Device and method for measuring erosion combustion rate of solid propellant

Abstract

The invention relates to a device and a method for measuring the erosion combustion rate of a solid propellant, and belongs to the technical field of mechanical design and measurement. According to the device, fuel gas is generated through charging of a combustion chamber, the real working condition of an engine is simulated, a set of test piece clamps and test pieces are placed in a low-speed section, a convergence section and a high-speed section respectively, and the erosion combustion rates under three flow rates can be obtained at the same time and multiple sets of data can be obtained by measuring the thicknesses of the propellant test pieces. During testing, combustion chamber charge is ignited, the residual thickness of the propellant test piece is measured after combustion of the combustion chamber charge is finished, the combustion thickness is calculated, the gas flow rates of a low-speed section, a convergence section and a high-speed section are calculated, and the erosion combustion rates of the propellant at the three flow rates are obtained. And according to an erosion combustion theory, an erosion combustion rate formula of the propellant at different flow rates can be deduced. The measuring device is simple in structure and high in reliability, simulation of the real working condition of the solid engine can be achieved, and the measuring result has higher engineering application value.

Description

Technical Field

[0001] This invention belongs to the field of mechanical design and measurement technology, specifically relating to a device and method for measuring the erosion and combustion rate of solid propellants. Background Technology

[0002] When solid propellant burns in the combustion chamber, the resulting high-temperature combustion gases flow at high speed parallel to the propellant's combustion surface. The combustion rate of the propellant changes due to velocity coupling effects; this phenomenon is called erosion combustion. Currently, many solid rocket motor propellant grains employ an internal combustion profile. To increase propellant packing density, the ratio of the initial channel area of ​​the central hole in the propellant grain to the area of ​​the nozzle throat is relatively small. This results in a high gas velocity at the rear end of the propellant grain during the initial stage of engine operation, increasing the propellant's burning rate. For complex propellant grains, localized erosion combustion may also occur due to localized high velocities. Erosion combustion significantly affects the change in combustion chamber pressure over time, thus impacting engine performance. If the effects of erosion combustion are not considered in engine design, it can alter the expected thrust variation, or even lead to premature exposure of the casing to hot gas flow, resulting in structural failure. Therefore, erosion combustion is a crucial topic in solid rocket motor research.

[0003] Because the interaction and mutual influence between propellant and combustion gas flow are highly complex, elucidating the erosion combustion mechanism is extremely difficult. Deriving theoretical or empirical formulas based on experimental results is currently the most important research method. However, due to the harsh environment of high temperature and high pressure within the combustion chamber, the methods for testing erosion combustion rates are extremely limited, mainly including the combustion termination method and high-speed photography. The combustion termination method can simulate real-world conditions, but only one set of data can be obtained per experiment, resulting in high experimental costs. High-speed photography offers the advantage of continuous measurement, but the experimental equipment is complex, and the experimental conditions differ from real-world conditions. Therefore, there is an urgent need to design more efficient and accurate methods for measuring erosion combustion rates to support related theoretical research and engineering applications. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned defects of the prior art and provide a device and method for measuring the erosion and combustion rate of solid propellants. Under the condition of simulating the real working conditions of solid propellant engines, multiple sets of measurement data can be obtained at one time, providing support for the theoretical research and engineering application of erosion and combustion problems.

[0005] The above-mentioned objectives of the present invention are mainly achieved through the following technical solutions:

[0006] A solid propellant erosion combustion rate measuring device includes a front end cap, a combustion chamber shell, a low-velocity section specimen holder, a low-velocity section specimen, a convergent section shell, a convergent section specimen holder, a convergent section specimen, a convergent section bushing, a high-velocity section shell, a high-velocity section bushing, a high-velocity section specimen holder, a high-velocity section specimen, a nozzle shell, a throat liner, and a propellant charge. The front end cap, combustion chamber shell, convergent section shell, high-velocity section shell, and nozzle shell are sequentially connected to form a cylindrical body. The low-velocity section specimen holder is fixed to the inner surface of the combustion chamber shell. The low-velocity section specimen passes through a low-velocity section... The low-speed section specimen is fixed by a clamp, and the convergent section specimen is fixed inside the convergent section shell. The convergent section specimen is fixed by the convergent section specimen clamp. The convergent section bushing is set on the inner surface of the convergent section shell, with one end in contact with the convergent section specimen clamp and the convergent section specimen, and the other end in contact with the high-speed section bushing. The high-speed section specimen clamp is connected to the high-speed section shell, and the high-speed section specimen is fixed by the high-speed section specimen clamp. The throat liner is set on the inner surface of the nozzle shell, and the propellant is set at the bottom of the combustion chamber shell. The low-speed section specimen, the convergent section specimen, and the high-speed section specimen are propellant specimens.

