High-speed water entry impact test system and test method

Abstract

The present invention discloses a high-speed water entry impact test system and test method. The test system includes a carbon dioxide phase change acceleration module and a test structure assembly, and the test structure assembly includes a cylinder, a piston rod assembly, an electromagnetic suction cup, and a counterweight limit plate; a pressure sensor and a high-speed camera are installed in the test structure landing area in the test water tank, and a temperature sensor is installed in the carbon dioxide phase change acceleration module; in the initial state, the electromagnetic suction cup fixes the counterweight limit plate, the piston rod assembly, and the test structure in the initial position; when the test starts and the test structure has not entered the water, the counterweight limit plate, the piston rod assembly, and the test structure accelerate downward together until the test structure is accelerated to the target speed; when the test structure enters the water, the gas in the cylinder is depressurized and the acceleration of the test structure is stopped, and the test structure falls into the water body of the test water tank at the target speed. The present invention does not require a high water entry height to achieve high-speed structural entry into the water.

Description

Technical Field

[0001] The present invention relates to a structure water entry impact test, and in particular to a high-speed water entry impact test system and a test method. Background Art

[0002] When a structure enters the water, it inevitably experiences a violent impact with the water surface. Within a short period of time, the structure is subjected to enormous impact pressure, which can cause large plastic deformation or even damage to the local structure. This is especially true when the structure enters the water at an angle, and the water's reaction force does not pass through the structure's center of gravity. This creates a moment around the center of gravity, causing it to vibrate under the action of hydrodynamic forces, affecting the structure's stability and posing a serious threat to the reliability and safety of the entire structure. Therefore, there is an urgent need to conduct research on high-speed water entry impacts.

[0003] Chinese patent application CN116558761A discloses a high-speed water entry impact test device for structures based on spring acceleration. The device pre-accelerates the water entry test structure through a spring acceleration module, and then uses gravity to accelerate the structure to achieve high-speed water entry impact. However, this spring acceleration module is limited by the spring force and the effective action length of the spring. It is difficult to ensure that the water entry height meets the indoor height requirements of conventional laboratories while ensuring a high water entry speed. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a high-speed water impact test system and test method that can be performed in a laboratory.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A high-speed water entry impact test system includes a test bench and a test water tank. The test bench is erected above the test water tank, and a carbon dioxide phase change acceleration module and a test structure assembly are installed on the test bench, wherein:

[0007] The carbon dioxide phase change acceleration module is used to generate a high-pressure carbon dioxide mixed gas through carbon dioxide phase change. The carbon dioxide phase change acceleration module includes at least one phase change tube and a pressure equalizing chamber. Each phase change tube is connected to the pressure equalizing chamber in a time sequence.

[0008] The test structure components include:

[0009] A cylinder having a piston rod assembly mounted therein. The piston rod assembly includes a piston and a push rod. The piston divides the cylinder cavity into a first cavity and a second cavity along the cylinder axis. The first cavity is connected to the outlet of the equalizing chamber of the carbon dioxide phase change acceleration module. The push rod is mounted in the second cavity. One end of the push rod is connected to the piston, and the other end extends from the second cavity and is connected to the test structure.

[0010] Electromagnetic chuck, used to fix the initial position of the test structure;

[0011] A counterweight limiting plate is slidably mounted on the push rod and is attracted to the electromagnetic chuck, and a counterweight installation area for installing a counterweight is provided on the counterweight limiting plate;

[0012] A pressure sensor for monitoring water pressure changes in the test water tank and a high-speed camera for monitoring the water entry speed, water landing angle, and surface changes of the test structure during underwater movement are installed near the test structure landing area in the test water tank. A temperature sensor is installed in the carbon dioxide phase change acceleration module to monitor the temperature of the high-pressure carbon dioxide mixture.

[0013] In the initial state, the electromagnetic chuck fixes the counterweight limit plate, the piston rod assembly, and the test structure at the initial position;

[0014] After the test begins and the test structure is not submerged in water, under the action of the gas output by the carbon dioxide phase change acceleration module, the counterweight limit plate, the piston rod assembly, and the test structure accelerate downward together until the test structure accelerates to the target speed;

[0015] When the test structure enters the water, the gas in the cylinder is depressurized and the acceleration of the test structure is stopped. The test structure falls into the water of the test water tank at a target speed. At the same time, the pressure sensor monitors the water pressure when the test structure enters the water, and the high-speed camera monitors the entry speed, falling angle and surface changes of the test structure.

[0016] Preferably, the test structure assembly further comprises a guide rail mounted on the test bench, and the counterweight limiting plate is slidably mounted on the guide rail.

[0017] Preferably, a spring buffer is installed at the bottom of the guide rail, and the spring buffer is installed at the end of the stroke of the counterweight limiting plate.

[0018] Preferably, an angle adjustment unit is installed between the counterweight limit plate and the test structure, and the angle adjustment unit includes a plurality of angle adjustment bolts installed around the push rod, the heads of the angle adjustment bolts are placed on the upper surface of the counterweight limit plate and fastened with fixing nuts, and the screw portion of the angle adjustment bolts passes through the counterweight limit plate and is rotatably connected to the test structure.

