A method and system for simulating hydrogen leakage jet

Abstract

The present application provides a method and system for simulating hydrogen leakage jets, which relates to the technical field of simulating hydrogen leakage, wherein the method includes the steps of determining a virtual hole, establishing a model, setting a model, setting an equation, and running a simulation; the system includes a virtual hole determination module, a model establishment module, a model setting module, an equation setting module, and a simulation running module. The present application indirectly enlarges the real leakage hole by setting a virtual leakage hole, reduces the mesh refinement to a certain extent, and reduces the number of meshes, thereby saving computing resources.

Description

Technical Field

[0001] The present application relates to the technical field of simulating hydrogen leakage, and in particular to a method and system for simulating hydrogen leakage jet. Background Art

[0002] With the rapid development of hydrogen energy technology, hydrogen has been widely used in various fields as a clean energy. High-pressure gas cylinders are prone to hydrogen leakage due to long storage time, large capacity, and high pressure. After leakage, it is easy to spread in the air and spontaneously combust in the absence of a clearly identifiable ignition source, which can easily cause combustion, explosion and other gas fires after leakage.

[0003] Due to the high-pressure storage and transportation characteristics of hydrogen, in reality, testing high-pressure hydrogen leakage is not only time-consuming and labor-intensive, but also extremely dangerous due to factors such as excessive pressure and the inability to accurately control the leakage process. Therefore, simulation software is usually used to simulate the distribution state of hydrogen leakage.

[0004] The Chinese invention patent with application publication date of July 15, 2022 and publication number CN114757015A provides a method for determining the safe distance based on a high-pressure hydrogen pipeline leakage accident. The patent performs numerical simulation on different leakage apertures to obtain the hydrogen leakage flow rate under different aperture conditions. However, in actual software applications, since the real leakage holes are often extremely small, a large number of grids need to be laid at the real leakage holes for calculation. In addition, due to the rapid expansion and diffusion characteristics of hydrogen, the leakage behavior is difficult to predict and control. Directly simulating its leakage behavior requires a lot of computing resources and time. Summary of the invention

[0005] In order to improve computing efficiency and reduce the waste of computing resources, the present application provides a hydrogen leakage jet simulation method and system.

[0006] In the first aspect, the present application provides a hydrogen leakage jet simulation method, which adopts the following technical solution:

[0007] A hydrogen leakage jet simulation method comprises the following steps:

[0008] Determining virtual holes: including first acquisition and data processing;

[0009] First collection: collect historical data;

[0010] Data processing: Calculate the diameter of the virtual leak hole based on historical data , the calculation model is as follows:

[0011] ;

[0012] in, is the diameter of the actual leakage hole; is the density of hydrogen at the actual leak hole; is the density of hydrogen outside the high-pressure hydrogen storage and transportation equipment; is the hydrogen leakage rate at the actual leakage hole; is the hydrogen leakage rate at the virtual leak hole;

[0013] Modeling: Based on the diameter of the virtual leak hole , establish a hydrogen leakage geometric model through CFD software, and set the parameters of the hydrogen leakage geometric model;

[0014] Set the model: Set the k-ε turbulence model to simulate the turbulence phenomenon after hydrogen leakage;

[0015] Set equation: Set the component transport equation to simulate the change in the concentration of each component after hydrogen leakage. The calculation model of the component transport equation is as follows:

[0016] ;

[0017] in, It refers to the gas density after hydrogen leaks and mixes with air; is the mass fraction of component i; is the velocity vector of the current component gas; is the diffusion coefficient of component i; is the net generation rate of component i; represents the gradient operator, represents the divergence operation;

[0018] Run the simulation: Set up the CFD solver. The CFD solver uses the finite difference method to solve the component transport equation based on the k-ε turbulence model to obtain the state of hydrogen leakage.

[0019] By adopting the above-mentioned technical scheme, the present application calculates the diameter of the virtual leakage hole through historical data, establishes a hydrogen leakage geometric model based on the diameter of the virtual leakage hole, and indirectly expands the diameter of the real leakage hole of the high-pressure hydrogen storage and transportation equipment, reduces the fineness of the grid laying to a certain extent, reduces the number of grids, and thus saves a lot of computing resources; the present application uses virtual leakage holes and sets a k-ε turbulence model at the virtual leakage holes to replace the complex geometric shapes and turbulent phenomena of the real leakage holes of the high-pressure hydrogen storage and transportation equipment. While reducing the amount of calculation, it can also reduce the risk of drastic changes in flow parameters causing the flow field data to fail to converge, making calculations and numerical simulations simpler, thereby reducing the complexity of the simulation process and quickly obtaining accurate results.

[0020] Optionally, after performing the first acquisition and before performing data processing, the method further includes:

[0021] First calculation: Calculate the initial density of hydrogen inside the high-pressure hydrogen storage and transportation equipment , the calculation model is as follows:

[0022] ;

[0023] in, is the redundancy coefficient; is the hydrogen gas constant; It is the initial pressure inside the high-pressure hydrogen storage and transportation equipment; It is the initial temperature inside the high-pressure hydrogen storage and transportation equipment.

