A method for predicting the energy conversion and external work of a projectile in a launch path

Abstract

The present invention relates to a method for predicting the energy conversion and external work of a projectile in a launch channel, and belongs to the field of insensitive charge design and prediction. The method comprises: establishing a model of energy conversion and work in the launch channel; obtaining the real-time pressure inside the launch channel after charge ignition through a pressure sensor of a launch device, and obtaining the prediction results of the energy conversion of the projectile in the launch channel and the initial velocity of the projectile according to the real-time pressure and the model of energy conversion and work in the launch channel. The method constructs a model of energy conversion and work in the launch channel based on the function of the internal energy of the charge gas product, the function of constraining the external work of the charge system, and the function of the mass increase rate of the gas product, and realizes the prediction of the energy conversion result of the projectile in the launch channel and the initial velocity of the projectile on the basis of the modeling, which solves the current problems of lack of a method for modeling energy conversion and external work in the launch channel and lack of a method for predicting energy conversion in the launch channel and the initial velocity of the projectile.

Description

Technical Field

[0001] The invention relates to the field of insensitive constrained charge design and prediction, and in particular to a method for predicting energy conversion and external work of a projectile in a launch channel. Background Art

[0002] The initial velocity of a projectile is one of the important parameters for measuring the performance of a launch system, and it directly affects the range, accuracy, and penetration of the projectile. At present, the initial velocity of a projectile is mainly changed by manually adjusting the amount of charge. In order to maintain high pressure after launch, the initial velocity of the projectile is usually increased by increasing the amount of charge, but this will produce high chamber pressure, which will cause damage to the structure of the charge device and may even cause accidents that threaten the safety of the operator. With the rapid development of constrained charge launch technology in recent years, it is particularly important to optimize the initial velocity of the projectile by studying the charge combustion process.

[0003] During the launch of constrained charges, the launch path effect has an important influence on improving the initial velocity, range, power and accuracy of the projectile. However, the current understanding of the motion behavior and characteristics of the projectile in the launch path is still insufficient, especially the formation mechanism and influence of energy conversion and external work in the launch path are not clear.

[0004] Therefore, how to realize the modeling of the energy conversion and work done by the projectile in the launch path, and based on the modeling, realize the prediction of the energy conversion of the projectile in the launch path and the initial velocity of the projectile, so as to provide a reference basis for the optimal control of the initial velocity of the projectile, is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a method for predicting the energy conversion and external work done by a missile in a launch path, so as to solve the current problems of lack of a modeling method for the energy conversion and external work done in a launch path and lack of a method for predicting the energy conversion in the launch path and the initial velocity of the missile.

[0006] The present invention provides a method for predicting energy conversion and external work of a projectile in a launch path, the method comprising the following steps:

[0007] A model of energy conversion and work done in the launch path is established based on the law of conservation of energy, the laws of thermodynamics, fluid mechanics and interior ballistics;

[0008] The real-time pressure inside the launch channel after the charge is ignited is obtained by a pressure sensor of the launch device, and the energy conversion of the projectile in the launch channel and the prediction result of the initial velocity of the projectile are obtained according to the real-time pressure and the model of energy conversion and work in the launch channel; wherein the prediction result of the energy conversion of the projectile in the launch channel includes the internal energy of the charge gas product, the kinetic energy of the projectile, and the kinetic energy of the charge gas product; the initial velocity of the projectile is the velocity of the projectile when it leaves the exit of the launch channel.

[0009] Furthermore, the launch device includes: a restraining body, a laser ignition device, a pressure testing device, a charge, and a projectile;

[0010] The constraint body comprises an inner constraint body and an outer constraint body; a cylindrical first cavity is arranged at the center of the inner constraint body, a plug is arranged at the bottom of the first cavity, and a diaphragm covers the top of the first cavity, so that the first cavity forms a closed chamber, and the charge is located in the closed chamber; a groove is arranged at the upper part of the outer constraint body, and a cylindrical second cavity is arranged at the lower part; the lower part of the inner constraint body is embedded in the groove of the outer constraint body, and the first cavity is aligned with the second cavity along the center line;

[0011] The missile is located at the bottom of the second cavity, the tail of the missile is flush with the bottom of the second cavity and fits tightly with the second cavity, and the second cavity serves as a launch path; the inner and outer restraint bodies are fixed by flange structures;

[0012] The laser ignition device is located above the inner constraint body and is used to emit laser to the charge to ignite the charge by the laser;

[0013] The pressure testing device is located on the side wall of the inner constraint body and is used to measure the pressure in the closed chamber inside the inner constraint body.

[0014] Furthermore, the real-time pressure inside the launch channel is brought into the model of energy conversion and work done in the launch channel to obtain the prediction result of the projectile movement speed; when When , the predicted result of the initial velocity of the projectile is obtained.

[0015] Furthermore, based on the laws of thermodynamics and the ideal gas state equation, a function of the internal energy of the charge gas products in the constrained charge system is established; based on fluid mechanics and the Lagrangian method, a function of the kinetic energy of the charge gas products is established, and based on the function of the kinetic energy of the projectile and the kinetic energy of the gas products, a function of the external work done by the constrained charge system is established; based on Vielle's law, a function of the rate of increase of the mass of the gas products is obtained; based on the law of conservation of energy and interior ballistics, a function of energy and work in the launch channel is established, and the function of the internal energy of the charge gas products, the function of the external work done by the constrained charge system and the function of the rate of increase of the mass of the gas products are substituted into the energy and work function in the launch channel to obtain a model of energy conversion and work done in the launch channel.

