Ship gas explosion damage assessment method based on gas-solid coupling model

Abstract

The invention provides a ship gas explosion damage assessment method based on a gas-solid coupling model. The method comprises the following steps: constructing a gas explosion numerical calculation model based on a computational fluid mechanics theory, and calculating to obtain the pressure of gas explosion on a ship body; in order to evaluate the damage of the gas explosion to the ship structure, the reflection pressure borne by the ship body is calculated; and based on a near-field dynamics method, constructing a ship damage evaluation numerical calculation model, and evaluating the damage caused by gas explosion to the ship body. According to the method, the fluid dynamic behavior of gas explosion is accurately simulated by utilizing a compressible fluid mechanics theory, the dynamic response of the ship structure is simulated in combination with a near-field dynamics method, and the damage condition of the ship structure under explosion impact can be rapidly and accurately evaluated in a ship gas explosion scene; through combination of related test data and a calculation result of the model, powerful support is provided for ship safety design and accident prevention.

Description

Technical Field

[0001] The present invention relates to the technical field of ship gas explosion damage assessment, and in particular to a ship gas explosion damage assessment method based on a gas-solid coupling model. Background Art

[0002] Damage assessment for ship gas explosions is crucial for ship safety design and accident prevention. Gas leaks or external explosions can trigger explosions while a ship is underway or at anchor, leading to serious structural damage and accidents. Diesel gas, in particular, is flammable and explosive, potentially causing explosions in the ship's environment, posing a serious threat to the ship's structure and personnel safety.

[0003] Ship gas explosions involve complex gas-solid coupling effects, and the dynamic effects of the explosion shock wave on the ship's structure require precise simulation. The dynamic interaction between the high-pressure gas generated by the explosion and the ship's structure requires precise simulation, while post-explosion damage assessments require rapid and accurate results to support emergency response and repair decisions. Furthermore, actual explosion scenarios may involve complex situations such as multiple explosion sources and irregular explosion shapes, requiring flexible simulation and assessment. Because ship gas explosions are a complex multi-physics problem involving the dynamic interaction between the gas explosion shock and the ship's structure, this gas-solid coupling effect makes damage assessments on ship structures highly complex. Summary of the Invention

[0004] To address the aforementioned technical issues, a method for assessing damage from ship gas explosions based on a gas-solid coupling model is provided. By coupling a gas explosion model with a ship structure model using peridynamic methods, the present invention accurately simulates the dynamic effects of a gas explosion on a ship structure and rapidly assesses the damage to the ship structure.

[0005] The technical means adopted in the present invention are as follows:

[0006] A method for assessing ship gas explosion damage based on a gas-solid coupling model includes:

[0007] S1. Based on computational fluid dynamics theory, a numerical solution model for gas explosion is constructed to calculate the pressure of gas explosion on the hull;

[0008] S2. To evaluate the damage to the ship structure caused by the gas explosion, calculate the reflected pressure on the hull;

[0009] S3. Based on the peridynamics method, a numerical solution model for ship damage assessment is constructed to evaluate the damage caused by gas explosion to the hull.

[0010] Furthermore, step S1 specifically includes:

[0011] S11. Obtain input parameters, including density, volume fraction, specific internal energy, and specific heat ratio of gas within a preset range, and discretize the explosion area into a finite unit grid based on the finite volume method;

[0012] S12, calculating the initial explosion pressure of the explosion point grid by solving the conservation equation and combining the state equation;

[0013] S13, using a flux calculation method to evaluate the flux at the interface between the explosion point grid and the adjacent grids, which is used to update the conserved variables and obtain the flow field state at the next time step;

[0014] S14. Calculate the pressure of adjacent grids through the state equation according to the updated conserved variables;

[0015] S15. Through the gradual iteration of time steps, the process of gas explosion pressure being transmitted to the hull is finally simulated.

[0016] Furthermore, step S12 specifically includes:

[0017] S121. Calculate the density ρ0 of the mixed gas z using the following formula:

[0018] ρ0=α1ρ1+α2ρ2

[0019] Where ρ1 represents the density of diesel volatile gas x; ρ2 represents the density of air y;

[0020] S122. Calculate the specific internal energy e0 of the mixed gas z using the following formula:

[0021]

[0022] Where, e1 represents the specific internal energy of diesel volatilized gas x, and e2 represents the specific internal energy of air y;

[0023] S123. Based on the calculated density ρ0 of the mixed gas z and the specific internal energy e0 of the mixed gas z, and in accordance with computational fluid dynamics theory, calculate the pressure generated by the mixed gas z of the diesel volatile gas x and air y at the initial explosion time t0 in the explosion point grid. The calculation formula is as follows:

[0024]

