A CFD-based method for ship painting simulation and modeling

Abstract

This invention discloses a CFD-based simulation and modeling method for ship coating. The method includes the following steps: establishing an internal flow field simulation model; establishing an external flow field simulation model; and simulation calculation. Based on CFD technology and the concept of iterative optimization, this invention provides a complete set of simulation and modeling methods encompassing both internal and external flow fields in the coating process. This method involves the simulation of two flow fields: establishing internal cavity models for different types of nozzles used in ship hull coating simulation, and creating an external flow field model for ship hull coating simulation. This model can meet the simulation needs of spray guns with different structures and models under various combinations of control parameters (spraying pressure, spraying speed, etc.). The results obtained from the internal flow field simulation are used for the external flow field simulation, ensuring the continuity of the numerical simulation. Furthermore, the simulation results of the external flow field can be fed back to the design of the nozzle's internal cavity structure for verification through simulation, demonstrating significant practical value.

Description

Technical Field

[0001] This invention relates to the field of ship hull coating technology and spraying equipment optimization, and in particular to a CFD-based method for ship coating simulation and modeling. Background Technology

[0002] With the advancement of intelligent transformation in the shipbuilding industry and the development of spraying technology, high-pressure airless spraying has been widely used in the field of ship hull coating due to its advantages such as high spraying efficiency, less paint splatter and mist, good coating uniformity, and high degree of automation. It is especially suitable for large-area rapid spraying of ship hull plating. Currently, relevant research on high-pressure airless spraying at home and abroad mainly focuses on experimental and numerical simulation studies. Domestic scholars have mainly conducted experimental studies on spray deposition rate and atomization effect, while some foreign scholars have carried out atomization simulation and coating motion characteristics research based on computational fluid dynamics methods. The above studies are mainly qualitative, with relatively few quantitative studies. Related mechanism studies often need to be verified by combining experimental and numerical studies.

[0003] Compared to other painting industries such as automobiles and furniture, the painting process for ship hull plating is more complex, involving a wider variety of paints. Based on the process, it can be divided into several types: shop primer, anti-rust paint, intermediate coat, and overall hull plating paint. Overall plating includes freeboard, waterline, and straight bottom sections. Depending on the purpose and requirements of the hull plating painting, the paint material and film thickness requirements vary. Furthermore, painting operations must be completed in a dry dock, and variations in the hull plating structure, equipment used, and seasonal environmental factors all affect the painting process. Experimental research, especially the measurement of atomized droplet diameter and velocity, requires complex and expensive equipment, involves extensive preparation, and makes accurate monitoring of the intermediate atomization process difficult. Due to limitations in experimental conditions and cost, experiments are typically limited to a few representative painting conditions. Therefore, numerical simulation is increasingly widely used in hull plating painting research. It can meet the simulation needs of diverse paint materials, wide operating environments, and complex painting equipment, and can monitor the intermediate painting process. However, current spraying simulations do not fully connect the movement of paint inside and outside the spray gun cavity. Generally, the simulation of the flow field inside and outside the nozzle is carried out separately. The selection of atomization simulation parameters in the external flow field often depends on experiments or experience. The simulation is used to verify experimental research, but the results obtained from the external flow field are not fed back to the design and structural selection of the nozzle cavity. General-purpose spray guns may have the disadvantages of poor atomization effect and high pressure loss in certain working environments. Summary of the Invention

[0004] The purpose of this invention is to provide a CFD-based ship coating simulation and modeling method that solves the problems of high cost, large number of experiments, poor atomization effect, and high pressure loss in the hull coating experiment of a base ship by establishing a simulation model of two flow fields, inside and outside.

[0005] The present invention proposes a CFD-based simulation and modeling method for ship coating, comprising the following steps: establishing an internal flow field simulation model; establishing an external flow field simulation model; and performing simulation calculations.

[0006] The establishment of the internal flow field simulation model includes: S1: establishing a nozzle inner cavity model for simulating hull plating spraying; S2: using the nozzle inner cavity model to perform internal flow field simulation for hull plating spraying, obtaining the relationship between pressure changes and flow rates for nozzles of different types and structures; the internal flow field spraying simulation is used to simulate the coating being pressurized by a pump station and delivered to the nozzle inner cavity, where pressure energy is converted into kinetic energy and then ejected at high speed from the nozzle tip. The corresponding flow field model is the nozzle inner cavity model. The coating is in a state of high-pressure accelerated motion within the inner cavity, without secondary atomization of the coating, and can be considered as a single-phase motion of the coating liquid.

