Numerical simulation method and system for stability of high-speed train under wind shear

Abstract

This invention relates to the field of engineering technology and discloses a numerical simulation method and system for fluid-structure interaction of high-speed train stability under wind shear. The method includes: establishing a high-speed train system dynamic model based on system dynamics data, and determining the car body following marker points within the high-speed train system dynamic model; loading the time-varying aerodynamic load input function using force element 93, and outputting the motion state parameters of the car body and key components to the high-speed train system dynamic model to obtain the loaded high-speed train system dynamic model; outputting the loaded high-speed train system dynamic model as an FMU format file; establishing an aerodynamic model based on aerodynamic data, and determining the model moment point within the aerodynamic model, ensuring that the position of the model moment point coincides with the car body following marker points; establishing two physical continuums within the aerodynamic model; and simultaneously outputting aerodynamic performance parameters and dynamic performance parameters.

Description

Technical Field

[0001] This invention relates to the field of engineering technology, and in particular to a method and system for numerical simulation of the stability of high-speed trains under wind shear via fluid-structure interaction. Background Technology

[0002] As the operating and design speeds of high-speed trains continue to increase, the fluid-structure interaction effect becomes more prominent. In particular, with more and more high-speed railway networks extending into areas prone to strong winds, the accurate assessment and control of train operation safety risks and stability in windy environments has become a key technical bottleneck restricting the development of even higher-speed train systems. Existing traditional methods cannot deeply reveal and simulate the strong fluid-structure interaction (FSI) effect of high-speed trains under high wind conditions, exhibiting three limitations: First, existing wind tunnel tests struggle to reproduce the dynamic coupling effect between the real atmospheric boundary layer wind field and train motion, and scaled-down models cannot accurately reflect the feedback mechanism of aerodynamic loads on the attitude motion of the car body and frame. Second, current conventional train aerodynamic performance analyses treat the train model as static, neglecting the dynamic interaction between aerodynamic loads and the attitude motion of the car body and frame, leading to significant deviations in the predicted flow field evolution between the car body and the track surface, load fluctuation characteristics in the bogie region, pantograph aerodynamic lift, and aerodynamic loads on the car body structure and other key parameters. Furthermore, existing numerical assessments of the operational safety risks and stability of high-speed trains in high wind environments often employ a unidirectional FSI strategy, statically mapping fluid calculation results to the dynamic model for analysis, resulting in significant discrepancies between the predicted dynamic performance and actual conditions. Therefore, there is an urgent need to develop a numerical research method that enables bidirectional FSI studies of the aerodynamic and dynamic performance of high-speed trains under high wind conditions, providing innovative methodological support for the wind-resistant design of higher-speed trains. Summary of the Invention

[0003] This invention provides a numerical simulation method and system for fluid-structure interaction of high-speed train stability under wind shear, in order to solve the problems that existing numerical research methods cannot reflect the dynamic interaction between aerodynamic loads and the attitude motion of the car body, frame, etc., and have low prediction accuracy.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] In a first aspect, the present invention provides a fluid-structure interaction numerical simulation method for the stability of high-speed trains under wind shear, comprising:

[0006] S1. Define the mass and moment of inertia of the car body, bogie, and wheelset, the stiffness and damping of the suspension system, the nonlinear contact geometry of the wheel and rail, and the creep force as system dynamics data. Based on the system dynamics data, establish a high-speed train system dynamics model and determine the car body following marker points in the high-speed train system dynamics model.

[0007] S2. Define five time-varying aerodynamic load input functions in the high-speed train system dynamics model: lateral force, lift, roll moment, pitching moment, and yaw moment. Load the time-varying aerodynamic load input functions through force element No. 93 and output the motion state parameters of the car body and key components to the high-speed train system dynamics model to obtain the high-speed train system dynamics model after loading the load.

[0008] S3. Output the dynamic model of the high-speed train system after loading in S2 as an FMU format file;

[0009] S4. Define the computational domain, the proportion of the windward and leeward sides, and the proportion of the front and rear ends of the vehicle as aerodynamic data. Based on the aerodynamic data, establish an aerodynamic model and determine the model's moment point in the aerodynamic model so that the position of the model's moment point is consistent with the vehicle's following marker point.

[0010] S5. Establish two physical continuums in the aerodynamic model, namely the inner continuum and the outer continuum. The inner continuum simulates the flow field around the aerodynamic model, and the outer continuum F is linked to the FMU format file of S3.

