Calculation method suitable for full-sea-depth underwater explosive shock wave and bubble load

Abstract

The invention discloses a calculation method suitable for full-sea-depth underwater explosion shock waves and bubble loads, and relates to the field of underwater explosion. The method solves the problems that a double-exponential formula in a shock wave stage of an existing theoretical model for underwater explosion load calculation cannot reflect the attenuation rule of shock wave pulse width and water depth and does not conform to the actual situation. The method comprises the following steps: setting a working condition of underwater explosion, and determining an initial condition required by calculation; the method comprises the following steps: calculating an underwater explosion shock wave load based on an intermittent Galerkin method under a spherical symmetric projection coordinate system, switching underwater explosion load calculation from a shock wave stage to a bubble stage, and switching a shock wave load calculation method to a far-field shock wave propagation model solved by adopting the intermittent Galerkin method; and solving the bubble equation by adopting a Runge-Kutta method to obtain a physical quantity of underwater explosion, calculating a bubble load at a specified measuring point in water based on a potential flow theory, and calculating full-sea deep-water underwater explosion shock wave and the bubble load.

Description

Technical Field

[0001] The invention relates to the technical field of underwater explosion, and in particular to a calculation method for shock waves and bubble loads of underwater explosions at full sea depth. Background Art

[0002] In recent years, rapid progress has been made in the field of deep-sea exploration and development. In order to ensure the safety of deep-sea submersibles and structures, external loads in the deep-sea environment must be considered. As an external load in the deep-sea environment that can cause significant damage to submersibles and structures, accurate calculation of underwater explosion loads is of great significance. At present, the calculation of underwater explosion loads, especially explosion loads in deep-water environments, generally relies on two calculation methods: numerical simulation and theoretical models. For the calculation of underwater explosion loads in a free field, the theoretical model requires less computing resources and shorter calculation time than the numerical simulation. Therefore, it is of great utility to innovate the theoretical model and improve the accuracy of the theoretical model calculation.

[0003] The widely used theoretical model for underwater explosion load calculation is the Geers-Hunter model, which divides the underwater explosion load into the shock wave stage and the bubble stage. In the shock wave stage, the double exponential empirical formula is used to calculate the shock wave load, and in the bubble stage, the double asymptotic method is used to solve the Hicks equation. It has acceptable accuracy under conventional underwater explosion conditions. However, the existing Geers-Hunter model has the following problems:

[0004] 1. The double exponential empirical formula used in the shock wave stage cannot reflect the attenuation law that the shock wave pulse width decreases with the increase of water depth. The shock wave pulse width of the double exponential empirical formula in deep water environment is obviously larger than the actual situation;

[0005] 2. When switching from the shock wave stage to the bubble stage, the pressure curve obtained based on the double exponential empirical formula cannot be guaranteed to maintain a smooth connection with the pressure curve calculated based on the initial conditions of the bubble stage determined by the double exponential empirical formula, resulting in a pressure jump that is inconsistent with the actual physical situation.

[0006] 3. When switching from the shock wave stage to the bubble stage, the initial conditions of the bubble stage determined based on the empirical formula will introduce errors into subsequent calculations, causing errors in the calculation of the bubble load. Summary of the invention

[0007] The present invention aims to solve the problems that the theoretical Geers-Hunter model for underwater explosion load calculation in the prior art has a double exponential empirical formula used in the shock wave stage that cannot reflect the attenuation law that the shock wave pulse width decreases with increasing water depth and is inconsistent with the actual situation; and when switching from the shock wave stage to the bubble stage, the pressure curve obtained based on the double exponential empirical formula cannot ensure smooth connection with the pressure curve calculated based on the initial conditions of the bubble stage determined by the double exponential empirical formula, resulting in a pressure jump that is inconsistent with the actual physical situation; the initial conditions of the bubble stage determined based on the empirical formula will introduce errors into subsequent calculations, resulting in errors in the calculation of the bubble load.

