Simulation method for particle motion and interaction behavior within continuous casting mold

Abstract

The present invention relates to the technical field of steel metallurgy process simulation, and specifically relates to a simulation method for particle motion and interaction behavior within a continuous casting mold. The simulation method comprises the following steps: acquiring mold parameters and establishing a model; performing fluid domain volume extraction and structured mesh division on the model; importing the mesh model into simulation software and performing iterative solution; establishing injection points for argon bubbles and inclusions within the mold, compiling and calculating the flotation removal of argon bubbles and inclusions at a steel-slag interface, the capture thereof at a solidification front, and collision-aggregation, and performing coupled computation; and post-processing the simulation results to obtain the flow field, temperature field, solidified-shell distribution, and discrete-phase motion behavior within the mold at different time points. The method of the present invention enables analysis of the motion and interactions of discrete-phase particles such as argon bubbles and inclusions within the mold, thereby accurately predicting the distribution of the particles in the molten steel and the solidified shell.

Description

Simulation method for particle motion and interaction behavior in continuous casting crystallizer TECHNICAL FIELD

[0001] The present application belongs to the technical field of simulation of steel metallurgical process, and particularly relates to a simulation method for particle motion and interaction behavior in continuous casting crystallizer. BACKGROUND

[0002] The crystallizer is the core equipment of the steel continuous casting process, and bears the important function of solidifying the molten steel into a shell. There are complex physical and chemical phenomena such as turbulent flow, heat transfer, solute diffusion and discrete phase particle motion in the continuous casting crystallizer, which is a complex system in the state of multi-physical field-multiphase flow coupling. In order to avoid the clogging of the nozzle and improve the cleanliness of the molten steel, argon blowing is usually carried out at the submerged nozzle of the crystallizer to prevent the aggregation of inclusions at the nozzle wall and to promote the floating and removal of inclusion particles in the crystallizer. Therefore, it is crucial to analyze the instantaneous motion, interaction and capture behavior of the argon bubbles, inclusions and other discrete phase particles in the molten steel in the crystallizer to improve the cleanliness of the molten steel and enhance the production stability.

[0003] Due to the high temperature in the crystallizer, it is difficult to directly observe the motion behavior of argon bubbles and inclusions in industrial fields. Therefore, numerical simulation research has become an effective method to study the motion behavior and interaction of the two. Researchers have proposed a method to calculate the collision behavior of argon bubbles and inclusions based on numerical simulation technology, and analyzed the removal effect in specific metallurgical reactors. For example, the article Numerical investigation on particles removal by bubble flotation in swirling flow (Cui H, Li T, Zhu Y, et al. Numerical investigation on particles removal by bubble flotation in swirling flow[J]. Journal of Iron and Steel Research International, 2022, 29(6): 961-972.) proposed a method to calculate the collision behavior of argon bubbles and inclusions based on their position, motion speed and time step, and determined whether the two collided by analyzing the position of each argon bubble and inclusion at the end of the time step in the simulation calculation. The articles Numerical Simulation of Inclusion Removal by Bubble Injection in the Submerged Nozzle With Swirling Flow (Xin Z, Cui H, Li T, et al. Metallurgical and Materials Transactions B, 2022, 53(4): 2570-2586.) and Simulation of Inclusion Removal in Bottom-blowing Ladle with Tracking the Collision of Inclusions and Bubbles in Transient Time Steps (Liu K, Zhang L, Cui H, et al. ISIJ International, 2023, 63(10): 1677-1686.) respectively studied the effect of argon blowing process on inclusion removal in continuous casting tundish and ladle based on this method.

[0004] However, the above method is not suitable for studying the motion behavior and interaction of argon bubbles and inclusions in the continuous casting crystallizer. First, the existing method only considers the interaction of argon bubbles and inclusions and its removal at the steel slag interface, without considering the capture process at the crystallizer solidification front; second, the existing method needs to solve the positions and velocities of a large number of argon bubbles and inclusions iteratively when determining the collision of argon bubbles and inclusions, which is difficult to calculate and time-consuming to solve; finally, the existing method determines the collision based on the positions of argon bubbles and inclusions at the end of each time step, ignoring the collision behavior that may occur within a single time step, resulting in errors in the final removal rate. SUMMARY

[0005] In view of the above technical problems existing in the prior art, the present application provides a simulation method for the motion and interaction behavior of particles in a continuous casting crystallizer, which aims to solve the technical problems that the existing method cannot solve the capture behavior of discrete phase particles such as argon bubbles and inclusions in the crystallizer molten steel at the solidification front, and the calculation of argon bubble and inclusion collision is time-consuming and low in accuracy.

