A Numerical Calculation Method for Underwater Explosion Shock and Cavitation Loads with Dual Explosion Sources

Abstract

The present invention provides a numerical calculation method for the underwater explosion shock cavitation load of a double explosion source, belonging to the technical field of explosion shock wave calculation based on computer data processing. This method uses the local discontinuous Galerkin (LDG) method to solve the propagation process of the far-field underwater double explosion source explosion shock wave in a two-dimensional acoustic flow field, and then studies the cavitation characteristics of the flow field under the action of the underwater double explosion source explosion shock wave. The dynamic pressure results of the flow field calculated by this method are compared with the calculation results of the acoustic finite element method. The results show that the dynamic pressure results of the flow field calculated by this method are in good agreement with the calculation results of the acoustic finite element method, verifying the effectiveness and accuracy of this method.

Description

Technical Field

[0001] The present invention belongs to the technical field of explosion shock wave calculation based on computer data processing, and particularly relates to a numerical calculation method for double-explosion-source underwater explosion shock cavitation load. Background Technique

[0002] Existing research on underwater explosion shock waves, especially numerical simulation research, mostly focuses on single-explosion-source scenarios. However, in actual engineering applications, multi-explosion-source underwater explosions are also very common, such as the series detonation of naval mines and the coordinated attack of multiple ammunitions. The shock waves generated by multi-explosion-source explosions will have a coupling superposition effect, and the propagation characteristics and cavitation effects of the load are significantly different from those of single-explosion-source explosions. The existing technology has not studied the propagation law and cavitation characteristics of multi-explosion-source underwater explosion shock waves deeply and systematically enough. In terms of the interaction between double-explosion sources, the shock wave coupling effect, and the resulting complex cavitation phenomenon, the existing technology is difficult to provide accurate and reliable numerical simulation results. Summary of the Invention

[0003] Aiming at the above problems, the present invention aims to overcome the lack of in-depth research on the propagation and cavitation characteristics of double-explosion-source underwater explosion shock waves in the existing technology, and the lack of in-depth understanding and accurate simulation methods. Especially in terms of the interaction between double-explosion sources, the shock wave coupling effect, and the resulting complex cavitation phenomenon, the existing technology is difficult to provide accurate and reliable numerical simulation results. The present invention aims to solve how to provide a numerical calculation method that can accurately simulate the propagation and cavitation characteristics of double-explosion-source underwater explosion shock waves, filling the gap in the research of double-explosion-source scenarios in the existing technology.

[0004] The present invention provides a numerical calculation method for double-explosion-source underwater explosion shock cavitation load, including the following processes:

[0005] Step 1, based on the working conditions of double-explosion-source underwater explosion shock cavitation load, establish a flow field model by setting the flow field range and its size parameters, and discretize the flow field model into grid cells to obtain relevant information of the discrete element flow field;

[0006] Step 2, calculate the distance between the explosive source point and the explosion point based on the relevant information of the discrete element flow field, the position of the explosive placement, and the position of the flow field explosion point;

[0007] Step 3, set the position of the flow field incident wave loading surface, and calculate the distance between any point on the flow field incident wave loading surface and the explosive source point;

[0008] Step 4, based on the relevant information of the discrete element flow field, the distance between the explosive source point and the explosion point, and the distance between any point on the flow field incident wave loading surface and the explosive source point, calculate the gradient of the dynamic pressure at any point x j on the flow field incident wave loading surface in the space direction ;

[0009] Step 5: Based on the results of Steps 1 to 4, characterize the boundary conditions at the double-explosion-source incident wave loading surface of the computational domain, and construct a numerical model for the propagation of the underwater explosion shock wave of the double-explosion source in the acoustic flow field;

[0010] Step 6: Based on the discrete element flow field phase information in Step 1 and the control equation for the propagation of the underwater explosion shock wave of the double-explosion source in the discrete element acoustic flow field, calculate the numerical flux at the boundary of the discrete element flow field to obtain the dynamic pressure results of the discrete element flow field;

