Design method and system for regulating and controlling neutral collapse efficiency of underwater explosion bubbles

Abstract

The invention relates to the field of ship and maritime work structure protection, in particular to a regulation and control design method and system for underwater explosion bubble neutral collapse efficiency. Initial parameters of underwater explosion are input, and characteristic parameters of bubble pulsation are obtained according to an underwater explosion empirical formula; on the basis of bubble neutral collapse limiting conditions given by a potential flow theory, controllable parameters in underwater explosion application are adjusted; based on boundary condition limitation, a boundary integral matrix equation set containing a drainage basin interface is established; in combination with a dynamic boundary condition constructed by a Bernoulli equation, updating an interface position, and obtaining a motion state and a dynamic characteristic parameter of the bubble; the collapse efficiency of the bubbles is judged according to the momentum value of the bubbles in the last collapse stage, and controllable parameters of the bubbles are adjusted for calculation till a neutral collapse mode is achieved; and recording and post-processing the efficiency parameters of the neutral collapse of the underwater explosion bubbles. The method is used for solving the design problems of an underwater explosion bubble neutral collapse mode and a load in an existing project.

Description

Technical Field

[0001] The invention relates to the field of ship and marine structure protection, and is a design method and a system for regulating the neutral collapse efficiency of underwater explosion bubbles. Background Art

[0002] There are three types of collapse modes of large-scale bubbles generated by underwater explosions near underwater structures. Rigid boundaries attract bubbles to collapse toward the boundaries, free surfaces induce bubbles to collapse away from the boundaries, and when bubbles are subjected to opposite forces and equivalent forces, they no longer have an obvious tendency to move toward one side (neutral collapse). This is widely found in real underwater explosion applications, such as the downward repulsive force of the free surface on the bubbles and the upward buoyancy of the bubbles themselves offsetting each other, bubbles being attracted by structures on both sides, and internal bubbles being squeezed in the bubble array. The complex dynamic behavior of bubbles in the neutral collapse mode causes changes in their energy utilization and flow field loads. The neutral collapse of bubbles in the near field will increase the proportion of bubble jet energy, greatly reducing the damage of bubble pulsation and jet load to underwater structures, while the neutral collapse of bubbles in the far field will significantly enhance the pulsating load of bubbles, which can easily cause overall damage to underwater structures.

[0003] Since the physical mechanism of inducing neutral collapse of bubbles is relatively complex and the parameters involved are complicated, the previous understanding of this feature mostly remains at the qualitative level. Few studies can clearly give the parameter conditions for the occurrence of neutral collapse of bubbles and the induced flow field load characteristics for pulsating bubbles with obvious buoyancy effects, especially under combined boundary conditions. Determining the neutral collapse characteristics of bubbles under these conditions involves a lot of mechanistic research and parameter analysis. The boundary integral method converts the flow field information to the bubble and the boundary surface, thereby directly solving the interface motion information, which greatly saves the calculation time and cost. By solving the boundary integral equation and applying the dynamic boundary conditions constructed by the Bernoulli equation, the collapse characteristics of bubbles under different boundary conditions can be quickly solved. The Kelvin impulse law based on potential flow theory gives the momentum theoretical solution of the bubble at the end of the first cycle through analytical derivation, which can well characterize the bubble collapse characteristics. Combining the boundary integral method with the basic potential flow theory can realize the rapid prediction and regulation of the neutral collapse characteristics of bubbles, so as to be applied to the design of the neutral collapse efficiency of underwater explosion bubbles.

[0004] Most existing technologies predict the collapse efficiency of underwater explosion bubbles through direct numerical simulation. A large number of simulations are needed to obtain mechanistic laws to guide engineering practice. However, engineers have limited energy and cannot traverse all conditions, especially for the special bubble collapse feature of neutral bubble collapse, which requires high precision in control parameters and can easily lead to omission of working conditions. Summary of the invention

[0005] The invention provides a design method for regulating the neutral collapse efficiency of underwater explosion bubbles, which is used to solve the design problems of the neutral collapse mode and load of underwater explosion bubbles in existing projects.

[0006] The invention provides a system for regulating the neutral collapse efficiency of underwater explosion bubbles, which is used to realize a method for regulating the neutral collapse efficiency of underwater explosion bubbles.

[0007] The present invention is achieved through the following technical solutions:

[0008] A design method for regulating the neutral collapse efficiency of underwater explosion bubbles, the design method comprising the following steps:

[0009] Step 1: Input the initial parameters of underwater explosion and obtain the characteristic parameters of bubble pulsation according to the underwater explosion empirical formula;

[0010] Step 2: Based on the bubble neutral collapse restriction given by potential flow theory and the characteristic parameters obtained in step 1, the controllable parameters in the underwater explosion application are adjusted;

[0011] Step 3: Based on the parameters and boundary condition constraints adjusted in step 2, establish a boundary integral matrix equation group including the watershed interface;

[0012] Step 4: Based on the boundary integral matrix equation group including the flow domain interface in step 3 and the dynamic boundary conditions constructed by the Bernoulli equation, the interface position is updated to obtain the motion state and dynamic characteristic parameters of the bubble;

[0013] Step 5: Based on the motion state and dynamic characteristic parameters of step 4, the collapse efficiency of the bubble is determined according to the momentum value of the bubble at the end of collapse, and the controllable parameters of the bubble are adjusted for calculation until a neutral collapse mode is reached;

[0014] Step 6: Record and post-process the effectiveness parameters of the neutral collapse of underwater explosion bubbles.