[0024] By adopting the above-mentioned technical scheme, the present application calculates an accurate initial density of hydrogen inside the high-pressure hydrogen storage and transportation equipment based on the redundancy coefficient, the hydrogen gas constant, the initial pressure inside the high-pressure hydrogen storage and transportation equipment, and the initial temperature inside the high-pressure hydrogen storage and transportation equipment, thereby providing data support for indirectly solving the density at the actual leakage hole of the high-pressure hydrogen storage and transportation equipment in subsequent steps.

[0025] Optionally, after performing the first calculation and before performing data processing, the method further includes:

[0026] Second calculation: Calculate the density of hydrogen at the actual leak hole , the calculation model is as follows:

[0027] ;

[0028] in, is the adiabatic index;

[0029] Second collection: Get the pressure at the real leak hole and temperature ;

[0030] Third calculation: Calculate the hydrogen leakage rate at the actual leak hole , the calculation model is as follows:

[0031] .

[0032] By adopting the above-mentioned technical scheme, the present application calculates the density of hydrogen at the real leakage hole of the high-pressure hydrogen storage and transportation equipment through the initial density of hydrogen inside the high-pressure hydrogen storage and transportation equipment, and collects the pressure and temperature at the real leakage hole of the high-pressure hydrogen storage and transportation equipment. The hydrogen leakage rate at the real leakage hole is calculated through the density, pressure and temperature of hydrogen at the real leakage hole, thereby providing data support for calculating the hydrogen leakage rate at the virtual leakage hole.

[0033] Optionally, after performing the third calculation and before performing data processing, the method further includes:

[0034] Fourth calculation: Calculate the density of hydrogen outside the high-pressure hydrogen storage and transportation equipment , the calculation model is as follows:

[0035] ;

[0036] in, It is the environmental pressure outside the high-pressure hydrogen storage and transportation equipment; It is the ambient temperature outside the high-pressure hydrogen storage and transportation equipment.

[0037] By adopting the above technical solution, the present application calculates the density of hydrogen outside the high-pressure hydrogen storage and transportation equipment based on the ambient pressure and ambient temperature outside the high-pressure hydrogen storage and transportation equipment, providing data support for determining the diameter of the virtual leakage hole.

[0038] Optionally, after performing the fourth calculation and before performing data processing, the method further includes:

[0039] Fifth calculation: Determine the hydrogen leakage rate at the virtual leak hole , the calculation model is as follows:

[0040] .

[0041] By adopting the above-mentioned technical scheme, the present application determines the hydrogen leakage rate at the virtual leakage hole through the hydrogen leakage rate at the real leakage hole of the high-pressure hydrogen storage and transportation equipment, the pressure at the real leakage hole of the high-pressure hydrogen storage and transportation equipment, the ambient pressure outside the high-pressure hydrogen storage and transportation equipment, and the density of hydrogen at the real leakage hole of the high-pressure hydrogen storage and transportation equipment, thereby providing data support for the accurate calculation of the diameter of the virtual leakage hole.

[0042] Optionally, before determining the virtual hole, the method further includes:

[0043] Setting boundary conditions: including setting far-field conditions and setting wall conditions;

[0044] Set far-field conditions: Set the pressure of the far-field area to atmospheric pressure; set the temperature of the far-field area to the actual temperature of the environment where the high-pressure hydrogen storage and transportation equipment is located; set the wind speed of the far-field area to the actual wind speed of the environment where the high-pressure hydrogen storage and transportation equipment is located;

[0045] Set wall conditions: Set the wall to no slip; set the wall temperature to the actual temperature of the environment where the high-pressure hydrogen storage and transportation equipment is located.

[0046] By adopting the above technical solution, the present application can significantly improve the accuracy and reliability of the hydrogen leakage jet simulation results by setting reasonable far-field conditions and wall conditions. The setting of these boundary conditions not only takes into account the physical characteristics of the actual environment, but also fully considers the various interactions and effects that may occur during the hydrogen leakage process. The pressure in the far-field area is set to atmospheric pressure so that the pressure environment outside the simulation area is consistent with the actual environment, thereby being able to more realistically reflect the interaction between hydrogen and the external environment after leakage.

[0047] Optionally, after determining the virtual hole, the method further includes:

[0048] Set the virtual hole conditions: Set the mass flow rate at the virtual leak hole to,

[0049] ;

[0050] in, is the mass flow rate at the virtual leak hole; is the flow coefficient; is the area of ​​the virtual leakage hole; is the absolute value of the pressure difference before and after the hydrogen leakage direction of the virtual leakage hole; is the initial density of hydrogen inside the high-pressure hydrogen storage and transportation equipment; is the ratio coefficient.

