Launching mechanism and inclined water entry impact test system

Abstract

The invention provides a launching mechanism and an inclined water entry impact test system. The launching mechanism comprises a launching device, a test structure body and a launching frame, the launching frame comprises an erecting frame, a baffle and a sliding frame, the baffle is arranged at one end of the erecting frame, an opening is formed in the other end of the erecting frame, the launching device is installed on the sliding frame, the sliding frame is arranged on the erecting frame in a sliding mode, and the test structure body is arranged on the sliding frame. The end, away from the launching port, of the launching device is connected with the baffle through a first energy absorber, one end of the sliding frame is connected with the erecting frame through a second energy absorber, and the other end of the sliding frame is connected with the erecting frame through a third energy absorber. The launching mechanism generates recoil resistance through the first energy absorber, the second energy absorber and the third energy absorber. Ejection power is provided for the test structural body through the multiple phase change pipes, high-speed water entry of the test structural body can be achieved, appropriate damping parameters are matched for different load test structural bodies, and recoil in the launching process is buffered and eliminated.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change emission, and in particular to a launching mechanism and an inclined water-entry impact test system. Background Art

[0002] The structural ultra-high-speed water-entry impact test is an important research topic and one of the difficulties in the fields of shipbuilding, aviation, military industry, etc. For example, when equipment such as sea surface equipment airdropping, unmanned underwater vehicle launching, seaplane landing, marine lifeboat dropping, and anti-submarine missile water-entry enters the water, it needs to withstand extremely large instantaneous impact loads, which may cause structural deformation or even failure.

[0003] The prior art uses a gravity acceleration test to simulate the water-entry impact. This gravity test device needs to have an extremely high initial height (for example, a water-entry speed of 10 m / s requires a height of 5.1 meters), resulting in difficulty in realizing in the laboratory environment and low safety. At the same time, the precise adjustment of the impact angle has a significant impact on the load distribution and structural response, and the existing devices are difficult to balance the speed and angle control. For the test bench for the test of the supersonic launch of a structure (such as a missile), the greater the launch power required for the launch, the greater the recoil force generated on the test bench. Generally, it will exceed three times the weight of the structure itself. For example, a 1-ton missile generates a recoil force of more than 3 tons during launch, even exceeding the weight of the test bench, resulting in a large volume of the test system, high test costs, and low safety. Summary of the Invention

[0004] The purpose of the present invention is to provide a launching mechanism and an inclined water-entry impact test system, which can realize short-distance supersonic inclined water-entry impact tests of different structural loads, with controllable recoil force during the test process, adjustable and controllable water-entry angle and water-entry speed, and can be reused.

[0005] The technical solution of the present invention is: a launching mechanism, including a launching device with a launching port, a test structure body arranged in the launching device, and a launching rack. The launching rack includes an erection rack, a baffle plate, and a sliding rack. One end of the erection rack is provided with the baffle plate, and the other end of the erection rack forms an opening. The launching device is installed on the sliding rack, and the sliding rack is slidably arranged on the erection rack. The launching port is arranged close to the opening. One end of the launching device away from the launching port is connected to the baffle plate through a first energy absorber. One end of the sliding rack away from the opening is connected to the erection rack through a second energy absorber. One end of the sliding rack close to the opening is connected to the erection rack through a third energy absorber. When the launching device emits the test structure body from the launching port, the launching mechanism sequentially forms an initial state, a launching start state, a launching middle state, and a launching after state. During this process, the launching mechanism generates recoil force resistance through the first energy absorber, the second energy absorber, and the third energy absorber respectively.

[0006] Preferably, in the pre-launch state, the test structure, the launch device, and the sliding frame are integrally placed statically on the erection frame. The force relationships among the first energy absorber, the second energy absorber, the third energy absorber, the test structure, the launch device, and the sliding frame satisfy the following relational expressions: (1) (2) (3) In the formula, is the mass of the test structure, unit kg; is the mass of the launch device, unit kg; is the mass of the sliding frame, unit kg; is the acceleration due to gravity, unit m / s²; is the initial 0 value of the first energy absorber, the second energy absorber, and the third energy absorber; is the leveling displacement value of the second energy absorber, unit m; is the value determined by the second energy absorber according to the total load Mg value, unit m; is the total mass of the test structure, the launch device, and the sliding frame, unit kg; , , are the stiffness coefficients of the first energy absorber, the second energy absorber, and the third energy absorber respectively, unit N / m; is the launch angle, that is, the angle between the axis of the launch device and the horizontal plane, unit °.

[0007] Preferably, in the launch process state, the launch device and the sliding frame are integrally placed statically on the erection frame. The force relationships among the first energy absorber, the second energy absorber, the third energy absorber, the test structure, the launch device, and the sliding frame satisfy the following relational expressions: (4) (5) In the formula, is the displacement value during the ejection process of the second energy absorber, unit m; are the displacement values during the ejection processes of the first energy absorber and the third energy absorber, unit m; is the total mass of the launch device and the sliding frame, unit kg; is the mass of the test structure, unit kg; is the acceleration due to gravity, unit m / s²; is the acceleration of the ejection device, unit m / s 2 ; is the damping coefficient of the first energy absorber, unit N·s / m; is the damping coefficient of the second energy absorber, unit N·s / m; is the damping coefficient of the third energy absorber, with the unit of N·s / m; F1(t) is the instantaneous external force received by the damping system, with the unit of N; F2(t) is the actual output buffer force processed by the energy absorber damping system, that is, the force transmitted to the erection frame and the ground, with the unit of N; 、 、 are the stiffness coefficients of the first energy absorber, the second energy absorber and the third energy absorber respectively, with the unit of N / m; is the moving speed of the sliding frame changing with time, with the unit of m / s; is the launch angle, with the unit of °.

