A method for calculating underwater shock wave and bubble load suitable for full sea depth

Abstract

The application relates to a calculation method suitable for full-sea-depth underwater strong transient shock wave and bubble load, and relates to the field of underwater strong dynamic load. The method solves the problems that the existing underwater strong dynamic load calculation theoretical model cannot reflect the attenuation law of shock wave pulse width and water depth in the shock wave stage, and does not conform to the actual situation. The method comprises the following steps: setting the working condition of underwater strong dynamic load, and determining the initial conditions required for calculation; calculating the underwater strong transient shock wave load based on the discontinuous Galerkin method in the spherically symmetric projection coordinate system, switching the underwater strong dynamic load calculation from the shock wave stage to the bubble stage, and simultaneously switching the calculation method of the shock wave load to a far-field shock wave propagation model solved by the discontinuous Galerkin method; solving the bubble equation by using the Runge-Kutta method to obtain the physical quantity of the underwater strong dynamic load, calculating the bubble load at a specified measuring point in water based on the potential flow theory, and calculating the full-sea-depth underwater strong transient shock wave and bubble load.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underwater strong dynamic load, and particularly relates to a calculation method suitable for underwater strong transient shock wave and bubble load in full sea depth. BACKGROUND

[0002] In recent years, rapid progress has been made in the field of deep sea exploration and deep sea development. In order to ensure the safety of deep sea submersibles and structures, the external load in the deep sea environment must be considered. As a kind of external load in the deep sea environment that can cause significant damage to submersibles and structures, underwater strong dynamic load is of great significance to accurately calculate it. At present, for underwater strong dynamic load, especially for strong dynamic load calculation in deep water environment, two kinds of calculation methods, numerical simulation and theoretical model, are generally used. For the calculation of underwater strong dynamic load in free field, the theoretical model requires less computing resources and shorter computing time than numerical simulation, so it is of great significance to innovate the theoretical model and improve the accuracy of the theoretical model calculation.

[0003] The theoretical model widely used for underwater strong dynamic load calculation at present is Geers-Hunter model, which divides underwater strong dynamic load into shock wave stage and bubble stage, uses double exponential empirical formula to calculate shock wave load in shock wave stage, and uses double asymptotic method to solve Hicks equation in bubble stage, which has acceptable accuracy in conventional underwater strong dynamic load working 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 decay law that the pulse width of the shock wave decreases with the increase of water depth, and the pulse width of the shock wave in 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 based on the double exponential empirical formula cannot ensure smooth connection with the pressure curve calculated according to the initial conditions of the bubble stage determined by the double exponential empirical formula, resulting in a pressure jump that does not match 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 the subsequent calculation, resulting in errors in the calculation of bubble load. SUMMARY

[0007] The present application is to solve the problems in the prior art that the double exponential empirical formula used in the shock wave stage of the Geers-Hunter model cannot reflect the attenuation law that the pulse width of the shock wave decreases with the increase of the 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 according to the initial conditions of the bubble stage determined based on the double exponential empirical formula, resulting in a pressure jump inconsistent with the actual physical situation; the initial conditions of the bubble stage determined based on the empirical formula will introduce errors into the subsequent calculation, resulting in errors in the calculation of the bubble load.

[0008] To solve the above technical problems, the present application is implemented by the following technical scheme:

[0009] The present application provides a calculation method suitable for full-sea depth underwater strong transient shock wave and bubble load, which comprises the following steps:

[0010] S1, setting the working condition of underwater strong dynamic load according to the need, for determining the initial conditions required for calculation;

[0011] S2, based on the initial conditions obtained in S1, calculating the underwater strong transient shock wave load in the spherical symmetry projection coordinate system based on the discontinuous Galerkin method, to obtain the shock wave load curve of the attenuation law;

[0012] S3, based on the shock wave load curve of the attenuation law obtained in S2, switching the calculation of underwater strong dynamic load from the shock wave stage to the bubble stage, and switching the calculation method of the shock wave load 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, solving the bubble equation of the same form by using the Runge-Kutta method, to obtain the physical quantities of the underwater strong dynamic load, including the radius R of the spherical bubble b , the first derivative of the radius with respect to time the second derivative of the radius with respect to time migration Z, migration velocity v, migration acceleration

[0014] S5, according to the physical quantities of the underwater strong dynamic load obtained in S4, calculating the bubble load at a specified measuring point in water based on the potential flow theory, to calculate the full-sea depth underwater strong transient shock wave and bubble load.