[0016] Furthermore, the process of energy conversion and work-doing of the projectile in the launch channel is divided into a first process and a second process. The starting time of the first process is the ignition time of the ignition device, and the ending time is the time when the charge reaction is completed; the starting time of the second process is the time when the charge reaction is completed, and the ending time is the time when the projectile reaches the exit of the launch channel;

[0017] The models of energy conversion and work done in the emission channel corresponding to the first process and the second process are:

[0018] ,

[0019] in, is the energy released per unit mass of charge, is the burning rate coefficient, is the density of the solid charge, is the cross-sectional area of ​​the solid charge column, is the ignition timing of the ignition device, is the burning rate pressure index, is the internal pressure of the launch channel, To absorb the energy input from the outside for the charge, is the mass of the gas product, is the initial volume of space between the charge and the projectile, is the mass of the projectile, is the projectile speed, is the cross-sectional area of ​​the launch channel, is the adiabatic index, In order to limit the heat exchanged between the charge system and the outside world, The moment when the charge reaction is completed. It is the moment when the missile reaches the exit of the launch track.

[0020] Furthermore, based on the model of energy conversion and work in the launch channel, expressions for the internal energy of the charge gas product, the kinetic energy of the projectile, and the kinetic energy of the charge gas product are obtained, namely, formulas (1)-(3). The real-time pressure inside the launch channel after the charge is ignited and the predicted results of the projectile movement speed are substituted into formulas (1)-(3) to obtain the internal energy of the charge gas product, the kinetic energy of the projectile, and the kinetic energy of the charge gas product, respectively.

[0021] The internal energy of the charge gas product is expressed as:

[0022] , (1)

[0023] in, is the internal energy of the charge gas product, is the internal pressure of the launch channel, is the initial volume of space between the charge and the projectile, is the cross-sectional area of ​​the launch channel, is the ignition timing of the ignition device, is the projectile speed, is the adiabatic index;

[0024] The kinetic energy of a missile is expressed as:

[0025] , (2)

[0026] in, is the kinetic energy of the missile, is the mass of the missile;

[0027] The kinetic energy of the charge gas product is expressed as:

[0028] , (3)

[0029] in, is the kinetic energy of the charge gas product, is the mass of the gas product.

[0030] Furthermore, the laser ignition device includes a control console, a laser probe, a reflector and a sapphire window; the control console is connected to the laser probe and is used to set the power of the emitted laser; the laser probe is used to emit laser to the reflector; the reflector is located above the sapphire window and is used to reflect the incident laser to the sapphire window; the sapphire window is located at the upper end of the plug in the inner constraint body, and a through hole is provided at the center of the plug, and the laser reflected by the reflector passes through the through hole and the sapphire window in sequence and then enters the charge, and the charge is ignited by the laser.

[0031] Furthermore, the pressure testing device includes a pressure sensor, a charge amplifier, an oscilloscope, and a pressure sensor mounting piece; the pressure sensor is mounted on the pressure sensor mounting piece and is connected in series with one end of the charge amplifier to measure the pressure in the closed chamber inside the constraint body; the other end of the charge amplifier is connected in series with the oscilloscope to set the amplification factor to amplify the pressure signal obtained by the pressure sensor; the oscilloscope is used to sample and record the pressure signal amplified by the charge amplifier; the pressure sensor mounting piece is installed with an opening on the side wall of the inner constraint body so that the gas in the closed chamber inside the inner constraint body contacts the pressure sensor.

[0032] Further, the function of the gas product mass increase rate is:

[0033] ,

[0034] in, is the rate of increase of gas product mass, is the density of the solid charge, is the cross-sectional area of ​​the solid charge column, is the burning rate of the charge, i.e., the rate of combustion;

[0035] It is expressed as:

[0036] ,

[0037] in, is the burning rate coefficient, is the burning rate pressure index, is the internal pressure of the launch channel.

[0038] Furthermore, the energy and work function in the emission channel is:

[0039] ,

[0040] in, It is the sum of the chemical energy generated by the combustion of the charge and the energy absorbed by the charge from the outside. is the internal energy of the charge gas product, In order to limit the heat exchanged between the charge system and the outside world, To constrain the charge system to do work externally;

[0041] It is expressed as:

[0042] ,

[0043] in, is the energy released per unit mass of charge, is the ignition timing of the ignition device, is the rate of increase of gas product mass, To absorb the energy input from the outside world for the charge.

[0044] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0045] 1. The present invention brings the function of the internal energy of the charge gas product, the function of the external work done by the constrained charge system and the function of the gas product mass increase rate into the energy and work function in the launch channel to obtain the model of energy conversion and work done in the launch channel, which solves the current problem of unclear formation mechanism and influence of energy conversion and external work done in the launch channel.

[0046] 2. The present invention divides the process of energy conversion and work done by the projectile in the launch channel into a first process and a second process. According to the difference in the mass of the gas products in the two processes, a model of energy conversion and work done in the launch channel corresponding to the first process and the second process is obtained, and the prediction results of the energy conversion of the projectile in the launch channel and the initial velocity of the projectile are obtained according to the real-time pressure and the model, thereby improving the accuracy of the prediction results of the energy conversion in the launch channel and the initial velocity of the projectile.

[0047] 3. The present invention provides a theoretical basis for evaluating the loss of energy conversion of a projectile in a launch channel by establishing a model of energy conversion and work done in a launch channel and a charge reactivity model.