[0008] Preferably, in the launch state, the recoil force of the launch device causes the sliding frame and the launch device to generate sliding vibration, and the first energy absorber, the second energy absorber and the third energy absorber generate energy loss. The energy loss is calculated according to the following formula: (6) In the formula, is the energy dissipated by the first energy absorber, the second energy absorber and the third energy absorber within one vibration period, with the unit of J; is the vibration frequency, with the unit of rad / s; u0 is the maximum vibration amplitude, with the unit of m; is the first derivative of the vibration amplitude, with the unit of m / s; is the damping coefficient of the first energy absorber, with the unit of N·s / m; is the damping coefficient of the second energy absorber, with the unit of N·s / m; is the damping coefficient of the third energy absorber, with the unit of N·s / m; is the total resistance of the first energy absorber, the second energy absorber and the third energy absorber, with the unit of N; T is the total working time of the first energy absorber, the second energy absorber and the third energy absorber, with the unit of s; u is the displacement of the sliding frame, with the unit of m.

[0009] Preferably, after the launch is completed, the launch device and the sliding frame are statically placed on the erection frame as a whole. The force relationship between the first energy absorber, the second energy absorber, the third energy absorber and the launch device and the sliding frame satisfies the following relational expressions: (7) (8) In the formula, is the static displacement value of the second energy absorber after ejection, with the unit of m; is the acceleration due to gravity, with the unit of m / s²; are the static displacement values of the first energy absorber and the third energy absorber after ejection, with the unit of m; m1 is the total mass of the launch device and the sliding frame, with the unit of kg; is the launch angle, with the unit of °; , , are the stiffness coefficients of the first energy absorber, the second energy absorber, and the third energy absorber, with the unit of N / m; is the leveling displacement value of the second energy absorber, with the unit of m.

[0010] Preferably, the launching device includes a cylinder body and a connecting seat connected to the inner wall of the cylinder body. The connecting seat divides the cylinder body into an initial volume chamber and a launching chamber with a launching port. A base is installed at the end of the initial volume chamber. On the surface of the connecting seat facing the launching chamber, a tray and a test structure body are connected by a locking bolt. An ejection device for injecting high-pressure gas into the test structure body is arranged in the initial volume chamber, and a braking and buffering mechanism for braking the tray is arranged at the launching port.

[0011] Preferably, a plurality of guide rails are arranged in the cylinder body, and the plurality of guide rails are evenly distributed along the circumference of the cylinder body. Guide rail grooves adapted to the guide rails are arranged on the tray.

[0012] Preferably, a pressure relief hole is formed in the side wall of the cylinder body, and the pressure relief hole is arranged close to the launching port.

[0013] Preferably, the ejection device includes at least one phase change tube. The number of the phase change tubes is determined according to the preset launching speed of the test structure body and then calculating the pressure P0 of the high-pressure carbon dioxide mixed gas in the cylinder body after pressure equalization. When there are multiple phase change tubes, carbon dioxide is released into the initial volume chamber in sequence at a certain time interval. The high-speed water entry of the test structure body can be realized.

[0014] The present invention also provides an inclined water entry impact test system, including a launching platform, the above-mentioned launching mechanism, and an erection rod for supporting the inclination of the launching mechanism. The open end of the erection frame is hinged to the launching platform through a hinge shaft. A water pool is arranged beside the launching platform, and the water pool is arranged close to the open end of the erection frame. The installation position of the erection rod on the launching platform is adjustable.

[0015] Compared with the related technology, the beneficial effects of the present invention are as follows: 1. The energy absorbers designed in the launching mechanism form a three-stage damping buffer structure, which matches appropriate damping parameters for test structure bodies with different loads, realizes the buffering and elimination of the recoil force during the launching process, and greatly reduces the influence of the recoil force on the launching rack during the launching process; it can realize short-distance supersonic high-overload inclined water entry impact tests for test structure bodies with different structural loads. The recoil force during the test process is controllable, and the water entry angle and water entry speed are adjustable and controllable, and it can be repeatedly reinstalled and reused; II. At least one phase change tube is arranged in an array in the ejection device of the launch mechanism. High-pressure gas generated by the phase change tube acts in a sealed chamber composed of a base, a tray, and a cylinder body, pushing the tray and the test structure to accelerate axially along the cylinder body. When achieving supersonic acceleration for test structures with different loads, only by changing the number of phase change tubes and designing a reasonable phase change time interval of the phase change tubes, the system can obtain a supersonic inclined water entry impact velocity within an effective stroke of 9m. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. is a schematic structural diagram of the inclined water entry impact test system provided by the invention;

[0017] Figure 2 FIG. is a schematic installation structure diagram of the launch rack;

[0018] Figure 3 FIG. is a schematic structural diagram of the launch rack;

[0019] Figure 4 FIG. is a configuration diagram of the launch rack recoil force system;

[0020] Figure 5 FIG. is a schematic exploded structural diagram of the launch device;

[0021] Figure 6 FIG. is a schematic internal sectional view of the launch device;

[0022] Figure 7 FIG. is a schematic structural diagram of the tray;

[0023] Figure 8 FIG. is a schematic structural diagram of the ejection device.

