Method for optimizing continuous casting nozzle arrangement based on cooling effect

Abstract

The invention provides a method for optimizing continuous casting nozzle arrangement based on a cooling effect, which comprises the following steps of: S1, acquiring geometric structure parameters and position parameters of nozzles in an actual production process, and establishing a nozzle three-dimensional model and a spraying area geometric model; s2, combining an internal fluid domain of the nozzle three-dimensional model with the geometric model of the spraying area, and then performing structured grid division on a computational domain; s3, calculating the grid model of the spray area computational domain by using simulation software; s4, the steam film thickness of the casting blank is determined according to the actual production working conditions, and the relation between the vertical stroke of the atomized liquid drops and the number proportion of the atomized liquid drops penetrating through the steam film is obtained through calculation in combination with the motion parameters; and S5, determining the optimal nozzle height according to the target cooling effect in combination with the relationship between the obtained vertical stroke of the atomized liquid drops and the number proportion of the atomized liquid drops penetrating through the steam film. According to the method, the simulation accuracy of continuous casting spray cooling can be effectively improved, and the optimal nozzle height can be accurately judged.

Description

Technical Field

[0001] The present invention belongs to the technical field of steel metallurgy process simulation, and particularly relates to a method for optimizing the nozzle arrangement of continuous casting based on the cooling effect. Background Art

[0002] The secondary cooling of continuous casting is an important process in the production of high-quality steel continuous casting. The reasonable control of the production process in the secondary cooling zone is the key to optimizing the solidification cooling process and improving the quality of the casting billet. During the production process, the cooling water in the secondary cooling zone is broken into a large number of atomized droplets after being ejected from the nozzle, and is sprayed onto the surface of the continuous casting billet to transfer heat with the high-temperature casting billet, ultimately achieving the effect of cooling the casting billet. However, during the production of continuous casting billets, the surface temperature of the casting billet at about 1000 °C will cause a stable steam film to form on the surface of the casting billet by the cooling water, preventing the contact heat transfer between the atomized droplets and the casting billet, and seriously affecting the secondary cooling effect. Therefore, the penetration effect of the atomized droplets on the steam film is an important index to be considered when evaluating the cooling effect of continuous casting nozzles, and is also an important reference for optimizing the nozzle arrangement in the secondary cooling of continuous casting in industrial practice.

[0003] By comparing the thickness of the steam film on the surface of the casting billet and the penetration depth of the atomized droplets, it can be judged whether the atomized droplets can conduct contact heat transfer with the casting billet. At present, researchers mainly conduct research through physical experiments and numerical simulation methods. On the one hand, researchers used PIV experiments to study the spraying characteristics of the nozzle, statistically analyzed the velocity and particle size of the ejected atomized droplets, and used the statistical results for the calculation of the droplet penetration effect; on the other hand, researchers proposed a method of using numerical simulation technology to calculate the nozzle spraying process and calculate the ability of the atomized droplets to penetrate the steam film. In the article "Influence of Nozzle Jet Characteristics on Steam Film Penetration Behavior in the Secondary Cooling Zone of Continuous Casting" (Ma Fan, Liu Qing, Zhang Jiangshan, et al. Iron & Steel, 2022, 57(10): 101-109.), a method for studying the spray cooling behavior of continuous casting secondary cooling nozzles based on numerical simulation and physical experiments was proposed. The velocity distribution of nozzle spraying was calculated by numerical simulation, and the ability to penetrate the steam film was calculated in combination with the particle size of the atomized droplets measured by physical experiments.

[0004] However, the above methods still have many deficiencies. First, relying solely on physical experiments cannot accurately and comprehensively count the velocities of a large number of atomized droplets, and existing shooting and analysis methods are difficult to handle micron-sized atomized droplets, resulting in insufficient accuracy of this method. Second, most of the existing methods combining numerical simulation with physical experiments use the VOF model to solve the nozzle jet and atomization processes. The velocities and particle sizes of the atomized droplets used to calculate the ability to penetrate the steam film are determined by simulation and experimental means respectively. Since VOF can only calculate continuous interfaces and cannot capture the motion of individual atomized droplets, the continuous phase velocity calculated by it cannot represent the actual droplet velocity, resulting in insufficient rationality of this method. Finally, the VOF model used in the existing methods combining numerical simulation with physical experiments requires a sufficiently small grid size to accurately capture the atomized droplets after fragmentation. The huge number of grids is not only difficult to divide but also time-consuming to calculate. Coupled with the need to repeat physical experiments for each working condition, this method is difficult to operate, time-consuming, and costly, and is difficult to be widely applied. Summary of the Invention

