System and method for calculating shooting speed of two-stage light-gas cannonball

Abstract

The invention relates to a system and a method for calculating the shot launching speed of a light-gas shell, in particular to a system and a method for calculating the shot launching speed of a secondary light-gas shell, and solves the problem that calculation is difficult to quickly complete on a test site by adopting an existing method. The method comprises the following steps that 1, a system is built, and light gas and high-pressure gas are injected; 2, analyzing the energy transfer process of launching the projectile, and calculating the projectile launching speed based on the law of conservation of energy; 3, the actual launching speed of the projectile is obtained; 4, subtracting the calculated projectile launching speed from the actual projectile launching speed, and judging whether the absolute value of the difference value is smaller than or equal to a preset error threshold value or not; if yes, executing the step 5; if not, executing the step 6; 5, recording parameter values, and executing the step 7; step 6, correcting and recording parameter values; and 7, subsequently using the recorded parameter values, and calculating the projectile launching speed by adopting the method in the step 2.

Description

Technical Field

[0001] The present invention relates to a system and method for calculating the launch speed of a light gas cannon projectile, and in particular to a system and method for calculating the launch speed of a two-stage light gas cannon projectile. Background Art

[0002] Calculation of projectile launch velocity before the two-stage light gas gun test is a necessary task for the two-stage light gas gun test.

[0003] The process of launching a two-stage light gas cannon projectile involves complex motion behavior conversion, specifically: before the projectile moves in the launch tube, it includes motion behaviors such as the opening of the high-pressure gas source chamber valve, the movement of the piston into the cone, and the compression of the light gas. When the projectile starts to move in the launch tube, it includes motion behaviors such as the rupture of the small diaphragm, the cessation of the piston movement, and the projectile leaving the barrel. Therefore, the calculation of the launch speed of the two-stage light gas cannon projectile involves the analysis and calculation of multiple motion processes. In order to calculate the launch speed of the two-stage light gas cannon projectile, the existing technology usually adopts a simulation calculation method based on finite elements, or a numerical calculation method based on mathematical models. However, the calculation process of these calculation methods is relatively complicated, and the technical ability of the calculation personnel is also very high. Under the commonly used conventional computing resources, the calculation time is long, and it is difficult to complete the calculation quickly at the test site, which makes it difficult to make real-time corrections on site according to the debugging test results, and it is impossible to quickly estimate and adjust parameters on site to guide the implementation of the test.

[0004] Therefore, it is urgent to develop a method that can easily and quickly calculate the launch velocity of the two-stage light gas cannon projectile, so as to meet the test needs of the two-stage light gas cannon test, which requires real-time correction based on the debugging test results, rapid on-site estimation and parameter adjustment, and guidance of the test implementation. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problems that when using the existing calculation method to calculate the firing speed of a two-stage light gas cannon projectile, the calculation process is complicated, the technical ability requirements of the calculation personnel are high, the calculation time is long, it is difficult to complete the calculation quickly at the test site, and it is difficult to meet the technical problems of the two-stage light gas cannon test that requires real-time corrections on site according to the debugging test results, rapid estimation and parameter adjustment on site, and guidance of the test implementation. A system and method for calculating the firing speed of a two-stage light gas cannon projectile are provided.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A system for calculating the velocity of a two-stage light gas cannon projectile, the particularities of which are:

[0008] Includes a two-stage light gas gun projectile loading system and data acquisition system;

[0009] The two-stage light gas gun projectile loading system comprises a gas source chamber, a pump pipe, a high-pressure cone section and a launch tube which are coaxially and sealedly connected in sequence from back to front;

[0010] The gas source chamber is used to store high-pressure gas for launch; a large diaphragm is provided at one end of the gas source chamber connected to the pump tube, which is used to separate the gas source chamber from the inner cavity of the pump tube before launch;

[0011] A piston is arranged in the inner cavity of the pump tube; a small diaphragm is arranged at the end where the high-pressure cone section is connected to the launch tube, which is used to separate the high-pressure cone section from the inner cavity of the launch tube before launching; the pump tube and the inner cavity of the high-pressure cone section between the piston and the small diaphragm are filled with light gas;

[0012] The inner cavity of the launch tube is used to install the projectile to be launched, and the projectile outlet end at the front end is the muzzle;

[0013] During firing, the high-pressure gas penetrates the large diaphragm, pushing the piston forward to compress the light gas, and the compressed light gas penetrates the small diaphragm, pushing the projectile to be fired forward to fire it;

[0014] The data acquisition system includes a ruler and a high-speed camera;

[0015] The scale is arranged on the ballistic line of the two-stage light gas gun projectile loading system;

[0016] The high-speed camera is used to photograph and record the information of the scale set on the ballistic line before launching the projectile, and photograph and record the flight trajectory of the projectile when launching the projectile, so as to convert the two to obtain the actual launching speed of the projectile.

[0017] Furthermore, the high-pressure gas refers to a gas having a pressure greater than or equal to 1 MPa;

[0018] The light gas is hydrogen or helium.

[0019] Furthermore, the high-speed camera refers to a camera that can capture images at a speed of more than one thousand frames per second.

[0020] Furthermore, in order to enable the high-speed camera to automatically and in real time shoot and record the flight trajectory of the projectile, the data acquisition system also includes a target box, a laser transmitter, a laser receiver, a photoelectric converter, an oscilloscope and a fill light source;

[0021] The target box is arranged at the front end side of the launch tube, and the front end of the launch tube extends into the target box; two groups of observation windows arranged in the front-to-back direction are symmetrically arranged on the left and right sides of the target box, and one group of observation windows close to the rear end side is defined as the rear end observation window, and the other group is defined as the front end observation window;

[0022] The laser transmitter and the laser receiver are coaxially arranged, and are respectively located on the left and right sides of the exterior of the target box corresponding to the position of the rear end observation window;

[0023] The input end of the laser receiver is used to receive the laser emitted by the laser transmitter; the output end of the laser receiver is connected to the high-speed camera through the photoelectric converter and the oscilloscope in sequence, and is used to send a signal to the oscilloscope through the photoelectric converter when the laser emitted by the laser transmitter is blocked by the emitted projectile, and trigger the high-speed camera through the oscilloscope to shoot and record the flight trajectory of the projectile;

[0024] The fill light source and the high-speed camera are respectively located on the left and right sides of the target box outside corresponding to the position of the front observation window; a shading paper is arranged on the front observation window on the side where the fill light source is located; the fill light source is used to fill light for the high-speed camera.