[0006] In order to achieve the above technical purpose, the present application provides the following technical scheme:

[0007] A simulation method for the motion and interaction behavior of particles in a continuous casting crystallizer, comprising the following steps:

[0008] S1: Obtain the geometric structure parameters of the continuous casting crystallizer in actual production, and establish a three-dimensional geometric model of the continuous casting crystallizer by using Spaceclaim three-dimensional modeling software;

[0009] S2: Extract the volume of the fluid domain of the continuous casting crystallizer three-dimensional geometric model by using Spaceclaim three-dimensional modeling software, and divide the structure grid by using ICEM software to obtain the grid model of the molten steel fluid domain in the crystallizer;

[0010] S3: Import the grid model of the molten steel fluid domain in the crystallizer into ANSYS Fluent simulation software, select the calculation model and solving algorithm, define the physical property parameters and boundary conditions, and perform initialization operation and iterative solving to obtain the molten steel flow field, temperature field and solidification shell distribution in the crystallizer under the action of electromagnetic braking;

[0011] S4: Establish the injection point of argon bubbles and inclusions in the crystallizer, call the UDF program to compile and calculate the floating removal behavior of argon bubbles and inclusions at the steel slag interface, the capture behavior of argon bubbles and inclusions at the solidification front, and the collision and aggregation behavior of argon bubbles-inclusions to obtain the motion behavior of argon bubbles and inclusions in the crystallizer;

[0012] S5: coupling the flow field, temperature field and solidified shell distribution of the molten steel in the crystallizer under the electromagnetic braking action obtained in step S3 with the motion behavior of the argon bubbles and inclusions in the crystallizer obtained in step S4, to obtain a simulation result of the multi-physical field-multiphase flow of the crystallizer considering the electromagnetic braking action and the collision and aggregation behavior of the argon bubbles-inclusions;

[0013] S6: performing a post-processing operation on the simulation result of the multi-physical field-multiphase flow of the crystallizer considering the electromagnetic braking action and the collision and aggregation behavior of the argon bubbles-inclusions, to obtain a simulation result of the flow field, temperature field, solidified shell distribution and motion behavior of the dispersed phase in the crystallizer at different times.

[0014] Further, in step S1, the geometric structure parameters of the continuous casting crystallizer include the width, height and thickness of the crystallizer, and the diameter of the submerged nozzle, the outlet height, the outlet width and the outlet position.

[0015] Further, in step S2, in the process of extracting the fluid domain volume and structuring the grid of the three-dimensional geometric model of the continuous casting crystallizer, a local boundary layer grid encryption operation is performed on the region near the wall surface of the fluid domain to accurately calculate the growth of the solidified shell.

[0016] The encryption operation specifically includes: using a hexahedral structured grid to divide the region near the wall surface of the fluid domain, increasing the grid nodes in the range of 10-15 mm from the wall surface, the grid thickness after encryption is in the range of 0.5-1.5 mm, the overall grid quality is in the range of 0.6-1.0, the maximum aspect ratio of a single grid is less than 10, and the total number of grids is greater than 1 million.

[0017] Further, step S3 specifically includes:

[0018] S31: selecting a calculation model and a solving algorithm:

[0019] In the ANSYS Fluent software, a large eddy simulation model (LES) is selected to solve the turbulent motion of the molten steel in the crystallizer, a volume of fluid (VOF) model is selected to solve the fluctuation behavior of the molten steel-slag interface, an energy conservation equation is enabled to solve the heat transfer behavior of the molten steel in the crystallizer, a solidification and melting model (Solidification and Melting Model) is selected to solve the solidification and melting behavior of the molten steel and define the shell movement speed according to the withdrawal rate, and a magnetohydrodynamic (MHD) model is selected to solve the influence of the electromagnetic field on the flow behavior of the molten steel;

[0020] The coupled algorithm is used for pressure-velocity coupling, the staggered pressure algorithm (PRESTO! algorithm) is used for spatial discretization of pressure, the bounded central difference format algorithm (Bounded Central Differencing) is used for spatial discretization of momentum, the second-order upwind and first-order upwind formats are used for discretization of energy equation and magnetohydrodynamic equation respectively; the bounded second-order implicit (Bounded Second Order Implicit) transient formula is used for solving, so as to ensure the stability of calculation;

[0021] Wherein, the PRESTO! algorithm (PREssure STaggering Option, PRESTO!) is a staggered pressure algorithm, which is used for discretization of pressure term, so that the pressure can better satisfy the momentum equation and continuity equation at the same time; the PRESTO! algorithm is a regular option in the Fluent software, which is a regular technology.