[0048] 4. The present invention not only improves the airtightness of the prediction system by installing a diaphragm between the inner and outer constraints, but also allows the generated gas products to break through the diaphragm and then act on the projectile after stabilization, thereby improving the strength of the force and the stability of the projectile. The present invention not only improves the airtightness of the prediction system by using the truncated cone structure at the tail of the projectile, but also allows the gas products to act more evenly on the tail of the projectile, thereby improving the stability of the projectile. The present invention adapts different pressure sensors through the pressure sensor mounting part, and there is no need to open holes of different sizes on the prediction system according to the size of different pressure sensors, thereby improving versatility; and it solves the problem that the hole required to directly open the pressure sensor on the system needs to be longer, but the actual device cannot meet the hole length requirement.

[0049] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The accompanying drawings are only used for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. In the entire drawings, the same reference symbols represent the same components;

[0051] Figure 1 It is a flow chart of a method for predicting energy conversion and external work of a projectile in a launch channel according to an embodiment of the present invention;

[0052] Figure 2 is a block diagram of a transmitting device according to an embodiment of the present invention;

[0053] Figure 3 This is a schematic diagram of the tail of a projectile according to an embodiment of the present invention;

[0054] Figure 4It is a schematic diagram of the real-time pressure corresponding to the first charge and the second charge according to an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0056] Embodiment 1

[0057] A specific embodiment of the present invention discloses a method for predicting the energy conversion and external work of a projectile in a launch path. Figure 1 As shown, the method comprises the following steps:

[0058] Step S1, establishing a model of energy conversion and work done in the launch path based on the law of conservation of energy, the laws of thermodynamics, fluid mechanics and interior ballistics;

[0059] Step S2, obtaining the real-time pressure inside the launch channel after the charge is ignited through the pressure sensor of the launch device, and obtaining the predicted results of the energy conversion of the projectile in the launch channel and the initial velocity of the projectile based on the real-time pressure and the model of energy conversion and work in the launch channel; wherein the predicted results of the energy conversion of the projectile in the launch channel include the internal energy of the charge gas product, the kinetic energy of the projectile, and the kinetic energy of the charge gas product; the initial velocity of the projectile is the velocity of the projectile when it leaves the exit of the launch channel.

[0060] Specifically, in step S1, a function of the internal energy of charge gas products in a constrained charge system is established based on the laws of thermodynamics and the ideal gas state equation; a function of the kinetic energy of charge gas products is established based on fluid mechanics and the Lagrangian method, and a function of the external work done by the charge system is established based on the kinetic energy of the projectile and the kinetic energy of the gas products; a function of the rate of increase of the mass of the gas products is obtained based on Vielle's law; a function of energy and work done in a launch channel is established based on the law of conservation of energy and interior ballistics, and the function of the internal energy of charge gas products, the function of the external work done by the constrained charge system and the function of the rate of increase of the mass of the gas products are brought into the energy and work function in the launch channel to obtain a model of energy conversion and work done in the launch channel.

[0061] Specifically, the constrained charge system is composed of a projectile, a charge, a launch track and an ignition device. The charge begins to burn after being ignited by the ignition device, and continuously produces gas products in the launch track, thereby converting the chemical energy of the charge into the internal energy of the gas products. As the combustion continues, the gas products continue to increase, thereby causing the pressure in the launch track to continue to increase. Under the action of the continuous increase in the internal pressure of the launch track, the high-temperature and high-pressure gas products expand and do work, converting the internal energy of the gas products into the kinetic energy of the projectile and the gas products. It can be seen that the above process is a process in which the chemical energy of the charge in the launch track is continuously converted into the internal energy of the gas products, and finally converted into the kinetic energy of the projectile and the gas products, and work is done externally.

[0062] It should be noted that this application studies the formation mechanism of energy conversion and work of the projectile in the launch channel. Therefore, the starting time of the study is the ignition time of the ignition device, and the ending time is the time when the projectile reaches the exit of the launch channel. The detonation method of the charge in this application is to ignite it through the ignition device to make it burn, rather than detonate, to avoid the destruction and deformation of the restrained charge system caused by detonation; and, in this application, the charge produces a large amount of gas products relatively slowly during the combustion reaction, rather than exploding instantly, to avoid the destruction and deformation of the restrained charge system caused by explosion.

[0063] Furthermore, assuming that the gas product expands isentropically, the laws of thermodynamics yield:

[0064] , (1)

[0065] in, is the internal energy of the charge gas product, is the molar heat capacity at constant pressure, is the number of moles, is the absolute temperature of the gas product, is the internal pressure of the launch channel, is the volume of space between the charge and the projectile, is the ignition timing of the ignition device, is the time variable.

[0066] Furthermore, based on the ideal gas state equation, we can obtain:

[0067] , (2)

[0068] in, is the ideal gas constant.

[0069] Specifically, from the ideal gas state equation we know:

[0070] , (3)

[0071] therefore, , (4)

[0072] Substituting (4) into (1), we can obtain equation (2).

[0073] Specifically, from the ideal gas state equation we know:

[0074] , (5)

[0075] in, is the molar heat capacity at constant volume;

[0076] , (6)

[0077] in, is the adiabatic index;

[0078] From (5) and (6), we can get formula (7):

[0079] (7)

[0080] Substituting equation (7) into equation (2), we get the function of the internal energy of the charge gas product:

[0081] (8)

[0082] Specifically, It is expressed by the following formula:

[0083] , (9)

[0084] in, is the initial volume of space between the charge and the projectile, is the projectile speed, is the cross-sectional area of ​​the launch channel.