[0015] Furthermore, the initial parameters of the underwater explosion in step 1 include the explosive equivalent, the water depth, and the distance between the explosive and the nearby structure, so as to set the initial state of the underwater explosion bubble;

[0016] After obtaining the initial state of the bubble, the characteristic parameters of the bubble, including the maximum radius and period of the bubble, can be calculated based on the empirical formula of underwater explosion;

[0017] The empirical formula for underwater explosion in step 1 is:

[0018]

[0019] Among them, R mis the maximum radius to which the underwater explosion bubble can expand, T is the bubble pulsation period, P ∞ is the hydrostatic pressure at the location of the bubble, w is the explosive equivalent, and h is the water depth where the explosive is located.

[0020] Furthermore, the step 2 adjusts the controllable parameters of the underwater explosion to satisfy the bubble neutral collapse restriction conditions given by the potential flow theory;

[0021] The limiting condition for the neutral collapse of underwater explosion bubbles near the water surface is:

[0022]

[0023] The neutral collapse constraint for underwater explosion bubbles above underwater structures is:

[0024]

[0025] Among them, d s is the distance between the bubble and the structure below it;

[0026] The neutral collapse constraint conditions of underwater explosion bubbles on the side of underwater structures are:

[0027]

[0028] The neutral collapse constraint condition for underwater explosion bubbles above structures near the water surface is:

[0029]

[0030] The neutral collapse constraint condition for underwater explosion bubbles on the side of the surface structure is:

[0031]

[0032] Among them, d w is the distance between the bubble and the side structure.

[0033] Furthermore, the neutral collapse restriction condition of underwater explosion bubbles on the side of underwater structures in shallow waters is:

[0034]

[0035] Among them, d e is the distance between the bubble and the seafloor.

[0036] Furthermore, in step 3, based on the boundary condition constraints of the underwater explosion bubble, the boundary integral equation is discretized to establish a solvable boundary integral matrix equation group; first, the matrix elements are calculated according to the following formula:

[0037]

[0038] Where i and j are natural numbers, ranging from 1 to n; G(i,j) is the Green function, G(i,j) = 1 / |r i -r j |, G ij and H ij are the elements of two n×n matrices respectively; s j represents all two-phase interfaces in the flow field, and λ(i) is the solid angle of the field point observing the flow field.

[0039] Furthermore, the matrix equation to be solved in step 4 is as follows:

[0040]

[0041] in, is the node velocity potential, is the normal derivative of the velocity potential.

[0042] The interface dynamic boundary condition constructed based on the Bernoulli equation is:

[0043]

[0044] Where P is the interface surface pressure;

[0045] The pressure P on the bubble surface can be calculated as follows:

[0046]

[0047] Among them, P0 is the initial internal pressure of the bubble, ε is the insulation coefficient, V0 and V are the bubble volumes at the initial moment and the current moment, respectively.

[0048] Furthermore, for the case of underwater structures, the normal velocity of the nodes on the boundary of the structure is zero, and the velocity potential can be obtained by solving the boundary integral equation. Therefore, for the case of explicitly discretizing the rigid boundary grid, the matrix equation needs to be transposed to separate the known physical quantities from the unknown physical quantities.

[0049] Furthermore, the normal velocity of the bubble surface and the velocity potential of the wall node are obtained at each time step by performing time advancement, and the tangential velocity of each node can be obtained based on the differential relationship between the velocity potential and the velocity; after the tangential velocity of the node is obtained, the interface position can be updated, and during the time advancement process, the time step is restricted;

[0050] The nodal position, velocity and pressure of the bubble at each time step are recorded, and the momentum of the bubble is calculated.

[0051] Furthermore, the step 5 determines the collapse efficiency of the bubble according to the momentum value of the bubble at the end of collapse. tIf it is not zero, you need to adjust the explosive equivalent or change the distance between the bubble and the structure appropriately and recalculate until the dimension F t Close to zero.

