Hydrogen fuel cell train hydrogen leakage risk early warning method based on numerical simulation

Abstract

The invention provides a hydrogen fuel cell train hydrogen leakage risk early warning method based on numerical simulation. The method comprises the following steps: establishing a three-dimensional geometric model; establishing a fluid dynamic simulation model, and performing grid division; simulating a hydrogen leakage diffusion process, calculating a hydrogen volume fraction, and analyzing to obtain a fire blast risk range database; acquiring a corresponding explosion risk range from an explosion risk range database according to the actual working condition; and different processing schemes are adopted to guarantee the running safety of the train. According to the method, the hydrogen leakage process at the hydrogen cylinder leakage opening of the hydrogen fuel cell train is subjected to simulation calculation through a numerical simulation technology, and meanwhile, the burning and explosion risk range database is established, so that the burning and explosion risk range caused by hydrogen leakage of the hydrogen fuel cell train in the actual working condition is rapidly evaluated, risk early warning is made in time, and the safety of the train is improved. By selecting the optimal scheme, the explosion risk can be remarkably reduced, and the train operation safety is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of hydrogen fuel cell train safety technology, and in particular to a hydrogen leakage risk early warning method for a hydrogen fuel cell train based on numerical simulation. Background Art

[0002] A hydrogen fuel cell train is a train that uses hydrogen as fuel and converts hydrogen into electricity through a fuel cell. A hydrogen fuel cell train uses a hydrogen cylinder array to store hydrogen, with a pressure of generally 35MPa. The compressed hydrogen in the hydrogen cylinder is transported to the fuel cell through a pipeline to drive electricity generation.

[0003] Due to the high internal pressure of hydrogen cylinders, if the hydrogen cylinders and pipelines are over-pressurized, the force exerted by hydrogen on the inner surface of the hydrogen cylinders and pipelines will increase, which may cause mechanical fracture of the cylinders and pipelines, resulting in cracks in the pipelines or instruments, leading to continuous leakage of hydrogen for a period of time. Hydrogen will continue to accumulate and may reach the flammable limit of hydrogen, causing combustion or explosion, which is very detrimental to the safety of train operation. At present, most hydrogen fuel cell trains are equipped with high-pressure safety valves (HPSV) to ensure the stability of the pressure of hydrogen cylinders, but if the high-pressure safety valve fails and causes the hydrogen cylinders and pipelines to be over-pressurized, it may still cause hydrogen leakage, causing great safety hazards.

[0004] With the gradual promotion and operation of hydrogen fuel cell trains, there is an urgent need to provide early warning for the explosion risk range caused by hydrogen leakage from hydrogen cylinder arrays, so as to facilitate a rapid assessment of the explosion risk range of the flammable gas cloud formed by the leaked hydrogen and ensure the safe operation of the trains. Summary of the invention

[0005] The purpose of the present invention is to provide a solution based on numerical simulation, which can quickly and accurately evaluate the combustion and explosion range of hydrogen leakage from a train hydrogen cylinder array under actual working conditions, and facilitate timely warning and reasonable disposal in the event of hydrogen leakage in a hydrogen fuel cell train.

[0006] In order to achieve the above object, the present invention provides a hydrogen leakage risk warning method for a hydrogen fuel cell train based on numerical simulation, comprising the following steps:

[0007] S1, respectively measuring the geometric parameters of the train, the hydrogen cylinder array on the top of the train, and the hydrogen cylinder leakage port, and establishing a three-dimensional geometric model;

[0008] S2, establishing a fluid dynamics simulation model according to the three-dimensional geometric model, and performing mesh division on the fluid dynamics simulation model;

[0009] S3, simulate and calculate the different leakage port sizes of hydrogen cylinders and the different operating environments of trains respectively, simulate the leakage and diffusion process of hydrogen in the hydrogen cylinder through the leakage port into the atmosphere, calculate the hydrogen gas volume fraction of the grid in the fluid dynamics simulation model, and analyze and obtain the explosion risk range of hydrogen leakage into the atmosphere, so as to obtain the explosion risk range database corresponding to different leakage port sizes and different operating environment conditions;

[0010] S4, when monitoring hydrogen leakage of a hydrogen fuel cell train, according to the remaining hydrogen pressure in the hydrogen cylinder under actual working conditions and the train operating environment conditions, the explosion risk range corresponding to the actual working conditions is obtained from the explosion risk range database;

[0011] S5, adopt different treatment plans according to different leakage situations to ensure the safe operation of the train.