[0007] It also includes a sealing plug and a pressure cap. The combustion chamber shell is provided with a pressure measuring hole and a suffocation device interface. A pressure sensor is connected through the pressure measuring hole, and a suffocation device is connected through the suffocation device interface. The pressure measuring hole and the suffocation device interface are sealed by the sealing plug and the pressure cap.

[0008] It also includes fixing bolts, flat washers, spring washers, fixing nuts, and sealing rings. The front end cap, combustion chamber housing, convergent section housing, high-speed section housing, and nozzle housing are all connected by fixing bolts, flat washers, spring washers, and fixing nuts, and the connection is sealed by sealing rings.

[0009] The low-speed section specimen clamp, the convergence section specimen clamp, and the high-speed section specimen clamp are each provided with a plurality of T-slots, and a plurality of low-speed section specimens, a plurality of convergence section specimens, and a plurality of high-speed section specimens are fixed through the T-slots.

[0010] It includes 8 low-speed segment specimens, which are evenly distributed circumferentially; 8 convergence segment specimens, which are evenly distributed circumferentially; and 4 high-speed segment specimens, which are evenly distributed circumferentially.

[0011] The front end cap, combustion chamber shell, low-speed section specimen clamp, convergence section shell, convergence section specimen clamp, convergence section bushing, high-speed section shell, high-speed section bushing, high-speed section specimen clamp, and nozzle shell are made of 30CrMnSi, with a pressure range of 2 to 20 MPa and a maximum working time of 10 seconds.

[0012] The low-speed section specimen clamp is located at one end of the combustion chamber shell connecting to the convergent section shell, and the convergent section specimen clamp is located in the middle of the convergent section shell, achieving a smooth transition of the inner surface through the convergent section bushing; the high-speed section specimen clamp is located in the middle of the high-speed section shell, achieving a smooth transition of the inner surface through the high-speed section bushing.

[0013] The same propellant was used for the propellant charge, low-speed section test specimen, convergence section test specimen, and high-speed section test specimen.

[0014] The combustion time of the propellant is shorter than that of the low-speed section specimen, the convergence section specimen, or the high-speed section specimen.

[0015] A method for measuring the erosion and burning rate of solid propellants, using the aforementioned measuring device, specifically includes the following steps:

[0016] (1) Ignite the charge and record the combustion chamber pressure;

[0017] (2) After the explosive is burned out, flush and discharge the gas in the experimental device;

[0018] (3) Take out and measure the remaining wall thickness of the low-speed section specimen, the convergence section specimen and the high-speed section specimen, and subtract the initial wall thickness to obtain the combustion wall thickness;

[0019] (4) Calculate the gas flow velocities in the low-speed section, convergence section, and high-speed section;

[0020] (5) Based on the combustion thickness of the specimen under different gas flow rates, the formula for the propellant erosion combustion rate is obtained.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] (1) The measuring device of the present invention can simulate the real working conditions of solid rocket motors, including pressure, flow rate, and gas properties, and the measurement results have stronger engineering application significance.

[0023] (2) The measuring device of the present invention can obtain multiple sets of data at three flow rates at one time. Compared with the traditional asphyxiation test engine, which can only measure one set of data at one time, the experimental efficiency is greatly improved and the experimental cost is greatly reduced.

[0024] (3) The measuring device of the present invention has a simple and reliable mechanical structure, low cost, and is easy to maintain and replace parts. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the solid propellant erosion and combustion rate measuring device of the present invention;

[0026] Figure 2 This is a schematic diagram of the test stand for the solid propellant erosion and combustion rate measuring device of the present invention. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments:

[0028] like Figure 1As shown, a solid propellant erosion combustion rate measuring device includes a front end cap 1, a combustion chamber shell 2, a low-velocity section specimen clamp 5, a low-velocity section specimen 6, a convergent section shell 7, a convergent section specimen clamp 8, a convergent section specimen 9, a convergent section bushing 10, a high-velocity section shell 11, a high-velocity section bushing 12, a high-velocity section specimen clamp 13, a high-velocity section specimen 14, a nozzle shell 15, a graphite throat liner 16, and a propellant charge 22. The front end cap 1, combustion chamber shell 2, convergent section shell 7, high-velocity section shell 11, and nozzle shell 15 are sequentially connected to form a cylindrical body. The low-velocity section specimen clamp 5 is fixed in the combustion chamber. On the inner surface of the housing 2, the low-speed section specimen 6 is fixed by the low-speed section specimen clamp 5, the convergent section specimen clamp 8 is fixed inside the convergent section housing 7, the convergent section specimen 9 is fixed by the convergent section specimen clamp 8, the convergent section bushing 10 is set on the inner surface of the convergent section housing 7, one end is in contact with the convergent section specimen clamp 8 and the convergent section specimen 9, and the other end is in contact with the high-speed section bushing 12, the high-speed section specimen clamp 13 is connected to the high-speed section housing 11, the high-speed section specimen 14 is fixed by the high-speed section specimen clamp 13, the graphite throat liner 16 is set on the inner surface of the nozzle housing 15, and the charge 22 is set at the bottom of the combustion chamber housing 2.