[0052] A system for regulating the neutral collapse efficiency of underwater explosion bubbles, the system using the design method for regulating the neutral collapse efficiency of underwater explosion bubbles as described above, the system comprising

[0053] The characteristic parameter acquisition module of the bubble pulsation inputs the initial parameters of the underwater explosion and obtains the characteristic parameters of the bubble pulsation according to the empirical formula of the underwater explosion;

[0054] The controllable parameter adjustment module adjusts the controllable parameters in the underwater explosion application based on the bubble neutral collapse restriction conditions given by the potential flow theory and the characteristic parameters obtained by the characteristic parameter acquisition module of the bubble pulsation;

[0055] An equation group establishment module establishes a boundary integral matrix equation group including a flow domain interface based on the parameters adjusted by the controllable parameter adjustment module and the boundary condition constraints;

[0056] The bubble motion state and dynamic characteristic parameter calculation module updates the interface position and obtains the bubble motion state and dynamic characteristic parameters based on the boundary integral matrix equation group including the flow domain interface suggested by the equation group establishment module and the dynamic boundary conditions constructed by the Bernoulli equation;

[0057] A neutral collapse mode calculation module, based on the motion state and dynamic characteristic parameters calculated by the motion state and dynamic characteristic parameter calculation module of the bubble, determines the collapse efficiency of the bubble according to the momentum value of the bubble at the end of collapse, and adjusts the controllable parameters of the bubble to calculate until the neutral collapse mode is reached;

[0058] The storage and post-processing module records and post-processes the effectiveness parameters of the neutral collapse of underwater explosion bubbles.

[0059] The beneficial effects of the present invention are:

[0060] The present invention combines the boundary integral method with the potential flow theory to establish a prediction and control method for the neutral collapse characteristics of underwater explosion bubbles.

[0061] The present invention can achieve the purpose of quickly predicting and designing the neutral collapse characteristics of underwater explosion bubbles under different conditions, and provides a theoretical basis and basic technical support for engineering construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 It is a flow chart of the method of the present invention.

[0063] Figure 2It is an illustration of the applicable range of the bubble neutral collapse restriction condition in the present invention, wherein the dotted line represents the critical line with an error of 5%.

[0064] Figure 3 It is an explanatory diagram of the time history change of bubble momentum in the neutral collapse mode of underwater explosion bubbles in the present invention.

[0065] Figure 4 It is an effect diagram of the water jet behavior generated by the neutral collapse of the underwater explosion bubble in the present invention, wherein the horizontal and vertical coordinates in the figure are dimensionless variables. DETAILED DESCRIPTION

[0066] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0067] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0068] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0069] The following is attached to this application specification Figure 1-4 , the technical solutions in the embodiments of the present application are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0070] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0071] Implementation Method 1

[0072] This embodiment provides a design method for regulating the neutral collapse efficiency of underwater explosion bubbles, the design method comprising the following steps:

[0073] Step 1: Input the initial parameters of underwater explosion and obtain the characteristic parameters of bubble pulsation according to the underwater explosion empirical formula;

[0074] Step 2: Based on the bubble neutral collapse restriction given by potential flow theory and the characteristic parameters obtained in step 1, the controllable parameters in the underwater explosion application are adjusted;

[0075] Step 3: Based on the parameters and boundary condition constraints adjusted in step 2, establish a boundary integral matrix equation group including the watershed interface;

[0076] Step 4: Based on the boundary integral matrix equation group including the flow domain interface in step 3 and the dynamic boundary conditions constructed by the Bernoulli equation, the interface position is updated to obtain the motion state and dynamic characteristic parameters of the bubble;

[0077] Step 5: Based on the motion state and dynamic characteristic parameters of step 4, the collapse efficiency of the bubble is determined according to the momentum value of the bubble at the end of collapse, and the controllable parameters of the bubble are adjusted for calculation until a neutral collapse mode is reached;

[0078] Step 6: Record and post-process the effectiveness parameters of the neutral collapse of underwater explosion bubbles.

[0079] Furthermore, the initial parameters of the underwater explosion in step 1 include explosive equivalent, water depth, and the distance between the explosive and nearby structures, etc. By modifying the above initial information parameters within a certain range, the initial state of the underwater explosion bubble can be set;

[0080] After obtaining the initial state of the bubble, the characteristic parameters of the bubble, including the maximum radius and period of the bubble, can be calculated based on the empirical formula of underwater explosion;

[0081] The empirical formula for underwater explosion in step 1 is:

[0082]

[0083] Among them, R m is the maximum radius to which the underwater explosion bubble can expand, T is the bubble pulsation period, P ∞ is the hydrostatic pressure at the location of the bubble, w is the explosive equivalent, and h is the water depth where the explosive is located.

[0084] Furthermore, the controllable parameters of the underwater explosion including the water depth, the distance from the structure, etc. are adjusted in step 2 so as to satisfy the bubble neutral collapse restriction conditions given by the potential flow theory;

[0085] In traditional engineering applications, it is generally believed that bubbles near the water surface collapse when they move away from the water surface, and the understanding of gravity effect and water surface influence is relatively weak. The quantitative relationship between water surface and gravity effect can be constructed by integrating the force time of the bubble in a whole cycle:

[0086]

[0087] Where F(t) is the difference between the equivalent force of the water surface and the buoyancy of the bubble, which is calculated based on the free collapse process of the vacuum bubble:

[0088]

[0089] Among them, d f is the distance between the bubble and the water surface, ρ is the density of water, g is the acceleration due to gravity, P ∞ is the hydrostatic pressure at the explosive location, R m The maximum radius to which an underwater explosion bubble can expand;

[0090] Solving the above equation according to the ideal vacuum bubble free collapse process, we can obtain the neutral collapse restriction condition of underwater explosion bubble near the water surface:

[0091]

[0092] Among them, d f is the distance between the bubble and the water surface, ρ is the density of water, g is the acceleration due to gravity, P ∞ is the hydrostatic pressure at the explosive location, R m The maximum radius to which an underwater explosion bubble can expand.