[0011] Step 7: Introduce a pressure truncation model to handle the cavitation effect, identify the region where the absolute pressure of the flow field is lower than the cavitation limit, and obtain the position results of the cavitation region in the flow field;

[0012] Step 8: After calculating the physical quantities of all elements in the discrete element flow field at the initial moment based on the above process, calculate the physical quantities of all elements in the discrete element flow field at the next moment. By continuously looping this step in the time domain, finally obtain the dynamic pressure and total pressure calculation results of all discrete elements in the flow field at all calculation time steps.

[0013] Preferably, the relevant information of the discrete element flow field in Step 1 is obtained by a program to read the node numbers, coordinate positions, and node information of each element in the flow field model.

[0014] Preferably, the specific calculation method of Step 2 is as follows:

[0015] ;

[0016] In the formula, represents the vector position coordinates of the th explosive source point, represents the vector position coordinates of the th explosive detonation point, R 0i represents the distance between the i th explosive source point and detonation point.

[0017] Preferably, the specific calculation method of Step 3 is as follows:

[0018] ;

[0019] In the formula, x ji represents the vector position coordinates of the point of the i th explosive on the incident wave loading surface, represents the vector position coordinates of the th explosive source point, R ji represents the iThe distance between any point on the incident wave loading surface corresponding to an explosive and the explosive source point.

[0020] Preferably, step 4 is specifically as follows:

[0021] The calculation formula for any point x on the incident wave loading surface of the underwater explosion incident wave in the discrete element flow field is: j as follows:

[0022] ;

[0023] In the formula, is the delay time, , c is the propagation speed of the shock wave in the flow field, , is the fluid bulk modulus, is the fluid density; is the load amplitude value of the explosive at the detonation point; represents the spatial variation of the pressure field load at any point x on the incident wave loading surface j ;

[0024] The incident wave loading surfaces of the two explosives are the same plane. Using the wave superposition principle, the pressure gradients of the two explosives on the incident wave loading surface are coupled and superimposed to calculate the spatial gradient j of the dynamic pressure at any point x on the incident wave loading surface of the discrete element flow field .

[0025] Preferably, the control equation for the propagation of the double-explosion-source underwater explosion shock wave in the discrete element acoustic flow field in step 5 is:

[0026] ;

[0027] In the formula, is the element e in the discrete element flow field, is the boundary of the element e in the discrete element flow field;

[0028] ;

[0029] ;

[0030] ;

[0031] Among them represents the basis function describing the spatial physical quantity in the element, N is the total number of basis functions in an element; j is the index of the basis function, used to identify the j th basis function in the basis function matrix; denotes the value of the corresponding physical quantity at the j th basis function of the element; p is the dynamic pressure in the flow field; x and y represent the directions of the two-dimensional Cartesian coordinate system of the flow field; denotes the partial derivative of the fluid dynamic pressure with respect to time; denotes the second-order partial derivative of the fluid dynamic pressure with respect to time; denotes the partial derivative of the fluid dynamic pressure with respect to x direction; denotes the partial derivative of the fluid dynamic pressure with respect to y direction; and are the numerical fluxes of each term in F and G on the element boundary; , where , and are test functions; denotes the test function with respect to x direction; denotes the test function with respect to y direction.

[0032] Preferably, in step 6, the numerical fluxes at the boundaries of the discrete element flow field are calculated, and the expressions for solving the numerical fluxes under different boundary conditions are as follows:

[0033] ;

[0034] ;

[0035] ;

[0036] In the formula, + represents the physical quantity located on the element K , and – represents the physical quantity of another element adjacent to the side K of the element e ; is the unit outer normal vector of the element boundary, denotes the dynamic pressure at the side K of the element e , denotes the time derivative of the fluid dynamic pressure at the non-reflecting boundary element; , where is the length of the side e .

