A method for simulating heat transfer characteristics of welding arc under fast-frequency pulse current

Abstract

The present invention provides a method for simulating the heat transfer characteristics of a welding arc under a fast-frequency pulse current, comprising the following steps: constructing a fast-frequency pulse welding arc model; importing the meshed fast-frequency pulse welding arc model into Fluent software; defining the physical properties of the shielding gas and the material of the welding workpiece; specifying the boundary type and boundary conditions; setting control parameters and relaxation factors; initializing the welding arc calculation area and the welding workpiece calculation area; solving the welding arc calculation area; simulating the fast-frequency pulse welding arc under different welding currents, and / or simulating the fast-frequency pulse welding arc under different fast-frequency frequencies. This method can simulate the arc morphology and arc pressure curve under different welding currents and different fast-frequency frequencies, which is beneficial for studying the arc contraction effect, arc radial size, arc stiffness, etc., and selecting better parameters for arc welding.

Description

Technical Field

[0001] The present invention relates to the technical field of heat transfer characteristics of welding arcs, and more particularly to a method for simulating heat transfer characteristics of welding arcs under fast-frequency pulse current. Background Art

[0002] Conventional pulsed TIG power supplies, hampered by advances in power electronics and digital control technologies, struggle to simultaneously achieve ultra-high pulse frequencies and superimpose high and low-frequency pulse currents. This limits the TIG welding process, resulting in common issues such as slow welding speeds, poor arc energy concentration, and high heat input. This is particularly problematic for welding heat-sensitive high-temperature alloy components such as titanium and nickel-based alloys, as well as precision-machined workpieces. Consequently, the demand for more precise, flexible, and high-frequency pulsed TIG welding technology is urgent. To optimize TIG welding process characteristics and expand its application, welding current waveform control has become a key research focus. Fast-frequency pulsed TIG welding technology has significantly enhanced the performance of fast-frequency pulsed power supplies through improvements in both hardware and software. By superimposing high-frequency pulse currents ≥20 kHz on low-frequency pulse currents, it achieves flexible control of high and low-frequency pulses, significantly improving power supply performance and process applicability, making it a key technology for high-performance TIG welding applications. Due to the cyclical variations in the fast-frequency current and the increased number of welding process parameters, the flow and thermal fields are significantly more complex than those of traditional TIG welding, further posing a significant challenge in properly matching welding specification parameters. In-depth research on the welding process using numerical simulation technology has important theoretical significance and engineering application prospects for understanding the essence of weld formation, optimizing welding process parameters, and controlling the heat-affected zone. However, the existing welding arc model has not yet considered the influence of high-frequency current, so there is a problem that the fast-frequency welding arc model needs to be improved. Summary of the Invention

[0003] In order to overcome the shortcomings and deficiencies in the prior art, the purpose of the present invention is to provide a method for simulating the heat transfer characteristics of a welding arc under a fast-frequency pulse current; this method can simulate the arc shape and arc pressure curve under different welding currents and different fast-frequency conditions, which is conducive to studying the arc contraction effect, arc radial size, arc stiffness, etc., and selecting better parameters for arc welding, thereby forming a weld with a narrower weld width and deeper penetration, and achieving the purpose of reducing the heat-affected zone when the heat input is the same.

[0004] In order to achieve the above object, the present invention is implemented by the following technical solution: a method for simulating the heat transfer characteristics of a welding arc under a fast-frequency pulse current, comprising the following steps:

[0005] S1. Construct a fast-frequency pulse welding arc model; set a welding arc calculation area, a welding workpiece calculation area, a shielding gas inlet, and a shielding gas outlet in the fast-frequency pulse welding arc model; and mesh the fast-frequency pulse welding arc model using a finite element meshing method;

[0006] S2. Importing the meshed fast-frequency pulse welding arc model into Fluent software; in Fluent software, setting a pressure-based solver and setting a set of governing equations in two-dimensional coordinates; the governing equations include a mass conservation equation, an axial momentum conservation equation, a radial momentum conservation equation, and an energy conservation equation;