[0085] It should be noted that in the constrained charge system, the launch path is cylindrical, so the charge is also cylindrical before ignition and combustion, and is separated from the projectile by a certain distance, with a certain initial space volume between the two. The gas products generated after the charge ignites and burns will fill the initial space volume, and then begin to expand outward and do work, pushing the projectile to move, causing the space volume between the two to continue to increase.

[0086] Furthermore, the work done by the constrained charge system can be expressed as:

[0087] , (10)

[0088] in, To constrain the charge system to do work externally.

[0089] It should be noted that the negative sign in the above formula represents the work done by the constrained charge system on the environment. After the charge is ignited, gas products are continuously generated, causing the pressure inside the constrained charge system to continue to increase. The high-pressure gas expands in the launch channel while pushing the projectile to accelerate, forming expansion work. In addition, the chemical reaction evolution of the charge is also ongoing. Therefore, the energy release generated by the combustion and the external work generated by the constrained charge system exist simultaneously. The coupling effect of the two forms the energy conversion and work of the projectile in the launch channel.

[0090] Specifically, the work done by the restrained charge system includes: work done on the projectile, work done by the projectile to overcome friction, work done by movement of gas products, work done by the recoil of the restrained charge system, and work done by the projectile to overcome the resistance of the air column.

[0091] Furthermore, the work done on the projectile, i.e., applying pressure to the projectile, gradually converts the internal energy of the charge into the kinetic energy of the projectile. Therefore, the work done on the projectile is expressed by the following formula:

[0092] , (11)

[0093] in, is the kinetic energy of the missile, is the mass of the projectile.

[0094] Furthermore, while the gaseous product propels the projectile, its own expansion also has kinetic energy. Therefore, the work done by the movement of the gaseous product is represented by the kinetic energy of the gaseous product.

[0095] Specifically, based on the assumption that the Lagrangian fluid mass is uniformly distributed, we can obtain:

[0096] , (12)

[0097] in, is the distance between the bottom of the missile and the bottom of the launch track at the current moment, is the mass of gas products at the current moment, is the differential unit layer of gas products at the current moment, It is the mass of the fluid in the differential unit layer of the gas product at the current moment.

[0098] It should be noted that in fluid mechanics, the Lagrangian method uses material derivatives to represent the change of fluid over time. The differential unit layer of the above gas product represents the product gas uniformly distributed in the emission channel being divided vertically into microelements along the emission channel.

[0099] Specifically, assuming that the velocity of the gas product is linearly distributed, we can obtain:

[0100] , (13)

[0101] in, is the flow rate of the gas product at the current moment, that is, the speed of the gas product; is the velocity of the projectile at the current moment; It is the distance between the differential unit layer of the gas product and the bottom of the emission channel at the current moment.

[0102] Further, the kinetic energy of the differential unit layer of the gas product is expressed as:

[0103] , (14)

[0104] in, is the kinetic energy of the current differential unit layer of the gas product.

[0105] Specifically, by substituting equations (12) and (13) into equation (14), we can obtain:

[0106] (15)

[0107] Specifically, by integrating the above formula, we can get the function of the kinetic energy of the charge gas product as:

[0108] , (16)

[0109] in, is the kinetic energy of the charge gas product, is the mass of the gas product.

[0110] Specifically, from the bottom of the launch channel Start integrating until the bottom of the missile, so the lower limit of integration is , the upper limit of the integral is ,at this time, .

[0111] It should be noted that, since it is not desirable to generate work by the projectile to overcome friction in practical applications, the projectile and the inner wall of the launch channel are designed to be very smooth, so that the friction is very small. According to historical experimental data, the work done by the projectile to overcome friction accounts for less than 3% of the external work done by the constrained charge system, so it can be ignored. Since it is also not desirable to generate recoil work by the constrained charge system in practical applications, the constrained charge system is usually heavier, and the combustion is slower than the detonation energy release, so that the recoil of the constrained charge system is very small. According to historical experimental data, the recoil work of the constrained charge system accounts for less than 2% of the external work done by the constrained charge system, so it can be ignored. Since the launch channel is very short in practical applications, the air column formed between the top of the projectile and the launch channel outlet is very short, so that the projectile does very little work to overcome the air column resistance. According to historical experimental data, the work done by the projectile to overcome the air column resistance accounts for less than 1% of the external work done by the constrained charge system, so it can be ignored.

[0112] In summary, the function of constrained charge system doing external work is established as:

[0113] (17)

[0114] Furthermore, because the charge combustion satisfies Vielle's law, the function of the mass increase rate of the gas product per unit time based on Vielle's law is:

[0115] , (18)

[0116] in, is the rate of increase of gas product mass, is the density of the solid charge, is the cross-sectional area of ​​the solid charge column, is the burning rate of the charge, that is, the combustion rate.

[0117] Specifically, It is expressed as:

[0118] , (19)

[0119] in, is the burning rate coefficient, is the burning rate pressure index.

[0120] Furthermore, based on the law of conservation of energy and interior ballistics, the energy and work function in the launch path is established as:

[0121] , (20)

[0122] in, It is the sum of the chemical energy generated by the combustion of the charge and the energy absorbed by the charge from the outside. To limit the heat exchanged between the charging system and the outside world.

[0123] Further, It is expressed as:

[0124] , (twenty one)

[0125] in, is the energy released per unit mass of charge, To absorb the energy input from the outside world for the charge.