[0025] Where p0 represents the pressure generated by the explosion of the mixed gas z; α1 represents the volume fraction of the diesel volatile gas x, and α2 represents the volume fraction of the air y. For a mixed gas composed only of these two gases, α1+α2=1; ξ1 represents the parameter related to the diesel volatile gas x; ξ2 represents the parameter related to the air y. Γ irepresents the Grüneisen parameter of the i-th phase; Π1 and Π2 represent functions related to the state equation;

[0026] S124. Calculate the specific heat ratio γ0 of the mixed gas z using the following formula:

[0027]

[0028] Among them, c p1 represents the constant pressure specific heat capacity of diesel volatile gas x; c p2 represents the constant pressure specific heat capacity of air y; c v1 represents the constant volume specific heat capacity of diesel volatile gas x; c v2 represents the specific heat capacity at constant volume of air y;

[0029] S125, diesel volatile gas x, air y and mixed gas z are all regarded as ideal gases. According to the ideal gas state equation in computational fluid dynamics theory, for ideal gas, Γ i =γ i , Π i =0, calculate the pressure of the mixed gas z at the initial explosion moment, the calculation formula is as follows:

[0030] p0=(γ0-1)ρ0e0.

[0031] Furthermore, step S13 specifically includes:

[0032] S131. Calculate the wave velocity S of the explosion grid own , the calculation formula is as follows:

[0033]

[0034] Among them, N own =u own *n own , represents the normal velocity component of the explosion grid, u own represents the mixing velocity of the gas in the explosion grid, n own Represents the surface normal vector of the explosion mesh; represents the speed of sound in the explosion grid, p own represents the pressure of the gas in the explosion grid, γ own represents the specific heat ratio of the gas in the explosion grid, ρ own Indicates the density of the gas in the explosion grid; represents the normal weighted average velocity component between the two explosion grids, represents the weighted average sound speed among explosion grids;

[0035] S132. Calculate the wave speed S of adjacent grids nei , the calculation formula is as follows:

[0036]

[0037] Among them, N nei =u nei *n nei , represents the normal velocity component of the adjacent grid, u nei Indicates the mixing velocity of gases in adjacent grids, n nei Represents the surface normal vector of the adjacent mesh; represents the sound speed of the adjacent grid, p nei represents the pressure of the gas in the adjacent grid, γ nei represents the specific heat ratio of gases in adjacent grids, ρ nei Represents the density of gas in adjacent grids; represents the normal weighted average velocity component between two adjacent grids, represents the weighted average sound speed between adjacent grids;

[0038] S133. Use the HLL method to calculate the flux between the explosion grid and the adjacent grids. The calculation formula is as follows:

[0039]

[0040] Among them, S own Indicates the wave speed of the explosion grid; S nei represents the wave velocity of the adjacent grid; F own represents the flux of the explosion grid; F nei represents the flux of adjacent grids; U own Represents the conserved quantity of the explosion grid; U nei represents the conserved quantity of adjacent grids;

[0041] S134. Calculate the conservation quantity U between the explosion grid and the adjacent grids in the current time step. The calculation formula is as follows:

[0042]

[0043] Where ρ represents the mixed density of the gas in the explosion grid and the adjacent grids at the current time step; E represents the total energy of the gas in the explosion grid and the adjacent grids at the current time step;

[0044] S135. Calculate the flux F between the explosion grid and the adjacent grids at the current time step. The calculation formula is as follows:

[0045]

[0046] Where I represents the identity matrix of the explosion grid and the adjacent grids at the current time step;

[0047] S136, flux is used to update the conservation quantity. According to the first-order Euler time integration method in computational fluid dynamics theory, the conservation quantity U of the next time step is calculated. n+1 , the calculation formula is as follows:

[0048]

[0049] Among them, U n Represents the conserved quantity of the current time step; Δt represents the time step; represents the flux divergence at the current time step, and ΔV represents the volume of the grid.

[0050] Furthermore, step S14 specifically includes:

[0051] S141. During the numerical simulation of gas explosion using compressible computational fluid dynamics theory, since the density, volume fraction, specific internal energy, and specific heat ratio of various gases in the initial state (t=0) are known, the initial explosion pressure is calculated using the formula in step S125.

[0052] S142: Since the gas velocity of the explosion grid in the initial state is known, and the adjacent grid is not affected by the explosion, the weighted average velocity between the two grids is calculated. The sound velocity of the current grid can be obtained by the specific heat ratio and density of the gas and the initial explosion pressure. The weighted average sound velocity between the two grids is then calculated, and the grid interface flux is then calculated using the formula in step S133.

[0053] S143. After obtaining the flux between the grid interfaces, calculate the flux divergence Then, the first-order Euler time integration method in the formula of step S136 is used to update the conserved quantity U;

[0054] S144, the conserved quantity U includes the density, volume fraction, mixing velocity, and total energy parameters of various gases, and then the explosion pressure and interface flux at the next time step are calculated based on the new conserved quantity;

[0055] S145, continue to iterate to obtain the explosion pressure at each time step until the preset time step is reached. The calculated explosion pressure F e That is the pressure of the gas explosion on the hull.