[0093] Furthermore, in step 2, for the underwater explosion bubbles above the underwater structure, theoretically, the force exerted by the underwater structure on the bubbles is in the same direction and magnitude as that on the water surface, so the neutral collapse constraint condition of the bubbles is:

[0094]

[0095] Among them, d s is the distance between the bubble and the structure below it. m is the maximum radius to which the underwater explosion bubble can expand, ρ is the density of water, g is the acceleration of gravity, P ∞ is the hydrostatic pressure at the explosive location;

[0096] The neutral collapse constraint conditions of underwater explosion bubbles on the side of underwater structures are:

[0097]

[0098] Among them, R mis the maximum radius to which the underwater explosion bubble can expand, ρ is the density of water, g is the acceleration of gravity, P ∞ is the hydrostatic pressure at the explosive location;

[0099] Furthermore, in step 2, for the underwater explosion bubble above the underwater structure near the water surface, the combined force of the water surface and the underwater structure on the bubble can be calculated as follows:

[0100]

[0101] According to the ideal vacuum bubble free collapse process, the neutral collapse constraint condition of underwater explosion bubble above the water structure near the water surface can be obtained by solving equation (3):

[0102]

[0103] Among them, R m is the maximum radius to which the underwater explosion bubble can expand, P ∞ is the hydrostatic pressure at the explosive location, d s is the distance between the bubble and the structure below it, d f is the distance between the bubble and the water surface, ρ is the density of water, and g is the acceleration due to gravity;

[0104] Further, in step 2, for the underwater explosion bubble on the side of the water surface structure, the combined force of the water surface and the underwater structure on the bubble can be calculated as follows:

[0105]

[0106] According to the ideal vacuum bubble free collapse process, the neutral collapse constraint condition of underwater explosion bubble near the water surface structure (explosive detonated on the side of the water surface structure) can be obtained by solving equation (3):

[0107]

[0108] Among them, d w is the distance between the bubble and the side structure; d s is the distance between the bubble and the structure below it; R m is the maximum radius to which the underwater explosion bubble can expand, ρ is the density of water, g is the acceleration of gravity, P ∞ is the hydrostatic pressure at the explosive location, d f is the distance between the bubble and the water surface;

[0109] Further, in step 2, the neutral collapse constraint condition of the underwater explosion bubble on the side of the underwater structure in shallow water is:

[0110]

[0111] Among them, d eis the distance between the bubble and the seafloor.

[0112] Furthermore, in step 3, based on the boundary condition constraints of the underwater explosion bubble, the boundary integral equation is discretized to establish a solvable boundary integral matrix equation group; first, the matrix elements are calculated according to the following formula:

[0113]

[0114] Where i and j are natural numbers ranging from 1 to n (n is the number of nodes on the interface); G(i,j) is the Green function, G(i,j) = 1 / |r i -r j |, G ij and H ij are the elements of two n×n matrices respectively; s j represents all two-phase interfaces in the flow field, and λ(i) is the solid angle of the field point observing the flow field.

[0115] Furthermore, the step 4 solves the constructed matrix equation and updates the interface position in combination with the dynamic boundary conditions; the matrix equation to be solved is as follows:

[0116]

[0117] in, is the node velocity potential, is the normal derivative of the velocity potential.

[0118] Furthermore, in step 4, the interface dynamic boundary condition constructed based on the Bernoulli equation is:

[0119]

[0120] Where P is the interface surface pressure;

[0121] Furthermore, in step 4, the pressure P on the bubble surface can be calculated as follows:

[0122]

[0123] Among them, P0 is the initial internal pressure of the bubble, ε is the insulation coefficient, V0 and V are the bubble volumes at the initial moment and the current moment, respectively.

[0124] Furthermore, for the case of underwater structures, the node normal velocity on the structure boundary is zero, and the velocity potential can be obtained by solving the boundary integral equation. Therefore, for the case of explicit discretization of rigid boundary grids, the matrix equation needs to be transposed to separate the known physical quantities from the unknown physical quantities. The specific formula is as follows:

[0125]

[0126] Among them, the following table b is the bubble surface node, and the following table w is the rigid wall surface node.

[0127] Furthermore, time advancement is performed to obtain the normal velocity of the bubble surface and the velocity potential of the wall nodes at each time step. The tangential velocity of each node can be obtained based on the differential relationship between the velocity potential and the velocity. After the tangential velocity of the node is obtained, the interface position can be updated. In the process of time advancement, in order to ensure the stability of the calculation, the time step needs to be restricted as follows:

[0128]

[0129] Among them, Δt is the time step, C0 is the empirical coefficient of the time step, which is taken as 0.03.