[0019] Preferably, a pressure relief hole area is provided at the lower end of the second chamber of the cylinder, and a plurality of pressure relief holes are distributed in the pressure relief hole area. During the process of the test structure entering the water, the piston of the piston rod assembly moves to the pressure relief hole area.

[0020] Preferably, a phase change module fixing layer, an electromagnetic adsorption layer, a test buffer brake layer and a base are sequentially arranged on the test bench from top to bottom. The carbon dioxide phase change acceleration module is installed on the upper side of the phase change module fixing layer, and the cylinder is installed on the lower side. The electromagnetic suction cup is fixedly installed on the bottom of the electromagnetic adsorption layer, the counterweight limit plate is installed between the electromagnetic adsorption layer and the test buffer brake layer, and the base is placed in the test water tank.

[0021] Based on the same inventive concept, the present invention also provides a test method for the high-speed water impact test system, which comprises the following steps:

[0022] 1) According to the actual water entry speed requirement of the test structure, calculate the high-pressure carbon dioxide mixture pressure P(t) required in the cylinder, and use this to determine the number of phase change tubes in the carbon dioxide phase change acceleration module and the release time interval of multiple phase change tubes. ,in:

[0023] Cylinder pressure P(t), cylinder inner diameter D, cylinder effective stroke L, and water entry speed of the test structure The relationship between them is as follows:

[0024] ,

[0025] ,

[0026] In the formula The sum of the masses of the piston rod assembly, angle adjustment bolt, and counterweight limit plate, in kg; is the mass of the test structure, in kg; D is the inner diameter of the cylinder, in mm; P(t) is the pressure in the cylinder at time t, in MPa; L is the effective stroke of the cylinder, in m; g is the acceleration due to gravity, in m / s²;

[0027] 2) Install the test structure under the counterweight limit plate and set the water entry angle;

[0028] 3) Connect the initial position maintaining module of the water entry structure to the counterweight limit plate to fix the counterweight limit plate, the test structure and the piston rod assembly in the initial position;

[0029] 4) High-speed cameras, pressure sensors, and temperature sensors begin collecting data;

[0030] 5) Connect the carbon dioxide phase change acceleration module to an external power source and release a high-pressure carbon dioxide mixture. The high-pressure carbon dioxide mixture is instantly released into the cylinder and generates thrust on the piston rod assembly. Under the thrust of the piston rod assembly, the counterweight limit plate separates from the initial position holding module of the water entry structure, and the counterweight limit plate, piston rod assembly, and test structure accelerate downward together under the action of the high-pressure carbon dioxide mixture.

[0031] 6) After the test structure is accelerated to the target speed, it enters the water. During the process of the test structure entering the water, the cylinder is depressurized and the test structure stops accelerating.

[0032] 7) The high-speed camera, pressure sensor, and temperature sensor stop collecting data and the test ends.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1) This invention reduces the difficulty and testing cost of high-speed water entry. By using the liquid-to-gas phase transition of carbon dioxide to provide a high-pressure gas source, it achieves short-distance acceleration testing of the structure and high-speed water entry.

[0035] 2) The present invention can accurately determine the water entry speed of the test structure by using the number of phase change tubes and the release time interval of the carbon dioxide phase change acceleration module;

[0036] 3) The present invention can achieve rapid braking of the test structure through the reasonable arrangement of the pressure relief holes and the provision of the spring buffer;

[0037] 4) The high-speed water entry impact test system developed in the present invention can achieve high-speed water entry of structures without requiring a high water entry height, which is easy to implement and has low test investment costs. It can provide laboratory tests and verification of high-speed water entry impact of structures in the above-mentioned application scenarios, and has important engineering significance for the design of structural protection against water surface impact and ensuring the safety and reliability of structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 It is a schematic diagram of the overall structure of the test system of the present invention;

[0040] Figure 2 This is a schematic structural diagram of the carbon dioxide phase change acceleration module of the present invention;

[0041] Figure 3 It is a schematic diagram of the test structure components of the present invention;

[0042] Figure 4 It is a schematic diagram of the internal structure arrangement of the present invention;

[0043] Figure 5 This is a schematic diagram of the arrangement of the counterweight limiting plate of the present invention;

[0044] Figure 6 It is a schematic diagram of the test component layout of the present invention.

[0045] In the picture:

[0046] 1. Carbon dioxide phase change acceleration module, 11. Pressure equalization chamber, 12. Phase change tube;

[0047] 2. Diaphragm valve;

[0048] 31. Cylinder, 32. Piston rod assembly, 33. Electromagnetic chuck, 34. Counterweight limit plate, 35. Angle adjustment bolt, 36. Guide rail, 37. Spring buffer, 38. Test structure, 311. First chamber, 312. Second chamber, 313. Pressure relief hole, 321. Push rod, 322. Piston, 341. Guide hole, 342. Angle adjustment bolt through hole, 343. Piston rod assembly through hole, 344. Electromagnetic chuck active area, 345. Counterweight installation area, 351. Screw portion, 352. Fixing ring, 353. Fixing nut;

[0049] 4. Test bench, 41. Phase change module fixing layer, 42. Electromagnetic adsorption layer, 43. Test buffer brake layer, 44. Base;

[0050] 5. Test component, 51. High-speed camera, 52. Acquisition terminal, 53. Pressure sensor;

[0051] 6. Test water tank. DETAILED DESCRIPTION

[0052] The present invention will be further described below in conjunction with specific preferred embodiments, but the scope of protection of the present invention is not limited thereby.

