force sensor 11 is amplified by the charge amplifier 14 and is collected by the data acquisition card 15;

[0048] The high-speed infrared thermal imager 16 is erected in front of the infrared-transparent germanium glass box 5 to capture the surface temperature distribution and the combustion image of the cigarette 12 in the thermal response process;

[0049] The computer 17 is responsible for collecting the temperature measurement data from the heating controller 13, the force data from the data acquisition card 15, and the infrared image from the high-speed infrared thermal imager 16.

[0050] During the test, first, the rubber ring is sleeved on the opening end of the high-temperature-resistant quartz tube, the counterweight of the rubber ring is adjusted to ensure that the high-temperature-resistant quartz tube will not float in the heat-conducting oil when it is in an empty state, and the force sensor reading in the empty state is recorded as F0; then, the focusing position of the laser is adjusted, the vertical center of the upper surface of the cigarette is aligned, the temperature rising program of the high-speed infrared thermal imager and the heating controller is started, and the thermocouple temperature and the cigarette surface temperature are monitored; the force sensor reading after the cigarette is placed in the heat-resistant quartz tube is recorded as F1, the force sensor reading in the heating process is recorded as F2, then the thermal weight loss rate δ of the cigarette 12 is calculated based on F1 and F2, and the calculation formula is: When the propellant reaches the expected high initial temperature thermal damage condition after the programmed heating, the laser is started to ignite the grain in situ; after the grain is burned out, the heating controller is closed to start the air cooling system to cool the heat conducting oil, and after the heat conducting oil is cooled, the new high temperature resistant quartz tube is replaced; the infrared image of the grain burning is taken by the high speed infrared thermal imager, the high initial temperature grain burning rate is calculated, and the data is processed to output the weight loss rate-temperature curve and the high initial temperature grain burning rate-initial temperature curve in the grain heating process.

[0051] In summary, the solid propellant thermal weight loss and high initial temperature burning rate in-situ testing system proposed by the present application can carry out the thermal decomposition characteristics and the burning rate in-situ testing of the damaged propellant, and can monitor the thermal weight loss rate and the thermal conduction temperature field in the testing of the thermal decomposition and thermal damage characteristics of the propellant, and can test the burning rate characteristics and the burning temperature field of the high initial temperature grain in the combustion performance. The heating temperature and time of the solid propellant grain are adjusted by the PID heating controller, the weight loss rate of the grain in the heating process is tested by the high precision force sensor, the surface temperature distribution in the thermal response process of the grain is recorded by the high speed thermal imager, the high initial temperature grain in the heating process is ignited by the laser, and the high initial temperature grain burning rate is measured in situ.

[0052] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A solid propellant thermal gravimetric and high initial temperature burning rate in-situ testing system, characterized in that, The test system comprises a test mechanism, a heating controller (13), a charge amplifier (14), a data acquisition card (15), a high-speed infrared thermal imager (16) and a computer (17); The heating controller (13) is matched with the test mechanism to control and record the heating temperature of the test mechanism. The charge amplifier (14) is used to amplify the signal generated by the test mechanism. The data acquisition card (15) is used to collect the signal amplified by the charge amplifier (14). The high-speed infrared thermal imager (16) is used to shoot and monitor the image data in the test process of the test mechanism. The computer (17) is used to collect the temperature data from the heating controller (13), the signal data from the data acquisition card (15) and the image data from the high-speed infrared thermal imager (16). The test mechanism comprises a laser (1), a support (2), an end cover (3), a clamp (4), an infrared-transparent germanium glass box (5), heat-conducting oil (6), a thermocouple (7), a U-shaped heating pipe (8), a high-temperature-resistant quartz tube (9), a rubber ring (10), a force sensor (11) and a medicine stick (12); the heat-conducting oil (6) is contained in the infrared-transparent germanium glass box (5), the end cover (3) is fixed on the top of the infrared-transparent germanium glass box (5), the force sensor (11) is fixedly installed at the center of the top surface of the end cover (3), the high-temperature-resistant quartz tube (9) is clamped and connected to the rubber ring (10), and the rubber ring (10) is placed on the force sensor (11); the rubber ring (10) is designed in a ring shape, through holes are arranged at the center of the rubber ring (10) and the end cover (3), the high-temperature-resistant quartz tube (9) penetrates through the through holes and is placed in the heat-conducting oil (6), and the medicine stick (12) is arranged in the high-temperature-resistant quartz tube (9); the U-shaped heating pipe (8) is connected to the end cover (3), and the thermocouple (7) is integrally installed in the U-shaped heating pipe (8); the support (2) is a truss structure, is clamped and fixed to the end cover (3) through the clamp (4), and the laser (1) is fixedly connected to the top of the support (2).

2. The solid propellant thermal gravimetric and high initial temperature burning rate in-situ test system according to claim 1, characterized in that, The heating controller (13) is connected to the two ends of the upper side of the U-shaped heating pipe (8) to control the heating of the U-shaped heating pipe (8) through the input signal of the thermocouple (7) and a PID control module.

3. The solid propellant thermal gravimetric and high initial temperature burning rate in-situ test system according to claim 1, characterized in that, The charge amplifier (14) is used to amplify the signal collected by the force sensor (14), and the force sensor (14) is selected from high-precision high-temperature-resistant sensors with a maximum working temperature of ≥300℃.

4. The solid propellant thermal gravimetric and high initial temperature burning rate in-situ test system of claim 1, wherein, The heat-conducting oil (6) is selected from high-temperature-resistant modified silicon oil with a heat-resistant temperature of ≥250℃.

5. The solid propellant thermal gravimetric and high initial temperature burning rate in-situ test system of claim 1, wherein, The infrared-transparent germanium glass box (5) is made of heat-resistant infrared-transparent germanium glass with a heat-resistant temperature of ≥500℃.

6. The solid propellant thermal gravimetric and high initial temperature burning rate in-situ test system of claim 1, wherein, The high-temperature-resistant quartz tube (9) has a heat-resistant temperature of ≥1500℃, and the side surface of the high-temperature-resistant quartz tube (9) is evenly marked with scale lines with an interval of 1 mm.

7. The solid propellant thermal gravimetric and high initial temperature burning rate in-situ test system of claim 1, wherein, The laser (1) is selected from high-power CO2 laser, which is fixed on the support (2) through ball hinge; the laser (1) is vertically installed above the high-temperature-resistant quartz tube (9) to ignite the drug rod (12), and the distance between the bottom end of the laser (1) and the top end of the high-temperature-resistant quartz tube (9) is greater than or equal to 50 cm.

8. The solid propellant thermal gravimetric and high initial temperature burning rate in-situ test system of claim 1, wherein, The high-speed infrared thermal imager (16) shoots the surface temperature distribution of the drug rod (12) in the heating process through the infrared-transparent germanium glass box (5), records the infrared image for a long time at a frame rate of 1000 fps, and measures the burning rate of the heat-damaged drug rod under the high initial temperature condition in situ.

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