[0007] The mass conservation equation is:

[0008] The conservation equation of axial momentum is:

[0009] The radial momentum conservation equation is:

[0010] The energy conservation equation is:

[0011] Among them, f z and f r are the axial and radial Lorentz force components, S u is the source term of the energy conservation equation,

[0012] ρ is the density of liquid metal; z and r represent the axial direction and radial direction of the fast-frequency pulse welding arc model, respectively; u and v are the axial velocity and radial velocity of the fluid, respectively; P is the fluid pressure; c p is the specific heat capacity at constant pressure; T is the thermodynamic temperature; κ is the thermal conductivity; j z and j r are the axial and radial components of the current density, respectively; B is the magnetic induction intensity; σ is the electrical conductivity; k B is the Boltzmann constant; e is the electron charge; S R is the radiative heat loss; is the partial differential symbol; μ is the dynamic viscosity coefficient of liquid metal; the fluid consists of liquid metal fluid and welding arc plasma fluid; liquid metal fluid refers to the liquid metal fluid formed by welding workpieces;

[0013] For the fast-frequency pulse welding arc model, the welding arc calculation area is set to the laminar flow model, and the welding workpiece calculation area is set to the laminar flow model and solidification melting model;

[0014] S3. Define the physical properties of the shielding gas and the material of the welding workpiece in Fluent software;

[0015] S4. In the Fluent software, specify the boundary type and boundary conditions for each boundary of the welding arc calculation area and the welding workpiece calculation area;

[0016] S5. In Fluent software, set the control parameters and relaxation factors;

[0017] S6. Initializing the welding arc calculation area and the welding workpiece calculation area;

[0018] S7, calculating and solving the fluid pressure p, the fluid axial flow velocity u, and the fluid radial flow velocity v in the welding arc calculation area and the welding workpiece calculation area;

[0019] S8. Perform fast-frequency pulse welding arc simulation at different welding currents and / or perform fast-frequency pulse welding arc simulation at different fast-frequency frequencies.

[0020] Preferably, in said S7, the calculation method for solving the fluid pressure p, the fluid axial velocity u and the fluid radial velocity v is as follows: first, assuming the initialized fluid axial velocity u0 and the initialized fluid radial velocity v0, substitute them into the momentum discrete equation for calculation, the momentum discrete equation refers to the equation obtained by discretizing the control equation group; secondly, assuming the fluid pressure p, solve the momentum discrete equation to obtain the trial fluid axial velocity u* and the trial fluid radial velocity v*; solve the pressure correction equation to obtain the fluid pressure correction value p*; according to the fluid The pressure correction value p*, the trial-calculated fluid axial flow velocity u* and the trial-calculated fluid radial flow velocity v* are used to solve the improved fluid pressure, fluid axial flow velocity and fluid radial flow velocity; the improved fluid axial flow velocity and fluid radial flow velocity are used to solve the momentum discrete equation, and the improved fluid pressure is used as the fluid pressure correction value p* of the next level; it is determined whether the solution converges: if the solution does not converge, the fast-frequency pulse welding arc model and boundary conditions are checked, and the fast-frequency pulse welding arc model and boundary conditions are modified and recalculated until convergence.

[0021] Preferably, the pressure correction equation is a pressure correction equation obtained by substituting the relationship between the fluid pressure and the fluid axial velocity, and the relationship between the fluid pressure and the fluid radial velocity, obtained from the discrete forms of the axial momentum conservation equation and the radial momentum conservation equation, into the discrete form of the fluid continuity equation;

[0022] The fluid continuity equation is:

[0023] Where t is the solution time.

[0024] Preferably, in said S4, the boundary conditions include velocity, temperature and current density.

[0025] Preferably, in said S5, the relaxation factors set include pressure, density, body force, momentum, velocity, and energy.