[0053] In the description of the present invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0054] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0055] like Figure 1 As shown, an embodiment of the high-speed water entry impact test system of the present invention includes a carbon dioxide phase change acceleration module 1, a diaphragm valve 2, a test structure assembly 3, a test bench 4, a test assembly 5, and a test water tank 6. The carbon dioxide phase change acceleration module 1 is mounted on top of the test bench 4 and is used to generate a high-pressure carbon dioxide mixture through carbon dioxide phase change (generating a high-pressure carbon dioxide mixture through carbon dioxide phase change is a prior art technique, as detailed in Chinese patent application CN111457787A). The carbon dioxide phase change acceleration module 1 is connected to the test structure assembly 3 via the diaphragm valve 2. The test structure assembly 3 is mounted on the test bench 4. A test water tank 6 is located below the test structure assembly 3. The high-pressure carbon dioxide mixture released by the carbon dioxide phase change acceleration module 1 causes the test structure assembly 3 to move downward at high speed. The test water tank 6 houses the test assembly 5, which is used to detect the water entry velocity and impact pressure of the test structure assembly 3.

[0056] like Figure 2 As shown, the carbon dioxide phase change acceleration module 1 includes a pressure equalizing chamber 11 and at least one phase change tube 12 connected to the pressure equalizing chamber 11. The phase change tube 12 is used to change the liquid carbon dioxide into a liquid-gas phase to produce a high-pressure carbon dioxide mixture. Each phase change tube 12 releases the high-pressure carbon dioxide mixture into the pressure equalizing chamber 11 in a time sequence.

[0057] The diaphragm valve 2 remains closed during the test preparation process. At the start of the test, the high-pressure carbon dioxide mixture pressure released by the phase change tube 12 of the carbon dioxide phase change acceleration module 1 enters the equalizing chamber 11. The pressure of the high-pressure carbon dioxide mixture after equalization exceeds the pressure threshold of the diaphragm valve 2, causing the diaphragm valve 2 to automatically open. The high-pressure carbon dioxide mixture enters the cylinder 31 and pushes the piston rod assembly 32 downward.

[0058] like Figure 3 、 Figure 4As shown, the test structure assembly 3 includes a cylinder 31, a piston rod assembly 32, an electromagnetic suction cup 33, a counterweight limit plate 34, an angle adjustment bolt 35, a guide rail 36, a spring buffer 37 and a test structure 38. The cylinder 31 is mounted vertically downward on the test bench 4, and the piston rod assembly 32 is mounted inside the cylinder 31. The piston rod assembly 32 includes a piston 322 and a push rod 321. The piston 322 divides the cylinder cavity into a first chamber 311 and a second chamber 312 along the cylinder axis. The first chamber 311 is connected to the air outlet of the equalizing chamber 11 of the carbon dioxide phase change acceleration module 1. The push rod is installed. One end of the push rod 321 extends into the second chamber 312 and connects to the piston 322. The other end of the push rod 321 passes through the counterweight limit plate 34 and is rotatably connected to the middle part of the test structure 38. When the push rod 321 moves downward, the test structure 38 can move up and down along the axis of the cylinder 31 with the counterweight limit plate 34.

[0059] The guide rail 36 is vertically installed on the test bench 4, and the counterweight limit plate 34 is slidably installed on the guide rail 36. The spring buffer 37 is installed at the bottom of the guide rail 36. When the counterweight limit plate 34 moves downward into the water along the guide rail 36, the stroke finally falls on the spring buffer 37, and the buffering limit is achieved by the spring buffer 37.

[0060] A pressure relief hole 313 is provided in the lower end area of ​​the second chamber 312 of the cylinder 31. When the test structure 38 enters the water, when the piston 322 moves to the area of ​​the pressure relief hole 313, the gas in the first chamber 311 of the cylinder 31 is quickly released from the pressure relief hole 313, stopping the acceleration of the movement of the test structure 38, so that the test structure 38 is in a free state up and down after entering the water.

[0061] During the test, the piston 322 slides axially in a sealed manner in the cylinder 31, and the piston 322 plays a guiding role in causing the push rod 321 to move axially along the cylinder 31. The push rod 321 pushes the test structure 38 downward to accelerate to the horizontal plane and then stops rapid acceleration, so that the test structure 38 is in a free state up and down after entering the water.