[0056] Furthermore, step S2 specifically includes:

[0057] S21. For an ideal gas, under normal reflection, the incident overpressure is calculated using the following formula:

[0058]

[0059] in, represents the Mach number of the shock wave, S represents the speed of the shock wave, c represents the speed of sound; γ represents the specific heat ratio; p a Indicates environmental pressure;

[0060] S22. Based on the calculated incident overpressure, calculate the reflected overpressure using the following formula:

[0061]

[0062] Where Δp f Indicates reflected overpressure;

[0063] S23. Based on the calculated reflected overpressure, calculate the reflected pressure on the hull using the following formula:

[0064] F s =Δp f *A

[0065] Where A represents the unit area.

[0066] Furthermore, step S3 specifically includes:

[0067] S31. Obtain input parameters, including hull geometry, hull density, and pressure generated by gas explosion within a preset range;

[0068] S32, discretizing the hull into a certain number of hull structural units with finite volume and finite mass, and discretizing the hull within a preset range into hull structural units before performing calculations;

[0069] S33, calculating and determining the neighborhood of each hull structural unit and other hull structural units within the neighborhood;

[0070] S34, calculating various forces of the hull structural units that are not in direct contact with the explosion fluid and the explosion wave at the current time step;

[0071] S35. Based on the principles of peridynamics and Newton's second law, the movement of the hull structure unit s in direct contact with the explosion fluid and explosion wave at the current time step t is calculated as follows:

[0072]

[0073] Among them, ρ s represents the density of structural unit s; represents the acceleration of the structural unit s;

[0074] S36. In the next time step after the initial state, the quantities of the hull structural units that are not in direct contact with the explosion fluid and the explosion wave are obtained on the right side of the formula in step S35, and the density ρ of all hull structural units is sIt is known that the acceleration of the hull structural unit that is not in direct contact with the explosion fluid and the explosion wave can be directly calculated by the formula in step S35. Then calculate their speed Displacement and spatial position vector

[0075] S37. Calculate the bond elongation s of all structural units and other structural units in their neighborhood at the current time step, and use the function μ used to characterize whether the bond is broken to obtain the bond breaking condition. The specific formula is as follows:

[0076]

[0077] Among them, s c represents the critical elongation of the bond;

[0078] S38, outputting the position, displacement, velocity and bond fracture status of each hull structural unit in the current time step to perform hull damage assessment of gas explosion;

[0079] S39. Check whether the preset time step is reached. If so, terminate the calculation. If not, repeat steps S34 to S38.

[0080] Furthermore, step S35 specifically includes:

[0081] S351. Calculate the resultant force of the peridynamic bond forces of other structural units on the structural unit s in its neighborhood N. The calculation formula is as follows:

[0082]

[0083] in, represents the resultant force of the peridynamic bond forces of other structural units on the structural unit s in its neighborhood N; represents the relative spatial position vector of the structural unit s relative to other structural units s′ in its neighborhood N, represents the spatial position vector of the structural unit s′, represents the spatial position vector of the structural unit s, Represents the relative displacement vector of the structural unit s to other structural units s′ in its neighborhood N, represents the displacement of the structural unit s, represents the displacement of the structural unit s′;

[0084] In the above formula, It is expressed by the following formula:

[0085]

[0086] in, represents the microscopic bond function, γ represents the radius of the neighborhood N, s represents the bond elongation, μ is used to characterize whether the bond is broken, and s c represents the critical elongation of the bond;

[0087] S352. Calculate the gas explosion and pressure on the structural unit s The calculation formula is as follows:

[0088]

[0089] For the hull particles that are not in direct contact with the explosion fluid and explosion wave, this part of the force is 0;

[0090] S353. Obtain the volume force on the structural unit s is a known item.

[0091] Compared with the prior art, the present invention has the following advantages:

[0092] 1. The present invention provides a ship gas explosion damage assessment method based on a gas-solid coupling model. It uses compressible fluid mechanics theory to accurately simulate the fluid dynamics behavior of gas explosions, and combines it with peri-field dynamics methods to simulate the dynamic response of ship structures. In the scenario of a ship gas explosion, it can quickly and accurately assess the damage to the ship structure under the impact of the explosion. Combined with relevant test data and the calculation results of this model, it provides strong support for ship safety design and accident prevention.

[0093] 2. The present invention provides a ship gas explosion damage assessment method based on a gas-solid coupling model. Through high-precision numerical simulation, it can significantly reduce dependence on large-scale physical experiments, effectively reducing R&D costs and project economic expenses while ensuring the reliability of the assessment.