[0015] Further, a preferred embodiment is provided, wherein the working condition of the underwater strong dynamic load in S1 comprises overall arrangement, bubble parameters, and material parameters.

[0016] The general arrangement includes explosive mass W, transient reaction water depth h, measuring point horizontal coordinate x, measuring point vertical coordinate z, 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 force coefficient β, additional mass coefficient α, free surface reflection coefficient η.

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

[0019] Further, a preferred embodiment is provided, wherein S1 further comprises the steps of obtaining the radius R c of the spherical explosive in the shock wave stage according to the explosive mass W and the JWL equation of state parameter ρ0, obtaining the distance r = D of the measuring point in the spherical symmetry coordinate system according to the measuring point horizontal coordinate x and the measuring point vertical coordinate z in S1, and obtaining the initial pressure P g0 in the bubble according to the JWL equation of state parameter of the explosive in S1.

[0020] Further, a preferred embodiment is provided, wherein the method for obtaining the radius R c of the spherical explosive in the shock wave stage, the distance r = D of the measuring point in the spherical symmetry coordinate system, and the initial pressure P g0 in the bubble is as follows:

[0021]

[0022] Further, a preferred embodiment is provided, wherein the spherical symmetry projection coordinate system in S2 is a natural spherical symmetry coordinate system r with the center of the spherical explosive at r = 0, the position of the surface of the spherical bubble generated by the underwater transient reaction of the spherical explosive at r = R b is the coordinate λ = 0, and the position of the spherical shock wave surface generated by the underwater transient reaction of the spherical explosive at r = R s is the coordinate λ = 1.

[0023] Further, a preferred embodiment is provided, wherein the method for calculating the underwater strong transient shock wave load based on the discontinuous Galerkin method in the spherical symmetry projection coordinate system in S2 is as follows:

[0024]

[0025] wherein, is the derivative of the given physical quantity with respect to t when λ remains unchanged, which is expanded as

[0026] Furthermore, a preferred embodiment is provided, wherein the condition for switching the underwater strong dynamic load calculation from the shock wave stage to the bubble stage in S3 is: taking the center of the spherical explosive as the center, when the radius R of the spherical shock wave wave surface generated by its transient reaction is... s The radius R of the spherical bubble produced by the transient reaction at this moment is greater than that of the spherical bubble. b 10 times, that is, R s >10R b .

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

[0028]

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

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

[0031]

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

[0033] Furthermore, a preferred embodiment is provided, wherein the bubble load at a specified measuring point in the water is calculated based on potential flow theory in S5, and the method for calculating the strong transient shock wave and bubble load under full ocean depth is as follows:

[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 advantages of this invention are:

[0037] The method for calculating strong transient shock waves and bubble loads in full-ocean-depth underwater environments described in this invention solves for the shock wave load directly in a spherically symmetric projected coordinate system based on first principles, ensuring accurate results for the shock wave load and the correct attenuation law of the shock wave pulse width, thereby avoiding non-physical pressure jumps.

[0038] The calculation method for strong transient shock wave and bubble load suitable for full-sea-depth underwater is used for solving the shock wave load directly, and provides accurate initial conditions for the calculation of the bubble load, and can show higher accuracy than the commonly used Geers-Hunter model in the near-surface and deep sea.

[0039] The calculation method for strong transient shock wave and bubble load suitable for full-sea-depth underwater is used for solving the shock wave load directly, and provides accurate initial conditions for the calculation of the bubble load, and can show higher accuracy than the commonly used Geers-Hunter model in the near-surface and deep sea.

[0040] The calculation method for strong transient shock wave and bubble load suitable for full-sea-depth underwater is used for solving the shock wave load directly, and provides accurate initial conditions for the calculation of the bubble load, and can show higher accuracy than the commonly used Geers-Hunter model in the near-surface and deep sea. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 The flow chart of the calculation method for strong transient shock wave and bubble load suitable for full-sea-depth underwater is shown.

[0042] Figure 2 The flow chart of the calculation method for strong transient shock wave and bubble load suitable for full-sea-depth underwater is shown.

