An apparatus for collecting all components of the high-temperature and high-pressure condensed-phase combustion products of a propellant

Abstract

The present invention discloses a device for collecting all components of the high-temperature and high-pressure condensed-phase combustion products of a propellant, comprising: a combustion chamber housing, a piston located at the top of the inner cavity of the combustion chamber housing, with a propellant charge adhered to its lower end, a connecting rod passing through the top of the combustion chamber housing and connected to the top of the piston, an electric pull rod fixed at the top of the inner cavity of the combustion chamber housing, with a pull rope connected to its lower end, a collection bucket located at the bottom of the inner cavity of the combustion chamber housing, containing cooling water therein for collecting the combustion products of the propellant charge, a sleeve, the lower end of which is closed and fixed at the central position of the collection bucket, and a pipe plug is provided at its upper end, the pipe plug is connected to the pull rope, and under the action of the pull rope, the pipe plug is pulled out, so that the sleeve only collects the combustion products of the propellant charge under the high-temperature core area when the influence of the low-temperature shear layer is excluded; the present invention only collects the combustion products of the propellant charge under the high-temperature core area through the sleeve, making the state of the propellant during combustion closer to that of a real engine.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid motors, and particularly relates to a device for collecting all components of high-temperature and high-pressure condensed-phase combustion products of a propellant. Background Art

[0002] The combustion of solid propellants has a decisive influence on the thrust and specific impulse of solid rocket motors. To improve the specific impulse of solid propellants, increase the energy density of propellants, and suppress combustion instability phenomena, generally, about 18% of aluminum powder is contained in the propellant components. The condensed-phase combustion products of solid propellants are mainly Al and its oxidation product Al2O3 particles. The condensed-phase combustion products reduce the specific impulse of the motor, exacerbate the ablation of the insulation layer, exacerbate slag deposition, and affect the combustion stability of the motor. By collecting the condensed-phase combustion products through experiments and conducting particle size, morphology, and physical and chemical analyses on them, the agglomeration characteristics of aluminum particles at the burning surface of the propellant, the evolution process of aluminum particles after leaving the burning surface, and the particle size distribution of the particle phase in the combustion chamber after combustion are obtained.

[0003] At present, the main methods for collecting condensed-phase products are the sampler method and the closed container method. In the sampler method, a specially designed sampler is placed at a certain position in the engine gas plume, and the particles in the gas flow pass through the sampler and are quickly cooled and frozen, thereby collecting the condensed-phase products. This method can collect local condensed-phase products at different combustion times and combustion distances. The disadvantage is that the collection device has a disturbing effect on the plume and cannot collect all particle sizes simultaneously. The closed container method is to burn the propellant in a closed container and freeze the condensed-phase particles through a cooling medium such as nitrogen, water, alcohol, etc. This method is simple, has a high collection efficiency, and can collect a large range of particle sizes. A large number of condensed-phase product collection experiments have been carried out using this method at home and abroad.

[0004] By using the method of optical photography to study the aluminum agglomeration process at the burning surface of the propellant, the formation mechanism of aluminum agglomerates can be clearly revealed. For the particle size distribution of agglomerated particles concerned in engineering practice, it is obtained by statistically analyzing the aluminum particles at the burning surface in the taken photos. However, due to the limitation of the optical field of view and the difference in the selection of statistical samples, the obtained particle size distribution is different from the actual situation. At the same time, due to the interference of smoke and the harsh environment of high temperature and high pressure, the current method of taking photos cannot study the agglomeration phenomenon under high-pressure (>5 MPa) environments.

[0005] The condensed-phase products generated by the combustion of the propellant are collected by the closed container method. This method can collect particles with a wide range of particle sizes and has a high collection rate. Analyzing the collected products can obtain the particle size distribution, appearance morphology, and elemental content of the condensed-phase products during the combustion process. When the propellant burns, the freezing distance of the condensed-phase products, that is, the distance between the burning surface and the collection liquid surface, if it can always be maintained at a very small value (≤5 mm), at this time the freezing distance is much smaller than the distance required for the agglomerated aluminum particles to complete combustion (usually about 50 mm). Therefore, the changes in the agglomerated particles caused by combustion can be ignored. At this time, the large condensed-phase particles collected can be considered as the agglomerates of aluminum at the propellant burning surface.

