Method for predicting spatial distribution of positions and velocities of cold sprayed ti-al composite powder particles

Abstract

The present application relates to a kind of cold spraying Ti-Al composite powder particle position and velocity space distribution prediction method, first establish the three-dimensional geometric model of Laval nozzle and substrate for cold spraying, then simulate the data of Ti particle and Al particle position distribution and velocity space distribution on substrate surface in finite element simulation calculation software, and then the data is integrated to obtain the position distribution and velocity space distribution of composite powder particle in the process of cold spraying particle collision on substrate surface, different acceleration gas pressure and powder feeding gas pressure difference and Ti and Al particle size, output form and spraying speed are given, the position distribution graph and velocity space distribution graph under a plurality of different spraying simulation conditions are obtained, i.e. it realizes Ti-Al composite powder particle position and velocity space distribution prediction.The present application method is simple, low in cost, and has important guiding significance for the study of cold spraying Ti-Al composite coating and other composite coatings.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of surface engineering, in particular to a method for predicting the distribution position and velocity of particles colliding with the surface of a substrate in a cold spraying process. BACKGROUND

[0002] Cold spraying is an advanced powder particle solid deposition technology based on aerodynamics and high-speed collision dynamics. In cold spraying, high-pressure gas is first introduced into a converging-diverging Laval nozzle. After the gas flows through the throat of the nozzle, supersonic flow is generated. Then, the spraying powder is sent into the gas stream from the upstream of the nozzle by the powder feeding gas. The powder particles are accelerated to a speed of 300-1200 m / s through the entire nozzle, forming a high-speed particle stream and impacting the substrate, causing strong plastic deformation of the substrate and effective bonding with the substrate without melting. The particles remain solid throughout the deposition process, effectively avoiding defects caused by high temperature and temperature changes. Cold spraying is suitable for temperature-sensitive materials, oxidation-sensitive materials, and phase-change-sensitive materials, such as aluminum, copper, titanium, and their alloys. Currently, cold spraying has been successfully used to prepare most pure metals, alloys, metal matrix composites, nanostructured metal coatings or bulk materials, etc.

[0003] Because cold spraying can form effective bonding between particles and substrate, particles and particles without melting, and has low porosity and high deposition efficiency. When cold spraying Ti-Al composite powder, the density, particle size, material properties, and other factors of the two particles may cause different particle position distribution and velocity spatial distribution at the substrate, resulting in different particle deposition position, thickness, and density after spraying, which further affects the final microstructure and performance of the coating. However, due to the high-speed characteristics of cold sprayed particles, the velocity and spatial distribution of particles colliding with the substrate cannot be directly obtained from the experimental process, which inevitably makes the final microstructure and performance uncontrollable. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art by providing a method for predicting the position and velocity spatial distribution of Ti-Al composite powder particles in the cold spraying process, effectively controlling the final microstructure and performance, and overcoming the problem of difficult direct acquisition of particle velocity and spatial distribution with different characteristics in the cold spraying composite powder process.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: a method for predicting the position and velocity spatial distribution of Ti-Al composite powder particles in cold spraying, comprising the following steps:

[0006] Step 1: Establish a three-dimensional geometric model of the Laval nozzle and the substrate for cold spraying according to the given parameters of the Laval nozzle and the substrate;

[0007] wherein the parameters of the Laval nozzle include the diameter of the throat, the diameters of the accelerating gas inlet and the powder feeding gas inlet, the length of the upstream converging section, the length of the downstream diverging section, the diameter of the powder feeding tube; the parameter of the substrate is the thickness of the substrate;

[0008] Step two, in the finite element simulation software, set the symmetry axis of the Laval nozzle, the accelerating gas inlet and the powder feeding gas inlet, the outlet, the outflow boundary, the inner wall surface, the throat and the surface of the substrate as the calculation region;

[0009] At the same time, set the boundary and boundary conditions of the calculation region, and the gas properties of the accelerating gas and the powder feeding gas, and then obtain the gas flow field trajectory, velocity and temperature of the Laval nozzle through finite element simulation calculation;