[0062] The test assembly 5 includes a high-speed camera 51, an acquisition terminal 52, a pressure sensor 53 and a temperature sensor (not shown in the figure). The high-speed camera 51 is used to shoot the water entry speed of the test structure 38 and transmit it to the acquisition terminal 52. The temperature sensor is arranged in the carbon dioxide phase change acceleration module 1 to monitor the temperature of the high-pressure carbon dioxide mixture. The pressure sensor 53 is arranged in the test water tank 6 to collect water pressure data in the test water tank 6 and transmit it to the acquisition terminal 52. The acquisition terminal 52 is connected to the high-speed camera 51, the pressure sensor 53 and the temperature sensor. By receiving the water entry speed obtained by the high-speed camera 51, the pressure data collected by the pressure sensor 53, and the temperature data collected by the temperature sensor, and performing corresponding analysis and calculation (this part is the existing technology), relevant data of the test structure 38 at different times are obtained.

[0063] like Figure 5 As shown, to facilitate the installation of the counterweight limit plate 34, guide holes 341 are provided at the four corners of the counterweight limit plate 34. The counterweight limit plate 34 is slidably mounted on the guide rail 36 through the guide holes 341. In addition, the counterweight limit plate 34 is also provided with an angle adjustment bolt through-hole 342 for convenient passage of the angle adjustment bolt 35, a piston rod assembly through-hole 343 for convenient passage of the push rod 321, an electromagnetic suction cup action area 344, and a counterweight installation area 345. An electromagnetic suction cup 33 is installed above the electromagnetic suction cup action area 344. The electromagnetic suction cup 33 attracts the counterweight limit plate 34 and positions the counterweight limit plate 34 in its initial position. During the experiment, a counterweight can also be installed in the counterweight installation area 345 according to the test conditions, and the counterweight mass can be adjusted as needed.

[0064] The angle adjustment bolt 35 comprises a screw portion 351, a retaining ring 352, and a fixing nut 353. During installation, one end of the screw portion 351 passes through the angle adjustment bolt through-hole 342 and is pivotally connected to the top of the test structure 38 via a universal joint. The other end passes through the retaining ring 352 on the upper and lower surfaces of the counterweight stop plate 34 and is secured to the counterweight stop plate 34 via a fixing nut 353. In this manner, the provision of retaining rings 352 on both the upper and lower surfaces of the counterweight stop plate 34 limits the upward and downward sliding of the angle adjustment bolt 35 relative to the counterweight stop plate 34, ensuring that the submerged load of the test system is the test structure 38, the piston rod assembly 32, the angle adjustment bolt 35, and the counterweight stop plate 34.

[0065] The screw portion 351 has a clearance fit with the angle adjustment bolt through-hole 342 and the fixing ring 352, respectively, allowing the screw portion 351 to move up and down relative to the counterweight stop plate 34 through the angle adjustment bolt through-hole 342. The test structure 38 is connected and fixed to the counterweight stop plate 34 via a plurality of angle adjustment bolts 35. Each angle adjustment bolt 35 is evenly distributed around the push rod 321. The entry angle of the test structure 38 can be changed by adjusting the effective length of each angle adjustment bolt 35 (i.e., the distance between the corresponding point on the test structure 38 and the counterweight stop plate 34).

[0066] like Figure 6 As shown, to facilitate the installation of various components, the test bench 4 is provided with four layers, namely, from top to bottom, a phase change module fixed layer 41, an electromagnetic adsorption layer 42, a test buffer brake layer 43, and a base 44. The layers are connected as a whole by trusses. The base 44 is fixedly installed at the bottom of the test water tank 6. Four guide rails 36 are installed between the phase change module fixed layer 41 and the test buffer brake layer 43. The carbon dioxide phase change acceleration module 1 is installed on the phase change module fixed layer 41. The cylinder 31 is suspended between the phase change module fixed layer 41 and the electromagnetic adsorption layer 42. The electromagnetic suction cup 33 is fixedly installed below the electromagnetic adsorption layer 42. In the initial state, the electromagnetic force of the electromagnetic suction cup 33 adsorbs the counterweight limit plate 34 to the bottom of the electromagnetic adsorption layer 42. The counterweight limit plate 34 is slidably installed on the guide rail 36 between the electromagnetic adsorption layer 42 and the test buffer brake layer 43.

[0067] The test method of the high-speed water impact test system of the present invention comprises the following steps:

[0068] 1. According to the actual water entry speed requirement of the test structure 38, calculate the high-pressure carbon dioxide mixed gas pressure P(t) in the cylinder 31 after pressure equalization, and use this to determine the number of phase change tubes 12 of the carbon dioxide phase change acceleration module 1 and the release time interval of multiple phase change tubes 12 ;

[0069] 2. Install the test structure 38 below the counterweight limit plate 34 using the angle adjustment bolts 35 and set the water entry angle;

[0070] 3. Hoist the counterweight limit plate 34 until it engages with the electromagnetic chuck 33. During the hoisting process, the test structure 38 and the piston rod assembly 32 rise synchronously.