[0094] Based on the above reasons, the present invention can be widely promoted in the fields of ship gas explosion damage assessment and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0096] Figure 1 This is a flow chart of the numerical solution model of gas explosion based on computational fluid dynamics theory of the present invention.

[0097] Figure 2This is a flow chart of the numerical solution model for ship damage assessment based on the peridynamics method of the present invention.

[0098] Figure 3 A flow chart of ship gas explosion damage assessment using the method of the present invention is provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0099] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0100] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0101] The present invention provides a method for assessing damage caused by ship gas explosion based on a gas-solid coupling model, comprising:

[0102] S1. Based on computational fluid dynamics theory, a numerical solution model for gas explosion is constructed to calculate the pressure of gas explosion on the hull;

[0103] S2. To evaluate the damage to the ship structure caused by the gas explosion, calculate the reflected pressure on the hull;

[0104] S3. Based on the peridynamics method, a numerical solution model for ship damage assessment is constructed to evaluate the damage caused by gas explosion to the hull.

[0105] When specifically implemented, as a preferred embodiment of the present invention, Figure 1 As shown, step S1 specifically includes:

[0106] S11. Obtain input parameters, including density, volume fraction, specific internal energy, and specific heat ratio of gas within a preset range, and discretize the explosion area into a finite unit grid based on the finite volume method;

[0107] S12, calculating the initial explosion pressure of the explosion point grid by solving the conservation equation and combining the state equation;

[0108] S13, using a flux calculation method to evaluate the flux at the interface between the explosion point grid and the adjacent grids, which is used to update the conserved variables and obtain the flow field state at the next time step;

[0109] S14. Calculate the pressure of adjacent grids through the state equation according to the updated conserved variables;

[0110] S15. Through the gradual iteration of time steps, the process of gas explosion pressure being transmitted to the hull is finally simulated.

[0111] In specific implementation, as a preferred embodiment of the present invention, step S12 specifically includes:

[0112] S121. Calculate the density ρ0 of the mixed gas z using the following formula:

[0113] ρ0=α1ρ1+α2ρ2

[0114] Where ρ1 represents the density of diesel volatile gas x; ρ2 represents the density of air y;

[0115] S122. Calculate the specific internal energy e0 of the mixed gas z using the following formula:

[0116]

[0117] Where, e1 represents the specific internal energy of diesel volatilized gas x, and e2 represents the specific internal energy of air y;

[0118] S123. Based on the calculated density ρ0 of the mixed gas z and the specific internal energy e0 of the mixed gas z, and in accordance with computational fluid dynamics theory, calculate the pressure generated by the mixed gas z of the diesel volatile gas x and air y at the initial explosion time t0 in the explosion point grid. The calculation formula is as follows:

[0119]

[0120] Where p0 represents the pressure generated by the explosion of the mixed gas z; α1 represents the volume fraction of the diesel volatile gas x, and α2 represents the volume fraction of the air y. For a mixed gas composed only of these two gases, α1+α2=1; ξ1 represents the parameter related to the diesel volatile gas x; ξ2 represents the parameter related to the air y. Γ i represents the Grüneisen parameter of the i-th phase; Π1 and Π2 represent functions related to the state equation;

[0121] S124. Calculate the specific heat ratio γ0 of the mixed gas z using the following formula:

[0122]

[0123] Among them, c p1 represents the constant pressure specific heat capacity of diesel volatile gas x; c p2 represents the constant pressure specific heat capacity of air y; c v1 represents the constant volume specific heat capacity of diesel volatile gas x; c v2 represents the specific heat capacity at constant volume of air y;

[0124] S125, diesel volatile gas x, air y and mixed gas z are all regarded as ideal gases. According to the ideal gas state equation in computational fluid dynamics theory, for ideal gas, Γ i =γ i , Π i =0, calculate the pressure of the mixed gas z at the initial explosion moment, the calculation formula is as follows:

[0125] p0=(γ0-1)ρ0e0.

[0126] In specific implementation, as a preferred embodiment of the present invention, step S13 specifically includes:

[0127] S131. Calculate the wave velocity S of the explosion grid own , the calculation formula is as follows:

[0128]

[0129] Among them, N own =u own *n own , represents the normal velocity component of the explosion grid, u own represents the mixing velocity of the gas in the explosion grid, n own Represents the surface normal vector of the explosion mesh; represents the speed of sound in the explosion grid, p own represents the pressure of the gas in the explosion grid, γ own represents the specific heat ratio of the gas in the explosion grid, ρ own Indicates the density of the gas in the explosion grid; represents the normal weighted average velocity component between the two explosion grids, represents the weighted average sound speed among explosion grids;

[0130] S132. Calculate the wave speed S of adjacent grids nei , the calculation formula is as follows:

[0131]