[0005] In view of the above deficiencies in the prior art, the present invention provides a method for simulating and optimizing the layout of continuous casting nozzles based on cooling effect evaluation, aiming to solve the technical problems such as low accuracy caused by the inability to count a large amount of atomized droplet information in the existing methods, insufficient rationality caused by replacing the discrete atomized droplet velocity with the continuous phase velocity, and high requirements for grid size and experimental repeatability resulting in difficult operation, long time consumption, and high cost.

[0006] Based on one aspect of the present invention, a method for optimizing the layout of continuous casting nozzles based on cooling effect is provided, including the following steps:

[0007] S1. Obtain the geometric structure parameters and position parameters of the nozzle during the actual production process, and establish a three-dimensional model of the nozzle and a geometric model of the spray zone;

[0008] S2. Extract the internal fluid domain of the three-dimensional nozzle model obtained in step S1, and merge the internal fluid domain with the geometric model of the spray zone obtained in step S1 to obtain a computational domain. Then, perform structured grid division on the computational domain to obtain a grid model of the spray zone computational domain;

[0009] S3. Use simulation software to calculate the grid model of the spray zone computational domain obtained in step S2 to obtain the motion parameters of the atomized droplets sprayed by the nozzle;

[0010] S4. Determine the thickness of the billet steam film according to the actual production working condition, and calculate the relationship between the vertical travel of the atomized droplets (i.e., the vertical distance between the atomized droplets and the nozzle outlet) and the proportion of the number of atomized droplets penetrating the steam film (i.e., the atomized droplet penetration ratio) in combination with the motion parameters obtained in S3;

[0011] S5. Determine the optimal nozzle height according to the target cooling effect and the relationship between the vertical travel of the atomized droplets obtained in step S4 and the ratio of the number of atomized droplets penetrating the steam film.

[0012] As a preferred embodiment of the method for optimizing the continuous casting nozzle layout based on the cooling effect according to the present invention, in step S1, the geometric structure parameters of the nozzle include the diameter of the nozzle, the shape of the nozzle outlet, and the diameter of the nozzle outlet; the position parameter includes the nozzle height.

[0013] As a preferred embodiment of the method for optimizing the continuous casting nozzle layout based on the cooling effect according to the present invention, in step S2, the mesh quality of the mesh model is 0.7 - 1, the number of meshes is 1 million - 1.5 million, and the junction of the nozzle outlet and the spraying area is encrypted. The encryption specifically includes increasing the number of mesh nodes within a range of 10 - 15 mm from the interface to meet the encrypted mesh size of 0.1 - 0.25 mm.

[0014] As a preferred embodiment of the method for optimizing the continuous casting nozzle layout based on the cooling effect according to the present invention, step S3 specifically includes the following steps:

[0015] S31. Select the turbulent flow in the calculation domain of the turbulence model for solution, select the VOF model and the DPM model to track the motion behavior of the spray water jet and the atomized droplets formed after the spray water is atomized respectively, and select the VOF to DPM model to solve the atomization and breakup process of the spray water;

[0016] S32. Use the coupling algorithm for pressure - velocity coupling solution, use the staggered pressure algorithm for spatial discretization of pressure, use the second - order upwind scheme for spatial discretization of momentum, and use the first - order implicit algorithm for transient solution;

[0017] S33. Set the density, viscosity, and surface tension of water and air in the continuous phase, and set the density of the atomized droplets in the discrete phase;

[0018] S34. Obtain the pressure at the nozzle inlet during the actual production process, use it as the pressure boundary condition at the nozzle inlet in the three - dimensional model of the nozzle, set the type of the discrete - phase boundary condition at the nozzle inlet in the three - dimensional model of the nozzle to rebound, set the nozzle wall as the non - slip wall boundary condition, set the type of the discrete - phase boundary condition of the nozzle wall to rebound, and set the top surface, bottom surface, and side walls of the spraying area as the pressure outlet boundary conditions, the pressure value as the atmospheric pressure, and the discrete - phase boundary condition as escape;

[0019] S35. After initializing the calculation domain, perform the solution.