[0024] In the drawings: 1. Launch device; 100. Initial volume chamber; 101. Base; 102. Ejection device; 1021. Phase change tube; 103. Cylinder body; 104. Test structure; 105. Braking and buffering mechanism; 106. Guide rail; 107. Tray; 1071. Sealing strip; 1072. Guide rail groove; 1073. First mounting hole; 108. Locking bolt; 109. Pressure relief hole; 1010. Connecting seat; 110. Launch chamber; 111. Launch port; 2. Launch rack; 21. Baffle; 22. Lifting interface; 26. Sliding rack; 261. Slide block; 271. First energy absorber; 272. Second energy absorber; 273. Third energy absorber; 28. Erection rack; 281. Track; 29. Open end; 3. Water pool; 4. High-speed camera; 5. Launch platform; 51. Second mounting hole; 6. Erection rod; 7. Fixed plate; 8. Hinge shaft. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. For the convenience of description, words such as "upper", "lower", "left", and "right" in the following text only indicate the same directions as the upper, lower, left, and right directions of the accompanying drawings themselves, and do not limit the structure.

[0026] As Figure 1 shown, an inclined water-entry impact test system provided in this embodiment includes a launching device 1, a launching rack 2, a water tank 3, a high-speed camera 4, a launching platform 5, an erection rod 6, a fixing plate 7, and a hinge shaft 8.

[0027] As Figure 2 , Figure 3 shown, the launching rack 2 includes an erection rack 28, a baffle 21, a hoisting interface 22, and a sliding rack 26. One end of the erection rack 28 is provided with the baffle 21, and the other end of the erection rack 28 forms an opening 29. The launching device 1 is installed on the sliding rack 26. Two parallel tracks 281 are provided in the middle of the erection rack 28, and a slider 261 that slides on the tracks 281 is provided on the sliding rack 26.

[0028] A launching port 111 is provided on the launching device 1, and the launching port 111 is arranged close to the opening 29. One end of the launching device 1 away from the launching port 111 is connected to the baffle 21 through a first energy absorber 271, and the first energy absorber 271 directly absorbs the recoil force generated by the launching device 1. The baffle 21 provides structural support for the ejection process and bears the recoil force of the cylinder body 103. One end of the sliding rack 26 away from the opening 29 is connected to the erection rack 28 through a second energy absorber 272, and the second energy absorber 272 absorbs the recoil force generated during the launching process of the test structure body 104. To achieve the launching of a greater load and improve the recoil force absorption effect of the test system, one end of the sliding rack 26 close to the opening 29 is connected to the erection rack 28 through a third energy absorber 273. When the launching device 1 emits the test structure body 104 from the launching port 111, the launching mechanism successively forms an initial state, a launching start state, a launching middle state, and a launching after state. During this process, the launching mechanism generates recoil force resistance through the first energy absorber 271, the second energy absorber 272, and the third energy absorber 273 respectively.

[0029] The erection frame 28 is provided with a hoisting interface 22. One end of the erection rod 6 is hinged with a fixing plate 7, and the other end of the erection rod 6 is hinged with the erection frame 28. The launch platform 5 is provided with multiple groups of second mounting holes 51, and the fixing plate 7 is bolted to a certain group of the second mounting holes 51 so as to be able to adjust the inclination angle of the erection frame 28, realizing the adjustment of the launch angle of the erection frame 28 from 0 to 90°. The end of the erection frame 28 provided with an open end 29 is hinged with the launch platform 5 through a hinge shaft 8. A water pool 3 is arranged beside the launch platform 5, and the water pool 3 is arranged close to the open end 29 (i.e., the launch port 111) of the erection frame 28. A high-speed camera 4 is arranged beside the water pool 3. By hoisting the hoisting interface 22 and taking the hinge shaft 8 of the launch frame 2 as the turning point, the launch frame 2 is turned to a suitable launch angle, and then the fixing plate 7 on the erection rod 6 is installed at a suitable position on the launch platform 5.

[0030] The first energy absorber 271, the second energy absorber 272 and the third energy absorber 273 are designed as damping cylinders, and they are configured with the launch device 1 according to the damping system as shown. Figure 4 shown.

[0031] In the pre-launch state, the test structure body 104, the launch device 1 and the sliding frame 26 are statically placed on the erection frame 28 as a whole. The force relationships among the first energy absorber 271, the second energy absorber 272, the third energy absorber 273, the test structure body 104, the launch device 1 and the sliding frame 26 satisfy the following relational expressions: (1) (2) (3) In the formula, is the mass of the test structure body 104, with the unit of kg; is the mass of the launch device, with the unit of kg; is the mass of the sliding frame (26), with the unit of kg; is the gravitational acceleration, with the unit of m / s²; is the initial value of 0 of the first energy absorber 271, the second energy absorber 272 and the third energy absorber 273; is the leveling displacement value of the second energy absorber 272, with the unit of m; is the value determined by the second energy absorber 272 according to the total load Mg value, with the unit of m; is the total mass of the test structure body 104, the launch device 1 and the sliding frame 26, with the unit of kg; are the stiffness coefficients of the first energy absorber 271, the second energy absorber 272 and the third energy absorber 273 respectively, with the unit of N / m; is the launch angle (i.e., the water entry angle), which is the angle between the axis of the barrel 103 of the launch device 1 and the horizontal plane, with the unit of °.

