Device for measuring high-pressure combustion temperature of solid propellant

Abstract

The invention relates to the technical field of solid propellant combustion performance testing, and particularly discloses a solid propellant high-pressure combustion temperature measuring device which comprises a top cover, a bottom cover, a shell, a top cover binding post, a bottom cover binding post and a thermocouple. The shell is cylindrical; the top cover and the bottom cover are partially embedded into the two ends of the shell respectively; the top cover is in opening and closing connection with the shell; when the top cover is closed, a closed space among the shell, the top cover and the bottom cover is a combustion cavity; one end of the top cover binding post is connected with the pressurizing powder through the ignition wire, and the other end penetrates through the top cover to be connected with an external power supply; one end of the bottom cover binding post is connected with the test medicine strip through a thermocouple, and the other end penetrates through the bottom cover to be connected with the test system; when the pressurizing powder is communicated with an external power supply, the pressurizing powder burns, the temperature in the combustion cavity rises, the test powder strip is ignited, and the test system obtains the potential difference of the thermocouple, converts the potential difference into combustion temperature and sends the combustion temperature to the processor; the processor carries out synchronous recording according to the received combustion temperature and the pressure intensity sent by the pressure intensity sensor.

Description

Technical Field

[0001] The invention relates to the technical field of solid propellant combustion performance testing, and in particular to a solid propellant high-pressure combustion temperature measuring device. Background Art

[0002] The combustion of solid propellants is a physical and chemical process with intense light and heat generation. The constant-pressure combustion temperature of solid propellants is an important energy parameter. By accurately determining the combustion temperature of solid propellants, data can be provided for the study of the combustion mechanism of propellants and the establishment of combustion models, as well as for the selection and strength calculation of engine casing materials and the prediction of propellant energy characteristics.

[0003] The propellant combustion temperature test methods mainly include contact method and non-contact method. Among the contact methods, there is a thermocouple method, which uses the principle that different metals have different electron movement rates at the same temperature. Different electron movement rates will produce a potential difference, and the temperature of the point can be obtained by measuring the potential difference. The thermoelectric potential at both ends of the thermocouple is at the mV level, which may be affected by the ignition voltage and current of the propellant strip. However, as a mature temperature measurement method, the thermocouple method has the advantages of direct testing and low testing cost, and the experimental results are reproducible. It has been widely used in engineering practice.

[0004] At present, conventional solid propellant combustion temperature test systems such as Figure 1 As shown, it consists of five parts: high-pressure gas cylinder, burner, buffer bottle, exhaust pipeline, ignition power supply and data acquisition system. The constant-pressure combustion temperature of solid propellant must be tested under a specific pressure to be meaningful. The high-pressure gas cylinder is used for pressurization before the experiment, and the buffer bottle is used to maintain a constant pressure environment during the experiment. The ignition power supply provides the ignition voltage at the beginning of the experiment, and the acquisition system is used for real-time pressure and temperature collection and transmission. The two are connected to the burner base. The exhaust pipeline is used to discharge exhaust gas after the experiment. However, the existing solid propellant combustion temperature test system has the following two problems:

[0005] 1) Some propellant combustion experiments need to be carried out under high pressure, which will exceed the maximum pressure provided by standard high-pressure gas cylinders. The air tightness of the valve pipeline and the pressure resistance of the gas storage cylinder cannot meet the requirements of this part of the high-pressure experiment.

[0006] 2) The thermoelectric potential at both ends of the thermocouple is at the mV level. Since the ignition wire and the thermocouple wire are connected to the test medicine strip at the same time, the ignition voltage will interfere with the electromotive force generated by the thermocouple, which is manifested as the room temperature of the same group of experiments remains basically unchanged, but the initial temperature of the test changes. Summary of the invention

[0007] In view of the above problems, the purpose of the present invention is to provide a solid propellant high-pressure combustion temperature measuring device, which can achieve self-pressurization during the temperature measurement process, improve the measurement accuracy of the thermocouple method, and reduce the measurement cost.

