A method for numerical simulation of flow field distribution in continuous casting tundish

Abstract

The present application belongs to the technical field of continuous casting, and particularly relates to a method for numerical simulation of flow field distribution of a continuous casting tundish. Compared with a traditional method, the present application replaces entity modeling with a porous medium model, greatly simplifies the geometric construction of the solid region inside the calculation domain of the continuous casting tundish, enables the use of a structured grid, improves the solving precision and calculation efficiency, and provides an efficient and accurate solution for the numerical simulation of the continuous casting tundish.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of continuous casting, in particular to a method for numerical simulation of flow field distribution in a continuous casting tundish. BACKGROUND

[0002] The continuous casting process is one of the core links of modern steel production. The tundish, as an important component in the continuous casting system, plays a key role in buffering, uniformly distributing and removing inclusions of molten steel. In order to optimize the flow state of molten steel in the tundish, improve the cleanliness of molten steel and reduce metallurgical defects, structures such as dams, baffles or turbulence inhibitors are usually arranged inside the tundish to guide the flow path of molten steel and enhance the stability of the flow field. However, the complex geometry of these internal structures brings great challenges to the numerical simulation of the flow behavior of molten steel in the tundish.

[0003] In the traditional numerical simulation method, the internal structures such as dams and baffles are usually modeled by solid geometry, and are divided by unstructured grids. Although this method is intuitive, the modeling process is tedious and time-consuming due to the complex geometry of the dams and baffles, and often requires a large amount of pre-processing work. In addition, it is difficult to ensure the orthogonality and uniformity of the grid elements in the generation process of unstructured grids, and low-quality elements are easily generated, which affects the calculation accuracy. At the same time, the elements of unstructured grids are arranged irregularly, and the data structure is complex, which occupies a large amount of memory and slows down the addressing speed during calculation, resulting in low calculation efficiency. Especially in the process of solving the flow field, the solid regions of dams and baffles need to be refined, which further increases the calculation amount and reduces the simulation efficiency. In addition, the grid quality in the edge and transition regions of the dams is difficult to guarantee, which may lead to difficulties in convergence or large local numerical errors, affecting the reliability of the simulation results.

[0004] In the prior art, the numerical simulation of the internal structure of the tundish mainly adopts the method of direct geometry modeling combined with unstructured grids. Although this method can reflect the characteristics of the flow field to some extent, it is difficult to meet the demand for efficient and accurate simulation in industrial applications due to the complex modeling, low calculation efficiency and poor numerical stability. Especially when dealing with complex geometric structures, the traditional method has a large amount of pre-processing work, and the unstructured grid is difficult to guarantee the grid quality and calculation accuracy, which increases the technical challenges in metallurgical engineering applications. SUMMARY

[0005] To solve the problems existing in the prior art, the main purpose of the present application is to provide a method for numerical simulation of flow field distribution in a continuous casting tundish.

[0006] According to one aspect of the present application, the present application provides the following technical scheme:

[0007] A method for numerical simulation of flow field distribution in a continuous casting tundish, comprising the following steps:

[0008] S1. Based on the actual situation of the continuous casting tundish, construct a three-dimensional model of the tundish in the modeling software, ignoring internal structures such as retaining walls and dams, and then import the model into the mesh generation software for mesh generation.

[0009] S2. After introducing the mesh into the fluid simulation software, a porous media modeling method is adopted. The internal structural regions such as retaining walls and dams are marked by user-defined functions (UDFs), and the corresponding solid fraction and permeability parameters are set to construct the flow resistance model. The resistance source term opposite to the velocity direction is loaded into the momentum equation to simulate the influence of the internal structure on the fluid motion.

[0010] S3. Set up the simulation environment, including setting the gravity direction, material properties, and given boundary conditions and initial conditions;

[0011] S4. Enable physical models suitable for the three-phase flow behavior of the tundish, including multiphase flow models and fluid dynamics models, to improve simulation accuracy;

[0012] S5. Use the UDF compilation module of the simulation software to compile and load custom functions to achieve dynamic calling and linked simulation calculation;

[0013] S6. Perform flow field initialization, set parameters such as inlet velocity, phase interface, and initial distribution, and solve the fluid control equations using numerical methods to obtain the flow field distribution of molten steel in the tundish.

[0014] Specifically, the method described in this invention is used to achieve numerical simulation of the flow field distribution of fluid in the continuous casting tundish.