[0126] It should be noted that when the ignition device ignites the charge, the charge will absorb external input energy. For example, when a laser is used for ignition, the laser will generate input energy. Smaller.

[0127] Furthermore, by substituting the function of the internal energy of the charge gas product, i.e., equation (8), and the function of the external work performed by the charge system, i.e., equations (17) and (21), into the energy and work function in the launch channel, we can obtain:

[0128] . (twenty two)

[0129] Furthermore, the process of energy conversion and work performance of the projectile in the launch channel is divided into a first process and a second process. The starting time of the first process is the ignition time of the ignition device, and the ending time is the time when the charge reaction is completed; the starting time of the second process is the time when the charge reaction is completed, and the ending time is the time when the projectile reaches the exit of the launch channel.

[0130] It should be noted that the process of energy conversion and work done by the projectile in the launch channel includes chemical reaction and physical work. In the first process, chemical reaction and physical work exist simultaneously, and in the second process, only physical work exists.

[0131] Furthermore, by substituting the functions of the gas product mass increase rate, i.e., equations (18), (9), and (19), into equation (22), the models of energy conversion and work done in the emission channel corresponding to the first process and the second process are obtained as follows:

[0132] ,(twenty three)

[0133] in, The moment when the charge reaction is completed. It is the moment when the missile reaches the exit of the launch track.

[0134] It should be noted that in this application, the heat exchanged between the charge system and the outside world is restricted. It is very small and can be ignored. If necessary, it can be estimated by correction In the first process, since the chemical reaction has not been completed, the gas product is still increasing, so the mass of the gas product is obtained based on Vielle's law. In the second process, since the chemical reaction has been completed, the mass of the gas product is .

[0135] It can be understood that the present invention brings the function of the internal energy of the charge gas product, the function of the external work done by the constrained charge system, and the function of the gas product mass increase rate into the energy and work function in the launch channel to obtain the model of energy conversion and work done in the launch channel, which solves the current problem of unclear formation mechanism and influence of energy conversion and external work done in the launch channel. The present invention divides the process of energy conversion and work done by the projectile in the launch channel into a first process and a second process, and obtains the model of energy conversion and work done in the launch channel corresponding to the first process and the second process according to the difference in the mass of the gas product in the two processes, thereby improving the accuracy of obtaining energy conversion and external work done in the launch channel.

[0136] Preferably, the charge reactivity model is obtained by the following formula:

[0137] , (twenty four)

[0138] in, is the reactivity of the charge.

[0139] It should be noted that the reactivity of the charge represents the degree of chemical reaction and energy release of the charge, which is the mass of the reacted charge divided by the total mass of the charge. In the combustion reaction mode, when the charge reaction is completed, that is, At this moment, the charge's responsiveness is 100%.

[0140] It can be understood that the present invention provides a theoretical basis for evaluating the loss of energy conversion of a projectile in a launch channel by establishing a model of energy conversion and work done in a launch channel and a charge reactivity model.

[0141] Specifically, in step S2, based on the above-mentioned model of energy conversion and work in the launch path, the model can be used as a basis to obtain the prediction results of the energy conversion of the projectile in the launch path and the initial velocity of the projectile.

[0142] Specifically, the real-time pressure inside the launch channel is brought into the model of energy conversion and work done in the launch channel to obtain the prediction result of the projectile movement speed; when When , the predicted result of the initial velocity of the projectile is obtained.

[0143] It should be noted that in the combustion reaction mode, when the charge reaction is completed, that is, At this moment, the reactivity of the charge is 100%, and the solid charge turns into gaseous products, but its mass remains unchanged, that is, The prediction system for energy conversion and external work of projectiles in the launch channel provided by this application adopts laser ignition and uses black powder as ignition powder. Black powder is easy to burn and the ignition time is very short, so the charge absorbs the energy input from the outside. Very small, can be ignored; the launch path of the prediction system is very short, so that the heat exchanged between the above system and the outside world is very small, The parameters of the model of energy conversion and work in the emission channel are , , , , The parameters can be obtained by looking up the table based on the type of charge. , , It can be obtained by the fixed size of the prediction system.

[0144] Furthermore, based on the model of energy conversion and work done in the launch channel, expressions for the internal energy of the charge gas product, the kinetic energy of the projectile, and the kinetic energy of the charge gas product are obtained, namely, formulas (25)-(27). The real-time pressure inside the launch channel after the charge is ignited and the predicted results of the projectile movement speed are substituted into formulas (25)-(27) to obtain the internal energy of the charge gas product, the kinetic energy of the projectile, and the kinetic energy of the charge gas product, respectively.

[0145] Specifically, the internal energy of the charge gas product is expressed as:

[0146] ; (25)

[0147] The kinetic energy of a missile is expressed as:

[0148] ; (26)

[0149] The kinetic energy of the charge gas product is expressed as:

[0150] (27)

[0151] Embodiment 2

[0152] One embodiment of the present invention discloses a transmitting device. Figure 2 As shown, the launch device includes: a restraining body, a laser ignition device, a pressure testing device, a charge, and a projectile;

[0153] The constraint body comprises an inner constraint body and an outer constraint body; a cylindrical first cavity is arranged at the center of the inner constraint body, a plug is arranged at the bottom of the first cavity, and a diaphragm covers the top of the first cavity, so that the first cavity forms a closed chamber, and the charge is located in the closed chamber; a groove is arranged at the upper part of the outer constraint body, and a cylindrical second cavity is arranged at the lower part; the lower part of the inner constraint body is embedded in the groove of the outer constraint body, and the first cavity is aligned with the second cavity along the center line;

[0154] The missile is located at the bottom of the second cavity, the tail of the missile is flush with the bottom of the second cavity and fits tightly with the second cavity, and the second cavity serves as a launch path; the inner and outer restraint bodies are fixed by flange structures;

[0155] The laser ignition device is located above the inner constraint body and is used to emit laser to the charge to ignite the charge by the laser;

[0156] The pressure testing device is located on the side wall of the inner constraint body and is used to measure the pressure in the closed chamber inside the inner constraint body.