[0051] By adopting the above-mentioned technical scheme, the present application sets the conditions at the virtual leakage hole, and especially calculates the mass flow rate at the virtual leakage hole through a formula, and converts the mass flow rate at the virtual leakage hole into the function value of multiple parameters. By adjusting the set flow coefficient, the area of ​​the virtual leakage hole, the absolute value of the pressure difference before and after the hydrogen leakage direction of the virtual leakage hole, the initial density of hydrogen inside the high-pressure hydrogen storage and transportation equipment, and the ratio coefficient and other parameters, the mass flow rate at the virtual leakage hole can be adjusted, thereby significantly improving the accuracy and reliability of the simulation results.

[0052] Optionally, after executing the simulation, it also includes:

[0053] Meshing: Meshing the hydrogen leakage geometric model, and performing mesh encryption on the virtual leakage hole, hydrogen jet path, and hydrogen diffusion area;

[0054] Extract flow field data: extract the flow field data in each grid cell;

[0055] Verification: Calculate the error between the flow field data and the historical data, and determine whether the error is lower than a preset error threshold. If not, readjust the parameters of the hydrogen leakage geometric model and re-execute the steps of setting the model.

[0056] By adopting the above technical solution, the meshing discretizes the continuous fluid domain into a series of discrete grid units. The virtual leak hole indirectly expands the area of ​​the real leak hole. The mesh encryption processing in the virtual leak hole, hydrogen jet path and hydrogen diffusion area can not only significantly improve the simulation accuracy of these key areas, but also reduce the mesh density at the real leak hole. The flow field data contains information on physical quantities such as velocity, pressure, temperature, etc. at each position in the fluid domain. Extracting flow field data is the basis for analyzing simulation results, assessing leakage risks and formulating countermeasures. This application calculates the error between the flow field data and the historical data. By quantifying the error size, the degree of deviation between the simulation results and the historical data can be intuitively judged. If the error exceeds the preset error threshold, it means that the hydrogen leakage geometric model needs to be further optimized. The simulation results are improved by re-adjusting the parameters of the hydrogen leakage geometric model (such as grid size, physical model, etc.), and then the steps of setting the model are re-executed.

[0057] Optionally, after extracting the flow field data and before performing verification, the following steps are further included:

[0058] Convergence judgment: judge whether the flow field data converges. If so, perform verification; if not, re-execute the simulation.

[0059] By adopting the above technical solution, adding a convergence judgment step after extracting flow field data and before performing verification can further improve the stability and accuracy of CFD simulation results. If the flow field data does not converge, it means that there may be numerical oscillation or instability in the simulation process. Continuing to perform the verification step will waste computing resources and time, and the step of running the simulation needs to be re-executed. Through convergence judgment, problems can be discovered and corrected in time, reducing unnecessary waste of computing resources.

[0060] In the second aspect, the present application provides a hydrogen leakage jet simulation system, which adopts the following technical solution:

[0061] A hydrogen leak jet simulation system, comprising:

[0062] A virtual hole determination module is used to set a virtual leakage hole according to historical data and obtain the diameter of the virtual leakage hole;

[0063] A model building module, used to build a hydrogen leakage geometric model through CFD software based on the diameter of the virtual leakage hole, and set parameters of the hydrogen leakage geometric model;

[0064] The model setting module is used to set the k-ε turbulence model to simulate the turbulence phenomenon after hydrogen leakage;

[0065] The setting equation module is used to set the component transport equation and simulate the changes in the concentration of each component after hydrogen leakage;

[0066] The simulation module is run to set up the CFD solver. The CFD solver solves the component transport equation using the finite difference method based on the k-ε turbulence model to obtain the state of hydrogen leakage.

[0067] By adopting the above technical solutions, the virtual hole module is determined to set the diameter of the virtual leakage hole based on historical data, the model building module uses CFD software to establish a hydrogen leakage geometric model and set its parameters according to the diameter of the virtual leakage hole, the model setting module uses the k-ε turbulence model to simulate turbulence phenomena, the equation setting module sets the component transport equation to simulate the change of component concentration after hydrogen leakage, and the running simulation module sets and starts the CFD solver for simulation calculation. These modules work together to improve the accuracy, reliability and efficiency of the simulation results, and provide strong support for assessing the risk of hydrogen leakage and formulating countermeasures.

[0068] In summary, the present application includes at least one of the following beneficial technical effects:

[0069] 1. The present application calculates the diameter of a virtual leakage hole through historical data, and establishes a hydrogen leakage geometric model based on the diameter of the virtual leakage hole, thereby indirectly expanding the diameter of the real leakage hole of the high-pressure hydrogen storage and transportation equipment, reducing the fineness of the grid laying to a certain extent, reducing the number of grids, and thus saving a lot of computing resources; the present application uses a virtual leakage hole and sets a k-ε turbulence model at the virtual leakage hole to replace the complex geometric shape and turbulence phenomenon of the real leakage hole of the high-pressure hydrogen storage and transportation equipment. While reducing the amount of calculation, it can also reduce the risk of drastic changes in flow parameters causing the flow field data to fail to converge, making calculations and numerical simulations simpler, thereby reducing the complexity of the simulation process and quickly obtaining accurate results.