[0008] To solve the above technical problems, the present invention is achieved through the following technical solutions:

[0009] The present invention proposes a calculation method for full-sea-depth underwater explosion shock wave and bubble load, the calculation method comprising the following steps:

[0010] S1. Set the working conditions of underwater explosion as needed to determine the initial conditions required for calculation;

[0011] S2. According to the initial conditions obtained in S1, the shock wave load of the underwater explosion is calculated based on the discontinuous Galerkin method in a spherically symmetric projection coordinate system to obtain a shock wave load curve with an attenuation law;

[0012] S3, based on the shock wave load curve of the attenuation law obtained in S2, the underwater explosion load calculation is switched from the shock wave stage to the bubble stage, and the calculation method of the shock wave load is switched to the far-field shock wave propagation model solved by the discontinuous Galerkin method;

[0013] S4. According to the initial conditions of the bubble load obtained in S2, the bubble equation of the same form is solved by using the Runge-Kutta method to obtain the physical quantities of the underwater explosion, which include the radius R of the spherical bubble. b , the time derivative of the radius Second derivative of radius with respect to time Migration Z, migration speed v, migration acceleration

[0014] S5. According to the physical quantities of the underwater explosion obtained in S4, the bubble load at the specified measuring point in the water is calculated based on the potential flow theory, and the shock wave and bubble load of the underwater explosion at full sea depth are calculated.

[0015] Further, a preferred embodiment is provided, wherein the working conditions of the underwater explosion in S1 include overall arrangement, bubble parameters, and material parameters;

[0016] The overall layout includes the explosive mass W, the explosion water depth h, the horizontal coordinate x of the measuring point, the vertical coordinate z of the measuring point, and the end time t end , step size κ, delay time t ε ;

[0017] Bubble parameters include dynamic viscosity μ, surface tension σ, cavitation limit p c , gravitational acceleration g, drag resistance coefficient β, additional mass coefficient α, free surface reflection coefficient η;

[0018] The material parameters are the JWL state equation parameters A, B, ω, R1, R2, ρ0 and E0 of the explosive used.

[0019] Further, a preferred embodiment is provided, wherein S1 also includes obtaining the radius R of the spherical explosive in the shock wave stage according to the explosive mass W and the JWL state equation parameter ρ0 c , according to the measuring point abscissa x and ordinate z in S1, the measuring point distance r = D in the spherically symmetric coordinate system is obtained, and according to the JWL state equation parameters of the explosive in S1, the initial pressure P in the bubble is obtained g0 steps.

[0020] Further, a preferred embodiment is provided to obtain the radius R of the spherical explosive in the shock wave stage c , the distance between the measuring points in the spherically symmetric coordinate system r = D, the initial pressure inside the bubble P g0 The method is:

[0021]

[0022] Further, a preferred embodiment is provided, wherein the spherically symmetric projection coordinate system described in S2 is a natural spherically symmetric coordinate system r with the center of the spherical explosive as r=0 and the surface of the spherical bubble generated by the underwater explosion as r=R b The coordinate position is λ = 0, and the position of the spherical shock wave produced by the underwater explosion of the spherical explosive is r = R s is a spherically symmetric projection coordinate system with coordinate λ = 1

[0023] Further, a preferred implementation manner is provided, in which the method for calculating the underwater explosion shock wave load based on the discontinuous Galerkin method in a spherically symmetric projection coordinate system in S2 is:

[0024]

[0025] in, is the derivative of the given physical quantity with respect to t when λ remains constant, which is expanded into

[0026] Further, a preferred embodiment is provided, in which the condition for switching the underwater explosion load calculation from the shock wave stage to the bubble stage in S3 is: with the center of the spherical explosive as the center, when the radius R of the spherical shock wave surface generated by its explosion is s Greater than the radius R of the spherical bubble produced by its explosion at this moment b 10 times, that is, R s >10R b .

[0027] Further, a preferred embodiment is provided, in which the far-field shock wave propagation model described in S3 is:

[0028]

[0029] Where, L domain is the length of the computational domain, Y c =(γ-1) / 2ρ ∞ C ∞ , γ = 7.15 is the specific heat ratio of water, C is the speed of sound in the flow field, where C ∞ =1500m / s is the speed of sound in the undisturbed water medium, δp is the flow field disturbance pressure, is the shock wave propagation velocity in the natural spherically symmetric coordinate system r.

[0030] Further, a preferred embodiment is provided, the bubble equation of the same form described in S4 is:

[0031]

[0032] Where N is the enthalpy difference between the inner and outer surfaces of the bubble.