[0132] Among them, N nei =u nei *n nei , represents the normal velocity component of the adjacent grid, u nei Indicates the mixing velocity of gases in adjacent grids, n nei Represents the surface normal vector of the adjacent mesh; represents the sound speed of the adjacent grid, p nei represents the pressure of the gas in the adjacent grid, γ nei represents the specific heat ratio of gases in adjacent grids, ρ nei Represents the density of gas in adjacent grids; represents the normal weighted average velocity component between two adjacent grids, represents the weighted average sound speed between adjacent grids;

[0133] S133. Use the HLL method to calculate the flux between the explosion grid and the adjacent grids. The calculation formula is as follows:

[0134]

[0135] Among them, S own Indicates the wave speed of the explosion grid; S nei represents the wave velocity of the adjacent grid; F own represents the flux of the explosion grid; F nei represents the flux of adjacent grids; U own Represents the conserved quantity of the explosion grid; U nei represents the conserved quantity of adjacent grids;

[0136] S134. Calculate the conservation quantity U between the explosion grid and the adjacent grids in the current time step. The calculation formula is as follows:

[0137]

[0138] Where ρ represents the mixed density of the gas in the explosion grid and the adjacent grids at the current time step; E represents the total energy of the gas in the explosion grid and the adjacent grids at the current time step;

[0139] S135. Calculate the flux F between the explosion grid and the adjacent grids at the current time step. The calculation formula is as follows:

[0140]

[0141] Where I represents the identity matrix of the explosion grid and the adjacent grids at the current time step;

[0142] S136, flux is used to update the conservation quantity. According to the first-order Euler time integration method in computational fluid dynamics theory, the conservation quantity U of the next time step is calculated. n+1 , the calculation formula is as follows:

[0143]

[0144] Among them, U n Represents the conserved quantity of the current time step; Δt represents the time step; represents the flux divergence at the current time step, and ΔV represents the volume of the grid.

[0145] In specific implementation, as a preferred embodiment of the present invention, step S14 specifically includes:

[0146] S141. During the numerical simulation of gas explosion using compressible computational fluid dynamics theory, since the density, volume fraction, specific internal energy, and specific heat ratio of various gases in the initial state (t=0) are known, the initial explosion pressure is calculated using the formula in step S125.

[0147] S142: Since the gas velocity of the explosion grid in the initial state is known, and the adjacent grid is not affected by the explosion, the weighted average velocity between the two grids is calculated. The sound velocity of the current grid can be obtained by the specific heat ratio and density of the gas and the initial explosion pressure. The weighted average sound velocity between the two grids is then calculated, and the grid interface flux is then calculated using the formula in step S133.

[0148] S143. After obtaining the flux between the grid interfaces, calculate the flux divergence Then, the first-order Euler time integration method in the formula of step S136 is used to update the conserved quantity U;

[0149] S144, the conserved quantity U includes the density, volume fraction, mixing velocity, and total energy parameters of various gases, and then the explosion pressure and interface flux at the next time step are calculated based on the new conserved quantity;

[0150] S145, continue to iterate to obtain the explosion pressure at each time step until the preset time step is reached. The calculated explosion pressure F e That is the pressure of the gas explosion on the hull.

[0151] In specific implementation, as a preferred embodiment of the present invention, step S2 specifically includes:

[0152] S21. For an ideal gas, under normal reflection, the incident overpressure is calculated using the following formula:

[0153]

[0154] in, represents the Mach number of the shock wave, S represents the speed of the shock wave, c represents the speed of sound; γ represents the specific heat ratio; p a Indicates environmental pressure;

[0155] S22. Based on the calculated incident overpressure, calculate the reflected overpressure using the following formula:

[0156]

[0157] Where Δp f represents the reflected overpressure; in this embodiment, since the speed of sound is known, the shock wave velocity is approximately the velocity calculated in the HLL method, and the reflected overpressure can be obtained by calculation. Moreover, since the specific heat ratio is also a known quantity, the reflected overpressure can be further obtained.

[0158] S23. Based on the calculated reflected overpressure, calculate the reflected pressure on the hull using the following formula:

[0159] F s =Δp f *A

[0160] Where A represents the unit area.

[0161] So far, the fluid pressure and reflected pressure per unit area of the hull have been calculated. The pressure on the hull when it is in direct contact with the explosion fluid and explosion wave is actually the sum of the fluid pressure and the reflected pressure (hereinafter referred to as the sum pressure).

[0162] When specifically implemented, as a preferred embodiment of the present invention, Figure 2 As shown, step S3 specifically includes:

[0163] S31. Obtain input parameters, including hull geometry, hull density, and pressure generated by gas explosion within a preset range;

[0164] S32. The basic principle of using the peridynamic method for hull damage assessment is to discretize the hull into a certain number of hull structural units with finite volume and finite mass. Before calculation, the hull within a preset range is discretized into hull structural units.