[0071] 4. Under the suction force of the electromagnetic chuck 33, the counterweight limit plate 34, the piston rod assembly 32, and the test structure 38 are fixed at the starting position;

[0072] 5. High-speed camera 51, pressure sensor 53, and temperature sensor begin collecting data;

[0073] 6. Connect the CO2 phase change acceleration module 1 to an external power source and release a high-pressure CO2 mixture. The high-pressure gas is instantly released into the first chamber 311 of the cylinder 31, generating thrust on the piston rod assembly 32. Under the thrust of the piston rod assembly 32, the counterweight limit plate 34 breaks free from the suction of the electromagnetic chuck 33. The counterweight limit plate 34, the piston rod assembly 32, and the test structure 38 accelerate downward together under the thrust of the piston rod assembly 32.

[0074] 7. After accelerating to the target speed, the test structure 38 enters the water and stops moving downward after being decelerated by the spring buffer 37 after entering the water to a certain depth. During the process of the test structure 38 entering the water, the piston 322 of the piston rod assembly 32 moves to the pressure relief area of ​​the cylinder 31, and the gas pressure in the cylinder is instantly released, and the accelerated movement stops.

[0075] 8. The high-speed camera 51, pressure sensor 53, and temperature sensor 54 stop collecting data, and the test ends.

[0076] In step 1 above, the calculation method of the high-pressure carbon dioxide mixed gas pressure P(t) in the cylinder 31 is:

[0077] Without considering the resistance, the pressure P(t) in the cylinder 31, the cylinder inner diameter D, the cylinder effective stroke L, and the water entry speed of the test structure are The relationship between them is as follows:

[0078] ,

[0079] ,

[0080] In the formula is the sum of the masses of the piston rod assembly 32, the angle adjustment bolt 35, and the counterweight limit plate 34, in kg; is the mass of the test structure 38, in kg; D is the inner diameter of the cylinder, in mm; P(t) is the pressure in the cylinder at time t, in MPa; L is the effective stroke of the cylinder, in m; g is the acceleration due to gravity, in m / s².

[0081] After calculation and analysis, for example: the mass of the test structure 38 The total mass of the piston rod assembly 32, the angle adjustment bolt 35, and the counterweight limit plate 34 The effective actuating stroke (water entry height) of cylinder 31 is L=3m, and the inner diameter of cylinder 31 is D=500mm. The technical parameters of the supercritical carbon dioxide phase change driven high-speed water entry impact test system are shown in the following table:

[0082] Technical parameters of supercritical carbon dioxide driven high-speed water impact test system

[0083]

[0084] Compared with the traditional free-fall water entry impact test method, when the test structure 38 is required to enter the water at a speed of 30m / s, the water entry height needs to reach 45m. When adopting the present invention, when the test structure 38 reaches a water entry speed of 30m / s, it is only necessary to provide the cylinder 31 with an effective actuating stroke (water entry height) L=3m. It can be seen that the high-speed water entry impact test system of the present invention can achieve high-speed entry of the accelerated structure into the water over a short distance compared to the traditional water entry impact test method, and the water entry speed can also be greatly adjusted. In addition, the high-speed water entry impact test system of the present invention is easy to operate and meets the requirements of economy, processability, practicality and operability.

[0085] In the above method, the number of phase change tubes 12 of the carbon dioxide phase change acceleration module 1 and the release time interval of multiple phase change tubes 12 are determined according to the high-pressure carbon dioxide mixed gas pressure P(t) in the cylinder 31 after pressure equalization. The method is:

[0086] It is known that the radius of cylinder 31 is The weight of the test body (the test body includes the test structure 38 and the piston rod assembly 32, the angle adjustment bolt 35, and the counterweight limit plate 34) is , the radius of the pressure action surface is , the volume of the pressure equalizing chamber 11 is , the effective stroke of the test body is , the friction coefficient is , the vertical acceleration angle is And it is 90°.

[0087] The sum of the work energy of a single phase change tube 12 and the initial energy of the air in the pressure equalization chamber 11 is equal to the sum of the energy of the liquid carbon dioxide in the phase change tube 12, the kinetic energy of the test body, and the gravitational potential energy of the test structure:

[0088] (1)

[0089] Where, is the working fluid energy in the equalizing chamber, J; is the speed of the test body, m / s; is the acceleration due to gravity, m / s²; h is the height of the test structure, m; is the initial energy of the pressure-equalized indoor air, J; The energy of a single phase change tube 12 releasing gas into the pressure equalization chamber, J.

[0090] (2)

[0091] Where, is the air mass in the equalizing chamber 11, kg; is the initial enthalpy of the air in the equalizing chamber 11, is the molar volume of air, equal to 22.414 L / mol, is the molar mass of air, which is equal to 28.97 g / mol.

[0092] Density of the air in the room at constant pressure :

[0093] (3)

[0094] Where, is the amount of air in the pressure chamber 11, is the amount of material entering the pressure equalizing chamber 11 from the phase change tube 12 at time t, is the distance of the test body at time t, m.

[0095] The density of the working fluid entering the pressure equalizing chamber 11 from the phase change tube 12 at time t :

[0096] (4)

[0097] Where, is the mass of liquid carbon dioxide entering the pressure equalizing chamber 11 from the phase change tube 12 at time t.