[0026] Preferably, in said S6, the welding arc calculation area is initialized, including initializing the initial temperature of the welding arc calculation area; the initial temperature of the welding arc calculation area is 10000K.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] The simulation method of the present invention can simulate the arc shape and arc pressure curve under different welding currents and different fast frequency conditions by constructing a fast-frequency pulse welding arc model, which is conducive to studying the arc contraction effect, arc radial size, arc stiffness, etc., and selecting better parameters for arc welding, thereby forming a weld with a narrower weld width and deeper penetration, and achieving the purpose of reducing the heat-affected zone when the heat input is the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 1. It is a flow chart of a method for simulating heat transfer characteristics of a welding arc under a fast-frequency pulse current according to the present invention;

[0030] Figure 2 It is a flow chart of the computational domain solution of the present invention;

[0031] Figure 3 It is a schematic diagram of the fast-frequency pulse welding arc model of the present invention;

[0032] Figure 4 This is a comparison diagram of arc shapes obtained by simulation at different welding currents of the present invention;

[0033] Figure 5 This is a curve diagram of arc pressure obtained by simulation at different welding currents of the present invention;

[0034] Figure 6 This is a comparison diagram of arc shapes obtained by simulation at different fast frequency of the present invention;

[0035] Figure 7 This is a curve diagram of arc pressure obtained by simulation at different fast frequency of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0037] Example 1

[0038] This embodiment provides a method for simulating the heat transfer characteristics of a welding arc under a fast-frequency pulse current, comprising the following steps:

[0039] S1. Construct a fast-frequency pulse welding arc model; set the welding arc calculation area, welding workpiece calculation area, shielding gas inlet, and shielding gas outlet in the fast-frequency pulse welding arc model; and mesh the fast-frequency pulse welding arc model using a finite element meshing method.

[0040] S2. Importing the meshed fast-frequency pulse welding arc model into Fluent software; in Fluent software, setting a pressure-based solver and setting a set of governing equations in two-dimensional coordinates; the governing equations include a mass conservation equation, an axial momentum conservation equation, a radial momentum conservation equation, and an energy conservation equation;

[0041] The mass conservation equation is:

[0042] The conservation equation of axial momentum is:

[0043] The radial momentum conservation equation is:

[0044] The energy conservation equation is:

[0045] Among them, f z and f r are the axial and radial Lorentz force components, S u is the source term of the energy conservation equation,

[0046] ρ is the density of liquid metal; z and r represent the axial direction and radial direction of the fast-frequency pulse welding arc model, respectively; u and v are the axial velocity and radial velocity of the fluid, respectively; P is the fluid pressure; c p is the specific heat capacity at constant pressure; T is the thermodynamic temperature; κ is the thermal conductivity; j z and j r are the axial and radial components of the current density, respectively; B is the magnetic induction intensity; σ is the electrical conductivity; k B is the Boltzmann constant; e is the electron charge; S R is the radiative heat loss; is the partial differential symbol; μ is the dynamic viscosity coefficient of liquid metal; the fluid consists of liquid metal fluid and welding arc plasma fluid; liquid metal fluid refers to the liquid metal fluid formed by welding workpieces;

[0047] For the fast-frequency pulse welding arc model, the welding arc calculation area is set as the laminar flow model, and the welding workpiece calculation area is set as the laminar flow model and the solidification melting model.

[0048] S3. In Fluent software, define the physical properties of the shielding gas and the material of the welding workpiece.

[0049] S4. In the Fluent software, specify the boundary type and boundary conditions for each boundary of the welding arc calculation area and the welding workpiece calculation area; the boundary conditions include velocity, temperature and current density.

[0050] S5. In Fluent software, set the control parameters and relaxation factors. The relaxation factors to be set include pressure, density, volume force, momentum, velocity, and energy.

[0051] S6. Initializing the welding arc calculation area and the welding workpiece calculation area. Initializing the welding arc calculation area includes initializing the initial temperature of the welding arc calculation area; the initial temperature of the welding arc calculation area is 10000K.