[0032] During the launch process, the launch device 1 and the sliding frame 26 are statically placed on the erection frame 28 as a whole. The force relationships among the first energy absorber 271, the second energy absorber 272, the third energy absorber 273, the test structure 104, the launch device 1, and the sliding frame 26 satisfy the following relational expressions: (4) (5) In the formula, is the displacement value during the ejection process of the second energy absorber 272, with the unit of m; are the displacement values during the ejection processes of the first energy absorber 271 and the third energy absorber 273, with the unit of m; is the total mass of the launch device and the sliding frame, with the unit of kg; is the mass of the test structure 104, with the unit of kg; is the acceleration due to gravity, with the unit of m / s²; is the acceleration of the ejection device, with the unit of m / s 2 ; is the damping coefficient of the first energy absorber 271, with the unit of N·s / m; is the damping coefficient of the second energy absorber 272, with the unit of N·s / m; is the damping coefficient of the third energy absorber 273, with the unit of N·s / m; F1(t) is the instantaneous external force received by the damping system, with the unit of N; F2(t) is the actual output buffer force after the energy absorber damping system processes, that is, the force transmitted to the launch frame erection frame and the ground, with the unit of N; 、 、 are the stiffness coefficients of the first energy absorber 271, the second energy absorber 272, and the third energy absorber 273 respectively, with the unit of N / m; is the moving speed of the sliding frame changing with time, with the unit of m / s; is the launch angle (i.e., the water entry angle), with the unit of °.

[0033] During the launch process, the recoil force of the launch device 1 causes the sliding frame 26 and the launch device 1 to generate sliding vibrations, and the first energy absorber 271, the second energy absorber 272, and the third energy absorber 273 generate energy losses. The energy losses are calculated according to the following formula: (6) In the formula, is the energy dissipated by the first energy absorber 271, the second energy absorber 272, and the third energy absorber 273 within one vibration cycle, with the unit of J; is the vibration frequency, unit: rad / s; u0 is the maximum vibration amplitude, unit: m; is the first-order derivative of the vibration amplitude, unit: m / s; is the damping coefficient of the first energy absorber 271, unit: N·s / m; is the damping coefficient of the second energy absorber 272, unit: N·s / m; is the damping coefficient of the third energy absorber 273, unit: N·s / m; is the total resistance of the first energy absorber 271, the second energy absorber 272 and the third energy absorber 273, unit: N; T is the total working time of the first energy absorber 271, the second energy absorber 272 and the third energy absorber 273, unit: s; u is the displacement of the sliding frame 26, unit: m.

[0034] When in the state after the launch ends, the launch device 1 and the sliding frame 26 are statically placed on the erection frame 28 as a whole, and the force relationship between the first energy absorber 271, the second energy absorber 272, the third energy absorber 273 and the launch device 1, the sliding frame 26 satisfies the following relational expressions: (7) (8) In the formula, is the static displacement value after the second energy absorber 272 ejects, unit: m; is the acceleration due to gravity, unit: m / s²; are the static displacement values after the first energy absorber 271 and the third energy absorber 273 eject, unit: m; m1 is the total mass of the launch device 1 and the sliding frame 26, unit: kg; is the launch angle, unit: °; , , are the stiffness coefficients of the first energy absorber 271, the second energy absorber 272 and the third energy absorber 273 respectively, unit: N / m; is the leveling displacement value of the second energy absorber 272, unit: m.

[0035] According to the recoil force resistance characteristics of the above launch rack 2, establish a recoil force resistance system model of the launch rack 2 through Amesim, establish the calculation models of formulas (1)-(8), and iteratively analyze appropriate design parameters.

[0036] Through calculation and analysis, for example: the mass of the test structure 104 , the mass of the launch device 1 , the mass of the sliding frame 26 kg, an initial pre - pressure of 5000 N is applied to the second energy - absorbing device 272 (to achieve force balance before ejection). A recoil force is applied to the launching device, with the peak recoil force set to 100000 N (simulating high - speed ejection and large recoil force impact), and the peak - force pulse width set to 0.05 s. By adjusting the damping coefficient c and stiffness coefficient k of the energy - absorbing device, the following damping cylinder strokes and the actual output buffer force F2(t) processed by the energy - absorbing device damping system under several recoil - force resistance system parameters are calculated, as shown in Table 1:

[0037] Under the conditions of a recoil force of 100000 N and a peak - force pulse width of 0.05 s, the actual output buffer force processed by the energy - absorbing device damping system is as low as 2346 N.

[0038] It can be seen that through reasonable design of the resistance system parameters, the action force of the recoil force of the supersonic high - overload water entry of the test structure 104 on the launch rack 2 and the foundation can be effectively reduced, thereby reducing the stiffness requirements for the launch rack 2 and the construction requirements for the foundation.