[0037] Preferably, in step 7, the position where the cavitation region appears in the flow field is calculated specifically as follows:

[0038] ;

[0039] ;

[0040] ;

[0041] In the formula, p is the dynamic pressure in the flow field, is the pseudo-dynamic pressure, is the displacement of the fluid particle, is the absolute pressure at the flow field calculation point, is the atmospheric pressure, is the fluid density, is the acceleration of gravity, is the water depth at the calculation point, is the cavitation limit, and the cavitation limit is set to 0, indicating that the fluid cannot transmit negative pressure.

[0042] Preferably, step 8 is to calculate the physical quantities of all units in the discrete element flow field at the next moment by using the fourth-order Runge-Kutta method. By continuously looping this step in the time domain, the calculation results of the dynamic pressure and total pressure of all discrete elements in the flow field at all calculation time steps are finally obtained, realizing the evolution simulation of the propagation characteristics and cavitation characteristics of the underwater explosion shock wave of the double explosion sources in the acoustic flow field.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The core inventive point of the present invention lies in proposing a numerical calculation method for the underwater explosion shock cavitation load of double explosion sources based on the local discontinuous Galerkin (LDG) method and applying it to the underwater double explosion source explosion scenario, effectively solving the deficiencies existing in the prior art in related fields.

[0045] 1. The present invention innovatively introduces the LDG method into the numerical simulation study of the underwater explosion shock wave of double explosion sources. By coupling the pressure gradient at the incident wave loading surface of the double explosion sources, the accurate characterization of the superposition effect of the underwater explosion shock load of the double explosion sources is realized. This method effectively simulates the spatial distribution characteristics, dynamic interaction mechanism and non-linear attenuation law of the underwater explosion shock load of the double explosion sources, and for the first time reveals the influence mechanism of the double explosion source shock wave on the cavitation characteristics of the flow field, overcoming the key technical bottlenecks such as large numerical dissipation and insufficient accuracy existing in the shock wave propagation simulation by the traditional finite element method.

[0046] 2. For the underwater double explosion source explosion scenario, the present invention can systematically analyze the influence laws of key parameters such as the explosion distance, mass ratio and detonation time between the two explosives on the cavitation characteristics of the flow field, reveal the interaction process between shock waves and the evolution process of cavitation phenomenon under different parameter combinations, and provide important theoretical guidance and design basis for the engineering application of underwater explosion. Brief Description of the Drawings

[0047] In order to more clearly illustrate the technical solutions of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following description is only one embodiment of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0048] Figure 1 It is a flowchart of the overall calculation process of the present invention.

[0049] Figure 2 It is a schematic diagram of the calculation model of the double-explosion-source underwater explosion shock cavitation load of the present invention.

[0050] Figure 3 It is a comparison chart of the results of the LDG method and the acoustic finite element method.

[0051] Figure 4 It is a schematic diagram of the propagation of the double-explosion-source underwater explosion shock wave in the flow field.

[0052] Figure 5 It is a schematic diagram of the evolution of the cavitation characteristics of the flow field under the action of the double-explosion-source underwater explosion shock wave. Detailed Embodiments

[0053] The present invention proposes a numerical calculation method for the propagation and cavitation characteristics of double-explosion-source underwater explosion shock waves. This method uses the local discontinuous Galerkin (LDG) method to solve the propagation process of far-field underwater double-explosion-source explosion shock waves in a two-dimensional acoustic flow field, and then studies the cavitation characteristics of the flow field under the action of double-explosion-source underwater explosion shock waves. The dynamic pressure results of the flow field calculated by this method are compared with the calculation results of the acoustic finite element method. The results show that the dynamic pressure results of the flow field calculated by this method are in good agreement with the calculation results of the acoustic finite element method, verifying the effectiveness and accuracy of this method.

[0054] The following will further introduce the detailed embodiments and the technical difficulties and inventive points of the present invention in combination with the design examples of the present invention.

[0055] The specific implementation steps of the present invention are as follows.