[0008] The present invention provides a solid propellant high-pressure combustion temperature measuring device, comprising: a top cover, a bottom cover, a shell, a top cover terminal, a bottom cover terminal, and a thermocouple;

[0009] The shell is cylindrical; the top cover and the bottom cover are partially embedded in the two ends of the shell respectively; the top cover is connected to the shell in an opening and closing manner; when the top cover is closed, the enclosed space between the shell, the top cover and the bottom cover is a combustion chamber;

[0010] One end of the top cover terminal is connected to the pressurizing agent through an ignition wire, and the other end passes through the top cover to be connected to an external power source;

[0011] One end of the bottom cover terminal is connected to the test medicine strip via a thermocouple, and the other end passes through the bottom cover to be connected to the test system;

[0012] When the pressurizing agent is connected to an external power supply, the pressurizing agent burns, the temperature in the combustion chamber rises, and the test medicine strip is ignited. The test system obtains the potential difference of the thermocouple, converts the potential difference into a combustion temperature, and sends it to the processor; the processor synchronously records the received combustion temperature and the pressure sent by the pressure sensor.

[0013] In a possible implementation, a protective sleeve is further included; the protective sleeve is sleeved on the thermocouple to protect the thermocouple.

[0014] In a possible implementation, an exhaust valve is further included; the exhaust valve is arranged on the bottom cover and is used to exhaust the exhaust gas from the combustion chamber.

[0015] In a possible implementation, a handle is further provided on the top cover to facilitate opening and closing of the top cover.

[0016] In a possible implementation, the thermocouple is a tungsten-rhenium thermocouple wire.

[0017] In a possible implementation, one end of the tungsten-rhenium thermocouple wire is embedded in the test medicine strip.

[0018] In a possible implementation, the outer surface of the test drug strip is coated with a coating liquid for flame retardancy.

[0019] In a possible implementation, the pressurizing drug is fixed on the top cover, and the test drug strip is fixed on the bottom cover.

[0020] The present invention provides a solid propellant high-pressure combustion temperature measuring device, which changes the pressurization method in the existing solid propellant temperature measurement experiment, can achieve high pressure that cannot be provided by gas cylinder pressurization, meet the needs of propellant high-pressure combustion temperature test, and solve the problem of being limited by the maximum pressure of the gas cylinder; optimize the gas cylinder and pipeline required in the traditional temperature measurement experiment, realize the miniaturization of the device, and reduce the experimental cost; by changing the ignition method, the ignition wire in the test medicine strip is cancelled, and the ignition is connected to the top cover, and the thermocouple temperature measurement is connected through the base, which avoids the influence of the ignition voltage on the thermocouple measurement result, and improves the measurement accuracy of the thermocouple method. The solid propellant high-pressure combustion temperature measuring device of the present invention can measure the constant-pressure combustion temperature of the solid propellant under high pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of an existing solid propellant temperature measurement device;

[0022] Figure 2 A schematic cross-sectional view of a solid propellant temperature measurement device provided in an embodiment of the present invention;

[0023] Figure 3 A schematic top view of a solid propellant temperature measurement device provided in an embodiment of the present invention;

[0024] Figure 4 A comparison diagram of the pressure change in the device with and without the test strip provided by the embodiment of the present invention;

[0025] Figure 5 A schematic diagram of the combustion temperature test results of a low-temperature propellant provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following detailed description of the embodiments of the present invention is further described in detail in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the preferred embodiments described, and the scope of the present invention is defined by the claims.

[0027] In the description of the present invention, it should be noted that, unless otherwise specified, “plurality” means two or more than two; the terms “first”, “second”, etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; for ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0028] Figure 2 A schematic cross-sectional view of a solid propellant temperature measuring device provided in an embodiment of the present invention, Figure 3 A schematic top view of a solid propellant temperature measuring device provided in an embodiment of the present invention, combined with Figure 2and Figure 3 , the present invention provides a solid propellant high-pressure combustion temperature measuring device, comprising: a top cover 1, a bottom cover 2, a shell 3, a top cover terminal 4, a bottom cover terminal 5, and a thermocouple;

[0029] The shell 3 is cylindrical; the top cover 1 and the bottom cover 2 are partially embedded in the two ends of the shell 3 respectively; the top cover 1 is connected with the shell 3 in an opening and closing manner; when the top cover 1 is closed, the enclosed space between the shell 3, the top cover 1 and the bottom cover 2 is a combustion chamber;

[0030] One end of the top cover terminal 4 is connected to the pressurized medicine through the ignition wire, and the other end passes through the top cover 1 to be connected to the external power supply;

[0031] One end of the bottom cover terminal 5 is connected to the test medicine strip through a thermocouple, and the other end passes through the bottom cover 2 and is connected to the test system;

[0032] When the pressurizing charge is connected to an external power source, the pressurizing charge burns, the temperature in the combustion chamber rises, the test charge strip is ignited, and the test system obtains the potential difference of the thermocouple, converts the potential difference into combustion temperature, and sends it to the processor; the processor synchronously records the received combustion temperature and the pressure sent by the pressure sensor.