[0007] The establishment of the external flow field simulation model includes: defining a numerical model for the external flow field simulation based on the results obtained from the internal flow field, including a discrete phase model, a virtual nozzle and its parameters, a turbulence model, and boundary conditions;

[0008] The simulation calculation includes: adjusting the spraying control parameters or improving the nozzle internal cavity structure and nozzle model based on the simulation results of the external flow field of the hull hull spraying; analyzing and judging whether the control parameters of the simulated spraying are acceptable; if acceptable, obtaining acceptable control parameters and nozzle structure and model; if unacceptable, changing the pressure or nozzle structure and model; and simulating the external flow field again based on the relationship results obtained from the internal flow field simulation until acceptable control parameters or nozzle structure and model are obtained.

[0009] In step S1, the nozzle inner cavity model needs to refer to the actual nozzle model and structure, and ensure that the opening area of ​​the front spherical nozzle and the area of ​​the equivalent diameter nozzle are equal according to the physical meaning of the equivalent diameter of the nozzle model.

[0010] Step S2 specifically includes:

[0011] Mesh the nozzle cavity based on the geometric model of the nozzle cavity, obtain the mesh model of the nozzle cavity, and import it into CFD software.

[0012] Based on the flow state of the coating in the internal flow field, a viscous calculation model is set in the CFD software, and the inlet boundary conditions are defined according to the spraying pressure.

[0013] Through CFD numerical simulation, the pressure-flow relationship and other simulation results of the current model and structure of nozzle were obtained.

[0014] The established external flow field simulation model is large enough to encompass the theoretical spraying fan, and the flow field boundary has sufficient distance from the virtual nozzle to reduce the impact of boundary initialization on the spraying simulation, so as to closely approximate the actual spraying working environment.

[0015] The numerical model for simulating external flow field spraying specifically includes:

[0016] A continuous phase numerical model and a discrete phase numerical model are set up. The continuous phase numerical model is used to control the movement of gas in the external flow field. The discrete phase numerical model includes defining the type, position, size, and jet flow information of the virtual nozzle. The selection of the virtual nozzle type needs to be determined by referring to the actual nozzle and simulation software to ensure that the jet distribution and paint atomization of the virtual nozzle match the actual spraying as much as possible.

[0017] The simulation incorporates a coupling of continuous and discrete phases to account for the interaction between the coating and the gas, particularly the gas's influence on coating atomization and motion. The external flow field spraying simulation model depicts the secondary atomization stage where the coating is ejected from the nozzle and interacts with the surrounding air to form numerous discrete droplets. The flow field contains a two-phase fluid of air and coating droplets. Due to the intense coupling between the high-speed moving coating and the surrounding air, the coating atomization can be considered a discontinuous, discrete process. Therefore, the simulation in the external flow field involves a two-way coupling solution of the continuous and discrete phases.

[0018] Based on the atomization properties of the paint in actual spraying, select the atomization model in the CFD software and set the atomization parameters in the model;

[0019] We consider collisions and merging between atomized particles and control the tracking of particle trajectories in order to study the expansion and splashing motion of particles in the watershed.

[0020] The definition of virtual nozzle jet information in the external flow field simulation model uses the results of the internal flow field simulation. Specifically, different flow rates are set for nozzles of different structures and models under different simulation pressures. The internal and external flow field spraying simulations are connected through pressure-flow interaction laws. Since paint atomization in the external flow field is a discontinuous process involving complex atomization theories such as random secondary fragmentation, the internal cavity model from the internal flow field spraying simulation cannot be directly used. Therefore, in the external flow field spraying simulation, depending on the CFD software used, a suitable virtual nozzle type is selected from the discrete phase model, and the pressure and flow interaction laws obtained from the internal flow field simulation are used to define the virtual nozzle jet information.

[0021] The numerical model for the external flow field spraying simulation includes a continuous phase numerical model and a discrete phase numerical model. The flow field model for the external flow field spraying simulation is used to define the boundaries and extent of the flow domains for the continuous phase gas and the discrete phase particles. The boundary conditions of the external flow field simulation model include continuous phase (gas phase) boundary elements and discrete phase (droplet) boundary elements. The continuous phase boundary elements are used to control the motion of the gas phase in the flow field, including velocity inlet, pressure outlet, and other flow field wall boundaries. The discrete phase boundary elements are used to control the trajectory fate of atomized droplets when they reach the flow field boundary, including escape, adhesion, and deposition.