[0039] As Figure 5 、 Figure 6 shown, the launching device 1 includes a cylinder body 103 and a connecting seat 1010 connected to the inner wall of the cylinder body 103. The connecting seat 1010 divides the cylinder body 103 into an initial - volume chamber 100 and a launching chamber 110 with a launching port 111. A base 101 is installed at the end of the initial - volume chamber 100. On the surface of the connecting seat 1010 facing the launching chamber 110, a tray 107 and a test structure 104 are connected by a locking bolt 108. An ejection device 102 for injecting high - pressure gas into the test structure 104 is provided in the initial - volume chamber 100, and a braking and buffering mechanism 105 for braking the tray 107 is arranged at the launching port 111. The braking and buffering mechanism 105 adopts an energy - absorbing structure. During the test, after being impacted by the fast - moving tray 107, the energy - absorbing structure is compressed and deformed, converting the kinetic energy of the tray 107 into the deformation potential energy and deformation thermal energy during the deformation process of the energy - absorbing structure, so that the tray 107 decelerates and stops moving and quickly separates from the test structure 104.

[0040] A pressure - relief hole 109 is opened on the side wall of the cylinder body 103, and the pressure - relief hole 109 is arranged close to the launching port 111. When the tray 107 moves near the pressure - relief hole 109, the high - pressure gas in the cylinder body 103 quickly escapes from the pressure - relief hole 109, reducing the internal pressure and braking force of the cylinder body 103 when the tray 107 is braked.

[0041] As Figure 6 、 Figure 7As shown in the figure, a plurality of guide rails 106 are provided inside the cylinder body 103, and the plurality of guide rails 106 are evenly distributed along the circumference of the cylinder body 103. Guide rail grooves 1072 adapted to the guide rails 106 are provided on the tray 107. A plurality of first mounting holes 1073 for mounting the locking bolts 108 are provided on the tray 107, and a locking interface for mounting the locking bolts 108 is provided on the test structure body 104. And a sealing strip 1071 in contact with the inner wall of the cylinder body 103 is provided on the outer surface of the tray 107, and the plurality of sealing strips 1071 are evenly distributed in a circular shape.

[0042] The locking bolt 108 adopts a partial weakening design. For example, a weakening groove is provided thereon, and the fracture of the weakening groove (i.e., the unlocking force) needs to be greater than the gravity of the tray 107 and the test structure body 104. When the pressure in the initial chamber 100 reaches a specific value, the weakening groove fractures and unlocks. After unlocking, the tray 107 and the test structure body 104 start to accelerate.

[0043] Such as Figure 5 、 Figure 8 As shown in the figure, the ejection device 102 includes at least one phase change tube 1021, and the number of the phase change tubes 1021 is determined according to the preset launch speed of the test structure body 104 and then calculating the pressure P0 of the high-pressure carbon dioxide mixed gas in the cylinder body 103 after pressure equalization.

[0044] To realize the supersonic inclined water entry test of the test structure body 104 with different loads, the ejection device 102 is provided with a plurality of phase change tubes 1021. The plurality of phase change tubes 1021 emit carbon dioxide liquid-gas phase changes at different time intervals and release high-pressure carbon dioxide mixed gas to meet the out-of-cylinder speed of the test structure body 104.

[0045] According to the actual water entry speed requirement of the test structure body 104, calculate the pressure P0 of the high-pressure carbon dioxide mixed gas in the cylinder body 103 after pressure equalization, and thereby determine the number of the phase change tubes 1021 of the ejection device 102 and the release time interval of the plurality of phase change tubes 1021 。

[0046] It is known that the radius of the cylinder body 103 is ,the weight of the test structure body 104 is ,the radius of the pressure acting surface is ,the volume of the initial chamber 100 is ,the effective stroke of the test structure body 104 is ,the friction coefficient is ,the vertical acceleration angle is and is 90°.

[0047] The sum of the work energy of a single-phase change tube 1021, the initial energy of the air in the initial volume chamber 100, and the gravitational potential energy of the test structure 104 is equal to the sum of the energy of the working fluid in the initial volume chamber 100, the kinetic energy of the test structure 104, and the energy dissipated by the energy absorber: (9) In the formula, is the energy of the working fluid in the initial volume chamber 100, with the unit of J; is the moving speed of the test structure 104, with the unit of m / s; is the gravitational acceleration, with the unit of m / s²; h is the moving height of the test structure 104, with the unit of m; is the initial energy of the air in the initial volume chamber 100, with the unit of J; is the energy of the gas released from the phase change tube 1021 entering the initial volume chamber 100, with the unit of J.

[0048] (10) In the formula, is the mass of the air in the initial volume chamber 100, with the unit of kg; is the initial enthalpy value of the air in the initial volume chamber 100, is the molar volume of the air in the initial volume chamber 100, equal to 22.414 L / mol, is the molar mass of the air, equal to 28.97 g / mol.

[0049] The density of the air in the initial volume chamber 100 at time t : (11) In the formula, is the amount of air in the initial volume chamber 100, is the amount of substance entering the initial volume chamber 100 from the phase change tube 1021 at time t, is the travel distance of the test body at time t, with the unit of m.

[0050] The density of the working fluid entering the initial volume chamber 100 from the phase change tube 1021 at time t : (12) In the formula, is the mass of the liquid carbon dioxide entering the initial volume chamber 100 from the phase change tube 1021 at time t.