[0043] Figure 3 The comparison result schematic diagram of the load time history curve of 0.227 kg TNT at the measuring point at a distance of 0.69 m from the transient reaction at 182.88 m underwater is shown.

[0044] Figure 4 The comparison result schematic diagram of the bubble radius time history curve of 0.227 kg TNT formed by the transient reaction at 182.88 m underwater is shown.

[0045] Figure 5 The comparison result schematic diagram of the load time history curve of 0.453 kg TNT at the measuring point at a distance of 1285 m from the transient reaction at 1341 m underwater is shown.

[0046] Figure 6 The comparison result schematic diagram of the load time history curve of 0.453 kg TNT at the measuring point at a distance of 2169 m from the transient reaction at 2225 m underwater is shown.

[0047] Figure 7 The comparison result schematic diagram of the load time history curve of 0.453 kg TNT at the measuring point at a distance of 4241 m from the transient reaction at 4298 m underwater is shown.

[0048] Figure 8This is a schematic diagram showing the comparison results of the load-time history curves of 25.85 kg TNT at a transient response distance of 1285 meters underwater at a depth of 1341 meters, as described in an embodiment of the present invention.

[0049] Figure 9 This is a schematic diagram of the pulse width attenuation of the underwater strong transient shock wave according to an embodiment of the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them.

[0051] See Figures 1 to 9 This embodiment describes a calculation method applicable to strong transient shock waves and bubble loads in full-ocean-depth underwater environments. Based on underwater strong dynamic load conditions, this embodiment determines the initial conditions for calculation by providing the overall layout, bubble parameters, and material parameters. Starting from first principles, the shock wave load is directly calculated in a spherically symmetric projected coordinate system. After satisfying the conditions for switching from the shock wave stage to the bubble stage, the calculated results are used as the initial conditions for the bubble stage. Then, the Runge-Kutta method is used to solve the bubble equation with a unified form. Finally, the bubble load at the measuring point is obtained based on potential flow theory.

[0052] See Figure 1 As shown, a calculation method applicable to strong transient shock waves and bubble loads in full ocean depth includes the following steps:

[0053] S1. Set the working conditions of underwater strong dynamic load as needed to determine the initial conditions required for calculation;

[0054] S1 specifically includes the following steps:

[0055] S1.1 Determine the explosive mass W, transient reaction water depth h, x-coordinate of the measuring point, z-coordinate of the measuring point, and end time t. end Step size κ, delay time t ε Based on the overall layout, determine the dynamic viscosity μ, surface tension σ, and cavitation limit p. c The JWL equation of state parameters A, B, ω, R1, R2, ρ0, and E0 of the explosive are determined by using bubble parameters such as gravitational acceleration g, drag drag coefficient β, added mass coefficient α, and free surface reflection coefficient η.

[0056] S1.2 Based on the explosive mass W and the JWL equation of state parameter ρ0 of the explosive in S1.1, the radius R of the spherical explosive in the shock wave stage is obtained. c, the spherical symmetry coordinate system is obtained according to the measuring point horizontal coordinate x and the measuring point vertical coordinate z in S1.1, and the initial pressure P in the bubble is obtained according to the JWL state equation parameters of the explosive in S1.1 g0 , R c , D and P g0 The calculation method is as follows:

[0057]

[0058] S2, according to the initial conditions obtained in S1, the underwater strong transient shock wave load is calculated based on the discontinuous Galerkin method in the spherical symmetry projection coordinate system, the shock wave load curve with correct attenuation law is obtained, and accurate initial conditions are provided for the calculation of the bubble load;

[0059] The S2 specifically comprises the following steps:

[0060] S2.1, in the natural spherical symmetry coordinate system r with the center of the spherical explosive as the origin, the surface r=R b of the spherical bubble generated by the underwater transient reaction of the explosive is taken as λ=0, the spherical shock wave surface r=R s generated by the underwater transient reaction of the explosive is taken as λ=1, and the spherical symmetry projection coordinate system λ is established;

[0061] S2.2, on the basis of S2.1, the velocity u in the natural spherical symmetry coordinate system r, and the corresponding velocity U in the projection coordinate system λ are calculated as follows:

[0062]

[0063] S2.3, the Euler equation group to be solved by the discontinuous Galerkin method in the spherical symmetry projection coordinate system λ established in S2.2 is expressed in the following form:

[0064]

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

[0066] S2.4, in order to close the Euler equation group in S2.3, the Tamman state equation is used for the environmental flow field, and the JWL state equation is used for the gas in the bubble generated by the underwater transient reaction of the explosive, which are expressed in sequence as:

[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 x 10 8 Pa is the reference pressure;

[0070] S2.5, the pressure distribution condition in the natural spherical symmetry coordinate system r is:

[0071]

[0072] In the above formula: p l (λ, t) is the flow field pressure corresponding to the spherical symmetry projection coordinate system λ, ρ ∞ = 1000 kg / m 3 is the undisturbed flow field density;

[0073] S2.6, in order to establish the coordinate system in S2.1 and provide initial boundary conditions for the calculation of the shock wave load, considering that the shock wave propagation speed in water is much greater than the spherical bubble expansion speed, so that the shock wave propagates in water for the delay time t ε in S1.1, so that the shock wave wave surface r = R s is separated from the spherical bubble surface r = R b , and then the spherical symmetry projection coordinate system λ is established, at this time the spherical bubble radius R bε and the shock wave wave surface radius R sε are as follows:

[0074]

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

[0076] S2.7, the shock wave velocity in S2.6 is solved which needs to be obtained according to the Hugoniot condition, as follows:

[0077]

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

[0079]

[0080] S2.9, the fluid density in the Euler equation set described in S2.3 is as follows:

[0081]

[0082] S2.10, the boundary conditions required for solving the Euler equations in S2.3 are:

[0083]

[0084] S3, based on the shock wave results obtained in S2, when R s > 10R b , the underwater strong dynamic load is switched from the shock wave stage to the bubble stage, and the time satisfying the switching condition is taken as t = t e , 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;

[0085] S3 specifically includes the following steps:

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

[0087]

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

[0089]

[0090] S3.3, the actual sound speed C obtained in S3.2 is expanded at p = ρ ∞ gh, and let and δp = p - ρ ∞ gh, and ignore the obtained high-order small quantity o(δp) 2 , the simplified expression form of the actual sound speed C is 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, the calculation domain length L domain in the far-field shock wave propagation model is determined, and the left end point R f = R s -L domain of the calculation domain is obtained;

[0096] S3.6. Based on the left endpoint of the computational domain obtained in S3.5, a new spherically symmetric projective 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 from S3.4 into the spherically symmetric projected coordinate system χ established in S3.6, we can obtain the energy conservation equation as shown below:

[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 shown below:

[0103] F χ＝0 =F(R) f )F χ＝1 =F(R) s );

[0104] S4. Based on the initial conditions of the bubble load obtained in S2, the Runge-Kutta method is used to solve the bubble equation with a unified form, and the radius R of the spherical bubble formed by the underwater transient reaction of the explosive is obtained. b The derivative of the radius of the spherical bubble with respect to time Second derivative of radius with respect to time Migration Z, migration velocity v, migration acceleration Equal physical quantities;

[0105] S4 specifically includes the following steps:

[0106] S4.1. Based on the calculation results in S2, we can directly obtain the result at t = t e At time t, the initial internal pressure p of the bubble is used to solve the bubble equation with a unified form. b1 Initial bubble radius R b1 The calculation method is as follows:

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

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

[0109] S4.2, Derivative of spherical bubble radius 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 dissipation of the shock wave in the spherical symmetric projection coordinate system λ, and the recommended value is τ = 0.65;

[0112] S4.3, According to μ, σ determined in S1 and p obtained in S4.1 b1 , the initial pressure P of the bubble is determined 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 , v obtained as described in S4.2 and P obtained as described in S4.3 g1 are substituted into the bubble equation with a unified form as shown below, and the Runge-Kutta method is used for solving:

[0115]

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

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

[0118]

[0119] S5, According to each physical quantity obtained in S4, the bubble load at a specified measuring point in water is calculated based on the potential flow theory, and the bubble load at the measuring point r is obtained in the following manner:

[0120]

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

[0122] (1), Comparison of conventional underwater strong transient shock wave and bubble load

[0123] Figure 4The results of the comparison between the experimental data and the method and the Geers-Hunter model for the load at the measuring point 0.69 m away from the 0.227-kg TNT at 182.88 m underwater are given. It can be seen that, for the conventional underwater strong transient shock wave and the bubble load, the method and the Geers-Hunter model can be well fitted with the experimental results.