[0022] In the simulation calculation step, the control parameters for simulated spraying include spraying pressure, spraying distance, spraying speed, diffusion angle, and atomization constant.

[0023] The improved nozzle internal cavity structure and nozzle model include: optimization of the length and contraction angle of the internal cavity inlet section, outlet section, and contraction section. If the spraying simulation results still do not meet the expected spraying requirements, the nozzle model can be further changed. The adjustment of spraying control parameters and the improvement of nozzle internal cavity structure and model are based on the idea of ​​cyclic optimization. After multiple cyclic simulations, the spraying control parameters and nozzle internal cavity model and structural design scheme that meet the spraying requirements can be finally obtained.

[0024] The definition of the boundary conditions of the external flow field model can simulate the relative motion between the virtual nozzle and the spraying plate. That is, according to the motion conversion principle, the nozzle drags out a stable liquid film on the spraying plate according to the spraying speed.

[0025] This invention, based on the motion characteristics of paint inside and outside the nozzle during hull plating spraying, divides the hull plating spraying simulation into two parts: internal flow field spraying simulation and external flow field spraying simulation. Each part employs a different flow field model. According to the motion characteristics of paint inside and outside the nozzle cavity, the hull plating spraying simulation is divided into internal and external flow field parts, offering advantages such as short simulation cycle and high efficiency. Through multiple simulation comparisons, suitable spraying control parameters and nozzle internal cavity models and structures can be obtained. In-depth simulation research on problems existing in actual spraying can guide the improvement of spraying processes and the optimization of spray gun structure design, and its application should be broad. Attached Figure Description

[0026] Figure 1 The diagram shows a flowchart of an embodiment of a CFD-based ship painting simulation and modeling method proposed in this invention.

[0027] Figure 2 As shown Figure 1 Three-dimensional models of the inner cavities of four fan-shaped nozzles (a, b, c, and d) used in the internal flow field spraying simulation established in step S1. Detailed implementation method:

[0028] See Figure 1 , Figure 2 These two figures show a flowchart of a CFD-based simulation and modeling method for ship painting proposed in this invention, and three-dimensional model diagrams of the inner cavities of four types of fan-shaped nozzles. The method includes the following steps: establishing an internal flow field simulation model; establishing an external flow field simulation model; and simulation calculation.

[0029] like Figure 1 As shown, the establishment of the internal flow field simulation model includes: Step S1: Establishing a nozzle inner cavity model for hull plating spraying simulation; Step S2: Using the nozzle inner cavity model to perform internal flow field simulation for hull plating spraying, obtaining the relationship between pressure changes and flow rates of nozzles of different types and structures; The internal flow field spraying simulation is used to simulate the coating being pressurized by a pump station and sent to the nozzle inner cavity, where pressure energy is converted into kinetic energy and then sprayed at high speed from the nozzle tip. The corresponding flow field model is the nozzle inner cavity model. The coating is in a state of high-pressure accelerated motion within the inner cavity, without involving secondary atomization of the coating, and can be regarded as a single-phase motion of the coating liquid.

[0030] The establishment of the external flow field simulation model includes: defining a numerical model for the external flow field simulation based on the results obtained from the internal flow field, including a discrete phase model, a virtual nozzle and its parameters, a turbulence model, and boundary conditions;

[0031] The simulation calculation includes: adjusting the spraying control parameters or improving the nozzle internal cavity structure and nozzle model based on the simulation results of the external flow field of the hull hull spraying; analyzing and judging whether the control parameters of the simulated spraying are acceptable; if acceptable, obtaining acceptable control parameters and nozzle structure and model; if unacceptable, changing the pressure or nozzle structure and model; and simulating the external flow field again based on the relationship results obtained from the internal flow field simulation until acceptable control parameters or nozzle structure and model are obtained.