[0015] As a preferred embodiment of the numerical simulation method for the flow field distribution in a continuous casting tundish according to the present invention, in step S1, when importing the model into the mesh generation software for mesh generation, a structured mesh generation method is used to improve the simulation accuracy and computational stability.

[0016] As a preferred embodiment of the numerical simulation method for flow field distribution in a continuous casting tundish according to the present invention, in step S2, the DEFINE_ON_DEMAND function of the UDF is used to traverse all calculation cells, and the solid fraction of the internal structural regions such as retaining walls and dams is assigned according to the geometric conditions in the tundish.

[0017] In a preferred embodiment of the numerical simulation method for the flow field distribution in a continuous casting tundish according to the present invention, in step S2, based on permeability... The fluid velocity component generates a drag source term that is opposite to the velocity direction, and its expression is:

[0018]

[0019] in μ V is the fluid dynamic viscosity; V is the velocity component; As a regulatory factor, 0.1≤ ≤10; The specific formula for calculating the penetration rate is as follows:

[0020] Where C is a constant, and n≥1; The solid fraction of the unit.

[0021] To improve the adaptability of porous media models in the solid region and to adjust for the deviations of traditional models in terms of flow resistance, an adjustment coefficient is introduced. It is used to adjust the effect of the solid phase region on flow resistance, thereby simulating fluid motion in complex flow scenarios more accurately.

[0022] As a preferred embodiment of the numerical simulation method for the flow field distribution in a continuous casting tundish according to the present invention, in step S2, the resistance source term is implemented by the DEFINE_SOURCE function in the user-defined function (UDF), and the derivative term of the velocity component is implicitly processed to improve convergence.

[0023] As a preferred embodiment of the numerical simulation method for flow field distribution in a continuous casting tundish according to the present invention, in step S3, the gravity direction is set according to the actual requirements of the tundish structure layout and the steel flow path to accurately simulate the influence of gravity on the fluid; material properties include fluid density, viscosity, and surface tension to accurately describe fluid characteristics; boundary conditions are set according to calculation requirements, including inlet conditions, outlet conditions, and wall conditions to ensure that the flow in the computational domain conforms to the actual physical conditions; initial conditions include the initial velocity and pressure of the steel in the tundish to provide a reasonable initial flow state.

[0024] As a preferred embodiment of the numerical simulation method for the flow field distribution in a continuous casting tundish according to the present invention, in step S4, an appropriate fluid dynamics model is selected according to the calculation requirements, including laminar flow model, turbulent flow model, compressible fluid model, etc., to adapt to the simulation of different flow conditions.

[0025] As a preferred embodiment of the numerical simulation method for flow field distribution in continuous casting tundish according to the present invention, in step S4, an appropriate multiphase flow model is selected according to the calculation requirements, including the VOF (volume fraction of fluid) model, the Euler-Euler two-fluid model, or the Euler-Lagrange discrete phase model, to simulate the flow behavior between different phases, and to optimize the calculation accuracy by combining it with the turbulence model; and it is coupled with the selected fluid dynamics model to be applicable to multiphase flow simulation in different scenarios.

[0026] As a preferred embodiment of the numerical simulation method for the flow field distribution in a continuous casting tundish according to the present invention, in step S6, the initialization settings include the initial velocity, pressure and phase distribution of the flow field, and adaptive initial conditions can be set according to the selected flow model for single-phase flow, two-phase flow or multi-phase flow to optimize the calculation accuracy and stability.

[0027] As a preferred embodiment of the numerical simulation method for flow field distribution in continuous casting tundish according to the present invention, in step S6, the fluid control equation is discretized using the finite volume method (FVM), and a suitable numerical solution algorithm, including SIMPLE, PISO or SIMPLEC algorithm, is combined with the selected flow model to achieve efficient calculation of steady-state or transient flow and improve computational convergence.

[0028] The beneficial effects of this invention are as follows:

[0029] This invention proposes a method for numerical simulation of flow field distribution in a continuous casting tundish, comprising the following steps: S1, constructing a three-dimensional model of the tundish in modeling software based on the actual situation of the continuous casting tundish, ignoring internal structures such as retaining walls and dams, and then importing the model into mesh generation software for mesh generation; S2, importing the meshed model into fluid simulation software, using a porous media modeling method, marking internal structural regions such as retaining walls and dams through user-defined functions (UDFs), setting corresponding solid fraction and permeability parameters to construct a flow resistance model; and loading the resistance source term opposite to the velocity direction into the momentum equation. The simulation process involves several steps: S3, setting up the simulation environment, including defining gravity direction, material properties, boundary conditions, and initial conditions; S4, enabling physical models suitable for the three-phase flow behavior in the tundish, including multiphase flow models and fluid dynamics models, to improve simulation accuracy; S5, using the UDF compilation module of the simulation software to compile and load custom functions, enabling dynamic calling and linked simulation calculations; and S6, performing flow field initialization, setting parameters such as inlet velocity, phase interface, and initial distribution, and solving the fluid control equations using numerical methods to obtain the steel flow field distribution within the tundish. Compared to traditional methods, this invention replaces solid modeling with a porous medium model, significantly simplifying the geometric construction of the solid region within the computational domain. This allows for the use of structured meshes, improving solution accuracy and computational efficiency, and providing an efficient and accurate solution for the numerical simulation of continuous casting tundishes. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0031] Figure 1 This is a flowchart illustrating the method for numerical simulation of flow field distribution in continuous casting tundish according to the present invention.

[0032] Figure 2 This is a structural diagram of a dual-flow intermediate package provided by the present invention.

[0033] Figure 3 This is a geometric model diagram of the empty intermediate package provided by the present invention;

[0034] Figure 4 This is a schematic diagram of the structured mesh for the intermediate package empty package provided by the present invention;

[0035] Figure 5 A schematic diagram of the solid region defined for writing code for the intermediate empty packet provided by this invention;

[0036] Figure 6 The velocity cloud map on the longitudinal section of the continuous casting dual-flow tundish model simulated using traditional modeling methods provided by this invention;

[0037] Figure 7 The tundish longitudinal section velocity cloud map provided by the present invention.

[0038] The effects, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0039] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the 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.

[0040] According to one aspect of the present invention, the present invention provides the following technical solution:

[0041] like Figure 1 As shown, the present invention provides a method for numerical simulation of the flow field distribution in a continuous casting tundish, comprising the following steps:

[0042] S1. Based on the actual situation of the continuous casting tundish, construct a three-dimensional model of the tundish in the modeling software, ignoring internal structures such as retaining walls and dams, and then import the model into the mesh generation software for mesh generation.

[0043] S2. After introducing the mesh into the fluid simulation software, a porous media modeling method is adopted. The internal structural regions such as retaining walls and dams are marked by user-defined functions (UDFs), and the corresponding solid fraction and permeability parameters are set to construct the flow resistance model. The resistance source term opposite to the velocity direction is loaded into the momentum equation to simulate the influence of the internal structure on the fluid motion.

[0044] S3. Set up the simulation environment, including setting the gravity direction, material properties, and given boundary conditions and initial conditions;

[0045] S4. Enable physical models suitable for the three-phase flow behavior of the tundish, including multiphase flow models and fluid dynamics models, to improve simulation accuracy;

[0046] S5. Use the UDF compilation module of the simulation software to compile and load custom functions to achieve dynamic calling and linked simulation calculation;

[0047] S6. Perform flow field initialization, set parameters such as inlet velocity, phase interface, and initial distribution, and solve the fluid control equations using numerical methods to obtain the flow field distribution of molten steel in the tundish.

[0048] Specifically, the method for numerical simulation of the flow field distribution in the continuous casting tundish includes the following steps:

[0049] S1. Use the pre-processing software Design Modeler to draw a simplified intermediate package model with internal structure, and then import it into the mesh generation software ICEM for mesh generation; when drawing the model, only the structural parts outside the computational domain are considered.

[0050] S2. Import the mesh file into the fluid simulation software FLUENT. Using a porous media model, define the solid regions (dams, retaining walls, etc.) inside the intermediate package using a UDF (User-defined functions) program, and set key parameters such as solid fraction and permeability to control flow resistance. Based on the flow characteristics, construct a porous media resistance model, define and apply resistance source terms. These resistance source terms are calculated using fluid velocity and permeability and loaded into the momentum equation to simulate the influence of the solid regions on fluid motion. The UDF program includes the DEFINE_ON_DEMAND, DEFINE_SOURCE, and DEFINE_PROPERTY functions. The DEFINE_ON_DEMAND function iterates through all elements in the computational domain, dynamically marking the solid fraction based on geometric conditions. The DEFINE_SOURCE function adds porous media resistance terms to the momentum equation in the X / Y / Z directions to simulate the hindering effect of the solid structure on flow. In step S2, based on permeability... The fluid velocity component generates a drag source term that is opposite to the velocity direction, and its expression is: ,in, For fluid dynamic viscosity; V For velocity components; As a regulatory factor, 0.1≤ ≤10; The specific formula for calculating the penetration rate is as follows: Where C is a constant, and n≥1; The solid fraction is the unit. In step S2, the drag source term is implemented using the DEFINE_SOURCE function in a user-defined function (UDF), and the derivative term of the velocity component is implicitly processed to improve convergence.