[0025] At the same time, the present invention also provides a method for calculating the launch speed of a two-stage light gas cannon projectile, which is special in that it includes the following steps:

[0026] Step 1: Build the above-mentioned system for calculating the projectile launch velocity of the two-stage light gas cannon, and inject light gas of the design required pressure into the pump tube between the piston and the small diaphragm and the inner cavity of the high-pressure cone section, and inject high-pressure gas of the design required pressure into the inner cavity of the gas source chamber;

[0027] Step 2: In the system for calculating the firing speed of the two-stage light gas cannon projectile built in step 1 and having completed the injection of light gas and high-pressure gas, the process of firing the projectile by the two-stage light gas cannon projectile loading system is converted into an energy transfer process of energy conversion and consumption, the energy transfer process in the process of firing the projectile is analyzed, and based on the law of conservation of energy and the given relevant parameters, the projectile firing speed is calculated; the relevant parameters include the friction coefficient μ between the piston and the pump tube f1 , the friction coefficient between the projectile and the launch tube μ f2 And the leakage coefficient k s ;

[0028] Step 3: sequentially start the data acquisition system and the secondary light gas cannon projectile loading system in the system for calculating the secondary light gas cannon projectile firing speed, which are built in step 1 and have completed the injection of light gas and high-pressure gas, to obtain the actual projectile firing speed;

[0029] Step 4: Subtract the projectile launch speed calculated in step 2 from the actual projectile launch speed obtained in step 3, and determine whether the absolute value of the difference between the two is less than or equal to a preset error threshold; if so, execute step 5; if not, execute step 6;

[0030] Step 5: Record the relevant parameter values ​​given in step 2, and then proceed to step 7;

[0031] Step 6: Correct the relevant parameter values ​​given in step 2, and record the corrected relevant parameter values;

[0032] Step 7: Subsequently, the given relevant parameter values ​​recorded are used in the same way as in step 2 to calculate the projectile launch speed and complete the calculation.

[0033] Further, the pressure of the light gas in the inner cavity of the pump tube and the high-pressure cone section when the light gas injection is just completed in step 1 is recorded as the light gas initial pressure P h1 When the high-pressure gas injection is just completed in step 1, the pressure of the high-pressure gas in the gas source chamber is recorded as the initial pressure of the high-pressure gas P g1 ;

[0034] The step 2 is specifically as follows:

[0035] Step 2.1: In the system for calculating the firing speed of the two-stage light gas cannon projectile built in step 1 and into which the light gas and high-pressure gas have been injected, the process of firing the projectile by the two-stage light gas cannon projectile loading system is converted into an energy transfer process of energy conversion and consumption, and the energy transfer process in the process of firing the projectile is analyzed;

[0036] Step 2.2: In the system for calculating the firing speed of the secondary light gas cannon projectile built in step 1 and having completed the injection of light gas and high pressure gas, the structural parameters of the secondary light gas cannon projectile loading system, the initial pressure P of the light gas h1 , the initial pressure P of the high pressure gas g1 As well as the analysis results of step 2.1, based on the laws of thermodynamics and the law of conservation of energy, the energy equation is constructed;

[0037] Step 2.3: According to the energy equation constructed in step 2.2, the projectile launch speed is calculated.

[0038] Furthermore, the analysis result of analyzing the energy transfer process during the projectile launch process described in step 2.1 is:

[0039] The energy source for launching the projectile is: the energy W of the high-pressure gas injected into the gas source chamber in step 1 g ;

[0040] The energy consumption in the process of launching the projectile includes: the energy consumption of the light gas doing work W h , the energy consumption W of the friction between the piston and the pump tube and between the projectile and the launch tube f , the energy consumption W of the piston entering the conep , Energy consumption of gas leakage W s And the projectile kinetic energy consumption E k ;

[0041] The E k is a mathematical formula containing the desired quantity, the projectile launch velocity;

[0042] The energy equation constructed in step 2.2 is:

[0043] W g =W h +W f +W p +W s +E k .

[0044] Furthermore, in the energy equation constructed in step 2.2, the energy W of the high-pressure gas doing work g for:

[0045]

[0046] Where: V g1 γ represents that when the high-pressure gas injection is just completed in step 1, the volume of the high-pressure gas in the inner cavity of the gas source chamber, that is, the initial volume of the high-pressure gas, is equal to the volume of the inner cavity of the gas source chamber; g Represents the high-pressure gas adiabatic coefficient; V g2 represents the volume of high-pressure gas in the terminal state, where the piston stops moving and the projectile has flown out of the muzzle. g2 Approximately:

[0047] V g2 =V g1 +πD 2 L / 4;

[0048] Where: D represents the inner diameter of the pump tube; L represents the length of the pump tube;

[0049] In the energy equation constructed in step 2.2, the energy consumption of the light gas doing work is W h for:

[0050]

[0051] Where: V h1 It represents the volume of light gas in the inner cavity of the pump tube and the high-pressure cone section when the light gas injection is just completed in step 1, that is, the initial volume of light gas, which is approximately V h1 =πD 2 L / 4; γ h Represents the light gas adiabatic coefficient; V h2represents the volume of light gas at the terminal state, which is approximately Where D h Indicates the inner diameter of the launch tube, L f Indicates the length of the launch tube;

[0052] In the energy equation constructed in step 2.2, the energy consumption W of the friction between the piston and the pump tube and between the projectile and the launch tube is f for:

[0053] W f =μ f1 σ y1 (πDL f1 )L+μ f2 σ y2 (πD h L f2 )L f ;

[0054] Where: μ f1 Indicates the friction coefficient between the piston and the pump tube; σ y1 Indicates piston yield strength; L f1 Indicates the length of the piston; μ f2 Represents the friction coefficient between the projectile and the launch tube; σ y2 Indicates the yield strength of the projectile; L f2 Indicates the length of the projectile;

[0055] In the energy equation constructed in step 2.2, the energy consumption of the piston entering the cone is W p for:

[0056]

[0057] Where: D bottom Indicates the original diameter of the piston when it is not deformed; D top Indicates the diameter of the front end of the piston in the terminal state. It is an empirical value and is taken as 0.2D bottom ~0.95D bottom ; S1 represents the original cross-sectional area of ​​the piston when it is not deformed; L p Indicates the depth of the piston front end into the cone, which is an empirical value;

[0058] In the energy equation constructed in step 2.2, the energy consumption of the gas leakage is W S for:

[0059]

[0060] Where: k s Indicates the leakage coefficient, which is an empirical value; v d Indicates the projectile launch speed;

[0061] In the energy equation constructed in step 2.2, the kinetic energy consumption of the projectile is E k for:

[0062]

[0063] Where: m d Indicates the mass of the projectile.

[0064] Furthermore, the step 3 is specifically as follows:

[0065] Step 3.1: Start the data acquisition system in the system for calculating the firing speed of the two-stage light gas cannon projectile, which has been built in step 1 and has completed the injection of light gas and high-pressure gas, and use a high-speed camera to shoot and record the information of the ruler set on the ballistic line. After shooting, remove the ruler from the ballistic line;

[0066] Step 3.2: Start the secondary light gas cannon projectile loading system in the system for calculating the firing speed of secondary light gas cannon projectiles which has been built in step 1 and has completed the injection of light gas and high-pressure gas, and fire the projectile installed in the launch tube. During the process of firing the projectile, trigger the high-speed camera to shoot and record the flight trajectory of the projectile;

[0067] Step 3.3: According to the information of the scale recorded by the high-speed camera in step 3.1 and the flight trajectory of the projectile recorded by the high-speed camera in step 3.2, the actual launch speed of the projectile is calculated.

[0068] Furthermore, in step 3.3, according to the information of the scale recorded by the high-speed camera in step 3.1 and the flight trajectory of the projectile recorded by the high-speed camera in step 3.2, the actual launch speed of the projectile is converted by the following formula:

[0069]

[0070] Where: v s represents the actual launch speed of the projectile; l represents the actual spacing selected from the information of the ruler recorded by the high-speed camera in step 3.1; δx cam represents the spacing of image pixels under the actual spacing l selected; δx s , δt represent the selected projectile flight distance interval and the time taken by the projectile to fly this distance interval on the flight trajectory of the projectile recorded by the high-speed camera in step 3.2, respectively.