[0033] Further, a preferred implementation manner is provided, in S5, based on the potential flow theory, the bubble load at the specified measuring point in the water is calculated, and the method for calculating the shock wave and bubble load of the underwater explosion at full sea depth is:

[0034]

[0035] Substituting the value of the physical quantity at time t into the above formula, the bubble load at the measuring point is obtained.

[0036] The present invention is beneficial in that:

[0037] The method for calculating shock wave and bubble loads of underwater explosions at full sea depth described in the present invention solves the shock wave load directly in a spherically symmetric projection coordinate system from the first principles, thereby ensuring that accurate results of the shock wave load and the correct attenuation law of the shock wave pulse width are obtained, thereby avoiding the generation of non-physical pressure jumps.

[0038] The method for calculating shock wave and bubble loads of underwater explosions at full sea depth described in the present invention provides accurate initial conditions for calculating bubble loads by directly solving shock wave loads, and can show higher accuracy than the commonly used Geers-Hunter model, especially near the water surface and in the deep sea.

[0039] The method for calculating shock waves and bubble loads of underwater explosions at full sea depth described in the present invention solves a bubble equation with a unified form in the bubble stage, and can consider the influence of physical factors such as boundaries, gravity, environmental flow fields and migration compressibility.

[0040] The present invention is also applicable to the field of accuracy verification of full-sea-depth underwater explosion shock waves and bubble loads calculated by other numerical simulation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The present invention is a flowchart of a method for calculating shock waves and bubble loads of underwater explosions at full sea depth, according to an embodiment of the present invention.

[0042] Figure 2 A schematic diagram of a spherically symmetric projection coordinate system for a calculation method of full-sea-depth underwater explosion shock waves and bubble loads according to an embodiment of the present invention.

[0043] Figure 3 This is a schematic diagram of the comparison results of the load time history curve of 0.227 kg of TNT at a measuring point 0.69 m away from an explosion at 182.88 m underwater according to an embodiment of the present invention.

[0044] Figure 4 This is a schematic diagram of the comparison results of the time history curve of the explosion bubble radius of 0.227 kg of TNT at 182.88 meters underwater according to the embodiment of the present invention.

[0045] Figure 5 This is a schematic diagram of the comparison results of the load time history curves of the measuring point at a distance of 1285 meters when 0.453 kg of TNT exploded 1341 meters underwater according to the embodiment of the present invention.

[0046] Figure 6 It is a schematic diagram of the comparison results of the load time history curve of 0.453 kg of TNT at a measuring point at a distance of 2169 meters and 2225 meters underwater according to the embodiment of the present invention.

[0047] Figure 7 This is a schematic diagram of the comparison results of the load time history curves of the measuring point at a distance of 4241 meters and 4298 meters underwater when 0.453 kg of TNT exploded according to the embodiment of the present invention.

[0048] Figure 8This is a schematic diagram of the comparison results of the load time history curves of the measuring point at a distance of 1285 meters when 25.85 kg of TNT exploded 1341 meters underwater according to the embodiment of the present invention.

[0049] Fig. 9 Schematic diagram of pulse width attenuation of underwater explosion shock wave according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solutions and advantages of the implementation methods of the present application clearer, the technical solutions in the implementation methods of the present application will be clearly and completely described below in conjunction with the drawings in the implementation methods of the present application. Obviously, the described implementation methods are only part of the implementation methods of the present application, not all of the implementation methods.

[0051] See also Figures 1 to 9 This embodiment describes a method for calculating shock waves and bubble loads of underwater explosions at full sea depth. This embodiment is based on underwater explosion conditions. The initial conditions for calculation are determined by giving the overall layout, bubble parameters, and material parameters. The shock wave load is directly calculated in a spherically symmetric projection coordinate system from the first principles. After the conditions for switching from the shock wave stage to the bubble stage are met, the calculated results are used as the initial conditions for the bubble stage, and the Runge-Kutta method is then used to solve the bubble equation in a unified form. Finally, the bubble load at the measuring point is obtained based on the potential flow theory.