[0051] (13) (14) In the formula, is the mass flow rate of the released working fluid, with the unit of kg / s; is the release port area, with the unit ; is the pressure inside the phase change tube 1021, unit MPa; is the density of liquid carbon dioxide inside the phase change tube 1021, unit kg / m 3 ; is the adiabatic coefficient of the working fluid. For convenient calculation, the adiabatic coefficient of CO2, 1.289, is taken.

[0052] If the working fluid entering the initial volume chamber 100 from the phase change tube 1021 is CO2, then (15) In the formula, is the molar mass of CO2, equal to 44 g / mol.

[0053] Without considering air resistance, the acceleration of the test body : (16) In the formula, is the pressure inside the initial volume chamber 100 at time t, unit MPa; is the initial pressure of the air inside the initial volume chamber 100, i.e., the atmospheric pressure, unit MPa; is 90°.

[0054] The velocity of the test body : (17)

[0055] The travel of the test body : (18) The air and the working fluid gas inside the initial volume chamber 100 are at the same temperature and pressure. Given the density of the air inside the initial volume chamber 100 at time t , the density of the working fluid entering the initial volume chamber 100 from the phase change tube 1021 at time t , the energy released from the phase change tube 1021 into the initial volume chamber 100 , combined with the motion equation of the test body, the pressure inside the initial volume chamber 100 can be obtained.

[0056] When a single phase change tube 1021 does not meet the speed requirement of the test body, the number of phase change tubes 1021 can be increased to increase the speed of the test body.

[0057] i phase change tubes 1021 release carbon dioxide into the initial chamber 100 in sequence at a certain interval. The motion equation of the test body is different from that of a single phase change tube 1021 in that the carbon dioxide entering the initial chamber 100 from the phase change tube 1021 is not completed at one time, but the carbon dioxide energy released by n phase change tubes 1021 is accumulated at a certain time interval. The carbon dioxide energy in the initial chamber 100 : (19) In the formula, is the work energy of the first phase change tube 1021 entering the initial chamber 100 at time t0, is the work energy of the second phase change tube 1021 entering the primary chamber 100 at time t1, is the work done by the i-th phase change tube 1021 entering the primary chamber 100 at time ti.

[0058] The carbon dioxide energy released by a single phase change tube 1021 can be regarded as a Time series: (20) In the formula, is the time it takes for a single phase change tube 1021 to release energy, is the energy released at time t0, for The energy released at all times, is the time step of the energy sequence, for The energy released at each moment. Assume that there are i phase change tubes 1021 with The working fluid is released into the initial volume chamber 100 in sequence, and the time series of the total work amount is: (twenty one) The mass of carbon dioxide released by a single phase change tube 1021 is regarded as one Time series: (twenty two) In the formula, is the mass of carbon dioxide released by a single phase change tube 1021, is the time it takes for a single phase change tube 1021 to release energy, is the mass of carbon dioxide released at time t0, for The energy released at all times, is the time step of the CO2 mass series, for The mass of carbon dioxide released at the moment. Assuming that there are i phase change tubes 1021 with Release carbon dioxide into the initial volume chamber 100 in sequence according to the time sequence, and the time series of the total carbon dioxide mass is as follows: (23) In the formula, is the mass of carbon dioxide in the phase change tube 1021 entering the initial volume chamber 100 at time t0, is the mass of carbon dioxide in the phase change tube 1021 entering the initial volume chamber 100 at time t1, is the mass of carbon dioxide in the phase change tube 1021 entering the initial volume chamber 100 at time ti.

[0059] Substitute into formulas (11)-(18) to obtain the density of the air in the initial volume chamber 100 at time t , and the density of the carbon dioxide entering the initial volume chamber 100 from the phase change tube 1021 at time t . Combine with the motion equation of the test body to further obtain the pressure in the initial volume chamber 100 .

[0060] The process of determining the pressure in the initial volume chamber 100 for a single-phase change tube 1021 test is as follows: First, calculate the air quantity, mass, and energy in the initial volume chamber 100; then import the output mass and energy of a single-phase change tube 1021; combine with the air state in the initial volume chamber 100 to calculate the CO2 density and air density; first give a hypothetical pressure, substitute them into Refprop together to calculate the energy increments of CO2 and air; add the energy increments of CO2 and air to the kinetic energy of the test structure, and compare with the output energy of the phase change tube 1021; when the two are equal, the pressure at this time is the pressure in the initial volume chamber 100, combine with the motion equation of the test structure to obtain the motion acceleration, speed, and stroke of the test structure 104 at this time, and update the volume of the initial volume chamber; when the test structure 104 exits the cylinder, stop the calculation, and finally obtain the ballistic parameters in the initial volume chamber 100, including the pressure in the initial volume chamber, the motion acceleration of the test structure, the motion speed of the test structure, etc.