[0165] S33, calculating and determining the neighborhood of each hull structural unit and other hull structural units within the neighborhood;

[0166] S34, calculating various forces of the hull structural units that are not in direct contact with the explosion fluid and the explosion wave at the current time step;

[0167] S35. Based on the principles of peridynamics and Newton's second law, the movement of the hull structure unit s in direct contact with the explosion fluid and explosion wave at the current time step t is calculated as follows:

[0168]

[0169] Among them, ρ s represents the density of structural unit s; represents the acceleration of the structural unit s. In this embodiment, the hull structural units in direct contact with the explosion fluid and blast wave will be moved to new positions by the gas explosion and pressure. The displacement of these structural units can be calculated based on the change from the old to the new position. Then, the displacement is divided by the time step to obtain the velocity.

[0170] S36. In the next time step after the initial state, the quantities of the hull structural units that are not in direct contact with the explosion fluid and the explosion wave are obtained on the right side of the formula in step S35, and the density ρ of all hull structural units is s It is known that the acceleration of the hull structural unit that is not in direct contact with the explosion fluid and the explosion wave can be directly calculated by the formula in step S35. Then calculate their speed Displacement and spatial position vector

[0171] S37. Calculate the bond elongation s of all structural units and other structural units in their neighborhood at the current time step, and use the function μ used to characterize whether the bond is broken to obtain the bond breaking condition. The specific formula is as follows:

[0172]

[0173] Among them, s c represents the critical elongation of the bond;

[0174] S38, outputting the position, displacement, velocity and bond fracture status of each hull structural unit in the current time step to perform hull damage assessment of gas explosion;

[0175] S39. Check whether the preset time step is reached. If so, terminate the calculation. If not, repeat steps S34 to S38.

[0176] In specific implementation, as a preferred embodiment of the present invention, step S35 specifically includes:

[0177] S351. Calculate the resultant force of the peridynamic bond forces of other structural units on the structural unit s in its neighborhood N. The calculation formula is as follows:

[0178]

[0179] in, represents the resultant force of the peridynamic bond forces of other structural units on the structural unit s in its neighborhood N; represents the relative spatial position vector of the structural unit s relative to other structural units s′ in its neighborhood N, represents the spatial position vector of the structural unit s′, represents the spatial position vector of the structural unit s, Represents the relative displacement vector of the structural unit s to other structural units s′ in its neighborhood N, represents the displacement of the structural unit s, represents the displacement of the structural unit s′;

[0180] In the above formula, It is expressed by the following formula:

[0181]

[0182] in, represents the microscopic bond function, γ represents the radius of the neighborhood N, s represents the bond elongation, μ is used to characterize whether the bond is broken, and s c represents the critical elongation of the bond;

[0183] S352. Calculate the gas explosion and pressure on the structural unit s The calculation formula is as follows:

[0184]

[0185] For the hull particles that are not in direct contact with the explosion fluid and explosion wave, this part of the force is 0;

[0186] S353. Obtain the volume force on the structural unit s is a known item.

[0187] Example

[0188] like Figure 3 As shown, the present invention provides a ship gas explosion damage assessment method based on a gas-solid coupling model, comprising:

[0189] Step 1: Select the ship and gas explosion scenario to be assessed;

[0190] Step 2: Use professional equipment to detect the geometric model of the ship to be assessed;

[0191] Step 3: Investigate information such as gas volume fraction, density, specific internal energy, and explosion location during gas explosion;

[0192] Step 4: Input the data obtained in steps 2 and 3 into the ship gas explosion damage assessment model based on the gas-solid coupling model proposed in the present invention to obtain the ship gas explosion damage at different times;

[0193] Step 5: Based on the damage of the ship gas explosion at different times obtained in step 4, formulate a suitable rescue plan based on the ship damage assessment.

[0194] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for assessing ship gas explosion damage based on a gas-solid coupling model, characterized in that: include: S1. Based on computational fluid dynamics theory, a numerical solution model for gas explosion is constructed to calculate the pressure of gas explosion on the hull; S2. To evaluate the damage to the ship structure caused by the gas explosion, calculate the reflected pressure on the hull; S3. Based on the peridynamics method, a numerical solution model for ship damage assessment is constructed to evaluate the damage caused by gas explosion to the hull.

2. A method for assessing ship gas explosion damage based on a gas-solid coupling model according to claim 1, characterized in that: Step S1 specifically includes: S11. Obtain input parameters, including density, volume fraction, specific internal energy, and specific heat ratio of gas within a preset range, and discretize the explosion area into a finite unit grid based on the finite volume method; S12, calculating the initial explosion pressure of the explosion point grid by solving the conservation equation and combining the state equation; S13, using a flux calculation method to evaluate the flux at the interface between the explosion point grid and the adjacent grids, which is used to update the conserved variables and obtain the flow field state at the next time step; S14. Calculate the pressure of adjacent grids through the state equation according to the updated conserved variables; S15. Through the gradual iteration of time steps, the process of gas explosion pressure being transmitted to the hull is finally simulated.