[0052] S7. Calculate and solve the fluid pressure p, the fluid axial velocity u, and the fluid radial velocity v in the welding arc calculation area and the welding workpiece calculation area.

[0053] Specifically, if Figure 2 As shown, the calculation method for fluid pressure p, fluid axial velocity u and fluid radial velocity v is:

[0054] First, assume the initialization of the fluid axial velocity u0 and the initialization of the fluid radial velocity v0, and substitute them into the momentum discrete equation for calculation. The momentum discrete equation refers to the equation obtained by discretizing the control equation group.

[0055] Next, assuming the fluid pressure p, solve the momentum discrete equation to obtain the estimated axial velocity u* and radial velocity v* of the fluid; solve the pressure correction equation to obtain the fluid pressure correction value p*. The pressure correction equation is obtained by substituting the relationships between fluid pressure and axial velocity, and between fluid pressure and radial velocity, obtained from the discrete forms of the axial momentum conservation equation and the radial momentum conservation equation, into the discrete form of the fluid continuity equation to obtain the pressure correction equation.

[0056] The fluid continuity equation is:

[0057] Where t is the solution time;

[0058] Solve the improved fluid pressure, fluid axial velocity, and fluid radial velocity based on the fluid pressure correction value p*, the calculated fluid axial velocity u*, and the calculated fluid radial velocity v*; solve the momentum discrete equation using the improved fluid axial velocity and fluid radial velocity, and use the improved fluid pressure as the fluid pressure correction value p* at the next level;

[0059] Determine whether the solution converges: If the solution does not converge, check the fast-frequency pulse welding arc model and boundary conditions, modify the fast-frequency pulse welding arc model and boundary conditions, and recalculate until convergence.

[0060] S8. Perform fast-frequency pulse welding arc simulation at different welding currents and / or perform fast-frequency pulse welding arc simulation at different fast-frequency frequencies.

[0061] Example 2

[0062] This embodiment provides a method for simulating the heat transfer characteristics of a welding arc under a fast-frequency pulse current, comprising the following steps:

[0063] S1. Construct a fast-frequency pulse welding arc model; set the welding arc calculation area, welding workpiece calculation area, shielding gas inlet, and shielding gas outlet in the fast-frequency pulse welding arc model; and mesh the fast-frequency pulse welding arc model using a finite element meshing method.

[0064] like Figure 3 As shown, ABCD represents the nozzle part, CDBEFG is the welding arc calculation domain, BE is the shielding gas inlet, EF represents the shielding gas outlet, and GF represents the welding workpiece calculation domain. The finite element meshing method is used with Gambit software. According to the characteristics of the welding arc calculation area and the welding workpiece calculation area, the fast-frequency pulse welding arc model is divided into regions to generate a hexahedral structured grid. The boundary is first divided proportionally and then swept. The grid is encrypted near the tungsten electrode and the base material. The ratio of the grid unit size to the encrypted grid unit size in other areas is not less than 2, and each area has a uniform transition. The grid is imported into Fluent software and checked for negative volume problems. Argon is used as the shielding gas with a flow rate of 10L / min. The tungsten electrode tip cone angle is 60°, the arc length is 10 mm, the tungsten electrode diameter is 2 mm, the welding voltage is 12 V, and the welding speed is 5 mm / s. Based on the simulation analysis of the DC welding arc model, the high-temperature ionized gas generated by the arc is substituted into the fast-frequency pulse welding arc model as the inlet condition for iterative calculation. The flow inlet is located on the xoy plane, and the welding arc movement direction is the positive direction of the x-axis. The welding workpiece is made of 304 stainless steel with a plate thickness of 6 mm, a plate length of 14 mm, and a plate width of 8 mm.