[0061] The simulation method includes the following process: S1. Use formula (16) to determine the output mass of the phase change tube 1021, determine the air quantity, mass, and initial energy in the initial volume chamber 100, and calculate the output energy of the phase change tube 1021; S2. According to the output mass of the phase change tube 1021 in step S1, as well as the air quantity, mass, and initial energy, use formula (14) to calculate the CO2 density and formula (13) to calculate the air density; S3. Assume an initial chamber pressure. In combination with step S2, use Refprop_Example_main.VI (the physical property parameters of CO2 and air refer to the Refprop database of the National Institute of Standards and Technology (NIST) of the United States. The Refprop software includes support for dynamic link libraries, allowing other applications to utilize the functions of Refprop) to calculate the energy increments of CO2 and air in the initial chamber 100; S4. Combine the energy increments of CO2 and air in the initial chamber, the kinetic energy of the test structure, and the gravitational potential energy of the test structure to obtain the output energy increment of the phase change tube 1021; S5. Compare the output energy of the phase change tube 1021 with the output energy increment of the phase change tube 1021 obtained in step S4. When they are equal, this pressure is the pressure in the initial chamber 100; S6. Accumulate the output mass and energy of the phase change tubes according to the ignition time sequence to obtain the output mass and energy of multiple phase change tubes 1021; S7. Substitute the output mass and energy of multiple phase change tubes 1021 into the motion equation of the test structure to obtain the motion acceleration, velocity, and displacement of the test structure at this time, and update the volume of the initial chamber 100. When the test structure 104 leaves the launch tube, stop the calculation.

[0062] Through calculation and analysis, for example: the mass of the test structure 104 , the mass of the tray 107 , the inner diameter dimension D of the cylinder 103 is 500 mm, the volume V0 of the initial chamber 100 is 20 L. By adjusting the number n, volume V1, and liquid injection amount m3 of the phase change tubes 1021 of the ejection device 102, as shown in Table 2:

[0063] Through reasonable internal ballistics design of carbon dioxide phase change ejection, supersonic water entry of the test structure 104 can be achieved.

[0064] The test process of the inclined water entry impact test system is as follows: S1. Through the lifting interface 22 of the lifting launch rack 2, adjust the launch rack 2 to the specified launch angle; S2. Fix the fixing plate 7 on the launch platform 5; S3. Start the high-speed camera 4 and the pressure sensor (set inside the cylinder 103); S4. Conduct sequential ignition on the ejection device 102. The high-pressure gas inside the phase change tube 1021 is instantly released into the cylinder 103, generating a thrust on the tray 107, pulling off the locking bolt 108, and pushing the test structure 104 to accelerate and move along the axial direction of the cylinder 103; In S5, after the test structure body 104 is accelerated to the target speed and exits the cylinder, after exiting the cylinder, the tray 107 stays in the cylinder body 103 under the action of the braking and buffering mechanism 105. When the tray 107 moves to the vicinity of the pressure relief hole 109, the internal gas pressure of the cylinder body 103 is instantaneously released, and the acceleration motion stops. In S6, the test structure body 104 inclines into the water; the high-speed camera 4 and the pressure sensor complete data acquisition; the test ends.

[0065] The described inclined water entry impact test system is convenient to operate, meets the requirements of economy, processability, practicability and operability, and the water entry speed can be adjusted greatly.

[0066] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied to other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. A launching mechanism, comprising a launching device (1) having a launching port (111) and a test structure body (104) disposed in the launching device (1), characterized in that, It further includes a launch rack (2), and the launch rack (2) includes an erection rack (28), a baffle (21) and a sliding rack (26). One end of the erection rack (28) is provided with the baffle (21), and the other end of the erection rack (28) forms an opening (29). The launch device (1) is installed on the sliding rack (26), and the sliding rack (26) is slidably arranged on the erection rack (28). The launch port (111) is arranged close to the opening (29). One end of the launch device (1) away from the launch port (111) is connected to the baffle (21) through a first energy absorber (271). One end of the sliding rack (26) away from the opening (29) is connected to the erection rack (28) through a second energy absorber (272). One end of the sliding rack (26) close to the opening (29) is connected to the erection rack (28) through a third energy absorber (273). When the test structure (104) is launched from the launch port (111) by the launch device (1), the launch mechanism sequentially forms a state before launch, a state during launch and a state after launch. During this process, the launch mechanism generates recoil resistance through the first energy absorber (271), the second energy absorber (272) and the third energy absorber (273) respectively.

2. The launching mechanism according to claim 1, wherein In the state before launch, the test structure (104), the launch device (1) and the sliding rack (26) are integrally static on the erection rack (28). The force relationships between the first energy absorber (271), the second energy absorber (272), the third energy absorber (273) and the test structure (104), the launch device (1), the sliding rack (26) satisfy the following relational expressions: （1） （2） （3） In the formula, is the mass of the test structure (104), in kg; is the mass of the launching device, in kg; is the mass of the sliding frame (26), in kg; is the acceleration due to gravity, in m / s²; is the initial value of 0 of the first energy absorber (271), the second energy absorber (272) and the third energy absorber (273); is the leveling displacement value of the second energy absorber (272), in m; is the value determined by the second energy absorber (272) according to the total load Mg value, in m; is the total mass of the test structure (104), the launching device (1) and the sliding frame (26), in kg; , , are the stiffness coefficients of the first energy absorber (271), the second energy absorber (272) and the third energy absorber (273) respectively, in N / m; is the launch angle, that is, the angle between the axis of the launching device (1) and the horizontal plane, in °.