[0098] (5)

[0099] (6)

[0100] Where, is the mass flow rate of the released working fluid, kg / s; is the release port area, ; is the pressure inside the phase change tube 12, MPa; is the density of liquid carbon dioxide in the phase change tube 12, kg / m 3 ; is the adiabatic coefficient of the working fluid. For the convenience of calculation, Take the adiabatic coefficient of CO2 as 1.289.

[0101] The working medium entering the equalizing pressure chamber 11 from the phase change tube 12 is CO2, then

[0102] (7)

[0103] Where, is the molar mass of CO2, which is equal to 44 g / mol.

[0104] Without considering air resistance, the acceleration of the test body :

[0105] (8)

[0106] Where, is the pressure in the pressure equalizing chamber 11 at time t, MPa; is the initial pressure of the air in the equalizing chamber 11, i.e., atmospheric pressure, in MPa; is 90°.

[0107] Test subject movement speed :

[0108] (9)

[0109] Test body movement range :

[0110] (10)

[0111] The air and working gas in the equalizing chamber 11 are at the same temperature and pressure. The density of the air in the equalizing chamber 11 at time t is known. The density of the working fluid entering the pressure equalizing chamber 11 from the phase change tube 12 at time t , the phase change tube 12 releases the energy entering the pressure equalization chamber 11 , combined with the test body motion equation, the pressure in the equalizing chamber 11 can be calculated .

[0112] In the case that a single phase change tube 12 does not meet the test body speed requirement, the test body speed can be increased by increasing the number of phase change tubes 12 .

[0113] i phase change tubes 12 release carbon dioxide into the equalizing chamber 11 in sequence at a certain interval. The difference between the motion equation of the test body and that of a single phase change tube 12 is that the carbon dioxide entering the equalizing chamber 11 from the phase change tube 12 is not completed at one time, but the carbon dioxide energy released by n phase change tubes 12 is accumulated at a certain time interval. The carbon dioxide energy in the equalizing chamber 11 is :

[0114] (11)

[0115] Where, is the work energy of the first phase change tube 12 entering the pressure equalizing chamber 11 at time t0, is the work energy of the second phase change tube 12 entering the pressure equalizing chamber 11 at time t1, is the work done by the i-th phase change tube 12 entering the pressure equalizing chamber 11 at time ti.

[0116] The carbon dioxide energy released by a single phase change tube 12 can be regarded as a Time series:

[0117] (12)

[0118] Where, is the time it takes for a single phase change tube 12 to release energy, is the energy released at time t0, for The energy released at all times, is the time step of the carbon dioxide energy sequence (i.e., the time interval between releases from the phase change tube), for The energy released at each moment. Assume that there are i phase change tubes 12 with The working fluid is released into the equalizing chamber 11 in sequence, and the time series of the total work energy is:

[0119] (13)

[0120] The mass of carbon dioxide released by a single phase change tube 12 is regarded as a Time series:

[0121] (14)

[0122] Where, is the mass of carbon dioxide released by a single phase change tube 12, is the time it takes for a single phase change tube 12 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 carbon dioxide mass sequence (i.e., the time interval between releases from the phase change tube), for The mass of carbon dioxide released at the moment. Assume that there are i phase change tubes 12 with The carbon dioxide is released into the low-pressure chamber in sequence, and the time series of the total carbon dioxide mass is:

[0123] (15)

[0124] Where, is the mass of carbon dioxide entering the phase change tube 12 of the pressure equalizing chamber 11 at time t0, is the mass of carbon dioxide entering the phase change tube 12 of the pressure equalizing chamber 11 at time t1, is the mass of carbon dioxide entering the phase change tube 12 of the pressure equalizing chamber 11 at time ti.

[0125] Substituting into formula (3) to formula (10), the density of the air in the equalizing chamber 11 at time t can be obtained: , and the density of carbon dioxide entering the equalizing chamber 11 from the phase change tube 12 at time t , combined with the test body motion equation, the pressure in the equalizing chamber 11 is obtained .

[0126] In the process of determining the pressure of the equalizing chamber 11 using a single phase change tube 12 test, the air volume, mass, and energy in the equalizing chamber 11 are calculated, and then the mass and energy output by the single phase change tube 12 are imported. Combined with the air state in the equalizing chamber 11, the CO2 density and air density are calculated and substituted into Refprop_Example_main.VI together with the pressure (the physical properties 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). The energy increments of CO2 and air are calculated, added to the kinetic energy of the test body, and then compared with the energy increment output by the phase change tube 12. When the two are equal, the pressure at this time is the pressure in the equalizing chamber 11. Combined with the motion equation of the test body, the acceleration, velocity, and displacement of the test body at this time are obtained, and the volume of the equalizing chamber 11 is updated. When the test body completes its stroke, the calculation is terminated, and the pressure curve of the equalizing chamber 11 is finally obtained.