[0071] The beneficial effects of the present invention are:

[0072] (1) In the method for calculating the projectile launch speed of a two-stage light-gas cannon projectile of the present invention, a two-stage light-gas cannon projectile loading system is constructed from the perspective of energy. The process of projectile launch by the two-stage light-gas cannon projectile loading system is converted into an energy transfer process of energy conversion and consumption, and the energy transfer process in the projectile launch process is analyzed. Based on the law of conservation of energy, the projectile launch speed is calculated. When calculating, it is only necessary to know the initial pressure P of the light gas injected into the inner cavity of the pump tube and the high-pressure cone section between the piston and the small diaphragm. h1 , the initial pressure P of the high-pressure gas injected into the gas source chamber g1 and the structural parameters of the two-stage light-gas cannon projectile loading system, the projectile launch speed can be calculated; it lowers the threshold of internal ballistic calculation, the calculation process is simple, the technical ability requirements of the calculation personnel are also low, the dependence on the high-speed computing ability of the computer is reduced, and the calculation can be quickly completed at the field test site under the commonly used conventional computing resources, and the real-time correction can be made on site according to the debugging test results, and the on-site rapid estimation and parameter adjustment can be made to guide the implementation of the test, which can meet the needs of field engineering applications; therefore, the present invention solves the technical problems that when the existing calculation method is used to calculate the projectile launch speed of the two-stage light-gas cannon, the calculation process is complex, the technical ability requirements of the calculation personnel are high, the calculation time is long, it is difficult to quickly complete the calculation at the test site, and it is difficult to meet the test requirements of the two-stage light-gas cannon test that the real-time correction can be made on site according to the debugging test results, the on-site rapid estimation and parameter adjustment can be made, and the implementation of the test can be guided.

[0073] (2) In the method for calculating the firing speed of a two-stage light-gas cannon projectile of the present invention, the process of firing a projectile by a two-stage light-gas cannon projectile loading system is converted into an energy transfer process of energy conversion and consumption. By analyzing the energy transfer process in the process of firing the projectile, based on the laws of thermodynamics and the law of conservation of energy, an energy equation for the process of firing a projectile by a two-stage light-gas cannon is constructed. The projectile firing speed is calculated by the energy equation, thereby realizing the application of the law of conservation of energy in the calculation of the firing speed of a two-stage light-gas cannon projectile. It not only simplifies the calculation flow and process of the firing speed of a two-stage light-gas cannon projectile and improves the convenience of calculation, but also can more vividly describe the physical process of firing a projectile by a two-stage light-gas cannon, improves the diversity of the internal ballistic analysis of a two-stage light-gas cannon, and can be expanded to be applied to the calculation of the firing speed of two-stage light-gas cannon projectiles loaded in various ways.

[0074] (3) The method for calculating the projectile launching speed of a two-stage light gas cannon according to the present invention can calculate the projectile launching speed more accurately by using the law of conservation of energy and clarifying the energy consumption of each link in the process of projectile launching by the two-stage light gas cannon. The method can be used to reversely set and correct the gas injection parameters of the gas source chamber and the parameters for injecting light gas into the inner cavity of the pump tube between the piston and the small diaphragm and the high-pressure cone section before the two-stage light gas cannon launch test, so as to guide the two-stage light gas cannon launch test.

[0075] (4) The method for calculating the projectile launch velocity of a two-stage light gas cannon according to the present invention can not only calculate the projectile launch velocity, but also include verification of the calculated projectile launch velocity; when the error between the calculated projectile launch velocity and the actual projectile launch velocity is too large and exceeds a preset error threshold, the relevant parameter values ​​given in the process of calculating the projectile launch velocity are corrected and recorded for subsequent calculation of the projectile launch velocity; it can make the projectile launch velocity calculated before subsequent tests more accurate, and thus can accurately estimate, adjust parameters, and guide the implementation of the test.

[0076] (5) The data acquisition system provided in the system for calculating the firing speed of a two-stage light gas cannon projectile of the present invention can automatically trigger a high-speed camera to capture and record the flight trajectory of the projectile in real time during the process of firing the projectile, thereby improving the convenience and real-time performance of data acquisition, and furthermore, can conveniently obtain the actual firing speed of the projectile, and the obtained actual firing speed of the projectile is also more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 It is a structural schematic diagram of a two-stage light-gas cannon projectile loading system in an embodiment of the system for calculating the firing speed of a two-stage light-gas cannon projectile of the present invention;

[0078] Figure 2 It is a structural schematic diagram of a data acquisition system in an embodiment of the system for calculating the firing speed of a two-stage light gas cannon projectile of the present invention;

[0079] Figure 3 The present invention is a flow chart of a method for calculating the launch velocity of a two-stage light gas cannon projectile according to an embodiment of the present invention.

[0080] The descriptions of the numbers in the figure are as follows:

[0081] 01-gas source chamber, 02-pump tube, 03-high-pressure cone section, 04-launching tube, 05-large diaphragm, 06-piston, 07-small diaphragm, 08-projectile, 1-target box, 101-rear end observation window, 102-front end observation window, 2-laser transmitter, 3-laser receiver, 4-photoelectric converter, 5-oscilloscope, 6-high-speed camera, 7-ruler, 8-fill light source, 9-shading paper. DETAILED DESCRIPTION

[0082] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0083] See also Figure 1 and Figure 2 , a system for calculating the launch speed of a two-stage light gas gun projectile, including a two-stage light gas gun projectile loading system and a data acquisition system.

[0084] See also Figure 1 The above-mentioned two-stage light gas cannon projectile loading system includes a gas source chamber 01, a pump pipe 02, a high-pressure cone section 03 and a launch tube 04 which are coaxially sealed and connected in sequence from back to front; the gas source chamber 01 is used to store high-pressure gas for launch; a large diaphragm 05 is provided at one end of the gas source chamber 01 connected to the pump pipe 02, which is used to separate the gas source chamber 01 from the inner cavity of the pump pipe 02 before launch; a piston 06 is provided in the inner cavity of the pump pipe 02; a small diaphragm 07 is provided at one end of the high-pressure cone section 03 connected to the launch tube 04 , used to separate the high-pressure cone section 03 from the inner cavity of the launch tube 04 before launching; the pump tube 02 between the piston 06 and the small diaphragm 07 and the inner cavity of the high-pressure cone section 03 are filled with light gas; the inner cavity of the launch tube 04 is used to install the projectile 08 to be launched, and the frontmost projectile outlet end is the muzzle; during launching, the high-pressure gas penetrates the large diaphragm 05, pushing the piston 06 to move forward to compress the light gas, and the compressed light gas penetrates the small diaphragm 07, pushing the projectile 08 to be launched to move forward and launch it.