[0033] In a possible implementation, a protective sleeve is further included; the protective sleeve is arranged on the thermocouple to protect the thermocouple. The protective sleeve can also insulate the thermocouple from the metal base to ensure that the potential difference generated by the thermocouple can be collected.

[0034] In a possible implementation, an exhaust valve is also included; the exhaust valve is arranged on the bottom cover 2 and is used to discharge the exhaust gas from the combustion chamber.

[0035] In a possible implementation, a handle is further provided on the top cover 1 to facilitate opening and closing of the top cover 1 .

[0036] In a possible implementation, to ensure the rapid response of the thermocouple, the thermocouple wire diameter should be as thin as possible. Considering the high combustion temperature of the solid propellant, the thermocouple is a tungsten-rhenium thermocouple wire. The tungsten-rhenium thermocouple wire is welded by direct current arc welding in an argon environment, and the welding quality is confirmed under a magnifying glass.

[0037] The principle of thermocouple temperature measurement is that two different thermocouple wires generate different voltages at the same temperature, and the temperature of the point can be determined by measuring the potential difference.

[0038] In one possible implementation, one end of a tungsten-rhenium thermocouple wire is embedded in a test strip.

[0039] In one possible implementation, since the combustion of the pressurized charge will cause the temperature of the entire system to rise, in order to prevent the thermocouple wire from melting, the thermocouple wire must be coated after it is connected. The outer surface of the test strip is coated with a coating liquid for side flame retardancy to achieve one-dimensional combustion of the propellant vertical end surface.

[0040] In a possible implementation, the pressurizing agent is fixed at the top cover 1 and the test agent strip is fixed at the bottom cover 2 to avoid the influence of the ignition voltage and current on the thermocouple response voltage.

[0041] Through the self-pressurizing solid propellant measuring device described above, the present invention can realize the accurate measurement of the constant-pressure combustion temperature of different types of solid propellants at different pressures.

[0042] The specific experimental process is as follows:

[0043] 1) Cut the test strip in half with a sharp blade, and place the thermocouple wire at the end of the cut, directly in contact with the uncut propellant. Tie the cut part tightly with external force (cotton thread) to restore the appearance of the test strip to its original integrity. Apply a coating liquid flame retardant on the outer surface of the test strip.

[0044] 2) Fix the pressurizing agent and the ignition wire on the top cover of the high-pressure burner, fix the propellant test strip on the base of the burner, and connect the terminal on the base to the two poles of the thermocouple.

[0045] 3) The temperature distribution of the propellant combustion process can be measured upon ignition.

[0046] In a preferred embodiment, the maximum pressures of the two groups containing pressor only and the pressor and test strips are approximately equal.

[0047] In a preferred embodiment, in a test group containing both pressurized medicine and test medicine strips, since the heat generated by the combustion of the test medicine strips and the heat loss of the fuel gas and the burner offset each other, a pressure plateau period can be achieved for a period of time during the combustion process.

[0048] In a preferred embodiment, the coated cylindrical test strip is end-face burned along the uncoated surface during the test, the burning time is about 1 s, and the temperature test time is about 0.1 s.

[0049] In a preferred embodiment, the solid propellant is fixed on the base by connecting the thermocouple wire to the terminal, and the uncoated surface faces the pressurizing charge side.

[0050] In a preferred embodiment, the ignition of the pressurized charge is achieved by heating the ignition wire through an ignition power supply, and the ignition of the test powder strip is achieved by the combustion of the pressurized charge to increase the temperature of the entire burner.

[0051] Pressure is related to the amount of pressor, which is given by the following formula: PV = nRT

[0052] Wherein, P is the expected pressure, Pa; V is the volume of the combustion chamber, m3; n is the number of moles of gas produced by combustion calculated based on the number of moles and mass of the fuel gas of the pressurizing agent, mol; T is the temperature of the gas produced by the combustion of the pressurizing agent, K.

[0053] The amount of pressor to be used can be calculated based on the expected pressure.