[0010] Step three, set the position of the sprayed particles injected into the Laval nozzle as the powder feeding gas inlet, the injection mode of the sprayed particles as perpendicular to the surface, and the particle size distribution as Rosin-Rammler distribution, and randomly release the particles at the powder feeding gas inlet;

[0011] Then, set the sprayed particles as Ti particles and Al particles, respectively, and the average particle size, output form and spraying speed of the Ti particles and Al particles, and then use finite element simulation calculation to obtain the data of the position distribution and velocity space distribution of the Ti particles and Al particles on the substrate surface;

[0012] Integrate the data of the position distribution and velocity space distribution of the Ti particles and Al particles on the substrate surface, and obtain the position distribution and velocity space distribution of the particle collision on the substrate surface in the Ti-Al composite powder particle cold spraying process;

[0013] Step four, given different accelerating gas pressure and powder feeding gas pressure difference, and Ti and Al particle size, output form and spraying speed, obtain the position distribution graph and velocity space distribution graph under multiple different spraying simulation conditions, that is, realize the prediction of the position and velocity space distribution of Ti-Al composite powder particles.

[0014] Further, the gas flow field, velocity slice cloud picture, pressure slice cloud picture and streamline trajectory in the Laval nozzle are obtained from step two, which are used to observe the influence of different working gas pressure and powder feeding gas pressure difference and Ti and Al particle size, spraying speed on the position distribution and velocity space distribution of the sprayed particles.

[0015] Further, the inner wall surface of the Laval nozzle and the substrate surface in step two are set as no-slip boundary and adiabatic boundary conditions, and the boundary condition type of the inner wall surface of the Laval nozzle is escape, and the boundary condition type of the substrate is trap.

[0016] Further, the step two further comprises meshing the three-dimensional geometric model of the cold sprayed Laval nozzle and the substrate, and adding a boundary layer at the near-wall surface of the cold sprayed Laval nozzle and the throat region during meshing, the mesh type of the meshed calculation domain is hexahedral mesh, and the number of meshes is higher than 6 million.

[0017] Further, the step two further comprises setting the boundary and boundary condition of the calculation region, and the gas attribute of the accelerating gas and the powder feeding gas, and further obtaining the gas flow field trajectory, velocity and temperature of the Laval nozzle through finite element simulation calculation, specifically comprising the following steps:

[0018] Step 21, setting the gas inflow boundary as the corresponding region of the accelerating gas inlet and the powder feeding gas inlet of the Laval nozzle, and the outflow boundary as the external jet region corresponding to the outlet, setting the inner wall surface of the Laval nozzle and the surface of the substrate as the boundary condition, and setting the inlet pressure of the accelerating gas inlet and the powder feeding gas inlet of the Laval nozzle and the outlet pressure of the external jet region as the boundary condition;

[0019] Step 22, selecting inert gas as the accelerating gas and the powder feeding gas, taking the inert gas as ideal gas, and setting the attribute of the inert gas to include: density compressibility, specific heat capacity described by a segmented polynomial, thermal conductivity set as a constant, and simultaneously, limiting the viscosity of the inert gas changing with temperature based on Sutherland law;

[0020] Step 23, solving the gas flow field on the calculation region by using a density-based coupled implicit solver;

[0021] Step 24, in the finite element simulation calculation software, taking the basic control equations of fluid solution as the three basic conservation equations of mass, momentum and energy, and establishing a standard k-ε turbulent flow model, so as to obtain the gas flow field trajectory, velocity and temperature of the Laval nozzle.

[0022] Further, the inert gas is nitrogen, helium or argon.

[0023] Further, the finite element simulation calculation in the step three is specifically:

[0024] setting the spraying particle characteristics to solve the acceleration and heating process of the particles by using a discrete phase model and the shape of the spraying particles; according to the calculation region, the boundary and boundary condition of the calculation region, and the temperature and pressure difference of the accelerating gas and the powder feeding gas of the Laval nozzle, the data of the position distribution and velocity space distribution of Ti particles and Al particles on the surface of the substrate are obtained.