[0085] See also Figure 2, the data acquisition system includes a ruler 7 and a high-speed camera 6. In this embodiment, in order to automatically trigger the high-speed camera 6 to capture and record the flight trajectory of the projectile in real time during the process of launching the projectile, thereby improving the convenience and real-time performance of data acquisition, the data acquisition system preferably includes a target box 1, a laser transmitter 2, a laser receiver 3, a photoelectric converter 4, an oscilloscope 5, and a fill light source 8 in addition to the ruler 7 and the high-speed camera 6. The target box 1 is arranged at the front end side of the launch tube 04, and the front end of the launch tube 04 extends into the target box 1; two groups of observation windows arranged in the front-to-back direction are symmetrically arranged on the left and right side surfaces of the target box 1, and one group of observation windows close to the rear end side is defined as the rear end observation window 101, and the other group is defined as the front end observation window 102; the laser transmitter 2 and the laser receiver 3 are coaxially arranged, and the two are respectively located on the left and right sides of the outside of the target box 1 corresponding to the position of the rear end observation window 101; the input end of the laser receiver 3 is used to receive the laser emitted by the laser transmitter 2; the output end of the laser receiver 3 is connected to the high-speed camera 6 through the above-mentioned photoelectric converter 4, the oscilloscope 5 and the high-speed camera 6 in sequence, and is used when the laser emitted by the laser transmitter 2 is affected by the emitted projectile When the projectile 08 is blocked, a signal is sent to the oscilloscope 5 through the photoelectric converter 4, and the high-speed camera 6 is triggered by the oscilloscope 5 to shoot and record the flight trajectory of the projectile 08; the above-mentioned fill light source 8 and the high-speed camera 6 are respectively located on the left and right sides of the target box 1 corresponding to the position of the above-mentioned front observation window 102; a shading paper 9 is set on the front observation window 102 on the side where the fill light source 8 is located; the fill light source 8 is used to fill light for the high-speed camera 6; the above-mentioned scale 7 is set on the ballistic line of the secondary light gas gun projectile loading system; in addition to shooting and recording the flight trajectory of the projectile 08, the high-speed camera 6 is also used to shoot and record the information of the above-mentioned scale 7 set on the ballistic line before launching the projectile 08, so as to obtain the actual launch speed of the projectile based on the conversion of the two. In order to shoot more clearly, the high-speed camera 6 used in this embodiment can capture images at a speed of more than 1,000 frames per second.

[0086] Also, see Figure 3 The present invention also provides a method for calculating the launch velocity of a two-stage light gas cannon projectile, comprising the following steps:

[0087] Step 1: Build the above-mentioned system for calculating the projectile launch velocity of the two-stage light gas cannon, and inject the light gas of the design required pressure into the inner cavity of the pump tube 02 and the high-pressure cone section 03 between the piston 06 and the small diaphragm 07, and inject the high-pressure gas of the design required pressure into the inner cavity of the gas source chamber 01; specifically:

[0088] Step 1.1: Open and close the chamber of the second-stage light gas gun;

[0089] Remove the connecting bolts between the gas source chamber 01 and the pump pipe 02 of the second-stage light gas gun, loosen the contact surface between the pump pipe 02 and the gas source chamber 01, place the piston 06 at the mouth of the pump pipe 02, and then close the chamber, that is, use bolts to tightly connect the gas source chamber 01 and the pump pipe 02;

[0090] Step 1.2: Inject light gas of the required design pressure into the inner cavity of the pump tube 02 and the high-pressure cone section 03 between the piston 06 and the small diaphragm 07;

[0091] Close the valve between the gas source chamber 01 and the pump tube 02, and inject the light gas of the design required pressure into the inner cavity of the pump tube 02 and the high-pressure cone section 03 between the piston 06 and the small diaphragm 07 through the gas injection valve on the pump tube 02. After the injection is completed, close the gas injection valve; the pressure of the light gas in the inner cavity of the pump tube 02 and the high-pressure cone section 03 when the light gas injection is just completed is recorded as the light gas initial pressure P h1 ;P h1 The range is usually between 0MPa and 1MPa, which is set according to the required projectile launch speed and launch parameters; the injected light gas is usually hydrogen or helium;

[0092] Step 1.3: Inject high-pressure gas of the required design pressure into the inner cavity of the gas source chamber 01;

[0093] Inject high-pressure gas of the required pressure into the inner cavity of the gas source chamber 01, and close the gas injection valve after the injection is completed; the pressure of the high-pressure gas in the inner cavity of the gas source chamber 01 when the high-pressure gas injection is just completed is recorded as the initial pressure of the high-pressure gas P g1 ; The above-mentioned high-pressure gas generally refers to a gas with a pressure greater than or equal to 1MPa; P g1 The range is usually between 1MPa and 150MPa, and is set according to the required projectile launch speed;

[0094] In this embodiment, the inner volume of the gas source chamber 01, that is, the initial volume of the high-pressure gas V g1 The initial pressure of the high pressure gas is 4 liters. g1 is 81MPa, the inner diameter D of the pump tube 02 is 57mm, the length L of the pump tube 02 is 12m, the length of the high-pressure cone section 03 is 120mm, the angle is 10.5°, and the inner diameter D of the launch tube 04 is h is 12.7 mm, the length L of the launch tube 04 f The piston 06 is composed of a polyethylene front end, a middle metal counterweight and a polyethylene rear end. The front end and the rear end of the piston 06 are both interference fit with the pump tube 02. Usually, the outer diameters of the front end and the rear end of the piston 06 are 0.1 mm larger than the inner diameter D of the pump tube 02. In this embodiment, the outer diameters of the front end and the rear end of the piston 06, i.e., the original diameter D of the piston 06 when it is not deformed, are as follows:bottom is 57.1mm, the weight of the piston is 2.7kg, and the length of the piston 06 is L f1 is 20cm, the initial pressure of the light gas is P h1 is 0.3MPa, the length of the projectile 08 is L f2 10mm, projectile mass 08m d 5g;

[0095] Step 2: In the system for calculating the firing speed of the secondary light gas cannon projectile built in step 1 and having completed the injection of light gas and high-pressure gas, the process of firing the projectile 08 by the secondary light gas cannon projectile loading system is converted into an energy transfer process of energy conversion and consumption, and the energy transfer process in the process of firing the projectile 08 is analyzed. Based on the law of conservation of energy and according to the given relevant parameters, the projectile firing speed is calculated; the above-mentioned relevant parameters include the friction coefficient μ between the piston 06 and the pump tube 02 f1 , the friction coefficient μ between the projectile 08 and the launch tube 04 f2 And the leakage coefficient k s ; Specifically:

[0096] Step 2.1: In the system for calculating the firing speed of the secondary light gas cannon projectile built in step 1 and having completed the injection of light gas and high-pressure gas, the process of firing the projectile 08 by the secondary light gas cannon projectile loading system is converted into an energy transfer process of energy conversion and consumption, and the energy transfer process in the process of firing the projectile 08 is analyzed; through the analysis, it can be known that:

[0097] The energy source for launching the projectile 08 is: the energy W of the high-pressure gas injected into the inner cavity of the gas source chamber 01 in step 1 g ;

[0098] The energy consumption in the process of launching the projectile 08 includes: the energy consumption of the light gas doing work W h , the energy consumption W of the friction between the piston 06 and the pump tube 02 and between the projectile 08 and the launch tube 04 f 、Energy consumption W of piston 06 entering cone p , Energy consumption of gas leakage W s And the projectile kinetic energy consumption E k ; The above E k is a mathematical formula containing the desired quantity, the projectile launch velocity;