[0157] Specifically, the diameter of the first cavity is the same as the diameter of the second cavity. The charge includes ignition powder and gas generating powder; the ignition powder is used to ignite the charge by laser irradiation; the gas generating powder is used to produce gas products by chemical reaction after ignition. The projectile includes a head and a tail; the head is made of steel material and is cylindrical, and the head and tail are connected by threads; the tail is made of nylon material and is a truncated cone structure; Figure 3 As shown, the diameter of the upper bottom surface of the truncated cone structure is smaller than the diameter of the lower bottom surface.

[0158] Furthermore, the laser ignition device includes a control console, a laser probe, a reflector and a sapphire window; the control console is connected to the laser probe and is used to set the power of the emitted laser; the laser probe is used to emit laser to the reflector; the reflector is located above the sapphire window and is used to reflect the incident laser to the sapphire window; the sapphire window is located at the upper end of the plug in the inner constraint body, and a through hole is provided at the center of the plug, and the laser reflected by the reflector passes through the through hole and the sapphire window in sequence and then enters the charge, and the charge is ignited by the laser.

[0159] Furthermore, the pressure testing device includes a pressure sensor, a charge amplifier, an oscilloscope, and a pressure sensor mounting piece; the pressure sensor is mounted on the pressure sensor mounting piece and is connected in series with one end of the charge amplifier to measure the pressure in the closed chamber inside the constraint body; the other end of the charge amplifier is connected in series with the oscilloscope to set the amplification factor to amplify the pressure signal obtained by the pressure sensor; the oscilloscope is used to sample and record the pressure signal amplified by the charge amplifier; the pressure sensor mounting piece is installed with an opening on the side wall of the inner constraint body so that the gas in the closed chamber inside the inner constraint body contacts the pressure sensor.

[0160] Specifically, during implementation, the laser ignites the charge through the sapphire window. After the charge is ignited, it triggers the pressure sensor to start measuring and recording the data of the pressure change in the closed chamber over time. At the same time, the high-temperature and high-pressure gas product produced by the chemical reaction of the charge reaches a stable state, breaks through the diaphragm between the outer constraint body and the inner constraint body, and drives the projectile to move until the projectile moves to the exit of the launch channel, ending the measurement of the pressure sensor.

[0161] It should be noted that the pressure in the closed chamber inside the constraint body in this embodiment is measured, that is, the pressure inside the launch path in Embodiment 1. In this embodiment, the truncated cone structure at the tail of the missile and the diaphragm between the inner and outer constraint bodies ensure the airtightness of the prediction system, thereby preventing the leakage of gas products and energy dissipation, and improving the accuracy of the internal pressure measurement and energy conversion prediction of the system.

[0162] Specifically, the appropriate membrane thickness is selected so that the reaction degree of the charge when the gas product breaks through the membrane is 100%, and this moment is , the corresponding diaphragm punching strength at this moment is:

[0163] , (28)

[0164] in, is the diaphragm punching strength, is the diaphragm punching shear strength, is the diaphragm radius, is the diaphragm thickness.

[0165] It can be understood that the present application not only improves the airtightness of the prediction system by installing a diaphragm between the inner and outer constraints, but also allows the generated gas products to break through the diaphragm and then act on the projectile after stabilization, thereby improving the strength of the force and the stability of the projectile. The present application not only improves the airtightness of the prediction system by using a truncated cone structure at the tail of the projectile, but also allows the gas products to act more evenly on the tail of the projectile, thereby improving the stability of the projectile. The present application uses a pressure sensor mounting part to adapt to different pressure sensors, and there is no need to open holes of different sizes on the prediction system according to the size of different pressure sensors, thereby improving versatility; and it solves the problem that the hole required to directly open a hole to install the pressure sensor on the system is longer, but the actual device cannot meet the hole length requirement.

[0166] Embodiment 3

[0167] The charge mass is changed, and the prediction results of energy conversion in the launch channel and the initial velocity of the projectile under different charge masses are obtained through the model of energy conversion and work done in the launch channel. The influence of charge mass on energy conversion in the launch channel and the initial velocity of the projectile is analyzed by comparing the above prediction results.

[0168] Exemplarily, two charges of different mass are selected, namely, a first charge and a second charge. Both the first charge and the second charge use black powder and the same gas generating agent, wherein the black powder is used as the ignition agent. The first charge uses 0.145g of black powder and 1.841g of gas generating agent, and the second charge uses 0.175g of black powder and 1.247g of gas generating agent. Compared with the first charge, the ignition agent amount of the second charge is increased, and the gas generating agent amount is reduced, and the total mass of the first charge is greater than the total mass of the second charge. The first charge obtains a first real-time pressure inside the closed chamber after charge ignition through the prediction system in Example 2; the first real-time pressure inside the closed chamber is brought into the model of energy conversion and work in the launch channel to obtain a first prediction result of the projectile movement speed and a first prediction result of the projectile initial velocity; the first real-time pressure and the first prediction result of the projectile movement speed are brought into formulas (25)-(27) to respectively obtain a first internal energy of the charge gas product, a first kinetic energy of the projectile, and a first kinetic energy of the charge gas product; similarly, a second real-time pressure inside the closed chamber after charge ignition, a second prediction result of the projectile movement speed, a second prediction result of the projectile initial velocity, a second internal energy of the charge gas product, a second kinetic energy of the projectile, and a second kinetic energy of the charge gas product can be obtained.