[0051] S3. Set up the calculation environment, including adding gravity, setting materials, and giving boundary conditions and initial conditions.

[0052] S4. Enable the VOF multiphase flow model to simulate the flow of different phases, and combine it with the turbulence model to improve the calculation accuracy and stability;

[0053] S5. Compile the defined UDFs using the Compiled UDFs panel (user-defined function compilation interface) provided by the FLUENT software, and dynamically link them to the FLUENT solver.

[0054] S6. Initial parameters are set through flow field initialization, and the fluid control equations are solved using a numerical discretization method to obtain the flow field distribution in the continuous casting tundish. Inlet or outlet parameters are set to provide a clear quantitative description of the initial entry state of the fluid.

[0055] Selection of pressure-velocity coupling solution method: The SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) calculation method is adopted for pressure-velocity coupling solution. The SIMPLE method improves the stability and convergence speed of the solution by semi-implicitly discretizing the coupling relationship between pressure and velocity, thereby obtaining the flow field distribution results accurately and efficiently in the process of numerically discretizing and solving the fluid control equations.

[0056] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0057] Example 1

[0058] This embodiment selects a numerical simulation method for a dual-flow intermediate package in a factory, such as... Figure 2 As shown. The tundish inlet diameter is 75mm, and the outlet diameter is 20mm. The process includes the following steps:

[0059] S1, as Figure 3 As shown, the empty package model of the intermediate package (i.e., removing internal structures such as retaining walls and dams) is drawn using the pre-processing software Design Modeler, and then imported into the meshing software ICEM for structured mesh generation. See the mesh generation documentation. Figure 4 .

[0060] S2, import the mesh file into the fluid simulation software FLUENT. For example... Figure 5 As shown, user-defined functions are used to define the internal structures of the dual-stream intermediate package, such as retaining walls and dams.

[0061] S3 sets up the calculation environment, including adding gravity, setting materials, and specifying boundary and initial conditions. Specifically, gravity is added in the opposite direction of the Z-axis. Materials are set as molten steel, air, and slag. The inlet is set as a velocity inlet, the outlet as a pressure outlet, and the slag-air interface and molten steel-slag interface are set as internal boundaries.

[0062] S4 enables the use of the VOF three-phase flow model to simulate the three-phase flow of molten steel, slag layer and gas phase, and combines it with a turbulence model to improve calculation accuracy and stability; specifically, the turbulence model is the k-ε model.

[0063] S5 compiles the defined UDFs through the Compiled UDFs panel (user-defined function compilation interface) provided by the FLUENT software, so as to dynamically link them to the FLUENT solver;

[0064] S6. Initial parameters are set through flow field initialization, and the fluid control equations are solved using a numerical discretization method to obtain the flow field distribution. The specific steps are as follows:

[0065] Flow field initialization and phase setting: In the flow field initialization stage, the phase order is clearly defined as steel, air, and slag. The surface tension coefficients of each phase are set separately to accurately reflect the interaction characteristics between the phases.

[0066] Initial conditions for velocity inlet: At the velocity inlet, the inlet velocity direction is set to the opposite direction of the Z-axis, and the inlet velocity is set to provide a clear quantitative description of the initial entry state of the fluid.

[0067] Turbulence model parameter configuration:

[0068] At the velocity inlet: Set specific parameters for turbulence intensity and hydraulic diameter to simulate the turbulence characteristics of the fluid at the inlet, providing reasonable initial turbulence conditions for subsequent flow field calculations.

[0069] At the pressure outlet: Set the parameters for backflow turbulence intensity and backflow hydraulic diameter to accurately simulate the fluid backflow turbulence at the pressure outlet, ensuring the accuracy and reliability of the entire flow field calculation.

[0070] Selection of pressure-velocity coupling solution method: The SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) calculation method is used for pressure-velocity coupling solution.

[0071] Calculation results:

[0072] Depend on Figure 6 As can be seen, the velocity distribution map of the continuous casting dual-flow tundish model simulated by the traditional modeling method on the longitudinal section has poor quality because the traditional modeling method relies on unstructured mesh generation, so the mesh quality is lower than that of structured mesh, and the edges of the cloud map are prone to jaggedness, resulting in poor flow field cloud map quality.