[0052] See also Figure 1 As shown, a calculation method for shock waves and bubble loads of underwater explosions at full sea depth specifically includes the following steps:

[0053] S1. Set the working conditions of underwater explosion as required to determine the initial conditions required for calculation;

[0054] The S1 specifically includes the following steps:

[0055] S1.1 Determine the explosive mass W, explosion water depth h, measuring point abscissa x, measuring point ordinate z, and end time t end , step size κ, delay time t ε The overall arrangement of the dynamic viscosity μ, surface tension σ, cavitation limit p c , gravity acceleration g, drag resistance coefficient β, additional mass coefficient α, free surface reflection coefficient η and other bubble parameters, determine the material parameters such as JWL state equation parameters A, B, ω, R1, R2, ρ0 and E0 of the explosive used;

[0056] S1.2 According to the explosive mass W in S1.1 and the JWL state equation parameter ρ0 of the explosive, the radius R of the spherical explosive in the shock wave stage is obtained. cAccording to the horizontal coordinate x and vertical coordinate z of the measuring point in S1.1, the distance r=D between the measuring points in the spherically symmetric coordinate system is obtained. According to the JWL state equation parameters of the explosive in S1.1, the initial pressure P in the bubble is obtained. g0 , R c , D and P g0 The calculation method of is as follows:

[0057]

[0058] S2. According to the initial conditions obtained in S1, the underwater explosion shock wave load is calculated based on the discontinuous Galerkin method in a spherically symmetric projection coordinate system to obtain a shock wave load curve with a correct attenuation law, and provide accurate initial conditions for the calculation of bubble loads;

[0059] The S2 specifically includes the following steps:

[0060] S2.1. In the natural spherical symmetric coordinate system r with the center of the spherical explosive as the origin, the surface of the spherical bubble produced by the underwater explosion of the explosive r = R b λ = 0, the spherical shock wave produced by the underwater explosion of explosives is r = R s For λ=1, establish a spherically symmetric projection coordinate system λ;

[0061] S2.2. Based on S2.1, the velocity u in the natural spherically symmetric coordinate system r and the corresponding velocity U in the projected coordinate system λ are calculated as follows:

[0062]

[0063] S2.3. The Euler equations to be solved by the discontinuous Galerkin method in the spherically symmetric projection coordinate system λ established in S2.2 are expressed as follows:

[0064]

[0065] In the above formula: is the derivative of the given physical quantity with respect to t when λ remains constant, which can be expanded as

[0066] S2.4, to close the Euler equations in S2.3, the Tamman state equation is used for the ambient flow field, and the JWL state equation is used for the gas in the underwater explosion bubble. The two are expressed as follows:

[0067] p l =ρE(γ-1)-γP w

[0068]

[0069] In the above formula: γ = 7.15 is the specific heat ratio of water, P w =3.309×10 8 Pa is the reference pressure;

[0070] S2.5. The pressure distribution condition in the natural spherically symmetric coordinate system r is:

[0071]

[0072] In the above formula: p l (λ,t) is the flow field pressure obtained in the spherically symmetric projection coordinate system λ, ρ ∞ =1000kg / m 3 is the flow field density at the undisturbed location;

[0073] S2.6, in order to establish the coordinate system in S2.1 and provide the initial boundary conditions for the calculation of the shock wave load, considering that the speed of shock wave propagation in water is much greater than the expansion speed of spherical bubbles, the delay time t determined in S1.1 for the shock wave propagation in water is set to ε , so that the shock wave surface r = R s With the spherical bubble surface r = R b Separate and then establish the spherically symmetric projection coordinate system λ. At this time, the radius of the spherical bubble R bε and the shock wave radius R sε As shown below:

[0074]

[0075] In the above formula: u(λ,t ε ) is t=t ε Fluid velocity at the moment, C ∞ =1500m / s is the speed of sound in the undisturbed flow field;

[0076] S2.7. Solve for the shock wave velocity in S2.6 It needs to be obtained according to the Hugoniot condition, as shown below:

[0077]

[0078] S2.8, fluid velocity u(λ,t ε ) is obtained from the following relationship:

[0079]

[0080] S2.9. The fluid density in the Euler equations described in S2.3 is expressed as follows:

[0081]

[0082] S2.10. The boundary conditions required to solve the Euler equations described in S2.3 are:

[0083]