3. A method for assessing ship gas explosion damage based on a gas-solid coupling model according to claim 2, characterized in that: Step S12 specifically includes: S121. Calculate the density ρ0 of the mixed gas z using the following formula: ρ0=α1ρ1+α2ρ2 Where ρ1 represents the density of diesel volatile gas x; ρ2 represents the density of air y; S122. Calculate the specific internal energy e0 of the mixed gas z using the following formula: Where, e1 represents the specific internal energy of diesel volatilized gas x, and e2 represents the specific internal energy of air y; S123. Based on the calculated density ρ0 of the mixed gas z and the specific internal energy e0 of the mixed gas z, and in accordance with computational fluid dynamics theory, calculate the pressure generated by the mixed gas z of the diesel volatile gas x and air y at the initial explosion time t0 in the explosion point grid. The calculation formula is as follows: Where p0 represents the pressure generated by the explosion of the mixed gas z; α1 represents the volume fraction of the diesel volatile gas x, and α2 represents the volume fraction of the air y. For a mixed gas composed only of these two gases, α1+α2=1; ξ1 represents the parameter related to the diesel volatile gas x; ξ2 represents the parameter related to the air y. Γ i represents the Grüneisen parameter of the i-th phase; Π1 and Π2 represent functions related to the state equation; S124. Calculate the specific heat ratio γ0 of the mixed gas z using the following formula: Among them, c p1 represents the constant pressure specific heat capacity of diesel volatile gas x; c p2 represents the constant pressure specific heat capacity of air y; c v1 represents the constant volume specific heat capacity of diesel volatile gas x; c v2 represents the specific heat capacity at constant volume of air y; S125, diesel volatile gas x, air y and mixed gas z are all regarded as ideal gases. According to the ideal gas state equation in computational fluid dynamics theory, for ideal gas, Γ i =γ i , Π i =0, calculate the pressure of the mixed gas z at the initial explosion moment, the calculation formula is as follows: p0=(γ0-1)ρ0e0.

4. A method for assessing ship gas explosion damage based on a gas-solid coupling model according to claim 2, characterized in that: Step S13 specifically includes: S131. Calculate the wave velocity S of the explosion grid own , the calculation formula is as follows: Among them, N own =u own *n own , represents the normal velocity component of the explosion grid, u own represents the mixing velocity of the gas in the explosion grid, n own Represents the surface normal vector of the explosion mesh; represents the speed of sound in the explosion grid, p own represents the pressure of the gas in the explosion grid, γ own represents the specific heat ratio of the gas in the explosion grid, ρ own Indicates the density of the gas in the explosion grid; represents the normal weighted average velocity component between the two explosion grids, represents the weighted average sound speed among explosion grids; S132. Calculate the wave speed S of adjacent grids nei , the calculation formula is as follows: Among them, N nei =u nei *n nei , represents the normal velocity component of the adjacent grid, u nei Indicates the mixing velocity of gases in adjacent grids, n nei Represents the surface normal vector of the adjacent mesh; represents the sound speed of the adjacent grid, p nei represents the pressure of the gas in the adjacent grid, γ nei represents the specific heat ratio of gases in adjacent grids, ρ nei Represents the density of gas in adjacent grids; represents the normal weighted average velocity component between two adjacent grids, represents the weighted average sound speed between adjacent grids; S133. Use the HLL method to calculate the flux between the explosion grid and the adjacent grids. The calculation formula is as follows: Among them, S own Indicates the wave speed of the explosion grid; S nei represents the wave velocity of the adjacent grid; F own represents the flux of the explosion grid; F nei represents the flux of adjacent grids; U own represents the conservation quantity of the explosion grid; U nei represents the conserved quantity of adjacent grids; S134. Calculate the conservation quantity U between the explosion grid and the adjacent grids in the current time step. The calculation formula is as follows: Where ρ represents the mixed density of the gas in the explosion grid and the adjacent grids at the current time step; E represents the total energy of the gas in the explosion grid and the adjacent grids at the current time step; S135. Calculate the flux F between the explosion grid and the adjacent grids at the current time step. The calculation formula is as follows: Where I represents the identity matrix of the explosion grid and the adjacent grids at the current time step; S136, flux is used to update the conservation quantity. According to the first-order Euler time integration method in computational fluid dynamics theory, the conservation quantity U of the next time step is calculated. n+1 , the calculation formula is as follows: Among them, U n Indicates the conserved quantity of the current time step; Δt indicates the time step; represents the flux divergence at the current time step, and ΔV represents the volume of the grid.