[0070] 2. The use of virtual leak holes can reduce the complexity of preliminary processing work. By simplifying the actual geometry of the real leak hole and the flow characteristics during leakage into a virtual model, the amount of calculation can be reduced while reducing the risk of flow field data not converging due to drastic changes in flow parameters, making calculations and numerical simulations easier, thereby significantly reducing the complexity of the simulation process and quickly obtaining accurate results. Through a series of calculation steps, this application provides a standardized method that can be applied to different leakage situations and environmental conditions. Researchers can use the same virtual leak hole calculation model to analyze different leakage scenarios, improve the versatility of research and application, and facilitate comparison and verification of results, thereby improving the efficiency and consistency of research.

[0071] 3. The virtual hole determination module sets the diameter of the virtual leakage hole based on historical data. The model building module uses CFD software to establish a hydrogen leakage geometry model and set its parameters according to the diameter of the virtual leakage hole. The model setting module uses the k-ε turbulence model to simulate turbulence phenomena. The equation setting module sets the component transport equation to simulate the change in component concentration after hydrogen leakage, and the run simulation module sets and starts the CFD solver for simulation calculation. These modules work together to improve the accuracy, reliability and efficiency of the simulation results, and provide strong support for assessing the risk of hydrogen leakage and formulating countermeasures. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 is a flow chart of Example 1 of the present application;

[0073] Figure 2 This is a flowchart of S2 determining a virtual hole in Example 1 of the present application;

[0074] Figure 3 It is a flowchart of the S8 simulation verification in Example 1 of the present application. DETAILED DESCRIPTION

[0075] The following combination Figures 1 to 3 This application is described in further detail.

[0076] Example 1: This example discloses a method for simulating hydrogen leakage jets, referring to Figure 1 The method includes: S1 setting boundary conditions, S2 determining virtual holes, S3 setting conditions at the virtual holes, S4 model establishment, S5 setting models, S6 setting equations, S7 running simulations, and S8 simulation verification. First, boundary conditions are set, then the diameter of the virtual leakage hole is determined based on historical data, then the conditions at the virtual leakage hole are set, then a hydrogen leakage geometric model is established, then a k-ε turbulence model is set to simulate the turbulence phenomenon after hydrogen leakage, then a component transport equation is set to simulate the changes in the concentrations of each component after hydrogen leakage, then a CFD solver is used to perform simulation calculations, and then the results of the simulation calculations are verified. The specific steps of this embodiment are as follows:

[0077] S1 sets boundary conditions, including S11 setting far-field conditions and S12 setting wall conditions. The boundary conditions refer to the physical conditions or mathematical constraints followed by hydrogen diffusion at the boundary of the simulation area.

[0078] S11 sets far-field conditions, which are used to simulate open space or a far-field area far away from the leakage source. The far-field area has the influence of wind speed, temperature and other aspects on hydrogen diffusion. In the far-field area, the initial concentration of hydrogen is set to 0. The far-field conditions include:

[0079] Set the pressure in the far field region to standard atmospheric pressure.

[0080] The temperature of the far-field area is set to the actual temperature of the environment where the high-pressure hydrogen storage and transportation equipment is located. The actual temperature of the environment can be obtained through the temperature sensor.

[0081] The wind speed in the far field area is set to the actual wind speed in the environment where the high-pressure hydrogen storage and transportation equipment is located, which is used to simulate the natural wind in the environment. This is achieved by defining the velocity inlet boundary condition, where the direction and magnitude of the velocity vector are determined according to the meteorological conditions.

[0082] S12 sets the wall conditions. The wall conditions are used to simulate the influence of solid boundaries on fluid flow, such as buildings, ground, pipe walls, etc. The wall conditions include:

[0083] No-slip condition: Set the wall to no-slip.

[0084] Temperature: Set the wall temperature to the actual temperature of the environment where the high-pressure hydrogen storage and transportation equipment is located.

[0085] like Figure 2 As shown, the S2 determines the virtual hole, including S21 first acquisition, S22 first calculation, S23 second calculation, S24 second acquisition, S25 third calculation, S26 fourth calculation, S27 fifth calculation and S28 data processing.

[0086] S21 is the first collection, collecting historical data.

[0087] S22 First calculation: calculate the initial density of hydrogen inside the high-pressure hydrogen storage and transportation equipment , the calculation model is as follows:

[0088] ;

[0089] in, is the redundancy coefficient, in this embodiment, ; is the hydrogen gas constant, and its calculation model is as follows:

[0090] ;

[0091] in, is the universal gas constant, which is ; is the molar mass of hydrogen, which is ; According to the above content, it is calculated that ; It is the initial pressure inside the high-pressure hydrogen storage and transportation equipment, in Pa; It is the initial temperature inside the high-pressure hydrogen storage and transportation equipment, unit is K.