[0130] Furthermore, the node position, velocity and pressure of the bubble at each time step are recorded, and the momentum of the bubble is calculated as follows:

[0131]

[0132] Furthermore, the step 5 determines the collapse efficiency of the bubble according to the momentum value of the bubble at the end of collapse, such as Figure 2 As shown in Figure 2, the neutral collapse characteristics of the bubble calculated based on the initial parameters set by the theoretical solution have certain errors. Therefore, when the bubble is in a certain dimension F at the end of collapse, t If it is not zero, you need to adjust the explosive equivalent or change the distance between the bubble and the structure appropriately and recalculate until the dimension F t Close to zero, such as Figure 3 The bubble momentum is close to zero at the end of collapse. t The conditions close to zero are as follows:

[0133] |F t |≤0.05 (21)

[0134] Furthermore, in step 6, the performance parameters of the underwater explosion bubble when it reaches neutral collapse are recorded and post-processed, and the post-processing includes drawing a bubble morphology change diagram, a bubble jet velocity history curve, a bubble jet direction, and a load distribution, so as to achieve the regulation and design of the neutral collapse performance of the underwater explosion bubble, such as Figure 4 The figure shows the effect of bubble horizontal jet in neutral collapse mode.

[0135] like Figure 2As shown in the figure, in this calculation condition, the explosion bubble is located below the water surface and to the right of the side wall. The horizontal and vertical coordinates are dimensionless variables, the reference length is the maximum radius of the bubble, the reference density is the density of water, and the reference pressure is the hydrostatic pressure at the explosive position. The cloud map variable represents the error of the calculated neutral collapse of the bubble, that is, the absolute value of the momentum at the end of the bubble collapse. The black dotted line represents the contour line with an error of 0.03.

[0136] like Figure 3 As shown in the figure, in this calculation condition, the explosion bubble is located below the water surface and to the right of the side wall. Both the horizontal and vertical coordinates are dimensionless variables.

[0137] like Figure 4 As shown in the figure, in this calculation condition, the explosion bubble is located below the water surface and to the right of the side wall. The Z axis is vertically upward, and the Y axis is horizontally to the right. Both the horizontal and vertical coordinates are dimensionless variables.

[0138] It can be seen from the above that the implementation mode of the present invention will combine the boundary integral method and potential flow theory to establish a prediction and control method for the neutral collapse characteristics of underwater explosion bubbles, and use the analytical solution of potential flow theory to guide the parameter setting in the boundary integral simulation, so as to achieve the purpose of quickly predicting and designing the neutral collapse characteristics of underwater explosion bubbles under different conditions, and provide a theoretical basis and basic technical support for engineering construction.

[0139] Implementation Method 2

[0140] This embodiment provides a system for regulating the neutral collapse efficiency of underwater explosion bubbles. The system uses the design method for regulating the neutral collapse efficiency of underwater explosion bubbles as described in the first embodiment. The system includes

[0141] The characteristic parameter acquisition module of the bubble pulsation inputs the initial parameters of the underwater explosion and obtains the characteristic parameters of the bubble pulsation according to the empirical formula of the underwater explosion;

[0142] The controllable parameter adjustment module adjusts the controllable parameters in the underwater explosion application based on the bubble neutral collapse restriction conditions given by the potential flow theory and the characteristic parameters obtained by the characteristic parameter acquisition module of the bubble pulsation;

[0143] An equation group establishment module establishes a boundary integral matrix equation group including a flow domain interface based on the parameters adjusted by the controllable parameter adjustment module and the boundary condition constraints;

[0144] The bubble motion state and dynamic characteristic parameter calculation module updates the interface position and obtains the bubble motion state and dynamic characteristic parameters based on the boundary integral matrix equation group including the flow domain interface suggested by the equation group establishment module and the dynamic boundary conditions constructed by the Bernoulli equation;

[0145] A neutral collapse mode calculation module, based on the motion state and dynamic characteristic parameters calculated by the motion state and dynamic characteristic parameter calculation module of the bubble, determines the collapse efficiency of the bubble according to the momentum value of the bubble at the end of collapse, and adjusts the controllable parameters of the bubble to calculate until the neutral collapse mode is reached;

[0146] The storage and post-processing module records and post-processes the effectiveness parameters of the neutral collapse of underwater explosion bubbles.