[0022] S32: defining physical parameters and boundary conditions: setting the density, viscosity, thermal conductivity, specific heat capacity, latent heat, liquidus temperature, solidus temperature, electrical conductivity and magnetic permeability parameters of the molten steel and the protective slag in the ANSYS Fluent software, setting the density of argon bubbles and inclusions;

[0023] The inlet of the submerged nozzle is set as a velocity inlet boundary condition, the specific inlet velocity value is calculated in combination with the withdrawal rate and the cross-sectional size, the inlet temperature value is set as the pouring temperature of the molten steel, and the discrete phase boundary condition type at the inlet is set as rebound; the top surface of the crystallizer is set as an adiabatic slip wall surface boundary condition, the discrete phase boundary condition type of the top surface of the crystallizer is set as escape; the bottom surface of the crystallizer is set as a fluid outflow outlet boundary condition, the discrete phase boundary condition type of the bottom surface of the crystallizer is set as escape; the side wall surface of the crystallizer is set as a no-slip wall surface boundary condition, and the heat exchange type is convective heat exchange, and the convective heat exchange coefficient is determined according to the empirical formula of the heat flux density of the continuous casting crystallizer, and the formula is as follows:

[0024] ;

[0025] In the formula, h is the convective heat exchange coefficient of the side wall surface of the crystallizer, A and B are empirical constants calculated according to the water volume of the crystallizer, A can be taken as an empirical value of 2680000, B can be taken as an empirical value of 355000, y is the coordinate in the direction of withdrawing the blank, v is the withdrawal speed, T and T ref are the wall surface temperature and the reference temperature respectively, and the reference temperature is the environmental temperature of the crystallizer; the discrete phase boundary condition type of the side wall surface of the crystallizer is set as escape;

[0026] S33: setting the solving parameters after initializing the flow field and temperature field of the calculation domain, and performing iterative solving.

[0027] Further, in step S32, the inlet velocity value is calculated in combination with the withdrawal rate and the cross-sectional size, specifically:

[0028] Inlet velocity = (withdrawal rate × cross-sectional area of crystallizer) / inlet area of nozzle.

[0029] Further, in step S4, the following steps are specifically included:

[0030] S41: Obtain the inclusion radius R p , the injection points of the argon bubbles and the inclusions are established by the face injection function in ANSYS Fluent, the submerged nozzle inlet is selected as the injection point, and the sizes of the argon bubbles and the inclusions are set; the radius R b of the argon bubbles is 1-5×10 -3 m;

[0031] S42: The floating removal behavior of the argon bubbles and the inclusions at the steel-slag interface and the capture behavior of the argon bubbles and the inclusions at the solidification front are calculated by calling the DEFINE_DPM_SCALAR_UPDATE macro through the UDF program, when the argon bubbles or the inclusions move to the protection slag phase volume fraction or the solid phase rate reaches the separation condition, the corresponding argon bubble or inclusion particle is removed from the calculation domain, that is, the first remaining argon bubbles and the first remaining inclusions are obtained;

[0032] S43: The collision and aggregation behavior of the first remaining argon bubbles and the first remaining inclusions obtained in step S42 are calculated by calling the EXECUTE_AT_END macro, the position coordinates x b , y b , z b and the velocity components v b,x , v b,y , v b,z of the first remaining argon bubbles, and the position coordinates x p , y p , z p and the velocity components v p,x , v p,y , v p,z of the first remaining inclusions at the current time are obtained, and the calculation time step t is set, the potential collision zone radius R c is calculated based on the velocity components of the first remaining argon bubbles and the time step, as follows:

[0033] ;

[0034] The inclusions whose distance from the argon bubbles is less than R c are defined as the first potential collision inclusions;

[0035] S44: According to the vector composition method, the velocity included angle θ between all first residual argon bubbles and first potential collision inclusions is calculated, and the first potential collision inclusions with the included angle within the range of the collision angle are screened out, which are defined as second potential collision inclusions.

[0036] S45: The time step t is equally divided into n parts, and the position coordinates of the first residual argon bubbles and the second potential collision inclusions in the i-th (1≤i≤n) state within t seconds are calculated according to the position coordinates and the velocity in each direction of the first residual argon bubbles and the second potential collision inclusions, and the calculation formula is as follows:

[0037] ;

[0038] ;

[0039] ;

[0040] ;

[0041] ;

[0042] ;

[0043] wherein x i , y i and z b are the position coordinates of the first residual argon bubbles in the i-th state within t seconds, and x p , y p and z b are the position coordinates of the second potential collision inclusions in the i-th state within t seconds.

[0044] S46: The position coordinates of each argon bubble and inclusion obtained in step S45 are used to calculate the i-th state, i.e. the distance D -3 between the spherical centers of the first residual argon bubbles and the second potential collision inclusions at i / n moment, as follows:

[0045] ;

[0046] It is defined that when the distance D b between the spherical centers of the inclusion and the argon bubble is less than the sum of the radii (R slag +R solid ) of the two, the corresponding inclusion collides with the bubble, i.e. the inclusion to be removed, and the inclusion to be removed is removed from the first residual inclusion to obtain the second residual inclusion, and the second residual inclusion and the first residual argon bubble have a motion behavior, i.e. the motion behavior of the argon bubbles and inclusions in the crystallizer is obtained.