[0006] At present, the experimental research on aluminum combustion mainly focuses on individual aluminum particles as the research object, studying the effects of oxidation atmosphere (air, O2, H2O, CO2, CO, and propellant combustion product environment, etc.), environmental pressure and temperature, ignition method, etc. on the combustion mode, temperature and product distribution, flame radius, ignition delay, and combustion time of aluminum particles. Tracking the evolution process of individual aluminum particles during combustion excludes the influence of complex interactions between particles on combustion, and thus can reveal the combustion mechanism of aluminum particles. It provides a theoretical basis for the establishment of a comprehensive and detailed aluminum particle combustion model. At the same time, through the analysis of experimental data, an empirical relationship between the combustion time of aluminum particles and the initial particle size, oxidant concentration, environmental pressure, and temperature can be established. In the real high-temperature and high-pressure working environment of the engine, a large number of aluminum particles burn within a very small distance range from the propellant burning surface. The particle size of aluminum particles ranges from a few micrometers to several hundred micrometers, and it involves complex processes such as interactions between particles and between fluid and particles. It is very difficult to directly apply the experimental results of single particles to actual engineering. Therefore, it is necessary to conduct combustion experiments on aluminum particles in the real environment of the engine. Due to the interference of smoke and the harsh environment of high temperature and high pressure, so far, it is impossible to use optical diagnostic methods for relevant research. Using the condensed-phase product collection method to freeze the aluminum particles burning in the real engine and analyzing the obtained condensed-phase products for particle size, morphology, crystal phase, and composition content, etc., can obtain the combustion evolution process of aluminum particles in the air flow. Summary of the Invention

[0007] The purpose of the present invention is to provide a device for collecting all components of the high-temperature and high-pressure condensed-phase combustion products of the propellant, so as to solve the problems of the existing collection device being separated from the real high-temperature environment, low collection efficiency, incomplete collection components, and inability to only collect the combustion products of the propellant grain under the high-temperature core area.

[0008] The present invention adopts the following technical solutions: A device for collecting all components of the high-temperature and high-pressure condensed-phase combustion products of the propellant, including:

[0009] The combustion chamber housing, which is a closed housing,

[0010] The piston is located at the top of the inner cavity of the combustion chamber housing, and a propellant grain is adhered to its lower end.

[0011] The connecting rod passes through the top of the combustion chamber housing and is connected to the top of the piston, and is used to drive the piston to move downward. The moving speed of the piston is equal to the burning speed of the propellant grain.

[0012] The electric pull rod is fixed at the top of the inner cavity of the combustion chamber housing, and a pull rope is connected to its lower end, and is used to pull the pull rope to move upward.

[0013] The collection bucket is located at the bottom of the inner cavity of the combustion chamber housing, and cooling water is contained therein, and is used to collect the combustion products of the grain.

[0014] The casing has its lower end closed and is fixed at the central position of the collection bucket. Its fixed axis coincides with the axis of the grain. A pipe plug is provided at its upper end. The pipe plug is connected to the pull rope, and under the action of the pull rope, the pipe plug is pulled out, so that the casing only collects the combustion products of the propellant grain in the high-temperature core area while discharging and eliminating the influence of the low-temperature shear layer.

[0015] Furthermore, air inlet holes and exhaust holes are provided on the combustion chamber housing, and the air inlet holes and exhaust holes are used to cooperate with each other to generate high pressure in the combustion chamber housing.

[0016] Furthermore, an observation window is provided on the upper half of the combustion chamber housing, and the observation window is used to observe the combustion state of the grain.

[0017] Furthermore, two igniters are installed at the top of the inner cavity of the combustion chamber housing. The lower end of one igniter is connected with an ignition wire. The middle section of the ignition wire bypasses the lower end of the grain and is connected to the lower end of the other igniter. The ignition wire is used to ignite the grain.

[0018] Furthermore, the electric pull rod is electrically connected to an external processing module. The processing module is used to start operating after a predetermined time interval after receiving an ignition signal, and pull out the pipe plug of the casing through the pull rope, so that the casing only collects the combustion products of the propellant grain in the high-temperature core area while discharging and eliminating the influence of the low-temperature shear layer.

[0019] Furthermore, a bracket is further provided at the lower end of the collection bucket, and the bracket is used to adjust the distance between the water level of the collection bucket and the lower burning surface of the grain.