[0127] As shown above, the number of phase change tubes and the release time interval of the phase change tube 12 are constantly assumed during the calculation process. Perform calculations. For example, assuming the number is 5, the time sequence is 0-20ms-40ms-56ms-76ms, and the time step is 1ms. Through this step-by-step iterative calculation, the expected pressure value, velocity value, and displacement value are obtained. Then, based on the required test body entry speed requirement corresponding to the high-pressure carbon dioxide mixture pressure P(t) in the cylinder, the number of phase change tubes 12 of the carbon dioxide phase change acceleration module 1 required for the test and the release time interval of multiple phase change tubes 12 can be determined. .

[0128] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make many possible changes and modifications to the technical solution of the present invention using the technical content disclosed above, or modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent change, and modification made to the above embodiment in accordance with the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A high-speed water impact test system, comprising a test bench and a test water tank, wherein the test bench is mounted above the test water tank, and a carbon dioxide phase change acceleration module and a test structure assembly are mounted on the test bench, characterized in that: The carbon dioxide phase change acceleration module is used to generate a high-pressure carbon dioxide mixed gas through carbon dioxide phase change. The carbon dioxide phase change acceleration module includes at least one phase change tube and a pressure equalizing chamber. Each phase change tube is connected to the pressure equalizing chamber in a time sequence. The test structure components include: A cylinder having a piston rod assembly mounted therein. The piston rod assembly includes a piston and a push rod. The piston divides the cylinder cavity into a first cavity and a second cavity along the cylinder axis. The first cavity is connected to the outlet of the equalizing chamber of the carbon dioxide phase change acceleration module. The push rod is mounted in the second cavity. One end of the push rod is connected to the piston, and the other end extends from the second cavity and is connected to the test structure. Electromagnetic chuck, used to fix the initial position of the test structure; A counterweight limiting plate is slidably mounted on the push rod and is attracted to the electromagnetic chuck, and a counterweight installation area for installing a counterweight is provided on the counterweight limiting plate; A guide rail is mounted on the test bench, and the counterweight limit plate is slidably mounted on the guide rail; A pressure sensor for monitoring water pressure changes in the test water tank and a high-speed camera for monitoring the water entry speed, water landing angle, and surface changes of the test structure during underwater movement are installed near the test structure landing area in the test water tank. A temperature sensor is installed in the carbon dioxide phase change acceleration module to monitor the temperature of the high-pressure carbon dioxide mixture. In the initial state, the electromagnetic chuck fixes the counterweight limit plate, the piston rod assembly, and the test structure at the initial position; After the test begins and the test structure is not submerged in water, under the action of the gas output by the carbon dioxide phase change acceleration module, the counterweight limit plate, the piston rod assembly, and the test structure accelerate downward together until the test structure accelerates to the target speed; When the test structure enters the water, the gas in the cylinder is depressurized and acceleration of the test structure is stopped. The test structure falls into the water of the test water tank at a target speed. At the same time, the pressure sensor monitors the water pressure of the test structure when it enters the water, and the high-speed camera monitors the entry speed, angle of entry, and changes in the surface of the test structure. The method for determining the number of phase change tubes of the carbon dioxide phase change acceleration module and the release time interval of multiple phase change tubes is as follows: 1) Calculate the required high-pressure carbon dioxide mixture pressure in the cylinder based on the actual water entry speed of the test structure ,in: Cylinder pressure , Cylinder inner diameter size , Cylinder effective actuation stroke , the water entry speed of the test structure The relationship between them is as follows: In the formula is the sum of the masses of the piston rod assembly, angle adjustment bolt, and counterweight limit plate, in kg. is the mass of the test structure, in kg; is the cylinder inner diameter, unit ; is the pressure in the cylinder at time t, in units of ; is the effective stroke of the cylinder, in m; g is the acceleration due to gravity, in ; 2) Calculate the pressure in the pressure equalizing chamber when a single phase change tube is connected to the pressure equalizing chamber. : The radius of the cylinder is known to be The weight of the test body is , the radius of the pressure action surface is The volume of the equalizing chamber is , the effective stroke of the test body is , the friction coefficient is , the vertical acceleration angle is When , the sum of the work done by a single phase change tube and the initial energy of the air in the pressure-equalizing chamber is equal to the sum of the energy of the liquid carbon dioxide in the phase change tube, the kinetic energy of the test body, and the gravitational potential energy of the test structure: Where, is the working fluid energy in the equalizing chamber, J; is the speed of the test body, m / s; is the acceleration due to gravity, m / s²; h is the height of the test structure, m; is the initial energy of the pressure-equalized indoor air, J; The energy of a single phase change tube releasing gas into the pressure equalization chamber, J; Where, is the pressure-equalized indoor air quality, ; is the initial enthalpy of the equalized pressure indoor air, is the molar volume of air, is the molar mass of air; Test subject motion acceleration : Where, yes The pressure in the equalizing chamber is always maintained. ; is the initial pressure of the air in the equalized pressure room, that is, atmospheric pressure, ; is 90°; 3) Calculation When the phase change tubes are connected to the equalizing chamber in sequence at a certain interval, the pressure in the equalizing chamber : Equalized pressure indoor carbon dioxide energy : Where, yes The first phase change tube that enters the equalizing chamber at any moment does the work. yes The second phase change tube that enters the equalizing chamber at any moment does the work. yes Enter the equalizing chamber at the moment The work energy of the phase change tube; The carbon dioxide energy released by a single phase change tube is Time series: Where, is the time it takes for a single phase change tube to release energy, for The energy released at all times, for The energy released at all times, is the time step of the carbon dioxide energy sequence, that is, the time interval of the phase change tube release, for The energy released at every moment; Assume there is A phase change tube The working fluid is released into the equalizing chamber in sequence, and the time series of the total work energy is: The mass of carbon dioxide released by a single phase change tube is regarded as a Time series: Where, is the mass of carbon dioxide released by a single phase change tube (12), is the time it takes for a single phase change tube (12) to release energy, for The mass of carbon dioxide released at any moment, for The energy released at all times, is the time step of the carbon dioxide mass sequence (i.e., the time interval between releases from the phase change tube), for The mass of carbon dioxide released at any given moment; A phase change tube The carbon dioxide is released into the low-pressure chamber in sequence, and the time series of the total carbon dioxide mass is: ， Where, is the mass of carbon dioxide in the phase change tube entering the pressure equalization chamber at time t0, yes The mass of carbon dioxide in the phase change tube entering the equalizing pressure chamber at any moment, yes The mass of carbon dioxide in the phase change tube entering the equalizing pressure chamber at any moment; Obtain Density of the air in the room at constant pressure and The density of carbon dioxide entering the equalizing chamber from the phase change tube at any moment Then, combined with the test body motion equation, we can get When the phase change tube is connected to the pressure equalizing chamber, the pressure in the pressure equalizing chamber ; 4) When performing specific calculations, the number of phase change tubes and the time interval between releases of the phase change tubes are continuously assumed. Through step-by-step iterative calculations, an expected pressure value, velocity value, and displacement value are obtained. Then, the corresponding high-pressure carbon dioxide mixture pressure in the cylinder is calculated based on the required test body water entry speed. Requirements: Determine the number of phase change tubes of the carbon dioxide phase change acceleration module required for the test and the release time interval of multiple phase change tubes .