[0065] S2. Importing the meshed fast-frequency pulse welding arc model into Fluent software; in Fluent software, setting a pressure-based solver and setting a set of governing equations in two-dimensional coordinates; the governing equations include a mass conservation equation, an axial momentum conservation equation, a radial momentum conservation equation, and an energy conservation equation;

[0066] The mass conservation equation is:

[0067] The conservation equation of axial momentum is:

[0068] The radial momentum conservation equation is:

[0069] The energy conservation equation is:

[0070] Among them, f z and f r are the axial and radial Lorentz force components, S u is the source term of the energy conservation equation,

[0071] ρ is the density of liquid metal; z and r represent the axial direction and radial direction of the fast-frequency pulse welding arc model, respectively; u and v are the axial velocity and radial velocity of the fluid, respectively; P is the fluid pressure; c p is the specific heat capacity at constant pressure; T is the thermodynamic temperature; κ is the thermal conductivity; j z and j r are the axial and radial components of the current density, respectively; B is the magnetic induction intensity; σ is the electrical conductivity; k B is the Boltzmann constant; e is the electron charge; S R is the radiative heat loss; is the partial differential symbol; μ is the dynamic viscosity coefficient of liquid metal;

[0072] For the fast-frequency pulse welding arc model, the welding arc calculation area is set as the laminar flow model, and the welding workpiece calculation area is set as the laminar flow model and the solidification melting model.

[0073] S3. In Fluent software, define the physical properties of the shielding gas and the material of the welding workpiece.

[0074] Based on the thermophysical parameters of argon, including the relationship between density, resistivity, thermal conductivity, and viscosity and temperature, and the physical parameters of stainless steel, the properties of the two materials are added. The available methods for determining the thermophysical parameters of the welded workpiece include similarity, interpolation, and extrapolation. Parameter addition can be accomplished by programming in the user-defined section of the Fluent software.

[0075] S4. In the Fluent software, specify the boundary type and boundary conditions for each boundary of the welding arc calculation area and the welding workpiece calculation area; the boundary conditions include velocity, temperature and current density.

[0076] Set the inlet and outlet of argon in the welding arc calculation area, give the argon flow rate, calculate the inlet velocity according to the inlet size, set the workpiece surface, and select a rational temperature constant according to the actual welding and ambient temperature; similarly, set the tungsten electrode wall, and select the temperature constant as the temperature boundary condition; in order to solve the problem of implementing fast-frequency pulse current in the fast-frequency pulse welding arc model, the current continuity equation boundary condition is set in the form of a given current density, and the arc density is defined by setting the current size through a formula, and the current pulse is realized through a periodic function; the present invention adopts the form of a sine function. When the function value is greater than zero, the peak current is set. When the function value is less than 0, the base current is set. The loading of the fast-frequency current is realized through a user-defined panel.

[0077] S5. In Fluent software, set the control parameters and relaxation factors. The relaxation factors to be set include pressure, density, volume force, momentum, velocity, and energy.

[0078] S6. Initializing the welding arc calculation area and the welding workpiece calculation area. Initializing the welding arc calculation area includes initializing the initial temperature of the welding arc calculation area; the initial temperature of the welding arc calculation area is 10000K.

[0079] S7. Calculate and solve the fluid pressure p, the fluid axial velocity u, and the fluid radial velocity v in the welding arc calculation area and the welding workpiece calculation area.

[0080] Specifically, the calculation method for fluid pressure p, fluid axial velocity u, and fluid radial velocity v is:

[0081] First, assume the initialization of the fluid axial velocity u0 and the initialization of the fluid radial velocity v0, and substitute them into the momentum discrete equation for calculation. The momentum discrete equation refers to the equation obtained by discretizing the control equation group.

[0082] Next, assuming the fluid pressure p, solve the momentum discrete equation to obtain the estimated axial velocity u* and radial velocity v* of the fluid; solve the pressure correction equation to obtain the fluid pressure correction value p*. The pressure correction equation is obtained by substituting the relationships between fluid pressure and axial velocity, and between fluid pressure and radial velocity, obtained from the discrete forms of the axial momentum conservation equation and the radial momentum conservation equation, into the discrete form of the fluid continuity equation to obtain the pressure correction equation.