[0012] Furthermore, in S1, geometric parameters of the exterior of the train are measured to establish a three-dimensional geometric model of the train, and geometric parameters of the hydrogen cylinder array and the hydrogen cylinder leakage port placed on the top of the train are measured to establish a three-dimensional geometric model of the hydrogen cylinder array and the hydrogen cylinder leakage port. The three-dimensional geometric model of the train is then combined with the three-dimensional geometric model of the hydrogen cylinder array and the hydrogen cylinder leakage port to obtain an overall three-dimensional geometric model.

[0013] Furthermore, in S2, a calculation domain is added outside the three-dimensional geometric model, with the leakage port of the hydrogen cylinder as the center point. The length of the calculation domain is several times greater than the length of the train. The width and height of the calculation domain refer to the design of the railway tunnel cross-section. Boolean subtraction operation is performed on the calculation domain, and the overall three-dimensional geometric model is removed from the calculation domain to form a fluid dynamics simulation model.

[0014] Furthermore, when meshing the fluid dynamics simulation model in S2, the computational domain is divided into a hydrogen bottle area and a train running area, and the mesh size in the hydrogen bottle area is set to be smaller than the mesh size in the train running area, and adaptive meshing is adopted.

[0015] Furthermore, in S3, different leakage port sizes of hydrogen cylinders are divided into several different leakage port inner diameter values ​​with fixed values ​​as intervals; the train operating environment includes different cross-sections of railway tunnels and train operating directions and operating speeds, and several different train operating environments are set according to different cross-sections and two opposite directions of train operation; the train operating speed conditions are divided into several operating speed levels according to different train operating speeds.

[0016] Furthermore, in S3, simulation calculations are performed using fluid dynamics simulation software to analyze the numerical change process of each monitored physical quantity in the hydrogen cylinder, and the changes in the flow rate and temperature of the hydrogen at the leakage port are obtained based on the changes in each physical quantity in the hydrogen cylinder; based on the flow rate and temperature conditions of the hydrogen at the leakage port of the hydrogen cylinder, the hydrogen gas volume fraction and temperature data of each grid in the calculation domain at different times are calculated.

[0017] Furthermore, the hydrogen flow rate and temperature at the leakage port in S3 are obtained based on theoretical analysis of fluid mechanics and thermodynamics knowledge. The hydrogen flow rate and temperature at the leakage port of the hydrogen bottle are imported into the fluid dynamics simulation software as a boundary condition. The fluid dynamics simulation software continuously calculates the hydrogen gas volume fraction and temperature at various locations in the entire calculation domain based on the input boundary conditions.

[0018] Furthermore, in S3, grids whose hydrogen gas volume fraction is in the range of 4% to 75% are taken as risk grids with explosion risks; the area formed by the risk grids is taken as the risk area with explosion risks, and the explosion risk range of hydrogen leakage into the atmospheric environment is obtained according to the risk area.

[0019] Furthermore, in S4, based on the explosion risk range database, linear interpolation is performed when analyzing the explosion hazard range under actual working conditions to obtain the explosion risk range corresponding to the actual working conditions.

[0020] The above scheme of the present invention has the following beneficial effects:

[0021] The hydrogen leakage risk warning method for hydrogen fuel cell trains based on numerical simulation provided by the present invention simulates and calculates the hydrogen leakage process at the leakage port of the hydrogen bottle of the hydrogen fuel cell train through numerical simulation technology, and summarizes the explosion risk range of flammable gas clouds formed by hydrogen leakage under different leakage port sizes and different train operating environments, and establishes an explosion risk range database, so as to quickly evaluate the explosion risk range caused by hydrogen leakage in hydrogen fuel cell trains under actual working conditions, make risk warnings in time, and select the optimal solution, which can significantly reduce the explosion risk and ensure the safety of train operation;