[0147] The working principle of the characteristic parameter acquisition module of the bubble pulsation is that the initial parameters of the underwater explosion include the explosive equivalent, the water depth and the distance between the explosive and the nearby structure, etc. By modifying the above initial information parameters within a certain range, the initial state of the underwater explosion bubble can be set;

[0148] After obtaining the initial state of the bubble, the characteristic parameters of the bubble, including the maximum radius and period of the bubble, can be calculated based on the empirical formula of underwater explosion;

[0149] The empirical formula for underwater explosion is:

[0150]

[0151] Among them, R m is the maximum radius to which the underwater explosion bubble can expand, T is the bubble pulsation period, P ∞ is the hydrostatic pressure at the location of the bubble, w is the explosive equivalent, and h is the water depth where the explosive is located

[0152] The working principle of the controllable parameter adjustment module is to adjust the controllable parameters of the underwater explosion, including the water depth, the distance from the structure, etc., so that they meet the bubble neutral collapse restriction conditions given by the potential flow theory;

[0153] The neutral collapse restriction condition of underwater explosion bubbles near the water surface is:

[0154]

[0155] Among them, d f is the distance between the bubble and the water surface, ρ is the density of water, g is the acceleration due to gravity, P ∞ is the hydrostatic pressure at the explosive location, R m The maximum radius to which an underwater explosion bubble can expand;

[0156] The neutral collapse constraints of underwater explosion bubbles above underwater structures are:

[0157]

[0158] Among them, d s is the distance between the bubble and the structure below it. mis the maximum radius to which the underwater explosion bubble can expand, ρ is the density of water, g is the acceleration of gravity, P ∞ is the hydrostatic pressure at the explosive location;

[0159] The neutral collapse constraint conditions of underwater explosion bubbles on the side of underwater structures are:

[0160]

[0161] Among them, R m is the maximum radius to which the underwater explosion bubble can expand, ρ is the density of water, g is the acceleration of gravity, P ∞ is the hydrostatic pressure at the explosive location;

[0162] The neutral collapse constraint conditions of underwater explosion bubbles above the underwater structure near the water surface are:

[0163]

[0164] Among them, R m is the maximum radius to which the underwater explosion bubble can expand, P ∞ is the hydrostatic pressure at the explosive location, d s is the distance between the bubble and the structure below it, d f is the distance between the bubble and the water surface, ρ is the density of water, and g is the acceleration due to gravity;

[0165] The neutral collapse restriction conditions of underwater explosion bubbles near the surface structure (explosives are detonated on the side of the surface structure) are:

[0166]

[0167] Among them, d w is the distance between the bubble and the side structure; d s is the distance between the bubble and the structure below it; R m is the maximum radius to which the underwater explosion bubble can expand, ρ is the density of water, g is the acceleration of gravity, P ∞ is the hydrostatic pressure at the explosive location, d f is the distance between the bubble and the water surface;

[0168] The limiting conditions for neutral collapse of underwater explosion bubbles on the side of underwater structures in shallow waters are:

[0169]

[0170] Among them, d e is the distance between the bubble and the seafloor.

[0171] The working principle of the equation group establishment module is to discretize the boundary integral equation based on the boundary condition restriction of the underwater explosion bubble and establish a solvable boundary integral matrix equation group; firstly, the matrix elements are calculated according to the following formula:

[0172]

[0173] Where i and j are natural numbers ranging from 1 to n (n is the number of nodes on the interface); G(i,j) is the Green function, G(i,j) = 1 / |r i -r j |, G ij and H ij are the elements of two n×n matrices respectively; s j represents all two-phase interfaces in the flow field, and λ(i) is the solid angle of the field point observing the flow field.

[0174] The working principle of the bubble motion state and dynamic characteristic parameter calculation module is to solve the constructed matrix equation and update the interface position in combination with the dynamic boundary conditions; the matrix equation to be solved is as follows:

[0175]

[0176] in, is the node velocity potential, is the normal derivative of the velocity potential.

[0177] The interface dynamic boundary condition constructed based on the Bernoulli equation is:

[0178]

[0179] Where P is the interface surface pressure;

[0180] The pressure P on the bubble surface can be calculated as follows:

[0181]

[0182] Among them, P0 is the initial internal pressure of the bubble, ε is the insulation coefficient, V0 and V are the bubble volumes at the initial moment and the current moment, respectively.

[0183] Furthermore, for the case of underwater structures, the node normal velocity on the structure boundary is zero, and the velocity potential can be obtained by solving the boundary integral equation. Therefore, for the case of explicit discretization of rigid boundary grids, the matrix equation needs to be transposed to separate the known physical quantities from the unknown physical quantities. The specific formula is as follows:

[0184]

[0185] Among them, the following table b is the bubble surface node, and the following table w is the rigid wall surface node.

[0186] The normal velocity of the bubble surface and the velocity potential of the wall nodes are obtained by time advancement at each time step. The tangential velocity of each node can be obtained based on the differential relationship between the velocity potential and the velocity. After the tangential velocity of the node is obtained, the interface position can be updated. In the process of time advancement, in order to ensure the stability of the calculation, the time step needs to be restricted as follows:

[0187]

[0188] Among them, Δt is the time step, C0 is the empirical coefficient of the time step, which is taken as 0.03.