[0029] It also includes a sealing plug 3 and a pressure cap 4. The combustion chamber shell 2 has a pressure measuring hole and a suffocation device interface. A pressure sensor is connected through the pressure measuring hole, and a suffocation device is connected through the suffocation device interface. Both the pressure measuring hole and the suffocation device interface are sealed by the sealing plug 3 and the pressure cap 4. The suffocation device consists of a high-pressure nitrogen cylinder and an electronic valve.

[0030] It also includes fixing bolts 17, flat washers 18, spring washers 19, fixing nuts 20 and sealing rings 21. The front end cap 1, combustion chamber housing 2, convergent section housing 7, high-speed section housing 11 and nozzle housing 15 are all connected by fixing bolts 17, flat washers 18, spring washers 19 and fixing nuts 20, and the connection is sealed by sealing rings 21.

[0031] like Figure 2 As shown, the solid propellant erosion and combustion measurement device frame includes a baffle 23, a bracket 24, a platform 25, a front clamp 26, a front support 27, a rear clamp 28, and a rear support 29.

[0032] The main structure, including the front end cap 1, combustion chamber shell 2, pressure cap 4, low-speed section specimen clamp 5, convergent section shell 7, convergent section specimen clamp 8, convergent section bushing 10, high-speed section shell 11, high-speed section bushing 12, high-speed section specimen clamp 13, and nozzle shell 15, is made of 30CrMnSi material, with a designed pressure range of 2-20MPa and a maximum working time of 10s.

[0033] It includes 8 low-speed segment specimens 6, which are evenly distributed circumferentially; 8 convergence segment specimens 9, which are evenly distributed circumferentially; and 4 high-speed segment specimens 14, which are evenly distributed circumferentially.

[0034] The graphite throat liner 16 is placed inside the nozzle housing, and the angles of the convergence section and the expansion section and the throat diameter are machined as needed.

[0035] The asphyxiation device and pressure sensor interface are connected to the combustion chamber by welding. The asphyxiation device is connected to a nitrogen cylinder, and the nitrogen supply is controlled by a solenoid valve.

[0036] The low-speed section specimen clamp 5, the convergence section specimen clamp 8, the high-speed section specimen clamp 13 and the low-speed section specimen 6, the convergence section specimen 9, the high-speed section specimen 14 are fastened together by a T-slot structure.

[0037] The solid propellant erosion and combustion measuring device is fixed to the solid propellant erosion and combustion measuring device frame by a front clamp 26, a front support 27, a rear clamp 28, a rear support 29, a fixing bolt 17, a flat washer 18, a spring washer 19, and a fixing nut 20.

[0038] During implementation, the same propellant is used for charge 22, low-speed section test specimen 6, convergence section test specimen 9, and high-speed section test specimen 14. The burning time of the charge should be less than that of the test specimen.

[0039] A method for measuring the erosion and burning rate of solid propellants includes the following steps:

[0040] (1) Ignite the main charge 22 with the ignition charge and record the combustion chamber pressure at the same time.

[0041] (2) When the main charge 22 is burned out, open the solenoid valve of the asphyxiation device and use high-pressure nitrogen to flush out and discharge the gas in the experimental device.

[0042] (3) Take out and measure the remaining thickness of the low-speed section specimen 6, the convergence section specimen 9, and the high-speed section specimen 14, and subtract the initial thickness to obtain the combustion thickness.

[0043] (4) The gas flow velocities in the low-speed section, convergence section, and high-speed section are calculated based on the measured pressure, combustion rate formula, throat diameter, and gas passage diameter.

[0044] (5) Based on the combustion thickness of the specimen under different gas flow rates, the erosion combustion rate of the propellant is obtained and the formula is organized.