[0047] Further, the inclusion radius R obtained in step S41 p Specifically, the inclusion size is determined by sampling the casting blank and observing under an electron microscope; the radius R of the argon bubble is obtained by water model physical experiment test and reference data. b The radius R of the argon bubble is 1-5*10 -3 m. R b The size range of the bubble can be obtained by water model physical experiment test and reference data, which is a conventional technique.

[0048] Further, the separation condition in step S42 is specifically that the protective slag phase volume fraction f slag ≥ 0.5 or the solid phase rate f solid ≥ 0.7.

[0049] Further, in step S44, the collidable angle range is -90 to 90°.

[0050] The present application has the following beneficial effects:

[0051] The present application provides a simulation method for the movement and interaction behavior of particles in a continuous casting crystallizer. By considering the capture behavior of argon bubbles and inclusions at the steel slag interface and the solidification front in the crystallizer and the argon bubble-inclusion collision behavior, the movement behavior of argon bubbles and inclusions in the molten steel during continuous casting is simulated. The obtained argon bubble and inclusion distribution is more consistent with the actual continuous casting process, and the influence of key process parameters such as submerged entry nozzle structure, casting speed, electromagnetic braking parameters on the movement and distribution of discrete phase particles in the crystallizer can be obtained. The results have important guiding significance for precise control of actual continuous casting parameters, design optimization of continuous casting equipment and quality improvement and efficiency increase of continuous casting production line. BRIEF DESCRIPTION OF DRAWINGS

[0052] Fig. 1a is a geometric model of the crystallizer established in the embodiment of the present application.

[0053] Fig. 1b is a schematic diagram of the structured grid divided in the embodiment of the present application.

[0054] Fig. 1c is a schematic diagram of the structured grid divided in the embodiment of the present application.

[0055] Fig. 2 is a schematic diagram of the position and collision state of argon bubbles and inclusions at each intermediate time after the time step is divided into four equal parts.

[0056] Fig. 3 is a schematic diagram of the inclusion quantity statistics and casting blank sampling position involved in the verification of the simulation calculation results based on electrolysis experiments in the embodiment of the present application.

[0057] Fig. 4 is a comparison diagram of inclusion content at different positions in the width direction of the casting blank obtained by simulation calculation and electrolysis experiments under the working condition of the embodiment of the present application.

[0058] Figure 5 is a schematic diagram of the angle between the first remaining argon bubble and the first potential collision inclusion. DETAILED DESCRIPTION

[0059] The technical solutions of the present application will be further described below in combination with specific embodiments and the accompanying drawings.

[0060] The present embodiment provides a simulation method for the movement and interaction behavior of particles in a continuous casting crystallizer, specifically comprising the following steps:

[0061] S1: According to the thin slab continuous casting crystallizer and its matching multi-hole submerged nozzle provided by a steel plant, a geometric model of the inside of the crystallizer and the nozzle is constructed using ANSYS Spaceclaim three-dimensional modeling software, as shown in Figure 1a, wherein the width of the crystallizer is 1250 mm, the thickness is 110 mm, the height is 1200 mm, the upper part of the submerged nozzle is cylindrical, the inlet diameter is 125 mm, the bottom is flat and divided into a wide surface of the nozzle and a narrow surface of the nozzle, and there are four outlets, two lateral outlets are located on the narrow surfaces of the nozzle on both sides, 20 mm away from the bottom surface of the nozzle, and 30 mm away from the wide surfaces of the nozzle on both sides, the outlet face is rectangular, the length is 80 mm, and the width is 50 mm, two main outlets are located on the bottom surface of the nozzle, 55 mm away from the narrow surfaces of the nozzle on both sides, and 30 mm away from the wide surfaces of the nozzle on both sides, the outlet face is rectangular, the length is 120 mm, and the width is 50 mm, and it is saved as a.scdoc format file;

[0062] S2: The calculation domain for solving the flow of molten steel in the crystallizer and the nozzle is extracted based on Boolean operation using Spaceclaim software, and the extracted calculation domain is imported into ICEM mesh division software, first the boundary surfaces are defined and named, then the Vertex, Edge and Face are associated and the Block is divided, when dividing the mesh, the grid nodes are increased in the range of 15 mm from the wall surface of the calculation domain, the local boundary layer mesh is encrypted for accurate calculation of the growth of the solidified shell, the grid thickness in the encryption area is 0.5 mm, the overall grid quality is higher than 0.6, the maximum aspect ratio of a single grid is less than 10, and the total number of grids is 1.3 million, and it is exported as a.msh format file, as shown in Figures 1b and 1c;

