A numerical simulation method for gas-liquid two-phase flow of atomizer structure based on VOF model

Abstract

This invention relates to a numerical simulation method for gas-liquid two-phase flow in an atomizer structure based on the VOF model. The invention pertains to the field of numerical simulation technology for gas atomizers. It establishes a two-dimensional model of the gas-liquid fluid domain within the atomizing device, uses a mesh generation method to divide the computational domain of the two-phase flow numerical simulation of the atomization field, and refines the mesh in the outlet region of the liquid guide pipe. A computational fluid dynamics solver is used to solve the numerical simulation of the two-phase flow of a single-stage metal liquid breakup. Boundary conditions for the atomizer's working pressure are set according to the gas atomization powdering process, and the physical conditions of the computational domain are initialized. A computational fluid dynamics post-processing method is used to output the numerical simulation results of the motion characteristics of each fluid phase in the computational domain. This invention can obtain more accurate transient gas-liquid flow characteristics while overcoming the enormous computational demands of direct numerical simulation, which requires solving all turbulence information.

Description

Technical Field

[0001] This invention relates to the field of numerical simulation technology for gas atomizers, and is a numerical simulation method for gas-liquid two-phase flow of atomizer structure based on the VOF model. Background Technology

[0002] Gas atomization powder preparation technology has significant practical value in high-end manufacturing fields such as aerospace and 3D printing due to its superior properties, including excellent purity, uniform particle morphology, controllable performance, and low equipment cost. It has become one of the core technologies for metal powder preparation. This process uses high-pressure, high-speed inert gases (such as argon (Ar) or nitrogen (N2)) to impact the molten metal, breaking it into tiny droplets. These droplets are then rapidly cooled through convection and heat conduction with the gas flow, solidifying into powder. The entire gas atomization powder preparation process involves a deep integration of multiple disciplines, including fluid mechanics, heat conduction, and solidification kinetics.

[0003] The granulation effect of gas atomization is influenced by numerous parameters, including the pressure, temperature, and type of atomizing gas, the structure of the atomizing nozzle, the wettability of the molten metal, and superheat. Among these, the atomizer structure primarily affects the size and distribution of atomized particles. Simultaneously, the atomizer structure also determines the morphology and velocity of the flow field formed by the atomized gas. Different flow field distributions and gas velocities result in different fragmentation mechanisms and atomization efficiencies for the molten metal, collectively influencing the powder particle size distribution and morphology.

[0004] Based on the above analysis, the existing technology has the following problems: In the powder preparation process, the atomization of molten metal is due to its strong interaction with high-speed gas flow. Therefore, obtaining a gas flow field environment with excellent atomization effect is a key factor in optimizing the powder preparation process. In addition, there are many influencing factors in the gas atomization process, and the liquid atomization and powder forming processes are complex and rapid, and difficult to observe directly.

[0005] The significance of solving the above problems is as follows: This invention fully considers the influence of the gas flow field morphology on the powder particle size distribution during atomization, and studies the morphology of the gas-liquid two-phase flow field under different extension lengths and front-end structures of the gas guide tube. This has guiding significance for improving production efficiency without modifying other process parameters. The simulation results have guiding significance for optimizing the structure of tightly coupled atomizers and adjusting subsequent atomization processes. Summary of the Invention

[0006] This invention addresses the problems of existing technologies by disclosing a numerical simulation method for gas-liquid two-phase flow of an atomizer structure based on the VOF model. This invention calculates the airflow field distribution and the fragmentation morphology of a single layer of liquid metal using the finite element method. Within the framework of a tightly coupled atomizer structure, it clarifies the influence of the extension length of the air guide tube and the front-end structure on the particle fragmentation effect and the final particle size.