[0032] Step S1 refers to establishing a nozzle internal cavity model for simulating hull plating spraying. This nozzle internal cavity model needs to reference the actual nozzle model and structure, ensuring that the opening area of ​​the front-end spherical nozzle is equal to the area of ​​the equivalent diameter nozzle, based on the physical meaning of the nozzle model's equivalent diameter. In high-pressure airless spraying, fan-shaped nozzles can be classified into four types according to their internal cavity inlet structure: flat-top, parallel, conical, and Vidosinski cavity. Figure 2This refers to the three-dimensional models of the internal cavities of four types of fan-shaped nozzles. The nozzle model is mainly composed of two parameters: orifice diameter and spray width. Under a certain spraying distance and pressure, the nozzle orifice diameter determines the outgoing flow rate. Therefore, modeling the flow field within the nozzle cavity requires reference to the cavity structure and the nozzle model. In high-pressure airless spraying, the actual structure of the nozzle's front section is typically an ellipsoidal structure with a V-groove. The orifice diameter in the actual spray gun model indicates that the flow rate of the nozzle at a given inlet pressure is the same as that of a circular nozzle with an equivalent orifice diameter. Assuming the nozzle outgoing velocity is the same, it is only necessary to ensure that the outlet area of ​​the actual nozzle is the same as the area of ​​a circular nozzle with an equivalent orifice diameter. In practice, for nozzles of the same model, i.e., with the equivalent orifice diameter unchanged, nozzles with the same orifice diameter but different internal cavity structures can be obtained by changing the nozzle's contraction section length, contraction angle, outlet diameter, and opening angle.

[0033] Step S2 represents setting the atomization pressure for nozzles of different models and structures. The atomization pressure of the internal flow field is the initial control parameter that directly affects the external flow field control parameter—the injection volume. Specifically, it includes the following steps: Meshing the internal flow field model according to the nozzle's internal cavity geometric model, as shown in step S3 of the flowchart. Meshing is performed based on the flow field's requirements for mesh accuracy. To ensure simulation accuracy, mesh refinement is performed at the nozzle location, and mesh independence is checked to ensure the calculated results are not affected by mesh accuracy. This yields the mesh model of the nozzle's internal cavity, which is then imported into the CFD software. Based on the flow state of the coating in the internal flow field, a viscosity calculation model is set in the CFD software, and the inlet boundary conditions are defined according to the spraying pressure. Through CFD numerical simulation, the pressure-flow relationship and other simulation results for the current model and structure of the nozzle are obtained. Step S4 in the diagram represents simulating the internal flow field model established for each model and structure of nozzle. Based on the Reynolds number of the coating motion within the nozzle cavity, the motion state of the coating is determined. A suitable viscosity model and the atomization parameters determined in step S2 are then selected to perform CFD simulation of the internal flow field during hull plating spraying. Step S5 in the figure shows the flow rate results obtained from simulations of nozzle models with different structures under different pressures. The relationship between pressure and flow rate is output to facilitate external flow field spraying simulation.

[0034] Step S6 in the figure represents creating an external flow field model for hull plating spraying simulation. In order to simulate hull plating spraying under natural conditions, the size of the external flow field simulation model should be large enough to not only cover the spraying fan of the virtual nozzle, but also include the virtual nozzle. The flow field boundary and the virtual nozzle should have sufficient distance to reduce the impact of boundary initialization on the spraying simulation and reduce its impact on the numerical simulation within the external flow field, so as to approximate the actual spraying working environment as closely as possible.

[0035] The numerical model for simulating the external flow field spraying is defined as follows: Step S7 in the figure, based on the relationship results obtained in step S5 and the simulation object, defines the solution model for the external flow field simulation. The solution model to be defined includes a discrete phase model, a virtual nozzle and its parameters, a turbulence model, boundary conditions, etc. Among them, the continuous phase is used to control the movement of gas in the external flow field. Because high-pressure airless spraying is used, the air flow field in the external flow field is relatively turbulent, with phenomena such as airflow turbulence. Therefore, a turbulence model is selected. The discrete phase model is applicable because the spraying simulation in the external flow field involves a gas-liquid two-phase flow problem, requiring separate setting of the control equations for the two phases and bidirectional coupling. The virtual nozzle and its parameters mainly include the following: the definition of information such as the type, position, size, and jet flow rate of the virtual nozzle; wherein, the jet flow rate of the nozzle is obtained according to step S5 based on different pressures under different types and structures of nozzles, and the nozzle opening area is equal to the flow area of ​​a circular nozzle with an equivalent diameter; the coupling setting of the continuous phase and the discrete phase is to consider the mutual influence between the coating and the gas, especially the influence of the gas on the atomization and motion of the coating; according to the actual atomization characteristics of the coating, a suitable atomization model is selected in the CFD software, and the atomization parameters in the model are set; the collision and merging between atomized particles are considered, and the tracking of particle trajectories is set to study the atomization and splashing of the coating in the external flow field. The boundary conditions of the external flow field model can be divided into continuous phase boundary elements and discrete phase boundary elements. The continuous phase boundary elements are used to control the motion of the gas in the external flow field, including the inlet boundary, the outlet boundary, and the remaining flow field wall boundaries. To simulate different spray gun velocities, the sprayed outer plate and virtual nozzle in the external flow field model need to maintain relative motion. In the simulation, the continuous phase boundary type of the sprayed outer plate is set as a moving wall, its motion is translation, and its velocity is set as the spraying velocity value. The direction vector of the motion is defined according to the motion conversion principle. Discrete phase boundary elements are used to control the trajectory fate of atomized droplets when they reach the flow field boundary, including escape, adhesion, and deposition types. The paint mist deposition discrete phase boundary type is used to determine the trajectory on the sprayed outer plate in the external flow field model, indicating that when particles reach the hull hull, they undergo partial deposition through breaking, splashing, and spreading. The splashed paint mist will move within the recovery hood.