[0063] S3: The exported.msh format crystallizer mesh file is imported into ANSYS Fluent for solving setting;

[0064] According to the specific flow conditions of the molten steel in the crystallizer, the LES turbulence model is selected in the ANSYS Fluent software to solve the turbulent motion of the molten steel in the crystallizer, the VOF model is selected to solve the fluctuation behavior of the molten steel-protective slag interface, the energy conservation equation is enabled to solve the heat transfer behavior of the molten steel in the crystallizer, the Solidification and Melting model is selected to solve the solidification and melting behavior of the molten steel, and the shell movement speed is set to 0.1 m / s according to the pulling speed, and the MHD model is selected to solve the influence of the electromagnetic field on the flow behavior of the molten steel. The coupled algorithm is used for pressure-velocity coupling, the PRESTO! algorithm is used for spatial discretization of pressure, the Bounded Central Differencing algorithm is used for spatial discretization of momentum, and the energy equation and the MHD equation are discretized by the second-order upwind and first-order upwind formats, respectively. In addition, the Bounded Second Order Implicit transient formula is used for solving to ensure the stability of the calculation.

[0065] In the ANSYS Fluent software, the physical property parameters of the continuous phase molten steel, the protective slag and the discrete phase argon bubbles and inclusions are set, wherein the molten steel is the continuous phase main phase, the density is 7020 kg / m 3 , the viscosity is 0.0053 Pa·s, the thermal conductivity is 27 W / (m·K), the specific heat capacity is 720 J / (kg·K), the solidification latent heat is 275000 J / kg, the liquidus temperature is 1794 K, the solidus temperature is 1749 K, the electrical conductivity is 714000 S / m, and the magnetic permeability is 1.257×10 -6 H / m; the protective slag is the continuous phase secondary phase, the density is 3000 kg / m 3 , the viscosity is 0.259 Pa·s, the thermal conductivity is 2 W / (m·K), the specific heat capacity is 830 J / (kg·K), the liquidus temperature is 1573 K, the solidus temperature is 1352 K, the electrical conductivity is 714000 S / m, and the magnetic permeability is 1.257×10 -6 H / m; the argon bubble is the discrete phase, the density is 1.6228 kg / m 3 ; the inclusion is the discrete phase, the density is 2700 kg / m 3 .

[0066] Boundary conditions were set in ANSYS Fluent software, the entrance of submerged nozzle was set as velocity inlet boundary condition, the inlet velocity was calculated as 1.0852 m / s according to the actual velocity value 6 m / min, the inlet steel liquid temperature was obtained based on the actual pouring temperature, and the discrete phase boundary condition type at the entrance was set as Reflect; the top surface of the crystallizer was set as adiabatic slip wall boundary condition, the discrete phase boundary condition type at the top surface of the crystallizer was set as Escape; the bottom surface of the crystallizer was set as Outflow boundary condition, the discrete phase boundary condition type at the bottom surface of the crystallizer was set as Escape; the side wall surface of the crystallizer was set as no-slip wall boundary condition, and the heat exchange type was convective heat exchange, and the convective heat exchange coefficient was determined according to the empirical formula of heat flux density of continuous casting crystallizer, and the formula was as follows:

[0067] ;

[0068] wherein h is the side wall surface convective heat exchange coefficient, A and B are both empirical constants calculated according to the water volume of the crystallizer, A is 2680000, B is 355000, y is the coordinate in the direction of drawing, v is the drawing speed, 6 m / min, T and T ref are the wall surface temperature and reference temperature respectively, and the reference temperature is the environmental temperature of the crystallizer, and is set as 300 K;

[0069] After initializing the flow field and temperature field of the calculation domain, the solving parameters were set, the initial velocity of the calculation domain was set as 0 m / s, the initial temperature was set as 1826 K, the solving time step t was set as 1×10 -3 s, 200 steps were iterated in each time step, and iterative calculation was performed;

[0070] S4: the radius R p of the inclusion was 2.5×10 -5 m, the entrance of the submerged nozzle was set as the injection point of the argon bubble and the inclusion through the Surface injection function in the DPM model of ANSYS Fluent software, and the radius R b of the argon bubble was 1×10 -3 m based on the actual pouring process;

[0071] The floating removal behavior of the argon bubble and the inclusion at the steel slag interface and the capture behavior at the solidification front were calculated through the UDF program calling the DEFINE_DPM_SCALAR_UPDATE macro, and it was set that when the argon bubble or the inclusion moved to the protective slag phase volume fraction f slag was greater than 0.5 or the solid phase rate f solidWhen the area is greater than 0.7, the corresponding argon bubble or inclusion particle is removed from the calculation domain to obtain first remaining argon bubbles and first remaining inclusions;

[0072] The collision aggregation behavior of argon bubbles-inclusions is calculated by calling the EXECUTE_AT_END macro, and the position coordinates x b , y b , z b of the first remaining argon bubbles in the calculation domain, the velocity components v b,x , v b,y , v b,z in each direction, the position coordinates x p , y p , z p of the first remaining inclusions, and the velocity components v p,x , v p,y , v p,z in each direction are obtained, and the calculation time step t=1×10 -3 s is set. The potential collision area radius Rc is calculated based on the velocity of the first remaining argon bubbles and the time step, as shown in the following formula:

[0073]

[0074] The inclusion particles with a distance less than R c from the argon bubbles are defined as the first potential collision inclusions.