[0011] S6, the aerodynamic model and the high-speed train system dynamics model exchange data in real time through the FMI interface of the two physical continuums. The aerodynamic model inputs five aerodynamic force and torque monitoring values ​​to the high-speed train system dynamics model, and the dynamics model feeds back five degrees of freedom motion parameters of the car body: lateral movement, vertical movement, side roll, pitching, and yaw, and outputs aerodynamic performance parameters and dynamic performance parameters simultaneously.

[0012] Optionally, in S1, the wheel-rail nonlinear contact geometry includes the effects of unbalanced lateral acceleration and incoming wind direction, and the vehicle body following marker points are used to achieve accurate application of aerodynamic loads on the dynamic model.

[0013] Optionally, in S2, the motion state parameters include the linear velocity, angular velocity, linear acceleration, and angular acceleration of the vehicle body and bogie.

[0014] Optionally, in S4, the blocking ratio of the computing domain is less than 5%, the ratio of the geometric regions of the windward side and the leeward side of the vehicle body is 1:2, and the ratio of the front end and the rear end of the vehicle body is 1:3.

[0015] The computational domain boundary is defined as follows: the front end and the windward side are the velocity inlet, the rear end and the leeward side are the pressure outlet, the ground is the fixed wall, and the remaining surfaces are symmetry surfaces.

[0016] Optionally, in S4, a four-layer mesh encryption strategy is adopted to handle the multi-degree-of-freedom motion of the vehicle body. The first layer encrypts the bottom area of ​​the vehicle body and the range is greater than the length of the train. The remaining three layers are encrypted step by step around the train. The mesh length-to-width ratio is ≤2:1. 10 to 15 boundary layers are set near the surface of the vehicle body.

[0017] Optionally, in S5, the inner continuum is used for defining the aerodynamic turbulence model and simulating the effects of gravity. When simulating the effects of gravity, the gravitational acceleration is defined as 9.8 m / s², and the reference air pressure is one normal atmosphere. The outer continuum is used to link the FMU model, and the FMI interface is a 2.0 interface.

[0018] Optionally, in S5, the FMI collaborative simulation protocol is a two-way data exchange channel. The two-way real-time data exchange channel includes: a first type of parameter and a second type of parameter. The first type of parameter is the dynamic state variable output to the aerodynamic numerical simulation model in real time, which is used to realize the embedding and parameterized synchronous modeling of dynamic parameters in the train aerodynamic numerical simulation model. The second type of parameter is the motion characteristic parameter collected in real time through the monitoring points of vehicle system component structures such as the car body and bogie, which is used to realize the evolution of vehicle dynamic behavior under aerodynamic action and feed it back to the aerodynamic numerical model to realize the real-time update of the motion state of the car body and key components.

[0019] Optionally, in S6, the aerodynamic performance parameters include pressure distribution, flow field velocity, and aerodynamic load time history, while the dynamic performance parameters include suspension system force, wheel load reduction rate, derailment coefficient, and overturning coefficient.

[0020] Secondly, embodiments of this application provide a fluid-structure interaction numerical simulation system for the stability of a high-speed train under wind shear, including a processor and a memory;

[0021] Memory, used to store computer programs;

[0022] When a processor executes a program stored in memory, it implements any of the steps of the method described in the first aspect.

[0023] Beneficial effects:

[0024] The present invention provides a numerical simulation method for high-speed train stability under wind shear. Through a collaborative simulation framework based on the FMI2.0 protocol, the present invention breaks through the limitations of traditional one-way fluid-structure interaction methods and realizes bidirectional real-time interaction between aerodynamic loads and vehicle dynamic behavior. This significantly improves the accuracy of aerodynamic performance simulation of high-speed trains in windy conditions. The synchronous update of dynamic parameters and aerodynamic loads can accurately capture the dynamic coupling effect between the vehicle body and the flow field, providing reliable data support for wind-resistant design.

[0025] Meanwhile, the adoption of a four-layer progressively finer mesh strategy and a boundary layer subdivision of 10-15 layers near the vehicle body surface effectively improves the analytical capability of complex flow fields around the vehicle body. By combining the unsteady SST k−ω turbulence model with the IDDES method, the dynamic interaction between atmospheric boundary layer wind field and train motion is accurately simulated while ensuring computational efficiency, reducing errors caused by mesh distortion or simplification of turbulence models. Attached Figure Description

[0026] Figure 1 This is a flowchart of a preferred embodiment of the fluid-structure interaction numerical simulation method for high-speed train stability under wind shear according to the present invention. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "an" or "a" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "connected" or "linked" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up," "down," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0029] It should be understood that the fluid-structure interaction numerical simulation method for high-speed train stability under wind shear proposed in this application can be applied to the numerical simulation of the aerodynamic and dynamic performance of high-speed trains, providing innovative methodological support for the wind-resistant design of higher-speed trains. It is especially suitable for the fluid-structure interaction numerical simulation and numerical simulation of high-speed train stability under wind shear in windy environments. This is only an example and is not intended to limit the scope of the application.