[0020] As a preferred embodiment of the method for optimizing the continuous casting nozzle arrangement based on the cooling effect according to the present invention, in the step S3, the movement parameters of the atomized droplets include the vertical travel, particle size, velocity on the vertical vapor film surface, and mass.

[0021] As a preferred embodiment of the method for optimizing the continuous casting nozzle arrangement based on the cooling effect according to the present invention, the step S31 specifically includes:

[0022] S311: Enable the k-ε turbulence model and select the standard wall function for turbulence near-wall treatment;

[0023] S312: Enable the VOF model, set the number of continuous phases to 2, define the main phase as air and the secondary phase as water, enable the DPM model, and set the atomized droplet injection point to single-point injection;

[0024] S313: Enable the VOF to DPM model, set the transformed phase to water, the target phase to air, the transformation method to VOF to DPM, and set the transformation frequency, equivalent volume sphere diameter, and DPM particle packet division factor;

[0025] S314: Mark the water-vapor interface based on the liquid volume fraction, enable the grid adaptation model, define the grid refinement criteria and grid coarsening criteria, and set the encryption level, minimum encrypted volume, and encryption frequency.

[0026] As a preferred embodiment of the method for optimizing the continuous casting nozzle arrangement based on the cooling effect according to the present invention, the method further includes performing a grid model accuracy verification and optimization step after the step S3, specifically including:

[0027] 1) Conduct a spraying test using the same parameters as in the step S1, and measure the particle size of the atomized droplets ejected from the nozzle using a laser particle size analyzer;

[0028] 2) Statistically analyze the particle size of the atomized droplets obtained in the step 1) to obtain the proportion of atomized droplets in different particle size distribution ranges;

[0029] 3) Statistically analyze the proportion of atomized droplets in different particle size distribution ranges with the same vertical travel as in the step 2) obtained in the step S3;

[0030] 4) Judge the offset between the particle size distribution range and the proportion of atomized droplets obtained in the step 2) and the proportion of atomized droplets in the same particle size distribution range obtained in the step 3). If the offset between the two is within the target range, directly perform the subsequent steps; if the offset between the two exceeds the target range, optimize the grid model of S2.

[0031] As a preferred embodiment of the method for optimizing the continuous casting nozzle arrangement based on the cooling effect according to the present invention, the target range is specifically that the absolute value of the offset is not higher than 5%.

[0032] As a preferred embodiment of the method for optimizing the continuous casting nozzle arrangement based on the cooling effect according to the present invention, the optimization of the mesh model of S2 is specifically to adjust the mesh size.

[0033] As a preferred embodiment of the method for optimizing the continuous casting nozzle arrangement based on the cooling effect according to the present invention, in step S4, the number of atomized droplets penetrating the steam film is obtained by the following method:

[0034] i) Calculate the depth of the atomized droplet penetrating into the steam film, and the calculation formula is:

[0035] , where H is the thickness of the droplet penetrating the steam film, in mm; The value of is 958 kg / m 3 ; The value of is 101325 Pa; is the velocity of the droplet perpendicular to the surface of the steam film, in m / s; d is the droplet diameter, in mm;

[0036] ii) Count the number of droplets penetrating the steam film. The atomized droplets penetrating the steam film are those with the depth H of penetrating into the steam film greater than the thickness of the steam film of the atomized droplets.

[0037] As a preferred embodiment of the method for optimizing the continuous casting nozzle arrangement based on the cooling effect according to the present invention, in step S4, the calculation formula for the thickness of the steam film is:

[0038] , where C is a coefficient; is the dynamic viscosity of the steam film; is the steam thermal conductivity; is the superheat of the high-temperature wall surface; is the latent heat of vaporization; is the steam density; is the liquid density; is the liquid surface tension; g is the acceleration of gravity.