[0075] According to the vector composition method, as shown in FIG. 5, the speed angle θ between all first remaining argon bubbles and first potential collision inclusions is calculated in the direction of the speed v b of the first remaining argon bubbles as the reference, and the first potential collision inclusions with an angle within the range of the collision angle are screened out and defined as the second potential collision inclusions.

[0076] Specifically, in the present application, the direction of the speed V b of the first remaining argon bubbles is defined as 0°, and the angle is positive when rotating clockwise and negative when rotating counterclockwise.

[0077] In the present embodiment, the first potential collision inclusions (in FIG. 5, V p is the speed of the first potential collision inclusions) with an angle within the range of -90 to 90° from the first remaining argon bubbles are defined as the second potential collision inclusions.

[0078] The time step t=1×10 -3 ​s, the position coordinates of the argon bubble and the inclusions in the i-th (1≤i≤4) state in the time step are calculated according to the first remaining argon bubble, the position coordinates of the second potential collision inclusions and the velocity in each direction, as shown in FIG. 2, and the calculation formula is as follows:

[0079] (1);

[0080] (2);

[0081] (3);

[0082] (4);

[0083] (5);

[0084] (6);

[0085] According to the position coordinates of each argon bubble and inclusion at the time of 0.25×10 -3 s, 0.5×10 -3 s, 0.75×10 -3 s and 1×10 -3 s obtained by the foregoing calculation, the center-to-center distances D1, D2, D3 and D4 of each inclusion and argon bubble at the time of 0.25×10 -3 s, 0.5×10 -3 s, 0.75×10 -3 s and 1×10 -3 s are calculated in sequence according to formulas (7) to (10). After the calculation is completed, the center-to-center distances D1, D2, D3 and D4 are compared with the radii of the inclusions and the argon bubble. If any one of D1, D2, D3 and D4 is less than 2.05×10 -3 m, it is considered that the inclusion and the bubble have collided, so that the inclusion to be removed is removed from the first remaining inclusion to obtain the second remaining inclusion, and the second remaining inclusion and the first remaining argon bubble have the motion behavior.

[0086] (7);

[0087] (8);

[0088] (9);

[0089] (10);

[0090] S5: coupling the flow field, temperature field and solidification shell distribution of the molten steel in the crystallizer under electromagnetic braking obtained in step S3 with the movement behavior of the argon bubbles and the movement behavior of the inclusions in the crystallizer obtained in step S4, saving the calculation results every 0.1 s time interval, and exporting.cas and.dat format files;

[0091] S6: importing the.cas and.dat format files exported in S5 into the post-processing software Tecplot for post-processing operation, extracting the center profile of the wide surface of the crystallizer, and extracting the positions of the discrete-phase argon bubbles and inclusions under the collision condition, obtaining the distribution of the flow field, temperature field and discrete-phase argon bubbles and inclusions in the crystallizer under the conditions of electromagnetic braking and argon blowing at 10 s, 20 s, 30 s, 40 s and 50 s, and exporting the post-processing results in.tif format.

[0092] After the calculation is completed, the calculation results at 50 s are taken, the outlet surface of the crystallizer is taken as the bottom surface, 50 mm*50 mm*50 mm cubic regions are respectively defined at the center position, 1 / 4 position and edge position of the outlet surface, the UDF program is called to count the number of inclusions falling in the above three statistical regions according to the second residual inclusion coordinate data, and the proportion of the number of inclusions at each position is calculated, and the statistical results are shown in the dashed line part of FIG. 4 as the calculation value.

[0093] Verification experiment

[0094] Under the same working condition as the specific embodiment of the present application, the molten steel is poured to obtain a casting blank, and then 50 mm*50 mm*50 mm samples are taken at the center position of the casting blank, the 1 / 4 position of the casting blank and the narrow surface position of the casting blank for bulk electrolysis experiment, the inclusions electrolyzed are washed and weighed, and the weight proportion of the inclusions at each position is calculated, as shown in the solid line part of FIG. 3 as the experimental value.