[0092] S23 Second calculation: calculate the density of hydrogen at the actual leak hole of the high-pressure hydrogen storage and transportation equipment , the calculation model is as follows:

[0093] ;

[0094] in, is the adiabatic index, which is 1.4 in this embodiment.

[0095] In other embodiments, since the interaction between molecules becomes significant under high pressure conditions, in order to accurately describe the state of hydrogen under high pressure, the actual gas state equation is used to calculate the density of hydrogen at the actual leak hole of the high-pressure hydrogen storage and transportation equipment. , taking the van der Waals equation as an example, its calculation model is as follows:

[0096] ;

[0097] in, It is the pressure at the actual leakage hole of the high-pressure hydrogen storage and transportation equipment, in Pa; is the molar volume, unit is m³ / mol; The hydrogen gas constant, its value and calculation model are the same as those of the first calculation of S22; is the temperature at the actual leakage hole of the high-pressure hydrogen storage and transportation equipment, in K; a and b are constants related to gas properties, a reflects the attraction between hydrogen molecules, and b represents the effective volume occupied by each hydrogen molecule. In this embodiment, , .

[0098] Using the above formula, we can obtain the molar volume Then, the density of hydrogen at the actual leakage hole of the high-pressure hydrogen storage and transportation equipment is obtained according to the following calculation model: ,

[0099] ;

[0100] in, is the molar mass of hydrogen, which is .

[0101] S24 second collection, extract the pressure at the real leakage hole of high-pressure hydrogen storage and transportation equipment and temperature , through CFD software, based on historical data simulation, obtain its pressure and temperature .

[0102] In other embodiments, the pressure The temperature is collected by the pressure sensor The collected pressure is collected by the temperature sensor and temperature It is stored in the database of historical data and is directly called from the database of historical data when used.

[0103] S25 The third calculation is to calculate the hydrogen leakage rate at the actual leakage hole of the high-pressure hydrogen storage and transportation equipment , the calculation model is as follows:

[0104] .

[0105] In other embodiments, the hydrogen leakage rate at the real leakage hole is It can also be obtained using the following calculation model:

[0106] ;

[0107] in, is the flow coefficient, the flow coefficient The value range of is 0.6-0.8; is the area of ​​the actual leakage hole, in m 2 , get its value in historical data; is the absolute value of the pressure difference before and after the hydrogen leakage direction of the real leakage hole, The front and back of the hydrogen leakage direction of the real leakage hole is based on the direction of hydrogen leakage as the front, that is, the outside of the high-pressure hydrogen storage and transportation equipment is the front, and the inside of the high-pressure hydrogen storage and transportation equipment is the back.

[0108] S26 Fourth calculation: calculate the density of hydrogen outside the high-pressure hydrogen storage and transportation equipment , the calculation model is as follows:

[0109] ;

[0110] in, It is the environmental pressure outside the high-pressure hydrogen storage and transportation equipment; It is the ambient temperature outside the high-pressure hydrogen storage and transportation equipment.

[0111] In other embodiments, a numerical model of hydrogen leakage or hydrogen flow is established based on historical data through CFD software, and the density of hydrogen outside the high-pressure hydrogen storage and transportation equipment is obtained through simulation. .

[0112] S27 Fifth calculation, determining the hydrogen leakage rate at the virtual leakage hole , the calculation model is as follows:

[0113] .

[0114] In other embodiments, the hydrogen leakage rate at the virtual leakage hole is , can also be obtained through the following calculation model,

[0115] ;

[0116] in, is the flow coefficient, the flow coefficient The value range of is 0.6-0.8; is the area of ​​the virtual leak hole, and A is greater than B, in m 2 ; is the absolute value of the pressure difference before and after the hydrogen leakage direction of the virtual leakage hole (i.e. the direction from the inside to the outside of the high-pressure hydrogen storage and transportation equipment is the front, and vice versa, the back), is the density of hydrogen at the virtual leak hole. Since the virtual leak hole is close to the real leak hole (in this embodiment, the distance between the real leak hole and the virtual leak hole does not exceed 5 cm), , similarly ; is the compensation value, which is -0.1. is the diameter of the virtual leak hole The polynomial is directly substituted into the data processing of step S28 to solve the problem about The quadratic equation of one variable can be obtained The numerical value of .

[0117] S28 data processing, calculate the diameter of the virtual leak hole based on the data calculated by S22-S27 , the calculation model is as follows:

[0118] ;

[0119] in, The density of hydrogen at the actual leakage hole of the high-pressure hydrogen storage and transportation equipment obtained by the second calculation in S23; The density of hydrogen outside the high-pressure hydrogen storage and transportation equipment obtained by the fourth calculation in S26; The hydrogen leakage rate at the actual leakage hole of the high-pressure hydrogen storage and transportation equipment obtained by the third calculation in S25; The hydrogen leakage rate at the virtual leakage hole obtained by the fifth calculation in S27; Based on , query the historical data to find out the actual leakage hole diameter.