[0039] In the solution of the present invention, the target cooling effect needs to be determined in combination with the actual working conditions. Generally, the more uniform the cooling effect requirement is, the better. On this basis, according to the technical solution of the present invention, it is found that the cooling effect is strong and uniform when the proportion of the number of atomized droplets penetrating the steam film is the highest. Therefore, the nozzle height corresponding to this condition is determined as the optimal nozzle height. In addition, according to the solution of the present invention, it is also found that the cooling effect is the strongest within the range of 2% near the highest value of the proportion of the number of atomized droplets penetrating the steam film. On this basis, in combination with the error requirements for the actual installation of the nozzle, it can be determined that the nozzle heights corresponding to the range not less than 98% of the highest value of the proportion of the number of atomized droplets penetrating the steam film are all the optimal nozzle heights.

[0040] In addition, in the present invention, unless otherwise specified, the term "nozzle height" refers to the vertical distance between the nozzle water outlet and the continuous casting billet.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The technical solution of the present invention can effectively improve the simulation accuracy of continuous casting spray cooling by modeling the nozzle and the spray area, setting boundary conditions and calculation criteria.

[0043] 2. The present invention can accurately judge the most suitable nozzle height by using the proportion of atomized droplets penetrating the steam film as the standard for evaluating the spray cooling effect.

[0044] 3. The present invention simulates the spray process of the nozzle by selecting a suitable model and combining the mesh adaptive encryption technology, and further verifies the accuracy of the model by using a verification experiment, which further ensures the accuracy of the model calculation results.

[0045] 4. The present invention accurately tracks the gas-liquid interface through the VOF model and tracks the droplets formed by the atomization of the spray water through the DPM model to obtain all the atomized droplet information in the calculation domain. The accuracy is significantly improved compared with using only physical experiments. By using the numerical simulation method to directly obtain the motion parameters such as the velocity and size of each atomized droplet, it avoids the irrationality of using the continuous phase velocity to replace the discrete atomized droplet velocity to calculate the penetration effect in the prior art.

[0046] 5. By combining the mesh adaptive encryption technology, the present invention automatically encrypts the mesh at the gas-liquid interface and automatically coarsens the mesh after the discrete atomized droplets are formed, getting rid of the dependence on the mesh in the prior art. At the same time, it is no longer necessary to conduct physical experiments for multiple working conditions in sequence, significantly reducing the consumption of computing resources and experimental costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Geometric model diagram of the nozzle housing established for the embodiment of the present invention.

[0048] Figure 2 Schematic diagram of the structured grid divided for the embodiment of the present invention.

[0049] Figure 3 Partial schematic diagram of the structured grid divided for the embodiment of the present invention.

[0050] Figure 4 Relationship diagram between the spray height and the penetration ratio obtained for the embodiment of the present invention.

[0051] Figure 5 Temperature change diagram of the continuous casting billet at different spray heights obtained from the verification experiment of the embodiment of the present invention.

[0052] Wherein, D1 - nozzle diameter, H1 - nozzle length, H2 - nozzle height, D2 - diameter of the calculation area, D3 - nozzle outlet diameter. Specific implementation mode

[0053] This embodiment provides a method for optimizing the nozzle arrangement in continuous casting based on the cooling effect, including the following steps:

[0054] S1. According to the nozzles in the secondary cooling zone of a steel plant, use the ANSYS Spaceclaim 3D modeling software to establish the geometric model of the nozzle housing. As Figure 1 shown, where the nozzle length H1 is 26.8 mm, the nozzle diameter D1 is 15 mm, the nozzle outlet shape is circular, the diameter D3 is 2.8 mm, and the nozzle is arranged at a position 150 mm away from the continuous casting billet (i.e., the nozzle height H2 is 150 mm). Based on the above parameters, establish the nozzle geometric model and the spray zone geometric model. Among them, the spray zone is set as a cylinder, and the diameter D2 of the calculation area is 200 mm, as Figure 2 shown.