[0095] According to the comparison of the calculation value and the experimental value in FIG. 3, the statistical deviation of the calculation value and the experimental value is within 5%, which shows that the technical scheme of the present application can well simulate the collision behavior of the bubbles and inclusions in the crystallizer.

[0096] Finally, it should be noted that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. For ordinary skilled persons in the art, the aforementioned technical solutions can still be modified or deformed and improved, which are all within the protection scope of the present application.

Claims

1. A method of simulating the behavior of particles motion and interaction in a continuous casting mold, characterized in that, The method comprises the following steps: S1: obtaining geometric structure parameters of a continuous casting crystallizer in actual production, and establishing a three-dimensional geometric model of the continuous casting crystallizer; S2: performing fluid domain volume extraction and structured grid division on the three-dimensional geometric model of the continuous casting crystallizer to obtain a grid model of a molten steel fluid domain in the crystallizer; S3: importing the grid model of the molten steel fluid domain in the crystallizer into simulation software, selecting a calculation model and a solving algorithm, defining physical property parameters and boundary conditions, and performing iterative solving after initialization to obtain a molten steel flow field, a temperature field and a solidified shell distribution in the crystallizer under the action of electromagnetic braking; S4: establishing an argon bubble and inclusion injection point in the crystallizer, compiling and calculating the floating removal behavior of argon bubbles and inclusions at a molten steel-slag interface, the capturing behavior of argon bubbles and inclusions at a solidification front and the collision and aggregation behavior of argon bubbles-inclusions to obtain the motion behavior of argon bubbles and inclusions in the crystallizer; S5: coupling calculation of the molten steel flow field, the temperature field and the solidified shell distribution in the crystallizer under the action of electromagnetic braking obtained in step S3 and the motion behavior of argon bubbles and inclusions in the crystallizer obtained in step S4 to obtain a simulation result of a multi-physical field-multiphase flow of the crystallizer considering the action of electromagnetic braking and the collision and aggregation behavior of argon bubbles-inclusions; S6: performing post-processing on the simulation result of the multi-physical field-multiphase flow of the crystallizer considering the action of electromagnetic braking and the collision and aggregation behavior of argon bubbles-inclusions to obtain simulation results of a flow field, a temperature field, a solidified shell distribution and a motion behavior of discrete phases in the crystallizer at different times.

2. The method of simulating the behavior of particles movement and interaction in a continuous casting mold according to claim 1, wherein, In step S1, the geometric structure parameters of the continuous casting crystallizer include a width, a height and a thickness of the crystallizer, and diameters, an outlet height, an outlet width and an outlet position of a submerged nozzle.

3. The method of simulating the behavior of particles movement and interaction in a continuous casting mold according to claim 1, wherein, In step S2, during the fluid domain volume extraction and structured grid division of the three-dimensional geometric model of the continuous casting crystallizer, a local boundary layer grid encryption operation is performed on a region near a wall surface of the fluid domain to accurately calculate the growth of a solidified shell.

4. The method of simulating the behavior of particles movement and interaction in a continuous casting mold according to claim 1, wherein, Step S3 specifically comprises: S31: selecting a calculation model and a solving algorithm: selecting a large eddy simulation model to solve the turbulent motion of molten steel in the crystallizer, selecting a volume of fluid model to solve the fluctuation behavior of a molten steel-mold powder interface, enabling an energy conservation equation to solve the heat transfer behavior of molten steel in the crystallizer, selecting a solidification and melting model to solve the solidification and melting behavior of molten steel and defining a shell movement speed according to a withdrawal rate, and selecting a magnetohydrodynamic model to solve the influence of an electromagnetic field on the flow behavior of molten steel; performing pressure-velocity coupling by using a coupling algorithm, spatially discretizing pressure by using an alternating pressure algorithm, spatially discretizing momentum by using a bounded central difference format algorithm, and respectively discretizing an energy equation and a magnetohydrodynamic equation by using a second-order upwind and a first-order upwind format; and solving by using a bounded second-order implicit transient formula to ensure the stability of calculation; S32: defining physical property parameters and boundary conditions: setting the density, viscosity, thermal conductivity, specific heat capacity, latent heat, liquidus temperature, solidus temperature, electrical conductivity and magnetic permeability parameters of molten steel and mold powder, and setting the density of argon bubbles and inclusions; The submerged nozzle inlet is set as a velocity inlet boundary condition, a specific inlet velocity value is calculated in combination with a withdrawal rate and a section size, an inlet temperature value is set as a steel liquid pouring temperature, and a discrete phase boundary condition type at the inlet is set as rebound; a top surface of the crystallizer is set as an adiabatic slip wall surface boundary condition, a discrete phase boundary condition type at the top surface of the crystallizer is set as escape; a bottom surface of the crystallizer is set as a fluid outflow outlet Outflow boundary condition, a discrete phase boundary condition type at the bottom surface of the crystallizer is set as escape; and a side wall surface of the crystallizer is set as a no-slip wall surface boundary condition, a heat exchange type is convection heat exchange, and a convection heat exchange coefficient is determined according to an empirical formula of a heat flow density of a continuous casting crystallizer, and the formula is as follows: , wherein h is a crystallizer side wall heat transfer coefficient, A and B are both empirical constants calculated according to the water volume of the crystallizer, y is a coordinate in the direction of drawing, v is a drawing speed, T and T ref are the wall temperature and the reference temperature, respectively, the reference temperature is the ambient temperature of the crystallizer; the type of the discrete phase boundary condition of the crystallizer side wall is set as escape. S33: After initializing the flow field and temperature field of the calculation domain, set the solving parameters and perform iterative solving.