[0099] Step 2.2: In the system for calculating the launch velocity of the second-stage light gas cannon projectile built in step 1 and having completed the injection of light gas and high-pressure gas, the structural parameters of the second-stage light gas cannon projectile loading system, the initial pressure P of the light gas mentioned above, h1 、The initial pressure P of the high pressure gas g1As well as the analysis results of step 2.1, based on the laws of thermodynamics and the law of conservation of energy, the energy equation is constructed;

[0100] According to the laws of thermodynamics, the above W g , W h , W f , W p , W s and E k The specific calculation process is as follows:

[0101] (1) The energy W of high pressure gas doing work g

[0102] When the projectile 08 is launched, the airtight valve of the gas source chamber 01 is opened, and the high-pressure gas injected into the gas source chamber 01 pushes the piston 06 to move in the pump tube 02. The movement process is set as an adiabatic process. It is known that the adiabatic coefficient of the high-pressure gas is γ g The inner diameter of the pump tube 02 is D, the length of the pump tube 02 is L, and in the terminal state, that is, the piston 06 stops moving and the projectile 08 has flown out of the muzzle, the volume of the high-pressure gas V g2 Approximately:

[0103] V g2 =V g1 +πD 2 L / 4;

[0104] Then, according to the adiabatic process gas state equation:

[0105]

[0106] Where: V g1 P represents the volume of the high-pressure gas in the inner cavity of the gas source chamber 01 when the high-pressure gas injection is just completed in step 1, that is, the initial volume of the high-pressure gas, which is equal to the volume of the inner cavity of the gas source chamber 01; g2 is the pressure of the high-pressure gas in the terminal state; according to the above formula, the pressure of the high-pressure gas in the terminal state can be calculated P g2 ;

[0107] Then, the energy W of the high pressure gas doing work g It can be expressed as:

[0108] W g =(P g2 V g2 -P g1 V g1 ) / (1-γ g );

[0109] According to the above two equations, we can know that the energy W of high pressure gas doing work g for:

[0110]

[0111] In this embodiment, the initial pressure of the high-pressure gas P g1 is 81MPa, and the initial volume of high pressure gas is V g1 For 4 liters, the high pressure gas insulation coefficient γ g Take 1.4, the inner diameter D of the pump tube 02 is S7mm, and the length L of the pump tube 02 is 12m, then the volume of high-pressure gas V in the terminal state g2 Approximately:

[0112] V g2 =4+3.14×(57×10 -3 ) 2 ×12×10 3 / 4 = 34.605 liters;

[0113] The pressure of high pressure gas at the terminal state P g2 for:

[0114] P g2 =81×(4 / 34.605) 1.4 =3.949796MPa;

[0115] The energy W of high pressure gas doing work g for:

[0116] W g =(3.949796×34.605-81×4)×10 3 / (1-1.4)=468.293kJ;

[0117] (2) Energy consumption of light gas doing work W h

[0118] The initial pressure of light gas is P h1 , the initial volume of light gas V h1 V is the volume of the light gas in the inner cavity of the pump tube 02 and the high-pressure cone section 03 when the light gas injection is just completed in step 1, which is approximately V h1 =πD 2 L / 4; the light gas adiabatic coefficient is γ h ; Light gas volume V at terminal state h2 , approximate Where D h Indicates the inner diameter of the launch tube 04, L f represents the length of the launch tube 04; assuming that the pressure of the light gas in the terminal state is P h2 , then, according to the adiabatic process gas state equation:

[0119]

[0120] According to the above formula, the pressure P of the light gas in the terminal state can be calculated h2 , then the energy consumption of light gas doing work is W h It can be expressed as:

[0121] W h =(P h2 V h2 -P h1 V h1 ) / (1-γ h );

[0122] According to the above two equations, we can know that the energy consumption of light gas doing work is W h for:

[0123]

[0124] In this embodiment, the initial pressure of the light gas P h1 is 0.3MPa, the inner diameter D of the pump tube 02 is 57mm, the length L of the pump tube 02 is 12m, and the light gas insulation coefficient γ h Take 1.4, the inner diameter D of the launch tube 04 h is 12.7 mm, the length L of the launch tube 04 f is 3m, then the initial volume of the light gas is V h1 Approximately:

[0125] V h1 =3.14×(57×10 -3 ) 2 ×12 / 4=30.605 liters;

[0126] Light gas volume V at terminal state h2 Approximately:

[0127] V h2 =3.14×(12.7×10 -3 ) 2 × 3 / 4 = 0.3798 liters;

[0128] The pressure of light gas at the terminal state P h2 for:

[0129] P h2 =0.3×(30.605 / 0.3798) 1.4 =139.911576MPa;

[0130] Energy consumption of light gas doing work W h for:

[0131] W h=(139.911576×0.3798-0.3×30.605)×10 3 / (1-1.4)=-109.892kJ;

[0132] (3) Energy consumption W of the frictional force between the piston 06 and the pump tube 02 and between the projectile 08 and the launch tube 04 f

[0133] (3.1) Energy consumption W of the frictional force between piston 06 and pump tube 02 f1

[0134] Energy consumption W of the friction between piston 06 and pump tube 02 f1 It can be expressed as:

[0135] W f1 =F f1 L=μ f1 σ y1 (πDL f1 )L;

[0136] Where: F f1 Indicates the friction between the piston 06 and the pump tube 02; μ f1 Indicates the friction coefficient between the piston 06 and the pump tube 02, which is given according to the commissioning test data; σ y1 Indicates the yield strength of piston 06; L f1 Indicates the length of piston 06;

[0137] In this embodiment, μ f1 Take 0.04, σ y1 Take 20MPa, the inner diameter D of the pump tube 02 is 57mm, the length L of the pump tube 02 is 12m, and the length L of the piston 06 is f1 is 20 cm, then the energy consumption of the friction between piston 06 and pump tube 02 is W f1 for:

[0138] W f1 =0.04×20×3.14×57×200×12=343.642kJ;

[0139] (3.2) Energy consumption W of the frictional force between the projectile 08 and the launch tube 04 f2

[0140] Energy consumption W of the friction between the projectile 08 and the launch tube 04 f2 It can be expressed as:

[0141] W f2 =F f2 L f =μ f2 σy2 (πD h L f2 )L f ;

[0142] Where: F f2 is the friction between the projectile 08 and the launch tube 04; μ f2 represents the friction coefficient between the projectile 08 and the launch tube 04, which is given according to the commissioning test data; σ y2 Indicates the 08 yield strength of the projectile; L f2 Indicates the length of projectile 08;

[0143] In this embodiment, μ f2 Take 0.04, σ y2 20MPa, inner diameter D of launch tube 04 h is 12.7 mm, the length L of the launch tube 04 f is 3m, the length of projectile 08 is L f2 is 10 mm, then the energy consumption of the friction between the projectile 08 and the launch tube 04 is W f2 for:

[0144] W f2 =0.04×20×3.14×12.7×10×3=957J;

[0145] Then, the energy consumption of the overall frictional force is W f It can be expressed as:

[0146] W f =W f1 +W f2 ;

[0147] According to the above, the energy consumption W of the friction between the piston 06 and the pump tube 02 and between the projectile 08 and the launch tube 04 is f for:

[0148] W f =μ f1 σ y1 (πDL f1 )L+μ f2 σ y2 (πD h L f2 )L f ;

[0149] In this embodiment, the energy consumption W of the friction between the piston 06 and the pump tube 02 and between the projectile 08 and the launch tube 04 is f for:

[0150] W f=343.642+0.957=344.599kJ;

[0151] (4) Energy consumption W of piston 06 when it enters the cone p

[0152] Considering the quasi-static process, the wall of the high-pressure cone section 03 squeezes the piston 06, hindering the piston 06 from entering the cone. The resistance can be expressed by the virtual pressure P T On the other hand, the energy consumption of plastic deformation from extrusion of length ΔL0 to length ΔL1 is consistent with the extrusion process, ΔL1 is the displacement of the piston at the conical section, then:

[0153] P T S1ΔL1=σ y1 S p (ΔL0-ΔL1);

[0154] Where: S1 represents the original cross-sectional area of ​​the piston 06 when it is not deformed; S p Indicates the average cross-sectional area of ​​the front and rear ends of piston 06 in the terminal state, S p =(S1+S2) / 2, where S2 is the cross-sectional area of ​​the front end of the piston 06 in the terminal state; according to the law of conservation of volume, S2ΔL0=S1ΔL1; then, dividing both sides of the above equation by S1ΔL1, we get:

[0155]

[0156] Where: D bottom Indicates the original diameter of the piston 06 when it is not deformed; D top Indicates the diameter of the front end of piston 06 in the terminal state, which is an empirical value and is taken as 0.2D bottom ~0.95D bottom ;

[0157] Then, the energy consumption of piston 06 in the cone is W p for:

[0158]

[0159] Where: L p Indicates the depth of the front end of piston 06 into the cone, which is an empirical value;

[0160] In this embodiment, σ y1 Take 20MPa, the original diameter D of piston 06 when it is not deformed bottom The diameter D of the front end of the piston 06 at the terminal state is 57.1 mm. top Take 20mm, the front end of piston 06 enters the cone depth L p Take 100mm, the energy consumption of piston 06 entering the cone is W pfor:

[0161] W p =0.5×20×1.1227×7.151×3.14×57.1×57.1×0.1 / 4=20.548kJ;

[0162] (5) Energy consumption of gas leakage W S

[0163] Energy consumption of gas leakage W S The energy loss is mainly caused by the processing seal error and the gas leakage between the projectile 08 and the launch tube 04. For a fixed two-stage light gas gun projectile loading system, the gas leakage mainly occurs in the launch tube 04 part. The light gas leaks through the gap between the projectile 08 and the launch tube 04. The leakage amount is mainly related to the projectile launch speed v d , the pressure of light gas at the terminal state P h2 It is a function related to the two. The energy consumption of gas leakage W S It can be expressed as:

[0164] W s =k s v d P h2 ;

[0165] According to the above We can find P h2 , therefore, the energy consumption of gas leakage is W S for:

[0166]

[0167] Where: k s It represents the leakage coefficient, which is an empirical value given according to the commissioning test data and has a value between 0 and 1×10 -6 When the projectile 08 and the launch tube 04 always maintain an interference fit, the leakage coefficient is 0, and when there is a large gap between the projectile 08 and the launch tube 04, the leakage coefficient is 1×10 -6 , in an ideal state, it can be directly taken as 0; v d Indicates the projectile launch speed;

[0168] In this embodiment, the leakage coefficient k s Take 0.266×10 -6 , initial pressure of light gas P h1 is 0.3MPa, the initial volume of light gas V h1 The volume of light gas at the terminal state is 30.605 liters. h2 is 0.3798 liters, and the light gas adiabatic coefficient γ hTake 1.4, then the energy consumption of gas leakage is W S for:

[0169]

[0170] (6) Projectile kinetic energy consumption E k

[0171] Projectile kinetic energy consumption E k Directly expressed as the calculation formula of projectile kinetic energy, projectile kinetic energy consumption E k for:

[0172]

[0173] Where: m d Indicates the mass of the projectile 08;

[0174] In this embodiment, the projectile 08 mass m d is 5g, and the kinetic energy consumption of the projectile is E k for:

[0175]

[0176] Based on the law of conservation of energy, the energy equation constructed is:

[0177] W g =W h +W f +W p +W s +E k ;

[0178] In this embodiment, based on the law of conservation of energy, the energy equation constructed is:

[0179]

[0180] Step 2.3: Based on the energy equation constructed in step 2.2, calculate the projectile launch speed.

[0181] In this embodiment, the above quadratic equation is solved to calculate the projectile launch speed v d 4414.5m / s;

[0182] Step 3: Start the data acquisition system and the loading system of the secondary light gas cannon projectile in the system for calculating the firing speed of the secondary light gas cannon projectile, which are built in step 1 and have completed the injection of light gas and high-pressure gas, in order to obtain the actual firing speed of the projectile; specifically:

[0183] Step 3.1: Start the data acquisition system in the system for calculating the firing speed of the two-stage light gas cannon projectile, which has been built in step 1 and has completed the injection of light gas and high-pressure gas, and use the high-speed camera 6 to shoot and record the information of the above-mentioned ruler 7 set on the ballistic line. After shooting, remove the ruler 7 from the ballistic line;

[0184] Step 3.2: Start the secondary light gas cannon projectile loading system in the system for calculating the firing speed of the secondary light gas cannon projectile, which is built in step 1 and has completed the injection of light gas and high-pressure gas, and fire the projectile 08 installed in the launch tube 04. During the firing of the projectile 08, trigger the high-speed camera 6 to shoot and record the flight trajectory of the projectile 08;

[0185] Step 3.3: According to the information of the scale 7 recorded by the high-speed camera 6 in step 3.1 and the flight trajectory of the projectile 08 recorded by the high-speed camera 6 in step 3.2, the actual projectile launch speed is converted; when converting the actual projectile launch speed, the following formula is used for conversion:

[0186]

[0187] Where: v s represents the actual launch speed of the projectile; l represents the actual spacing selected from the information of the ruler 7 recorded by the high-speed camera 6 in step 3.1; δx cam Indicates the spacing of image pixels under the selected actual spacing l; δx s , δt respectively represent the selected projectile flight distance interval and the time taken by the projectile to fly the distance interval on the flight trajectory of the projectile 08 photographed and recorded by the high-speed camera 6 in step 3.2;

[0188] In this embodiment, the above l is 70 mm, δx cam 0.32245mm, δx s is 129.9507 mm, δt is 0.0062 s, then the actual launch speed v of the projectile is calculated s is 4550m / s; in actual calculation, multiple sets of corresponding l and δx can also be selected cam ,δx s And δt, multiple conversions are performed to obtain the actual launch speed v of multiple projectiles s , and then take the average as the final actual projectile launch speed v s ;

[0189] Step 4: Subtract the projectile launch speed calculated in step 2 from the actual projectile launch speed obtained in step 3 to determine whether the absolute value of the difference between the two is less than or equal to a preset error threshold; if so, execute step 5; if not, execute step 6;

[0190] In this embodiment, the error threshold is set to 200, and the projectile launch speed calculated in step 2 is 4414.5m / s, and the actual projectile launch speed obtained in step 3 is 4550m / s. The absolute value of the difference between the two is 135.5, which is less than the set error threshold of 200. This means that when calculating the projectile launch speed in step 2, the given relevant parameter values ​​are relatively appropriate, and no correction is required. Then, step 5 is directly executed; otherwise, it means that when calculating the projectile launch speed in step 2, the given relevant parameter values ​​are not appropriate and need to be corrected. In this case, step 5 needs to be skipped and step 6 needs to be executed.