[0020] Furthermore, a filter screen is provided at the exhaust hole.

[0021] Furthermore, a heat-insulating casing is sleeved outside the propellant grain.

[0022] The beneficial effects of the present invention are as follows: By using the casing to collect only the combustion products of the propellant grain under the high-temperature core area, the present invention makes the combustion state of the propellant closer to that of a real engine. The present invention can visually observe the agglomeration process of aluminum on the propellant burning surface, and at the same time measure the spatial distribution of the evolution process of aluminum particles after leaving the burning surface, providing data support for the research on multiphase combustion flow in the engine. The present invention can observe the agglomeration process of aluminum on the propellant burning surface and the evolution process of the agglomerated aluminum particles after leaving the burning surface. The present invention uses distilled water as the cooling medium, and the burning surface is always maintained at a constant position, and at the same time, the distance between the burning surface and the collecting liquid surface can be adjusted; in addition, a filter screen is provided at the exhaust hole to collect all components of the combustion products of the grain, avoiding the problem of the escape of combustion product microparticles during exhaust after the experiment and collecting all components of the condensed-phase combustion products. Brief Description of the Drawings

[0023] Figure 1 is a cross-sectional view of the present invention;

[0024] Figure 2 is a schematic structural diagram of the present invention.

[0025] Wherein: 1, combustion chamber housing; 2, piston; 3, connecting rod; 4, electric pull rod; 5, collection bucket; 6, casing; 7, igniter; 8, pull rope; 9, air inlet hole; 10, exhaust hole; 11, observation window. Detailed Description of the Invention

[0026] The present invention will be described in detail below in conjunction with the drawings and specific embodiments.

[0027] The present invention discloses a device for collecting all components of high-temperature and high-pressure condensed-phase combustion products of a propellant, as shown in Figure 1 and Figure 2 shown, including a combustion chamber housing 1, a piston 2, a connecting rod 3, an electric pull rod 4, a collection bucket 5, and a casing 6.

[0028] The combustion chamber housing 1 is a closed housing. The piston 2 is located at the top of the inner cavity of the combustion chamber housing 1. A propellant grain is adhered to the lower end of the piston 2. The connecting rod 3 passes through the top of the combustion chamber housing 1 and is connected to the top of the piston 2. The connecting rod 3 is used to drive the piston 2 to move downward, and the moving speed of the piston 2 is equal to the burning speed of the propellant grain.

[0029] The electric pull rod 4 is fixed at the top of the inner cavity of the combustion chamber housing 1. A pull rope 8 is connected to the lower end of the electric pull rod 4. The electric pull rod 4 is used to pull the pull rope 8 to move upward. The collection bucket 5 is located at the bottom of the inner cavity of the combustion chamber housing 1. Cooling water is contained in the collection bucket 5. The collection bucket 5 is used to collect the combustion products of the grain.

[0030] The lower end of the sleeve 6 is closed and fixed at the central position of the collection bucket 5. The axis of the fixed sleeve 6 coincides with the axis of the propellant grain. A pipe plug is provided at the upper end of the sleeve 6. The pipe plug is connected to the pull rope 8 and is pulled open under the action of the pull rope 8, so that the sleeve 6 only collects the combustion products of the propellant grain in the high-temperature core area when the influence of the low-temperature shear layer is excluded.

[0031] Temperature is the key factor determining the combustion of aluminum in the propellant. A low ambient temperature will cause incomplete combustion of aluminum particles. During the combustion of the propellant in the experiment, the periphery of the propellant grain is in contact with the cold environment, so there is a high-low temperature shear layer around the propellant grain, resulting in a low and uneven temperature on the periphery, which in turn causes incomplete combustion of aluminum particles. If such particles are collected, it will affect the analysis accuracy of the combustion efficiency because the particles in the actual engine all burn in a high-temperature hot environment. Therefore, the sleeve 6 is provided to exclude the influence of the low-temperature shear layer and ensure that only the combustion products burning in the high-temperature flame core area are collected.

[0032] An air inlet hole 9 and an exhaust hole 10 are provided on the combustion chamber housing 1. The air inlet hole 9 and the exhaust hole 10 are used to cooperate with each other to generate high pressure inside the combustion chamber housing 1. An observation window 11 is provided in the upper half of the combustion chamber housing 1. The observation window 11 is used to observe the combustion state of the propellant grain.