[0007] This invention provides the following technical solutions: A numerical simulation method for gas-liquid two-phase flow of an atomizer structure based on a VOF model, the method comprising the following steps: Step 1: Establish a two-dimensional model of the gas-liquid fluid domain within the atomizing device. Based on the extension length of the liquid guide tube in the tightly coupled atomizer structure and the front-end structure, establish a two-phase flow numerical simulation calculation domain for the atomized gas-liquid flow field. Step 2: The computational domain for the two-phase flow numerical simulation of the atomization field is divided into grids using the grid generation method, and the grid is refined in the region of the liquid guide tube outlet. Step 3: Use a computational fluid dynamics solver to solve the numerical simulation of the two-phase flow of molten metal breaking in one step. Set the boundary conditions of the working pressure of the atomizer according to the gas atomization powder making process, and initialize the physical conditions of each physical condition in the computational domain. Step 4: Use computational fluid dynamics post-processing to output the numerical simulation results of the motion characteristics of each fluid phase in the computational domain.

[0008] Preferably, a two-dimensional model of the atomizer structure and gas-liquid fluid domain in the atomization process is established using SolidWorks; the extension dimensions of the liquid guide tube are set to 0mm, 2mm, and 4mm.

[0009] Preferably, Ansys meshing is used to mesh the computational domain of the atomized two-phase flow numerical simulation, and the mesh is refined for the regions of the gas pipe outlet and the molten metal outlet.

[0010] Preferably, Ansys Fluent is used to solve the numerical simulation of the gas-liquid two-phase flow field in the atomization process. A pressure-based transient solver is used, gravity and direction are defined, and the standard k-omega turbulence model is selected for numerical simulation calculation. The gas phase material in the fluid domain is argon (ideal gas), the working pressure of the atomizer is set to 10 MPa, and the inlet flow velocity is 0.5 m / s.

[0011] Preferably, the boundary conditions are set to a fixed wall with no slippage, and the inlet is set to a velocity inlet; the initialization conditions are set according to the actual working conditions.

[0012] Preferably, the physical conditions of the computational domain are initialized, the pressure-velocity coupling uses the PISO algorithm, and the convergence residual is set to 1e. -5The initial calculation time step is set to 1e. -7 The total calculation time is 10ms, and the numerical simulation of the gas-liquid two-phase flow begins.

[0013] Preferably, the computational fluid dynamics solution establishes a two-phase flow mathematical model of gas-liquid coupled flow based on the Navier-Stokes fundamental equations and the turbulence equations, including: The continuity equation, momentum equation, and energy equation are obtained as follows: Continuity equation:

[0014] Momentum equation:

[0015] Energy equation:

[0016] When molten metal interacts with high-speed gas flow, a suitable turbulence model is used to solve the dynamic behavior of the gas-liquid two phases: Turbulence model:

[0017] .

[0018] Preferably, the numerical simulation results of the two-phase flow of argon gas and high-temperature alloy melt are calculated and output using CFD-POST, and the morphology cloud map, gas flow field velocity cloud map and velocity vector map, as well as the turbulent kinetic energy distribution map of the gas flow field are extracted when the molten metal is initially broken.

[0019] A computer-readable storage medium having a computer program stored thereon, which is executed by a processor to implement a numerical simulation method for gas-liquid two-phase flow of an atomizer structure based on a VOF model.

[0020] A computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement a numerical simulation method for gas-liquid two-phase flow based on atomizer structure under a VOF model.

[0021] The present invention has the following beneficial effects: In existing technologies, experimental methods are typically used to study single-phase gas flow in gas atomization powder production processes. However, in practice, adjusting the atomizer structure is complex and costly. This invention employs a standard k-omega (SST) turbulence model to capture the gas flow field morphology, while using a second-order upwind model to maintain accuracy. Furthermore, the use of a two-dimensional model improves computational efficiency compared to a three-dimensional model while ensuring accuracy. This method can obtain more accurate transient gas-liquid flow characteristics, including the location and structure of gas vortices, the instantaneous velocity distribution of the gas flow field, and the fragmentation morphology of the liquid phase. Simultaneously, it overcomes the enormous computational demands of direct numerical simulation, which requires solving for all turbulence information.