[0120] S3 sets the conditions at the virtual hole. In the simulation of hydrogen leakage, the leakage hole is usually set as the mass flow inlet boundary condition. This embodiment simulates the real leakage hole of the high-pressure hydrogen storage and transportation equipment by setting the conditions at the virtual leakage hole, that is, setting the conditions at the real leakage hole at the virtual leakage hole.

[0121] The mass flow rate at the virtual leak hole is set to,

[0122] ;

[0123] in, is the mass flow rate at the virtual leak hole, unit: kg / s; is the flow coefficient, the flow coefficient The value range of is 0.6-0.8; is the area of ​​the virtual leak hole, calculated by the diameter of the virtual leak hole, unit: m 2 ; is the absolute value of the pressure difference before and after the virtual leak hole; in this embodiment, the absolute value of the pressure difference before and after the virtual leak hole It is approximately the difference between the pressure inside the tank and the external environment pressure, that is, ; is the initial density of hydrogen inside the high-pressure hydrogen storage and transportation equipment, unit: kg / m 3 ; is the ratio coefficient. In this embodiment, Since the external environment pressure is much lower than the pressure inside the tank, it can be approximately considered , so that The term is simplified to 1.

[0124] S4 model establishment, based on the diameter of the virtual leak hole , establish a hydrogen leakage geometric model through CFD software, and set the parameters of the hydrogen leakage geometric model.

[0125] S5 sets the model. In the CFD software, the k-ε turbulence model is selected to simulate the turbulence phenomenon after hydrogen leakage.

[0126] S6 sets an equation, sets a component transport equation, and simulates the change in the concentration of each component after hydrogen leakage. The components include: hydrogen, nitrogen, oxygen, etc. The calculation model of the component transport equation is as follows:

[0127] ;

[0128] in, It refers to the density of hydrogen mixed with air after hydrogen leaks, in kg / m 3 ; is the mass fraction of component i; is the velocity vector of the current component gas; is the diffusion coefficient of component i, which describes the ability of the current component to diffuse in the fluid. is the net generation rate of component i. For a simple leakage simulation, if no chemical reaction occurs, . represents the gradient operator, Represents the divergence operation.

[0129] In CFD software, the component transport equation will be built into the CFD solver as part of the solution. It only requires setting the initial conditions (such as the initial concentration distribution of hydrogen when the leak starts), boundary conditions (far-field conditions and wall conditions), and physical properties of the fluid (such as density, diffusion coefficient, etc.).

[0130] S7 runs the simulation and sets up the CFD solver. The CFD solver uses the finite difference method to solve the component transport equation based on the k-ε turbulence model to obtain the state of hydrogen leakage.

[0131] like Figure 3 As shown, the S8 simulation verification includes S81 grid division, S82 flow field data extraction, S83 convergence judgment and S84 verification.

[0132] S81 meshing, using CFD software to mesh the hydrogen leakage geometry model, so that the overall structure of the hydrogen leakage geometry model is evenly covered. Mesh encryption is performed on the virtual leak hole, hydrogen jet path (the direct flow trajectory formed after hydrogen is ejected from the virtual leak hole) and hydrogen diffusion area (the wide area affected by hydrogen diffusion in the surrounding environment) to more accurately capture the details of hydrogen flow, such as velocity gradient, pressure change, concentration distribution and other key parameters.

[0133] S82 extracts flow field data. Using CFD software, the flow field data in each grid cell is extracted. The flow field data includes velocity vector, pressure distribution, temperature field, hydrogen concentration distribution, etc., which together constitute a complete physical field that describes hydrogen leakage and its subsequent flow diffusion process.

[0134] S83 Convergence judgment, judge whether the flow field data converges. The basis for judging whether it converges is: by comparing the results of several consecutive iterations (i.e., the flow field data extracted by CFD software in recent times), check whether the changes in key parameters (such as velocity, pressure, concentration, etc.) are less than the preset convergence standard. If it is judged to be converged, it means that the current simulation results are stable enough to enter the next verification stage; if it is not converged, it is necessary to recheck and adjust the boundary condition settings, such as inlet velocity, outlet pressure, wall conditions, etc., and then re-execute S7 to run the simulation until the convergence standard is reached.

[0135] Convergence means that as the number of calculation iterations increases, the flow field data gradually becomes stable and no longer changes significantly.

[0136] S84 verification calculates the error between flow field data and historical data. The calculated error involves the comparison of multiple key parameters, such as the maximum deviation, average deviation, and root mean square error of hydrogen concentration distribution.

[0137] It is determined whether the error is lower than a preset error threshold. If the errors of all key parameters are lower than the threshold, it is considered that the simulation result is in good agreement with the historical data, and the hydrogen leakage jet simulation result is verified. Otherwise, the parameters of the hydrogen leakage geometric model are readjusted. After adjusting the parameters, S5 is re-executed to set the model.