[0083] The fluid continuity equation is:

[0084] Where t is the solution time;

[0085] Solve the improved fluid pressure, fluid axial velocity, and fluid radial velocity based on the fluid pressure correction value p*, the calculated fluid axial velocity u*, and the calculated fluid radial velocity v*; solve the momentum discrete equation using the improved fluid axial velocity and fluid radial velocity, and use the improved fluid pressure as the fluid pressure correction value p* at the next level;

[0086] Determine whether the solution converges: If the solution does not converge, check the fast-frequency pulse welding arc model and boundary conditions, modify the fast-frequency pulse welding arc model and boundary conditions, and recalculate until convergence.

[0087] S8. Perform fast-frequency pulse welding arc simulation at different welding currents and / or perform fast-frequency pulse welding arc simulation at different fast-frequency frequencies.

[0088] Specifically, if Figure 4 and Figure 5 Figure 2 shows a simulation of a fast-frequency pulsed TIG welding arc under different welding currents. While maintaining the same fast-frequency, the arc shrinks as the current increases, while the arc pressure increases with increasing current. Compared to the case without fast-frequency current, applying a current of 50A shrinks the arc diameter from 5.10mm to 4.12mm, and the arc pressure increases from 55Pa to 86Pa. Without fast-frequency current, the maximum arc temperature is 12678K. With the addition of fast-frequency current, the maximum arc temperature reaches 13005K. When the pulse current reaches above 10kHz, the arc is compressed due to the electromagnetic contraction effect and the shielding airflow generated by the arc shape. The arc pressure can be more than 4 times the steady-state DC arc pressure. This not only increases the weld penetration, but also has a strong electromagnetic stirring effect on the molten pool metal, which is beneficial to refine the grains, reduce weld defects and obtain good weld joints.

[0089] like Figure 6 and Figure 7 As shown in the figure, the simulation of the fast-frequency pulse TIG welding arc at different fast-frequency frequencies shows that when the welding current is the same, the welding frequency parameter is gradually increased from 10kHz to 30kHz. When the welding frequency parameter is 10kHz, 15kHz, 20kHz, 25kHz, and 30kHz respectively, the arc shows a trend of contraction as the fast-frequency frequency increases, while the arc pressure first increases and then decreases with the increase of the fast-frequency frequency. This shows that the increase of the fast-frequency pulse current amplitude and fast-frequency pulse frequency makes the arc contract more significantly, resulting in a narrower weld width and deeper weld penetration.

[0090] Through research and experiments on the above-mentioned embodiments, the research method of the present invention can significantly affect arc characteristics and weld performance by varying the amplitude and frequency of the fast-frequency pulse current while maintaining the same welding voltage and welding speed. Increasing the fast-frequency current or frequency can significantly reduce the arc's radial dimension, enhance arc stiffness, and stabilize the arc, resulting in a narrower weld width and deeper penetration. While maintaining the same heat input, this method also reduces the heat-affected zone.