[0084] S3, based on the shock wave results obtained in S2, when R s >10R b When t=t, the underwater explosion load calculation is switched from the shock wave stage to the bubble stage, and the time when the switching condition is satisfied is taken as t=t e , and at the same time, the calculation method of the shock wave load is switched to the far-field shock wave propagation model solved by the discontinuous Galerkin method;

[0085] The S3 specifically includes the following steps:

[0086] S3.1. The state equation of the ambient flow field in the far-field shock wave propagation model adopts the Tait state equation as shown below:

[0087]

[0088] S3.2. According to the Tait state equation in S3.1, the actual sound velocity C of the flow field disturbed by the shock wave can be obtained as follows:

[0089]

[0090] S3.3, the actual sound velocity C obtained in S3.2 is at p = ρ ∞ gh to expand and make and δp=p-ρ ∞ gh, and ignore the resulting high-order small quantity o(δp) 2 , the simplified expression of the actual sound speed C can be obtained as follows:

[0091] C=C ∞ +Y c δp;

[0092] S3.4. The energy conservation equation of the shock wave can be simplified as follows:

[0093]

[0094] In the above formula: The shock wave energy E can be approximated as

[0095] S3.5. Determine the length L of the computational domain in the far-field shock wave propagation model domain , get the left endpoint R of the computational domain f =R s -L domain ;

[0096] S3.6. Based on the left endpoint of the computational domain obtained in S3.5, a new spherically symmetric projection coordinate system χ is established using a method similar to that in S2 as shown below:

[0097]

[0098] S3.7. Substituting the shock wave energy conservation equation in S3.4 into the spherically symmetric projection coordinate system χ established in S3.6, the energy conservation equation shown below can be obtained:

[0099]

[0100] S3.8. Establishing Flux The energy conservation equation in S3.7 can be rewritten as follows:

[0101]

[0102] S3.9. The boundary conditions required to solve S3.8 are as follows:

[0103]

[0104] S4. According to the initial conditions of the bubble load obtained in S2, the bubble equation with a unified form is solved by the Runge-Kutta method to obtain the radius R of the underwater explosion spherical bubble b , the time derivative of the spherical bubble radius Second derivative of radius with respect to time Migration Z, migration speed v, migration acceleration etc. physical quantities;

[0105] The S4 specifically includes the following steps:

[0106] S4.1. According to the calculation results in S2, we can directly obtain e At this moment, the initial bubble internal pressure p is used to solve the bubble equation with a unified form b1 , initial bubble radius R b1 , calculated as follows:

[0107] p b1 =P g (t e )

[0108] R b1 =R b (t e );

[0109] S4.2. Derivative of the radius of a spherical bubble with respect to time The energy dissipation of the shock wave is considered according to the following method:

[0110]

[0111] In the above formula: τ is a constant less than 1 used to exclude the energy dissipated by the shock wave in the spherically symmetric projection coordinate system λ. The recommended value here is τ = 0.65;

[0112] S4.3, based on μ, σ determined in S1 and p obtained in S4.1 b1 , determine the initial bubble pressure P g1 As shown below:

[0113]

[0114] S4.4. μ, α, β, g obtained as described in S1 and R obtained as described in S4.1 b1 , obtained as described in S4.2 and P obtained as described in S4.3 g1 Substitute the bubble equation in unified form shown below and solve it using the Runge-Kutta method:

[0115]

[0116] In the above formula: C = 1500m / s is the speed of sound in the flow field;

[0117] S4.5. The displacement Z of the underwater exploding spherical bubble is obtained by integrating the velocity v obtained in the process of solving the bubble equation in the unified form as described in S4.4:

[0118]

[0119] S5. According to the physical quantities obtained in S4, the bubble load at the specified measuring point in the water is calculated based on the potential flow theory, and the bubble load at the measuring point r is obtained as follows:

[0120]

[0121] The method is further described below in conjunction with the results of specific embodiments, and is analyzed by comparison with the commonly used Geers-Hunter model.

[0122] (1) Comparison between conventional underwater explosion shock waves and bubble loads

[0123] Figure 4The results of comparing the experimental data with the method and the Geers-Hunter model for the load at the point of 0.69 m at the explosion distance of 0.227 kg TNT at 182.88 m underwater are given. It can be seen that for conventional underwater explosion shock waves and bubble loads, both the method and the Geers-Hunter model can be well consistent with the experimental results.