[0138] The present embodiment provides a method for simulating a hydrogen leakage jet, including determining a virtual hole, including collecting historical data and processing it to calculate the diameter of the virtual leakage hole, which is obtained based on a complex relationship between the characteristics of the real leakage hole and parameters such as hydrogen density and leakage rate. Subsequently, based on the diameter of the virtual leakage hole, a hydrogen leakage geometric model is constructed by CFD software and its parameters are set. Next, the ks turbulence model is set to simulate the turbulence phenomenon after the leakage, and the component transport equation is set to simulate the changes in the concentration of hydrogen and each component. Finally, the CFD solver is configured and started to perform simulation calculations to obtain detailed flow field and concentration distribution results of the hydrogen leakage.

[0139] Embodiment 2: This embodiment discloses a hydrogen leakage jet simulation system, the system comprising:

[0140] The virtual hole determination module is responsible for accurately setting the location, shape and key parameter of the virtual leak hole, namely the diameter, based on historical data or experimental observation results. As the source of hydrogen leakage, the characteristics of the virtual leak hole will directly affect the subsequent simulation results of hydrogen flow and diffusion. This module will first collect and analyze relevant historical data, which comes from previous leakage event records, laboratory simulation experiments or on-site investigation reports. And use historical data, combined with engineering experience and professional knowledge, to estimate the diameter of the virtual leak hole.

[0141] In some cases, if the historical data is rich and accurate enough, reverse engineering or data fitting techniques can be used to optimize the setting of virtual leak hole parameters. Ultimately, the determined virtual leak hole diameter will be passed to the model building module as the basis for building a hydrogen leak geometry model.

[0142] The model building module is used to receive the virtual leakage hole diameter from the virtual hole determination module, and then use the virtual leakage hole diameter to build a detailed hydrogen leakage geometric model through CFD (computational fluid dynamics) software. This module not only needs to consider the location and size of the virtual leakage hole, but also needs to finely construct the hydrogen leakage geometric model according to the actual physical environment, such as the surrounding space structure, obstacle distribution, ventilation conditions, etc. In the process of establishing the hydrogen leakage geometric model, a series of key model parameters need to be set, such as fluid properties (hydrogen density, viscosity, thermal conductivity, etc.) and initial conditions (initial temperature, pressure, etc.). The setting of these parameters will directly affect the accuracy and reliability of the simulation results.

[0143] The model setting module is used to select a suitable turbulence model for hydrogen leakage simulation to accurately simulate the complex turbulence phenomenon after hydrogen leakage. Among the many turbulence models, the k-ε (k-epsilon) model is widely used due to its high computational efficiency and wide range of applications. This module integrates the k-ε turbulence model into the CFD software and sets the corresponding model parameters, such as the initial values ​​of the turbulent kinetic energy k and the turbulent dissipation rate ε, boundary conditions, and solution strategies. Through reasonable parameter settings, the simulation results can accurately reflect the characteristics of the turbulent field after hydrogen leakage, such as velocity fluctuations, energy dissipation, and vortex structures.

[0144] The setting equation module is responsible for introducing the component transport equation into the CFD model to simulate the changes in the concentration of each component after hydrogen leakage. Hydrogen leakage not only involves the flow of fluid, but also the diffusion and mixing of gas components. Therefore, this module will construct the component transport equation based on basic principles such as the law of conservation of mass and Fick's law. By solving the component transport equation, the temporal and spatial distribution of the concentration of each component during hydrogen leakage can be calculated, providing an important basis for assessing leakage risks and formulating emergency measures.

[0145] The simulation module is responsible for setting various parameters of the CFD solver, such as the solution algorithm, iteration step, convergence standard, etc., and starting the solver for simulation calculation. During the simulation, the CFD solver will solve the component transport equations by the finite difference method based on the model, equations and parameters set in the previous module to obtain detailed simulation results of the hydrogen leakage process. These results include the velocity distribution, pressure distribution, temperature distribution of the flow field, and the temporal and spatial changes of the concentration of each component.

[0146] The present embodiment provides a hydrogen leakage jet simulation system, which includes: a virtual hole determination module, which sets the virtual leakage hole diameter of the hydrogen leakage based on historical data; followed by a model establishment module, which uses the diameter of the virtual leakage hole to construct a hydrogen leakage geometric model through CFD software and set relevant parameters; a model setting module selects and configures a k-ε turbulence model to simulate the turbulence phenomenon after leakage; an equation setting module is responsible for introducing component transport equations to simulate changes in the concentration of hydrogen and each component; finally, a simulation run module is set and a CFD solver is started to perform simulation calculations to obtain detailed flow field and concentration distribution results of the hydrogen leakage process.