[0036] Trajectory tracking of particles at this boundary continues.

[0037]

[0038] In the formula, m p The mass of the particles; The velocity of the continuous phase; ρ is the particle velocity; ρ is the density of the continuous phase; ρp is the particle density. For additional force; τr is the drag force of the particle; τr is the relaxation time of the particle.

[0039] Step S8 indicates that the external flow field model is meshed; the mesh is meshed according to the flow field's requirements for mesh accuracy; in order to facilitate the tracking of particles in the area of ​​intense atomization near the virtual nozzle, the mesh of the external flow field model needs to be refined near the spray fan; mesh independence is checked to ensure that the calculated results are not affected by the mesh accuracy.

[0040] Step S9 indicates that the content defined in the above steps is calculated using Fluent software.

[0041] In the simulation calculation step, the control parameters for simulated spraying include spraying pressure, spraying distance, spraying speed, diffusion angle, and atomization constant. Step S10 represents post-processing based on the simulation results to obtain the liquid film thickness, paint utilization rate, and film thickness uniformity under different control parameters and nozzle models and structures. These three results are important indicators for evaluating the spraying effect. Based on the feasibility of these judgment parameters and nozzle structures and models, if feasible, proceed to step S11; otherwise, return to step S7 for iterative optimization until a satisfactory result is obtained.

[0042] The improvement of the nozzle inner cavity structure and nozzle model includes: optimization of the length and contraction angle of the inner cavity inlet section, outlet section, and contraction section. If the spraying simulation results still do not meet the expected spraying requirements, the nozzle model can be further changed. The adjustment of spraying control parameters and the improvement of nozzle inner cavity structure and model are based on the idea of ​​cyclic optimization. After multiple cyclic simulations, step S11 indicates that after multiple cycles, when the simulation results are acceptable, reasonable control parameters for spraying the hull hull and nozzle inner cavity structure and model are output, which can ultimately obtain spraying control parameters and nozzle inner cavity model and structural design scheme that meet the spraying requirements.

[0043] The definition of the boundary conditions of the external flow field model can simulate the relative motion between the virtual nozzle and the spraying plate. That is, according to the motion conversion principle, the nozzle drags out a stable liquid film on the spraying plate according to the spraying speed.

[0044] This invention proposes a CFD-based simulation and modeling method for ship coating. Based on CFD technology and the concept of iterative optimization, it allows for multiple simulation optimizations with lower time and computational costs. The simulation results of the flow field inside the nozzle are used for the external flow field simulation of the hull plating, ensuring data consistency. Conversely, the results of the external flow field simulation are fed back to the selection of coating control parameters, internal cavity design, and nozzle selection, providing guidance for actual coating control and nozzle design and selection, thus possessing significant practical value.

[0045] The above embodiments are only used to illustrate the present invention. The specific implementation algorithms, models, etc. used therein can be varied. Any equivalent transformations and improvements made on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.