[0025] Further, in the finite element simulation calculation, the interaction between the spraying particles and the gas flow and the mutual influence between the particles are ignored, and the shape of the spraying particles is spherical.

[0026] Further, the initial value ΔP of the pressure difference generated by the accelerating gas and the powder feeding gas in step four is 0.1-0.7 Mpa.

[0027] Further, the throat diameter in the Laval nozzle parameters is 2-2.7 mm, the accelerating gas inlet diameter is 10-20 mm, the length of the upstream convergent section is 20-30 mm, the length of the downstream divergent section is 100-220 mm, and the diameter of the powder feeder is 1.5 mm; the substrate parameters are that the substrate thickness is 10-20 mm.

[0028] The method has the beneficial effects that the method for obtaining the position distribution and the velocity spatial distribution of particles on a substrate surface in a cold spraying process of Ti-Al composite powder is disclosed, specifically, a three-dimensional geometric model of a Laval nozzle is established by using SolidWorks software; the three-dimensional geometric model of the Laval nozzle is meshed by using a finite element simulation calculation software, and after the calculation region, the solving method and the calculation condition are set, the particle flow field trajectory and the information of the particles on the substrate surface are solved; then the process of the collision of the two kinds of particles with the substrate is simulated and post-processed by using MATLAB software, and finally the position distribution and the velocity spatial distribution of the particles in the cold spraying process of Ti-Al composite powder are obtained.

[0029] The simulation calculation method solves the problem that the velocity and the spatial distribution of particles with different characteristics in the cold spraying process of composite powder are difficult to directly obtain, lays a foundation for subsequent research on the deposition behavior of the two kinds of particles and the performance of the coating, and has the advantages of simple operation process, wide application range and low cost. In addition, the technical analysis method is suitable for analyzing the position distribution and the velocity spatial distribution of any two kinds of material composite powder particles on a substrate surface in a cold spraying process, and provides a new method for researching the deposition behavior of the composite powder particles and the position distribution and the velocity spatial distribution on the substrate surface in the cold spraying process. The method has important guiding significance for researching the Ti-Al composite coating and other composite coatings. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The three-dimensional model schematic diagram of the convergent-divergent Laval nozzle structure;

[0031] Figure 2 The position distribution and the velocity distribution of particles on a substrate surface in a cold spraying process of sprayed particles under the same conditions,

[0032] (a) is the position distribution and the velocity distribution schematic diagram of Al particles; (b) is the position distribution and the velocity distribution schematic diagram of Ti particles, and (c) is the position distribution and the velocity distribution schematic diagram of Ti-Al composite powder particles. DETAILED DESCRIPTION

[0033] The principles and features of the present application are described below in conjunction with the accompanying drawings, in which the examples are used to explain the present application and are not intended to limit the scope of the present application.

[0034] In order to achieve the above-mentioned purpose, the present application provides the following specific embodiments:

[0035] Embodiment 1: A cold spraying Ti-Al composite powder particle position and velocity space distribution prediction method, comprising the following steps:

[0036] Step 1: Establish a three-dimensional geometric model of the Laval nozzle and the substrate for cold spraying according to the given Laval nozzle and substrate parameters;

[0037] Wherein the Laval nozzle parameters include the diameter of the throat 7, the diameter of the accelerating gas inlet 1 and the powder feeding gas inlet 2, the length of the upstream converging section 8, the length of the downstream diverging section 9, and the diameter of the powder feeding tube; the substrate parameter is the substrate thickness;

[0038] The throat 7 diameter in the Laval nozzle parameters is 2-2.7mm, the accelerating gas inlet 1 diameter is 10-20mm, the length of the upstream converging section 8 is 20-30mm, the length of the downstream diverging section 9 is 100-220mm, and the diameter of the powder feeder 5 is 1.5mm; the substrate parameter is the substrate thickness of 10-20mm;