2. The high-speed water impact test system according to claim 1, characterized in that: The test structure assembly further includes a guide rail mounted on the test bench, and the counterweight limiting plate is slidably mounted on the guide rail.

3. The high-speed water impact test system according to claim 2, characterized in that: A spring buffer is installed at the bottom of the guide rail, and the spring buffer is installed at the end of the stroke of the counterweight limiting plate.

4. The high-speed water impact test system according to claim 1, characterized in that: An angle adjustment unit is installed between the counterweight limit plate and the test structure. The angle adjustment unit includes a plurality of angle adjustment bolts installed around the push rod. The heads of the angle adjustment bolts are placed on the upper surface of the counterweight limit plate and fastened with fixing nuts. The screw portion of the angle adjustment bolt passes through the counterweight limit plate and is rotatably connected to the test structure.

5. The high-speed water impact test system according to claim 1, characterized in that: A pressure relief hole area is provided at the lower end of the second chamber of the cylinder, and a plurality of pressure relief holes are distributed in the pressure relief hole area. During the entry of the test structure into water, the piston of the piston rod assembly moves to the pressure relief hole area.

6. The high-speed water impact test system according to claim 1, characterized in that: The test bench is provided with a phase change module fixed layer, an electromagnetic adsorption layer, a test buffer brake layer and a base from top to bottom. The carbon dioxide phase change acceleration module is installed on the upper side of the phase change module fixed layer, and the cylinder is installed on the lower side. The electromagnetic suction cup is fixedly installed on the bottom of the electromagnetic adsorption layer. The counterweight limit plate is installed between the electromagnetic adsorption layer and the test buffer brake layer. The base is placed in the test water tank.

7. A test method for a high-speed water impact test system according to any one of claims 1 to 6, characterized in that: The following steps are involved: 1) Calculate the required high-pressure carbon dioxide mixture pressure in the cylinder based on the actual water entry speed of the test structure , in order to determine the number of phase change tubes in the carbon dioxide phase change acceleration module and the release time interval of multiple phase change tubes ; 2) Install the test structure under the counterweight limit plate and set the water entry angle; 3) Connect the initial position maintaining module of the water entry structure to the counterweight limit plate to fix the counterweight limit plate, the test structure and the piston rod assembly in the initial position; 4) High-speed cameras, pressure sensors, and temperature sensors begin collecting data; 5) Connect the carbon dioxide phase change acceleration module to an external power source and release a high-pressure carbon dioxide mixture. The high-pressure carbon dioxide mixture is instantly released into the cylinder and generates thrust on the piston rod assembly. Under the thrust of the piston rod assembly, the counterweight limit plate separates from the initial position holding module of the water entry structure, and the counterweight limit plate, piston rod assembly, and test structure accelerate downward together under the action of the high-pressure carbon dioxide mixture. 6) After the test structure is accelerated to the target speed, it enters the water. During the process of the test structure entering the water, the cylinder is depressurized and the test structure stops accelerating. 7) The high-speed camera, pressure sensor, and temperature sensor stop collecting data and the test ends.

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