[0189] Furthermore, the node position, velocity and pressure of the bubble at each time step are recorded, and the momentum of the bubble is calculated as follows:

[0190]

[0191] The working principle of the neutral collapse mode calculation module is to judge the collapse efficiency of the bubble according to the momentum value of the bubble at the end of collapse. t If it is not zero, you need to adjust the explosive equivalent or change the distance between the bubble and the structure appropriately and recalculate until the dimension F t Close to zero. t The conditions close to zero are as follows:

[0192] |F t |≤0.05 (17)

[0193] The working principle of the storage and post-processing module is to record and post-process the performance parameters of the underwater explosion bubble when it reaches neutral collapse. The post-processing includes drawing a bubble morphology change diagram, a bubble jet velocity time history curve, a bubble jet direction, and a load distribution, so as to realize the regulation and design of the neutral collapse performance of the underwater explosion bubble.

[0194] It can be seen from the above that the implementation mode of the present invention will combine the boundary integral method and potential flow theory to establish a prediction and control method for the neutral collapse characteristics of underwater explosion bubbles, and use the analytical solution of potential flow theory to guide the parameter setting in the boundary integral simulation, so as to achieve the purpose of quickly predicting and designing the neutral collapse characteristics of underwater explosion bubbles under different conditions, and provide a theoretical basis and basic technical support for engineering construction.

[0195] Implementation Method 3

[0196] An embodiment of the present invention provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the memory is used to store software programs and modules, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory. The memory and the processor are connected via a bus. Specifically, the processor implements any step in the first embodiment above by running the computer program stored in the memory.

[0197] It should be understood that in the embodiments of the present invention, the processor may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0198] The memory may include a read-only memory, a flash memory, and a random access memory, and provides instructions and data to the processor. A part or all of the memory may also include a nonvolatile random access memory.

[0199] As can be seen from the above, the electronic device provided by the embodiment of the present invention can implement the design method for regulating the neutral collapse efficiency of underwater explosion bubbles as described in the first embodiment by running a computer program, and obtain a new end-to-end framework, called a group feature self-supervised model, for group behavior representation learning. The contextual relationship is captured by context-aware relationship prediction coding, which not only considers the spatial interaction contextual relationship, but also the overall scene time change contextual relationship, thereby obtaining a more comprehensive group behavior feature representation.

[0200] It should be understood that the above-mentioned integrated module / unit, if implemented in the form of a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on such an understanding, the present invention implements all or part of the processes in the above-mentioned implementation method, and can also be completed by instructing the relevant hardware through a computer program. The above-mentioned computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method implementations when executed by the processor. Among them, the above-mentioned computer program includes computer program code, and the above-mentioned computer program code can be in source code form, object code form, executable file or some intermediate form. The above-mentioned computer-readable medium may include: any entity or device capable of carrying the above-mentioned computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the above-mentioned computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction.

[0201] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest range consistent with the principles and novel features disclosed herein.

[0202] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the above-mentioned device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the implementation method can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method implementation method, which will not be repeated here.

[0203] It should be noted that the methods and detailed examples provided in the above embodiments can be combined with the devices and equipment provided in the embodiments, and references can be made to each other, and no further details will be given.

[0204] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0205] In the embodiments provided by the present invention, it should be understood that the disclosed device / terminal equipment and method can be implemented in other ways. For example, the device / equipment implementation described above is only illustrative, for example, the division of the above modules or units is only a logical function division, and in actual implementation, another division method can be used, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0206] The above-mentioned embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above-mentioned embodiments, or replace some of the technical features therein by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A design method for regulating the neutral collapse efficiency of underwater explosion bubbles, characterized in that: The design method comprises the following steps: Step 1: Input the initial parameters of underwater explosion and obtain the characteristic parameters of bubble pulsation according to the underwater explosion empirical formula; Step 2: Based on the bubble neutral collapse restriction given by potential flow theory and the characteristic parameters obtained in step 1, the controllable parameters in the underwater explosion application are adjusted; Step 3: Based on the parameters and boundary condition constraints adjusted in step 2, establish a boundary integral matrix equation group including the watershed interface; Step 4: Based on the boundary integral matrix equation group including the flow domain interface in step 3 and the dynamic boundary conditions constructed by the Bernoulli equation, the interface position is updated to obtain the motion state and dynamic characteristic parameters of the bubble; Step 5: Based on the motion state and dynamic characteristic parameters of step 4, the collapse efficiency of the bubble is determined according to the momentum value of the bubble at the end of collapse, and the controllable parameters of the bubble are adjusted for calculation until a neutral collapse mode is reached; Step 6: Record and post-process the effectiveness parameters of the neutral collapse of underwater explosion bubbles.

2. The design method according to claim 1, characterized in that: The initial parameters of the underwater explosion in step 1 include the explosive equivalent, the water depth and the distance between the explosive and the nearby structure, which can set the initial state of the underwater explosion bubble; After obtaining the initial state of the bubble, the characteristic parameters of the bubble, including the maximum radius and period of the bubble, can be calculated based on the empirical formula of underwater explosion; The empirical formula for underwater explosion in step 1 is: Among them, R m is the maximum radius to which the underwater explosion bubble can expand, T is the bubble pulsation period, P ∞ is the hydrostatic pressure at the location of the bubble, w is the explosive equivalent, and h is the water depth where the explosive is located.