[0022] The numerical simulation method for gas-liquid two-phase flow based on the VOF model provided by this invention can accurately simulate the gas-liquid two-phase motion in the atomization process, clarifying the influence of the extension length of the liquid guide tube and the outlet structure of the atomizer on the gas flow field morphology and the fragmentation morphology of the molten metal. The simulation process closely approximates the actual situation. Compared with experimental in-situ measurement methods, it has the advantages of low cost and high research efficiency. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a flowchart of the method of the present invention; Figure 2 These are transient liquid phase fragmentation cloud maps under different structural conditions; Figure 3 These are transient gas flow field velocity contour maps under different structural conditions; Figure 4 These are vector diagrams of transient high-speed gas flow fields under different structural conditions; Figure 5 This is a diagram showing the turbulent kinetic energy distribution of the airflow field under different structural conditions. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0026] The present invention will be described in detail below with reference to specific embodiments. Specific Implementation Example 1: according to Figures 1 to 5 As shown, the specific optimization technical solution adopted by the present invention to solve the above-mentioned technical problems is: The present invention relates to a numerical simulation method for gas-liquid two-phase flow of atomizer structure based on VOF model.

[0028] This invention provides a numerical simulation method for gas-liquid two-phase flow of an atomizer structure based on a VOF model. The method includes the following steps: Step 1: Establish a two-dimensional model of the gas-liquid fluid domain within the atomizing device. Based on the extension length of the liquid guide tube in the tightly coupled atomizer structure and the front-end structure, establish a two-phase flow numerical simulation calculation domain for the atomized gas-liquid flow field. A two-dimensional model of the atomizer structure and gas-liquid fluid domain in the atomization process was established using SolidWorks; the extension dimensions of the liquid guide tube were set to 0 mm, 2 mm, and 4 mm.

[0029] Step 2: The computational domain for the two-phase flow numerical simulation of the atomization field is divided into grids using the grid generation method, and the grid is refined in the region of the liquid guide tube outlet. Ansys meshing was used to mesh the computational domain of the atomized two-phase flow numerical simulation, and the mesh was refined for the regions of the gas outlet and the molten metal outlet.

[0030] Step 3: Use a computational fluid dynamics solver to solve the numerical simulation of the two-phase flow of molten metal breaking in one step. Set the boundary conditions of the working pressure of the atomizer according to the gas atomization powder making process, and initialize the physical conditions of each physical condition in the computational domain. Ansys Fluent was used to solve the gas-liquid two-phase flow field in the atomization process. A pressure-based transient solver was used, gravity and direction were defined, and the standard k-omega turbulence model was selected for numerical simulation. The gas phase material in the fluid domain was argon (ideal gas), the atomizer working pressure was set to 10 MPa, and the inlet flow velocity was 0.5 m / s.

[0031] The boundary conditions are set to a fixed wall with no slippage, and the inlet is set to a velocity inlet; the initialization conditions are set according to the actual working conditions.

[0032] The physical conditions of the computational domain are initialized. The pressure-velocity coupling adopts the PISO algorithm, and the convergence residual is set to 1e. -5 The initial calculation time step is set to 1e. -7 The total calculation time is 10ms, and the numerical simulation of the gas-liquid two-phase flow begins.

[0033] Computational fluid dynamics solves a two-phase flow mathematical model based on the Navier-Stokes fundamental equations and turbulence equations, establishing a gas-liquid coupled flow, including: The continuity equation, momentum equation, and energy equation are obtained as follows: Continuity equation:

[0034] Momentum equation:

[0035] Energy equation:

[0036] When molten metal interacts with high-speed gas flow, a suitable turbulence model is used to solve the dynamic behavior of the gas-liquid two phases: Turbulence model:

[0037] .

[0038] Step 4: Use computational fluid dynamics post-processing to output numerical simulation results of fluid motion characteristics under gas-liquid coupling.

[0039] The two-phase flow numerical simulation results of argon gas and high-temperature alloy melt were calculated using CFD-POST. The morphology cloud map, gas flow field velocity cloud map and velocity vector map, as well as the turbulent kinetic energy distribution map of the gas flow field were extracted during the initial breakup of the molten metal.