5. The method of simulating the behavior of particles motion and interaction in a continuous casting mold according to claim 4, wherein, In step S32, the inlet velocity value is calculated in combination with the withdrawal rate and the cross-sectional size, specifically: Inlet velocity = (withdrawal rate × cross-sectional area of crystallizer) / inlet area of nozzle.

6. The method of simulating the behavior of particles movement and interaction in a continuous casting mold according to claim 1, wherein, In step S4, the following steps are specifically included: S41: Obtain inclusion radius R p , establish the injection point of argon bubble and inclusion, select the entrance of submerged entry nozzle as the injection point, and set the size of argon bubble and inclusion; S42: Calculate the floating removal behavior of argon bubbles and inclusions at the steel slag interface and the capture behavior of argon bubbles and inclusions at the solidification front, and when the argon bubbles or inclusions move to the mold powder volume fraction or solid fraction reaching the detachment condition, the corresponding argon bubbles or inclusion particles are removed from the calculation domain, i.e. the first remaining argon bubbles and the first remaining inclusions are obtained; S43: Calculate the collision aggregation behavior of the first remaining argon bubbles and the first remaining inclusions obtained in step S42, obtain the position coordinates x b , y b , z b and the velocity components v b,x , v b,y , v b,z of each direction of the first remaining argon bubbles in the calculation domain at the current time, and the position coordinates x p , y p , z p and the velocity components v p,x , v p,y , v p,z of each direction of the first remaining inclusions, and set the calculation time step t, calculate the potential collision zone radius R c based on the velocity of each direction of the first remaining argon bubbles and the time step, as follows: , define the inclusion particles with a distance from the argon bubble less than Rc as the first potential collision inclusion; S44: According to the vector synthesis method, calculate the velocity included angle θ between all first remaining argon bubbles and first potential collision inclusions, and screen out the first potential collision inclusions with the included angle within the range of the collision angle, which are defined as the second potential collision inclusions; S45: Divide the time step t into n parts, and according to the position coordinates and velocity in each direction of the first remaining argon bubbles and the second potential collision inclusions, calculate the position coordinates of the first remaining argon bubbles and the second potential collision inclusions in the i-th state within t seconds, 1≤i≤n, and the calculation formula is as follows: ， ， ， ， ， where x b,(i / n)t , y b,(i / n)t and z b,(i / n)t are the position coordinates of the first remaining argon bubble in the i-th state at t seconds, and x p,(i / n)t , y p,(i / n)t and z p,(i / n)t are the position coordinates of the second potential collision inclusions in the i-th state at t seconds; S46: Calculate the distance D between the first remaining argon bubble and the second potential collision inclusion at the i / n moment according to the position coordinates of each argon bubble and inclusion obtained in step S45 i As shown below: , define the spherical center distance D between the inclusion and the argon bubble when the distance is less than the sum of the radii of both i If the distance is less than the sum of the radii of both, then the corresponding inclusion and bubble collide, i.e. the inclusion is to be removed. The inclusion to be removed is removed from the first remaining inclusions to obtain second remaining inclusions, and the second remaining inclusions and the first remaining argon bubbles have a motion behavior, i.e. the motion behavior of the argon bubbles and inclusions in the crystallizer is obtained.

7. The method of simulating the behavior of particles motion and interaction in a continuous casting mold according to claim 6, wherein, The radius Rp of the inclusions in step S41 is obtained by: sampling the casting blank, observing and measuring the size of the inclusions by electron microscopy; and the radius R of the argon bubbles is 1-5x10 b m. -3 m.

8. The method of simulating the behavior of particles movement and interaction in a continuous casting mold according to claim 6, wherein, The condition for disengagement in step S42 is specifically that the volume fraction f of the protective slag phase slag ≥ 0.5 or the solid fraction f solid ≥ 0.

7.

9. The method of simulating the behavior of particles movement and interaction in a continuous casting mold according to claim 6, wherein, In step S44, the range of the collision angle is -90 to 90°.

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