[0039] Step 2: In the finite element simulation calculation software, set the symmetry axis of the Laval nozzle, the accelerating gas inlet 1 and the powder feeding gas inlet 2, the outlet 3, the outflow boundary 4, the inner wall surface 5, the throat 7, and the surface 6 of the substrate as the calculation region; wherein the inner wall surface of the Laval nozzle and the surface of the substrate are both set as no-slip boundary and adiabatic boundary conditions, and the boundary condition type of the inner wall surface of the Laval nozzle is escape, and the boundary condition type of the substrate is trap;

[0040] Step 3: Grid division is performed on the three-dimensional geometric model of the cold spraying Laval nozzle and the substrate, and boundary layers are added at the near-wall surface of the cold spraying Laval nozzle and the throat region during grid division; the grid type of the grid division calculation domain is hexahedral grid, and the number of grids is higher than six million.

[0041] Step 4: Set the corresponding regions of the accelerating gas inlet 1 and the powder feeding gas inlet 2 of the Laval nozzle as the gas inflow boundary, the external jet region corresponding to the outlet 3 as the outflow boundary 4, set the inner wall surface 5 of the Laval nozzle and the surface 6 of the substrate as the boundary conditions, and set the inlet pressure of the accelerating gas inlet 1 and the powder feeding gas inlet 2 of the Laval nozzle, the outlet pressure of the outlet and the external jet region as the boundary conditions;

[0042] Step 5: Selecting inert gas as accelerating gas and powder feeding gas, the inert gas is nitrogen or helium or argon, the inert gas is regarded as ideal gas, and the properties of the inert gas are set, including: density compressibility, specific heat capacity described by piecewise polynomial, thermal conductivity set as constant, at the same time, the viscosity of the inert gas is defined based on Sutherland law to change with temperature;

[0043] Step 6: Solving the gas flow field on the calculation region by using the density-based coupled implicit solver;

[0044] Step 7: In the finite element simulation calculation software, the basic control equations of fluid solution are three basic conservation equations of mass, momentum and energy, at the same time, the standard k-ε turbulence model is established, that is, the gas flow field trajectory, velocity and temperature of the Laval nozzle, as well as the gas flow field, velocity slice cloud picture, pressure slice cloud picture and streamline trajectory in the Laval nozzle are obtained, which are used to observe the influence of different working gas pressure and powder feeding gas pressure difference, Ti and Al particle size and spraying speed on the position distribution and velocity space distribution of sprayed particles.

[0045] Step 8: Setting the position of the sprayed particle injected into the Laval nozzle as the powder feeding gas inlet, the sprayed particle injection mode as perpendicular to the surface injection, the particle size distribution as Rosin-Rammler distribution, and the particle is randomly released at the powder feeding gas inlet; and setting the sprayed particle as Ti particle and Al particle, and the average particle size, output form and spraying speed of Ti particle and Al particle;

[0046] Step 9: Setting the sprayed particle characteristics as solving the acceleration and heating process of the particle by using the discrete phase model and the shape of the sprayed particle; according to the calculation region, the boundary and boundary conditions of the calculation region, the temperature and pressure difference of the accelerating gas and powder feeding gas of the Laval nozzle, the position distribution and velocity space distribution of Ti particle and Al particle on the surface of the substrate are obtained; and the interaction between the sprayed particle and the gas flow and the mutual influence between the particles are ignored, and the shape of the sprayed particle is spherical.

[0047] Step 10: Integrating the position distribution and velocity space distribution of Ti particle and Al particle on the surface of the substrate, the position distribution and velocity space distribution of particle collision on the surface of the substrate in the Ti-Al composite powder particle cold spraying process are obtained;

[0048] Step 11: Given different accelerating gas pressure and powder feeding gas pressure difference, Ti and Al particle size, output form and spraying speed, the position distribution and velocity space distribution under multiple spraying simulation conditions are obtained, that is, the position and velocity space distribution prediction of Ti-Al composite powder particle is realized; wherein, the initial value ΔP of the pressure difference generated by the accelerating gas and the powder feeding gas is 0.1-0.7 Mpa.