[0022] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a flow chart of the steps of the present invention;

[0024] Figure 2 This is a schematic diagram of modeling a train and a hydrogen cylinder array on top of the train in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of modeling a leakage port on the end face of a hydrogen cylinder in an embodiment of the present invention;

[0026] Figure 4 In the embodiment of the present invention, a calculation domain is added outside the three-dimensional geometric model as a flow diffusion area in the tunnel after hydrogen leakage and diffusion;

[0027] Figure 5 It is a hydrogen gas volume fraction diagram of each grid in the fluid dynamics simulation model when the leakage port size of a certain hydrogen bottle in the embodiment of the present invention and the leakage for 5s in the train running environment;

[0028] Figure 6 It is a hydrogen gas volume fraction diagram of each grid in the fluid dynamics simulation model when the leakage port size of a certain hydrogen bottle in the embodiment of the present invention and the leakage for 10s in the train running environment;

[0029] Figure 7 Graphs of flow rates in the calculation domain at different times during the leakage process of the hydrogen bottle leakage port in an embodiment of the present invention;

[0030] Figure 8 This is a comparison chart of the change curves of various values ​​under different initial pressures of hydrogen cylinders in the embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0032] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number of aspects described herein may be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein may be used to implement this device and / or practice this method.

[0033] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present disclosure, and the illustrations only show the components related to the present disclosure rather than the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in actual implementation may be changed at will, and the component layout type may also be more complicated. In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the aspects described can be practiced without these specific details.

[0034] like Figure 1 As shown, an embodiment of the present invention provides a hydrogen leakage risk warning method for a hydrogen fuel cell train based on numerical simulation, comprising the following steps:

[0035] S1, measure the geometric parameters of the train, the hydrogen cylinder array on the top of the train, and the hydrogen cylinder leakage port, and establish a three-dimensional geometric model.

[0036] Specifically, the geometric parameters of the train exterior are measured to establish a three-dimensional geometric model of the train, and the geometric parameters of the hydrogen bottle array and the hydrogen bottle leakage port placed on the top of the train are measured to establish the corresponding three-dimensional geometric model, and then the three-dimensional geometric model of the train is combined with the three-dimensional geometric models of the hydrogen bottle array and the hydrogen bottle leakage port to obtain an overall three-dimensional geometric model. Among them, the geometric parameter measurement and modeling of the train are only for the external dimensions of the train, and do not involve the measurement of the internal dimensions of the train. The geometric parameter measurement of the hydrogen bottle array and the hydrogen bottle leakage port on the top of the train is only for the measurement of the dimensions of the hydrogen bottle array placed on the top of the train and the leakage port exposed at the end face of the hydrogen bottle as the entry condition for calculating hydrogen leakage.

[0037] S2, establishing a fluid dynamics simulation model based on the three-dimensional geometric model, and meshing the fluid dynamics simulation model.

[0038] It should be noted that when performing simulation calculations, a calculation domain needs to be added outside the three-dimensional geometric model. In this embodiment, the leakage port of the hydrogen bottle is taken as the center point, the length of the calculation domain is greater than several times the length of the train, and the width and height of the calculation domain refer to the design of the railway tunnel cross section. At the same time, a Boolean subtraction operation is performed on the calculation domain to remove the overall three-dimensional geometric model from the calculation domain to form a fluid dynamics simulation model.

[0039] When meshing the fluid dynamics simulation model, the computational domain is divided into the hydrogen bottle area and the train running area. To improve the computational accuracy, the mesh size in the hydrogen bottle area is set to be smaller than the mesh size in the train running area, that is, the meshes in the two areas are encrypted to different degrees. This meshing method improves the computational speed while ensuring the computational accuracy. In addition, the adaptive meshing technology is used in this embodiment to further increase the computational efficiency while maintaining the original accuracy.

[0040] S3, simulates and calculates the different leakage port sizes of hydrogen cylinders and the different operating environments of trains respectively, simulates the leakage and diffusion process of hydrogen in the hydrogen cylinder through the leakage port into the atmosphere, calculates the hydrogen gas volume fraction of the grid in the fluid dynamics simulation model, and analyzes the explosion risk range of hydrogen leakage into the atmosphere based on this, thereby obtaining a database of explosion risk ranges corresponding to different leakage port sizes and different operating environment conditions.