3. The launching mechanism according to claim 1, characterized in that, In the state during launch, the launch device (1) and the sliding rack (26) are integrally static on the erection rack (28). The force relationships between the first energy absorber (271), the second energy absorber (272), the third energy absorber (273) and the test structure (104), the launch device (1), the sliding rack (26) are as follows: （4） （5） In the formula, is the displacement value during the ejection process of the second energy absorber (272), with the unit of m; is the displacement value during the ejection processes of the first energy absorber (271) and the third energy absorber (273), with the unit of m; is the total mass of the launching device (1) and the sliding frame (26), with the unit of kg; is the mass of the test structure body (104), with the unit of kg; is the acceleration due to gravity, with the unit of m / s²; is the acceleration of the ejection device, with the unit of m / s 2 ; is the damping coefficient of the first energy absorber (271), with the unit of N·s / m; is the damping coefficient of the second energy absorber (272), with the unit of N·s / m; is the damping coefficient of the third energy absorber (273), with the unit of N·s / m; F1(t) is the instantaneous external force received by the damping system, with the unit of N; F2(t) is the actual output buffer force processed by the energy absorber damping system, that is, the force transmitted to the erection frame (28) and the ground, with the unit of N; 、 、 are the stiffness coefficients of the first energy absorber (271), the second energy absorber (272) and the third energy absorber (273) respectively, with the unit of N / m; is the moving speed of the sliding frame (26) changing with time, with the unit of m / s; is the launch angle, with the unit of °.

4. The launching mechanism according to claim 1, characterized in that, In the state during launch, the recoil force of the launch device (1) causes the sliding rack (26) and the launch device (1) to generate sliding vibration, and energy losses occur in the first energy absorber (271), the second energy absorber (272) and the third energy absorber (273). The energy losses are calculated according to the following formula: （6） Wherein, is the energy dissipated by the first energy absorber (271), the second energy absorber (272) and the third energy absorber (273) within one vibration period, with the unit of J; is the vibration frequency, with the unit of rad / s; u0 is the maximum vibration amplitude, with the unit of m; is the first derivative of the vibration amplitude, with the unit of m / s; is the damping coefficient of the first energy absorber (271), with the unit of N·s / m; is the damping coefficient of the second energy absorber (272), with the unit of N·s / m; is the damping coefficient of the third energy absorber (273), with the unit of N·s / m; is the total resistance of the first energy absorber (271), the second energy absorber (272) and the third energy absorber (273), with the unit of N; T is the total working time of the first energy absorber (271), the second energy absorber (272) and the third energy absorber (273), with the unit of s; u is the displacement of the sliding frame (26), with the unit of m.

5. The launching mechanism according to claim 1, characterized in that, In the state after launch, the launch device (1) and the sliding rack (26) are integrally static on the erection rack (28). The force relationships between the first energy absorber (271), the second energy absorber (272), the third energy absorber (273) and the launch device (1), the sliding rack (26) satisfy the following relational expressions: （7） （8） In the formula, is the static displacement value of the second energy absorber (272) after ejection, with the unit of m; is the acceleration due to gravity, with the unit of m / s²; are the static displacement values of the first energy absorber (271) and the third energy absorber (273) after ejection, with the unit of m; m1 is the total mass of the launching device (1) and the sliding frame (26), with the unit of kg; is the launch angle, with the unit of °; , , are the stiffness coefficients of the first energy absorber (271), the second energy absorber (272) and the third energy absorber (273) respectively, with the unit of N / m; is the leveling displacement value of the second energy absorber (272), with the unit of m.

6. The launching mechanism according to claim 1, characterized in that, The launching device (1) includes a cylinder body (103) and a connecting seat (1010) connected to the inner wall of the cylinder body (103). The connecting seat (1010) divides the cylinder body (103) into a primary chamber (100) and a launching chamber (110) having a launching port (111). A base (101) is installed at the end of the primary chamber (100). On the surface of the connecting seat (1010) facing the launching chamber (110), a tray (107) and a test structure body (104) are connected by a locking bolt (108). An ejection device (102) for injecting high-pressure gas into the test structure body (104) is provided in the primary chamber (100). A braking and buffering mechanism (105) for braking the tray (107) is provided at the launching port (111).

7. The launching mechanism according to claim 6, characterized in that, A plurality of guide rails (106) are provided in the cylinder body (103), and the plurality of guide rails (106) are evenly distributed along the circumference of the cylinder body (103). The tray (107) is provided with guide rail grooves (1072) adapted to the guide rails (106).

8. The launching mechanism according to claim 6, characterized in that, A pressure relief hole (109) is formed in the side wall of the cylinder body (103), and the pressure relief hole (109) is provided close to the launching port (111).

9. The firing mechanism according to claim 6, characterized in that, The ejection device (102) includes at least one phase change tube (1021), and the number of the phase change tubes (1021) is determined according to the preset launching speed of the test structure body (104) and then calculating the pressure P0 of the high-pressure carbon dioxide mixture gas in the cylinder body (103) after pressure equalization; when there are a plurality of phase change tubes (1021), carbon dioxide is released into the primary chamber (100) in sequence at a certain time interval.

10. An inclined water-entry impact test system, comprising a launch platform (5), characterized in that, It further includes a launching mechanism according to any one of claims 1-9 and an erection rod (6) for supporting the inclination of the launching mechanism. The end of the erection frame (28) provided with an opening (29) is hinged to the launching platform (5) through a hinge shaft (8). A water pool (3) is arranged beside the launching platform (5), and the water pool (3) is arranged close to the opening (29) of the erection frame (28). The installation position of the erection rod (6) on the launching platform (5) is adjustable.

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