[0054] Furthermore, when the error between the measured pressure value and the theoretical pressure is greater than 5%, the data set is considered to be an abnormal value and is eliminated.

[0055] The following are examples of temperature measurements of two different test strips.

[0056] Example 1

[0057] The test strips were made of standard SQ-2 propellant samples, and the pressurizing agent was made of crumb SQ-2 propellant with a particle size of less than 0.1g. The thermocouple was embedded in the test strips, and the pressurizing agent was ignited after the various parts of the device were assembled. The combustion of the pressurizing agent increased the system temperature and ignited the test strips. During the experiment, the pressure and temperature were measured.

[0058] Figure 4 A comparison diagram of the pressure change in the device with and without the test strip provided by the embodiment of the present invention, such as Figure 4 As shown, due to the small particle size of the pressurizing agent, it burns very quickly, so the first pressure peak comes from the complete combustion of the pressurizing agent. At the same time, the system temperature rises and the test medicine strip is ignited. Due to the influence of the side coating, the combustion of the test medicine strip advances in the direction perpendicular to the end face (one-dimensional). At this time, the heat released by the combustion of the test medicine strip and the heat dissipated by the system to the external environment reach a state of equilibrium. Therefore, the combustion of the test medicine strip can achieve a pressure plateau period in a relatively short period of time during thermocouple temperature measurement, and the measured temperature can be considered as the combustion temperature under a specific pressure. The second pressure peak represents the end of the combustion of the test medicine strip and the rapid drop in the system temperature.

[0059] Comparison of the two sets of pressure curves shows that the burning speed of the pressurized charge is much faster than that of the test charge. The test charge starts to burn after the pressurized charge is completely burned, and the burning time is longer than that of the pressurized charge.

[0060] From the temperature measurement curve, it can be seen that during the combustion of the test cartridge, the temperature first rises rapidly to reach the first peak value, at which the temperature is about 800°C. Then the temperature fluctuates around the first peak value for about 0.1s. Then the temperature continues to rise and reaches the second peak value of 1763.4°C. At this time, the temperature reaches the maximum and the plateau pressure is 14.5±0.3MPa. Then the temperature drops rapidly and the pressure plateau continues to be maintained for about 0.4s. The plateau time is far beyond the thermocouple temperature measurement time. Therefore, the test results can be regarded as the constant-pressure combustion temperature under this pressure.

[0061] Example 2

[0062] The test strips selected low-temperature composite propellants with the chemical formula: C17.413H54.322O24.431N15.111Fe0.068Cl3.660, and the pressurizing agent selected double-base propellant standard SQ-2 propellant debris, and the amount of pressurizing agent was 5g. In order to ensure that the high temperature after the pressurizing agent burns will not cause the thermocouple wire to melt, the thermocouple wire must be coated and ignited to build pressure.

[0063] Figure 5 A schematic diagram of the combustion temperature test results of a low-temperature propellant provided in an embodiment of the present invention is shown in FIG. Figure 5 As shown, the pressurizing agent burns rapidly and establishes the first pressure peak. The low-temperature propellant strip has a slow burning rate, a small number of moles of fuel gas, and a downward trend in the overall system temperature, so the overall system pressure decreases. Since the thermocouple wire welding point is in the middle of the test strip, the temperature measurement time point is not at the pressure peak, but at the pressure stable section, and the propellant combustion temperature test must also be carried out under the condition of stable section pressure.

[0064] In order to ensure the constancy of pressure in a short period of time during the combustion temperature test, the length and end surface area of ​​the test strips need to be adjusted according to the different burning rates of different types of test strips.

[0065] In this embodiment, the pressurizing agent and the test medicine strip are of different types. The functions of the pressurizing agent are: 1. Consume oxygen in the burner to ensure that the test medicine strip burns under oxygen-free conditions. 2. Increase the system temperature to ignite the test medicine strip. 3. Rapidly establish high pressure to provide the high-pressure environment required for measuring the combustion temperature of the test medicine strip. Therefore, the pressurizing agent only needs to be a propellant that meets the above three points, and does not need to be the same type as the test medicine strip.

[0066] In this embodiment, the plateau pressure is 7.53±0.5MPa, and the measured result can be regarded as the constant pressure combustion temperature under this pressure. The combustion temperature rises rapidly, and the temperature peak is 1222.8℃ and remains for a long time. Therefore, it is believed that the constant pressure combustion temperature of this type of propellant at 7.5MPa is 1222.8℃.