[0056] Step 1, based on the research conditions of the double-explosion-source underwater explosion shock cavitation load, by setting the flow field range and its size parameters, establish a flow field calculation model, and discretize to obtain node and element information. Then, the program reads the relevant information of the discretized flow field model. This provides basic data for further calculations based on the discretized flow field;

[0057] First, establish the position and size of the flow field in the finite element software. Use the finite element software to discretize the entire flow field model into triangular meshes, and each triangular mesh forms a unit. Export the discrete flow field file, and the program reads the exported discrete flow field file. The program mainly reads the numbers and coordinate positions of each node and the node composition of each unit, and uses to represent the discretized triangular element flow field.

[0058] Step 2: Based on the relevant information of the discrete element flow field obtained in Step 1. Refer to Figure 2 , set the position of the explosive placement and the position of the explosion point in the flow field, and calculate the distance between the explosive source point and the explosion point:

[0059] (1)

[0060] In the formula, represents the vector position coordinate of the th explosive source point, represents the vector position coordinate of the th explosive explosion point, R 0i represents the distance between the i th explosive source point and the explosion point.

[0061] Step 3: Based on the relevant information of the discrete element flow field in Step 1 and the position of the explosive placement in Step 2. Combine Figure 2 , set the position of the incident wave loading surface in the flow field, and calculate the distance between any point on the incident wave loading surface in the flow field and the explosive source point:

[0062] (2)

[0063] In the formula, x ji represents the vector position coordinate of the point of the i th explosive on the incident wave loading surface, represents the vector position coordinate of the th explosive source point, R ji represents the distance between any point on the incident wave loading surface corresponding to the i th explosive and the explosive source point.

[0064] Step 4: Based on the relevant information of the discrete element flow field in Step 1, the distance between the explosive source point and the explosion point in Step 2, and the distance between any point on the incident wave loading surface in the flow field and the explosive source point in Step 3. Calculate the gradient j of the dynamic pressure in the spatial direction at any point x ;

[0065] For far - field underwater explosion, the explosion source is located outside the flow field. When the explosion source detonates, the generated shock - wave load is applied to the incident - wave boundary of the flow field, thereby realizing the simulation of the propagation process of the underwater - explosion shock wave in the flow field. The underwater - explosion incident wave at any point \(x\) on the incident - wave loading surface of the discrete - element flow field j The calculation formula is as follows:

[0066] (3)

[0067] In the formula, is the delay time, , c is the propagation speed of the shock wave in the flow field, , is the bulk modulus of the fluid, is the density of the fluid. is the load - amplitude value of the explosive at the explosion point. represents the spatial variation of the pressure - field load at any point \(x\) on the incident - wave loading surface j ;

[0068] For the shock wave generated by the underwater explosion of the explosive, the present invention adopts the Geers - Hunter model to describe the attenuation characteristics of the cylindrical wave of the underwater - explosion shock wave in the flow field. Combining Figure 2 , the time - load data of the two explosive explosions at the explosion points in the discrete - element flow field are calculated respectively p t1 and p t2 . After the calculation is completed, the time - load data p t1 and p t2 at the explosion points are imported into the program. The program reads the time - load data p t1 and p t2 of the explosive explosion at the explosion points in the discrete - element flow field. In the present invention, the incident - wave loading surfaces of the two explosives are the same plane. Using the wave - superposition principle, the pressure gradients of the two explosives on the incident - wave loading surface are coupled and superposed to calculate the spatial gradient j of the dynamic pressure at any point \(x\) on the incident - wave loading surface of the discrete - element flow field :

[0069] (4)

[0070] (5)

[0071] In the formula ṗ ti represents the i th time - load data of the explosivep ti The derivative with respect to time, g Ni Represents the i Spatial gradient of the dynamic pressure on the incident wave loading surface generated by the shock wave of the