[0041] In this embodiment, the leakage port inner diameter is divided into several different intervals with a fixed value; the train operation environment includes different cross sections of the railway tunnel and the train operation direction and speed. According to the different cross sections, several different train operation environments are set in two opposite directions of the train operation; according to the different train operation speeds, the train operation speed conditions are divided into several operation speed levels. Therefore, the leakage and diffusion conditions of hydrogen under the cross-sectional conditions of different tunnels of single and double lines are clarified, the influence of the leakage port inner diameter and the leakage port opening direction on the explosion risk range is clarified, and the leakage explosion risk range at different operation speeds is clarified, which can help to make the best treatment plan when dealing with different hydrogen leakage conditions.

[0042] In this embodiment, the simulation calculation using fluid dynamics simulation software includes: analyzing the numerical change process of each monitored physical quantity in the hydrogen cylinder, and obtaining the change of physical quantities such as the flow rate and temperature of hydrogen at the leakage port according to the change of each physical quantity in the hydrogen cylinder. According to the flow rate and temperature of hydrogen at the leakage port of the hydrogen cylinder, the hydrogen gas volume fraction and temperature of each grid in the calculation domain at different times are calculated.

[0043] It should be noted that the hydrogen flow rate and temperature at the leak port are obtained based on theoretical analysis of fluid mechanics and thermodynamics. The flow rate and temperature at the leak port of the hydrogen bottle are related to the hydrogen pressure in the hydrogen storage tank. As time goes by, the pressure continues to decrease, and the flow rate and temperature continue to decrease. Therefore, the hydrogen flow rate and temperature at the leak port of the hydrogen bottle are imported into the fluid dynamics simulation software as a boundary condition, which will continuously calculate the hydrogen gas integral fraction (hydrogen concentration) and temperature at various locations in the entire calculation domain based on the input boundary conditions.

[0044] Considering that the leakage of hydrogen will cause the pressure in the hydrogen bottle to continue to decrease, which will lead to a continuous decrease in the flow rate at the leak port of the hydrogen bottle. Therefore, before starting the simulation calculation, it is necessary to analyze the change of the hydrogen flow rate at the leak port of the hydrogen bottle over time according to the compressible fluid flow theory, and use this as the boundary condition of the leak port of the hydrogen bottle. According to the compressible flow theory, it can be known that under high pressure conditions, the hydrogen at the leak port of the hydrogen bottle will be in a blocked state, and its flow rate is equivalent to the local speed of sound, which is related to the initial pressure. In a very short period of time, the flow rate can be regarded as constant, so that the mass of hydrogen flowing out of the hydrogen bottle in a very short time period and the mass, pressure and temperature of the remaining hydrogen in the hydrogen bottle can be analyzed, and then based on this, the mass of hydrogen flowing out in the next time period and the flow rate of the leak port can be analyzed. By repeatedly iterating the calculation, the pressure decay curve, mass decay curve in the hydrogen bottle, and the hydrogen temperature curve and flow rate curve at the leak port of the hydrogen bottle can be obtained. Afterwards, the hydrogen flow rate and environmental conditions at the leakage port of the hydrogen cylinder obtained from theoretical analysis were input into the software as boundary conditions, and the hydrogen gas integral fraction of each grid in the model at different times was calculated.

[0045] It should be added that the hydrogen leakage and diffusion process can be described in physics by the mass conservation equation, momentum conservation equation, energy conservation equation and component transport equation. It is necessary to complete the setting of flow velocity, direction and concentration on the model boundary in the fluid dynamics simulation software in advance, and then use the fluid dynamics simulation software to iteratively solve the nonlinear control equations for the solution variables in sequence to obtain the hydrogen flow rate, hydrogen gas volume fraction, etc. of the grid in the calculation domain at different times.