[0067] The solid propellant high-pressure combustion temperature measuring device provided by the present invention can reduce external gas sources and pipeline valves, and use a pressurizing agent to quickly establish high pressure. The pressurizing agent can be selected from a standard low-temperature propellant with a high gasification rate and no aluminum, or can be selected from the same pellets as the test medicine strip. The number of moles of gas generated by the combustion of the pressurizing agent directly determines the experimental pressure. Therefore, by changing the type and quality of the pressurizing agent, the experimental pressure can be adjusted so that the combustion of the test medicine strip maintains high pressure; the temperature of the burning test medicine strip is measured using a thermocouple. The test medicine strip must be coated to ensure end face combustion. By adjusting the cross-sectional area of ​​the test medicine strip, a pressure plateau period within a shorter period of time of thermocouple temperature measurement can be achieved. Therefore, the measurement result of the device can be regarded as the constant-pressure combustion temperature of the solid propellant.

[0068] Compared with the existing solid propellant combustion temperature measurement device, the improvements of this device include:

[0069] 1. Self-pressurization can be achieved through the combustion of the pressurizing agent, and the pressure plateau period can be achieved in a short time by adjusting the burning surface area of ​​the test strip, ensuring a constant pressure environment during the temperature measurement period.

[0070] 2. The pressure of the pressure plateau established in the experiment is related to the gas formation rate of the pressurizing agent. Therefore, choosing a pressurizing agent with a high gas formation rate can achieve high pressure that cannot be achieved by external gas source pressurization.

[0071] 3. Since the principle of thermocouple temperature measurement is to measure the potential difference, when the thermocouple and the ignition wire are connected to the test medicine strip at the same time, they are easily affected by the ignition voltage. In this device, the test medicine strip is ignited by the combustion of the pressurized medicine, which can eliminate the influence of the ignition wire on the thermocouple temperature measurement.

[0072] 4. The experimental device has a simple structure and reduces the use of gas cylinders and pipelines compared to the solid propellant combustion temperature measurement device. The use and maintenance costs are low.

[0073] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A solid propellant high pressure combustion temperature measuring device, characterized in that: include: Top cover, bottom cover, shell, top cover terminal, bottom cover terminal, thermocouple; The shell is cylindrical; the top cover and the bottom cover are partially embedded in the two ends of the shell respectively; the top cover is connected to the shell in an opening and closing manner; when the top cover is closed, the enclosed space between the shell, the top cover and the bottom cover is a combustion chamber; One end of the top cover terminal is connected to the pressurizing agent through an ignition wire, and the other end passes through the top cover to be connected to an external power source; One end of the bottom cover terminal is connected to the test medicine strip via a thermocouple, and the other end passes through the bottom cover to be connected to the test system; When the pressurizing agent is connected to an external power supply, the pressurizing agent burns, the temperature in the combustion chamber rises, and the test medicine strip is ignited. The test system obtains the potential difference of the thermocouple, converts the potential difference into a combustion temperature, and sends it to the processor; the processor synchronously records the received combustion temperature and the pressure sent by the pressure sensor.

2. The solid propellant high-pressure combustion temperature measuring device according to claim 1, characterized in that: It also includes a protective sleeve, which is sleeved on the thermocouple to protect the thermocouple.

3. The solid propellant high-pressure combustion temperature measuring device according to claim 1, characterized in that: It also includes an exhaust valve; the exhaust valve is arranged on the bottom cover and is used to exhaust the exhaust gas from the combustion chamber.

4. The solid propellant high-pressure combustion temperature measuring device according to claim 1, characterized in that: The top cover is also provided with a handle to facilitate the opening and closing of the top cover.

5. The solid propellant high-pressure combustion temperature measuring device according to claim 1, characterized in that: The thermocouple is a tungsten-rhenium thermocouple wire.

6. The solid propellant high-pressure combustion temperature measuring device according to claim 5, characterized in that: One end of the tungsten-rhenium thermocouple wire is embedded in the test medicine strip.

7. The solid propellant high-pressure combustion temperature measuring device according to claim 1, characterized in that: The outer surface of the test medicine strip is coated with a coating liquid for flame retardancy.

8. The solid propellant high-pressure combustion temperature measuring device according to claim 1, characterized in that: The pressurizing medicine is fixed at the top cover, and the test medicine strip is fixed at the bottom cover.

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