[0124] (2) Comparison of conventional underwater explosion bubble radius

[0125] Figure 5 The results of comparing the radius of the bubble produced by the explosion of 0.227 kg of TNT at 182.88 meters underwater with the experimental data and the method and the Geers-Hunter model are given. It can be seen that for the radius change of the bubble of a conventional underwater explosion, both the method and the Geers-Hunter model can be well consistent with the experimental results.

[0126] (3) Comparison of deepwater explosion shock waves and bubble loads

[0127] Figure 5 , Figure 6 , Figure 7 , Figure 8 The results of deepwater explosion shock wave and bubble loads under different working conditions are given, and the experimental data are compared with the method and the Geers-Hunter model. Figure 5 The working condition shown is the load of 0.453 kg TNT at the point of explosion at 1341 meters underwater and 1285 meters away. Figure 6 The working condition shown is the load of 0.453 kg TNT at the point of explosion at 2169 meters at 2225 meters underwater. Figure 7 The working condition shown is the load of 0.453 kg TNT at the point of 4241 meters at the explosion distance of 4298 meters underwater. Figure 8 The working condition shown is the load of the measuring point at a distance of 1285 meters when 25.85 kg of TNT exploded at 1341 meters underwater. It can be seen that this method can greatly improve the calculation accuracy of underwater explosion shock wave and bubble load in deep water, give the correct trend of shock wave pulse width changing with water depth, and effectively reduce the non-physical jump of load when the shock wave stage is connected with the bubble stage.

[0128] (4) Changes of deepwater explosion shock wave pulse width with water depth

[0129] Fig. 9 The variation law of shock wave pulse width of different masses of TNT at different water depths obtained by this method is given. It can be seen that this method can clearly show the law that the pulse width of underwater explosion shock wave decreases with the increase of depth.

[0130] In summary, the present embodiment discloses a calculation method for shock wave and bubble load of underwater explosion at full sea depth. First, the method sets the working conditions of underwater explosion as required to determine the initial conditions required for calculation. Secondly, the shock wave load of underwater explosion is calculated based on the discontinuous Galerkin method in a spherically symmetric coordinate system to obtain a shock wave load curve with a correct attenuation law, and provide accurate initial conditions for the calculation of bubble load. Then, the calculation of underwater explosion load is switched from the shock wave stage to the bubble stage. On this basis, the bubble equation with a unified form is solved by adopting the Runge-Kutta method to obtain physical quantities such as the radius, expansion velocity, expansion acceleration and migration, migration velocity, migration acceleration of underwater explosion spherical bubbles. Finally, the bubble load at a specified measuring point in water is calculated based on the potential flow theory, thereby calculating the shock wave and bubble load of underwater explosion at full sea depth. The present invention provides more accurate shock wave load results for full-sea-depth underwater explosions by using the results calculated by the discontinuous Galerkin method in a spherically symmetric coordinate system, and thereby provides more accurate initial conditions for the bubble stage, thereby ensuring a smooth connection between the shock wave stage and the bubble stage, and also obtaining more accurate bubble load results.

[0131] Those skilled in the art will appreciate that the above are only preferred embodiments of the present invention, and the various embodiments of the present disclosure and / or the features described in the claims may be combined or combined in various ways, even if such combinations or combinations are not explicitly described in the present disclosure. It is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art may still modify the technical solutions described in the aforementioned embodiments, or perform equivalent substitutions on some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

[0132] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A calculation method for shock waves and bubble loads of underwater explosions at full sea depth, characterized in that: The calculation method comprises the following steps: S1. Set the working conditions of underwater explosion as needed to determine the initial conditions required for calculation; S2. According to the initial conditions obtained in S1, the shock wave load of the underwater explosion is calculated based on the discontinuous Galerkin method in a spherically symmetric projection coordinate system to obtain a shock wave load curve with an attenuation law; S3, based on the shock wave load curve of the attenuation law obtained in S2, the underwater explosion load calculation is switched from the shock wave stage to the bubble stage, and the calculation method of the shock wave load is switched to the far-field shock wave propagation model solved by the discontinuous Galerkin method; S4. Based on the initial conditions of the bubble load obtained in S2, the bubble equation of the same form is solved using the Runge-Kutta method to obtain the physical quantities of the underwater explosion, including the radius R of the spherical bubble. b , the time derivative of the radius Second derivative of radius with respect to time Migration Z, migration speed v, migration acceleration S5. According to the physical quantities of the underwater explosion obtained in S4, the bubble load at the specified measuring point in the water is calculated based on the potential flow theory, and the shock wave and bubble load of the underwater explosion at the full sea depth are calculated.