[0072] Step 5: Based on the discrete element flow field related information in Step 1, the distance between the explosive source point and the detonation point in Step 2, the distance between any point on the incident wave loading surface of the flow field and the explosive source point in Step 3, and the spatial gradient result of the dynamic pressure at any point x j On the incident wave loading surface of the double-explosive source, the boundary conditions of the calculation domain are characterized, and then a numerical model for the propagation of the underwater explosion shock wave of the double-explosive source in the acoustic flow field is constructed to study the propagation law of the underwater explosion shock wave in the flow field;

[0073] The fluid disturbed by the underwater explosion shock wave can be regarded as an inviscid, compressible, and adiabatic fluid. The propagation of the underwater explosion shock wave in the fluid satisfies the second-order wave equation, and the calculation formula of the second-order wave equation in the discrete element flow field Ω Is:

[0074] (6)

[0075] In the formula, p Is the dynamic pressure of the fluid, Δ represents the Laplace operator, Represents the second derivative of the dynamic pressure of the fluid with respect to time;

[0076] The flow field is established in a two-dimensional Cartesian coordinate system to study the propagation characteristics of the underwater explosion shock wave in a two-dimensional watershed. In the Cartesian coordinate system, the calculation formula (6) can be written as:

[0077] (7)

[0078] (8)

[0079] (9)

[0080] In the formula, Represents the derivative operation symbol, Represents the partial derivative of the fluid dynamic pressure with respect to x Direction, Represents the partial derivative of the fluid dynamic pressure with respect to y Direction, Represents the second partial derivative of the fluid dynamic pressure with respect to x Direction, Represents the second partial derivative of the fluid dynamic pressure with respect to y Direction;

[0081] The LDG method is used to solve the propagation of the underwater explosion shock wave load of a double explosion source in a two-dimensional acoustic flow field in a semi-discrete format. The test function is multiplied on both sides of the calculation equation. , and , and the integration is carried out in the discrete element. The control equation for the propagation of the underwater explosion shock wave of the double explosion source in the discrete element acoustic flow field is:

[0082] (10)

[0083] In the formula, is the element e in the discrete element flow field, is the boundary of the element e in the discrete element flow field; U is the matrix composed of the second-order partial derivative of the dynamic pressure in the flow field with respect to time and the partial derivatives of the dynamic pressure in the flow field with respect to the spatial directions x , y ;

[0084] ;

[0085] ;

[0086] ;

[0087] Among them represents the basis function describing the spatial physical quantity in the element, N is the total number of basis functions in an element; j is the index of the basis function, used to identify the j th basis function in the basis function matrix; represents the value of the corresponding physical quantity at the j th basis function of the element; p is the dynamic pressure in the flow field; x and y represent the directions of the two-dimensional Cartesian coordinate system of the flow field; represents the partial derivative of the fluid dynamic pressure with respect to time; represents the second-order partial derivative of the fluid dynamic pressure with respect to time. and are the numerical fluxes of each item in F and G on the element boundary in the matrix. , among which , and are test functions. represents the partial derivative of the test function with respect to the x direction; represents the partial derivative of the test function with respect to the y direction.

[0088] Step 6: Based on the discrete element flow field related information in Step 1 and the control equation for the propagation of the double-explosion-source underwater explosion shock wave in the discrete element acoustic flow field in Step 5, calculate the numerical flux at the boundary of the discrete element flow field. The solution expressions for the numerical flux under different boundary conditions are as follows:

[0089] (11)

[0090] (12)

[0091] (13)

[0092] In the formula, + represents the physical quantity located on the element K , and – represents the physical quantity of another element adjacent to the side K of the element e . is the unit outer normal vector of the element boundary, represents the dynamic pressure at the side K of the element e , represents the time derivative of the fluid dynamic pressure at the non-reflecting boundary element. , where is the length of the side e ; is the gradient of the dynamic pressure in the space direction on the incident wave loading surface.