3. The design method according to claim 1, characterized in that: The step 2 adjusts the controllable parameters of the underwater explosion to satisfy the bubble neutral collapse restriction conditions given by the potential flow theory; The neutral collapse restriction condition of underwater explosion bubbles near the water surface is: Among them, d f is the distance between the bubble and the water surface, ρ is the density of water, g is the acceleration due to gravity, P ∞ is the hydrostatic pressure at the explosive location, R m The maximum radius to which an underwater explosion bubble can expand; The neutral collapse constraints of underwater explosion bubbles above underwater structures are: Among them, d s is the distance between the bubble and the structure below it; The neutral collapse constraint conditions of underwater explosion bubbles on the side of underwater structures are: The neutral collapse constraint conditions of underwater explosion bubbles above the underwater structure near the water surface are: The neutral collapse restriction condition of underwater explosion bubbles near the surface structure is: Among them, d w is the distance between the bubble and the side structure.

4. The design method according to claim 3, characterized in that: The limiting conditions for neutral collapse of underwater explosion bubbles on the side of underwater structures in shallow waters are: Among them, d e is the distance between the bubble and the seafloor.

5. The design method according to claim 4, characterized in that: In step 3, based on the boundary condition restriction of the underwater explosion bubble, the boundary integral equation is discretized to establish a solvable boundary integral matrix equation group; first, the matrix elements are calculated according to the following formula: Where i and j are natural numbers, ranging from 1 to n; G(i,j) is the Green function, G(i,j) = 1 / |r i -r j |, G ij and H ij are the elements of two n×n matrices respectively; s j represents all two-phase interfaces in the flow field, and λ(i) is the solid angle of the field point observing the flow field.

6. The design method according to claim 5, characterized in that: The matrix equation to be solved in step 4 is as follows: in, is the node velocity potential, is the normal derivative of the velocity potential. The interface dynamic boundary condition constructed based on the Bernoulli equation is: Where P is the interface surface pressure; The pressure P on the bubble surface can be calculated as follows: Among them, P0 is the initial internal pressure of the bubble, ε is the insulation coefficient, V0 and V are the bubble volumes at the initial moment and the current moment, respectively.

7. The design method according to claim 6, characterized in that: For the case of underwater structures, the node normal velocity on the boundary of the structure is zero, and the velocity potential can be obtained by solving the boundary integral equation. Therefore, for the case of discretizing the rigid boundary grid, the matrix equation needs to be shifted to separate the known physical quantities from the unknown physical quantities.

8. The design method according to claim 6, characterized in that: The normal velocity of the bubble surface and the velocity potential of the wall node are obtained by time advancement at each time step. The tangential velocity of each node can be further obtained based on the differential relationship between the velocity potential and the velocity. After the tangential velocity of the node is obtained, the interface position can be updated. During the time advancement process, the time step is restricted. The nodal position, velocity and pressure of the bubble at each time step are recorded, and the momentum of the bubble is calculated.

9. The design method according to claim 1, characterized in that: The step 5 determines the collapse efficiency of the bubble according to the momentum value of the bubble at the end of collapse. t If it is not zero, you need to adjust the explosive equivalent or change the distance between the bubble and the structure appropriately and recalculate until the dimension F t Close to zero.

10. A neutral collapse efficiency control system for underwater explosion bubbles, characterized in that: The system uses the design method for regulating the neutral collapse efficiency of underwater explosion bubbles as described in any one of claims 1 to 9, and the system includes The characteristic parameter acquisition module of the bubble pulsation inputs the initial parameters of the underwater explosion and obtains the characteristic parameters of the bubble pulsation according to the empirical formula of the underwater explosion; The controllable parameter adjustment module adjusts the controllable parameters in the underwater explosion application based on the bubble neutral collapse restriction conditions given by the potential flow theory and the characteristic parameters obtained by the characteristic parameter acquisition module of the bubble pulsation; An equation group establishment module establishes a boundary integral matrix equation group including a flow domain interface based on the parameters adjusted by the controllable parameter adjustment module and the boundary condition constraints; The bubble motion state and dynamic characteristic parameter calculation module updates the interface position and obtains the bubble motion state and dynamic characteristic parameters based on the boundary integral matrix equation group including the flow domain interface suggested by the equation group establishment module and the dynamic boundary conditions constructed by the Bernoulli equation; A neutral collapse mode calculation module, based on the motion state and dynamic characteristic parameters calculated by the motion state and dynamic characteristic parameter calculation module of the bubble, determines the collapse efficiency of the bubble according to the momentum value of the bubble at the end of collapse, and adjusts the controllable parameters of the bubble to calculate until the neutral collapse mode is reached; The storage and post-processing module records and post-processes the effectiveness parameters of the neutral collapse of underwater explosion bubbles.

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