[0124] (2) Comparison of the bubble radius formed by the underwater transient reaction of explosives at a conventional water depth

[0125] Figure 5 The results of the comparison between the experimental data and the method and the Geers-Hunter model for the radius of the bubble generated by the transient reaction of 0.227-kg TNT at 182.88 m underwater are given. It can be seen that, for the radius change of the bubble formed by the underwater transient reaction of explosives at a conventional water depth, the method and the Geers-Hunter model can be well fitted with the experimental results.

[0126] (3) Comparison of the strong transient shock wave and the bubble load in deep water

[0127] Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 The results of the comparison between the experimental data and the method and the Geers-Hunter model for the strong transient shock wave and the bubble load in deep water under different working conditions are given. Among them, Figure 5 the working condition shown in FIG. 8 is the load at the measuring point 1285 m away from the transient reaction of 0.453-kg TNT at 1341 m underwater, Figure 6 the working condition shown in FIG. 9 is the load at the measuring point 2169 m away from the transient reaction of 0.453-kg TNT at 2225 m underwater, Figure 7 the working condition shown in FIG. 10 is the load at the measuring point 4241 m away from the transient reaction of 0.453-kg TNT at 4298 m underwater, Figure 8 and the working condition shown in FIG. 11 is the load at the measuring point 1285 m away from the transient reaction of 25.85-kg TNT at 1341 m underwater. It can be seen that the method can greatly improve the calculation accuracy of the underwater strong transient shock wave and the bubble load in deep water, give the correct trend of the shock wave pulse width with the change of water depth, and effectively reduce the non-physical jump of the load when the shock wave stage and the bubble stage are connected.

[0128] (4) Variation law of the strong transient shock wave pulse width with the water depth in deep water

[0129] Figure 9The variation law of the shock wave pulse width of TNT of different qualities obtained by the method under different water depths is given. It can be seen that the method can clearly show the law that the underwater strong transient shock wave pulse width decreases with the increase of the depth.

[0130] In summary, the embodiment discloses a calculation method suitable for underwater strong transient shock wave and bubble load in full sea depth. Firstly, the method sets the working condition of underwater strong dynamic load according to the need, so as to determine the initial condition required for calculation; secondly, the underwater strong transient shock wave load is calculated based on the discontinuous Galerkin method in the spherical symmetry coordinate system, the shock wave load curve with correct attenuation law is obtained, and accurate initial conditions are provided for the calculation of bubble load; then, the calculation of underwater strong dynamic 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 using the Runge-Kutta method, and the physical quantities such as the radius, expansion speed, expansion acceleration, migration, migration speed and migration acceleration of the spherical bubble formed by underwater transient reaction of explosives are obtained; finally, the bubble load at the specified measuring point in water is calculated based on the potential flow theory, so as to calculate the underwater strong transient shock wave and bubble load in full sea depth. The results calculated by the discontinuous Galerkin method in the spherical symmetry coordinate system provide more accurate shock wave load results for the underwater strong dynamic load in full sea depth, and provide more accurate initial conditions for the bubble stage, which ensures the smooth connection of the shock wave stage and the bubble stage, and also obtains more accurate bubble load results.

[0131] Those skilled in the art can understand that the above description is only preferred embodiments of the present application, and the features described in each embodiment and / or claim of the present disclosure can be combined or combined, even if such combination or combination is not explicitly described in the present disclosure. It is not intended to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, and those skilled in the art can modify the technical solutions described in the foregoing embodiments or make equivalent replacement of part of the technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0132] Although preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to include the preferred embodiments and all changes and modifications falling within the scope of the present application. Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application also intends to include these modifications and variations.