[0033] Two igniters 7 are installed on the combustion chamber housing 1. The lower end of one igniter 7 is connected with an ignition wire. The middle section of the ignition wire bypasses the lower end of the propellant grain and is then connected to the lower end of the other igniter 7. The ignition wire is used to ignite the propellant grain.

[0034] The electric pull rod 4 is electrically connected to an external processing module. The processing module is used to start operating after a predetermined time interval after receiving the ignition signal and pull open the pipe plug of the sleeve 6, so that the sleeve 6 collects the condensed-phase combustion products in the high-temperature core area. Among them, the predetermined time is 1 s because the propellant grain is in a cold environment at the beginning of combustion, resulting in incomplete combustion of the condensed-phase particles and affecting the particle size of the collected products. Therefore, the sleeve 6 needs to be added to achieve the time and space selective collection of the condensed-phase combustion products.

[0035] A bracket is further provided at the lower end of the collection bucket 5. The bracket is used to adjust the distance between the water level of the collection bucket 5 and the lower combustion surface of the propellant grain. The distance between the water level of the collection bucket 5 and the lower combustion surface of the propellant grain can be adjusted through the bracket, so as to collect the condensed-phase products of different combustion processes to simulate the different positions of aluminum particles in the actual engine.

[0036] During the operation of the present invention, as the propellant grain burns, the connecting rod 3 pushes the piston 2 downward. The movement speed of the piston 2 is equal to the burning speed of the propellant grain, and the working time is equal to the burning time of the grain. At this time, the downward movement of the piston 2 exactly compensates for the increase in the frozen distance caused by the burning of the burning surface. Therefore, the position of the burning surface remains unchanged and is always flush with the upper end surface inside the combustion chamber. The burning distance of the aluminum particles in the gas is controlled by adjusting the height of the distilled water level in the collection bucket 5. After the agglomerated aluminum particles leave the burning surface, they are quickly cooled and frozen by the distilled water. During the working process, the gas is discharged through the solenoid valve and the safety valve to keep the pressure in the combustion chamber constant.

[0037] The present invention adjusts the pressure inside the combustion chamber housing 1 through the intake hole 9, the exhaust hole 10, and the external high-pressure transportation system; measures the pressure change inside the combustion chamber housing 1 through the pressure transmitter in the data acquisition system; observes the generation change and combustion state of the condensed-phase products on the surface of the propellant grain through the high-speed camera through the observation window 11; measures the temperature and conducts the burning rate test through the thermocouple.

[0038] The working process of the present invention is as follows:

[0039] Close the exhaust valve of the exhaust hole 10, open the intake valve of the intake hole 9. After pre-inflating the combustion chamber housing 1 and discharging the air inside the combustion chamber, close the exhaust valve, and then continue to inflate the combustion chamber housing 1 to the predetermined experimental pressure. Set the working parameters of the external driving device connected to the connecting rod 3 to make the output linear movement speed equal to the burning rate of the propellant grain and the working time equal to the burning time of the propellant grain. When the internal pressure value of the combustion chamber housing collected by the pressure transmitter reaches the required value through observation, close the intake valve, ignite with the heating wire, save the experimental data after the combustion ends, relieve the pressure, collect the products, and conduct the next experiment.

[0040] The propellant grain is an aluminum-containing composite propellant, and the adopted grain is a columnar structure with a diameter h = 30 mm. The larger burning surface of the propellant grain makes the test conditions closer to the real engine environment. During assembly, the grain is bonded to the lower end surface of the piston 2 through an adhesive. In order to ensure constant-surface combustion, the side and one end surface of the propellant grain are coated. The maximum allowable burning rate of the propellant grain is limited by the maximum rated speed of the driving device. In the test, it is required that the burning rate of the propellant grain does not exceed 50 mm / s. In order to reduce the ignition delay time of the propellant grain, the method of using a thermosensitive drug plus a resistance wire is adopted for ignition.

[0041] The present invention can observe the agglomeration process of aluminum on the burning surface of the propellant grain and the evolution process after the agglomerated aluminum particles leave the burning surface, accumulate relevant experimental data for the aluminum agglomeration model and the combustion model, make the state of the propellant grain during combustion closer to that of a real engine by setting the sleeve 6; avoid the problem of the escape of combustion product microparticles during exhaust after the experiment by setting a filter screen at the exhaust hole 10, and collect all components of the condensed-phase combustion products; and observe the aluminum agglomeration process at the burning surface of the propellant grain by setting an observation window 11 for optical photography.