[0191] Step 5: Record the relevant parameter values ​​given in step 2, and then proceed to step 7;

[0192] In this embodiment, the friction coefficient μ between the piston 06 and the pump tube 02 is recorded. f1 is 0.04, and the friction coefficient μ between the projectile 08 and the launch tube 04 f2 is 0.04, the leakage coefficient k s 0.266×10 -6 , then skip step 6 and proceed to step 7;

[0193] Step 6: Correct the relevant parameter values ​​given in step 2, and record the corrected relevant parameter values;

[0194] Step 7: Subsequently, the given relevant parameter values ​​recorded are used in the same way as in step 2 to calculate the projectile launch speed and complete the calculation.

[0195] In summary, the system and method for calculating the firing speed of a secondary light gas cannon projectile of the present invention builds a secondary light gas cannon projectile loading system from an energy perspective, converts the process of firing a projectile by the secondary light gas cannon projectile loading system into an energy transfer process of energy conversion and consumption, analyzes the energy transfer process in the process of firing the projectile, and calculates the projectile firing speed based on the law of conservation of energy; it realizes the application of the law of conservation of energy in the calculation of the firing speed of a secondary light gas cannon projectile; it not only simplifies the calculation flow and process of the firing speed of a secondary light gas cannon projectile and improves the convenience of calculation, but also can more vividly describe the physical process of firing a projectile by a secondary light gas cannon, improves the diversity of the internal ballistic analysis of the secondary light gas cannon, and can be expanded to the calculation of the firing speed of secondary light gas cannon projectiles loaded in various ways.

Claims

1. A system for calculating the launch velocity of a two-stage light gas cannon projectile, characterized in that: Includes a two-stage light gas gun projectile loading system and data acquisition system; The two-stage light gas gun projectile loading system comprises a gas source chamber (01), a pump pipe (02), a high-pressure cone section (03) and a launch tube (04) which are coaxially sealed and connected in sequence from back to front; The gas source chamber (01) is used to store high-pressure gas for launching; a large diaphragm (05) is provided at one end of the gas source chamber (01) connected to the pump tube (02) to separate the gas source chamber (01) from the inner cavity of the pump tube (02) before launching; A piston (06) is arranged in the inner cavity of the pump tube (02); a small diaphragm (07) is arranged at one end where the high-pressure cone section (03) is connected to the launch tube (04) to separate the inner cavity of the high-pressure cone section (03) from that of the launch tube (04) before launch; the inner cavity of the pump tube (02) and the high-pressure cone section (03) between the piston (06) and the small diaphragm (07) is filled with light gas; The inner cavity of the launch tube (04) is used to install the projectile (08) to be launched, and the frontmost projectile outlet end is the muzzle; During firing, the high-pressure gas penetrates the large diaphragm (05), pushing the piston (06) forward to compress the light gas, and the compressed light gas penetrates the small diaphragm (07), pushing the projectile (08) to be fired forward to fire it; The data acquisition system comprises a ruler (7) and a high-speed camera (6); The scale (7) is arranged on the ballistic line of the two-stage light gas gun projectile loading system; The high-speed camera (6) is used to photograph and record information of the scale (7) arranged on the trajectory before the projectile (08) is launched, and to photograph and record the flight trajectory of the projectile (08) when the projectile (08) is launched, so as to convert the two to obtain the actual projectile launch speed.

2. The system for calculating the launch velocity of a two-stage light gas cannon projectile according to claim 1, characterized in that: The high-pressure gas refers to a gas with a pressure greater than or equal to 1 MPa; The light gas is hydrogen or helium.

3. The system for calculating the launch velocity of a two-stage light gas cannon projectile according to claim 1, characterized in that: The high-speed camera (6) refers to a camera capable of capturing images at a speed of more than one thousand frames per second.

4. The system for calculating the launch velocity of a two-stage light gas cannon projectile according to any one of claims 1 to 3, characterized in that: The data acquisition system also includes a target box (1), a laser transmitter (2), a laser receiver (3), a photoelectric converter (4), an oscilloscope (5) and a supplementary light source (8); The target box (1) is arranged at the front end side of the launch tube (04), and the front end of the launch tube (04) extends into the target box (1); two groups of observation windows arranged in the front-to-back direction are symmetrically arranged on the left and right side surfaces of the target box (1), wherein one group of observation windows close to the rear end side is defined as the rear end observation window (101), and the other group is defined as the front end observation window (102); The laser transmitter (2) and the laser receiver (3) are coaxially arranged, and are respectively located on the left and right sides of the exterior of the target box (1) corresponding to the position of the rear end observation window (101); The input end of the laser receiver (3) is used to receive the laser emitted by the laser transmitter (2); the output end of the laser receiver (3) is connected to the high-speed camera (6) through the photoelectric converter (4) and the oscilloscope (5) in sequence, and is used to send a signal to the oscilloscope (5) through the photoelectric converter (4) when the laser emitted by the laser transmitter (2) is blocked by the emitted projectile (08), and trigger the high-speed camera (6) through the oscilloscope (5) to shoot and record the flight trajectory of the projectile (08); The fill light source (8) and the high-speed camera (6) are respectively located on the left and right sides of the exterior of the target box (1) corresponding to the position of the front observation window (102); a shading paper (9) is provided on the front observation window (102) on the side where the fill light source (8) is located; and the fill light source (8) is used to provide fill light for the high-speed camera (6).

5. A method for calculating the launch velocity of a two-stage light gas cannon projectile, characterized in that: The following steps are involved: Step 1: construct a system for calculating the projectile launch velocity of a two-stage light gas cannon as described in any one of claims 1 to 4, and inject light gas of the design required pressure into the inner cavity of the pump tube (02) and the high-pressure cone section (03) between the piston (06) and the small diaphragm (07), and inject high-pressure gas of the design required pressure into the inner cavity of the gas source chamber (01); Step 2: In the system for calculating the projectile launch speed of the two-stage light gas cannon projectile, which is constructed in step 1 and has already been injected with light gas and high-pressure gas, the process of launching the projectile (08) by the two-stage light gas cannon projectile loading system is converted into an energy transfer process of energy conversion and consumption, the energy transfer process in the process of launching the projectile (08) is analyzed, and based on the law of conservation of energy and given relevant parameters, the projectile launch speed is calculated; the relevant parameters include the friction coefficient μ between the piston (06) and the pump tube (02) f1 , the friction coefficient μ between the projectile (08) and the launch tube (04) f2 And the leakage coefficient k s ; Step 3: sequentially start the data acquisition system and the secondary light gas cannon projectile loading system in the system for calculating the secondary light gas cannon projectile firing speed, which are built in step 1 and have completed the injection of light gas and high-pressure gas, to obtain the actual projectile firing speed; Step 4: Subtract the projectile launch speed calculated in step 2 from the actual projectile launch speed obtained in step 3, and determine whether the absolute value of the difference between the two is less than or equal to a preset error threshold; If yes, go to step 5; if no, go to step 6; Step 5: Record the relevant parameter values ​​given in step 2, and then proceed to step 7; Step 6: Correct the relevant parameter values ​​given in step 2, and record the corrected relevant parameter values; Step 7: Subsequently, the given relevant parameter values ​​recorded are used in the same way as in step 2 to calculate the projectile launch speed and complete the calculation.