[0055] S2. Use the Spaceclaim 3D modeling software to extract the volume of the nozzle geometric model housing obtained in step S1 to obtain the internal fluid domain of the nozzle. After merging the internal fluid domain with the spray zone geometric model to obtain the complete calculation domain, import it into the ICEM mesh generation software. First, define and name each boundary of the model, establish Block and associate the Vertex of Block with the Point of the geometric model, and associate the Edge of Block with the Curve of the geometric model. Then, set the mesh nodes for the overall model, increase the number of mesh nodes within 15 mm from the interface, ensure that the encrypted mesh size is about 0.1 mm, the overall mesh quality is greater than 0.7, the maximum aspect ratio of a single mesh is less than 8, and the total number of meshes is about 1.2 million. The divided mesh model is as Figure 2-3 shown.

[0056] S3. Import the grid model obtained in step S2 into ANSYS Fluent simulation software. In ANSYS Fluent, select the k-ε turbulence model to solve the turbulent flow in the computational domain, and select the standard wall function for turbulent near-wall treatment; select the VOF model and DPM model to track the motion behaviors of the spray water jet and the atomized droplets formed after the atomization of the spray water respectively. Set the number of continuous phases to 2, define the primary phase as air and the secondary phase as water. Enable the DPM model and set the atomized droplet injection point to single-point injection; select the VOF to DPM model to solve the atomization and breakup process of the spray water. Enable the VOF to DPM model, set the transformed phase to water, the target phase to air, the transformation method to VOF to DPM, set the transformation frequency to 50, set the equivalent volume sphere diameter range to 0 - 0.5 mm, and set the factor for splitting the DPM particle package to 10; select the grid adaptive refinement model to refine the grid at the water-air interface. Mark the water-air interface based on the liquid volume fraction. Enable the grid adaptive model, define the grid refinement criterion as the liquid volume fraction being less than 1×10 -14 and define the grid coarsening criterion as the liquid volume fraction being greater than 1×10 -12 , set the refinement level to 4, set the minimum refinement volume to 1×10-13 m 3 , and set the refinement frequency to 20 time steps;

[0057] Use the Coupled algorithm for pressure-velocity coupling solution, use the staggered pressure algorithm (PRESTO! algorithm) for spatial discretization of pressure, use the second-order upwind scheme (Second Order Upwind) for spatial discretization of momentum, and use the first-order implicit algorithm (First Order Implicit) for transient solution to ensure the stability of the calculation;

[0058] In ANSYS Fluent software, set the density, viscosity, and surface tension of water and air in the continuous phase, and set the density of the discrete-phase atomized droplets. Among them, air is the primary phase with a density of 1.225 kg / m 3 , a viscosity of 1.7894×10 -6 Pa·s, water is the secondary phase with a density of 998.2 kg / m 3 , a viscosity of 0.001003 Pa·s, and the surface tension between air and water is 0.07275 N / m; the density of the discrete-phase atomized droplets is 998.2 kg / m 3 ;

[0059] Set the boundary conditions in the ANSYS Fluent software. Set the nozzle inlet as the pressure inlet boundary condition. According to the actual production nozzle water pressure obtained, set the specific pressure value at the nozzle inlet to 0.3 MPa, and set the discrete phase boundary condition type to bounce-back; set the nozzle wall as the no-slip wall boundary condition, and set the discrete phase boundary condition type to bounce-back; set the top surface, bottom surface and side walls of the spray area as the pressure outlet boundary condition, set the pressure value to the atmospheric pressure, and set the discrete phase boundary condition to escape;

[0060] After initializing the computational domain, start the solution to obtain the velocity of each atomized droplet perpendicular to the surface of the steam film at each vertical travel of the atomized droplets in the spray area and the droplet diameter d. Then use the formula to calculate the penetration depth of each atomized droplet through the steam film, where takes the value of 958 kg / m 3 ; takes the value of 101325 Pa.

[0061] S4. According to the actual working conditions, use the formula to calculate the thickness of the billet steam film. In the formula, C takes the value of 1.9; takes the value of 12.27 N / (m 2 ·s); takes the value of 24.78 W / (m·k); takes the value of 800℃; takes the value of 2260 kJ / kg; takes the value of 0.589 kg / m 3 ; takes the value of 958 kg / m 3 ; takes the value of 0.061 N / m; g takes the value of 9.8m / s 2 , and finally obtain the steam film thickness of 0.16 mm under the working conditions of this embodiment.