[0042] An adiabatic sleeve is sleeved outside the propellant grain, and the grain is burned inside the adiabatic sleeve. The size of the adiabatic sleeve corresponds to different residence times of aluminum particles. Once the particles escape from the adiabatic sleeve, they enter the cold environment and freeze. Therefore, by changing the length of the adiabatic sleeve, the residence time of aluminum particles can be adjusted. For aluminum particles at different positions in the engine, the design of the adiabatic sleeve can achieve the collection of condensed-phase products with different combustion histories to simulate the different positions of aluminum particles in the actual engine.

[0043] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A device for collecting all components of the high-temperature and high-pressure condensed-phase combustion products of a propellant, characterized in that, Comprising: A combustion chamber housing (1), which is a closed housing, A piston (2), located at the top of the inner cavity of the combustion chamber housing (1), and a propellant grain is adhered to the lower end thereof, A connecting rod (3), passing through the top of the combustion chamber housing (1) and connected to the top of the piston (2), for driving the piston (2) to move downward, and the moving speed of the piston (2) is equal to the burning speed of the propellant grain, An electric pull rod (4), fixed at the top of the inner cavity of the combustion chamber housing (1), and a pull rope (8) is connected to the lower end thereof, for pulling the pull rope (8) to move upward, A collection bucket (5), located at the bottom of the inner cavity of the combustion chamber housing (1), and filled with cooling water therein, for collecting the combustion products of the grain, A sleeve (6), the lower end of which is closed and fixed at the central position of the collection bucket (5), the fixed axis thereof coincides with the axis of the grain, a pipe plug is provided at the upper end thereof, the pipe plug is connected to the pull rope (8), and under the action of the pull rope (8), the pipe plug is pulled out, so that the sleeve (6) only collects the combustion products of the propellant grain in the high-temperature core area under the condition of discharging and eliminating the influence of the low-temperature shear layer.

2. The all-component collection device for high-temperature and high-pressure condensed-phase combustion products of a propellant according to claim 1, wherein An air inlet hole (9) and an exhaust hole (10) are provided on the combustion chamber housing (1), and the air inlet hole (9) and the exhaust hole (10) are used to cooperate with each other to generate high pressure in the combustion chamber housing (1).

3. The all-component collection device for the high-temperature and high-pressure condensed-phase combustion products of a propellant according to claim 2, characterized in that, An observation window (11) is provided on the upper half of the combustion chamber housing (1), and the observation window (11) is used to observe the combustion state of the grain.

4. The all-component collection device for the high-temperature and high-pressure condensed-phase combustion products of a propellant according to claim 3, wherein, Two igniters (7) are installed at the top of the inner cavity of the combustion chamber housing (1), a lower end of one igniter (7) is connected with an ignition wire, the middle section of the ignition wire bypasses the lower end of the grain and then is connected with the lower end of the other igniter (7), and the ignition wire is used to ignite the grain.

5. A device for collecting all components of the high-temperature and high-pressure condensed-phase combustion products of a propellant according to any one of claims 1-4, characterized in that, The electric pull rod (4) is electrically connected to an external processing module, and the processing module is used to start operating after a predetermined time interval after receiving an ignition signal, and pull out the pipe plug of the sleeve (6) through the pull rope (8), so that the sleeve (6) only collects the combustion products of the propellant grain in the high-temperature core area under the condition of discharging and eliminating the influence of the low-temperature shear layer.

6. The all-component collection device for high-temperature and high-pressure condensed-phase combustion products of a propellant according to claim 5, characterized in that, A bracket is further provided at the lower end of the collection bucket (5), and the bracket is used to adjust the distance between the water level of the collection bucket (5) and the lower burning surface of the grain.

7. The all-component collection device for high-temperature and high-pressure condensed-phase combustion products of a propellant according to claim 6, characterized in that, A filter screen is provided at the exhaust hole (10).

8. The all-component collection device for the high-temperature and high-pressure condensed-phase combustion products of a propellant according to claim 7, characterized in that, An adiabatic sleeve is sleeved outside the propellant grain.

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