5. The method for assessing ship gas explosion damage based on a gas-solid coupling model according to claim 2, characterized in that: Step S14 specifically includes: S141. During the numerical simulation of gas explosion using compressible computational fluid dynamics theory, since the density, volume fraction, specific internal energy, and specific heat ratio of various gases in the initial state are known, the initial explosion pressure is calculated using the formula in step S125. S142: Since the gas velocity of the explosion grid in the initial state is known, and the adjacent grid is not affected by the explosion, the weighted average velocity between the two grids is calculated. The sound velocity of the current grid can be obtained by the specific heat ratio and density of the gas and the initial explosion pressure. The weighted average sound velocity between the two grids is then calculated, and the grid interface flux is then calculated using the formula in step S133. S143. After obtaining the flux between the grid interfaces, calculate the flux divergence Then, the first-order Euler time integration method in the formula of step S136 is used to update the conserved quantity U; S144, the conserved quantity U includes the density, volume fraction, mixing velocity, and total energy parameters of various gases, and then the explosion pressure and interface flux at the next time step are calculated based on the new conserved quantity; S145, continue to iterate to obtain the explosion pressure at each time step until the preset time step is reached. The calculated explosion pressure F e That is the pressure of the gas explosion on the hull.

6. A method for assessing ship gas explosion damage based on a gas-solid coupling model according to claim 1, characterized in that: Step S2 specifically includes: S21. For an ideal gas, under normal reflection, the incident overpressure is calculated using the following formula: in, represents the Mach number of the shock wave, S represents the speed of the shock wave, c represents the speed of sound; γ represents the specific heat ratio; p a Indicates environmental pressure; S22. Based on the calculated incident overpressure, calculate the reflected overpressure using the following formula: Where Δp f Indicates reflected overpressure; S23. Based on the calculated reflected overpressure, calculate the reflected pressure on the hull using the following formula: F s =Δp f *A Where A represents the unit area.

7. The method for assessing ship gas explosion damage based on a gas-solid coupling model according to claim 1, characterized in that: Step S3 specifically includes: S31. Obtain input parameters, including hull geometry, hull density, and pressure generated by gas explosion within a preset range; S32. discretizing the hull into a certain number of hull structural units with finite volume and finite mass, and discretizing the hull within a preset range into hull structural units before performing calculations; S33, calculating and determining the neighborhood of each hull structural unit and other hull structural units within the neighborhood; S34, calculating various forces of the hull structural units that are not in direct contact with the explosion fluid and the explosion wave at the current time step; S35. Based on the principles of peridynamics and Newton's second law, the movement of the hull structure unit s in direct contact with the explosion fluid and explosion wave at the current time step t is calculated as follows: Among them, ρ s represents the density of structural unit s; represents the acceleration of the structural unit s; S36. In the next time step after the initial state, the quantities of the hull structural units that are not in direct contact with the explosion fluid and the explosion wave are obtained on the right side of the formula in step S35, and the density ρ of all hull structural units is s It is known that the acceleration of the hull structural unit that is not in direct contact with the explosion fluid and the explosion wave can be directly calculated by the formula in step S35. Then calculate their speed Displacement and spatial position vector S37. Calculate the bond elongation s of all structural units and other structural units in their neighborhood at the current time step, and use the function μ used to characterize whether the bond is broken to obtain the bond breaking condition. The specific formula is as follows: Among them, s c represents the critical elongation of the bond; S38, outputting the position, displacement, velocity and bond fracture status of each hull structural unit in the current time step to perform hull damage assessment of gas explosion; S39. Check whether the preset time step is reached. If so, terminate the calculation. If not, repeat steps S34 to S38.

8. A method for assessing ship gas explosion damage based on a gas-solid coupling model according to claim 7, characterized in that: Step S35 specifically includes: S351. Calculate the resultant force of the peridynamic bond forces of other structural units on the structural unit s in its neighborhood N. The calculation formula is as follows: in, represents the resultant force of the peridynamic bond forces of other structural units on the structural unit s in its neighborhood N; represents the relative spatial position vector of the structural unit s relative to other structural units s′ in its neighborhood N, represents the spatial position vector of the structural unit s′, represents the spatial position vector of the structural unit s, Represents the relative displacement vector of the structural unit s to other structural units s′ in its neighborhood N, represents the displacement of the structural unit s, represents the displacement of the structural unit s′; In the above formula, It is expressed by the following formula: in, represents the microscopic bond function, γ represents the radius of the neighborhood N, s represents the bond elongation, μ is used to characterize whether the bond is broken, and s c represents the critical elongation of the bond; S352. Calculate the gas explosion and pressure on the structural unit s The calculation formula is as follows: For the hull particles that are not in direct contact with the explosion fluid and explosion wave, this part of the force is 0; S353. Obtain the volume force on the structural unit s is a known item.

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