[0046] In this embodiment, the grids with hydrogen gas volume fractions in the range of 4% to 75% are taken as risk grids with explosion risks; the area formed by the risk grids is taken as the risk area with explosion risks, and the explosion risk range of hydrogen leakage into the atmospheric environment can be obtained based on the risk area.

[0047] S4, when monitoring the hydrogen leakage of the hydrogen fuel cell train, the explosion risk range corresponding to the actual working condition is obtained from the explosion risk range database according to the remaining hydrogen pressure in the hydrogen cylinder under the actual working condition and the train operating environment conditions.

[0048] It should be noted that this method is based on the explosion risk ranges under several different working conditions pre-calculated through numerical simulation in the early stage and the establishment of a database. When subsequently analyzing the explosion hazard range under actual working conditions, only simple linear interpolation is required, which can greatly shorten the time for making the optimal treatment plan.

[0049] S5. Adopt appropriate treatment plans according to different leakage situations to ensure the safe operation of the train.

[0050] Therefore, the hydrogen leakage risk warning method for hydrogen fuel cell trains based on numerical simulation provided in this embodiment is adopted, and the hydrogen leakage process at the leakage port of the hydrogen bottle of the hydrogen fuel cell train is simulated and calculated through numerical simulation technology. At the same time, the explosion risk range of flammable gas cloud formed by hydrogen leakage under different leakage port sizes and different train operating environments is summarized, and an explosion risk range database is established to quickly evaluate the explosion risk range caused by hydrogen leakage in hydrogen fuel cell trains under actual working conditions, make risk warnings in time, and select the optimal solution, which can significantly reduce the explosion risk and ensure the safety of train operation.

[0051] The following is a specific example to further illustrate the effect of this method. Figure 2 As shown in Figure 1, the geometric parameters of the hydrogen fuel cell train and the hydrogen cylinder array on the top of the train are measured and modeled. Figure 3 As shown, the geometric parameters of the size of the hydrogen cylinder leakage port are measured and modeled as the inlet conditions for calculating the hydrogen leakage, and the shape of the train, the model of the hydrogen cylinder array on the top of the train and the model of the hydrogen cylinder leakage port are combined to obtain an overall three-dimensional geometric model.

[0052] like Figure 4 As shown in the figure, a calculation domain is added outside the three-dimensional geometric model as the flow diffusion area in the tunnel after the hydrogen leakage and diffusion. The calculation domain takes the hydrogen bottle leakage port as the center point. The length of the calculation domain is greater than 10 times the train length. The width and height of the calculation domain refer to the design of different railway tunnel cross sections to ensure a more realistic restoration of the actual situation of leakage in the tunnel. Boolean subtraction operation is performed on the calculation domain to remove the overall three-dimensional geometric model from the calculation domain to form a fluid dynamics simulation model. When the fluid dynamics simulation model is meshed, the calculation domain is divided into a hydrogen bottle area and a train running area. Among them, the hydrogen bottle area is divided into four encrypted areas, and the grid size gradually increases, and the train running area is divided into three encrypted areas, and the grid size gradually increases. It should be noted that the hydrogen bottle area refers to: a cylindrical area containing the hydrogen bottle leakage port and a length close to 1.6 times the length of the hydrogen bottle and a radius close to 1.5 times the radius of the hydrogen bottle; the train running area refers to: the area in the overall calculation domain except the hydrogen bottle area.

[0053] Boundary conditions are set in the fluid dynamics simulation software, including boundary conditions of the hydrogen leak port, boundary conditions of the velocity inlet, boundary conditions of the pressure outlet, boundary conditions of the wall, etc. Among them, the boundary condition of the hydrogen leak port refers to the hydrogen flow rate at the leak port of the hydrogen bottle. The boundary condition of the hydrogen leak port should be based on the compressible flow theory, the pressure in the hydrogen bottle and the size of the leak port, and the attenuation process of the hydrogen flow rate at the leak port should be analyzed. The boundary condition of the velocity inlet refers to the running speed of the train, including the running speed size and running speed direction. The boundary condition of the pressure outlet refers to the downstream boundary of the velocity inlet. The mixture of air and hydrogen flows out of the calculation domain from this boundary. The pressure on this boundary is usually set to atmospheric pressure. The boundary conditions of the wall refer to the ground, tunnel surface and train surface. The boundary type of the wall is no slip. The solution model adopts the large vortex model of turbulence, and uses a step-by-step increasing time step for time advancement.