[0045] The above description is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

[0046] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A device for measuring the erosion and burning rate of solid propellants, characterized in that: The system includes a front end cap (1), a combustion chamber shell (2), a low-speed section specimen holder (5), a low-speed section specimen (6), a convergent section shell (7), a convergent section specimen holder (8), a convergent section specimen (9), a convergent section bushing (10), a high-speed section shell (11), a high-speed section bushing (12), a high-speed section specimen holder (13), a high-speed section specimen (14), a nozzle shell (15), a throat liner (16), and a propellant charge (22). The front end cap (1), combustion chamber shell (2), convergent section shell (7), high-speed section shell (11), and nozzle shell (15) are sequentially connected to form the cylinder. The low-speed section specimen holder (5) is fixed to the inner surface of the combustion chamber shell (2). The low-speed section specimen (6) is passed through the low-speed section specimen holder (5). The convergent section specimen clamp (8) is fixed inside the convergent section shell (7), the convergent section specimen (9) is fixed by the convergent section specimen clamp (8), the convergent section bushing (10) is set on the inner surface of the convergent section shell (7), one end is in contact with the convergent section specimen clamp (8) and the convergent section specimen (9), and the other end is in contact with the high-speed section bushing (12). The high-speed section specimen clamp (13) is connected to the high-speed section shell (11), the high-speed section specimen (14) is fixed by the high-speed section specimen clamp (13), the throat liner (16) is set on the inner surface of the nozzle shell (15), and the charge (22) is set at the bottom of the combustion chamber shell (2). The low-speed section specimen (6), the convergent section specimen (9) and the high-speed section specimen (14) are propellant specimens.

2. The solid propellant erosion and combustion rate measuring device according to claim 1, characterized in that: It also includes a sealing plug (3) and a pressure cap (4). The combustion chamber housing (2) is provided with a pressure measuring hole and a suffocation device interface. A pressure sensor is connected through the pressure measuring hole, and a suffocation device is connected through the suffocation device interface. The pressure measuring hole and the suffocation device interface are sealed by the sealing plug (3) and the pressure cap (4).

3. The solid propellant erosion and combustion rate measuring device according to claim 1, characterized in that: It also includes fixing bolts (17), flat washers (18), spring washers (19), fixing nuts (20) and sealing rings (21). The front end cap (1), combustion chamber housing (2), convergent section housing (7), high-speed section housing (11) and nozzle housing (15) are all connected by fixing bolts (17), flat washers (18), spring washers (19) and fixing nuts (20), and the connection is sealed by sealing rings (21).

4. The solid propellant erosion and combustion rate measuring device according to claim 1, characterized in that: The low-speed section specimen clamp (5), the convergence section specimen clamp (8) and the high-speed section specimen clamp (13) are respectively provided with multiple T-slots, and multiple low-speed section specimens (6), multiple convergence section specimens (9) and multiple high-speed section specimens (14) are fixed through the T-slots.

5. The solid propellant erosion and combustion rate measuring device according to claim 4, characterized in that: It includes 8 low-speed segment specimens (6), which are evenly distributed in the circumference; 8 convergence segment specimens (9), which are evenly distributed in the circumference; and 4 high-speed segment specimens (14), which are evenly distributed in the circumference.

6. The solid propellant erosion and combustion rate measuring device according to claim 1, characterized in that: The front end cap (1), combustion chamber shell (2), low-speed section specimen clamp (5), convergence section shell (7), convergence section specimen clamp (8), convergence section bushing (10), high-speed section shell (11), high-speed section bushing (12), high-speed section specimen clamp (13), and nozzle shell (15) are made of 30CrMnSi, with a pressure range of 2 to 20 MPa and a maximum working time of 10 s.

7. The solid propellant erosion and combustion rate measuring device according to claim 1, characterized in that: The low-speed section specimen clamp (5) is set at one end of the combustion chamber shell (2) connected to the convergence section shell (7), and the convergence section specimen clamp (8) is set in the middle of the convergence section shell (7). The inner surface is smoothly transitioned through the convergence section bushing (10). The high-speed section specimen clamp (13) is set in the middle of the high-speed section shell (11). The inner surface is smoothly transitioned through the high-speed section bushing (12).

8. The solid propellant erosion and combustion rate measuring device according to claim 1, characterized in that: The same propellant was used for the charge (22), the low-speed section test specimen (6), the convergence section test specimen (9), and the high-speed section test specimen (14).

9. The solid propellant erosion and combustion rate measuring device according to claim 1, characterized in that: The combustion time of the charge (22) is less than that of the low-speed section specimen (6), the convergence section specimen (9), or the high-speed section specimen (14).

10. A method for measuring the erosion and burning rate of solid propellants, characterized in that: The measuring device according to any one of claims 1 to 9 specifically includes the following steps: (1) Ignite the charge (22) and record the combustion chamber pressure; (2) After the charge (22) is burned out, flush and discharge the gas in the experimental device; (3) Take out and measure the remaining thickness of the low-speed section specimen (6), the convergence section specimen (9) and the high-speed section specimen (14), and subtract the initial thickness to obtain the combustion thickness; (4) Calculate the gas flow velocities in the low-speed section, convergence section, and high-speed section; (5) Based on the combustion thickness of the specimen under different gas flow rates, the formula for the propellant erosion combustion rate is obtained.

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