[0040] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which is executed by a processor to implement a numerical simulation method for gas-liquid two-phase flow of an atomizer structure based on a VOF model.

[0041] The present invention also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement a numerical simulation method for gas-liquid two-phase flow based on the VOF model of an atomizer structure. Specific Implementation Example 2: The only difference between Embodiment 2 and Embodiment 1 of this application is that: A numerical simulation method for gas-liquid two-phase flow of an atomizer structure based on the VOF model includes the following steps: S1. A two-dimensional model of the gas-liquid fluid domain inside the atomizing device is established using computer-aided design software; based on the extension length of the liquid guide tube in the tightly coupled atomizer structure and the front end structure, a two-phase flow numerical simulation calculation domain for the atomized gas-liquid flow field is established. S2. Mesh generation software is used to divide the computational domain of the two-phase flow numerical simulation of the atomization field into meshes, and the mesh is refined in the area of ​​the liquid guide tube outlet. S3. A computational fluid dynamics solver is used to solve the numerical simulation of the two-phase flow of molten metal breaking in one step. A pressure-based transient solver is used, gravity and direction are defined, and the standard k-omega (SST) turbulence model is used for numerical simulation calculation. Gas parameters are defined, and boundary conditions of the atomizer working pressure are set according to the gas atomization powder making process. The physical conditions of each physical condition in the computational domain are initialized. The pressure-velocity coupling adopts the PISO algorithm. The convergence residual, calculation time step and total calculation time are set, and the numerical simulation of the two-phase flow of the atomization field is started. S4. Output the numerical simulation results of fluid motion characteristics under gas-liquid coupling using computational fluid dynamics post-processing software.

[0043] To optimize the above technical solution, the specific measures also include: In step S1, the extension length of the liquid guide tube and the structure design of the outlet end are set.

[0044] In step S3, the gas inlet is set to argon (Ar).

[0045] In step S3, the boundary conditions are set to a fixed wall with no slippage, and the inlet is set to a velocity inlet; the initialization conditions are set according to the actual working conditions.

[0046] In step S3, the computational fluid dynamics solver establishes a two-phase flow mathematical model based on the NS fundamental equations and turbulence equations to perform gas-liquid coupled flow, including: Based on the aforementioned NS fundamental equations, the continuity equation, momentum equation, and energy equation are obtained as follows: Continuity equation:

[0047] Momentum equation:

[0048] Energy equation:

[0049] When molten metal interacts with high-speed gas flow, the computational workload is large and complex, requiring the use of appropriate turbulence models to solve the dynamic behavior of the gas-liquid two phases. Turbulence model:

[0050]

[0051] In S1, a two-dimensional model of the atomizer structure and gas-liquid fluid domain in the atomization process is established using SolidWorks software; the extension dimensions of the liquid guide tube are set to 0mm, 2mm, and 4mm, and the structure of the liquid outlet is adjusted. In S2, Ansys meshing software is used to mesh the computational domain of the atomized two-phase flow numerical simulation, and the mesh is refined in the regions of the gas pipe outlet and the molten metal outlet. In S3, Ansys Fluent software was used to numerically simulate the gas-liquid two-phase flow field in the atomization process. A pressure-based transient solver was employed, gravity and its direction were defined, and the standard k-omega (SST) turbulence model was selected for numerical simulation. The gas phase material in the fluid domain was argon, an incompressible ideal gas. The atomizer operating pressure was set to 10 MPa, and the inlet velocity was 0.5 m / s. The physical conditions of the computational domain were initialized, and the pressure-velocity coupling was performed using the PISO algorithm, with the convergence residual set to 1e. -5 The initial calculation time step is set to 1e. -7 s. The total calculation time is 10ms, and the numerical simulation of the gas-liquid two-phase flow begins; In S4, the numerical simulation results of two-phase flow of argon gas and high-temperature alloy melt are calculated using CFD-POST output. The morphology cloud map, gas flow field velocity cloud map and velocity vector map, as well as the turbulent kinetic energy distribution map of the gas flow field are extracted when the molten metal is initially broken.