[0062] Count the ratio of the number of atomized droplets that can penetrate the steam film (i.e., H > ) to the number of atomized droplets at that height at each vertical travel calculated in S3, which is the penetration ratio of the atomized droplets at that vertical travel. As shown in Figure 4 .

[0063] S5. According to Figure 4, the vertical travel of the atomized droplets with the highest penetration ratio is 100 mm. Considering that the thickness value of the steam film on the surface of the continuous casting billet can be ignored compared with the nozzle height, and combining the height change caused by the installation operation error during actual application and the corresponding fluctuation range of the penetration ratio, based on the relationship between the vertical travel of the atomized droplets and the penetration ratio obtained in step S4, the optimal nozzle height range of this embodiment is determined to be 95 - 108 mm according to the penetration ratio not less than 98% of the maximum penetration ratio.

[0064] Verification experiment

[0065] The steel billet was heated to 900 °C using hot spraying experimental equipment in the laboratory and then spray-cooled, and the center temperature of the steel billet was recorded. During the experiment, by adjusting the nozzle height, the spray-cooling effects of the nozzle at spray heights of 90 mm, 100 mm, and 120 mm were compared respectively, and the results of the center temperature curve of the steel billet are as Figure 5 shown. Among them, the solid line is the temperature change curve of the steel billet at a spray height of 120 mm, the dashed line is the temperature change curve of the steel billet at 100 mm, and the dotted line is the temperature change curve of the steel billet at 90 mm.

[0066] It can be seen from Figure 5 that after the spraying starts, the temperature of the steel billet gradually decreases, and the decreasing speed is first fast and then slow, and finally drops to room temperature. When the spray height is 120 mm, about 40 s after the spraying starts, the temperature decreasing speed of the steel billet slows down, which is due to the formation of a steam film on the surface of the continuous casting billet, and the penetration ratio of the droplets is relatively low at a height of 120 mm, resulting in the hindrance of heat transfer. Similarly, when the spray height is 90 mm, there is also a phenomenon of the slowdown of the cooling speed of the steel billet, but the cooling effect is better than that under the condition of 120 mm. In contrast, the temperature of the steel billet drops faster and more stably at a height of 100 mm, and there is no obvious decrease in the cooling speed, which proves that a higher penetration ratio under the condition of 100 mm can bring a better spray-cooling effect, and also shows that the determination result of this method is reasonable and can be used to determine the optimal nozzle height.

Claims

1. A method for optimizing the arrangement of continuous casting nozzles based on cooling effect, characterized in that: The steps include: S1, obtain the geometric structure parameters and position parameters of the nozzle in the actual production process, and establish the nozzle three-dimensional model and the spray area geometric model; S2, extracting the internal fluid domain of the nozzle three-dimensional model obtained in step S1, and merging the internal fluid domain with the spray area geometric model obtained in step S1 to obtain a calculation domain, and then performing structured grid division on the calculation domain to obtain a grid model of the spray area calculation domain; S3, using simulation software to calculate the grid model of the spray area calculation domain obtained in step S2 to obtain the nozzle spray atomization droplet motion parameters; S4, determining the thickness of the steam film of the ingot according to the actual production working conditions, and calculating the relationship between the vertical stroke of the atomized droplets and the ratio of the number of atomized droplets penetrating the steam film in combination with the motion parameters obtained in S3; S5, determining the optimal nozzle height according to the target cooling effect and in combination with the relationship between the vertical stroke of the atomized droplets obtained in step S4 and the ratio of the number of atomized droplets penetrating the steam film, wherein the nozzle height is the vertical distance from the nozzle outlet to the surface of the ingot.

2. The method according to claim 1, characterized in that In step S1, the geometrical structural parameters of the nozzle include the nozzle diameter, the nozzle outlet shape and the nozzle outlet diameter; the position parameters include the nozzle height, which is the vertical distance from the nozzle outlet to the surface of the casting.

3. The method according to claim 1, characterized in that In step S2, the mesh quality of the mesh model is 0.7-1, the number of meshes is 1 million-1.5 million, and the mesh is encrypted at the junction of the nozzle outlet and the spray area. The encryption specifically includes increasing the number of mesh nodes within a range of 10-15 mm from the interface to ensure that the encrypted mesh size is 0.1-0.25 mm.