[0169] Assume that the heat of combustion of the gas generating agent is The heat of combustion of black powder is , , , The maximum pressure values ​​corresponding to the first charge and the second charge, the predicted results of the initial velocity of the projectile, and the proportion of the projectile kinetic energy are shown in the following table:

[0170]

[0171] The real-time pressures corresponding to the first charge and the second charge are as follows: Figure 4 As shown in the table above, as the amount of charge increases, the total amount of energy released increases, the initial velocity of the projectile increases, but the proportion of the projectile's kinetic energy increases nonlinearly. Figure 4 It can be seen that the gas production amount of the second charge is reduced and the total mass of the charge is reduced, but the mass of the ignition charge is increased. Therefore, the ignition time of the second charge is slower than the ignition time of the first charge, resulting in a slower growth of the pressure corresponding to the second charge. The pressure growth rate will affect the reaction rate of the charge, further resulting in a slower reaction rate of the second charge. Therefore, the rising speed of the second real-time pressure is slower than the rising speed of the first real-time pressure, and the maximum pressure value of the second real-time pressure is less than the maximum pressure value of the first real-time pressure, resulting in a significant reduction in the fluctuation amplitude of the second real-time pressure.

[0172] Compared with the prior art, the method for predicting the energy conversion and external work of a projectile in a launch channel provided by the present invention has the following beneficial effects:

[0173] 1. The present invention brings the function of the internal energy of the charge gas product, the function of the external work done by the constrained charge system and the function of the gas product mass increase rate into the energy and work function in the launch channel to obtain the model of energy conversion and work done in the launch channel, which solves the current problem of unclear formation mechanism and influence of energy conversion and external work done in the launch channel.

[0174] 2. The present invention divides the process of energy conversion and work done by the projectile in the launch channel into a first process and a second process. According to the difference in the mass of the gas products in the two processes, a model of energy conversion and work done in the launch channel corresponding to the first process and the second process is obtained, and the prediction results of the energy conversion of the projectile in the launch channel and the initial velocity of the projectile are obtained according to the real-time pressure and the model, thereby improving the accuracy of the prediction results of the energy conversion in the launch channel and the initial velocity of the projectile.

[0175] 3. The present invention provides a theoretical basis for evaluating the loss of energy conversion of a projectile in a launch channel by establishing a model of energy conversion and work done in a launch channel and a charge reactivity model.

[0176] 4. The present invention not only improves the airtightness of the prediction system by installing a diaphragm between the inner and outer constraints, but also allows the generated gas products to break through the diaphragm and then act on the projectile after stabilization, thereby improving the strength of the force and the stability of the projectile. The present invention not only improves the airtightness of the prediction system by using the truncated cone structure at the tail of the projectile, but also allows the gas products to act more evenly on the tail of the projectile, thereby improving the stability of the projectile. The present invention adapts different pressure sensors through the pressure sensor mounting part, and there is no need to open holes of different sizes on the prediction system according to the size of different pressure sensors, thereby improving versatility; and it solves the problem that the hole required to directly open the pressure sensor on the system needs to be longer, but the actual device cannot meet the hole length requirement.

[0177] Those skilled in the art will appreciate that all or part of the processes of the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, wherein the computer-readable storage medium is a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0178] The above description is only a preferred specific implementation manner 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 any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for predicting the energy conversion and external work of a projectile in a launch channel, characterized in that: The method comprises the following steps: Based on the laws of thermodynamics and the ideal gas state equation, a function of the internal energy of the charge gas product in the constrained charge system is established; based on fluid mechanics and the Lagrangian method, a function of the kinetic energy of the charge gas product is established, and based on the function of the kinetic energy of the projectile and the kinetic energy of the gas product, a function of the external work done by the constrained charge system is established; based on Vielle's law, a function of the rate of increase of the mass of the gas product is obtained; based on the law of conservation of energy and interior ballistics, a function of energy and work in the launch channel is established, and the function of the internal energy of the charge gas product, the function of the external work done by the constrained charge system, and the function of the rate of increase of the mass of the gas product are brought into the energy and work function in the launch channel to obtain a model of energy conversion and work done in the launch channel; The process of energy conversion and work-doing of the projectile in the launch channel is divided into a first process and a second process. The starting time of the first process is the ignition time of the ignition device, and the ending time is the time when the charge reaction is completed; the starting time of the second process is the time when the charge reaction is completed, and the ending time is the time when the projectile reaches the exit of the launch channel; The models of energy conversion and work done in the emission channel corresponding to the first process and the second process are: ， in, is the energy released per unit mass of charge, is the burning rate coefficient, is the density of the solid charge, is the cross-sectional area of ​​the solid charge column, is the ignition timing of the ignition device, is the burning rate pressure index, is the internal pressure of the launch channel, To absorb the energy input from the outside for the charge, is the mass of the gas product, is the initial volume of space between the charge and the projectile, is the mass of the projectile, is the projectile speed, is the cross-sectional area of ​​the launch channel, is the adiabatic index, In order to limit the heat exchanged between the charge system and the outside world, The moment when the charge reaction is completed. is the time when the missile reaches the exit of the launch track; The real-time pressure inside the launch channel after the charge is ignited is obtained through the pressure sensor of the launch device, and the real-time pressure inside the launch channel is brought into the model of energy conversion and work in the launch channel to obtain the prediction result of the movement speed of the projectile; when When the initial velocity of the projectile is calculated, the predicted result of the energy conversion of the projectile in the launch channel includes the internal energy of the charge gas product, the kinetic energy of the projectile, and the kinetic energy of the charge gas product; the initial velocity of the projectile is the velocity of the projectile when it leaves the exit of the launch channel.