[0054] After the setting is completed, the fluid dynamics simulation software is used to simulate and calculate the hydrogen gas volume fraction of each grid in the fluid dynamics simulation model at different times after the hydrogen leaks from the leak port of the hydrogen bottle, thereby obtaining the concentration field formed by the leakage and diffusion of hydrogen in the tunnel. Considering that explosions may occur when the volume fraction of hydrogen in the air is between 4% and 75%, the grids with hydrogen gas volume fractions in the range of 4% to 75% in the solved fluid dynamics simulation model are taken as risk grids, that is, there is a risk of combustion and explosion. By counting the risk grids that meet the conditions, the combustion and explosion risk range of the hydrogen cloud formed by the leakage of hydrogen from the leak port of the hydrogen bottle in the tunnel can be obtained.

[0055] Adjust the size of the hydrogen bottle leakage port and the train running environment, calculate the explosion risk range under different leakage port sizes and train running environments, and establish a database of explosion risk ranges under different leakage port sizes and train running environments. In this case, the leakage port size is set in the range of 2mm to 8mm (inner diameter of the circular leakage port), with 3mm as the separator, and a total of 3 different leakage port sizes are set; four train running speeds of 20, 40, 60, and 80km / h are set, and two train running directions; four different forms of tunnel cross-section area are set according to train running specifications.

[0056] Figure 5 The figure shows the size of the leaking port of a hydrogen bottle and the hydrogen gas volume fraction of each grid in the fluid dynamics simulation model when the leak lasts for 5 seconds under the train running environment. Figure 6The figure shows the size of the leakage port of a certain hydrogen bottle and the hydrogen gas volume fraction of each grid in the fluid dynamics simulation model when the leakage lasts for 10 seconds under the train running environment. It can be seen from the figure that after the hydrogen leaks, the volume fraction of hydrogen in the area behind the leakage port of the hydrogen bottle is greater than 4%, that is, there is a risk of explosion, and this area extends to the outside of the rear end of the train. In addition, it can be seen that the explosion risk range when the leakage lasts for 5 seconds is slightly larger than that of 10 seconds, so it can be considered that the risk factor of the hydrogen bottle when it leaks for 5 seconds is greater than the risk factor when it leaks for 10 seconds.

[0057] Figure 7 The figure shows the flow velocity diagram in the calculation domain at different times during the leakage process of the hydrogen cylinder leakage port. Figure 8 The figure shows a comparison of the change curves of various values ​​under different initial pressures of hydrogen cylinders, which are obtained by calculation and analysis based on the method in S3.

[0058] In this case, the trends of hydrogen concentration, temperature and speed calculated based on numerical simulation technology are very close to theoretical predictions, proving that the implementation cost of this method is low and does not require a large amount of manpower and equipment for real-time monitoring. It only requires the use of simulation software to monitor the hydrogen leakage and diffusion process under different leakage port sizes and different train operating environments.

[0059] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A hydrogen leakage risk warning method for hydrogen fuel cell trains based on numerical simulation, characterized in that: The steps include: S1, respectively measuring the geometric parameters of the train, the hydrogen cylinder array on the top of the train, and the hydrogen cylinder leakage port, and establishing a three-dimensional geometric model; S2, establishing a fluid dynamics simulation model according to the three-dimensional geometric model, and performing mesh division on the fluid dynamics simulation model; S3, simulate and calculate the different leakage port sizes of hydrogen cylinders and the different operating environments of trains respectively, simulate the leakage and diffusion process of hydrogen in the hydrogen cylinder through the leakage port into the atmosphere, calculate the hydrogen gas volume fraction of the grid in the fluid dynamics simulation model, and analyze and obtain the explosion risk range of hydrogen leakage into the atmosphere, so as to obtain the explosion risk range database corresponding to different leakage port sizes and different operating environment conditions; S4, when monitoring hydrogen leakage of a hydrogen fuel cell train, according to the remaining hydrogen pressure in the hydrogen cylinder under actual working conditions and the train operating environment conditions, the explosion risk range corresponding to the actual working conditions is obtained from the explosion risk range database; S5, adopt different treatment plans according to different leakage situations to ensure the safe operation of the train.