2. The calculation method for full-sea-depth underwater explosion shock wave and bubble load according to claim 1 is characterized in that: The working conditions of underwater explosion in S1 include overall arrangement, bubble parameters, and material parameters; The overall layout includes the explosive mass W, the explosion water depth h, the horizontal coordinate x of the measuring point, the vertical coordinate z of the measuring point, and the end time t end , step size κ, delay time t ε ; Bubble parameters include dynamic viscosity μ, surface tension σ, cavitation limit p c , gravitational acceleration g, drag resistance coefficient β, additional mass coefficient α, free surface reflection coefficient η; The material parameters are the JWL state equation parameters A, B, ω, R1, R2, ρ0 and E0 of the explosive used.

3. The calculation method for full-sea-depth underwater explosion shock wave and bubble load according to claim 2 is characterized in that: S1 also includes the radius R of the spherical explosive in the shock wave stage obtained based on the explosive mass W and the JWL state equation parameter ρ0 c , according to the measuring point abscissa x and ordinate z in S1, the measuring point distance r = D in the spherically symmetric coordinate system is obtained, and according to the JWL state equation parameters of the explosive in S1, the initial pressure P in the bubble is obtained g0 steps.

4. The calculation method for full-sea-depth underwater explosion shock wave and bubble load according to claim 3 is characterized in that: Get the radius R of the spherical explosive in the shock wave stage c , the distance between the measuring points in the spherically symmetric coordinate system r = D, the initial pressure inside the bubble P g0 The method is:

5. The calculation method for full-sea-depth underwater explosion shock wave and bubble load according to claim 1 is characterized in that: The spherically symmetric projection coordinate system described in S2 is a natural spherically symmetric coordinate system r with the center of the spherical explosive as r = 0 and the surface of the spherical bubble generated by the underwater explosion as r = R b The coordinate position is λ = 0, and the position of the spherical shock wave produced by the underwater explosion of the spherical explosive is r = R s is a spherically symmetric projection coordinate system with coordinate λ = 1 6. The calculation method for full-sea-depth underwater explosion shock wave and bubble load according to claim 1 is characterized in that: The method for calculating the underwater explosion shock wave load based on the discontinuous Galerkin method in S2 in the spherically symmetric projection coordinate system is: in, is the derivative of the given physical quantity with respect to t when λ remains constant, which is expanded into 7. The calculation method for full-sea-depth underwater explosion shock wave and bubble load according to claim 1 is characterized in that: The condition for switching the underwater explosion load calculation from the shock wave stage to the bubble stage in S3 is: with the center of the spherical explosive as the center, when the radius R of the spherical shock wave surface generated by its explosion is s Greater than the radius R of the spherical bubble produced by its explosion at this moment b 10 times, that is, R s >10R b .

8. The calculation method for full-sea-depth underwater explosion shock wave and bubble load according to claim 1 is characterized in that: The far-field shock wave propagation model described in S3 is: Where, L domain is the length of the computational domain, Y c =(γ-1) / 2ρ ∞ C ∞ , γ = 7.15 is the specific heat ratio of water, C is the speed of sound in the flow field, where C ∞ =1500m / s is the speed of sound in the undisturbed water medium, δp is the flow field disturbance pressure, is the shock wave propagation velocity in the natural spherically symmetric coordinate system r.

9. The calculation method for full-sea-depth underwater explosion shock wave and bubble load according to claim 1, characterized in that: The bubble equation of the same form as described in S4 is: Where N is the enthalpy difference between the inner and outer surfaces of the bubble.

10. The calculation method for full-sea-depth underwater explosion shock wave and bubble load according to claim 1, characterized in that: In S5, the bubble load at the specified measuring point in the water is calculated based on the potential flow theory. The method for calculating the shock wave and bubble load of the underwater explosion at full sea depth is: Substituting the value of the physical quantity at time t into the above formula, the bubble load at the measuring point is obtained.

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