Claims

1. A CFD-based method for ship painting simulation and modeling, characterized in that: The process includes the following steps: establishing an internal flow field simulation model; establishing an external flow field simulation model; and performing simulation calculations. The establishment of the internal flow field simulation model includes: S1: Establish nozzle internal cavity models of different types or structures for simulating the spraying of ship hull plates; S2: Set the atomization pressure of the nozzle, use the nozzle inner cavity model to simulate the internal flow field of the ship's outer plate spraying, and obtain the relationship between pressure change and flow rate of nozzles of different types and structures. The establishment of the external flow field simulation model includes: defining a numerical model for the external flow field simulation based on the results obtained from the internal flow field, including a discrete phase model, a virtual nozzle and its parameters, a turbulence model, and boundary conditions; The simulation calculation includes: adjusting the spraying control parameters or improving the nozzle internal cavity structure and nozzle model based on the simulation results of the external flow field of the hull hull spraying; analyzing and judging whether the spraying control parameters are acceptable; if acceptable, obtaining acceptable control parameters and nozzle structure and model; if unacceptable, changing the spraying control parameters or nozzle structure and model; and simulating the external flow field again based on the relationship results obtained from the internal flow field simulation until acceptable control parameters or nozzle structure and model are obtained.

2. The CFD-based ship painting simulation and modeling method according to claim 1, characterized in that: In step S1, the nozzle inner cavity model needs to refer to the actual nozzle model and structure, and ensure that the opening area of ​​the front spherical nozzle and the area of ​​the equivalent diameter nozzle are equal according to the physical meaning of the equivalent diameter of the nozzle model.

3. The CFD-based ship painting simulation and modeling method according to claim 1, characterized in that: Step S2 specifically includes: Mesh the nozzle cavity based on the geometric model of the nozzle cavity, obtain the mesh model of the nozzle cavity, and import it into CFD software. Based on the flow state of the coating in the internal flow field, a viscous calculation model is set in the CFD software, and the inlet boundary conditions are defined according to the spraying pressure. Through CFD numerical simulation, the pressure-flow relationship and other simulation results of the current model and structure of nozzle were obtained.

4. The CFD-based ship painting simulation and modeling method according to claim 1, characterized in that: The established external flow field simulation model is large enough to encompass the theoretical spraying fan, and the flow field boundary has sufficient distance from the virtual nozzle to reduce the impact of boundary initialization on the spraying simulation, so as to closely approximate the actual spraying working environment.

5. The CFD-based simulation and modeling method for ship painting according to claim 1, characterized in that: The numerical model for simulating external flow field spraying specifically includes the following steps: A continuous phase numerical model and a discrete phase numerical model are set up. The continuous phase numerical model is used to control the movement of gas in the external flow field. The discrete phase numerical model includes: defining the type, position, size, and jet flow information of the virtual nozzle. The selection of the virtual nozzle type needs to be determined by referring to the actual nozzle and simulation software to ensure that the jet distribution and paint atomization of the virtual nozzle match the actual spraying as much as possible. The coupling of continuous and discrete phases is set up to account for the interaction between coating and gas, especially the effect of gas on coating atomization and motion; Based on the atomization properties of the paint in actual spraying, select the atomization model in the CFD software and set the atomization parameters in the model; We consider collisions and merging between atomized particles and control the tracking of particle trajectories in order to study the expansion and splashing motion of particles in the watershed.

6. The CFD-based simulation and modeling method for ship painting according to claim 1, characterized in that: The definition of the virtual nozzle jet information in the external flow field simulation model uses the results of the internal flow field simulation, that is, different flow rates are set for nozzles of different structures and models under different simulation pressures.

7. The CFD-based ship painting simulation and modeling method according to claim 1, characterized in that: The boundary conditions of the external flow field simulation model include boundary elements of the continuous phase (gas phase) and boundary elements of the discrete phase (droplets). The continuous phase boundary elements are used to control the movement of the gas phase in the flow field, including velocity inlet, pressure outlet and other flow field wall boundaries. The discrete phase boundary elements are used to control the trajectory fate of atomized droplets when they reach the flow field boundary, including escape, attachment and deposition.

8. The CFD-based simulation and modeling method for ship painting according to claim 1, characterized in that: In the simulation calculation step, the control parameters for simulated spraying include spraying pressure, spraying distance, spraying speed, diffusion angle, and atomization constant.

9. The CFD-based simulation and modeling method for ship painting according to claim 1, characterized in that: The improved nozzle internal cavity structure and nozzle model include: optimization of the length and contraction angle of the internal cavity inlet section, outlet section, and contraction section. If the spraying simulation results still do not meet the expected spraying requirements, the nozzle model will be further changed.

10. The CFD-based simulation and modeling method for ship painting according to claim 7, characterized in that: The boundary conditions of the external flow field simulation model are defined to simulate the relative motion between the virtual nozzle and the spraying plate. That is, according to the motion conversion principle, the nozzle drags out a stable liquid film on the spraying plate according to the spraying speed.

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