[0030] Please see Figure 1 This application provides a fluid-structure interaction numerical simulation method for high-speed train stability under wind shear, including:

[0031] S1. Define the mass and moment of inertia of the car body, bogie, and wheelset, the stiffness and damping of the suspension system, the nonlinear contact geometry of the wheel and rail, and the creep force as system dynamics data. Based on the system dynamics data, establish a high-speed train system dynamics model and determine the car body following marker points in the high-speed train system dynamics model.

[0032] S2. Define five time-varying aerodynamic load input functions in the high-speed train system dynamics model: lateral force, lift, roll moment, pitching moment, and yaw moment. Load the time-varying aerodynamic load input functions through force element No. 93 and output the motion state parameters of the car body and key components to the high-speed train system dynamics model to obtain the high-speed train system dynamics model after loading the load.

[0033] S3. Output the dynamic model of the high-speed train system after loading in S2 as an FMU format file;

[0034] S4. Define the computational domain, the proportion of the windward and leeward sides, and the proportion of the front and rear ends of the vehicle as aerodynamic data. Based on the aerodynamic data, establish an aerodynamic model and determine the model's moment point in the aerodynamic model so that the position of the model's moment point is consistent with the vehicle's following marker point.

[0035] S5. Establish two physical continuums in the aerodynamic model, namely the inner continuum and the outer continuum. The inner continuum simulates the flow field around the aerodynamic model, and the outer continuum F is linked to the FMU format file of S3.

[0036] S6, the aerodynamic model and the high-speed train system dynamics model exchange data in real time through the FMI interface of the two physical continuums. The aerodynamic model inputs five aerodynamic force and torque monitoring values ​​to the high-speed train system dynamics model, and the dynamics model feeds back five degrees of freedom motion parameters of the car body: lateral movement, vertical movement, side roll, pitching, and yaw, and outputs aerodynamic performance parameters and dynamic performance parameters simultaneously.

[0037] In the above embodiments, this simulation method can be further refined into the following specific steps:

[0038] (1) Establish a dynamic model of the vehicle system. A high-speed train dynamic model is established in the dynamics software, mainly considering: ① the mass, moment of inertia, center of gravity position, and geometric position of the vehicle body, bogie, and wheelsets; ② the vertical, lateral, and longitudinal stiffness, damping, and geometric position of the vehicle suspension system; ③ anti-roll torsion bars, lateral stops, etc.; ④ the nonlinear contact geometry and creep force between the wheel and rail; ⑤ because the focus is on the operational safety analysis under strong wind conditions, random track irregularities are not considered in this invention; ⑥ when the train passes through a curve, there may be unbalanced lateral acceleration, which has a significant impact on the train's safety indicators. Therefore, when analyzing the situation of the train encountering strong winds while passing through a curve, the influence of unbalanced acceleration and the direction of the incoming wind must also be considered.

[0039] (2) In the vehicle system dynamics model, by establishing a car body following marker point consistent with the aerodynamic simulation moment point of the train, the aerodynamic load of the train is applied to the dynamics model and the aerodynamic load data of the FMU model is exchanged. Since this invention is mainly aimed at the safe operation of high-speed trains in windy environments, the influence of aerodynamic drag is not considered. It is only necessary to establish 5 input functions such as lateral force, lift, rolling moment, pitching moment and yaw moment and corresponding 5 U-vectors. In addition, the aerodynamic and dynamic fluid-structure interaction simulation in windy environments is a continuous process and the load is a time-varying curve. Therefore, the loading function should use force element No. 93.

[0040] (3) In the vehicle system dynamics model, the FMU model exchange parameters in the fluid-structure interaction simulation process of high-speed train aerodynamics and dynamics performance under high wind conditions are further defined. These parameters include two types: one type is used to embed and parameterize the dynamic parameters in the train aerodynamic numerical simulation model; the other type is used to feed back the evolution of the train's dynamic behavior under aerodynamic action to the aerodynamic numerical model, thereby realizing the real-time update of the motion state of the car body and key components. The first type of parameter is realized by directly outputting variables in the dynamics model; the other type is dynamic time-varying parameter, which can only be realized by setting monitoring points on the car body and key components to obtain their motion characteristic parameters, such as velocity and angular acceleration, in real time.

[0041] (4) After the above vehicle system dynamics model is established, the model is output in FMU format.