[0091] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for simulating the heat transfer characteristics of a welding arc under a fast-frequency pulse current, characterized by: The following steps are involved: S1. Construct a fast-frequency pulse welding arc model; set a welding arc calculation area, a welding workpiece calculation area, a shielding gas inlet, and a shielding gas outlet in the fast-frequency pulse welding arc model; and mesh the fast-frequency pulse welding arc model using a finite element meshing method; S2. Importing the meshed fast-frequency pulse welding arc model into Fluent software; in Fluent software, setting a pressure-based solver and setting a set of governing equations in two-dimensional coordinates; the governing equations include a mass conservation equation, an axial momentum conservation equation, a radial momentum conservation equation, and an energy conservation equation; The mass conservation equation is: The conservation equation of axial momentum is: The radial momentum conservation equation is: The energy conservation equation is: Among them, f z and f r are the axial and radial Lorentz force components, S u is the source term of the energy conservation equation, ρ is the density of liquid metal; z and r represent the axial direction and radial direction of the fast-frequency pulse welding arc model respectively; u and v are the axial flow velocity and radial flow velocity of the fluid respectively; p is the fluid pressure; c p is the specific heat capacity at constant pressure; T is the thermodynamic temperature; κ is the thermal conductivity; j z and j r The current density is The axial and radial components; B is the magnetic induction intensity; σ is the electrical conductivity; k B is the Boltzmann constant; e is the electron charge; S R is the radiative heat loss; is the partial differential symbol; μ is the dynamic viscosity coefficient of liquid metal; the fluid consists of liquid metal fluid and welding arc plasma fluid; liquid metal fluid refers to the liquid metal fluid formed by welding workpieces; For the fast-frequency pulse welding arc model, the welding arc calculation area is set to the laminar flow model, and the welding workpiece calculation area is set to the laminar flow model and solidification melting model; S3. Define the physical properties of the shielding gas and the material of the welding workpiece in Fluent software; S4. In the Fluent software, specify the boundary type and boundary conditions for each boundary of the welding arc calculation area and the welding workpiece calculation area; S5. In Fluent software, set the control parameters and relaxation factors; S6. Initializing the welding arc calculation area and the welding workpiece calculation area; S7, calculating and solving the fluid pressure p, the fluid axial flow velocity u, and the fluid radial flow velocity v in the welding arc calculation area and the welding workpiece calculation area; S8. Perform fast-frequency pulse welding arc simulation at different welding currents and / or perform fast-frequency pulse welding arc simulation at different fast-frequency frequencies.

2. The method for simulating heat transfer characteristics of a welding arc under a fast-frequency pulse current according to claim 1, characterized in that: In S7, the calculation method for solving the fluid pressure p, the fluid axial flow velocity u and the fluid radial flow velocity v is: first, assume the initialized fluid axial flow velocity u0 and the initialized fluid radial flow velocity v0, and substitute them into the momentum discrete equation for calculation. The momentum discrete equation refers to the equation obtained after discretizing the control equation group; secondly, assume the fluid pressure p, solve the momentum discrete equation, and obtain the trial fluid axial flow velocity u* and the trial fluid radial flow velocity v*; solve the pressure correction equation to obtain the fluid pressure correction value p*; solve the improved fluid pressure, fluid axial flow velocity and fluid radial flow velocity according to the fluid pressure correction value p*, the trial fluid axial flow velocity u* and the trial fluid radial flow velocity v*; use the improved fluid axial flow velocity and fluid radial flow velocity to solve the momentum discrete equation, and use the improved fluid pressure as the fluid pressure correction value p* of the next level; judge whether the solution converges: if it does not converge after the solution, check the fast-frequency pulse welding arc model and boundary conditions, modify the fast-frequency pulse welding arc model and boundary conditions, and recalculate until convergence.

3. The method for simulating heat transfer characteristics of a welding arc under a fast-frequency pulse current according to claim 2, characterized in that: The pressure correction equation is obtained by substituting the relationship between fluid pressure and fluid axial velocity, and between fluid pressure and fluid radial velocity, obtained by discrete forms of the axial momentum conservation equation and the radial momentum conservation equation, into the discrete form of the fluid continuity equation. The fluid continuity equation is: Where t is the solution time.

4. The method for simulating heat transfer characteristics of a welding arc under a fast-frequency pulse current according to claim 1, wherein: In S4, the boundary conditions include velocity, temperature and current density.

5. The method for simulating heat transfer characteristics of a welding arc under a fast-frequency pulse current according to claim 1, wherein: In S5, the relaxation factors set include pressure, density, body force, momentum, velocity, and energy.

6. The method for simulating heat transfer characteristics of a welding arc under a fast-frequency pulse current according to claim 1, characterized in that: In the above S6, the welding arc calculation region is initialized, including initializing the initial temperature of the welding arc calculation region; the initial temperature of the welding arc calculation region is 10000K.

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