[0049] In order to further illustrate the scheme of the present application and the effect of the present application, the following specific test examples are provided:

[0050] A three-dimensional geometric model of the Laval nozzle is established using SolidWorks software; the three-dimensional geometric model of the Laval nozzle is meshed using computational fluid dynamics software FLUENT, the calculation region, calculation condition and solving method are set, and then the particle flow field trajectory and the information of the particles on the substrate surface are obtained by solving calculation; the results of the collision between the two kinds of particles and the substrate are post-processed using MATLAB software.

[0051] The specific steps of the specific test example are as follows:

[0052] S1, set the actual size of the converging-diverging Laval nozzle and the substrate, including the throat diameter of 2.7 mm, the inlet diameter of 20 mm, the upstream converging section length of 30 mm, the downstream expanding section length of 220 mm, the powder feeder diameter of 1.5 mm, the substrate thickness of 10 mm, and establish a three-dimensional geometric model using SolidWorks software;

[0053] S2, mesh the nozzle geometric model in the finite element simulation calculation software, in order to make the result more accurate, the boundary of the nozzle geometric model is meshed, the boundary layer is added at the near-wall surface of the cold spraying Laval nozzle and the throat region, the mesh type of the calculation domain is hexahedral mesh, and the number of meshes is six million.

[0054] S3, set the gas inlet corresponding area of the Laval nozzle as the gas inflow boundary, the external jet area corresponding to the outlet (3) as the outflow boundary, set the inner wall surface of the Laval nozzle and the substrate surface as the boundary condition, and set the inlet pressure of the powder feeding gas and accelerating gas, the outlet pressure of the outlet and external jet area as the boundary condition; wherein, the inner wall surface of the Laval nozzle and the substrate surface are both set as no-slip boundary and adiabatic boundary condition, and the boundary condition type of the inner wall surface of the Laval nozzle is escape, and the boundary condition type of the substrate is trap;

[0055] S4, set the shape of the sprayed particles as spherical, select nitrogen as the accelerating gas and powder feeding gas, and set the nitrogen as ideal gas, and set the properties of nitrogen including: density compressible, specific heat capacity described by piecewise polynomial, thermal conductivity set as constant, at the same time, based on Sutherland law, the change process of nitrogen viscosity with temperature is limited, the mutual influence of particles on gas flow and the mutual influence between particles can be ignored.

[0056] S5, in the finite element simulation calculation software, setting the calculation region, solution method and calculation condition, and defining the solver type, using the density-based coupled implicit solver to calculate the airflow field on the calculation domain; the basic control equation of fluid solution is respectively the three basic conservation equations of mass, momentum and energy, the turbulence model is established, and the standard k-ε turbulence model is adopted;

[0057] S6, setting the temperature and pressure of the powder feeding gas as 300K and 4MPa respectively, and the temperature and pressure of the accelerating gas as 773K and 3.9MPa respectively, and the initial pressure difference ΔP generated is 0.1MPa;

[0058] S7, setting the spraying particle parameters, setting the particle size distribution of the sprayed Ti particles as Rosin-Rammler, the maximum particle size as 0.053mm, the minimum particle size as 0.015mm, and the average particle size as 0.032mm, and calculating in the finite element simulation calculation software to obtain the data of the position distribution and velocity space distribution of the Ti particles on the substrate surface;

[0059] S8, repeating step S7, setting the corresponding parameters of the sprayed Al particles, the particle size distribution of the Al particles is Rosin-Rammler, the maximum particle size is 0.06mm, the minimum particle size is 0.03mm, and the average particle size is 0.045mm, and calculating in the finite element simulation calculation software to obtain the data of the position distribution and velocity space distribution of the Al particles on the substrate surface;

[0060] S9, post-processing based on the results of the finite element simulation calculation software: analyzing the Ti and Al particle cold spraying results, observing the flow field in the Laval nozzle, the velocity slice cloud picture, the pressure slice cloud picture, the streamline trajectory and the particle position distribution on the substrate surface. For the three-dimensional geometric model of the Laval nozzle, integrating the position distribution and velocity space distribution of the Ti and Al particles on the substrate, and making the position distribution diagram and the velocity space distribution diagram in the MATLAB software;

[0061] Then, by changing the difference between the accelerating gas pressure and the powder feeding gas pressure, and the particle size and spraying speed of the Ti and Al particles, the finite element simulation calculation software is used for calculation, and the changes of the above factors on the particle position distribution and velocity space distribution on the substrate surface are analyzed.