[0042] (5) Establish a numerical simulation model of high-speed train aerodynamics under strong wind conditions. In CFD software, complete the numerical simulation settings for train aerodynamics, such as defining the computational domain boundary, mesh generation, and selecting the physical model. In this invention, the blockage ratio of aerodynamic performance numerical study under strong wind conditions is less than 5%, and the ratio of the windward side area to the leeward side area of ​​the computational domain is close to 1:2, and the ratio of the front end area to the rear end area is close to 1:3. The front end of the computational domain and the windward side of the car body are defined as the velocity inlet, and the rear end and the leeward side of the car body are defined as the pressure outlet. The reference pressure is 0 Pa. The ground surface is named "Ground," and the remaining surfaces are named "Symmetry." Because the multi-degree-of-freedom motion of the car body structure needs to be considered in the numerical simulation model of train aerodynamics, this invention adopts an overlapping mesh strategy. Furthermore, the bottom bogie region and the area around the car body are the regions with the most drastic flow field changes. Therefore, the mesh is refined at different distances from the train (this invention adopts a four-layer progressive refinement, with the mesh size increasing sequentially. First, local refinement is performed on the bottom region of the car body, ensuring that the refined area is longer than the train length; then, a three-layer progressive refinement is performed on the entire area around the train, with the ratio of the windward to leeward side dimensions of the refined area being approximately 1:2). The aspect ratio of the control mesh is kept to no more than 2:1 to ensure mesh quality. In addition, to more accurately capture the development of vortex structures on the car body surface, 10-15 boundary layer layers should be set near the car body surface.

[0043] (6) Two physical continuums are established in the numerical simulation model of train aerodynamics. One internal continuum physical model is used for the definition of the aerodynamic turbulence model. In order to prevent model stress loss and flow separation caused by mesh, the unsteady SST k−ω turbulence model and IDDES method are selected to simulate the flow field around the train. At the same time, the co-simulation protocol of FMI is defined in this physical continuum, and the influence of gravity is considered in the numerical study. The gravitational acceleration is 9.8 m / s2; the reference pressure is atmospheric pressure; and the initial conditions for solving are set, such as initial field velocity, turbulence intensity, turbulence velocity ratio, turbulence viscosity ratio, etc. The other external continuum physical model is defined as FMI, which is used to link the FMU model of vehicle dynamics. The FMI adopts version 2.0; and a new FMU region is created, which is also defined as FMI.

[0044] (7) Establish five aerodynamic and torque monitoring reports in the train aerodynamic numerical simulation model, and import the vehicle system dynamics model output from the FMU format file into the train aerodynamic numerical simulation model. Define the external link, with the external continuum being FMI, and establish a coupling negotiation based on the time step; the five aerodynamic and torque monitoring reports will be used as FMU input parameters.

[0045] (8) Define the multi-degree-of-freedom motion of key components such as car body and bogie in the train aerodynamic numerical simulation model; realize it through rotation and translation. This invention mainly considers the motion of five attitude degrees of freedom: lateral, vertical, side roll, nod and head. The real-time parameters of each attitude degree of freedom in the train aerodynamic numerical simulation model are obtained through the output in the FMU model. In this invention, the real-time exchange of data is realized through velocity and angular velocity.

[0046] (9) Specify the simulation time and time step, create a monitoring report of key parameters of the aerodynamic and dynamic performance of high-speed trains in windy environments, and realize the real-time synchronous output of train aerodynamic performance parameters (pressure, speed, aerodynamic load, etc.) and vehicle system dynamic parameters (5 degrees of freedom attitude parameters, suspension system force changes, displacement, speed, acceleration, wheel load reduction rate, overturning coefficient, derailment coefficient, etc.).

[0047] This application also provides a fluid-structure interaction numerical simulation system for high-speed train stability under wind shear, including a processor and a memory;

[0048] Memory, used to store computer programs;

[0049] When the processor executes the program stored in the memory, it implements any of the steps described in the numerical simulation method of fluid-structure interaction for high-speed train stability under wind shear.

[0050] The aforementioned numerical research system for the aerodynamic and dynamic performance of high-speed trains in high-wind environments can realize various embodiments of the aforementioned numerical research method for the aerodynamic and dynamic performance of high-speed trains in high-wind environments, and can achieve the same beneficial effects. It will not be elaborated here.