[0093] Step 7: Based on the various calculations completed in Steps 1 - 6, obtain the dynamic pressure result of the discrete element flow field, introduce a pressure truncation model to handle the cavitation effect, and determine the location where the cavitation region appears in the flow field, specifically:

[0094] (14)

[0095] (15)

[0096] (16)

[0097] In the formula, p is the dynamic pressure in the flow field, is the pseudo-dynamic pressure, is the displacement of the fluid particle, is the absolute pressure at the flow field calculation point, is the atmospheric pressure, is the fluid density, is the gravitational acceleration, is the water depth at the calculation point, is the cavitation limit, and the cavitation limit is set to 0, indicating that the fluid cannot transmit negative pressure.

[0098] Step 8. Based on the data obtained from the relevant calculations and processing completed in Steps 2-7, the physical quantities of all elements in the discrete element flow field at the initial moment can be obtained. The fourth-order Runge-Kutta method is used to calculate the physical quantities of all elements in the discrete element flow field at the next moment. By continuously looping this step in the time domain, the calculation results of the dynamic pressure and total pressure of all discrete elements in the flow field at all calculation time steps are finally obtained, thereby realizing the evolution simulation of the propagation characteristics and cavitation characteristics of the underwater explosion shock wave of a double explosion source in the acoustic flow field.

[0099] Introduce auxiliary variables , , and , Equation (10) can be expressed as:

[0100] (17)

[0101] Combined with the initial conditions , ;

[0102] Use the fourth-order Runge-Kutta method to solve the physical quantities at the next time step, and the calculation expression is:

[0103] (18)

[0104] (19)

[0105] (20)

[0106] (21)

[0107] (22)

[0108] In the formula, Δ t is the time step increment; is the fluid dynamic pressure at t m moment and the first derivative of the fluid dynamic pressure with respect to time; , , , respectively represent the fluid dynamic pressure calculated under different moments and different conditions and the first derivative of the fluid dynamic pressure with respect to time; is the t m value of and at is the calculated when calculating and value, is the Calculated at and value, For calculating Calculated at and value; Is t m +Δ t The hydrodynamic pressure at the moment and the first derivative of the hydrodynamic pressure with respect to time.

[0109] The method of the present invention can accurately simulate the propagation characteristics, interaction mechanism and coupling effect of shock waves during the underwater explosion of a double explosion source, and can effectively simulate the resulting complex cavitation phenomenon, providing a more reliable numerical tool for deeply understanding the mechanism of underwater explosion of a double explosion source and evaluating its damage effect. The present invention can more accurately simulate the propagation process of shock waves generated by the explosion of a double explosion source, effectively suppress the numerical oscillation of the pressure curve, and improve the accuracy and credibility of the simulation of shock wave propagation. In addition, the method of the present invention can be used to systematically study the effects of parameters such as the detonation distance, mass ratio between the two explosives, and the detonation time of the two explosives on the cavitation characteristics of the flow field, reveal the evolution law and intensity of cavitation phenomena under different parameter combinations, and provide a theoretical basis and design reference for underwater explosion engineering applications, such as underwater weapon design and underwater blasting operation optimization.

[0110] In order to verify the effectiveness of the LDG method described in the present invention in simulating the propagation and cavitation characteristics of shock waves during the underwater explosion of a double explosion source, the results of the calculation method adopted in the present invention are compared with the results calculated by the acoustic finite element method. The dynamic pressure at a point on the central axis of the two explosives in the flow field is selected for comparison. As Figure 3 shown, the results show that: the dynamic pressure results of the calculation method adopted in the present invention are in good agreement with the results calculated by the acoustic finite element method. Compared with the traditional acoustic finite element method, the LDG method described in the present invention effectively suppresses the numerical oscillation of the pressure curve and obtains a smoother shock wave pressure time history curve. This characteristic indicates that the LDG method described in the present invention can more truly reflect the physical essence during the propagation process of shock waves during the underwater explosion of a double explosion source, providing reliable technical support for the numerical simulation of shock wave problems during the underwater explosion of a double explosion source.