2. The hydrogen leakage risk warning method for hydrogen fuel cell train based on numerical simulation according to claim 1 is characterized in that: In S1, geometric parameters of the exterior of the train are measured to establish a three-dimensional geometric model of the train, and geometric parameters of the hydrogen cylinder array and the hydrogen cylinder leakage port placed on the top of the train are measured to establish a three-dimensional geometric model of the hydrogen cylinder array and the hydrogen cylinder leakage port. The three-dimensional geometric model of the train is then combined with the three-dimensional geometric models of the hydrogen cylinder array and the hydrogen cylinder leakage port to obtain an overall three-dimensional geometric model.

3. The hydrogen leakage risk warning method for hydrogen fuel cell train based on numerical simulation according to claim 2 is characterized in that: In S2, a calculation domain is added outside the three-dimensional geometric model, with the leakage port of the hydrogen cylinder as the center point. The length of the calculation domain is several times greater than the length of the train. The width and height of the calculation domain refer to the design of the railway tunnel cross section. Boolean subtraction operation is performed on the calculation domain, and the overall three-dimensional geometric model is removed from the calculation domain to form a fluid dynamics simulation model.

4. The hydrogen leakage risk warning method for hydrogen fuel cell train based on numerical simulation according to claim 3 is characterized in that: When meshing the fluid dynamics simulation model in S2, the computational domain is divided into the hydrogen bottle area and the train running area. The mesh size in the hydrogen bottle area is set smaller than the mesh size in the train running area, and adaptive meshing is used.

5. The method for early warning of hydrogen leakage risk of hydrogen fuel cell train based on numerical simulation according to claim 4 is characterized in that: In S3, different leakage port sizes of hydrogen cylinders are divided into several different leakage port inner diameter values ​​with fixed values ​​as intervals; the train operation environment includes different cross-sections of railway tunnels and train operation directions and speeds. According to the different cross-sections and two opposite directions of train operation, several different train operation environments are set; according to the different train operation speeds, the train operation speed conditions are divided into several operation speed levels.

6. The hydrogen leakage risk warning method for hydrogen fuel cell train based on numerical simulation according to claim 5 is characterized in that: In S3, fluid dynamics simulation software is used to perform simulation calculations, analyze the numerical changes of various monitored physical quantities in the hydrogen cylinder, and obtain the changes in the flow rate and temperature of hydrogen at the leakage port based on the changes in various physical quantities in the hydrogen cylinder; based on the flow rate and temperature conditions of hydrogen at the leakage port of the hydrogen cylinder, the hydrogen gas volume fraction and temperature data of each grid in the calculation domain at different times are calculated.

7. The method for early warning of hydrogen leakage risk of hydrogen fuel cell train based on numerical simulation according to claim 6 is characterized in that: The hydrogen flow rate and temperature at the leakage port in S3 are obtained based on theoretical analysis of fluid mechanics and thermodynamics. The hydrogen flow rate and temperature at the leakage port of the hydrogen bottle are imported into the fluid dynamics simulation software as a boundary condition. The fluid dynamics simulation software continuously calculates the hydrogen gas volume fraction and temperature at various locations in the entire calculation domain based on the input boundary conditions.

8. The method for early warning of hydrogen leakage risk of hydrogen fuel cell train based on numerical simulation according to claim 7 is characterized in that: In S3, grids with hydrogen gas volume fractions in the range of 4% to 75% are regarded as risk grids with explosion risks; The area formed by the risk grid is used as the risk area with explosion risk, and the explosion risk range of hydrogen leakage into the atmosphere is obtained according to the risk area.

9. The method for early warning of hydrogen leakage risk of a hydrogen fuel cell train based on numerical simulation according to any one of claims 1 to 8, characterized in that: In S4, based on the explosion risk range database, linear interpolation is performed when analyzing the explosion hazard range under actual working conditions to obtain the explosion risk range corresponding to the actual working conditions.

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