Claims

1. A method for calculating the underwater strong transient shock wave and bubble load suitable for all sea depths, characterized in that, The calculation method comprises the following steps: S1, setting a working condition of underwater strong dynamic load according to needs, for determining initial conditions required for calculation; S2, calculating the underwater strong transient shock wave load based on the discontinuous Galerkin method in a spherically symmetric projection coordinate system according to the initial conditions obtained in S1, to obtain a shock wave load curve of the decay law; S3, switching the underwater strong dynamic load calculation from the shock wave stage to the bubble stage based on the shock wave load curve of the decay law obtained in S2, and simultaneously switching the calculation method of the shock wave load to a far-field shock wave propagation model solved by the discontinuous Galerkin method; S4. Using the initial conditions of 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 strong dynamic load, including the radius R of the spherical bubble b , the derivative of the radius with respect to time the second derivative of the radius with respect to time migration Z, migration velocity v, migration acceleration S5, calculating the bubble load at a specified measuring point in water based on the physical quantity of the underwater strong dynamic load obtained in S4, to calculate the underwater strong transient shock wave and the bubble load in the whole sea depth.

2. The method for calculating the underwater strong transient shock wave and bubble load suitable for all sea depths according to claim 1, characterized in that, The working condition of the underwater strong dynamic load in S1 comprises overall arrangement, bubble parameters and material parameters. The overall arrangement includes the explosive mass W, the transient reaction water depth h, the measuring point horizontal coordinate x, the measuring point vertical coordinate z, and the end time t end , the step size K, and the delay time t ε ; Bubble parameters include dynamic viscosity μ, surface tension σ, cavitation limit p c , gravitational acceleration g, drag force coefficient β, added mass coefficient α, free surface reflection coefficient η; The material parameters are JWL state equation parameters A, B, ω, R1, R2, ρ0 and E0 of the used explosive.

3. The method for calculating the underwater strong transient shock wave and bubble load suitable for all sea depths according to claim 2, characterized in that, S1 also includes the step of obtaining the radius R of the spherical charge in the shock wave stage according to the mass W of the explosive and the JWL equation of state parameters ρ0 c , obtaining the distance r = D of the measuring point in the spherical coordinate system according to the horizontal coordinate x and the vertical coordinate z of the measuring point in S1, and obtaining the initial pressure P in the bubble according to the JWL equation of state parameters of the explosive in S1 g0 .

4. The method for calculating the underwater strong transient shock wave and bubble load suitable for all sea depths according to claim 3, characterized in that, The radius R of the spherical charge in the shock wave stage is obtained c , the distance r of the measuring point in the spherically symmetric coordinate system is D, and the initial pressure P in the bubble is g0 The method is as follows:

5. The method of claim 1, wherein, The spherical symmetry projection coordinate system described in S2 is a natural spherical symmetry coordinate system r with the center of the spherical explosive as r = 0, and the surface of the spherical bubble generated by the underwater transient reaction of the spherical explosive is r = R b The position of the spherical symmetry projection coordinate system described in S3 is the coordinate λ = 0, and the position of the spherical shock wave surface generated by the underwater transient reaction of the spherical explosive is r = R s The spherical symmetry projection coordinate system described in S4 is a spherical symmetry projection coordinate system with the coordinate λ = 1 6. The method of claim 1, wherein, The method for calculating the underwater strong transient shock wave load based on the discontinuous Galerkin method in the spherically symmetric projection coordinate system in S2 is: wherein is the derivative of the given physical quantity with respect to t when λ is held constant, which expands to 7. The method of claim 1, wherein, The condition for switching from the shock wave phase to the bubble phase in S3 is that the radius R of the spherical shock wave generated by the instantaneous reaction of the spherical explosive with the center of the spherical explosive as the center is greater than 10 times the radius R of the spherical bubble generated by the instantaneous reaction at this moment, that is, R s > 10R b . s b .​ 8. The method of claim 1, wherein, The far-field shock wave propagation model in S3 is: where L domain is the length of the domain, Y c = (γ - 1) / 2ρ ∞ C ∞ , γ = 7.15 is the ratio of specific heat of water, C is the sound speed in the flow field, where C ∞ = 1500 m / s is the sound speed in the undisturbed water medium, δp is the flow field disturbance pressure, is the shock wave propagation speed in the natural spherical symmetry coordinate system r.

9. The method of claim 1, wherein, The bubble equation in the same form in S4 is: In the formula, N is the enthalpy difference between the inner and outer surfaces of the bubble.

10. The method of claim 1, wherein, The method for calculating the bubble load at the specified measuring point in water based on the potential flow theory in S5 is: The value of the physical quantity at t is substituted into the above formula to obtain the bubble load at the measuring point.

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