[0073] Depend on Figure 7 As can be seen, the longitudinal section velocity cloud map of the impact zone of the dual-flow tundish using a structured mesh porous medium model effectively reflects the obstruction effect of internal solid regions such as the impact zone on the molten steel, greatly simplifies the modeling process, and produces a high-quality velocity field cloud map.

[0074] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for numerical simulation of flow field distribution in a continuous casting tundish, characterized in that, Includes the following steps: S1. Based on the actual situation of the continuous casting tundish, construct a three-dimensional model of the tundish in the modeling software, ignoring the internal structure including retaining walls and dams, and then import the model into the mesh generation software for mesh generation. S2. After introducing the mesh into the fluid simulation software, a porous media modeling method is adopted. The internal structural regions, including retaining walls and dams, are marked by user-defined functions. The corresponding solid fraction and permeability parameters are set to construct the flow resistance model. The resistance source term opposite to the velocity direction is loaded into the momentum equation to simulate the influence of the internal structure on the fluid motion. S3. Set up the simulation environment, including setting the gravity direction, material properties, and given boundary conditions and initial conditions; S4. Enable physical models suitable for the three-phase flow behavior of the tundish, including multiphase flow models and fluid dynamics models, to improve simulation accuracy; S5. Use the UDF compilation module of the simulation software to compile and load custom functions to achieve dynamic calling and linked simulation calculation; S6. Perform flow field initialization, set parameters including inlet velocity, phase interface, and initial distribution, and solve the fluid control equations using numerical methods to obtain the flow field distribution of molten steel in the tundish.

2. The method for numerical simulation of flow field distribution in continuous casting tundish according to claim 1, characterized in that, In step S1, a structured partitioning method is used to partition the grid.

3. The method for numerical simulation of flow field distribution in continuous casting tundish according to claim 2, characterized in that, In step S2, the DEFINE_ON_DEMAND function of the UDF is used to traverse all computational units and assign solid phase fractions to the internal structural regions, including retaining walls and dams, according to the geometric conditions within the intermediate package.

4. The method for numerical simulation of flow field distribution in continuous casting tundish according to claim 1, characterized in that, In step S2, based on the penetration rate The fluid velocity component generates a drag source term that is opposite to the velocity direction, and its expression is: in μ V is the fluid dynamic viscosity; V is the velocity component; As a regulatory factor, 0.1≤ ≤10; The specific formula for calculating the penetration rate is as follows: Where C is a constant, and n≥1; The solid fraction of the unit.

5. The method for numerical simulation of flow field distribution in continuous casting tundish according to claim 1, characterized in that, In step S2, the resistance source term is implemented through the DEFINE_SOURCE function in the user-defined function, and the derivative term of the velocity component is implicitly processed to improve convergence.

6. The method for numerical simulation of flow field distribution in continuous casting tundish according to claim 1, characterized in that, In step S3, the direction of gravity is set according to the actual requirements of the tundish structure layout and the flow path of the molten steel; the material properties include fluid density, viscosity, and surface tension; the boundary conditions are set according to the calculation requirements, including inlet conditions, outlet conditions, and wall conditions; the initial conditions include the initial velocity and pressure of the molten steel in the tundish.

7. The method for numerical simulation of flow field distribution in continuous casting tundish according to claim 1, characterized in that, In step S4, the fluid dynamics model selected according to the calculation requirements includes laminar flow model, turbulent flow model, and compressible fluid model.

8. The method for numerical simulation of flow field distribution in continuous casting tundish according to claim 1, characterized in that, In step S4, the multiphase flow model selected according to the calculation requirements includes the VOF model, the Euler-Euler two-fluid model, or the Euler-Lagrange discrete phase model, and is used in conjunction with the selected fluid dynamics model to be applicable to multiphase flow simulation in different scenarios.

9. The method for numerical simulation of flow field distribution in continuous casting tundish according to claim 1, characterized in that, In step S6, the initialization settings include the initial velocity, pressure, and phase distribution of the flow field.

10. The method for numerical simulation of flow field distribution in continuous casting tundish according to claim 1, characterized in that, In step S6, the fluid control equations are discretized using the finite volume method, and a suitable numerical solution algorithm, including SIMPLE, PISO, or SIMPLEC, is combined with the selected flow model.

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