6. The method for calculating the firing velocity of a two-stage light gas cannon projectile according to claim 5, characterized in that: The pressure of the light gas in the inner cavity of the pump tube (02) and the high-pressure cone section (03) when the light gas injection is just completed in step 1 is recorded as the light gas initial pressure P h1 When the high-pressure gas injection in step 1 is just completed, the pressure of the high-pressure gas in the inner cavity of the gas source chamber (01) is recorded as the initial pressure of the high-pressure gas P g1 ; The step 2 is specifically as follows: Step 2.1: In the system for calculating the firing speed of a two-stage light-gas cannon projectile, which is constructed in step 1 and into which light gas and high-pressure gas have been injected, the process of firing the projectile (08) by the two-stage light-gas cannon projectile loading system is converted into an energy transfer process of energy conversion and consumption, and the energy transfer process in the process of firing the projectile (08) is analyzed; Step 2.2: In the system for calculating the firing speed of the secondary light gas cannon projectile built in step 1 and having completed the injection of light gas and high pressure gas, the structural parameters of the secondary light gas cannon projectile loading system, the initial pressure P of the light gas h1 , the initial pressure P of the high pressure gas g1 As well as the analysis results of step 2.1, based on the laws of thermodynamics and the law of conservation of energy, the energy equation is constructed; Step 2.3: According to the energy equation constructed in step 2.2, the projectile launch speed is calculated.

7. The method for calculating the firing velocity of a two-stage light gas cannon projectile according to claim 6, characterized in that: The analysis result of analyzing the energy transfer process during the launch of the projectile (08) in step 2.1 is: The energy source for launching the projectile (08) is: the energy W of the high-pressure gas injected into the inner cavity of the gas source chamber (01) in step 1 to do work g ; The energy consumption in the process of launching the projectile (08) includes: the energy consumption of the light gas doing work W h , the energy consumption W of the frictional force between the piston (06) and the pump tube (02) and between the projectile (08) and the launch tube (04) f , the energy consumption W of the piston (06) when entering the cone p , Energy consumption of gas leakage W s And the projectile kinetic energy consumption E k ; The E k is a mathematical formula containing the desired quantity, the projectile launch velocity; The energy equation constructed in step 2.2 is: W g =W h +W f +W p +W s +E k .

8. The method for calculating the firing velocity of a two-stage light gas cannon projectile according to claim 7, characterized in that: In the energy equation constructed in step 2.2, the energy W of the high-pressure gas doing work is g for: Where: V g1 γ represents the volume of the high-pressure gas in the inner cavity of the gas source chamber (01) when the high-pressure gas injection is just completed in step 1, that is, the initial volume of the high-pressure gas, which is equal to the volume of the inner cavity of the gas source chamber (01); g Represents the high-pressure gas adiabatic coefficient; V g2 represents the volume of high-pressure gas in the terminal state, wherein the terminal state refers to the state where the piston (06) stops moving and the projectile (08) has flown out of the muzzle, and V g2 Approximately: V g2 =V g1 +πD 2 L / 4; Wherein: D represents the inner diameter of the pump tube (02); L represents the length of the pump tube (02); In the energy equation constructed in step 2.2, the energy consumption of the light gas doing work is W h for: Where: V h1 represents the volume of the light gas in the inner cavity of the pump tube (02) and the high-pressure cone section (03) when the light gas injection is just completed in step 1, that is, the initial volume of the light gas, which is approximately V h1 =πD 2 L / 4; γ h Represents the light gas adiabatic coefficient; V h2 represents the volume of light gas at the terminal state, which is approximately Where D h represents the inner diameter of the launch tube (04), L f represents the length of the launch tube (04); In the energy equation constructed in step 2.2, the energy consumption W of the frictional force between the piston (06) and the pump tube (02) and between the projectile (08) and the launch tube (04) is f for: W f =μ f1 s y1 (πDL f1 )L+μ f2 s y2 (πD h L f2 )L f ; Where: μ f1 represents the friction coefficient between the piston (06) and the pump tube (02); σ y1 Indicates the yield strength of the piston (06); L f1 represents the length of the piston (06); μ f2 represents the friction coefficient between the projectile (08) and the launch tube (04); σ y2 represents the yield strength of the projectile (08); L f2 represents the length of the projectile (08); In the energy equation constructed in step 2.2, the energy consumption of the piston (06) when entering the cone is W p for: Where: D bottom Indicates the original diameter of the piston (06) when it is not deformed; D top Indicates the diameter of the front end of the piston (06) in the terminal state. It is an empirical value and is taken as 0.2D bottom ~0.95D bottom ; S1 represents the original cross-sectional area of ​​the piston (06) when it is not deformed; L p Indicates the depth of the front end of the piston (06) into the cone, which is an empirical value; In the energy equation constructed in step 2.2, the energy consumption of the gas leakage is W S for: Where: k s Indicates the leakage coefficient, which is an empirical value; v d Indicates the projectile launch speed; In the energy equation constructed in step 2.2, the kinetic energy consumption of the projectile is E k for: Where: m d Indicates the mass of the projectile (08).

9. The method for calculating the firing speed of a two-stage light gas cannon projectile according to claim 8, characterized in that: The step 3 is specifically as follows: Step 3.1: Start the data acquisition system in the system for calculating the firing speed of the two-stage light gas cannon projectile, which is built in step 1 and has completed the injection of light gas and high-pressure gas, and use a high-speed camera (6) to shoot and record the information of the ruler (7) set on the ballistic line. After shooting, remove the ruler (7) from the ballistic line; Step 3.2: starting the secondary light gas cannon projectile loading system in the system for calculating the firing speed of secondary light gas cannon projectiles which has been built in step 1 and has completed the injection of light gas and high-pressure gas, firing the projectile (08) installed in the firing tube (04), and during the firing of the projectile (08), triggering the high-speed camera (6) to capture and record the flight trajectory of the projectile (08); Step 3.3: According to the information of the scale (7) recorded by the high-speed camera (6) in step 3.1 and the flight trajectory of the projectile (08) recorded by the high-speed camera (6) in step 3.2, the actual launch speed of the projectile is calculated.

10. The method for calculating the firing velocity of a two-stage light gas cannon projectile according to claim 9, characterized in that: In step 3.3, according to the information of the scale (7) recorded by the high-speed camera (6) in step 3.1 and the flight trajectory of the projectile (08) recorded by the high-speed camera (6) in step 3.2, the actual launch speed of the projectile is converted by the following formula: Where: v s represents the actual launch speed of the projectile; l represents the actual spacing selected from the information of the ruler (7) recorded by the high-speed camera (6) in step 3.1; δx cam represents the spacing of image pixels under the actual spacing l selected; δx s , δt represent respectively the selected projectile flight distance interval and the time taken by the projectile to fly the distance interval on the flight trajectory of the projectile (08) recorded by the high-speed camera (6) in step 3.2.

Images