[0111] Figure 4 Shows the propagation process of shock waves generated by two 0.5 kg TNT explosives in a 45 m × 16 m two-dimensional computational domain simulated using the calculation method of the present invention. When t = 1.2 ms, the shock waves generated by the explosion of the two explosives enter the flow field. When t = 7.76 ms, the shock waves generated by the explosion of the two explosives continue to propagate far away in the flow field. When tAt \(t = 11.28\) ms, the shock waves generated by the two explosives contact the free surface of the flow field and generate rarefaction waves. When t At \(t = 17.68\) ms, the generated rarefaction waves propagate in the flow field along the direction opposite to the shock waves.

[0112] Figure 5 Shows the evolution characteristics of the cavitation region (red region) in the flow field during the propagation of shock waves generated by two 0.5 kg TNT explosives in a 45 m × 16 m two-dimensional computational domain simulated using the calculation method of the present invention.

[0113] Figure 4 and Figure 5 Shows the propagation process of shock waves (unit: Pa) and the evolution characteristics of the cavitation region (red region) at different times during the simulation of two 0.5 kg TNT explosives in a 45 m × 16 m two-dimensional computational domain using the calculation method of the present invention. This fully demonstrates that the present invention has the ability to accurately simulate the interaction, attenuation law of underwater explosion shock waves of double explosion sources, and the cavitation characteristics of the flow field.

[0114] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

[0115] Although the specific implementation manners of the present invention are described above, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that based on the technical solutions of the present invention, various modifications or deformations that can be made without creative efforts by those skilled in the art are still within the protection scope of the present invention.

Claims

1. A numerical calculation method for underwater explosion shock cavitation load with double explosion sources, characterized in that It includes the following processes: Step 1: Based on the double-explosion-source underwater explosion shock cavitation load condition, by setting the flow field range and its size parameters, establish a flow field model, and discretize the flow field model into grid units to obtain relevant information on the discrete unit flow field; Step 2: Based on the relevant information of the discrete unit flow field, the position where the explosive is placed, and the explosion point position in the flow field, calculate the distance between the explosive source point and the explosion point; Step 3: Set the position of the incident wave loading surface of the flow field, and calculate the distance between any point on the incident wave loading surface of the flow field and the explosive source point; Step 4, calculate the gradient of the dynamic pressure in any spatial direction at any point x on the incident wave loading surface of the flow field based on the relevant information of the discrete element flow field, the distance between the explosive source point and the detonation point, and the distance between any point on the incident wave loading surface of the flow field and the explosive source point j at the place ; Step 5: Based on the results of Steps 1 to 4, characterize the boundary conditions at the incident wave loading surface of the double-explosion-source calculation domain, and construct a numerical model for the propagation of the double-explosion-source underwater explosion shock wave in the acoustic flow field; The control equation for the propagation of the double-explosion-source underwater explosion shock wave in the discrete unit acoustic flow field is: In the formula, is the unit in the discrete element flow field e , is the boundary of the unit e in the discrete element flow field. where represents the basis function for the spatial physical quantity in the description unit, N is the total number of basis functions in a unit; j is the index of the basis function, used to identify the j th basis function in the basis function matrix; represents the value of the corresponding physical quantity at the j th basis function of the unit; p is the dynamic pressure in the flow field; x and y represent the directions of the two-dimensional Cartesian coordinate system of the flow field; represents the partial derivative of the fluid dynamic pressure with respect to time; represents the second-order partial derivative of the fluid dynamic pressure with respect to time; represents the partial derivative of the fluid dynamic pressure with respect to the x direction; represents the partial derivative of the fluid dynamic pressure with respect to the y direction; and are the numerical fluxes of the terms in F and G in the matrix on the unit boundary; , where , and are the test functions; represents the partial derivative of the test function with respect to the x direction; represents the partial derivative of the test function with respect to the y direction; Step 6: Based on the phase information of the discrete unit flow field in Step 1 and the control equation for the propagation of the double-explosion-source underwater explosion shock wave in the discrete unit acoustic flow field, calculate the numerical flux at the boundary of the discrete unit flow field to obtain the numerical flux at the boundary of the discrete unit flow field; Step 7: Introduce a pressure truncation model to handle the cavitation effect, identify the region where the absolute pressure of the flow field is lower than the cavitation limit, and obtain the position result of the cavitation region in the flow field; Step 8: After calculating the physical quantities of all units in the discrete unit flow field at the initial moment based on the above process, calculate the physical quantities of all units in the discrete unit flow field at the next moment; By continuously looping this step in the time domain, finally obtain the calculation results of the dynamic pressure and total pressure of all discrete units in the flow field at all calculation time steps.