[0052] The above description is merely a preferred embodiment of a numerical simulation method for gas-liquid two-phase flow of an atomizer structure based on a VOF model. The scope of protection for this method is not limited to the above embodiments; all technical solutions falling within this conceptual framework are within the scope of protection of this invention. It should be noted that for those skilled in the art, any improvements and variations made without departing from the principles of this invention should also be considered within the scope of protection of this invention.

Claims

1. A numerical simulation method of gas-liquid two-phase flow based on the structure of an atomizer under the VOF model, characterized in that: The method includes the following steps: Step 1: Establish a two-dimensional model of the gas-liquid fluid domain within the atomizing device. Based on the extension length of the liquid guide tube in the tightly coupled atomizer structure and the front-end structure, establish a two-phase flow numerical simulation calculation domain for the atomized gas-liquid flow field. Step 2: The computational domain for the two-phase flow numerical simulation of the atomization field is divided into grids using the grid generation method, and the grid is refined in the region of the liquid guide tube outlet. Step 3: Use a computational fluid dynamics solver to solve the numerical simulation of the two-phase flow of molten metal breaking in one step. Set the boundary conditions of the working pressure of the atomizer according to the gas atomization powder making process, and initialize the physical conditions of each physical condition in the computational domain. Step 4: Use computational fluid dynamics post-processing to output the numerical simulation results of the motion characteristics of each fluid phase in the computational domain.

2. The method according to claim 1, characterized in that: A two-dimensional model of the atomizer structure and gas-liquid fluid domain in the atomization process was established using SolidWorks; the extension dimensions of the liquid guide tube were set to 0 mm, 2 mm, and 4 mm.

3. The method according to claim 2, characterized in that: Ansys meshing was used to mesh the computational domain of the atomized two-phase flow numerical simulation, and the mesh was refined for the regions of the gas outlet and the molten metal outlet.

4. The method according to claim 3, characterized in that: Ansys Fluent was used to solve the numerical simulation of the gas-liquid two-phase flow field in the atomization process. A pressure-based transient solver was used, gravity and direction were defined, and the standard k-omega turbulence model was selected for numerical simulation calculation. The gas phase material in the fluid domain was argon and an ideal gas. The working pressure of the atomizer was set to 10 MPa and the inlet flow velocity was 0.5 m / s.

5. The method according to claim 4, characterized in that: The boundary conditions are set to a fixed wall with no slippage, and the inlet is set to a velocity inlet; the initialization conditions are set according to the actual working conditions.

6. The method according to claim 5, characterized in that: The physical conditions of the calculation area are initialized, the pressure-velocity coupling adopts PISO algorithm, and the convergence residual is set to 1e -5 s, the calculation time step is initially set to 1e -7 s, the total calculation time is 10ms, and the numerical simulation of gas-liquid two-phase flow is started.

7. The method according to claim 6, characterized in that: Computational fluid dynamics solves a two-phase flow mathematical model based on the Navier-Stokes fundamental equations and turbulence equations, establishing a gas-liquid coupled flow, including: The continuity equation, momentum equation, and energy equation are obtained as follows: Continuity equation: Momentum equation: Energy equation: When molten metal interacts with high-speed gas flow, a suitable turbulence model is used to solve the dynamic behavior of the gas-liquid two phases: Turbulence model: 。 8. The method according to claim 7, characterized in that: The two-phase flow numerical simulation results of argon gas and high-temperature alloy melt were calculated using CFD-POST. The morphology cloud map, gas flow field velocity cloud map and velocity vector map, as well as the turbulent kinetic energy distribution map of the gas flow field were extracted during the initial breakup of the molten metal.

9. A computer readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to implement the method as claimed in any one of claims 1-8.

10. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, it implements the method of any one of claims 1-8.

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