[0062] The results of this test example are shown in the attached Figure 2 Since the nozzle model is a three-dimensional axisymmetric structure, the results output here are symmetric about the XY plane. Figure 2In the figure, the coordinate system represents the position distribution of the particles on the surface of the substrate, the color represents the size of the velocity, the circular scatter points represent Ti particles, the triangular scatter points represent Al particles, and the size of the scatter points represents the particle size of the individual particles, i.e. the position distribution and velocity space distribution on the surface of the substrate after the cold spraying of the Ti-Al composite powder particles can be directly observed.

[0063] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for predicting the spatial distribution of position and velocity of cold-sprayed Ti-Al composite powder particles, characterized in that: The following steps are involved: Step 1: Establish a three-dimensional geometric model of the Laval nozzle and substrate for cold spraying according to the given Laval nozzle and substrate parameters; The Laval nozzle parameters include the diameter of the throat (7), the diameters of the accelerating gas inlet (1) and the powder feeding gas inlet (2), the length of the upstream contraction section (8), the length of the downstream expansion section (9), and the diameter of the powder feeding pipe; the matrix parameters are the matrix thickness; Step 2: In the finite element simulation calculation software, the symmetry axis of the Laval nozzle, the accelerating gas inlet (1), the powder feeding gas inlet (2), the outlet (3), the outflow boundary (4), the inner wall surface (5), the throat (7) and the surface (6) of the substrate are set as the calculation area; At the same time, the boundary and boundary conditions of the calculation area and the gas properties of the accelerating gas and the powder feeding gas are set, and then the airflow field trajectory, velocity and temperature of the Laval nozzle are obtained through finite element simulation calculation; Step 3: Set the position where the spray particles are injected into the Laval nozzle to the powder feeding gas inlet, the spray particle injection method to be perpendicular to the surface, the particle size distribution to be Rosin-Rammler distribution, and randomly release particles at the powder feeding gas inlet; Next, the spraying particles were set to Ti particles and Al particles, as well as their average particle size, output form, and spray speed. Finite element simulation was then used to calculate the position distribution and velocity spatial distribution data of the Ti and Al particles on the substrate surface. The data of the position distribution and velocity spatial distribution of the Ti and Al particles on the substrate surface are integrated to obtain the position distribution and velocity spatial distribution of the particles colliding on the substrate surface during the cold spraying process of the Ti and Al composite powder particles; Step 4. Given different accelerating gas pressures and powder feeding gas pressure differences, as well as the particle sizes, output forms, and spraying velocities of Ti and Al particles, the position distribution maps and velocity spatial distribution maps under various spraying simulation conditions are obtained, thus realizing the prediction of the position and velocity spatial distribution of Ti-Al composite powder particles.

2. The method for predicting the spatial distribution of position and velocity of cold sprayed Ti-Al composite powder particles according to claim 1, wherein: The airflow field, velocity slice cloud map, pressure slice cloud map, and streamline trajectory in the Laval nozzle are also obtained from the second step, which are used to observe the effects of different working gas pressures and powder feeding gas pressure differences, as well as the particle size of Ti and Al particles and the spraying speed on the spraying particle position distribution and velocity spatial distribution.

3. The method for predicting the spatial distribution of position and velocity of cold sprayed Ti-Al composite powder particles according to claim 1, wherein: In step 2, the inner wall surface and the substrate surface of the Laval nozzle are both set to no-slip boundary and adiabatic boundary conditions, and the boundary condition type of the inner wall surface of the Laval nozzle is escape, and the boundary condition type of the substrate is trap.