[0147] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A hydrogen leakage jet simulation method, characterized in that: include: Setting boundary conditions: including setting far-field conditions and setting wall conditions; Set far-field conditions: Set the pressure of the far-field area to atmospheric pressure; set the temperature of the far-field area to the actual temperature of the environment where the high-pressure hydrogen storage and transportation equipment is located; set the wind speed of the far-field area to the actual wind speed of the environment where the high-pressure hydrogen storage and transportation equipment is located; Set wall conditions: Set the wall to no slip; Set the wall temperature to the actual temperature of the environment where the high-pressure hydrogen storage and transportation equipment is located; Determining virtual holes: including first acquisition and data processing; First collection: collect historical data; Data processing: Calculate the diameter of the virtual leak hole based on historical data , the calculation model is as follows: ； in, is the diameter of the actual leakage hole; is the density of hydrogen at the actual leak hole; is the density of hydrogen outside the high-pressure hydrogen storage and transportation equipment; is the hydrogen leakage rate at the actual leakage hole; is the hydrogen leakage rate at the virtual leak hole; Set the virtual hole conditions: Set the mass flow rate at the virtual leak hole to, ； in, is the mass flow rate at the virtual leak hole; is the flow coefficient; is the area of ​​the virtual leakage hole; is the absolute value of the pressure difference before and after the hydrogen leakage direction of the virtual leakage hole; is the initial density of hydrogen inside the high-pressure hydrogen storage and transportation equipment; is the ratio coefficient; Modeling: Based on the diameter of the virtual leak hole , establish a hydrogen leakage geometric model through CFD software, and set the parameters of the hydrogen leakage geometric model; Set the model: Set the k-ε turbulence model to simulate the turbulence phenomenon after hydrogen leakage; Set equation: Set the component transport equation to simulate the change in the concentration of each component after hydrogen leakage. The calculation model of the component transport equation is as follows: ； in, It refers to the gas density after hydrogen leaks and mixes with air; is the mass fraction of component i; is the velocity vector of the current component gas; is the diffusion coefficient of component i; is the net generation rate of component i; represents the gradient operator, represents the divergence operation; Run the simulation: Set up the CFD solver. The CFD solver uses the finite difference method to solve the component transport equation based on the k-ε turbulence model to obtain the state of hydrogen leakage.

2. The hydrogen leakage jet simulation method according to claim 1, characterized in that: After performing the first acquisition and before performing data processing, the method further includes: First calculation: Calculate the initial density of hydrogen inside the high-pressure hydrogen storage and transportation equipment , the calculation model is as follows: ； in, is the redundancy coefficient; is the hydrogen gas constant; It is the initial pressure inside the high-pressure hydrogen storage and transportation equipment; It is the initial temperature inside the high-pressure hydrogen storage and transportation equipment.

3. The hydrogen leakage jet simulation method according to claim 2, characterized in that: After performing the first calculation and before performing data processing, the method further includes: Second calculation: Calculate the density of hydrogen at the actual leak hole , the calculation model is as follows: ； in, is the adiabatic index; Second collection: Get the pressure at the real leak hole and temperature ; Third calculation: Calculate the hydrogen leakage rate at the actual leak hole , the calculation model is as follows: 。 4. The hydrogen leakage jet simulation method according to claim 3, characterized in that: After performing the third calculation and before performing data processing, the method further includes: Fourth calculation: Calculate the density of hydrogen outside the high-pressure hydrogen storage and transportation equipment , the calculation model is as follows: ； in, It is the environmental pressure outside the high-pressure hydrogen storage and transportation equipment; It is the ambient temperature outside the high-pressure hydrogen storage and transportation equipment.

5. The hydrogen leakage jet simulation method according to claim 4, characterized in that: After performing the fourth calculation and before performing data processing, the method further includes: Fifth calculation: Determine the hydrogen leakage rate at the virtual leak hole , the calculation model is as follows: 。 6. The hydrogen leakage jet simulation method according to claim 1, characterized in that: After executing the run simulation, it also includes: Meshing: Meshing the hydrogen leakage geometric model, and performing mesh encryption on the virtual leakage hole, hydrogen jet path, and hydrogen diffusion area; Extract flow field data: extract the flow field data in each grid cell; Verification: Calculate the error between the flow field data and the historical data, and determine whether the error is lower than a preset error threshold. If not, readjust the parameters of the hydrogen leakage geometric model and re-execute the steps of setting the model.

7. The hydrogen leakage jet simulation method according to claim 6, characterized in that: After extracting flow field data and before performing verification, it also includes: Convergence judgment: judge whether the flow field data converges. If so, perform verification; if not, re-execute the simulation.

8. A hydrogen leakage jet simulation system, the system being applicable to the method according to any one of claims 1 to 7, characterized in that: include: A virtual hole determination module is used to set a virtual leakage hole according to historical data and obtain the diameter of the virtual leakage hole; A model building module, used to build a hydrogen leakage geometric model through CFD software based on the diameter of the virtual leakage hole, and set parameters of the hydrogen leakage geometric model; The model setting module is used to set the k-ε turbulence model to simulate the turbulence phenomenon after hydrogen leakage; The setting equation module is used to set the component transport equation and simulate the changes in the concentration of each component after hydrogen leakage; The simulation module is run to set up the CFD solver. The CFD solver solves the component transport equation using the finite difference method based on the k-ε turbulence model to obtain the state of hydrogen leakage.

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