2. A numerical calculation method for double-explosion-source underwater explosion shock cavitation load according to claim 1, characterized in that: The relevant information of the discrete unit flow field in Step 1 is obtained by the program reading the node numbers, coordinate positions, and node information of each unit in the flow field model.

3. The numerical calculation method for the underwater explosion shock cavitation load of a double explosion source according to claim 1, characterized in that: The specific calculation method of Step 2 is: In the formula, represents the vector position coordinates of the th explosive source point, represents the vector position coordinates of the th explosive detonation point, R 0i represents the distance between the i th explosive source point and the detonation point.

4. A numerical calculation method for underwater explosion shock cavitation load with double explosion sources according to claim 1, characterized in that: The specific calculation method of Step 3 is: where x ji represents the vector position coordinates of the point of the i th explosive on the incident wave loading surface, represents the vector position coordinates of the th explosive source point, R ji represents the distance between any point on the incident wave loading surface corresponding to the i th explosive and the explosive source point.

5. A numerical calculation method for double-explosion-source underwater explosion shock cavitation load according to claim 1, characterized in that: Step 4 is specifically: The calculation formula for any point x on the incident wave loading surface of the underwater explosion incident wave in the discrete element flow field is as follows: j where: In the formula, is the delay time, , c is the propagation speed of the shock wave in the flow field, , is the bulk modulus of the fluid, is the fluid density; is the load amplitude value of the explosive at the explosion point; represents the spatial variation of the pressure field load at any point x j on the incident wave loading surface; The incident wave loading surfaces of the two explosives are the same plane. Using the wave superposition principle, the pressure gradients of the two explosives on the incident wave loading surface are coupled and superimposed to calculate the spatial gradient of the dynamic pressure at any point x on the incident wave loading surface of the discrete element flow field j where the dynamic pressure is located .

6. The numerical calculation method for double-explosion-source underwater explosion shock cavitation load according to claim 1, characterized in that: In Step 6, when calculating the numerical flux at the boundary of the discrete unit flow field, the numerical flux solution expressions under different boundary conditions are as follows: where + represents the physical quantity located at the element K and – represents the physical quantity of another element adjacent to the edge K of the element e ; is the unit outer normal vector of the element boundary, represents the dynamic pressure at the edge K of the element e , represents the time derivative of the fluid dynamic pressure at the non-reflective boundary element; , where is the length of the edge e .

7. A numerical calculation method for underwater explosion shock cavitation load with double explosion sources as described in claim 1, characterized in that: In Step 7, when calculating the position where the cavitation region appears in the flow field, it is specifically: In the formula, p is the dynamic pressure in the flow field, is the pseudo-dynamic pressure, is the displacement of the fluid particles, is the absolute pressure at the flow field calculation point, is the atmospheric pressure, is the fluid density, is the acceleration due to gravity, is the water depth at the calculation point, is the cavitation limit, and the cavitation limit is set to 0, indicating that the fluid cannot transmit negative pressure.

8. The numerical calculation method of the underwater explosion shock cavitation load with double explosion sources as described in claim 1, characterized in that: Step 8 uses the fourth-order Runge-Kutta method to calculate the physical quantities of all units in the discrete unit flow field at the next moment.

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