4. The method according to any one of claims 1 to 3, characterized in that: Step S3 specifically includes the following steps: S31, select the turbulence model to solve the turbulent flow in the calculation domain, select the VOF model and the DPM model to track the motion behaviors of the spray water jet and the atomized droplets formed after the spray water is atomized, respectively, and select the VOF to DPM model to solve the atomization and breakup process of the spray water; S32, using coupling algorithm for pressure-velocity coupling solution, using staggered pressure algorithm for spatial discretization of pressure, using second-order upwind scheme for spatial discretization of momentum, and using first-order implicit algorithm for transient solution; S33, setting the density, viscosity and surface tension of water and air in the continuous phase, and setting the density of atomized droplets in the discrete phase; S34, obtaining the pressure at the nozzle inlet during the actual production process, using it as the pressure boundary condition of the nozzle inlet in the nozzle three-dimensional model, setting the discrete phase boundary condition type of the nozzle inlet in the nozzle three-dimensional model to rebound, setting the nozzle wall to a no-slip wall boundary condition, setting the discrete phase boundary condition type of the nozzle wall to rebound, setting the top, bottom and side wall surfaces of the spraying area to pressure outlet boundary conditions, the pressure value to atmospheric pressure, and the discrete phase boundary condition to escape; S35, initializing the computational domain and then solving the problem.

5. The method according to any one of claims 1 to 3, characterized in that: In step S3, the motion parameters of the atomized droplets include vertical travel, particle size, velocity vertical to the steam film surface, and mass.

6. The method according to claim 4, characterized in that The step S31 specifically includes: S311, enable the k-ε turbulence model and select the standard wall function for turbulent near-wall processing; S312: Enable the VOF model, set the number of continuous phases to 2, define the main phase as air and the secondary phase as water, enable the DPM model, and set the atomized droplet injection point to single-point injection; S313: Enable the VOF to DPM model, set the conversion phase to water, the target phase to air, the conversion method to VOF to DPM, and set the conversion frequency, equivalent volume sphere diameter, and DPM particle packet segmentation factor; S314: Mark the water-gas interface based on the liquid volume fraction, enable the grid adaptive model, define the grid refinement standard and grid coarsening standard, set the encryption level, minimum encryption volume and encryption frequency.

7. The method according to any one of claims 1 to 3, characterized in that: The method further comprises performing a grid model accuracy verification and optimization step after step S3, specifically comprising: 1) Performing a spray test using the same parameters as in step S1, and measuring the particle size of atomized droplets sprayed from the nozzle using a laser particle size analyzer; 2) Counting the particle sizes of the atomized liquid droplets obtained in step 1) to obtain the proportions of atomized liquid droplets in different particle size distribution ranges; 3) Counting the proportions of atomized droplets with the same vertical stroke as in step 2) in different particle size distribution ranges obtained in step S3; 4) Determine the offset between the particle size distribution range and the atomized droplet ratio obtained in step 2) and the atomized droplet ratio under the same particle size distribution range obtained in step 3). If the offsets of the two are within the target range, directly execute the subsequent steps; if the offsets of the two are beyond the target range, optimize the grid model of S2.

8. The method according to claim 7, characterized in that The target range is specifically that the absolute value of the offset is no higher than 5%.

9. The method according to claim 8, characterized in that In step S4, the number of atomized droplets penetrating the steam membrane is obtained by: i) Calculate the depth of atomized droplets penetrating into the steam film, the calculation formula is: , where H is the thickness of the droplet penetrating the steam film, mm; The value is 958 kg / m 3 ; The value of is 101325 Pa; is the velocity of the droplet perpendicular to the surface of the steam film, m / s; d is the droplet diameter, mm; ii) Counting the number of droplets penetrating the steam film, i.e., the atomized droplets penetrating the steam film to a depth H greater than the thickness of the steam film of atomized droplets.

10. The method according to claim 8 or 9, characterized in that In step S4, the thickness of the steam film is calculated as follows: In the formula, C is the coefficient; is the dynamic viscosity of the steam film; is the thermal conductivity of steam; is the high temperature wall superheat; is the latent heat of vaporization; is the steam density; is the liquid density; is the surface tension of the liquid; g is the acceleration due to gravity.

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