[0051] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A numerical simulation method for fluid-structure interaction of high-speed train stability under wind shear, characterized in that, include: S1. Define the mass and moment of inertia of the car body, bogie, and wheelset, the stiffness and damping of the suspension system, the nonlinear contact geometry of the wheel and rail, and the creep force as system dynamics data. Based on the system dynamics data, establish a high-speed train system dynamics model and determine the car body following marker points in the high-speed train system dynamics model. S2. Define five time-varying aerodynamic load input functions in the high-speed train system dynamics model: lateral force, lift, roll moment, pitching moment, and yaw moment. Load the time-varying aerodynamic load input functions through force element No. 93 and output the motion state parameters of the car body and key components to the high-speed train system dynamics model to obtain the high-speed train system dynamics model after loading the load. S3. Output the dynamic model of the high-speed train system after loading in S2 as an FMU format file; S4. Define the computational domain, the proportion of the windward and leeward sides, and the proportion of the front and rear ends of the vehicle as aerodynamic data. Based on the aerodynamic data, establish an aerodynamic model and determine the model's moment point in the aerodynamic model so that the position of the model's moment point is consistent with the vehicle's following marker point. S5. Establish two physical continuums in the aerodynamic model, namely the inner continuum and the outer continuum. The inner continuum simulates the flow field around the aerodynamic model, and the outer continuum is linked to the FMU format file of S3. S6. Numerical simulations are performed on the aerodynamic model and the system dynamics model. The aerodynamic model inputs five aerodynamic force and torque monitoring values ​​to the high-speed train system dynamics model. The dynamics model feeds back five degrees of freedom motion parameters of the car body: lateral movement, vertical movement, side roll, pitching, and yaw. Simultaneously, aerodynamic performance parameters and dynamic performance parameters are output.

2. The numerical simulation method for high-speed train stability under wind shear according to claim 1, characterized in that, In S1, the wheel-rail nonlinear contact geometry includes the effects of unbalanced lateral acceleration and incoming wind direction, and the vehicle body following markers are used to accurately apply aerodynamic loads to the dynamic model.

3. The numerical simulation method for high-speed train stability under wind shear according to claim 1, characterized in that, In S2, the motion state parameters include the linear velocity, angular velocity, linear acceleration, and angular acceleration of the vehicle body and bogie.

4. The numerical simulation method for high-speed train stability under wind shear according to claim 1, characterized in that, In S4, the blocking ratio of the computing domain is less than 5%, the ratio of the geometric regions on the windward and leeward sides of the vehicle body is 1:2, and the ratio of the front and rear ends of the vehicle body is 1:

3. The computational domain boundary is defined as follows: the front and windward sides of the aerodynamic model are the velocity inlet, the rear and leeward sides are the pressure outlet, the ground is the fixed wall, and the remaining surfaces are symmetry surfaces.

5. The numerical simulation method for high-speed train stability under wind shear according to claim 1, characterized in that, The S4 adopts a four-layer mesh densification strategy to handle the multi-degree-of-freedom motion of the vehicle body. The first layer densifies the bottom area of ​​the vehicle body and the range is greater than the length of the train. The remaining three layers are densified step by step around the train. The mesh length-to-width ratio is ≤2:

1. 10 to 15 boundary layers are set near the surface of the vehicle body.

6. The numerical simulation method for high-speed train stability under wind shear according to claim 1, characterized in that, In S5, the inner continuum is used for defining the aerodynamic turbulence model and simulating the effects of gravity. When simulating the effects of gravity, the gravitational acceleration is defined as 9.8 m / s², and the reference air pressure is one normal atmosphere. The outer continuum is used to link FMU format files, and the FMI interface is a 2.0 interface.

7. The numerical simulation method for high-speed train stability under wind shear according to claim 1, characterized in that, In S5, the FMI collaborative simulation protocol is a two-way data exchange channel. The two-way real-time data exchange channel includes: a first type of parameter and a second type of parameter. The first type of parameter is the dynamic state variable output to the aerodynamic numerical simulation model in real time, which is used for embedding and parameterized synchronous modeling of dynamic parameters in the train aerodynamic numerical simulation model. The second type of parameter is the motion characteristic parameter collected in real time through the monitoring points of the vehicle system component structure, which is used to realize the evolution of the vehicle dynamic behavior under aerodynamic action and feed it back to the aerodynamic numerical model.

8. The numerical simulation method for high-speed train stability under wind shear according to claim 1, characterized in that, In S6, the aerodynamic performance parameters include pressure distribution, flow field velocity, and aerodynamic load time history, while the dynamic performance parameters include suspension system force, wheel load reduction rate, derailment coefficient, and overturning coefficient.

9. A fluid-structure interaction numerical simulation system for high-speed train stability under wind shear, characterized in that, Including processor and memory; Memory, used to store computer programs; A processor, when executing a program stored in memory, implements the steps of the method described in any one of claims 1-8.

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