2. The method for predicting energy conversion and external work of a projectile in a launch channel according to claim 1, characterized in that: The launching device comprises: a restraining body, a laser ignition device, a pressure testing device, a charge, and a projectile; The constraint body comprises an inner constraint body and an outer constraint body; a cylindrical first cavity is arranged at the center of the inner constraint body, a plug is arranged at the bottom of the first cavity, and a diaphragm covers the top of the first cavity, so that the first cavity forms a closed chamber, and the charge is located in the closed chamber; a groove is arranged at the upper part of the outer constraint body, and a cylindrical second cavity is arranged at the lower part; the lower part of the inner constraint body is embedded in the groove of the outer constraint body, and the first cavity is aligned with the second cavity along the center line; The missile is located at the bottom of the second cavity, the tail of the missile is flush with the bottom of the second cavity and fits tightly with the second cavity, and the second cavity serves as a launch path; the inner and outer restraint bodies are fixed by flange structures; The laser ignition device is located above the inner constraint body and is used to emit laser to the charge to ignite the charge by the laser; The pressure testing device is located on the side wall of the inner constraint body and is used to measure the pressure in the closed chamber inside the inner constraint body.

3. The method for predicting energy conversion and external work of a projectile in a launch channel according to claim 1, characterized in that: Based on the model of energy conversion and work in the launch channel, expressions for the internal energy of the charge gas product, the kinetic energy of the projectile, and the kinetic energy of the charge gas product are obtained, namely, formulas (1)-(3). The real-time pressure inside the launch channel after the charge is ignited and the predicted results of the projectile movement speed are substituted into formulas (1)-(3) to obtain the internal energy of the charge gas product, the kinetic energy of the projectile, and the kinetic energy of the charge gas product respectively. The internal energy of the charge gas product is expressed as: ， (1) in, is the internal energy of the charge gas product, is the internal pressure of the launch channel, is the initial volume of space between the charge and the projectile, is the cross-sectional area of ​​the launch channel, is the ignition timing of the ignition device, is the projectile speed, is the adiabatic index; The kinetic energy of a missile is expressed as: ， (2) in, is the kinetic energy of the missile, is the mass of the missile; The kinetic energy of the charge gas product is expressed as: ， (3) in, is the kinetic energy of the charge gas product, is the mass of the gas product.

4. The method for predicting energy conversion and external work of a projectile in a launch path according to claim 2, characterized in that: The laser ignition device includes a control console, a laser probe, a reflector and a sapphire window; the control console is connected to the laser probe and is used to set the power of the emitted laser; the laser probe is used to emit laser to the reflector; the reflector is located above the sapphire window and is used to reflect the incident laser to the sapphire window; the sapphire window is located at the upper end of the plug in the inner constraint body, and a through hole is provided at the center of the plug, and the laser reflected by the reflector passes through the through hole and the sapphire window in sequence and then enters the charge, and the charge is ignited by the laser.

5. The method for predicting energy conversion and external work of a projectile in a launch path according to claim 2, characterized in that: The pressure testing device includes a pressure sensor, a charge amplifier, an oscilloscope, and a pressure sensor mounting piece; the pressure sensor is mounted on the pressure sensor mounting piece and is connected in series with one end of the charge amplifier to measure the pressure in the closed chamber inside the constraint body; the other end of the charge amplifier is connected in series with the oscilloscope to set the amplification factor to amplify the pressure signal obtained by the pressure sensor; the oscilloscope is used to sample and record the pressure signal amplified by the charge amplifier; the pressure sensor mounting piece has an opening installed on the side wall of the inner constraint body so that the gas in the closed chamber inside the inner constraint body contacts the pressure sensor.

6. The method for predicting energy conversion and external work of a projectile in a launch channel according to claim 1, characterized in that: The function of the gas product mass increase rate is: ， in, is the rate of increase of gas product mass, is the density of the solid charge, is the cross-sectional area of ​​the solid charge column, is the burning rate of the charge, i.e., the rate of combustion; It is expressed as: ， in, is the burning rate coefficient, is the burning rate pressure index, is the internal pressure of the launch channel.

7. The method for predicting energy conversion and external work of a projectile in a launch channel according to claim 1, characterized in that: The energy and work function in the emission channel are: ， in, It is the sum of the chemical energy generated by the combustion of the charge and the energy absorbed by the charge from the outside. is the internal energy of the charge gas product, In order to limit the heat exchanged between the charge system and the outside world, To constrain the charge system to do work externally; It is expressed as: ， in, is the energy released per unit mass of charge, is the ignition timing of the ignition device, is the rate of increase of gas product mass, To absorb the energy input from the outside for the charge.

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