4. The method for predicting the spatial distribution of position and velocity of cold sprayed Ti-Al composite powder particles according to claim 1, wherein: The step 2 also includes meshing the three-dimensional geometric model of the cold-sprayed Laval nozzle and the substrate. During meshing, a boundary layer is added to the near-wall surface and throat area of ​​the cold-sprayed Laval nozzle. The mesh type of the meshing calculation domain is a hexahedral mesh, and the number of meshes is greater than six million.

5. The method for predicting the spatial distribution of position and velocity of cold sprayed Ti-Al composite powder particles according to claim 1, wherein: Step 2 sets the boundaries and boundary conditions of the calculation area and the gas properties of the accelerating gas and the powder feeding gas. Then, the airflow field trajectory, velocity, and temperature of the Laval nozzle are obtained through finite element simulation. Specifically, the following steps are included: Step 21, with the areas corresponding to the accelerating gas inlet (1) and the powder feeding gas inlet (2) of the Laval nozzle as the gas inflow boundary, and the external jet area corresponding to the outlet (3) as the outflow boundary (4), the inner wall surface (5) of the Laval nozzle and the surface (6) of the substrate are set as boundary conditions, and the inlet pressure of the accelerating gas inlet (1) and the powder feeding gas inlet (2) of the Laval nozzle, the outlet pressure and the outlet pressure of the external jet area are set as boundary conditions; Step 22: Select an inert gas as the accelerating gas and powder feeding gas, treat the inert gas as an ideal gas, and set the properties of the inert gas to include: compressible density, specific heat capacity described by a piecewise polynomial, and thermal conductivity set to a constant. At the same time, the variation of the inert gas viscosity with temperature is limited based on Sutherland's law; Step 23: solving the airflow field on the calculation area using a density-based coupled implicit solver; Step 24. In the finite element simulation software, the basic control equations solved for the fluid are the three basic conservation equations of mass, momentum, and energy. At the same time, a standard k-ε turbulence model is established to obtain the airflow field trajectory, velocity, and temperature of the Laval nozzle.

6. The method for predicting the spatial distribution of position and velocity of cold sprayed Ti-Al composite powder particles according to claim 5, wherein: The inert gas is nitrogen, helium or argon.

7. The method for predicting the spatial distribution of position and velocity of cold sprayed Ti-Al composite powder particles according to claim 1, wherein: The finite element simulation calculation used in step 3 is specifically as follows: The spray particle characteristics are set to use a discrete phase model to solve the particle acceleration and heating process and the spray particle shape; based on the calculation area and the boundary and boundary conditions of the calculation area, the temperature and pressure difference of the accelerating gas and the powder feeding gas of the Laval nozzle, the position distribution and velocity spatial distribution data of the Ti particles and Al particles on the substrate surface are obtained.

8. The method for predicting the spatial distribution of position and velocity of cold sprayed Ti-Al composite powder particles according to claim 7, wherein: In the finite element simulation calculation, the interaction between the sprayed particles and the gas flow and the mutual influence between the particles are set to be negligible, and the shape of the sprayed particles is spherical.

9. The method for predicting the spatial distribution of position and velocity of cold sprayed Ti-Al composite powder particles according to claim 7, wherein: The initial value ΔP of the pressure difference between the accelerating gas and the powder feeding gas in step 4 is 0.1-0.7 MPa.

10. The method for predicting the spatial distribution of position and velocity of cold sprayed Ti-Al composite powder particles according to any one of claims 1 to 9, wherein: The parameters of the Laval nozzle include a throat diameter of 2 to 2.7 mm, an accelerating gas inlet diameter of 10 to 20 mm, an upstream contraction section length of 20 to 30 mm, a downstream expansion section length of 100 to 220 mm, and a powder feeder diameter of 1.5 mm. The substrate parameters include a substrate thickness of 10 to 20 mm.

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